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-rw-r--r--sys/contrib/openzfs/module/zfs/Makefile.in153
-rw-r--r--sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash19
-rw-r--r--sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash.descrip1
-rw-r--r--sys/contrib/openzfs/module/zfs/abd.c1213
-rw-r--r--sys/contrib/openzfs/module/zfs/aggsum.c237
-rw-r--r--sys/contrib/openzfs/module/zfs/arc.c10582
-rw-r--r--sys/contrib/openzfs/module/zfs/blkptr.c153
-rw-r--r--sys/contrib/openzfs/module/zfs/bplist.c91
-rw-r--r--sys/contrib/openzfs/module/zfs/bpobj.c943
-rw-r--r--sys/contrib/openzfs/module/zfs/bptree.c303
-rw-r--r--sys/contrib/openzfs/module/zfs/bqueue.c155
-rw-r--r--sys/contrib/openzfs/module/zfs/btree.c2124
-rw-r--r--sys/contrib/openzfs/module/zfs/dataset_kstats.c215
-rw-r--r--sys/contrib/openzfs/module/zfs/dbuf.c4741
-rw-r--r--sys/contrib/openzfs/module/zfs/dbuf_stats.c231
-rw-r--r--sys/contrib/openzfs/module/zfs/ddt.c1187
-rw-r--r--sys/contrib/openzfs/module/zfs/ddt_zap.c168
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu.c2483
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_diff.c240
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_object.c525
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_objset.c2992
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_recv.c3386
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_redact.c1186
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_send.c3091
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_traverse.c786
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_tx.c1404
-rw-r--r--sys/contrib/openzfs/module/zfs/dmu_zfetch.c384
-rw-r--r--sys/contrib/openzfs/module/zfs/dnode.c2575
-rw-r--r--sys/contrib/openzfs/module/zfs/dnode_sync.c856
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_bookmark.c1742
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_crypt.c2872
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_dataset.c5027
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_deadlist.c1012
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_deleg.c774
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_destroy.c1286
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_dir.c2403
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_pool.c1384
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_prop.c1287
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_scan.c4426
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_synctask.c261
-rw-r--r--sys/contrib/openzfs/module/zfs/dsl_userhold.c691
-rw-r--r--sys/contrib/openzfs/module/zfs/edonr_zfs.c115
-rw-r--r--sys/contrib/openzfs/module/zfs/fm.c1674
-rw-r--r--sys/contrib/openzfs/module/zfs/gzip.c106
-rw-r--r--sys/contrib/openzfs/module/zfs/hkdf.c171
-rw-r--r--sys/contrib/openzfs/module/zfs/lz4.c1031
-rw-r--r--sys/contrib/openzfs/module/zfs/lzjb.c132
-rw-r--r--sys/contrib/openzfs/module/zfs/metaslab.c6236
-rw-r--r--sys/contrib/openzfs/module/zfs/mmp.c728
-rw-r--r--sys/contrib/openzfs/module/zfs/multilist.c431
-rw-r--r--sys/contrib/openzfs/module/zfs/objlist.c84
-rw-r--r--sys/contrib/openzfs/module/zfs/pathname.c96
-rw-r--r--sys/contrib/openzfs/module/zfs/range_tree.c921
-rw-r--r--sys/contrib/openzfs/module/zfs/refcount.c327
-rw-r--r--sys/contrib/openzfs/module/zfs/rrwlock.c396
-rw-r--r--sys/contrib/openzfs/module/zfs/sa.c2257
-rw-r--r--sys/contrib/openzfs/module/zfs/sha256.c105
-rw-r--r--sys/contrib/openzfs/module/zfs/skein_zfs.c102
-rw-r--r--sys/contrib/openzfs/module/zfs/spa.c9755
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_boot.c50
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_checkpoint.c636
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_config.c620
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_errlog.c416
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_history.c629
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_log_spacemap.c1322
-rw-r--r--sys/contrib/openzfs/module/zfs/spa_misc.c2921
-rw-r--r--sys/contrib/openzfs/module/zfs/space_map.c1105
-rw-r--r--sys/contrib/openzfs/module/zfs/space_reftree.c152
-rw-r--r--sys/contrib/openzfs/module/zfs/txg.c1059
-rw-r--r--sys/contrib/openzfs/module/zfs/uberblock.c74
-rw-r--r--sys/contrib/openzfs/module/zfs/unique.c112
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev.c5090
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_cache.c437
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_indirect.c1890
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_indirect_births.c226
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_indirect_mapping.c616
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_initialize.c750
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_label.c1901
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_mirror.c863
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_missing.c113
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_queue.c1070
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz.c2421
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math.c666
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_aarch64_neon.c2279
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_aarch64_neon_common.h684
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_aarch64_neonx2.c232
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_avx2.c413
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_avx512bw.c413
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_avx512f.c494
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_impl.h1477
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_powerpc_altivec.c4337
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_powerpc_altivec_common.h690
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_scalar.c337
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_sse2.c631
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_raidz_math_ssse3.c2477
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_rebuild.c1108
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_removal.c2340
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_root.c158
-rw-r--r--sys/contrib/openzfs/module/zfs/vdev_trim.c1701
-rw-r--r--sys/contrib/openzfs/module/zfs/zap.c1384
-rw-r--r--sys/contrib/openzfs/module/zfs/zap_leaf.c849
-rw-r--r--sys/contrib/openzfs/module/zfs/zap_micro.c1697
-rw-r--r--sys/contrib/openzfs/module/zfs/zcp.c1456
-rw-r--r--sys/contrib/openzfs/module/zfs/zcp_get.c813
-rw-r--r--sys/contrib/openzfs/module/zfs/zcp_global.c89
-rw-r--r--sys/contrib/openzfs/module/zfs/zcp_iter.c751
-rw-r--r--sys/contrib/openzfs/module/zfs/zcp_set.c100
-rw-r--r--sys/contrib/openzfs/module/zfs/zcp_synctask.c544
-rw-r--r--sys/contrib/openzfs/module/zfs/zfeature.c526
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_byteswap.c211
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_fm.c1083
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_fuid.c815
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_ioctl.c7629
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_log.c774
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_onexit.c173
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_quota.c476
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_ratelimit.c99
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_replay.c992
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_rlock.c691
-rw-r--r--sys/contrib/openzfs/module/zfs/zfs_sa.c445
-rw-r--r--sys/contrib/openzfs/module/zfs/zil.c3688
-rw-r--r--sys/contrib/openzfs/module/zfs/zio.c4969
-rw-r--r--sys/contrib/openzfs/module/zfs/zio_checksum.c570
-rw-r--r--sys/contrib/openzfs/module/zfs/zio_compress.c220
-rw-r--r--sys/contrib/openzfs/module/zfs/zio_inject.c966
-rw-r--r--sys/contrib/openzfs/module/zfs/zle.c91
-rw-r--r--sys/contrib/openzfs/module/zfs/zrlock.c188
-rw-r--r--sys/contrib/openzfs/module/zfs/zthr.c536
-rw-r--r--sys/contrib/openzfs/module/zfs/zvol.c1729
129 files changed, 169720 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/module/zfs/Makefile.in b/sys/contrib/openzfs/module/zfs/Makefile.in
new file mode 100644
index 000000000000..9ddcd6c339d4
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/Makefile.in
@@ -0,0 +1,153 @@
+ifneq ($(KBUILD_EXTMOD),)
+src = @abs_srcdir@
+obj = @abs_builddir@
+mfdir = $(obj)
+else
+mfdir = $(srctree)/$(src)
+endif
+
+MODULE := zfs
+
+obj-$(CONFIG_ZFS) := $(MODULE).o
+
+# Suppress unused-value warnings in sparc64 architecture headers
+ccflags-$(CONFIG_SPARC64) += -Wno-unused-value
+
+$(MODULE)-objs += abd.o
+$(MODULE)-objs += aggsum.o
+$(MODULE)-objs += arc.o
+$(MODULE)-objs += blkptr.o
+$(MODULE)-objs += bplist.o
+$(MODULE)-objs += bpobj.o
+$(MODULE)-objs += bptree.o
+$(MODULE)-objs += btree.o
+$(MODULE)-objs += bqueue.o
+$(MODULE)-objs += dataset_kstats.o
+$(MODULE)-objs += dbuf.o
+$(MODULE)-objs += dbuf_stats.o
+$(MODULE)-objs += ddt.o
+$(MODULE)-objs += ddt_zap.o
+$(MODULE)-objs += dmu.o
+$(MODULE)-objs += dmu_diff.o
+$(MODULE)-objs += dmu_object.o
+$(MODULE)-objs += dmu_objset.o
+$(MODULE)-objs += dmu_recv.o
+$(MODULE)-objs += dmu_redact.o
+$(MODULE)-objs += dmu_send.o
+$(MODULE)-objs += dmu_traverse.o
+$(MODULE)-objs += dmu_tx.o
+$(MODULE)-objs += dmu_zfetch.o
+$(MODULE)-objs += dnode.o
+$(MODULE)-objs += dnode_sync.o
+$(MODULE)-objs += dsl_bookmark.o
+$(MODULE)-objs += dsl_crypt.o
+$(MODULE)-objs += dsl_dataset.o
+$(MODULE)-objs += dsl_deadlist.o
+$(MODULE)-objs += dsl_deleg.o
+$(MODULE)-objs += dsl_destroy.o
+$(MODULE)-objs += dsl_dir.o
+$(MODULE)-objs += dsl_pool.o
+$(MODULE)-objs += dsl_prop.o
+$(MODULE)-objs += dsl_scan.o
+$(MODULE)-objs += dsl_synctask.o
+$(MODULE)-objs += dsl_userhold.o
+$(MODULE)-objs += edonr_zfs.o
+$(MODULE)-objs += fm.o
+$(MODULE)-objs += gzip.o
+$(MODULE)-objs += hkdf.o
+$(MODULE)-objs += lz4.o
+$(MODULE)-objs += lzjb.o
+$(MODULE)-objs += metaslab.o
+$(MODULE)-objs += mmp.o
+$(MODULE)-objs += multilist.o
+$(MODULE)-objs += objlist.o
+$(MODULE)-objs += pathname.o
+$(MODULE)-objs += range_tree.o
+$(MODULE)-objs += refcount.o
+$(MODULE)-objs += rrwlock.o
+$(MODULE)-objs += sa.o
+$(MODULE)-objs += sha256.o
+$(MODULE)-objs += skein_zfs.o
+$(MODULE)-objs += spa.o
+$(MODULE)-objs += spa_boot.o
+$(MODULE)-objs += spa_checkpoint.o
+$(MODULE)-objs += spa_config.o
+$(MODULE)-objs += spa_errlog.o
+$(MODULE)-objs += spa_history.o
+$(MODULE)-objs += spa_log_spacemap.o
+$(MODULE)-objs += spa_misc.o
+$(MODULE)-objs += space_map.o
+$(MODULE)-objs += space_reftree.o
+$(MODULE)-objs += txg.o
+$(MODULE)-objs += uberblock.o
+$(MODULE)-objs += unique.o
+$(MODULE)-objs += vdev.o
+$(MODULE)-objs += vdev_cache.o
+$(MODULE)-objs += vdev_indirect.o
+$(MODULE)-objs += vdev_indirect_births.o
+$(MODULE)-objs += vdev_indirect_mapping.o
+$(MODULE)-objs += vdev_initialize.o
+$(MODULE)-objs += vdev_label.o
+$(MODULE)-objs += vdev_mirror.o
+$(MODULE)-objs += vdev_missing.o
+$(MODULE)-objs += vdev_queue.o
+$(MODULE)-objs += vdev_raidz.o
+$(MODULE)-objs += vdev_raidz_math.o
+$(MODULE)-objs += vdev_raidz_math_scalar.o
+$(MODULE)-objs += vdev_rebuild.o
+$(MODULE)-objs += vdev_removal.o
+$(MODULE)-objs += vdev_root.o
+$(MODULE)-objs += vdev_trim.o
+$(MODULE)-objs += zap.o
+$(MODULE)-objs += zap_leaf.o
+$(MODULE)-objs += zap_micro.o
+$(MODULE)-objs += zcp.o
+$(MODULE)-objs += zcp_get.o
+$(MODULE)-objs += zcp_global.o
+$(MODULE)-objs += zcp_iter.o
+$(MODULE)-objs += zcp_set.o
+$(MODULE)-objs += zcp_synctask.o
+$(MODULE)-objs += zfeature.o
+$(MODULE)-objs += zfs_byteswap.o
+$(MODULE)-objs += zfs_fm.o
+$(MODULE)-objs += zfs_fuid.o
+$(MODULE)-objs += zfs_ioctl.o
+$(MODULE)-objs += zfs_log.o
+$(MODULE)-objs += zfs_onexit.o
+$(MODULE)-objs += zfs_quota.o
+$(MODULE)-objs += zfs_ratelimit.o
+$(MODULE)-objs += zfs_replay.o
+$(MODULE)-objs += zfs_rlock.o
+$(MODULE)-objs += zfs_sa.o
+$(MODULE)-objs += zil.o
+$(MODULE)-objs += zio.o
+$(MODULE)-objs += zio_checksum.o
+$(MODULE)-objs += zio_compress.o
+$(MODULE)-objs += zio_inject.o
+$(MODULE)-objs += zle.o
+$(MODULE)-objs += zrlock.o
+$(MODULE)-objs += zthr.o
+$(MODULE)-objs += zvol.o
+
+# Suppress incorrect warnings from versions of objtool which are not
+# aware of x86 EVEX prefix instructions used for AVX512.
+OBJECT_FILES_NON_STANDARD_vdev_raidz_math_avx512bw.o := y
+OBJECT_FILES_NON_STANDARD_vdev_raidz_math_avx512f.o := y
+
+$(MODULE)-$(CONFIG_X86) += vdev_raidz_math_sse2.o
+$(MODULE)-$(CONFIG_X86) += vdev_raidz_math_ssse3.o
+$(MODULE)-$(CONFIG_X86) += vdev_raidz_math_avx2.o
+$(MODULE)-$(CONFIG_X86) += vdev_raidz_math_avx512f.o
+$(MODULE)-$(CONFIG_X86) += vdev_raidz_math_avx512bw.o
+
+$(MODULE)-$(CONFIG_ARM64) += vdev_raidz_math_aarch64_neon.o
+$(MODULE)-$(CONFIG_ARM64) += vdev_raidz_math_aarch64_neonx2.o
+
+$(MODULE)-$(CONFIG_PPC) += vdev_raidz_math_powerpc_altivec.o
+$(MODULE)-$(CONFIG_PPC64) += vdev_raidz_math_powerpc_altivec.o
+
+ifeq ($(CONFIG_ALTIVEC),y)
+$(obj)/vdev_raidz_math_powerpc_altivec.o: c_flags += -maltivec
+endif
+
+include $(mfdir)/../os/linux/zfs/Makefile
diff --git a/sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash b/sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash
new file mode 100644
index 000000000000..e558b2a50358
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash
@@ -0,0 +1,19 @@
+Copyright (c) 2011 Google, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash.descrip b/sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash.descrip
new file mode 100644
index 000000000000..f98cb76dfc91
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/THIRDPARTYLICENSE.cityhash.descrip
@@ -0,0 +1 @@
+CITYHASH CHECKSUM FUNCTIONALITY IN ZFS
diff --git a/sys/contrib/openzfs/module/zfs/abd.c b/sys/contrib/openzfs/module/zfs/abd.c
new file mode 100644
index 000000000000..6018a42ca0d8
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/abd.c
@@ -0,0 +1,1213 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2014 by Chunwei Chen. All rights reserved.
+ * Copyright (c) 2019 by Delphix. All rights reserved.
+ */
+
+/*
+ * ARC buffer data (ABD).
+ *
+ * ABDs are an abstract data structure for the ARC which can use two
+ * different ways of storing the underlying data:
+ *
+ * (a) Linear buffer. In this case, all the data in the ABD is stored in one
+ * contiguous buffer in memory (from a zio_[data_]buf_* kmem cache).
+ *
+ * +-------------------+
+ * | ABD (linear) |
+ * | abd_flags = ... |
+ * | abd_size = ... | +--------------------------------+
+ * | abd_buf ------------->| raw buffer of size abd_size |
+ * +-------------------+ +--------------------------------+
+ * no abd_chunks
+ *
+ * (b) Scattered buffer. In this case, the data in the ABD is split into
+ * equal-sized chunks (from the abd_chunk_cache kmem_cache), with pointers
+ * to the chunks recorded in an array at the end of the ABD structure.
+ *
+ * +-------------------+
+ * | ABD (scattered) |
+ * | abd_flags = ... |
+ * | abd_size = ... |
+ * | abd_offset = 0 | +-----------+
+ * | abd_chunks[0] ----------------------------->| chunk 0 |
+ * | abd_chunks[1] ---------------------+ +-----------+
+ * | ... | | +-----------+
+ * | abd_chunks[N-1] ---------+ +------->| chunk 1 |
+ * +-------------------+ | +-----------+
+ * | ...
+ * | +-----------+
+ * +----------------->| chunk N-1 |
+ * +-----------+
+ *
+ * In addition to directly allocating a linear or scattered ABD, it is also
+ * possible to create an ABD by requesting the "sub-ABD" starting at an offset
+ * within an existing ABD. In linear buffers this is simple (set abd_buf of
+ * the new ABD to the starting point within the original raw buffer), but
+ * scattered ABDs are a little more complex. The new ABD makes a copy of the
+ * relevant abd_chunks pointers (but not the underlying data). However, to
+ * provide arbitrary rather than only chunk-aligned starting offsets, it also
+ * tracks an abd_offset field which represents the starting point of the data
+ * within the first chunk in abd_chunks. For both linear and scattered ABDs,
+ * creating an offset ABD marks the original ABD as the offset's parent, and the
+ * original ABD's abd_children refcount is incremented. This data allows us to
+ * ensure the root ABD isn't deleted before its children.
+ *
+ * Most consumers should never need to know what type of ABD they're using --
+ * the ABD public API ensures that it's possible to transparently switch from
+ * using a linear ABD to a scattered one when doing so would be beneficial.
+ *
+ * If you need to use the data within an ABD directly, if you know it's linear
+ * (because you allocated it) you can use abd_to_buf() to access the underlying
+ * raw buffer. Otherwise, you should use one of the abd_borrow_buf* functions
+ * which will allocate a raw buffer if necessary. Use the abd_return_buf*
+ * functions to return any raw buffers that are no longer necessary when you're
+ * done using them.
+ *
+ * There are a variety of ABD APIs that implement basic buffer operations:
+ * compare, copy, read, write, and fill with zeroes. If you need a custom
+ * function which progressively accesses the whole ABD, use the abd_iterate_*
+ * functions.
+ *
+ * As an additional feature, linear and scatter ABD's can be stitched together
+ * by using the gang ABD type (abd_alloc_gang_abd()). This allows for
+ * multiple ABDs to be viewed as a singular ABD.
+ *
+ * It is possible to make all ABDs linear by setting zfs_abd_scatter_enabled to
+ * B_FALSE.
+ */
+
+#include <sys/abd_impl.h>
+#include <sys/param.h>
+#include <sys/zio.h>
+#include <sys/zfs_context.h>
+#include <sys/zfs_znode.h>
+
+/* see block comment above for description */
+int zfs_abd_scatter_enabled = B_TRUE;
+
+boolean_t
+abd_is_linear(abd_t *abd)
+{
+ return ((abd->abd_flags & ABD_FLAG_LINEAR) != 0 ? B_TRUE : B_FALSE);
+}
+
+boolean_t
+abd_is_linear_page(abd_t *abd)
+{
+ return ((abd->abd_flags & ABD_FLAG_LINEAR_PAGE) != 0 ?
+ B_TRUE : B_FALSE);
+}
+
+boolean_t
+abd_is_gang(abd_t *abd)
+{
+ return ((abd->abd_flags & ABD_FLAG_GANG) != 0 ? B_TRUE :
+ B_FALSE);
+}
+
+void
+abd_verify(abd_t *abd)
+{
+ ASSERT3U(abd->abd_size, >, 0);
+ ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE);
+ ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR |
+ ABD_FLAG_OWNER | ABD_FLAG_META | ABD_FLAG_MULTI_ZONE |
+ ABD_FLAG_MULTI_CHUNK | ABD_FLAG_LINEAR_PAGE | ABD_FLAG_GANG |
+ ABD_FLAG_GANG_FREE | ABD_FLAG_ZEROS));
+ IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER));
+ IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER);
+ if (abd_is_linear(abd)) {
+ ASSERT3P(ABD_LINEAR_BUF(abd), !=, NULL);
+ } else if (abd_is_gang(abd)) {
+ uint_t child_sizes = 0;
+ for (abd_t *cabd = list_head(&ABD_GANG(abd).abd_gang_chain);
+ cabd != NULL;
+ cabd = list_next(&ABD_GANG(abd).abd_gang_chain, cabd)) {
+ ASSERT(list_link_active(&cabd->abd_gang_link));
+ child_sizes += cabd->abd_size;
+ abd_verify(cabd);
+ }
+ ASSERT3U(abd->abd_size, ==, child_sizes);
+ } else {
+ abd_verify_scatter(abd);
+ }
+}
+
+uint_t
+abd_get_size(abd_t *abd)
+{
+ abd_verify(abd);
+ return (abd->abd_size);
+}
+
+/*
+ * Allocate an ABD, along with its own underlying data buffers. Use this if you
+ * don't care whether the ABD is linear or not.
+ */
+abd_t *
+abd_alloc(size_t size, boolean_t is_metadata)
+{
+ if (!zfs_abd_scatter_enabled || abd_size_alloc_linear(size))
+ return (abd_alloc_linear(size, is_metadata));
+
+ VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+ abd_t *abd = abd_alloc_struct(size);
+ abd->abd_flags = ABD_FLAG_OWNER;
+ abd->abd_u.abd_scatter.abd_offset = 0;
+ abd_alloc_chunks(abd, size);
+
+ if (is_metadata) {
+ abd->abd_flags |= ABD_FLAG_META;
+ }
+ abd->abd_size = size;
+ abd->abd_parent = NULL;
+ zfs_refcount_create(&abd->abd_children);
+
+ abd_update_scatter_stats(abd, ABDSTAT_INCR);
+
+ return (abd);
+}
+
+static void
+abd_free_scatter(abd_t *abd)
+{
+ abd_free_chunks(abd);
+
+ zfs_refcount_destroy(&abd->abd_children);
+ abd_update_scatter_stats(abd, ABDSTAT_DECR);
+ abd_free_struct(abd);
+}
+
+static void
+abd_put_gang_abd(abd_t *abd)
+{
+ ASSERT(abd_is_gang(abd));
+ abd_t *cabd;
+
+ while ((cabd = list_remove_head(&ABD_GANG(abd).abd_gang_chain))
+ != NULL) {
+ ASSERT0(cabd->abd_flags & ABD_FLAG_GANG_FREE);
+ abd->abd_size -= cabd->abd_size;
+ abd_put(cabd);
+ }
+ ASSERT0(abd->abd_size);
+ list_destroy(&ABD_GANG(abd).abd_gang_chain);
+}
+
+/*
+ * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not
+ * free the underlying scatterlist or buffer.
+ */
+void
+abd_put(abd_t *abd)
+{
+ if (abd == NULL)
+ return;
+
+ abd_verify(abd);
+ ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
+
+ if (abd->abd_parent != NULL) {
+ (void) zfs_refcount_remove_many(&abd->abd_parent->abd_children,
+ abd->abd_size, abd);
+ }
+
+ if (abd_is_gang(abd))
+ abd_put_gang_abd(abd);
+
+ zfs_refcount_destroy(&abd->abd_children);
+ abd_free_struct(abd);
+}
+
+/*
+ * Allocate an ABD that must be linear, along with its own underlying data
+ * buffer. Only use this when it would be very annoying to write your ABD
+ * consumer with a scattered ABD.
+ */
+abd_t *
+abd_alloc_linear(size_t size, boolean_t is_metadata)
+{
+ abd_t *abd = abd_alloc_struct(0);
+
+ VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+ abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER;
+ if (is_metadata) {
+ abd->abd_flags |= ABD_FLAG_META;
+ }
+ abd->abd_size = size;
+ abd->abd_parent = NULL;
+ zfs_refcount_create(&abd->abd_children);
+
+ if (is_metadata) {
+ ABD_LINEAR_BUF(abd) = zio_buf_alloc(size);
+ } else {
+ ABD_LINEAR_BUF(abd) = zio_data_buf_alloc(size);
+ }
+
+ abd_update_linear_stats(abd, ABDSTAT_INCR);
+
+ return (abd);
+}
+
+static void
+abd_free_linear(abd_t *abd)
+{
+ if (abd_is_linear_page(abd)) {
+ abd_free_linear_page(abd);
+ return;
+ }
+ if (abd->abd_flags & ABD_FLAG_META) {
+ zio_buf_free(ABD_LINEAR_BUF(abd), abd->abd_size);
+ } else {
+ zio_data_buf_free(ABD_LINEAR_BUF(abd), abd->abd_size);
+ }
+
+ zfs_refcount_destroy(&abd->abd_children);
+ abd_update_linear_stats(abd, ABDSTAT_DECR);
+
+ abd_free_struct(abd);
+}
+
+static void
+abd_free_gang_abd(abd_t *abd)
+{
+ ASSERT(abd_is_gang(abd));
+ abd_t *cabd = list_head(&ABD_GANG(abd).abd_gang_chain);
+
+ while (cabd != NULL) {
+ /*
+ * We must acquire the child ABDs mutex to ensure that if it
+ * is being added to another gang ABD we will set the link
+ * as inactive when removing it from this gang ABD and before
+ * adding it to the other gang ABD.
+ */
+ mutex_enter(&cabd->abd_mtx);
+ ASSERT(list_link_active(&cabd->abd_gang_link));
+ list_remove(&ABD_GANG(abd).abd_gang_chain, cabd);
+ mutex_exit(&cabd->abd_mtx);
+ abd->abd_size -= cabd->abd_size;
+ if (cabd->abd_flags & ABD_FLAG_GANG_FREE) {
+ if (cabd->abd_flags & ABD_FLAG_OWNER)
+ abd_free(cabd);
+ else
+ abd_put(cabd);
+ }
+ cabd = list_head(&ABD_GANG(abd).abd_gang_chain);
+ }
+ ASSERT0(abd->abd_size);
+ list_destroy(&ABD_GANG(abd).abd_gang_chain);
+ zfs_refcount_destroy(&abd->abd_children);
+ abd_free_struct(abd);
+}
+
+/*
+ * Free an ABD. Only use this on ABDs allocated with abd_alloc(),
+ * abd_alloc_linear(), or abd_alloc_gang_abd().
+ */
+void
+abd_free(abd_t *abd)
+{
+ if (abd == NULL)
+ return;
+
+ abd_verify(abd);
+ ASSERT3P(abd->abd_parent, ==, NULL);
+ ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
+ if (abd_is_linear(abd))
+ abd_free_linear(abd);
+ else if (abd_is_gang(abd))
+ abd_free_gang_abd(abd);
+ else
+ abd_free_scatter(abd);
+}
+
+/*
+ * Allocate an ABD of the same format (same metadata flag, same scatterize
+ * setting) as another ABD.
+ */
+abd_t *
+abd_alloc_sametype(abd_t *sabd, size_t size)
+{
+ boolean_t is_metadata = (sabd->abd_flags & ABD_FLAG_META) != 0;
+ if (abd_is_linear(sabd) &&
+ !abd_is_linear_page(sabd)) {
+ return (abd_alloc_linear(size, is_metadata));
+ } else {
+ return (abd_alloc(size, is_metadata));
+ }
+}
+
+
+/*
+ * Create gang ABD that will be the head of a list of ABD's. This is used
+ * to "chain" scatter/gather lists together when constructing aggregated
+ * IO's. To free this abd, abd_free() must be called.
+ */
+abd_t *
+abd_alloc_gang_abd(void)
+{
+ abd_t *abd;
+
+ abd = abd_alloc_struct(0);
+ abd->abd_flags = ABD_FLAG_GANG | ABD_FLAG_OWNER;
+ abd->abd_size = 0;
+ abd->abd_parent = NULL;
+ list_create(&ABD_GANG(abd).abd_gang_chain,
+ sizeof (abd_t), offsetof(abd_t, abd_gang_link));
+ zfs_refcount_create(&abd->abd_children);
+ return (abd);
+}
+
+/*
+ * Add a child gang ABD to a parent gang ABDs chained list.
+ */
+static void
+abd_gang_add_gang(abd_t *pabd, abd_t *cabd, boolean_t free_on_free)
+{
+ ASSERT(abd_is_gang(pabd));
+ ASSERT(abd_is_gang(cabd));
+
+ if (free_on_free) {
+ /*
+ * If the parent is responsible for freeing the child gang
+ * ABD we will just splice the childs children ABD list to
+ * the parents list and immediately free the child gang ABD
+ * struct. The parent gang ABDs children from the child gang
+ * will retain all the free_on_free settings after being
+ * added to the parents list.
+ */
+ pabd->abd_size += cabd->abd_size;
+ list_move_tail(&ABD_GANG(pabd).abd_gang_chain,
+ &ABD_GANG(cabd).abd_gang_chain);
+ ASSERT(list_is_empty(&ABD_GANG(cabd).abd_gang_chain));
+ abd_verify(pabd);
+ abd_free_struct(cabd);
+ } else {
+ for (abd_t *child = list_head(&ABD_GANG(cabd).abd_gang_chain);
+ child != NULL;
+ child = list_next(&ABD_GANG(cabd).abd_gang_chain, child)) {
+ /*
+ * We always pass B_FALSE for free_on_free as it is the
+ * original child gang ABDs responsibilty to determine
+ * if any of its child ABDs should be free'd on the call
+ * to abd_free().
+ */
+ abd_gang_add(pabd, child, B_FALSE);
+ }
+ abd_verify(pabd);
+ }
+}
+
+/*
+ * Add a child ABD to a gang ABD's chained list.
+ */
+void
+abd_gang_add(abd_t *pabd, abd_t *cabd, boolean_t free_on_free)
+{
+ ASSERT(abd_is_gang(pabd));
+ abd_t *child_abd = NULL;
+
+ /*
+ * If the child being added is a gang ABD, we will add the
+ * childs ABDs to the parent gang ABD. This alllows us to account
+ * for the offset correctly in the parent gang ABD.
+ */
+ if (abd_is_gang(cabd)) {
+ ASSERT(!list_link_active(&cabd->abd_gang_link));
+ ASSERT(!list_is_empty(&ABD_GANG(cabd).abd_gang_chain));
+ return (abd_gang_add_gang(pabd, cabd, free_on_free));
+ }
+ ASSERT(!abd_is_gang(cabd));
+
+ /*
+ * In order to verify that an ABD is not already part of
+ * another gang ABD, we must lock the child ABD's abd_mtx
+ * to check its abd_gang_link status. We unlock the abd_mtx
+ * only after it is has been added to a gang ABD, which
+ * will update the abd_gang_link's status. See comment below
+ * for how an ABD can be in multiple gang ABD's simultaneously.
+ */
+ mutex_enter(&cabd->abd_mtx);
+ if (list_link_active(&cabd->abd_gang_link)) {
+ /*
+ * If the child ABD is already part of another
+ * gang ABD then we must allocate a new
+ * ABD to use a separate link. We mark the newly
+ * allocated ABD with ABD_FLAG_GANG_FREE, before
+ * adding it to the gang ABD's list, to make the
+ * gang ABD aware that it is responsible to call
+ * abd_put(). We use abd_get_offset() in order
+ * to just allocate a new ABD but avoid copying the
+ * data over into the newly allocated ABD.
+ *
+ * An ABD may become part of multiple gang ABD's. For
+ * example, when writing ditto bocks, the same ABD
+ * is used to write 2 or 3 locations with 2 or 3
+ * zio_t's. Each of the zio's may be aggregated with
+ * different adjacent zio's. zio aggregation uses gang
+ * zio's, so the single ABD can become part of multiple
+ * gang zio's.
+ *
+ * The ASSERT below is to make sure that if
+ * free_on_free is passed as B_TRUE, the ABD can
+ * not be in multiple gang ABD's. The gang ABD
+ * can not be responsible for cleaning up the child
+ * ABD memory allocation if the ABD can be in
+ * multiple gang ABD's at one time.
+ */
+ ASSERT3B(free_on_free, ==, B_FALSE);
+ child_abd = abd_get_offset(cabd, 0);
+ child_abd->abd_flags |= ABD_FLAG_GANG_FREE;
+ } else {
+ child_abd = cabd;
+ if (free_on_free)
+ child_abd->abd_flags |= ABD_FLAG_GANG_FREE;
+ }
+ ASSERT3P(child_abd, !=, NULL);
+
+ list_insert_tail(&ABD_GANG(pabd).abd_gang_chain, child_abd);
+ mutex_exit(&cabd->abd_mtx);
+ pabd->abd_size += child_abd->abd_size;
+}
+
+/*
+ * Locate the ABD for the supplied offset in the gang ABD.
+ * Return a new offset relative to the returned ABD.
+ */
+abd_t *
+abd_gang_get_offset(abd_t *abd, size_t *off)
+{
+ abd_t *cabd;
+
+ ASSERT(abd_is_gang(abd));
+ ASSERT3U(*off, <, abd->abd_size);
+ for (cabd = list_head(&ABD_GANG(abd).abd_gang_chain); cabd != NULL;
+ cabd = list_next(&ABD_GANG(abd).abd_gang_chain, cabd)) {
+ if (*off >= cabd->abd_size)
+ *off -= cabd->abd_size;
+ else
+ return (cabd);
+ }
+ VERIFY3P(cabd, !=, NULL);
+ return (cabd);
+}
+
+/*
+ * Allocate a new ABD to point to offset off of sabd. It shares the underlying
+ * buffer data with sabd. Use abd_put() to free. sabd must not be freed while
+ * any derived ABDs exist.
+ */
+static abd_t *
+abd_get_offset_impl(abd_t *sabd, size_t off, size_t size)
+{
+ abd_t *abd = NULL;
+
+ abd_verify(sabd);
+ ASSERT3U(off, <=, sabd->abd_size);
+
+ if (abd_is_linear(sabd)) {
+ abd = abd_alloc_struct(0);
+
+ /*
+ * Even if this buf is filesystem metadata, we only track that
+ * if we own the underlying data buffer, which is not true in
+ * this case. Therefore, we don't ever use ABD_FLAG_META here.
+ */
+ abd->abd_flags = ABD_FLAG_LINEAR;
+
+ ABD_LINEAR_BUF(abd) = (char *)ABD_LINEAR_BUF(sabd) + off;
+ } else if (abd_is_gang(sabd)) {
+ size_t left = size;
+ abd = abd_alloc_gang_abd();
+ abd->abd_flags &= ~ABD_FLAG_OWNER;
+ for (abd_t *cabd = abd_gang_get_offset(sabd, &off);
+ cabd != NULL && left > 0;
+ cabd = list_next(&ABD_GANG(sabd).abd_gang_chain, cabd)) {
+ int csize = MIN(left, cabd->abd_size - off);
+
+ abd_t *nabd = abd_get_offset_impl(cabd, off, csize);
+ abd_gang_add(abd, nabd, B_FALSE);
+ left -= csize;
+ off = 0;
+ }
+ ASSERT3U(left, ==, 0);
+ } else {
+ abd = abd_get_offset_scatter(sabd, off);
+ }
+
+ abd->abd_size = size;
+ abd->abd_parent = sabd;
+ zfs_refcount_create(&abd->abd_children);
+ (void) zfs_refcount_add_many(&sabd->abd_children, abd->abd_size, abd);
+ return (abd);
+}
+
+abd_t *
+abd_get_offset(abd_t *sabd, size_t off)
+{
+ size_t size = sabd->abd_size > off ? sabd->abd_size - off : 0;
+ VERIFY3U(size, >, 0);
+ return (abd_get_offset_impl(sabd, off, size));
+}
+
+abd_t *
+abd_get_offset_size(abd_t *sabd, size_t off, size_t size)
+{
+ ASSERT3U(off + size, <=, sabd->abd_size);
+ return (abd_get_offset_impl(sabd, off, size));
+}
+
+/*
+ * Return a size scatter ABD. In order to free the returned
+ * ABD abd_put() must be called.
+ */
+abd_t *
+abd_get_zeros(size_t size)
+{
+ ASSERT3P(abd_zero_scatter, !=, NULL);
+ ASSERT3U(size, <=, SPA_MAXBLOCKSIZE);
+ return (abd_get_offset_size(abd_zero_scatter, 0, size));
+}
+
+/*
+ * Allocate a linear ABD structure for buf. You must free this with abd_put()
+ * since the resulting ABD doesn't own its own buffer.
+ */
+abd_t *
+abd_get_from_buf(void *buf, size_t size)
+{
+ abd_t *abd = abd_alloc_struct(0);
+
+ VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+
+ /*
+ * Even if this buf is filesystem metadata, we only track that if we
+ * own the underlying data buffer, which is not true in this case.
+ * Therefore, we don't ever use ABD_FLAG_META here.
+ */
+ abd->abd_flags = ABD_FLAG_LINEAR;
+ abd->abd_size = size;
+ abd->abd_parent = NULL;
+ zfs_refcount_create(&abd->abd_children);
+
+ ABD_LINEAR_BUF(abd) = buf;
+
+ return (abd);
+}
+
+/*
+ * Get the raw buffer associated with a linear ABD.
+ */
+void *
+abd_to_buf(abd_t *abd)
+{
+ ASSERT(abd_is_linear(abd));
+ abd_verify(abd);
+ return (ABD_LINEAR_BUF(abd));
+}
+
+/*
+ * Borrow a raw buffer from an ABD without copying the contents of the ABD
+ * into the buffer. If the ABD is scattered, this will allocate a raw buffer
+ * whose contents are undefined. To copy over the existing data in the ABD, use
+ * abd_borrow_buf_copy() instead.
+ */
+void *
+abd_borrow_buf(abd_t *abd, size_t n)
+{
+ void *buf;
+ abd_verify(abd);
+ ASSERT3U(abd->abd_size, >=, n);
+ if (abd_is_linear(abd)) {
+ buf = abd_to_buf(abd);
+ } else {
+ buf = zio_buf_alloc(n);
+ }
+ (void) zfs_refcount_add_many(&abd->abd_children, n, buf);
+ return (buf);
+}
+
+void *
+abd_borrow_buf_copy(abd_t *abd, size_t n)
+{
+ void *buf = abd_borrow_buf(abd, n);
+ if (!abd_is_linear(abd)) {
+ abd_copy_to_buf(buf, abd, n);
+ }
+ return (buf);
+}
+
+/*
+ * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will
+ * not change the contents of the ABD and will ASSERT that you didn't modify
+ * the buffer since it was borrowed. If you want any changes you made to buf to
+ * be copied back to abd, use abd_return_buf_copy() instead.
+ */
+void
+abd_return_buf(abd_t *abd, void *buf, size_t n)
+{
+ abd_verify(abd);
+ ASSERT3U(abd->abd_size, >=, n);
+ if (abd_is_linear(abd)) {
+ ASSERT3P(buf, ==, abd_to_buf(abd));
+ } else {
+ ASSERT0(abd_cmp_buf(abd, buf, n));
+ zio_buf_free(buf, n);
+ }
+ (void) zfs_refcount_remove_many(&abd->abd_children, n, buf);
+}
+
+void
+abd_return_buf_copy(abd_t *abd, void *buf, size_t n)
+{
+ if (!abd_is_linear(abd)) {
+ abd_copy_from_buf(abd, buf, n);
+ }
+ abd_return_buf(abd, buf, n);
+}
+
+void
+abd_release_ownership_of_buf(abd_t *abd)
+{
+ ASSERT(abd_is_linear(abd));
+ ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
+
+ /*
+ * abd_free() needs to handle LINEAR_PAGE ABD's specially.
+ * Since that flag does not survive the
+ * abd_release_ownership_of_buf() -> abd_get_from_buf() ->
+ * abd_take_ownership_of_buf() sequence, we don't allow releasing
+ * these "linear but not zio_[data_]buf_alloc()'ed" ABD's.
+ */
+ ASSERT(!abd_is_linear_page(abd));
+
+ abd_verify(abd);
+
+ abd->abd_flags &= ~ABD_FLAG_OWNER;
+ /* Disable this flag since we no longer own the data buffer */
+ abd->abd_flags &= ~ABD_FLAG_META;
+
+ abd_update_linear_stats(abd, ABDSTAT_DECR);
+}
+
+
+/*
+ * Give this ABD ownership of the buffer that it's storing. Can only be used on
+ * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated
+ * with abd_alloc_linear() which subsequently released ownership of their buf
+ * with abd_release_ownership_of_buf().
+ */
+void
+abd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata)
+{
+ ASSERT(abd_is_linear(abd));
+ ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
+ abd_verify(abd);
+
+ abd->abd_flags |= ABD_FLAG_OWNER;
+ if (is_metadata) {
+ abd->abd_flags |= ABD_FLAG_META;
+ }
+
+ abd_update_linear_stats(abd, ABDSTAT_INCR);
+}
+
+/*
+ * Initializes an abd_iter based on whether the abd is a gang ABD
+ * or just a single ABD.
+ */
+static inline abd_t *
+abd_init_abd_iter(abd_t *abd, struct abd_iter *aiter, size_t off)
+{
+ abd_t *cabd = NULL;
+
+ if (abd_is_gang(abd)) {
+ cabd = abd_gang_get_offset(abd, &off);
+ if (cabd) {
+ abd_iter_init(aiter, cabd);
+ abd_iter_advance(aiter, off);
+ }
+ } else {
+ abd_iter_init(aiter, abd);
+ abd_iter_advance(aiter, off);
+ }
+ return (cabd);
+}
+
+/*
+ * Advances an abd_iter. We have to be careful with gang ABD as
+ * advancing could mean that we are at the end of a particular ABD and
+ * must grab the ABD in the gang ABD's list.
+ */
+static inline abd_t *
+abd_advance_abd_iter(abd_t *abd, abd_t *cabd, struct abd_iter *aiter,
+ size_t len)
+{
+ abd_iter_advance(aiter, len);
+ if (abd_is_gang(abd) && abd_iter_at_end(aiter)) {
+ ASSERT3P(cabd, !=, NULL);
+ cabd = list_next(&ABD_GANG(abd).abd_gang_chain, cabd);
+ if (cabd) {
+ abd_iter_init(aiter, cabd);
+ abd_iter_advance(aiter, 0);
+ }
+ }
+ return (cabd);
+}
+
+int
+abd_iterate_func(abd_t *abd, size_t off, size_t size,
+ abd_iter_func_t *func, void *private)
+{
+ int ret = 0;
+ struct abd_iter aiter;
+ boolean_t abd_multi;
+ abd_t *c_abd;
+
+ abd_verify(abd);
+ ASSERT3U(off + size, <=, abd->abd_size);
+
+ abd_multi = abd_is_gang(abd);
+ c_abd = abd_init_abd_iter(abd, &aiter, off);
+
+ while (size > 0) {
+ /* If we are at the end of the gang ABD we are done */
+ if (abd_multi && !c_abd)
+ break;
+
+ abd_iter_map(&aiter);
+
+ size_t len = MIN(aiter.iter_mapsize, size);
+ ASSERT3U(len, >, 0);
+
+ ret = func(aiter.iter_mapaddr, len, private);
+
+ abd_iter_unmap(&aiter);
+
+ if (ret != 0)
+ break;
+
+ size -= len;
+ c_abd = abd_advance_abd_iter(abd, c_abd, &aiter, len);
+ }
+
+ return (ret);
+}
+
+struct buf_arg {
+ void *arg_buf;
+};
+
+static int
+abd_copy_to_buf_off_cb(void *buf, size_t size, void *private)
+{
+ struct buf_arg *ba_ptr = private;
+
+ (void) memcpy(ba_ptr->arg_buf, buf, size);
+ ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
+
+ return (0);
+}
+
+/*
+ * Copy abd to buf. (off is the offset in abd.)
+ */
+void
+abd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size)
+{
+ struct buf_arg ba_ptr = { buf };
+
+ (void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb,
+ &ba_ptr);
+}
+
+static int
+abd_cmp_buf_off_cb(void *buf, size_t size, void *private)
+{
+ int ret;
+ struct buf_arg *ba_ptr = private;
+
+ ret = memcmp(buf, ba_ptr->arg_buf, size);
+ ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
+
+ return (ret);
+}
+
+/*
+ * Compare the contents of abd to buf. (off is the offset in abd.)
+ */
+int
+abd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
+{
+ struct buf_arg ba_ptr = { (void *) buf };
+
+ return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr));
+}
+
+static int
+abd_copy_from_buf_off_cb(void *buf, size_t size, void *private)
+{
+ struct buf_arg *ba_ptr = private;
+
+ (void) memcpy(buf, ba_ptr->arg_buf, size);
+ ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
+
+ return (0);
+}
+
+/*
+ * Copy from buf to abd. (off is the offset in abd.)
+ */
+void
+abd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
+{
+ struct buf_arg ba_ptr = { (void *) buf };
+
+ (void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb,
+ &ba_ptr);
+}
+
+/*ARGSUSED*/
+static int
+abd_zero_off_cb(void *buf, size_t size, void *private)
+{
+ (void) memset(buf, 0, size);
+ return (0);
+}
+
+/*
+ * Zero out the abd from a particular offset to the end.
+ */
+void
+abd_zero_off(abd_t *abd, size_t off, size_t size)
+{
+ (void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL);
+}
+
+/*
+ * Iterate over two ABDs and call func incrementally on the two ABDs' data in
+ * equal-sized chunks (passed to func as raw buffers). func could be called many
+ * times during this iteration.
+ */
+int
+abd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff,
+ size_t size, abd_iter_func2_t *func, void *private)
+{
+ int ret = 0;
+ struct abd_iter daiter, saiter;
+ boolean_t dabd_is_gang_abd, sabd_is_gang_abd;
+ abd_t *c_dabd, *c_sabd;
+
+ abd_verify(dabd);
+ abd_verify(sabd);
+
+ ASSERT3U(doff + size, <=, dabd->abd_size);
+ ASSERT3U(soff + size, <=, sabd->abd_size);
+
+ dabd_is_gang_abd = abd_is_gang(dabd);
+ sabd_is_gang_abd = abd_is_gang(sabd);
+ c_dabd = abd_init_abd_iter(dabd, &daiter, doff);
+ c_sabd = abd_init_abd_iter(sabd, &saiter, soff);
+
+ while (size > 0) {
+ /* if we are at the end of the gang ABD we are done */
+ if ((dabd_is_gang_abd && !c_dabd) ||
+ (sabd_is_gang_abd && !c_sabd))
+ break;
+
+ abd_iter_map(&daiter);
+ abd_iter_map(&saiter);
+
+ size_t dlen = MIN(daiter.iter_mapsize, size);
+ size_t slen = MIN(saiter.iter_mapsize, size);
+ size_t len = MIN(dlen, slen);
+ ASSERT(dlen > 0 || slen > 0);
+
+ ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len,
+ private);
+
+ abd_iter_unmap(&saiter);
+ abd_iter_unmap(&daiter);
+
+ if (ret != 0)
+ break;
+
+ size -= len;
+ c_dabd =
+ abd_advance_abd_iter(dabd, c_dabd, &daiter, len);
+ c_sabd =
+ abd_advance_abd_iter(sabd, c_sabd, &saiter, len);
+ }
+
+ return (ret);
+}
+
+/*ARGSUSED*/
+static int
+abd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private)
+{
+ (void) memcpy(dbuf, sbuf, size);
+ return (0);
+}
+
+/*
+ * Copy from sabd to dabd starting from soff and doff.
+ */
+void
+abd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size)
+{
+ (void) abd_iterate_func2(dabd, sabd, doff, soff, size,
+ abd_copy_off_cb, NULL);
+}
+
+/*ARGSUSED*/
+static int
+abd_cmp_cb(void *bufa, void *bufb, size_t size, void *private)
+{
+ return (memcmp(bufa, bufb, size));
+}
+
+/*
+ * Compares the contents of two ABDs.
+ */
+int
+abd_cmp(abd_t *dabd, abd_t *sabd)
+{
+ ASSERT3U(dabd->abd_size, ==, sabd->abd_size);
+ return (abd_iterate_func2(dabd, sabd, 0, 0, dabd->abd_size,
+ abd_cmp_cb, NULL));
+}
+
+/*
+ * Iterate over code ABDs and a data ABD and call @func_raidz_gen.
+ *
+ * @cabds parity ABDs, must have equal size
+ * @dabd data ABD. Can be NULL (in this case @dsize = 0)
+ * @func_raidz_gen should be implemented so that its behaviour
+ * is the same when taking linear and when taking scatter
+ */
+void
+abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
+ ssize_t csize, ssize_t dsize, const unsigned parity,
+ void (*func_raidz_gen)(void **, const void *, size_t, size_t))
+{
+ int i;
+ ssize_t len, dlen;
+ struct abd_iter caiters[3];
+ struct abd_iter daiter = {0};
+ void *caddrs[3];
+ unsigned long flags __maybe_unused = 0;
+ abd_t *c_cabds[3];
+ abd_t *c_dabd = NULL;
+ boolean_t cabds_is_gang_abd[3];
+ boolean_t dabd_is_gang_abd = B_FALSE;
+
+ ASSERT3U(parity, <=, 3);
+
+ for (i = 0; i < parity; i++) {
+ cabds_is_gang_abd[i] = abd_is_gang(cabds[i]);
+ c_cabds[i] = abd_init_abd_iter(cabds[i], &caiters[i], 0);
+ }
+
+ if (dabd) {
+ dabd_is_gang_abd = abd_is_gang(dabd);
+ c_dabd = abd_init_abd_iter(dabd, &daiter, 0);
+ }
+
+ ASSERT3S(dsize, >=, 0);
+
+ abd_enter_critical(flags);
+ while (csize > 0) {
+ /* if we are at the end of the gang ABD we are done */
+ if (dabd_is_gang_abd && !c_dabd)
+ break;
+
+ for (i = 0; i < parity; i++) {
+ /*
+ * If we are at the end of the gang ABD we are
+ * done.
+ */
+ if (cabds_is_gang_abd[i] && !c_cabds[i])
+ break;
+ abd_iter_map(&caiters[i]);
+ caddrs[i] = caiters[i].iter_mapaddr;
+ }
+
+ len = csize;
+
+ if (dabd && dsize > 0)
+ abd_iter_map(&daiter);
+
+ switch (parity) {
+ case 3:
+ len = MIN(caiters[2].iter_mapsize, len);
+ /* falls through */
+ case 2:
+ len = MIN(caiters[1].iter_mapsize, len);
+ /* falls through */
+ case 1:
+ len = MIN(caiters[0].iter_mapsize, len);
+ }
+
+ /* must be progressive */
+ ASSERT3S(len, >, 0);
+
+ if (dabd && dsize > 0) {
+ /* this needs precise iter.length */
+ len = MIN(daiter.iter_mapsize, len);
+ dlen = len;
+ } else
+ dlen = 0;
+
+ /* must be progressive */
+ ASSERT3S(len, >, 0);
+ /*
+ * The iterated function likely will not do well if each
+ * segment except the last one is not multiple of 512 (raidz).
+ */
+ ASSERT3U(((uint64_t)len & 511ULL), ==, 0);
+
+ func_raidz_gen(caddrs, daiter.iter_mapaddr, len, dlen);
+
+ for (i = parity-1; i >= 0; i--) {
+ abd_iter_unmap(&caiters[i]);
+ c_cabds[i] =
+ abd_advance_abd_iter(cabds[i], c_cabds[i],
+ &caiters[i], len);
+ }
+
+ if (dabd && dsize > 0) {
+ abd_iter_unmap(&daiter);
+ c_dabd =
+ abd_advance_abd_iter(dabd, c_dabd, &daiter,
+ dlen);
+ dsize -= dlen;
+ }
+
+ csize -= len;
+
+ ASSERT3S(dsize, >=, 0);
+ ASSERT3S(csize, >=, 0);
+ }
+ abd_exit_critical(flags);
+}
+
+/*
+ * Iterate over code ABDs and data reconstruction target ABDs and call
+ * @func_raidz_rec. Function maps at most 6 pages atomically.
+ *
+ * @cabds parity ABDs, must have equal size
+ * @tabds rec target ABDs, at most 3
+ * @tsize size of data target columns
+ * @func_raidz_rec expects syndrome data in target columns. Function
+ * reconstructs data and overwrites target columns.
+ */
+void
+abd_raidz_rec_iterate(abd_t **cabds, abd_t **tabds,
+ ssize_t tsize, const unsigned parity,
+ void (*func_raidz_rec)(void **t, const size_t tsize, void **c,
+ const unsigned *mul),
+ const unsigned *mul)
+{
+ int i;
+ ssize_t len;
+ struct abd_iter citers[3];
+ struct abd_iter xiters[3];
+ void *caddrs[3], *xaddrs[3];
+ unsigned long flags __maybe_unused = 0;
+ boolean_t cabds_is_gang_abd[3];
+ boolean_t tabds_is_gang_abd[3];
+ abd_t *c_cabds[3];
+ abd_t *c_tabds[3];
+
+ ASSERT3U(parity, <=, 3);
+
+ for (i = 0; i < parity; i++) {
+ cabds_is_gang_abd[i] = abd_is_gang(cabds[i]);
+ tabds_is_gang_abd[i] = abd_is_gang(tabds[i]);
+ c_cabds[i] =
+ abd_init_abd_iter(cabds[i], &citers[i], 0);
+ c_tabds[i] =
+ abd_init_abd_iter(tabds[i], &xiters[i], 0);
+ }
+
+ abd_enter_critical(flags);
+ while (tsize > 0) {
+
+ for (i = 0; i < parity; i++) {
+ /*
+ * If we are at the end of the gang ABD we
+ * are done.
+ */
+ if (cabds_is_gang_abd[i] && !c_cabds[i])
+ break;
+ if (tabds_is_gang_abd[i] && !c_tabds[i])
+ break;
+ abd_iter_map(&citers[i]);
+ abd_iter_map(&xiters[i]);
+ caddrs[i] = citers[i].iter_mapaddr;
+ xaddrs[i] = xiters[i].iter_mapaddr;
+ }
+
+ len = tsize;
+ switch (parity) {
+ case 3:
+ len = MIN(xiters[2].iter_mapsize, len);
+ len = MIN(citers[2].iter_mapsize, len);
+ /* falls through */
+ case 2:
+ len = MIN(xiters[1].iter_mapsize, len);
+ len = MIN(citers[1].iter_mapsize, len);
+ /* falls through */
+ case 1:
+ len = MIN(xiters[0].iter_mapsize, len);
+ len = MIN(citers[0].iter_mapsize, len);
+ }
+ /* must be progressive */
+ ASSERT3S(len, >, 0);
+ /*
+ * The iterated function likely will not do well if each
+ * segment except the last one is not multiple of 512 (raidz).
+ */
+ ASSERT3U(((uint64_t)len & 511ULL), ==, 0);
+
+ func_raidz_rec(xaddrs, len, caddrs, mul);
+
+ for (i = parity-1; i >= 0; i--) {
+ abd_iter_unmap(&xiters[i]);
+ abd_iter_unmap(&citers[i]);
+ c_tabds[i] =
+ abd_advance_abd_iter(tabds[i], c_tabds[i],
+ &xiters[i], len);
+ c_cabds[i] =
+ abd_advance_abd_iter(cabds[i], c_cabds[i],
+ &citers[i], len);
+ }
+
+ tsize -= len;
+ ASSERT3S(tsize, >=, 0);
+ }
+ abd_exit_critical(flags);
+}
diff --git a/sys/contrib/openzfs/module/zfs/aggsum.c b/sys/contrib/openzfs/module/zfs/aggsum.c
new file mode 100644
index 000000000000..a2fec27744e1
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/aggsum.c
@@ -0,0 +1,237 @@
+/*
+ * CDDL HEADER START
+ *
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source. A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2017, 2018 by Delphix. All rights reserved.
+ */
+
+#include <sys/zfs_context.h>
+#include <sys/aggsum.h>
+
+/*
+ * Aggregate-sum counters are a form of fanned-out counter, used when atomic
+ * instructions on a single field cause enough CPU cache line contention to
+ * slow system performance. Due to their increased overhead and the expense
+ * involved with precisely reading from them, they should only be used in cases
+ * where the write rate (increment/decrement) is much higher than the read rate
+ * (get value).
+ *
+ * Aggregate sum counters are comprised of two basic parts, the core and the
+ * buckets. The core counter contains a lock for the entire counter, as well
+ * as the current upper and lower bounds on the value of the counter. The
+ * aggsum_bucket structure contains a per-bucket lock to protect the contents of
+ * the bucket, the current amount that this bucket has changed from the global
+ * counter (called the delta), and the amount of increment and decrement we have
+ * "borrowed" from the core counter.
+ *
+ * The basic operation of an aggsum is simple. Threads that wish to modify the
+ * counter will modify one bucket's counter (determined by their current CPU, to
+ * help minimize lock and cache contention). If the bucket already has
+ * sufficient capacity borrowed from the core structure to handle their request,
+ * they simply modify the delta and return. If the bucket does not, we clear
+ * the bucket's current state (to prevent the borrowed amounts from getting too
+ * large), and borrow more from the core counter. Borrowing is done by adding to
+ * the upper bound (or subtracting from the lower bound) of the core counter,
+ * and setting the borrow value for the bucket to the amount added (or
+ * subtracted). Clearing the bucket is the opposite; we add the current delta
+ * to both the lower and upper bounds of the core counter, subtract the borrowed
+ * incremental from the upper bound, and add the borrowed decrement from the
+ * lower bound. Note that only borrowing and clearing require access to the
+ * core counter; since all other operations access CPU-local resources,
+ * performance can be much higher than a traditional counter.
+ *
+ * Threads that wish to read from the counter have a slightly more challenging
+ * task. It is fast to determine the upper and lower bounds of the aggum; this
+ * does not require grabbing any locks. This suffices for cases where an
+ * approximation of the aggsum's value is acceptable. However, if one needs to
+ * know whether some specific value is above or below the current value in the
+ * aggsum, they invoke aggsum_compare(). This function operates by repeatedly
+ * comparing the target value to the upper and lower bounds of the aggsum, and
+ * then clearing a bucket. This proceeds until the target is outside of the
+ * upper and lower bounds and we return a response, or the last bucket has been
+ * cleared and we know that the target is equal to the aggsum's value. Finally,
+ * the most expensive operation is determining the precise value of the aggsum.
+ * To do this, we clear every bucket and then return the upper bound (which must
+ * be equal to the lower bound). What makes aggsum_compare() and aggsum_value()
+ * expensive is clearing buckets. This involves grabbing the global lock
+ * (serializing against themselves and borrow operations), grabbing a bucket's
+ * lock (preventing threads on those CPUs from modifying their delta), and
+ * zeroing out the borrowed value (forcing that thread to borrow on its next
+ * request, which will also be expensive). This is what makes aggsums well
+ * suited for write-many read-rarely operations.
+ */
+
+/*
+ * We will borrow aggsum_borrow_multiplier times the current request, so we will
+ * have to get the as_lock approximately every aggsum_borrow_multiplier calls to
+ * aggsum_delta().
+ */
+static uint_t aggsum_borrow_multiplier = 10;
+
+void
+aggsum_init(aggsum_t *as, uint64_t value)
+{
+ bzero(as, sizeof (*as));
+ as->as_lower_bound = as->as_upper_bound = value;
+ mutex_init(&as->as_lock, NULL, MUTEX_DEFAULT, NULL);
+ as->as_numbuckets = boot_ncpus;
+ as->as_buckets = kmem_zalloc(boot_ncpus * sizeof (aggsum_bucket_t),
+ KM_SLEEP);
+ for (int i = 0; i < as->as_numbuckets; i++) {
+ mutex_init(&as->as_buckets[i].asc_lock,
+ NULL, MUTEX_DEFAULT, NULL);
+ }
+}
+
+void
+aggsum_fini(aggsum_t *as)
+{
+ for (int i = 0; i < as->as_numbuckets; i++)
+ mutex_destroy(&as->as_buckets[i].asc_lock);
+ kmem_free(as->as_buckets, as->as_numbuckets * sizeof (aggsum_bucket_t));
+ mutex_destroy(&as->as_lock);
+}
+
+int64_t
+aggsum_lower_bound(aggsum_t *as)
+{
+ return (as->as_lower_bound);
+}
+
+int64_t
+aggsum_upper_bound(aggsum_t *as)
+{
+ return (as->as_upper_bound);
+}
+
+static void
+aggsum_flush_bucket(aggsum_t *as, struct aggsum_bucket *asb)
+{
+ ASSERT(MUTEX_HELD(&as->as_lock));
+ ASSERT(MUTEX_HELD(&asb->asc_lock));
+
+ /*
+ * We use atomic instructions for this because we read the upper and
+ * lower bounds without the lock, so we need stores to be atomic.
+ */
+ atomic_add_64((volatile uint64_t *)&as->as_lower_bound,
+ asb->asc_delta + asb->asc_borrowed);
+ atomic_add_64((volatile uint64_t *)&as->as_upper_bound,
+ asb->asc_delta - asb->asc_borrowed);
+ asb->asc_delta = 0;
+ asb->asc_borrowed = 0;
+}
+
+uint64_t
+aggsum_value(aggsum_t *as)
+{
+ int64_t rv;
+
+ mutex_enter(&as->as_lock);
+ if (as->as_lower_bound == as->as_upper_bound) {
+ rv = as->as_lower_bound;
+ for (int i = 0; i < as->as_numbuckets; i++) {
+ ASSERT0(as->as_buckets[i].asc_delta);
+ ASSERT0(as->as_buckets[i].asc_borrowed);
+ }
+ mutex_exit(&as->as_lock);
+ return (rv);
+ }
+ for (int i = 0; i < as->as_numbuckets; i++) {
+ struct aggsum_bucket *asb = &as->as_buckets[i];
+ mutex_enter(&asb->asc_lock);
+ aggsum_flush_bucket(as, asb);
+ mutex_exit(&asb->asc_lock);
+ }
+ VERIFY3U(as->as_lower_bound, ==, as->as_upper_bound);
+ rv = as->as_lower_bound;
+ mutex_exit(&as->as_lock);
+
+ return (rv);
+}
+
+void
+aggsum_add(aggsum_t *as, int64_t delta)
+{
+ struct aggsum_bucket *asb;
+ int64_t borrow;
+
+ kpreempt_disable();
+ asb = &as->as_buckets[CPU_SEQID % as->as_numbuckets];
+ kpreempt_enable();
+
+ /* Try fast path if we already borrowed enough before. */
+ mutex_enter(&asb->asc_lock);
+ if (asb->asc_delta + delta <= (int64_t)asb->asc_borrowed &&
+ asb->asc_delta + delta >= -(int64_t)asb->asc_borrowed) {
+ asb->asc_delta += delta;
+ mutex_exit(&asb->asc_lock);
+ return;
+ }
+ mutex_exit(&asb->asc_lock);
+
+ /*
+ * We haven't borrowed enough. Take the global lock and borrow
+ * considering what is requested now and what we borrowed before.
+ */
+ borrow = (delta < 0 ? -delta : delta) * aggsum_borrow_multiplier;
+ mutex_enter(&as->as_lock);
+ mutex_enter(&asb->asc_lock);
+ delta += asb->asc_delta;
+ asb->asc_delta = 0;
+ if (borrow >= asb->asc_borrowed)
+ borrow -= asb->asc_borrowed;
+ else
+ borrow = (borrow - (int64_t)asb->asc_borrowed) / 4;
+ asb->asc_borrowed += borrow;
+ atomic_add_64((volatile uint64_t *)&as->as_lower_bound,
+ delta - borrow);
+ atomic_add_64((volatile uint64_t *)&as->as_upper_bound,
+ delta + borrow);
+ mutex_exit(&asb->asc_lock);
+ mutex_exit(&as->as_lock);
+}
+
+/*
+ * Compare the aggsum value to target efficiently. Returns -1 if the value
+ * represented by the aggsum is less than target, 1 if it's greater, and 0 if
+ * they are equal.
+ */
+int
+aggsum_compare(aggsum_t *as, uint64_t target)
+{
+ if (as->as_upper_bound < target)
+ return (-1);
+ if (as->as_lower_bound > target)
+ return (1);
+ mutex_enter(&as->as_lock);
+ for (int i = 0; i < as->as_numbuckets; i++) {
+ struct aggsum_bucket *asb = &as->as_buckets[i];
+ mutex_enter(&asb->asc_lock);
+ aggsum_flush_bucket(as, asb);
+ mutex_exit(&asb->asc_lock);
+ if (as->as_upper_bound < target) {
+ mutex_exit(&as->as_lock);
+ return (-1);
+ }
+ if (as->as_lower_bound > target) {
+ mutex_exit(&as->as_lock);
+ return (1);
+ }
+ }
+ VERIFY3U(as->as_lower_bound, ==, as->as_upper_bound);
+ ASSERT3U(as->as_lower_bound, ==, target);
+ mutex_exit(&as->as_lock);
+ return (0);
+}
diff --git a/sys/contrib/openzfs/module/zfs/arc.c b/sys/contrib/openzfs/module/zfs/arc.c
new file mode 100644
index 000000000000..70565cc25011
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/arc.c
@@ -0,0 +1,10582 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, Joyent, Inc.
+ * Copyright (c) 2011, 2019, Delphix. All rights reserved.
+ * Copyright (c) 2014, Saso Kiselkov. All rights reserved.
+ * Copyright (c) 2017, Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2019, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
+ * Copyright (c) 2020, George Amanakis. All rights reserved.
+ * Copyright (c) 2019, Klara Inc.
+ * Copyright (c) 2019, Allan Jude
+ * Copyright (c) 2020, The FreeBSD Foundation [1]
+ *
+ * [1] Portions of this software were developed by Allan Jude
+ * under sponsorship from the FreeBSD Foundation.
+ */
+
+/*
+ * DVA-based Adjustable Replacement Cache
+ *
+ * While much of the theory of operation used here is
+ * based on the self-tuning, low overhead replacement cache
+ * presented by Megiddo and Modha at FAST 2003, there are some
+ * significant differences:
+ *
+ * 1. The Megiddo and Modha model assumes any page is evictable.
+ * Pages in its cache cannot be "locked" into memory. This makes
+ * the eviction algorithm simple: evict the last page in the list.
+ * This also make the performance characteristics easy to reason
+ * about. Our cache is not so simple. At any given moment, some
+ * subset of the blocks in the cache are un-evictable because we
+ * have handed out a reference to them. Blocks are only evictable
+ * when there are no external references active. This makes
+ * eviction far more problematic: we choose to evict the evictable
+ * blocks that are the "lowest" in the list.
+ *
+ * There are times when it is not possible to evict the requested
+ * space. In these circumstances we are unable to adjust the cache
+ * size. To prevent the cache growing unbounded at these times we
+ * implement a "cache throttle" that slows the flow of new data
+ * into the cache until we can make space available.
+ *
+ * 2. The Megiddo and Modha model assumes a fixed cache size.
+ * Pages are evicted when the cache is full and there is a cache
+ * miss. Our model has a variable sized cache. It grows with
+ * high use, but also tries to react to memory pressure from the
+ * operating system: decreasing its size when system memory is
+ * tight.
+ *
+ * 3. The Megiddo and Modha model assumes a fixed page size. All
+ * elements of the cache are therefore exactly the same size. So
+ * when adjusting the cache size following a cache miss, its simply
+ * a matter of choosing a single page to evict. In our model, we
+ * have variable sized cache blocks (ranging from 512 bytes to
+ * 128K bytes). We therefore choose a set of blocks to evict to make
+ * space for a cache miss that approximates as closely as possible
+ * the space used by the new block.
+ *
+ * See also: "ARC: A Self-Tuning, Low Overhead Replacement Cache"
+ * by N. Megiddo & D. Modha, FAST 2003
+ */
+
+/*
+ * The locking model:
+ *
+ * A new reference to a cache buffer can be obtained in two
+ * ways: 1) via a hash table lookup using the DVA as a key,
+ * or 2) via one of the ARC lists. The arc_read() interface
+ * uses method 1, while the internal ARC algorithms for
+ * adjusting the cache use method 2. We therefore provide two
+ * types of locks: 1) the hash table lock array, and 2) the
+ * ARC list locks.
+ *
+ * Buffers do not have their own mutexes, rather they rely on the
+ * hash table mutexes for the bulk of their protection (i.e. most
+ * fields in the arc_buf_hdr_t are protected by these mutexes).
+ *
+ * buf_hash_find() returns the appropriate mutex (held) when it
+ * locates the requested buffer in the hash table. It returns
+ * NULL for the mutex if the buffer was not in the table.
+ *
+ * buf_hash_remove() expects the appropriate hash mutex to be
+ * already held before it is invoked.
+ *
+ * Each ARC state also has a mutex which is used to protect the
+ * buffer list associated with the state. When attempting to
+ * obtain a hash table lock while holding an ARC list lock you
+ * must use: mutex_tryenter() to avoid deadlock. Also note that
+ * the active state mutex must be held before the ghost state mutex.
+ *
+ * It as also possible to register a callback which is run when the
+ * arc_meta_limit is reached and no buffers can be safely evicted. In
+ * this case the arc user should drop a reference on some arc buffers so
+ * they can be reclaimed and the arc_meta_limit honored. For example,
+ * when using the ZPL each dentry holds a references on a znode. These
+ * dentries must be pruned before the arc buffer holding the znode can
+ * be safely evicted.
+ *
+ * Note that the majority of the performance stats are manipulated
+ * with atomic operations.
+ *
+ * The L2ARC uses the l2ad_mtx on each vdev for the following:
+ *
+ * - L2ARC buflist creation
+ * - L2ARC buflist eviction
+ * - L2ARC write completion, which walks L2ARC buflists
+ * - ARC header destruction, as it removes from L2ARC buflists
+ * - ARC header release, as it removes from L2ARC buflists
+ */
+
+/*
+ * ARC operation:
+ *
+ * Every block that is in the ARC is tracked by an arc_buf_hdr_t structure.
+ * This structure can point either to a block that is still in the cache or to
+ * one that is only accessible in an L2 ARC device, or it can provide
+ * information about a block that was recently evicted. If a block is
+ * only accessible in the L2ARC, then the arc_buf_hdr_t only has enough
+ * information to retrieve it from the L2ARC device. This information is
+ * stored in the l2arc_buf_hdr_t sub-structure of the arc_buf_hdr_t. A block
+ * that is in this state cannot access the data directly.
+ *
+ * Blocks that are actively being referenced or have not been evicted
+ * are cached in the L1ARC. The L1ARC (l1arc_buf_hdr_t) is a structure within
+ * the arc_buf_hdr_t that will point to the data block in memory. A block can
+ * only be read by a consumer if it has an l1arc_buf_hdr_t. The L1ARC
+ * caches data in two ways -- in a list of ARC buffers (arc_buf_t) and
+ * also in the arc_buf_hdr_t's private physical data block pointer (b_pabd).
+ *
+ * The L1ARC's data pointer may or may not be uncompressed. The ARC has the
+ * ability to store the physical data (b_pabd) associated with the DVA of the
+ * arc_buf_hdr_t. Since the b_pabd is a copy of the on-disk physical block,
+ * it will match its on-disk compression characteristics. This behavior can be
+ * disabled by setting 'zfs_compressed_arc_enabled' to B_FALSE. When the
+ * compressed ARC functionality is disabled, the b_pabd will point to an
+ * uncompressed version of the on-disk data.
+ *
+ * Data in the L1ARC is not accessed by consumers of the ARC directly. Each
+ * arc_buf_hdr_t can have multiple ARC buffers (arc_buf_t) which reference it.
+ * Each ARC buffer (arc_buf_t) is being actively accessed by a specific ARC
+ * consumer. The ARC will provide references to this data and will keep it
+ * cached until it is no longer in use. The ARC caches only the L1ARC's physical
+ * data block and will evict any arc_buf_t that is no longer referenced. The
+ * amount of memory consumed by the arc_buf_ts' data buffers can be seen via the
+ * "overhead_size" kstat.
+ *
+ * Depending on the consumer, an arc_buf_t can be requested in uncompressed or
+ * compressed form. The typical case is that consumers will want uncompressed
+ * data, and when that happens a new data buffer is allocated where the data is
+ * decompressed for them to use. Currently the only consumer who wants
+ * compressed arc_buf_t's is "zfs send", when it streams data exactly as it
+ * exists on disk. When this happens, the arc_buf_t's data buffer is shared
+ * with the arc_buf_hdr_t.
+ *
+ * Here is a diagram showing an arc_buf_hdr_t referenced by two arc_buf_t's. The
+ * first one is owned by a compressed send consumer (and therefore references
+ * the same compressed data buffer as the arc_buf_hdr_t) and the second could be
+ * used by any other consumer (and has its own uncompressed copy of the data
+ * buffer).
+ *
+ * arc_buf_hdr_t
+ * +-----------+
+ * | fields |
+ * | common to |
+ * | L1- and |
+ * | L2ARC |
+ * +-----------+
+ * | l2arc_buf_hdr_t
+ * | |
+ * +-----------+
+ * | l1arc_buf_hdr_t
+ * | | arc_buf_t
+ * | b_buf +------------>+-----------+ arc_buf_t
+ * | b_pabd +-+ |b_next +---->+-----------+
+ * +-----------+ | |-----------| |b_next +-->NULL
+ * | |b_comp = T | +-----------+
+ * | |b_data +-+ |b_comp = F |
+ * | +-----------+ | |b_data +-+
+ * +->+------+ | +-----------+ |
+ * compressed | | | |
+ * data | |<--------------+ | uncompressed
+ * +------+ compressed, | data
+ * shared +-->+------+
+ * data | |
+ * | |
+ * +------+
+ *
+ * When a consumer reads a block, the ARC must first look to see if the
+ * arc_buf_hdr_t is cached. If the hdr is cached then the ARC allocates a new
+ * arc_buf_t and either copies uncompressed data into a new data buffer from an
+ * existing uncompressed arc_buf_t, decompresses the hdr's b_pabd buffer into a
+ * new data buffer, or shares the hdr's b_pabd buffer, depending on whether the
+ * hdr is compressed and the desired compression characteristics of the
+ * arc_buf_t consumer. If the arc_buf_t ends up sharing data with the
+ * arc_buf_hdr_t and both of them are uncompressed then the arc_buf_t must be
+ * the last buffer in the hdr's b_buf list, however a shared compressed buf can
+ * be anywhere in the hdr's list.
+ *
+ * The diagram below shows an example of an uncompressed ARC hdr that is
+ * sharing its data with an arc_buf_t (note that the shared uncompressed buf is
+ * the last element in the buf list):
+ *
+ * arc_buf_hdr_t
+ * +-----------+
+ * | |
+ * | |
+ * | |
+ * +-----------+
+ * l2arc_buf_hdr_t| |
+ * | |
+ * +-----------+
+ * l1arc_buf_hdr_t| |
+ * | | arc_buf_t (shared)
+ * | b_buf +------------>+---------+ arc_buf_t
+ * | | |b_next +---->+---------+
+ * | b_pabd +-+ |---------| |b_next +-->NULL
+ * +-----------+ | | | +---------+
+ * | |b_data +-+ | |
+ * | +---------+ | |b_data +-+
+ * +->+------+ | +---------+ |
+ * | | | |
+ * uncompressed | | | |
+ * data +------+ | |
+ * ^ +->+------+ |
+ * | uncompressed | | |
+ * | data | | |
+ * | +------+ |
+ * +---------------------------------+
+ *
+ * Writing to the ARC requires that the ARC first discard the hdr's b_pabd
+ * since the physical block is about to be rewritten. The new data contents
+ * will be contained in the arc_buf_t. As the I/O pipeline performs the write,
+ * it may compress the data before writing it to disk. The ARC will be called
+ * with the transformed data and will bcopy the transformed on-disk block into
+ * a newly allocated b_pabd. Writes are always done into buffers which have
+ * either been loaned (and hence are new and don't have other readers) or
+ * buffers which have been released (and hence have their own hdr, if there
+ * were originally other readers of the buf's original hdr). This ensures that
+ * the ARC only needs to update a single buf and its hdr after a write occurs.
+ *
+ * When the L2ARC is in use, it will also take advantage of the b_pabd. The
+ * L2ARC will always write the contents of b_pabd to the L2ARC. This means
+ * that when compressed ARC is enabled that the L2ARC blocks are identical
+ * to the on-disk block in the main data pool. This provides a significant
+ * advantage since the ARC can leverage the bp's checksum when reading from the
+ * L2ARC to determine if the contents are valid. However, if the compressed
+ * ARC is disabled, then the L2ARC's block must be transformed to look
+ * like the physical block in the main data pool before comparing the
+ * checksum and determining its validity.
+ *
+ * The L1ARC has a slightly different system for storing encrypted data.
+ * Raw (encrypted + possibly compressed) data has a few subtle differences from
+ * data that is just compressed. The biggest difference is that it is not
+ * possible to decrypt encrypted data (or vice-versa) if the keys aren't loaded.
+ * The other difference is that encryption cannot be treated as a suggestion.
+ * If a caller would prefer compressed data, but they actually wind up with
+ * uncompressed data the worst thing that could happen is there might be a
+ * performance hit. If the caller requests encrypted data, however, we must be
+ * sure they actually get it or else secret information could be leaked. Raw
+ * data is stored in hdr->b_crypt_hdr.b_rabd. An encrypted header, therefore,
+ * may have both an encrypted version and a decrypted version of its data at
+ * once. When a caller needs a raw arc_buf_t, it is allocated and the data is
+ * copied out of this header. To avoid complications with b_pabd, raw buffers
+ * cannot be shared.
+ */
+
+#include <sys/spa.h>
+#include <sys/zio.h>
+#include <sys/spa_impl.h>
+#include <sys/zio_compress.h>
+#include <sys/zio_checksum.h>
+#include <sys/zfs_context.h>
+#include <sys/arc.h>
+#include <sys/zfs_refcount.h>
+#include <sys/vdev.h>
+#include <sys/vdev_impl.h>
+#include <sys/dsl_pool.h>
+#include <sys/zio_checksum.h>
+#include <sys/multilist.h>
+#include <sys/abd.h>
+#include <sys/zil.h>
+#include <sys/fm/fs/zfs.h>
+#include <sys/callb.h>
+#include <sys/kstat.h>
+#include <sys/zthr.h>
+#include <zfs_fletcher.h>
+#include <sys/arc_impl.h>
+#include <sys/trace_zfs.h>
+#include <sys/aggsum.h>
+#include <cityhash.h>
+#include <sys/vdev_trim.h>
+
+#ifndef _KERNEL
+/* set with ZFS_DEBUG=watch, to enable watchpoints on frozen buffers */
+boolean_t arc_watch = B_FALSE;
+#endif
+
+/*
+ * This thread's job is to keep enough free memory in the system, by
+ * calling arc_kmem_reap_soon() plus arc_reduce_target_size(), which improves
+ * arc_available_memory().
+ */
+static zthr_t *arc_reap_zthr;
+
+/*
+ * This thread's job is to keep arc_size under arc_c, by calling
+ * arc_evict(), which improves arc_is_overflowing().
+ */
+static zthr_t *arc_evict_zthr;
+
+static kmutex_t arc_evict_lock;
+static boolean_t arc_evict_needed = B_FALSE;
+
+/*
+ * Count of bytes evicted since boot.
+ */
+static uint64_t arc_evict_count;
+
+/*
+ * List of arc_evict_waiter_t's, representing threads waiting for the
+ * arc_evict_count to reach specific values.
+ */
+static list_t arc_evict_waiters;
+
+/*
+ * When arc_is_overflowing(), arc_get_data_impl() waits for this percent of
+ * the requested amount of data to be evicted. For example, by default for
+ * every 2KB that's evicted, 1KB of it may be "reused" by a new allocation.
+ * Since this is above 100%, it ensures that progress is made towards getting
+ * arc_size under arc_c. Since this is finite, it ensures that allocations
+ * can still happen, even during the potentially long time that arc_size is
+ * more than arc_c.
+ */
+int zfs_arc_eviction_pct = 200;
+
+/*
+ * The number of headers to evict in arc_evict_state_impl() before
+ * dropping the sublist lock and evicting from another sublist. A lower
+ * value means we're more likely to evict the "correct" header (i.e. the
+ * oldest header in the arc state), but comes with higher overhead
+ * (i.e. more invocations of arc_evict_state_impl()).
+ */
+int zfs_arc_evict_batch_limit = 10;
+
+/* number of seconds before growing cache again */
+int arc_grow_retry = 5;
+
+/*
+ * Minimum time between calls to arc_kmem_reap_soon().
+ */
+int arc_kmem_cache_reap_retry_ms = 1000;
+
+/* shift of arc_c for calculating overflow limit in arc_get_data_impl */
+int zfs_arc_overflow_shift = 8;
+
+/* shift of arc_c for calculating both min and max arc_p */
+int arc_p_min_shift = 4;
+
+/* log2(fraction of arc to reclaim) */
+int arc_shrink_shift = 7;
+
+/* percent of pagecache to reclaim arc to */
+#ifdef _KERNEL
+uint_t zfs_arc_pc_percent = 0;
+#endif
+
+/*
+ * log2(fraction of ARC which must be free to allow growing).
+ * I.e. If there is less than arc_c >> arc_no_grow_shift free memory,
+ * when reading a new block into the ARC, we will evict an equal-sized block
+ * from the ARC.
+ *
+ * This must be less than arc_shrink_shift, so that when we shrink the ARC,
+ * we will still not allow it to grow.
+ */
+int arc_no_grow_shift = 5;
+
+
+/*
+ * minimum lifespan of a prefetch block in clock ticks
+ * (initialized in arc_init())
+ */
+static int arc_min_prefetch_ms;
+static int arc_min_prescient_prefetch_ms;
+
+/*
+ * If this percent of memory is free, don't throttle.
+ */
+int arc_lotsfree_percent = 10;
+
+/*
+ * The arc has filled available memory and has now warmed up.
+ */
+boolean_t arc_warm;
+
+/*
+ * These tunables are for performance analysis.
+ */
+unsigned long zfs_arc_max = 0;
+unsigned long zfs_arc_min = 0;
+unsigned long zfs_arc_meta_limit = 0;
+unsigned long zfs_arc_meta_min = 0;
+unsigned long zfs_arc_dnode_limit = 0;
+unsigned long zfs_arc_dnode_reduce_percent = 10;
+int zfs_arc_grow_retry = 0;
+int zfs_arc_shrink_shift = 0;
+int zfs_arc_p_min_shift = 0;
+int zfs_arc_average_blocksize = 8 * 1024; /* 8KB */
+
+/*
+ * ARC dirty data constraints for arc_tempreserve_space() throttle.
+ */
+unsigned long zfs_arc_dirty_limit_percent = 50; /* total dirty data limit */
+unsigned long zfs_arc_anon_limit_percent = 25; /* anon block dirty limit */
+unsigned long zfs_arc_pool_dirty_percent = 20; /* each pool's anon allowance */
+
+/*
+ * Enable or disable compressed arc buffers.
+ */
+int zfs_compressed_arc_enabled = B_TRUE;
+
+/*
+ * ARC will evict meta buffers that exceed arc_meta_limit. This
+ * tunable make arc_meta_limit adjustable for different workloads.
+ */
+unsigned long zfs_arc_meta_limit_percent = 75;
+
+/*
+ * Percentage that can be consumed by dnodes of ARC meta buffers.
+ */
+unsigned long zfs_arc_dnode_limit_percent = 10;
+
+/*
+ * These tunables are Linux specific
+ */
+unsigned long zfs_arc_sys_free = 0;
+int zfs_arc_min_prefetch_ms = 0;
+int zfs_arc_min_prescient_prefetch_ms = 0;
+int zfs_arc_p_dampener_disable = 1;
+int zfs_arc_meta_prune = 10000;
+int zfs_arc_meta_strategy = ARC_STRATEGY_META_BALANCED;
+int zfs_arc_meta_adjust_restarts = 4096;
+int zfs_arc_lotsfree_percent = 10;
+
+/* The 6 states: */
+arc_state_t ARC_anon;
+arc_state_t ARC_mru;
+arc_state_t ARC_mru_ghost;
+arc_state_t ARC_mfu;
+arc_state_t ARC_mfu_ghost;
+arc_state_t ARC_l2c_only;
+
+arc_stats_t arc_stats = {
+ { "hits", KSTAT_DATA_UINT64 },
+ { "misses", KSTAT_DATA_UINT64 },
+ { "demand_data_hits", KSTAT_DATA_UINT64 },
+ { "demand_data_misses", KSTAT_DATA_UINT64 },
+ { "demand_metadata_hits", KSTAT_DATA_UINT64 },
+ { "demand_metadata_misses", KSTAT_DATA_UINT64 },
+ { "prefetch_data_hits", KSTAT_DATA_UINT64 },
+ { "prefetch_data_misses", KSTAT_DATA_UINT64 },
+ { "prefetch_metadata_hits", KSTAT_DATA_UINT64 },
+ { "prefetch_metadata_misses", KSTAT_DATA_UINT64 },
+ { "mru_hits", KSTAT_DATA_UINT64 },
+ { "mru_ghost_hits", KSTAT_DATA_UINT64 },
+ { "mfu_hits", KSTAT_DATA_UINT64 },
+ { "mfu_ghost_hits", KSTAT_DATA_UINT64 },
+ { "deleted", KSTAT_DATA_UINT64 },
+ { "mutex_miss", KSTAT_DATA_UINT64 },
+ { "access_skip", KSTAT_DATA_UINT64 },
+ { "evict_skip", KSTAT_DATA_UINT64 },
+ { "evict_not_enough", KSTAT_DATA_UINT64 },
+ { "evict_l2_cached", KSTAT_DATA_UINT64 },
+ { "evict_l2_eligible", KSTAT_DATA_UINT64 },
+ { "evict_l2_ineligible", KSTAT_DATA_UINT64 },
+ { "evict_l2_skip", KSTAT_DATA_UINT64 },
+ { "hash_elements", KSTAT_DATA_UINT64 },
+ { "hash_elements_max", KSTAT_DATA_UINT64 },
+ { "hash_collisions", KSTAT_DATA_UINT64 },
+ { "hash_chains", KSTAT_DATA_UINT64 },
+ { "hash_chain_max", KSTAT_DATA_UINT64 },
+ { "p", KSTAT_DATA_UINT64 },
+ { "c", KSTAT_DATA_UINT64 },
+ { "c_min", KSTAT_DATA_UINT64 },
+ { "c_max", KSTAT_DATA_UINT64 },
+ { "size", KSTAT_DATA_UINT64 },
+ { "compressed_size", KSTAT_DATA_UINT64 },
+ { "uncompressed_size", KSTAT_DATA_UINT64 },
+ { "overhead_size", KSTAT_DATA_UINT64 },
+ { "hdr_size", KSTAT_DATA_UINT64 },
+ { "data_size", KSTAT_DATA_UINT64 },
+ { "metadata_size", KSTAT_DATA_UINT64 },
+ { "dbuf_size", KSTAT_DATA_UINT64 },
+ { "dnode_size", KSTAT_DATA_UINT64 },
+ { "bonus_size", KSTAT_DATA_UINT64 },
+#if defined(COMPAT_FREEBSD11)
+ { "other_size", KSTAT_DATA_UINT64 },
+#endif
+ { "anon_size", KSTAT_DATA_UINT64 },
+ { "anon_evictable_data", KSTAT_DATA_UINT64 },
+ { "anon_evictable_metadata", KSTAT_DATA_UINT64 },
+ { "mru_size", KSTAT_DATA_UINT64 },
+ { "mru_evictable_data", KSTAT_DATA_UINT64 },
+ { "mru_evictable_metadata", KSTAT_DATA_UINT64 },
+ { "mru_ghost_size", KSTAT_DATA_UINT64 },
+ { "mru_ghost_evictable_data", KSTAT_DATA_UINT64 },
+ { "mru_ghost_evictable_metadata", KSTAT_DATA_UINT64 },
+ { "mfu_size", KSTAT_DATA_UINT64 },
+ { "mfu_evictable_data", KSTAT_DATA_UINT64 },
+ { "mfu_evictable_metadata", KSTAT_DATA_UINT64 },
+ { "mfu_ghost_size", KSTAT_DATA_UINT64 },
+ { "mfu_ghost_evictable_data", KSTAT_DATA_UINT64 },
+ { "mfu_ghost_evictable_metadata", KSTAT_DATA_UINT64 },
+ { "l2_hits", KSTAT_DATA_UINT64 },
+ { "l2_misses", KSTAT_DATA_UINT64 },
+ { "l2_feeds", KSTAT_DATA_UINT64 },
+ { "l2_rw_clash", KSTAT_DATA_UINT64 },
+ { "l2_read_bytes", KSTAT_DATA_UINT64 },
+ { "l2_write_bytes", KSTAT_DATA_UINT64 },
+ { "l2_writes_sent", KSTAT_DATA_UINT64 },
+ { "l2_writes_done", KSTAT_DATA_UINT64 },
+ { "l2_writes_error", KSTAT_DATA_UINT64 },
+ { "l2_writes_lock_retry", KSTAT_DATA_UINT64 },
+ { "l2_evict_lock_retry", KSTAT_DATA_UINT64 },
+ { "l2_evict_reading", KSTAT_DATA_UINT64 },
+ { "l2_evict_l1cached", KSTAT_DATA_UINT64 },
+ { "l2_free_on_write", KSTAT_DATA_UINT64 },
+ { "l2_abort_lowmem", KSTAT_DATA_UINT64 },
+ { "l2_cksum_bad", KSTAT_DATA_UINT64 },
+ { "l2_io_error", KSTAT_DATA_UINT64 },
+ { "l2_size", KSTAT_DATA_UINT64 },
+ { "l2_asize", KSTAT_DATA_UINT64 },
+ { "l2_hdr_size", KSTAT_DATA_UINT64 },
+ { "l2_log_blk_writes", KSTAT_DATA_UINT64 },
+ { "l2_log_blk_avg_asize", KSTAT_DATA_UINT64 },
+ { "l2_log_blk_asize", KSTAT_DATA_UINT64 },
+ { "l2_log_blk_count", KSTAT_DATA_UINT64 },
+ { "l2_data_to_meta_ratio", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_success", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_unsupported", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_io_errors", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_dh_errors", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_cksum_lb_errors", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_lowmem", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_size", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_asize", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_bufs", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_bufs_precached", KSTAT_DATA_UINT64 },
+ { "l2_rebuild_log_blks", KSTAT_DATA_UINT64 },
+ { "memory_throttle_count", KSTAT_DATA_UINT64 },
+ { "memory_direct_count", KSTAT_DATA_UINT64 },
+ { "memory_indirect_count", KSTAT_DATA_UINT64 },
+ { "memory_all_bytes", KSTAT_DATA_UINT64 },
+ { "memory_free_bytes", KSTAT_DATA_UINT64 },
+ { "memory_available_bytes", KSTAT_DATA_INT64 },
+ { "arc_no_grow", KSTAT_DATA_UINT64 },
+ { "arc_tempreserve", KSTAT_DATA_UINT64 },
+ { "arc_loaned_bytes", KSTAT_DATA_UINT64 },
+ { "arc_prune", KSTAT_DATA_UINT64 },
+ { "arc_meta_used", KSTAT_DATA_UINT64 },
+ { "arc_meta_limit", KSTAT_DATA_UINT64 },
+ { "arc_dnode_limit", KSTAT_DATA_UINT64 },
+ { "arc_meta_max", KSTAT_DATA_UINT64 },
+ { "arc_meta_min", KSTAT_DATA_UINT64 },
+ { "async_upgrade_sync", KSTAT_DATA_UINT64 },
+ { "demand_hit_predictive_prefetch", KSTAT_DATA_UINT64 },
+ { "demand_hit_prescient_prefetch", KSTAT_DATA_UINT64 },
+ { "arc_need_free", KSTAT_DATA_UINT64 },
+ { "arc_sys_free", KSTAT_DATA_UINT64 },
+ { "arc_raw_size", KSTAT_DATA_UINT64 },
+ { "cached_only_in_progress", KSTAT_DATA_UINT64 },
+ { "abd_chunk_waste_size", KSTAT_DATA_UINT64 },
+};
+
+#define ARCSTAT_MAX(stat, val) { \
+ uint64_t m; \
+ while ((val) > (m = arc_stats.stat.value.ui64) && \
+ (m != atomic_cas_64(&arc_stats.stat.value.ui64, m, (val)))) \
+ continue; \
+}
+
+#define ARCSTAT_MAXSTAT(stat) \
+ ARCSTAT_MAX(stat##_max, arc_stats.stat.value.ui64)
+
+/*
+ * We define a macro to allow ARC hits/misses to be easily broken down by
+ * two separate conditions, giving a total of four different subtypes for
+ * each of hits and misses (so eight statistics total).
+ */
+#define ARCSTAT_CONDSTAT(cond1, stat1, notstat1, cond2, stat2, notstat2, stat) \
+ if (cond1) { \
+ if (cond2) { \
+ ARCSTAT_BUMP(arcstat_##stat1##_##stat2##_##stat); \
+ } else { \
+ ARCSTAT_BUMP(arcstat_##stat1##_##notstat2##_##stat); \
+ } \
+ } else { \
+ if (cond2) { \
+ ARCSTAT_BUMP(arcstat_##notstat1##_##stat2##_##stat); \
+ } else { \
+ ARCSTAT_BUMP(arcstat_##notstat1##_##notstat2##_##stat);\
+ } \
+ }
+
+/*
+ * This macro allows us to use kstats as floating averages. Each time we
+ * update this kstat, we first factor it and the update value by
+ * ARCSTAT_AVG_FACTOR to shrink the new value's contribution to the overall
+ * average. This macro assumes that integer loads and stores are atomic, but
+ * is not safe for multiple writers updating the kstat in parallel (only the
+ * last writer's update will remain).
+ */
+#define ARCSTAT_F_AVG_FACTOR 3
+#define ARCSTAT_F_AVG(stat, value) \
+ do { \
+ uint64_t x = ARCSTAT(stat); \
+ x = x - x / ARCSTAT_F_AVG_FACTOR + \
+ (value) / ARCSTAT_F_AVG_FACTOR; \
+ ARCSTAT(stat) = x; \
+ _NOTE(CONSTCOND) \
+ } while (0)
+
+kstat_t *arc_ksp;
+static arc_state_t *arc_anon;
+static arc_state_t *arc_mru_ghost;
+static arc_state_t *arc_mfu_ghost;
+static arc_state_t *arc_l2c_only;
+
+arc_state_t *arc_mru;
+arc_state_t *arc_mfu;
+
+/*
+ * There are several ARC variables that are critical to export as kstats --
+ * but we don't want to have to grovel around in the kstat whenever we wish to
+ * manipulate them. For these variables, we therefore define them to be in
+ * terms of the statistic variable. This assures that we are not introducing
+ * the possibility of inconsistency by having shadow copies of the variables,
+ * while still allowing the code to be readable.
+ */
+#define arc_tempreserve ARCSTAT(arcstat_tempreserve)
+#define arc_loaned_bytes ARCSTAT(arcstat_loaned_bytes)
+#define arc_meta_limit ARCSTAT(arcstat_meta_limit) /* max size for metadata */
+/* max size for dnodes */
+#define arc_dnode_size_limit ARCSTAT(arcstat_dnode_limit)
+#define arc_meta_min ARCSTAT(arcstat_meta_min) /* min size for metadata */
+#define arc_meta_max ARCSTAT(arcstat_meta_max) /* max size of metadata */
+#define arc_need_free ARCSTAT(arcstat_need_free) /* waiting to be evicted */
+
+/* size of all b_rabd's in entire arc */
+#define arc_raw_size ARCSTAT(arcstat_raw_size)
+/* compressed size of entire arc */
+#define arc_compressed_size ARCSTAT(arcstat_compressed_size)
+/* uncompressed size of entire arc */
+#define arc_uncompressed_size ARCSTAT(arcstat_uncompressed_size)
+/* number of bytes in the arc from arc_buf_t's */
+#define arc_overhead_size ARCSTAT(arcstat_overhead_size)
+
+/*
+ * There are also some ARC variables that we want to export, but that are
+ * updated so often that having the canonical representation be the statistic
+ * variable causes a performance bottleneck. We want to use aggsum_t's for these
+ * instead, but still be able to export the kstat in the same way as before.
+ * The solution is to always use the aggsum version, except in the kstat update
+ * callback.
+ */
+aggsum_t arc_size;
+aggsum_t arc_meta_used;
+aggsum_t astat_data_size;
+aggsum_t astat_metadata_size;
+aggsum_t astat_dbuf_size;
+aggsum_t astat_dnode_size;
+aggsum_t astat_bonus_size;
+aggsum_t astat_hdr_size;
+aggsum_t astat_l2_hdr_size;
+aggsum_t astat_abd_chunk_waste_size;
+
+hrtime_t arc_growtime;
+list_t arc_prune_list;
+kmutex_t arc_prune_mtx;
+taskq_t *arc_prune_taskq;
+
+#define GHOST_STATE(state) \
+ ((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \
+ (state) == arc_l2c_only)
+
+#define HDR_IN_HASH_TABLE(hdr) ((hdr)->b_flags & ARC_FLAG_IN_HASH_TABLE)
+#define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS)
+#define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_FLAG_IO_ERROR)
+#define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_FLAG_PREFETCH)
+#define HDR_PRESCIENT_PREFETCH(hdr) \
+ ((hdr)->b_flags & ARC_FLAG_PRESCIENT_PREFETCH)
+#define HDR_COMPRESSION_ENABLED(hdr) \
+ ((hdr)->b_flags & ARC_FLAG_COMPRESSED_ARC)
+
+#define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_FLAG_L2CACHE)
+#define HDR_L2_READING(hdr) \
+ (((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS) && \
+ ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR))
+#define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_FLAG_L2_WRITING)
+#define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_FLAG_L2_EVICTED)
+#define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_FLAG_L2_WRITE_HEAD)
+#define HDR_PROTECTED(hdr) ((hdr)->b_flags & ARC_FLAG_PROTECTED)
+#define HDR_NOAUTH(hdr) ((hdr)->b_flags & ARC_FLAG_NOAUTH)
+#define HDR_SHARED_DATA(hdr) ((hdr)->b_flags & ARC_FLAG_SHARED_DATA)
+
+#define HDR_ISTYPE_METADATA(hdr) \
+ ((hdr)->b_flags & ARC_FLAG_BUFC_METADATA)
+#define HDR_ISTYPE_DATA(hdr) (!HDR_ISTYPE_METADATA(hdr))
+
+#define HDR_HAS_L1HDR(hdr) ((hdr)->b_flags & ARC_FLAG_HAS_L1HDR)
+#define HDR_HAS_L2HDR(hdr) ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR)
+#define HDR_HAS_RABD(hdr) \
+ (HDR_HAS_L1HDR(hdr) && HDR_PROTECTED(hdr) && \
+ (hdr)->b_crypt_hdr.b_rabd != NULL)
+#define HDR_ENCRYPTED(hdr) \
+ (HDR_PROTECTED(hdr) && DMU_OT_IS_ENCRYPTED((hdr)->b_crypt_hdr.b_ot))
+#define HDR_AUTHENTICATED(hdr) \
+ (HDR_PROTECTED(hdr) && !DMU_OT_IS_ENCRYPTED((hdr)->b_crypt_hdr.b_ot))
+
+/* For storing compression mode in b_flags */
+#define HDR_COMPRESS_OFFSET (highbit64(ARC_FLAG_COMPRESS_0) - 1)
+
+#define HDR_GET_COMPRESS(hdr) ((enum zio_compress)BF32_GET((hdr)->b_flags, \
+ HDR_COMPRESS_OFFSET, SPA_COMPRESSBITS))
+#define HDR_SET_COMPRESS(hdr, cmp) BF32_SET((hdr)->b_flags, \
+ HDR_COMPRESS_OFFSET, SPA_COMPRESSBITS, (cmp));
+
+#define ARC_BUF_LAST(buf) ((buf)->b_next == NULL)
+#define ARC_BUF_SHARED(buf) ((buf)->b_flags & ARC_BUF_FLAG_SHARED)
+#define ARC_BUF_COMPRESSED(buf) ((buf)->b_flags & ARC_BUF_FLAG_COMPRESSED)
+#define ARC_BUF_ENCRYPTED(buf) ((buf)->b_flags & ARC_BUF_FLAG_ENCRYPTED)
+
+/*
+ * Other sizes
+ */
+
+#define HDR_FULL_CRYPT_SIZE ((int64_t)sizeof (arc_buf_hdr_t))
+#define HDR_FULL_SIZE ((int64_t)offsetof(arc_buf_hdr_t, b_crypt_hdr))
+#define HDR_L2ONLY_SIZE ((int64_t)offsetof(arc_buf_hdr_t, b_l1hdr))
+
+/*
+ * Hash table routines
+ */
+
+#define HT_LOCK_ALIGN 64
+#define HT_LOCK_PAD (P2NPHASE(sizeof (kmutex_t), (HT_LOCK_ALIGN)))
+
+struct ht_lock {
+ kmutex_t ht_lock;
+#ifdef _KERNEL
+ unsigned char pad[HT_LOCK_PAD];
+#endif
+};
+
+#define BUF_LOCKS 8192
+typedef struct buf_hash_table {
+ uint64_t ht_mask;
+ arc_buf_hdr_t **ht_table;
+ struct ht_lock ht_locks[BUF_LOCKS];
+} buf_hash_table_t;
+
+static buf_hash_table_t buf_hash_table;
+
+#define BUF_HASH_INDEX(spa, dva, birth) \
+ (buf_hash(spa, dva, birth) & buf_hash_table.ht_mask)
+#define BUF_HASH_LOCK_NTRY(idx) (buf_hash_table.ht_locks[idx & (BUF_LOCKS-1)])
+#define BUF_HASH_LOCK(idx) (&(BUF_HASH_LOCK_NTRY(idx).ht_lock))
+#define HDR_LOCK(hdr) \
+ (BUF_HASH_LOCK(BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth)))
+
+uint64_t zfs_crc64_table[256];
+
+/*
+ * Level 2 ARC
+ */
+
+#define L2ARC_WRITE_SIZE (8 * 1024 * 1024) /* initial write max */
+#define L2ARC_HEADROOM 2 /* num of writes */
+
+/*
+ * If we discover during ARC scan any buffers to be compressed, we boost
+ * our headroom for the next scanning cycle by this percentage multiple.
+ */
+#define L2ARC_HEADROOM_BOOST 200
+#define L2ARC_FEED_SECS 1 /* caching interval secs */
+#define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */
+
+/*
+ * We can feed L2ARC from two states of ARC buffers, mru and mfu,
+ * and each of the state has two types: data and metadata.
+ */
+#define L2ARC_FEED_TYPES 4
+
+#define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent)
+#define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done)
+
+/* L2ARC Performance Tunables */
+unsigned long l2arc_write_max = L2ARC_WRITE_SIZE; /* def max write size */
+unsigned long l2arc_write_boost = L2ARC_WRITE_SIZE; /* extra warmup write */
+unsigned long l2arc_headroom = L2ARC_HEADROOM; /* # of dev writes */
+unsigned long l2arc_headroom_boost = L2ARC_HEADROOM_BOOST;
+unsigned long l2arc_feed_secs = L2ARC_FEED_SECS; /* interval seconds */
+unsigned long l2arc_feed_min_ms = L2ARC_FEED_MIN_MS; /* min interval msecs */
+int l2arc_noprefetch = B_TRUE; /* don't cache prefetch bufs */
+int l2arc_feed_again = B_TRUE; /* turbo warmup */
+int l2arc_norw = B_FALSE; /* no reads during writes */
+int l2arc_meta_percent = 33; /* limit on headers size */
+
+/*
+ * L2ARC Internals
+ */
+static list_t L2ARC_dev_list; /* device list */
+static list_t *l2arc_dev_list; /* device list pointer */
+static kmutex_t l2arc_dev_mtx; /* device list mutex */
+static l2arc_dev_t *l2arc_dev_last; /* last device used */
+static list_t L2ARC_free_on_write; /* free after write buf list */
+static list_t *l2arc_free_on_write; /* free after write list ptr */
+static kmutex_t l2arc_free_on_write_mtx; /* mutex for list */
+static uint64_t l2arc_ndev; /* number of devices */
+
+typedef struct l2arc_read_callback {
+ arc_buf_hdr_t *l2rcb_hdr; /* read header */
+ blkptr_t l2rcb_bp; /* original blkptr */
+ zbookmark_phys_t l2rcb_zb; /* original bookmark */
+ int l2rcb_flags; /* original flags */
+ abd_t *l2rcb_abd; /* temporary buffer */
+} l2arc_read_callback_t;
+
+typedef struct l2arc_data_free {
+ /* protected by l2arc_free_on_write_mtx */
+ abd_t *l2df_abd;
+ size_t l2df_size;
+ arc_buf_contents_t l2df_type;
+ list_node_t l2df_list_node;
+} l2arc_data_free_t;
+
+typedef enum arc_fill_flags {
+ ARC_FILL_LOCKED = 1 << 0, /* hdr lock is held */
+ ARC_FILL_COMPRESSED = 1 << 1, /* fill with compressed data */
+ ARC_FILL_ENCRYPTED = 1 << 2, /* fill with encrypted data */
+ ARC_FILL_NOAUTH = 1 << 3, /* don't attempt to authenticate */
+ ARC_FILL_IN_PLACE = 1 << 4 /* fill in place (special case) */
+} arc_fill_flags_t;
+
+static kmutex_t l2arc_feed_thr_lock;
+static kcondvar_t l2arc_feed_thr_cv;
+static uint8_t l2arc_thread_exit;
+
+static kmutex_t l2arc_rebuild_thr_lock;
+static kcondvar_t l2arc_rebuild_thr_cv;
+
+enum arc_hdr_alloc_flags {
+ ARC_HDR_ALLOC_RDATA = 0x1,
+ ARC_HDR_DO_ADAPT = 0x2,
+};
+
+
+static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, void *, boolean_t);
+static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, void *);
+static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, void *, boolean_t);
+static void arc_free_data_abd(arc_buf_hdr_t *, abd_t *, uint64_t, void *);
+static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, void *);
+static void arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag);
+static void arc_hdr_free_abd(arc_buf_hdr_t *, boolean_t);
+static void arc_hdr_alloc_abd(arc_buf_hdr_t *, int);
+static void arc_access(arc_buf_hdr_t *, kmutex_t *);
+static void arc_buf_watch(arc_buf_t *);
+
+static arc_buf_contents_t arc_buf_type(arc_buf_hdr_t *);
+static uint32_t arc_bufc_to_flags(arc_buf_contents_t);
+static inline void arc_hdr_set_flags(arc_buf_hdr_t *hdr, arc_flags_t flags);
+static inline void arc_hdr_clear_flags(arc_buf_hdr_t *hdr, arc_flags_t flags);
+
+static boolean_t l2arc_write_eligible(uint64_t, arc_buf_hdr_t *);
+static void l2arc_read_done(zio_t *);
+static void l2arc_do_free_on_write(void);
+
+/*
+ * L2ARC TRIM
+ * l2arc_trim_ahead : A ZFS module parameter that controls how much ahead of
+ * the current write size (l2arc_write_max) we should TRIM if we
+ * have filled the device. It is defined as a percentage of the
+ * write size. If set to 100 we trim twice the space required to
+ * accommodate upcoming writes. A minimum of 64MB will be trimmed.
+ * It also enables TRIM of the whole L2ARC device upon creation or
+ * addition to an existing pool or if the header of the device is
+ * invalid upon importing a pool or onlining a cache device. The
+ * default is 0, which disables TRIM on L2ARC altogether as it can
+ * put significant stress on the underlying storage devices. This
+ * will vary depending of how well the specific device handles
+ * these commands.
+ */
+unsigned long l2arc_trim_ahead = 0;
+
+/*
+ * Performance tuning of L2ARC persistence:
+ *
+ * l2arc_rebuild_enabled : A ZFS module parameter that controls whether adding
+ * an L2ARC device (either at pool import or later) will attempt
+ * to rebuild L2ARC buffer contents.
+ * l2arc_rebuild_blocks_min_l2size : A ZFS module parameter that controls
+ * whether log blocks are written to the L2ARC device. If the L2ARC
+ * device is less than 1GB, the amount of data l2arc_evict()
+ * evicts is significant compared to the amount of restored L2ARC
+ * data. In this case do not write log blocks in L2ARC in order
+ * not to waste space.
+ */
+int l2arc_rebuild_enabled = B_TRUE;
+unsigned long l2arc_rebuild_blocks_min_l2size = 1024 * 1024 * 1024;
+
+/* L2ARC persistence rebuild control routines. */
+void l2arc_rebuild_vdev(vdev_t *vd, boolean_t reopen);
+static void l2arc_dev_rebuild_thread(void *arg);
+static int l2arc_rebuild(l2arc_dev_t *dev);
+
+/* L2ARC persistence read I/O routines. */
+static int l2arc_dev_hdr_read(l2arc_dev_t *dev);
+static int l2arc_log_blk_read(l2arc_dev_t *dev,
+ const l2arc_log_blkptr_t *this_lp, const l2arc_log_blkptr_t *next_lp,
+ l2arc_log_blk_phys_t *this_lb, l2arc_log_blk_phys_t *next_lb,
+ zio_t *this_io, zio_t **next_io);
+static zio_t *l2arc_log_blk_fetch(vdev_t *vd,
+ const l2arc_log_blkptr_t *lp, l2arc_log_blk_phys_t *lb);
+static void l2arc_log_blk_fetch_abort(zio_t *zio);
+
+/* L2ARC persistence block restoration routines. */
+static void l2arc_log_blk_restore(l2arc_dev_t *dev,
+ const l2arc_log_blk_phys_t *lb, uint64_t lb_asize, uint64_t lb_daddr);
+static void l2arc_hdr_restore(const l2arc_log_ent_phys_t *le,
+ l2arc_dev_t *dev);
+
+/* L2ARC persistence write I/O routines. */
+static void l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio,
+ l2arc_write_callback_t *cb);
+
+/* L2ARC persistence auxiliary routines. */
+boolean_t l2arc_log_blkptr_valid(l2arc_dev_t *dev,
+ const l2arc_log_blkptr_t *lbp);
+static boolean_t l2arc_log_blk_insert(l2arc_dev_t *dev,
+ const arc_buf_hdr_t *ab);
+boolean_t l2arc_range_check_overlap(uint64_t bottom,
+ uint64_t top, uint64_t check);
+static void l2arc_blk_fetch_done(zio_t *zio);
+static inline uint64_t
+ l2arc_log_blk_overhead(uint64_t write_sz, l2arc_dev_t *dev);
+
+/*
+ * We use Cityhash for this. It's fast, and has good hash properties without
+ * requiring any large static buffers.
+ */
+static uint64_t
+buf_hash(uint64_t spa, const dva_t *dva, uint64_t birth)
+{
+ return (cityhash4(spa, dva->dva_word[0], dva->dva_word[1], birth));
+}
+
+#define HDR_EMPTY(hdr) \
+ ((hdr)->b_dva.dva_word[0] == 0 && \
+ (hdr)->b_dva.dva_word[1] == 0)
+
+#define HDR_EMPTY_OR_LOCKED(hdr) \
+ (HDR_EMPTY(hdr) || MUTEX_HELD(HDR_LOCK(hdr)))
+
+#define HDR_EQUAL(spa, dva, birth, hdr) \
+ ((hdr)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \
+ ((hdr)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \
+ ((hdr)->b_birth == birth) && ((hdr)->b_spa == spa)
+
+static void
+buf_discard_identity(arc_buf_hdr_t *hdr)
+{
+ hdr->b_dva.dva_word[0] = 0;
+ hdr->b_dva.dva_word[1] = 0;
+ hdr->b_birth = 0;
+}
+
+static arc_buf_hdr_t *
+buf_hash_find(uint64_t spa, const blkptr_t *bp, kmutex_t **lockp)
+{
+ const dva_t *dva = BP_IDENTITY(bp);
+ uint64_t birth = BP_PHYSICAL_BIRTH(bp);
+ uint64_t idx = BUF_HASH_INDEX(spa, dva, birth);
+ kmutex_t *hash_lock = BUF_HASH_LOCK(idx);
+ arc_buf_hdr_t *hdr;
+
+ mutex_enter(hash_lock);
+ for (hdr = buf_hash_table.ht_table[idx]; hdr != NULL;
+ hdr = hdr->b_hash_next) {
+ if (HDR_EQUAL(spa, dva, birth, hdr)) {
+ *lockp = hash_lock;
+ return (hdr);
+ }
+ }
+ mutex_exit(hash_lock);
+ *lockp = NULL;
+ return (NULL);
+}
+
+/*
+ * Insert an entry into the hash table. If there is already an element
+ * equal to elem in the hash table, then the already existing element
+ * will be returned and the new element will not be inserted.
+ * Otherwise returns NULL.
+ * If lockp == NULL, the caller is assumed to already hold the hash lock.
+ */
+static arc_buf_hdr_t *
+buf_hash_insert(arc_buf_hdr_t *hdr, kmutex_t **lockp)
+{
+ uint64_t idx = BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth);
+ kmutex_t *hash_lock = BUF_HASH_LOCK(idx);
+ arc_buf_hdr_t *fhdr;
+ uint32_t i;
+
+ ASSERT(!DVA_IS_EMPTY(&hdr->b_dva));
+ ASSERT(hdr->b_birth != 0);
+ ASSERT(!HDR_IN_HASH_TABLE(hdr));
+
+ if (lockp != NULL) {
+ *lockp = hash_lock;
+ mutex_enter(hash_lock);
+ } else {
+ ASSERT(MUTEX_HELD(hash_lock));
+ }
+
+ for (fhdr = buf_hash_table.ht_table[idx], i = 0; fhdr != NULL;
+ fhdr = fhdr->b_hash_next, i++) {
+ if (HDR_EQUAL(hdr->b_spa, &hdr->b_dva, hdr->b_birth, fhdr))
+ return (fhdr);
+ }
+
+ hdr->b_hash_next = buf_hash_table.ht_table[idx];
+ buf_hash_table.ht_table[idx] = hdr;
+ arc_hdr_set_flags(hdr, ARC_FLAG_IN_HASH_TABLE);
+
+ /* collect some hash table performance data */
+ if (i > 0) {
+ ARCSTAT_BUMP(arcstat_hash_collisions);
+ if (i == 1)
+ ARCSTAT_BUMP(arcstat_hash_chains);
+
+ ARCSTAT_MAX(arcstat_hash_chain_max, i);
+ }
+
+ ARCSTAT_BUMP(arcstat_hash_elements);
+ ARCSTAT_MAXSTAT(arcstat_hash_elements);
+
+ return (NULL);
+}
+
+static void
+buf_hash_remove(arc_buf_hdr_t *hdr)
+{
+ arc_buf_hdr_t *fhdr, **hdrp;
+ uint64_t idx = BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth);
+
+ ASSERT(MUTEX_HELD(BUF_HASH_LOCK(idx)));
+ ASSERT(HDR_IN_HASH_TABLE(hdr));
+
+ hdrp = &buf_hash_table.ht_table[idx];
+ while ((fhdr = *hdrp) != hdr) {
+ ASSERT3P(fhdr, !=, NULL);
+ hdrp = &fhdr->b_hash_next;
+ }
+ *hdrp = hdr->b_hash_next;
+ hdr->b_hash_next = NULL;
+ arc_hdr_clear_flags(hdr, ARC_FLAG_IN_HASH_TABLE);
+
+ /* collect some hash table performance data */
+ ARCSTAT_BUMPDOWN(arcstat_hash_elements);
+
+ if (buf_hash_table.ht_table[idx] &&
+ buf_hash_table.ht_table[idx]->b_hash_next == NULL)
+ ARCSTAT_BUMPDOWN(arcstat_hash_chains);
+}
+
+/*
+ * Global data structures and functions for the buf kmem cache.
+ */
+
+static kmem_cache_t *hdr_full_cache;
+static kmem_cache_t *hdr_full_crypt_cache;
+static kmem_cache_t *hdr_l2only_cache;
+static kmem_cache_t *buf_cache;
+
+static void
+buf_fini(void)
+{
+ int i;
+
+#if defined(_KERNEL)
+ /*
+ * Large allocations which do not require contiguous pages
+ * should be using vmem_free() in the linux kernel\
+ */
+ vmem_free(buf_hash_table.ht_table,
+ (buf_hash_table.ht_mask + 1) * sizeof (void *));
+#else
+ kmem_free(buf_hash_table.ht_table,
+ (buf_hash_table.ht_mask + 1) * sizeof (void *));
+#endif
+ for (i = 0; i < BUF_LOCKS; i++)
+ mutex_destroy(&buf_hash_table.ht_locks[i].ht_lock);
+ kmem_cache_destroy(hdr_full_cache);
+ kmem_cache_destroy(hdr_full_crypt_cache);
+ kmem_cache_destroy(hdr_l2only_cache);
+ kmem_cache_destroy(buf_cache);
+}
+
+/*
+ * Constructor callback - called when the cache is empty
+ * and a new buf is requested.
+ */
+/* ARGSUSED */
+static int
+hdr_full_cons(void *vbuf, void *unused, int kmflag)
+{
+ arc_buf_hdr_t *hdr = vbuf;
+
+ bzero(hdr, HDR_FULL_SIZE);
+ hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
+ cv_init(&hdr->b_l1hdr.b_cv, NULL, CV_DEFAULT, NULL);
+ zfs_refcount_create(&hdr->b_l1hdr.b_refcnt);
+ mutex_init(&hdr->b_l1hdr.b_freeze_lock, NULL, MUTEX_DEFAULT, NULL);
+ list_link_init(&hdr->b_l1hdr.b_arc_node);
+ list_link_init(&hdr->b_l2hdr.b_l2node);
+ multilist_link_init(&hdr->b_l1hdr.b_arc_node);
+ arc_space_consume(HDR_FULL_SIZE, ARC_SPACE_HDRS);
+
+ return (0);
+}
+
+/* ARGSUSED */
+static int
+hdr_full_crypt_cons(void *vbuf, void *unused, int kmflag)
+{
+ arc_buf_hdr_t *hdr = vbuf;
+
+ hdr_full_cons(vbuf, unused, kmflag);
+ bzero(&hdr->b_crypt_hdr, sizeof (hdr->b_crypt_hdr));
+ arc_space_consume(sizeof (hdr->b_crypt_hdr), ARC_SPACE_HDRS);
+
+ return (0);
+}
+
+/* ARGSUSED */
+static int
+hdr_l2only_cons(void *vbuf, void *unused, int kmflag)
+{
+ arc_buf_hdr_t *hdr = vbuf;
+
+ bzero(hdr, HDR_L2ONLY_SIZE);
+ arc_space_consume(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS);
+
+ return (0);
+}
+
+/* ARGSUSED */
+static int
+buf_cons(void *vbuf, void *unused, int kmflag)
+{
+ arc_buf_t *buf = vbuf;
+
+ bzero(buf, sizeof (arc_buf_t));
+ mutex_init(&buf->b_evict_lock, NULL, MUTEX_DEFAULT, NULL);
+ arc_space_consume(sizeof (arc_buf_t), ARC_SPACE_HDRS);
+
+ return (0);
+}
+
+/*
+ * Destructor callback - called when a cached buf is
+ * no longer required.
+ */
+/* ARGSUSED */
+static void
+hdr_full_dest(void *vbuf, void *unused)
+{
+ arc_buf_hdr_t *hdr = vbuf;
+
+ ASSERT(HDR_EMPTY(hdr));
+ cv_destroy(&hdr->b_l1hdr.b_cv);
+ zfs_refcount_destroy(&hdr->b_l1hdr.b_refcnt);
+ mutex_destroy(&hdr->b_l1hdr.b_freeze_lock);
+ ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
+ arc_space_return(HDR_FULL_SIZE, ARC_SPACE_HDRS);
+}
+
+/* ARGSUSED */
+static void
+hdr_full_crypt_dest(void *vbuf, void *unused)
+{
+ arc_buf_hdr_t *hdr = vbuf;
+
+ hdr_full_dest(vbuf, unused);
+ arc_space_return(sizeof (hdr->b_crypt_hdr), ARC_SPACE_HDRS);
+}
+
+/* ARGSUSED */
+static void
+hdr_l2only_dest(void *vbuf, void *unused)
+{
+ arc_buf_hdr_t *hdr __maybe_unused = vbuf;
+
+ ASSERT(HDR_EMPTY(hdr));
+ arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS);
+}
+
+/* ARGSUSED */
+static void
+buf_dest(void *vbuf, void *unused)
+{
+ arc_buf_t *buf = vbuf;
+
+ mutex_destroy(&buf->b_evict_lock);
+ arc_space_return(sizeof (arc_buf_t), ARC_SPACE_HDRS);
+}
+
+static void
+buf_init(void)
+{
+ uint64_t *ct = NULL;
+ uint64_t hsize = 1ULL << 12;
+ int i, j;
+
+ /*
+ * The hash table is big enough to fill all of physical memory
+ * with an average block size of zfs_arc_average_blocksize (default 8K).
+ * By default, the table will take up
+ * totalmem * sizeof(void*) / 8K (1MB per GB with 8-byte pointers).
+ */
+ while (hsize * zfs_arc_average_blocksize < arc_all_memory())
+ hsize <<= 1;
+retry:
+ buf_hash_table.ht_mask = hsize - 1;
+#if defined(_KERNEL)
+ /*
+ * Large allocations which do not require contiguous pages
+ * should be using vmem_alloc() in the linux kernel
+ */
+ buf_hash_table.ht_table =
+ vmem_zalloc(hsize * sizeof (void*), KM_SLEEP);
+#else
+ buf_hash_table.ht_table =
+ kmem_zalloc(hsize * sizeof (void*), KM_NOSLEEP);
+#endif
+ if (buf_hash_table.ht_table == NULL) {
+ ASSERT(hsize > (1ULL << 8));
+ hsize >>= 1;
+ goto retry;
+ }
+
+ hdr_full_cache = kmem_cache_create("arc_buf_hdr_t_full", HDR_FULL_SIZE,
+ 0, hdr_full_cons, hdr_full_dest, NULL, NULL, NULL, 0);
+ hdr_full_crypt_cache = kmem_cache_create("arc_buf_hdr_t_full_crypt",
+ HDR_FULL_CRYPT_SIZE, 0, hdr_full_crypt_cons, hdr_full_crypt_dest,
+ NULL, NULL, NULL, 0);
+ hdr_l2only_cache = kmem_cache_create("arc_buf_hdr_t_l2only",
+ HDR_L2ONLY_SIZE, 0, hdr_l2only_cons, hdr_l2only_dest, NULL,
+ NULL, NULL, 0);
+ buf_cache = kmem_cache_create("arc_buf_t", sizeof (arc_buf_t),
+ 0, buf_cons, buf_dest, NULL, NULL, NULL, 0);
+
+ for (i = 0; i < 256; i++)
+ for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--)
+ *ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY);
+
+ for (i = 0; i < BUF_LOCKS; i++) {
+ mutex_init(&buf_hash_table.ht_locks[i].ht_lock,
+ NULL, MUTEX_DEFAULT, NULL);
+ }
+}
+
+#define ARC_MINTIME (hz>>4) /* 62 ms */
+
+/*
+ * This is the size that the buf occupies in memory. If the buf is compressed,
+ * it will correspond to the compressed size. You should use this method of
+ * getting the buf size unless you explicitly need the logical size.
+ */
+uint64_t
+arc_buf_size(arc_buf_t *buf)
+{
+ return (ARC_BUF_COMPRESSED(buf) ?
+ HDR_GET_PSIZE(buf->b_hdr) : HDR_GET_LSIZE(buf->b_hdr));
+}
+
+uint64_t
+arc_buf_lsize(arc_buf_t *buf)
+{
+ return (HDR_GET_LSIZE(buf->b_hdr));
+}
+
+/*
+ * This function will return B_TRUE if the buffer is encrypted in memory.
+ * This buffer can be decrypted by calling arc_untransform().
+ */
+boolean_t
+arc_is_encrypted(arc_buf_t *buf)
+{
+ return (ARC_BUF_ENCRYPTED(buf) != 0);
+}
+
+/*
+ * Returns B_TRUE if the buffer represents data that has not had its MAC
+ * verified yet.
+ */
+boolean_t
+arc_is_unauthenticated(arc_buf_t *buf)
+{
+ return (HDR_NOAUTH(buf->b_hdr) != 0);
+}
+
+void
+arc_get_raw_params(arc_buf_t *buf, boolean_t *byteorder, uint8_t *salt,
+ uint8_t *iv, uint8_t *mac)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT(HDR_PROTECTED(hdr));
+
+ bcopy(hdr->b_crypt_hdr.b_salt, salt, ZIO_DATA_SALT_LEN);
+ bcopy(hdr->b_crypt_hdr.b_iv, iv, ZIO_DATA_IV_LEN);
+ bcopy(hdr->b_crypt_hdr.b_mac, mac, ZIO_DATA_MAC_LEN);
+ *byteorder = (hdr->b_l1hdr.b_byteswap == DMU_BSWAP_NUMFUNCS) ?
+ ZFS_HOST_BYTEORDER : !ZFS_HOST_BYTEORDER;
+}
+
+/*
+ * Indicates how this buffer is compressed in memory. If it is not compressed
+ * the value will be ZIO_COMPRESS_OFF. It can be made normally readable with
+ * arc_untransform() as long as it is also unencrypted.
+ */
+enum zio_compress
+arc_get_compression(arc_buf_t *buf)
+{
+ return (ARC_BUF_COMPRESSED(buf) ?
+ HDR_GET_COMPRESS(buf->b_hdr) : ZIO_COMPRESS_OFF);
+}
+
+/*
+ * Return the compression algorithm used to store this data in the ARC. If ARC
+ * compression is enabled or this is an encrypted block, this will be the same
+ * as what's used to store it on-disk. Otherwise, this will be ZIO_COMPRESS_OFF.
+ */
+static inline enum zio_compress
+arc_hdr_get_compress(arc_buf_hdr_t *hdr)
+{
+ return (HDR_COMPRESSION_ENABLED(hdr) ?
+ HDR_GET_COMPRESS(hdr) : ZIO_COMPRESS_OFF);
+}
+
+uint8_t
+arc_get_complevel(arc_buf_t *buf)
+{
+ return (buf->b_hdr->b_complevel);
+}
+
+static inline boolean_t
+arc_buf_is_shared(arc_buf_t *buf)
+{
+ boolean_t shared = (buf->b_data != NULL &&
+ buf->b_hdr->b_l1hdr.b_pabd != NULL &&
+ abd_is_linear(buf->b_hdr->b_l1hdr.b_pabd) &&
+ buf->b_data == abd_to_buf(buf->b_hdr->b_l1hdr.b_pabd));
+ IMPLY(shared, HDR_SHARED_DATA(buf->b_hdr));
+ IMPLY(shared, ARC_BUF_SHARED(buf));
+ IMPLY(shared, ARC_BUF_COMPRESSED(buf) || ARC_BUF_LAST(buf));
+
+ /*
+ * It would be nice to assert arc_can_share() too, but the "hdr isn't
+ * already being shared" requirement prevents us from doing that.
+ */
+
+ return (shared);
+}
+
+/*
+ * Free the checksum associated with this header. If there is no checksum, this
+ * is a no-op.
+ */
+static inline void
+arc_cksum_free(arc_buf_hdr_t *hdr)
+{
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ mutex_enter(&hdr->b_l1hdr.b_freeze_lock);
+ if (hdr->b_l1hdr.b_freeze_cksum != NULL) {
+ kmem_free(hdr->b_l1hdr.b_freeze_cksum, sizeof (zio_cksum_t));
+ hdr->b_l1hdr.b_freeze_cksum = NULL;
+ }
+ mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
+}
+
+/*
+ * Return true iff at least one of the bufs on hdr is not compressed.
+ * Encrypted buffers count as compressed.
+ */
+static boolean_t
+arc_hdr_has_uncompressed_buf(arc_buf_hdr_t *hdr)
+{
+ ASSERT(hdr->b_l1hdr.b_state == arc_anon || HDR_EMPTY_OR_LOCKED(hdr));
+
+ for (arc_buf_t *b = hdr->b_l1hdr.b_buf; b != NULL; b = b->b_next) {
+ if (!ARC_BUF_COMPRESSED(b)) {
+ return (B_TRUE);
+ }
+ }
+ return (B_FALSE);
+}
+
+
+/*
+ * If we've turned on the ZFS_DEBUG_MODIFY flag, verify that the buf's data
+ * matches the checksum that is stored in the hdr. If there is no checksum,
+ * or if the buf is compressed, this is a no-op.
+ */
+static void
+arc_cksum_verify(arc_buf_t *buf)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+ zio_cksum_t zc;
+
+ if (!(zfs_flags & ZFS_DEBUG_MODIFY))
+ return;
+
+ if (ARC_BUF_COMPRESSED(buf))
+ return;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ mutex_enter(&hdr->b_l1hdr.b_freeze_lock);
+
+ if (hdr->b_l1hdr.b_freeze_cksum == NULL || HDR_IO_ERROR(hdr)) {
+ mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
+ return;
+ }
+
+ fletcher_2_native(buf->b_data, arc_buf_size(buf), NULL, &zc);
+ if (!ZIO_CHECKSUM_EQUAL(*hdr->b_l1hdr.b_freeze_cksum, zc))
+ panic("buffer modified while frozen!");
+ mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
+}
+
+/*
+ * This function makes the assumption that data stored in the L2ARC
+ * will be transformed exactly as it is in the main pool. Because of
+ * this we can verify the checksum against the reading process's bp.
+ */
+static boolean_t
+arc_cksum_is_equal(arc_buf_hdr_t *hdr, zio_t *zio)
+{
+ ASSERT(!BP_IS_EMBEDDED(zio->io_bp));
+ VERIFY3U(BP_GET_PSIZE(zio->io_bp), ==, HDR_GET_PSIZE(hdr));
+
+ /*
+ * Block pointers always store the checksum for the logical data.
+ * If the block pointer has the gang bit set, then the checksum
+ * it represents is for the reconstituted data and not for an
+ * individual gang member. The zio pipeline, however, must be able to
+ * determine the checksum of each of the gang constituents so it
+ * treats the checksum comparison differently than what we need
+ * for l2arc blocks. This prevents us from using the
+ * zio_checksum_error() interface directly. Instead we must call the
+ * zio_checksum_error_impl() so that we can ensure the checksum is
+ * generated using the correct checksum algorithm and accounts for the
+ * logical I/O size and not just a gang fragment.
+ */
+ return (zio_checksum_error_impl(zio->io_spa, zio->io_bp,
+ BP_GET_CHECKSUM(zio->io_bp), zio->io_abd, zio->io_size,
+ zio->io_offset, NULL) == 0);
+}
+
+/*
+ * Given a buf full of data, if ZFS_DEBUG_MODIFY is enabled this computes a
+ * checksum and attaches it to the buf's hdr so that we can ensure that the buf
+ * isn't modified later on. If buf is compressed or there is already a checksum
+ * on the hdr, this is a no-op (we only checksum uncompressed bufs).
+ */
+static void
+arc_cksum_compute(arc_buf_t *buf)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ if (!(zfs_flags & ZFS_DEBUG_MODIFY))
+ return;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ mutex_enter(&buf->b_hdr->b_l1hdr.b_freeze_lock);
+ if (hdr->b_l1hdr.b_freeze_cksum != NULL || ARC_BUF_COMPRESSED(buf)) {
+ mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
+ return;
+ }
+
+ ASSERT(!ARC_BUF_ENCRYPTED(buf));
+ ASSERT(!ARC_BUF_COMPRESSED(buf));
+ hdr->b_l1hdr.b_freeze_cksum = kmem_alloc(sizeof (zio_cksum_t),
+ KM_SLEEP);
+ fletcher_2_native(buf->b_data, arc_buf_size(buf), NULL,
+ hdr->b_l1hdr.b_freeze_cksum);
+ mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
+ arc_buf_watch(buf);
+}
+
+#ifndef _KERNEL
+void
+arc_buf_sigsegv(int sig, siginfo_t *si, void *unused)
+{
+ panic("Got SIGSEGV at address: 0x%lx\n", (long)si->si_addr);
+}
+#endif
+
+/* ARGSUSED */
+static void
+arc_buf_unwatch(arc_buf_t *buf)
+{
+#ifndef _KERNEL
+ if (arc_watch) {
+ ASSERT0(mprotect(buf->b_data, arc_buf_size(buf),
+ PROT_READ | PROT_WRITE));
+ }
+#endif
+}
+
+/* ARGSUSED */
+static void
+arc_buf_watch(arc_buf_t *buf)
+{
+#ifndef _KERNEL
+ if (arc_watch)
+ ASSERT0(mprotect(buf->b_data, arc_buf_size(buf),
+ PROT_READ));
+#endif
+}
+
+static arc_buf_contents_t
+arc_buf_type(arc_buf_hdr_t *hdr)
+{
+ arc_buf_contents_t type;
+ if (HDR_ISTYPE_METADATA(hdr)) {
+ type = ARC_BUFC_METADATA;
+ } else {
+ type = ARC_BUFC_DATA;
+ }
+ VERIFY3U(hdr->b_type, ==, type);
+ return (type);
+}
+
+boolean_t
+arc_is_metadata(arc_buf_t *buf)
+{
+ return (HDR_ISTYPE_METADATA(buf->b_hdr) != 0);
+}
+
+static uint32_t
+arc_bufc_to_flags(arc_buf_contents_t type)
+{
+ switch (type) {
+ case ARC_BUFC_DATA:
+ /* metadata field is 0 if buffer contains normal data */
+ return (0);
+ case ARC_BUFC_METADATA:
+ return (ARC_FLAG_BUFC_METADATA);
+ default:
+ break;
+ }
+ panic("undefined ARC buffer type!");
+ return ((uint32_t)-1);
+}
+
+void
+arc_buf_thaw(arc_buf_t *buf)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+
+ arc_cksum_verify(buf);
+
+ /*
+ * Compressed buffers do not manipulate the b_freeze_cksum.
+ */
+ if (ARC_BUF_COMPRESSED(buf))
+ return;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ arc_cksum_free(hdr);
+ arc_buf_unwatch(buf);
+}
+
+void
+arc_buf_freeze(arc_buf_t *buf)
+{
+ if (!(zfs_flags & ZFS_DEBUG_MODIFY))
+ return;
+
+ if (ARC_BUF_COMPRESSED(buf))
+ return;
+
+ ASSERT(HDR_HAS_L1HDR(buf->b_hdr));
+ arc_cksum_compute(buf);
+}
+
+/*
+ * The arc_buf_hdr_t's b_flags should never be modified directly. Instead,
+ * the following functions should be used to ensure that the flags are
+ * updated in a thread-safe way. When manipulating the flags either
+ * the hash_lock must be held or the hdr must be undiscoverable. This
+ * ensures that we're not racing with any other threads when updating
+ * the flags.
+ */
+static inline void
+arc_hdr_set_flags(arc_buf_hdr_t *hdr, arc_flags_t flags)
+{
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+ hdr->b_flags |= flags;
+}
+
+static inline void
+arc_hdr_clear_flags(arc_buf_hdr_t *hdr, arc_flags_t flags)
+{
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+ hdr->b_flags &= ~flags;
+}
+
+/*
+ * Setting the compression bits in the arc_buf_hdr_t's b_flags is
+ * done in a special way since we have to clear and set bits
+ * at the same time. Consumers that wish to set the compression bits
+ * must use this function to ensure that the flags are updated in
+ * thread-safe manner.
+ */
+static void
+arc_hdr_set_compress(arc_buf_hdr_t *hdr, enum zio_compress cmp)
+{
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+
+ /*
+ * Holes and embedded blocks will always have a psize = 0 so
+ * we ignore the compression of the blkptr and set the
+ * want to uncompress them. Mark them as uncompressed.
+ */
+ if (!zfs_compressed_arc_enabled || HDR_GET_PSIZE(hdr) == 0) {
+ arc_hdr_clear_flags(hdr, ARC_FLAG_COMPRESSED_ARC);
+ ASSERT(!HDR_COMPRESSION_ENABLED(hdr));
+ } else {
+ arc_hdr_set_flags(hdr, ARC_FLAG_COMPRESSED_ARC);
+ ASSERT(HDR_COMPRESSION_ENABLED(hdr));
+ }
+
+ HDR_SET_COMPRESS(hdr, cmp);
+ ASSERT3U(HDR_GET_COMPRESS(hdr), ==, cmp);
+}
+
+/*
+ * Looks for another buf on the same hdr which has the data decompressed, copies
+ * from it, and returns true. If no such buf exists, returns false.
+ */
+static boolean_t
+arc_buf_try_copy_decompressed_data(arc_buf_t *buf)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+ boolean_t copied = B_FALSE;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT3P(buf->b_data, !=, NULL);
+ ASSERT(!ARC_BUF_COMPRESSED(buf));
+
+ for (arc_buf_t *from = hdr->b_l1hdr.b_buf; from != NULL;
+ from = from->b_next) {
+ /* can't use our own data buffer */
+ if (from == buf) {
+ continue;
+ }
+
+ if (!ARC_BUF_COMPRESSED(from)) {
+ bcopy(from->b_data, buf->b_data, arc_buf_size(buf));
+ copied = B_TRUE;
+ break;
+ }
+ }
+
+ /*
+ * There were no decompressed bufs, so there should not be a
+ * checksum on the hdr either.
+ */
+ if (zfs_flags & ZFS_DEBUG_MODIFY)
+ EQUIV(!copied, hdr->b_l1hdr.b_freeze_cksum == NULL);
+
+ return (copied);
+}
+
+/*
+ * Allocates an ARC buf header that's in an evicted & L2-cached state.
+ * This is used during l2arc reconstruction to make empty ARC buffers
+ * which circumvent the regular disk->arc->l2arc path and instead come
+ * into being in the reverse order, i.e. l2arc->arc.
+ */
+static arc_buf_hdr_t *
+arc_buf_alloc_l2only(size_t size, arc_buf_contents_t type, l2arc_dev_t *dev,
+ dva_t dva, uint64_t daddr, int32_t psize, uint64_t birth,
+ enum zio_compress compress, uint8_t complevel, boolean_t protected,
+ boolean_t prefetch)
+{
+ arc_buf_hdr_t *hdr;
+
+ ASSERT(size != 0);
+ hdr = kmem_cache_alloc(hdr_l2only_cache, KM_SLEEP);
+ hdr->b_birth = birth;
+ hdr->b_type = type;
+ hdr->b_flags = 0;
+ arc_hdr_set_flags(hdr, arc_bufc_to_flags(type) | ARC_FLAG_HAS_L2HDR);
+ HDR_SET_LSIZE(hdr, size);
+ HDR_SET_PSIZE(hdr, psize);
+ arc_hdr_set_compress(hdr, compress);
+ hdr->b_complevel = complevel;
+ if (protected)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PROTECTED);
+ if (prefetch)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PREFETCH);
+ hdr->b_spa = spa_load_guid(dev->l2ad_vdev->vdev_spa);
+
+ hdr->b_dva = dva;
+
+ hdr->b_l2hdr.b_dev = dev;
+ hdr->b_l2hdr.b_daddr = daddr;
+
+ return (hdr);
+}
+
+/*
+ * Return the size of the block, b_pabd, that is stored in the arc_buf_hdr_t.
+ */
+static uint64_t
+arc_hdr_size(arc_buf_hdr_t *hdr)
+{
+ uint64_t size;
+
+ if (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF &&
+ HDR_GET_PSIZE(hdr) > 0) {
+ size = HDR_GET_PSIZE(hdr);
+ } else {
+ ASSERT3U(HDR_GET_LSIZE(hdr), !=, 0);
+ size = HDR_GET_LSIZE(hdr);
+ }
+ return (size);
+}
+
+static int
+arc_hdr_authenticate(arc_buf_hdr_t *hdr, spa_t *spa, uint64_t dsobj)
+{
+ int ret;
+ uint64_t csize;
+ uint64_t lsize = HDR_GET_LSIZE(hdr);
+ uint64_t psize = HDR_GET_PSIZE(hdr);
+ void *tmpbuf = NULL;
+ abd_t *abd = hdr->b_l1hdr.b_pabd;
+
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+ ASSERT(HDR_AUTHENTICATED(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+
+ /*
+ * The MAC is calculated on the compressed data that is stored on disk.
+ * However, if compressed arc is disabled we will only have the
+ * decompressed data available to us now. Compress it into a temporary
+ * abd so we can verify the MAC. The performance overhead of this will
+ * be relatively low, since most objects in an encrypted objset will
+ * be encrypted (instead of authenticated) anyway.
+ */
+ if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
+ !HDR_COMPRESSION_ENABLED(hdr)) {
+ tmpbuf = zio_buf_alloc(lsize);
+ abd = abd_get_from_buf(tmpbuf, lsize);
+ abd_take_ownership_of_buf(abd, B_TRUE);
+ csize = zio_compress_data(HDR_GET_COMPRESS(hdr),
+ hdr->b_l1hdr.b_pabd, tmpbuf, lsize, hdr->b_complevel);
+ ASSERT3U(csize, <=, psize);
+ abd_zero_off(abd, csize, psize - csize);
+ }
+
+ /*
+ * Authentication is best effort. We authenticate whenever the key is
+ * available. If we succeed we clear ARC_FLAG_NOAUTH.
+ */
+ if (hdr->b_crypt_hdr.b_ot == DMU_OT_OBJSET) {
+ ASSERT3U(HDR_GET_COMPRESS(hdr), ==, ZIO_COMPRESS_OFF);
+ ASSERT3U(lsize, ==, psize);
+ ret = spa_do_crypt_objset_mac_abd(B_FALSE, spa, dsobj, abd,
+ psize, hdr->b_l1hdr.b_byteswap != DMU_BSWAP_NUMFUNCS);
+ } else {
+ ret = spa_do_crypt_mac_abd(B_FALSE, spa, dsobj, abd, psize,
+ hdr->b_crypt_hdr.b_mac);
+ }
+
+ if (ret == 0)
+ arc_hdr_clear_flags(hdr, ARC_FLAG_NOAUTH);
+ else if (ret != ENOENT)
+ goto error;
+
+ if (tmpbuf != NULL)
+ abd_free(abd);
+
+ return (0);
+
+error:
+ if (tmpbuf != NULL)
+ abd_free(abd);
+
+ return (ret);
+}
+
+/*
+ * This function will take a header that only has raw encrypted data in
+ * b_crypt_hdr.b_rabd and decrypt it into a new buffer which is stored in
+ * b_l1hdr.b_pabd. If designated in the header flags, this function will
+ * also decompress the data.
+ */
+static int
+arc_hdr_decrypt(arc_buf_hdr_t *hdr, spa_t *spa, const zbookmark_phys_t *zb)
+{
+ int ret;
+ abd_t *cabd = NULL;
+ void *tmp = NULL;
+ boolean_t no_crypt = B_FALSE;
+ boolean_t bswap = (hdr->b_l1hdr.b_byteswap != DMU_BSWAP_NUMFUNCS);
+
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+ ASSERT(HDR_ENCRYPTED(hdr));
+
+ arc_hdr_alloc_abd(hdr, ARC_HDR_DO_ADAPT);
+
+ ret = spa_do_crypt_abd(B_FALSE, spa, zb, hdr->b_crypt_hdr.b_ot,
+ B_FALSE, bswap, hdr->b_crypt_hdr.b_salt, hdr->b_crypt_hdr.b_iv,
+ hdr->b_crypt_hdr.b_mac, HDR_GET_PSIZE(hdr), hdr->b_l1hdr.b_pabd,
+ hdr->b_crypt_hdr.b_rabd, &no_crypt);
+ if (ret != 0)
+ goto error;
+
+ if (no_crypt) {
+ abd_copy(hdr->b_l1hdr.b_pabd, hdr->b_crypt_hdr.b_rabd,
+ HDR_GET_PSIZE(hdr));
+ }
+
+ /*
+ * If this header has disabled arc compression but the b_pabd is
+ * compressed after decrypting it, we need to decompress the newly
+ * decrypted data.
+ */
+ if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
+ !HDR_COMPRESSION_ENABLED(hdr)) {
+ /*
+ * We want to make sure that we are correctly honoring the
+ * zfs_abd_scatter_enabled setting, so we allocate an abd here
+ * and then loan a buffer from it, rather than allocating a
+ * linear buffer and wrapping it in an abd later.
+ */
+ cabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr, B_TRUE);
+ tmp = abd_borrow_buf(cabd, arc_hdr_size(hdr));
+
+ ret = zio_decompress_data(HDR_GET_COMPRESS(hdr),
+ hdr->b_l1hdr.b_pabd, tmp, HDR_GET_PSIZE(hdr),
+ HDR_GET_LSIZE(hdr), &hdr->b_complevel);
+ if (ret != 0) {
+ abd_return_buf(cabd, tmp, arc_hdr_size(hdr));
+ goto error;
+ }
+
+ abd_return_buf_copy(cabd, tmp, arc_hdr_size(hdr));
+ arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
+ arc_hdr_size(hdr), hdr);
+ hdr->b_l1hdr.b_pabd = cabd;
+ }
+
+ return (0);
+
+error:
+ arc_hdr_free_abd(hdr, B_FALSE);
+ if (cabd != NULL)
+ arc_free_data_buf(hdr, cabd, arc_hdr_size(hdr), hdr);
+
+ return (ret);
+}
+
+/*
+ * This function is called during arc_buf_fill() to prepare the header's
+ * abd plaintext pointer for use. This involves authenticated protected
+ * data and decrypting encrypted data into the plaintext abd.
+ */
+static int
+arc_fill_hdr_crypt(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, spa_t *spa,
+ const zbookmark_phys_t *zb, boolean_t noauth)
+{
+ int ret;
+
+ ASSERT(HDR_PROTECTED(hdr));
+
+ if (hash_lock != NULL)
+ mutex_enter(hash_lock);
+
+ if (HDR_NOAUTH(hdr) && !noauth) {
+ /*
+ * The caller requested authenticated data but our data has
+ * not been authenticated yet. Verify the MAC now if we can.
+ */
+ ret = arc_hdr_authenticate(hdr, spa, zb->zb_objset);
+ if (ret != 0)
+ goto error;
+ } else if (HDR_HAS_RABD(hdr) && hdr->b_l1hdr.b_pabd == NULL) {
+ /*
+ * If we only have the encrypted version of the data, but the
+ * unencrypted version was requested we take this opportunity
+ * to store the decrypted version in the header for future use.
+ */
+ ret = arc_hdr_decrypt(hdr, spa, zb);
+ if (ret != 0)
+ goto error;
+ }
+
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+
+ return (0);
+
+error:
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+
+ return (ret);
+}
+
+/*
+ * This function is used by the dbuf code to decrypt bonus buffers in place.
+ * The dbuf code itself doesn't have any locking for decrypting a shared dnode
+ * block, so we use the hash lock here to protect against concurrent calls to
+ * arc_buf_fill().
+ */
+static void
+arc_buf_untransform_in_place(arc_buf_t *buf, kmutex_t *hash_lock)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT(HDR_ENCRYPTED(hdr));
+ ASSERT3U(hdr->b_crypt_hdr.b_ot, ==, DMU_OT_DNODE);
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+
+ zio_crypt_copy_dnode_bonus(hdr->b_l1hdr.b_pabd, buf->b_data,
+ arc_buf_size(buf));
+ buf->b_flags &= ~ARC_BUF_FLAG_ENCRYPTED;
+ buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
+ hdr->b_crypt_hdr.b_ebufcnt -= 1;
+}
+
+/*
+ * Given a buf that has a data buffer attached to it, this function will
+ * efficiently fill the buf with data of the specified compression setting from
+ * the hdr and update the hdr's b_freeze_cksum if necessary. If the buf and hdr
+ * are already sharing a data buf, no copy is performed.
+ *
+ * If the buf is marked as compressed but uncompressed data was requested, this
+ * will allocate a new data buffer for the buf, remove that flag, and fill the
+ * buf with uncompressed data. You can't request a compressed buf on a hdr with
+ * uncompressed data, and (since we haven't added support for it yet) if you
+ * want compressed data your buf must already be marked as compressed and have
+ * the correct-sized data buffer.
+ */
+static int
+arc_buf_fill(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
+ arc_fill_flags_t flags)
+{
+ int error = 0;
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+ boolean_t hdr_compressed =
+ (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF);
+ boolean_t compressed = (flags & ARC_FILL_COMPRESSED) != 0;
+ boolean_t encrypted = (flags & ARC_FILL_ENCRYPTED) != 0;
+ dmu_object_byteswap_t bswap = hdr->b_l1hdr.b_byteswap;
+ kmutex_t *hash_lock = (flags & ARC_FILL_LOCKED) ? NULL : HDR_LOCK(hdr);
+
+ ASSERT3P(buf->b_data, !=, NULL);
+ IMPLY(compressed, hdr_compressed || ARC_BUF_ENCRYPTED(buf));
+ IMPLY(compressed, ARC_BUF_COMPRESSED(buf));
+ IMPLY(encrypted, HDR_ENCRYPTED(hdr));
+ IMPLY(encrypted, ARC_BUF_ENCRYPTED(buf));
+ IMPLY(encrypted, ARC_BUF_COMPRESSED(buf));
+ IMPLY(encrypted, !ARC_BUF_SHARED(buf));
+
+ /*
+ * If the caller wanted encrypted data we just need to copy it from
+ * b_rabd and potentially byteswap it. We won't be able to do any
+ * further transforms on it.
+ */
+ if (encrypted) {
+ ASSERT(HDR_HAS_RABD(hdr));
+ abd_copy_to_buf(buf->b_data, hdr->b_crypt_hdr.b_rabd,
+ HDR_GET_PSIZE(hdr));
+ goto byteswap;
+ }
+
+ /*
+ * Adjust encrypted and authenticated headers to accommodate
+ * the request if needed. Dnode blocks (ARC_FILL_IN_PLACE) are
+ * allowed to fail decryption due to keys not being loaded
+ * without being marked as an IO error.
+ */
+ if (HDR_PROTECTED(hdr)) {
+ error = arc_fill_hdr_crypt(hdr, hash_lock, spa,
+ zb, !!(flags & ARC_FILL_NOAUTH));
+ if (error == EACCES && (flags & ARC_FILL_IN_PLACE) != 0) {
+ return (error);
+ } else if (error != 0) {
+ if (hash_lock != NULL)
+ mutex_enter(hash_lock);
+ arc_hdr_set_flags(hdr, ARC_FLAG_IO_ERROR);
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+ return (error);
+ }
+ }
+
+ /*
+ * There is a special case here for dnode blocks which are
+ * decrypting their bonus buffers. These blocks may request to
+ * be decrypted in-place. This is necessary because there may
+ * be many dnodes pointing into this buffer and there is
+ * currently no method to synchronize replacing the backing
+ * b_data buffer and updating all of the pointers. Here we use
+ * the hash lock to ensure there are no races. If the need
+ * arises for other types to be decrypted in-place, they must
+ * add handling here as well.
+ */
+ if ((flags & ARC_FILL_IN_PLACE) != 0) {
+ ASSERT(!hdr_compressed);
+ ASSERT(!compressed);
+ ASSERT(!encrypted);
+
+ if (HDR_ENCRYPTED(hdr) && ARC_BUF_ENCRYPTED(buf)) {
+ ASSERT3U(hdr->b_crypt_hdr.b_ot, ==, DMU_OT_DNODE);
+
+ if (hash_lock != NULL)
+ mutex_enter(hash_lock);
+ arc_buf_untransform_in_place(buf, hash_lock);
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+
+ /* Compute the hdr's checksum if necessary */
+ arc_cksum_compute(buf);
+ }
+
+ return (0);
+ }
+
+ if (hdr_compressed == compressed) {
+ if (!arc_buf_is_shared(buf)) {
+ abd_copy_to_buf(buf->b_data, hdr->b_l1hdr.b_pabd,
+ arc_buf_size(buf));
+ }
+ } else {
+ ASSERT(hdr_compressed);
+ ASSERT(!compressed);
+ ASSERT3U(HDR_GET_LSIZE(hdr), !=, HDR_GET_PSIZE(hdr));
+
+ /*
+ * If the buf is sharing its data with the hdr, unlink it and
+ * allocate a new data buffer for the buf.
+ */
+ if (arc_buf_is_shared(buf)) {
+ ASSERT(ARC_BUF_COMPRESSED(buf));
+
+ /* We need to give the buf its own b_data */
+ buf->b_flags &= ~ARC_BUF_FLAG_SHARED;
+ buf->b_data =
+ arc_get_data_buf(hdr, HDR_GET_LSIZE(hdr), buf);
+ arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
+
+ /* Previously overhead was 0; just add new overhead */
+ ARCSTAT_INCR(arcstat_overhead_size, HDR_GET_LSIZE(hdr));
+ } else if (ARC_BUF_COMPRESSED(buf)) {
+ /* We need to reallocate the buf's b_data */
+ arc_free_data_buf(hdr, buf->b_data, HDR_GET_PSIZE(hdr),
+ buf);
+ buf->b_data =
+ arc_get_data_buf(hdr, HDR_GET_LSIZE(hdr), buf);
+
+ /* We increased the size of b_data; update overhead */
+ ARCSTAT_INCR(arcstat_overhead_size,
+ HDR_GET_LSIZE(hdr) - HDR_GET_PSIZE(hdr));
+ }
+
+ /*
+ * Regardless of the buf's previous compression settings, it
+ * should not be compressed at the end of this function.
+ */
+ buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
+
+ /*
+ * Try copying the data from another buf which already has a
+ * decompressed version. If that's not possible, it's time to
+ * bite the bullet and decompress the data from the hdr.
+ */
+ if (arc_buf_try_copy_decompressed_data(buf)) {
+ /* Skip byteswapping and checksumming (already done) */
+ return (0);
+ } else {
+ error = zio_decompress_data(HDR_GET_COMPRESS(hdr),
+ hdr->b_l1hdr.b_pabd, buf->b_data,
+ HDR_GET_PSIZE(hdr), HDR_GET_LSIZE(hdr),
+ &hdr->b_complevel);
+
+ /*
+ * Absent hardware errors or software bugs, this should
+ * be impossible, but log it anyway so we can debug it.
+ */
+ if (error != 0) {
+ zfs_dbgmsg(
+ "hdr %px, compress %d, psize %d, lsize %d",
+ hdr, arc_hdr_get_compress(hdr),
+ HDR_GET_PSIZE(hdr), HDR_GET_LSIZE(hdr));
+ if (hash_lock != NULL)
+ mutex_enter(hash_lock);
+ arc_hdr_set_flags(hdr, ARC_FLAG_IO_ERROR);
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+ return (SET_ERROR(EIO));
+ }
+ }
+ }
+
+byteswap:
+ /* Byteswap the buf's data if necessary */
+ if (bswap != DMU_BSWAP_NUMFUNCS) {
+ ASSERT(!HDR_SHARED_DATA(hdr));
+ ASSERT3U(bswap, <, DMU_BSWAP_NUMFUNCS);
+ dmu_ot_byteswap[bswap].ob_func(buf->b_data, HDR_GET_LSIZE(hdr));
+ }
+
+ /* Compute the hdr's checksum if necessary */
+ arc_cksum_compute(buf);
+
+ return (0);
+}
+
+/*
+ * If this function is being called to decrypt an encrypted buffer or verify an
+ * authenticated one, the key must be loaded and a mapping must be made
+ * available in the keystore via spa_keystore_create_mapping() or one of its
+ * callers.
+ */
+int
+arc_untransform(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
+ boolean_t in_place)
+{
+ int ret;
+ arc_fill_flags_t flags = 0;
+
+ if (in_place)
+ flags |= ARC_FILL_IN_PLACE;
+
+ ret = arc_buf_fill(buf, spa, zb, flags);
+ if (ret == ECKSUM) {
+ /*
+ * Convert authentication and decryption errors to EIO
+ * (and generate an ereport) before leaving the ARC.
+ */
+ ret = SET_ERROR(EIO);
+ spa_log_error(spa, zb);
+ zfs_ereport_post(FM_EREPORT_ZFS_AUTHENTICATION,
+ spa, NULL, zb, NULL, 0, 0);
+ }
+
+ return (ret);
+}
+
+/*
+ * Increment the amount of evictable space in the arc_state_t's refcount.
+ * We account for the space used by the hdr and the arc buf individually
+ * so that we can add and remove them from the refcount individually.
+ */
+static void
+arc_evictable_space_increment(arc_buf_hdr_t *hdr, arc_state_t *state)
+{
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ if (GHOST_STATE(state)) {
+ ASSERT0(hdr->b_l1hdr.b_bufcnt);
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ (void) zfs_refcount_add_many(&state->arcs_esize[type],
+ HDR_GET_LSIZE(hdr), hdr);
+ return;
+ }
+
+ ASSERT(!GHOST_STATE(state));
+ if (hdr->b_l1hdr.b_pabd != NULL) {
+ (void) zfs_refcount_add_many(&state->arcs_esize[type],
+ arc_hdr_size(hdr), hdr);
+ }
+ if (HDR_HAS_RABD(hdr)) {
+ (void) zfs_refcount_add_many(&state->arcs_esize[type],
+ HDR_GET_PSIZE(hdr), hdr);
+ }
+
+ for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
+ buf = buf->b_next) {
+ if (arc_buf_is_shared(buf))
+ continue;
+ (void) zfs_refcount_add_many(&state->arcs_esize[type],
+ arc_buf_size(buf), buf);
+ }
+}
+
+/*
+ * Decrement the amount of evictable space in the arc_state_t's refcount.
+ * We account for the space used by the hdr and the arc buf individually
+ * so that we can add and remove them from the refcount individually.
+ */
+static void
+arc_evictable_space_decrement(arc_buf_hdr_t *hdr, arc_state_t *state)
+{
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ if (GHOST_STATE(state)) {
+ ASSERT0(hdr->b_l1hdr.b_bufcnt);
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ (void) zfs_refcount_remove_many(&state->arcs_esize[type],
+ HDR_GET_LSIZE(hdr), hdr);
+ return;
+ }
+
+ ASSERT(!GHOST_STATE(state));
+ if (hdr->b_l1hdr.b_pabd != NULL) {
+ (void) zfs_refcount_remove_many(&state->arcs_esize[type],
+ arc_hdr_size(hdr), hdr);
+ }
+ if (HDR_HAS_RABD(hdr)) {
+ (void) zfs_refcount_remove_many(&state->arcs_esize[type],
+ HDR_GET_PSIZE(hdr), hdr);
+ }
+
+ for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
+ buf = buf->b_next) {
+ if (arc_buf_is_shared(buf))
+ continue;
+ (void) zfs_refcount_remove_many(&state->arcs_esize[type],
+ arc_buf_size(buf), buf);
+ }
+}
+
+/*
+ * Add a reference to this hdr indicating that someone is actively
+ * referencing that memory. When the refcount transitions from 0 to 1,
+ * we remove it from the respective arc_state_t list to indicate that
+ * it is not evictable.
+ */
+static void
+add_reference(arc_buf_hdr_t *hdr, void *tag)
+{
+ arc_state_t *state;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ if (!HDR_EMPTY(hdr) && !MUTEX_HELD(HDR_LOCK(hdr))) {
+ ASSERT(hdr->b_l1hdr.b_state == arc_anon);
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ }
+
+ state = hdr->b_l1hdr.b_state;
+
+ if ((zfs_refcount_add(&hdr->b_l1hdr.b_refcnt, tag) == 1) &&
+ (state != arc_anon)) {
+ /* We don't use the L2-only state list. */
+ if (state != arc_l2c_only) {
+ multilist_remove(state->arcs_list[arc_buf_type(hdr)],
+ hdr);
+ arc_evictable_space_decrement(hdr, state);
+ }
+ /* remove the prefetch flag if we get a reference */
+ arc_hdr_clear_flags(hdr, ARC_FLAG_PREFETCH);
+ }
+}
+
+/*
+ * Remove a reference from this hdr. When the reference transitions from
+ * 1 to 0 and we're not anonymous, then we add this hdr to the arc_state_t's
+ * list making it eligible for eviction.
+ */
+static int
+remove_reference(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, void *tag)
+{
+ int cnt;
+ arc_state_t *state = hdr->b_l1hdr.b_state;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT(state == arc_anon || MUTEX_HELD(hash_lock));
+ ASSERT(!GHOST_STATE(state));
+
+ /*
+ * arc_l2c_only counts as a ghost state so we don't need to explicitly
+ * check to prevent usage of the arc_l2c_only list.
+ */
+ if (((cnt = zfs_refcount_remove(&hdr->b_l1hdr.b_refcnt, tag)) == 0) &&
+ (state != arc_anon)) {
+ multilist_insert(state->arcs_list[arc_buf_type(hdr)], hdr);
+ ASSERT3U(hdr->b_l1hdr.b_bufcnt, >, 0);
+ arc_evictable_space_increment(hdr, state);
+ }
+ return (cnt);
+}
+
+/*
+ * Returns detailed information about a specific arc buffer. When the
+ * state_index argument is set the function will calculate the arc header
+ * list position for its arc state. Since this requires a linear traversal
+ * callers are strongly encourage not to do this. However, it can be helpful
+ * for targeted analysis so the functionality is provided.
+ */
+void
+arc_buf_info(arc_buf_t *ab, arc_buf_info_t *abi, int state_index)
+{
+ arc_buf_hdr_t *hdr = ab->b_hdr;
+ l1arc_buf_hdr_t *l1hdr = NULL;
+ l2arc_buf_hdr_t *l2hdr = NULL;
+ arc_state_t *state = NULL;
+
+ memset(abi, 0, sizeof (arc_buf_info_t));
+
+ if (hdr == NULL)
+ return;
+
+ abi->abi_flags = hdr->b_flags;
+
+ if (HDR_HAS_L1HDR(hdr)) {
+ l1hdr = &hdr->b_l1hdr;
+ state = l1hdr->b_state;
+ }
+ if (HDR_HAS_L2HDR(hdr))
+ l2hdr = &hdr->b_l2hdr;
+
+ if (l1hdr) {
+ abi->abi_bufcnt = l1hdr->b_bufcnt;
+ abi->abi_access = l1hdr->b_arc_access;
+ abi->abi_mru_hits = l1hdr->b_mru_hits;
+ abi->abi_mru_ghost_hits = l1hdr->b_mru_ghost_hits;
+ abi->abi_mfu_hits = l1hdr->b_mfu_hits;
+ abi->abi_mfu_ghost_hits = l1hdr->b_mfu_ghost_hits;
+ abi->abi_holds = zfs_refcount_count(&l1hdr->b_refcnt);
+ }
+
+ if (l2hdr) {
+ abi->abi_l2arc_dattr = l2hdr->b_daddr;
+ abi->abi_l2arc_hits = l2hdr->b_hits;
+ }
+
+ abi->abi_state_type = state ? state->arcs_state : ARC_STATE_ANON;
+ abi->abi_state_contents = arc_buf_type(hdr);
+ abi->abi_size = arc_hdr_size(hdr);
+}
+
+/*
+ * Move the supplied buffer to the indicated state. The hash lock
+ * for the buffer must be held by the caller.
+ */
+static void
+arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr,
+ kmutex_t *hash_lock)
+{
+ arc_state_t *old_state;
+ int64_t refcnt;
+ uint32_t bufcnt;
+ boolean_t update_old, update_new;
+ arc_buf_contents_t buftype = arc_buf_type(hdr);
+
+ /*
+ * We almost always have an L1 hdr here, since we call arc_hdr_realloc()
+ * in arc_read() when bringing a buffer out of the L2ARC. However, the
+ * L1 hdr doesn't always exist when we change state to arc_anon before
+ * destroying a header, in which case reallocating to add the L1 hdr is
+ * pointless.
+ */
+ if (HDR_HAS_L1HDR(hdr)) {
+ old_state = hdr->b_l1hdr.b_state;
+ refcnt = zfs_refcount_count(&hdr->b_l1hdr.b_refcnt);
+ bufcnt = hdr->b_l1hdr.b_bufcnt;
+ update_old = (bufcnt > 0 || hdr->b_l1hdr.b_pabd != NULL ||
+ HDR_HAS_RABD(hdr));
+ } else {
+ old_state = arc_l2c_only;
+ refcnt = 0;
+ bufcnt = 0;
+ update_old = B_FALSE;
+ }
+ update_new = update_old;
+
+ ASSERT(MUTEX_HELD(hash_lock));
+ ASSERT3P(new_state, !=, old_state);
+ ASSERT(!GHOST_STATE(new_state) || bufcnt == 0);
+ ASSERT(old_state != arc_anon || bufcnt <= 1);
+
+ /*
+ * If this buffer is evictable, transfer it from the
+ * old state list to the new state list.
+ */
+ if (refcnt == 0) {
+ if (old_state != arc_anon && old_state != arc_l2c_only) {
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ multilist_remove(old_state->arcs_list[buftype], hdr);
+
+ if (GHOST_STATE(old_state)) {
+ ASSERT0(bufcnt);
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ update_old = B_TRUE;
+ }
+ arc_evictable_space_decrement(hdr, old_state);
+ }
+ if (new_state != arc_anon && new_state != arc_l2c_only) {
+ /*
+ * An L1 header always exists here, since if we're
+ * moving to some L1-cached state (i.e. not l2c_only or
+ * anonymous), we realloc the header to add an L1hdr
+ * beforehand.
+ */
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ multilist_insert(new_state->arcs_list[buftype], hdr);
+
+ if (GHOST_STATE(new_state)) {
+ ASSERT0(bufcnt);
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ update_new = B_TRUE;
+ }
+ arc_evictable_space_increment(hdr, new_state);
+ }
+ }
+
+ ASSERT(!HDR_EMPTY(hdr));
+ if (new_state == arc_anon && HDR_IN_HASH_TABLE(hdr))
+ buf_hash_remove(hdr);
+
+ /* adjust state sizes (ignore arc_l2c_only) */
+
+ if (update_new && new_state != arc_l2c_only) {
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ if (GHOST_STATE(new_state)) {
+ ASSERT0(bufcnt);
+
+ /*
+ * When moving a header to a ghost state, we first
+ * remove all arc buffers. Thus, we'll have a
+ * bufcnt of zero, and no arc buffer to use for
+ * the reference. As a result, we use the arc
+ * header pointer for the reference.
+ */
+ (void) zfs_refcount_add_many(&new_state->arcs_size,
+ HDR_GET_LSIZE(hdr), hdr);
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ } else {
+ uint32_t buffers = 0;
+
+ /*
+ * Each individual buffer holds a unique reference,
+ * thus we must remove each of these references one
+ * at a time.
+ */
+ for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
+ buf = buf->b_next) {
+ ASSERT3U(bufcnt, !=, 0);
+ buffers++;
+
+ /*
+ * When the arc_buf_t is sharing the data
+ * block with the hdr, the owner of the
+ * reference belongs to the hdr. Only
+ * add to the refcount if the arc_buf_t is
+ * not shared.
+ */
+ if (arc_buf_is_shared(buf))
+ continue;
+
+ (void) zfs_refcount_add_many(
+ &new_state->arcs_size,
+ arc_buf_size(buf), buf);
+ }
+ ASSERT3U(bufcnt, ==, buffers);
+
+ if (hdr->b_l1hdr.b_pabd != NULL) {
+ (void) zfs_refcount_add_many(
+ &new_state->arcs_size,
+ arc_hdr_size(hdr), hdr);
+ }
+
+ if (HDR_HAS_RABD(hdr)) {
+ (void) zfs_refcount_add_many(
+ &new_state->arcs_size,
+ HDR_GET_PSIZE(hdr), hdr);
+ }
+ }
+ }
+
+ if (update_old && old_state != arc_l2c_only) {
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ if (GHOST_STATE(old_state)) {
+ ASSERT0(bufcnt);
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+
+ /*
+ * When moving a header off of a ghost state,
+ * the header will not contain any arc buffers.
+ * We use the arc header pointer for the reference
+ * which is exactly what we did when we put the
+ * header on the ghost state.
+ */
+
+ (void) zfs_refcount_remove_many(&old_state->arcs_size,
+ HDR_GET_LSIZE(hdr), hdr);
+ } else {
+ uint32_t buffers = 0;
+
+ /*
+ * Each individual buffer holds a unique reference,
+ * thus we must remove each of these references one
+ * at a time.
+ */
+ for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
+ buf = buf->b_next) {
+ ASSERT3U(bufcnt, !=, 0);
+ buffers++;
+
+ /*
+ * When the arc_buf_t is sharing the data
+ * block with the hdr, the owner of the
+ * reference belongs to the hdr. Only
+ * add to the refcount if the arc_buf_t is
+ * not shared.
+ */
+ if (arc_buf_is_shared(buf))
+ continue;
+
+ (void) zfs_refcount_remove_many(
+ &old_state->arcs_size, arc_buf_size(buf),
+ buf);
+ }
+ ASSERT3U(bufcnt, ==, buffers);
+ ASSERT(hdr->b_l1hdr.b_pabd != NULL ||
+ HDR_HAS_RABD(hdr));
+
+ if (hdr->b_l1hdr.b_pabd != NULL) {
+ (void) zfs_refcount_remove_many(
+ &old_state->arcs_size, arc_hdr_size(hdr),
+ hdr);
+ }
+
+ if (HDR_HAS_RABD(hdr)) {
+ (void) zfs_refcount_remove_many(
+ &old_state->arcs_size, HDR_GET_PSIZE(hdr),
+ hdr);
+ }
+ }
+ }
+
+ if (HDR_HAS_L1HDR(hdr))
+ hdr->b_l1hdr.b_state = new_state;
+
+ /*
+ * L2 headers should never be on the L2 state list since they don't
+ * have L1 headers allocated.
+ */
+ ASSERT(multilist_is_empty(arc_l2c_only->arcs_list[ARC_BUFC_DATA]) &&
+ multilist_is_empty(arc_l2c_only->arcs_list[ARC_BUFC_METADATA]));
+}
+
+void
+arc_space_consume(uint64_t space, arc_space_type_t type)
+{
+ ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES);
+
+ switch (type) {
+ default:
+ break;
+ case ARC_SPACE_DATA:
+ aggsum_add(&astat_data_size, space);
+ break;
+ case ARC_SPACE_META:
+ aggsum_add(&astat_metadata_size, space);
+ break;
+ case ARC_SPACE_BONUS:
+ aggsum_add(&astat_bonus_size, space);
+ break;
+ case ARC_SPACE_DNODE:
+ aggsum_add(&astat_dnode_size, space);
+ break;
+ case ARC_SPACE_DBUF:
+ aggsum_add(&astat_dbuf_size, space);
+ break;
+ case ARC_SPACE_HDRS:
+ aggsum_add(&astat_hdr_size, space);
+ break;
+ case ARC_SPACE_L2HDRS:
+ aggsum_add(&astat_l2_hdr_size, space);
+ break;
+ case ARC_SPACE_ABD_CHUNK_WASTE:
+ /*
+ * Note: this includes space wasted by all scatter ABD's, not
+ * just those allocated by the ARC. But the vast majority of
+ * scatter ABD's come from the ARC, because other users are
+ * very short-lived.
+ */
+ aggsum_add(&astat_abd_chunk_waste_size, space);
+ break;
+ }
+
+ if (type != ARC_SPACE_DATA && type != ARC_SPACE_ABD_CHUNK_WASTE)
+ aggsum_add(&arc_meta_used, space);
+
+ aggsum_add(&arc_size, space);
+}
+
+void
+arc_space_return(uint64_t space, arc_space_type_t type)
+{
+ ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES);
+
+ switch (type) {
+ default:
+ break;
+ case ARC_SPACE_DATA:
+ aggsum_add(&astat_data_size, -space);
+ break;
+ case ARC_SPACE_META:
+ aggsum_add(&astat_metadata_size, -space);
+ break;
+ case ARC_SPACE_BONUS:
+ aggsum_add(&astat_bonus_size, -space);
+ break;
+ case ARC_SPACE_DNODE:
+ aggsum_add(&astat_dnode_size, -space);
+ break;
+ case ARC_SPACE_DBUF:
+ aggsum_add(&astat_dbuf_size, -space);
+ break;
+ case ARC_SPACE_HDRS:
+ aggsum_add(&astat_hdr_size, -space);
+ break;
+ case ARC_SPACE_L2HDRS:
+ aggsum_add(&astat_l2_hdr_size, -space);
+ break;
+ case ARC_SPACE_ABD_CHUNK_WASTE:
+ aggsum_add(&astat_abd_chunk_waste_size, -space);
+ break;
+ }
+
+ if (type != ARC_SPACE_DATA && type != ARC_SPACE_ABD_CHUNK_WASTE) {
+ ASSERT(aggsum_compare(&arc_meta_used, space) >= 0);
+ /*
+ * We use the upper bound here rather than the precise value
+ * because the arc_meta_max value doesn't need to be
+ * precise. It's only consumed by humans via arcstats.
+ */
+ if (arc_meta_max < aggsum_upper_bound(&arc_meta_used))
+ arc_meta_max = aggsum_upper_bound(&arc_meta_used);
+ aggsum_add(&arc_meta_used, -space);
+ }
+
+ ASSERT(aggsum_compare(&arc_size, space) >= 0);
+ aggsum_add(&arc_size, -space);
+}
+
+/*
+ * Given a hdr and a buf, returns whether that buf can share its b_data buffer
+ * with the hdr's b_pabd.
+ */
+static boolean_t
+arc_can_share(arc_buf_hdr_t *hdr, arc_buf_t *buf)
+{
+ /*
+ * The criteria for sharing a hdr's data are:
+ * 1. the buffer is not encrypted
+ * 2. the hdr's compression matches the buf's compression
+ * 3. the hdr doesn't need to be byteswapped
+ * 4. the hdr isn't already being shared
+ * 5. the buf is either compressed or it is the last buf in the hdr list
+ *
+ * Criterion #5 maintains the invariant that shared uncompressed
+ * bufs must be the final buf in the hdr's b_buf list. Reading this, you
+ * might ask, "if a compressed buf is allocated first, won't that be the
+ * last thing in the list?", but in that case it's impossible to create
+ * a shared uncompressed buf anyway (because the hdr must be compressed
+ * to have the compressed buf). You might also think that #3 is
+ * sufficient to make this guarantee, however it's possible
+ * (specifically in the rare L2ARC write race mentioned in
+ * arc_buf_alloc_impl()) there will be an existing uncompressed buf that
+ * is shareable, but wasn't at the time of its allocation. Rather than
+ * allow a new shared uncompressed buf to be created and then shuffle
+ * the list around to make it the last element, this simply disallows
+ * sharing if the new buf isn't the first to be added.
+ */
+ ASSERT3P(buf->b_hdr, ==, hdr);
+ boolean_t hdr_compressed =
+ arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF;
+ boolean_t buf_compressed = ARC_BUF_COMPRESSED(buf) != 0;
+ return (!ARC_BUF_ENCRYPTED(buf) &&
+ buf_compressed == hdr_compressed &&
+ hdr->b_l1hdr.b_byteswap == DMU_BSWAP_NUMFUNCS &&
+ !HDR_SHARED_DATA(hdr) &&
+ (ARC_BUF_LAST(buf) || ARC_BUF_COMPRESSED(buf)));
+}
+
+/*
+ * Allocate a buf for this hdr. If you care about the data that's in the hdr,
+ * or if you want a compressed buffer, pass those flags in. Returns 0 if the
+ * copy was made successfully, or an error code otherwise.
+ */
+static int
+arc_buf_alloc_impl(arc_buf_hdr_t *hdr, spa_t *spa, const zbookmark_phys_t *zb,
+ void *tag, boolean_t encrypted, boolean_t compressed, boolean_t noauth,
+ boolean_t fill, arc_buf_t **ret)
+{
+ arc_buf_t *buf;
+ arc_fill_flags_t flags = ARC_FILL_LOCKED;
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT3U(HDR_GET_LSIZE(hdr), >, 0);
+ VERIFY(hdr->b_type == ARC_BUFC_DATA ||
+ hdr->b_type == ARC_BUFC_METADATA);
+ ASSERT3P(ret, !=, NULL);
+ ASSERT3P(*ret, ==, NULL);
+ IMPLY(encrypted, compressed);
+
+ hdr->b_l1hdr.b_mru_hits = 0;
+ hdr->b_l1hdr.b_mru_ghost_hits = 0;
+ hdr->b_l1hdr.b_mfu_hits = 0;
+ hdr->b_l1hdr.b_mfu_ghost_hits = 0;
+ hdr->b_l1hdr.b_l2_hits = 0;
+
+ buf = *ret = kmem_cache_alloc(buf_cache, KM_PUSHPAGE);
+ buf->b_hdr = hdr;
+ buf->b_data = NULL;
+ buf->b_next = hdr->b_l1hdr.b_buf;
+ buf->b_flags = 0;
+
+ add_reference(hdr, tag);
+
+ /*
+ * We're about to change the hdr's b_flags. We must either
+ * hold the hash_lock or be undiscoverable.
+ */
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+
+ /*
+ * Only honor requests for compressed bufs if the hdr is actually
+ * compressed. This must be overridden if the buffer is encrypted since
+ * encrypted buffers cannot be decompressed.
+ */
+ if (encrypted) {
+ buf->b_flags |= ARC_BUF_FLAG_COMPRESSED;
+ buf->b_flags |= ARC_BUF_FLAG_ENCRYPTED;
+ flags |= ARC_FILL_COMPRESSED | ARC_FILL_ENCRYPTED;
+ } else if (compressed &&
+ arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF) {
+ buf->b_flags |= ARC_BUF_FLAG_COMPRESSED;
+ flags |= ARC_FILL_COMPRESSED;
+ }
+
+ if (noauth) {
+ ASSERT0(encrypted);
+ flags |= ARC_FILL_NOAUTH;
+ }
+
+ /*
+ * If the hdr's data can be shared then we share the data buffer and
+ * set the appropriate bit in the hdr's b_flags to indicate the hdr is
+ * sharing it's b_pabd with the arc_buf_t. Otherwise, we allocate a new
+ * buffer to store the buf's data.
+ *
+ * There are two additional restrictions here because we're sharing
+ * hdr -> buf instead of the usual buf -> hdr. First, the hdr can't be
+ * actively involved in an L2ARC write, because if this buf is used by
+ * an arc_write() then the hdr's data buffer will be released when the
+ * write completes, even though the L2ARC write might still be using it.
+ * Second, the hdr's ABD must be linear so that the buf's user doesn't
+ * need to be ABD-aware. It must be allocated via
+ * zio_[data_]buf_alloc(), not as a page, because we need to be able
+ * to abd_release_ownership_of_buf(), which isn't allowed on "linear
+ * page" buffers because the ABD code needs to handle freeing them
+ * specially.
+ */
+ boolean_t can_share = arc_can_share(hdr, buf) &&
+ !HDR_L2_WRITING(hdr) &&
+ hdr->b_l1hdr.b_pabd != NULL &&
+ abd_is_linear(hdr->b_l1hdr.b_pabd) &&
+ !abd_is_linear_page(hdr->b_l1hdr.b_pabd);
+
+ /* Set up b_data and sharing */
+ if (can_share) {
+ buf->b_data = abd_to_buf(hdr->b_l1hdr.b_pabd);
+ buf->b_flags |= ARC_BUF_FLAG_SHARED;
+ arc_hdr_set_flags(hdr, ARC_FLAG_SHARED_DATA);
+ } else {
+ buf->b_data =
+ arc_get_data_buf(hdr, arc_buf_size(buf), buf);
+ ARCSTAT_INCR(arcstat_overhead_size, arc_buf_size(buf));
+ }
+ VERIFY3P(buf->b_data, !=, NULL);
+
+ hdr->b_l1hdr.b_buf = buf;
+ hdr->b_l1hdr.b_bufcnt += 1;
+ if (encrypted)
+ hdr->b_crypt_hdr.b_ebufcnt += 1;
+
+ /*
+ * If the user wants the data from the hdr, we need to either copy or
+ * decompress the data.
+ */
+ if (fill) {
+ ASSERT3P(zb, !=, NULL);
+ return (arc_buf_fill(buf, spa, zb, flags));
+ }
+
+ return (0);
+}
+
+static char *arc_onloan_tag = "onloan";
+
+static inline void
+arc_loaned_bytes_update(int64_t delta)
+{
+ atomic_add_64(&arc_loaned_bytes, delta);
+
+ /* assert that it did not wrap around */
+ ASSERT3S(atomic_add_64_nv(&arc_loaned_bytes, 0), >=, 0);
+}
+
+/*
+ * Loan out an anonymous arc buffer. Loaned buffers are not counted as in
+ * flight data by arc_tempreserve_space() until they are "returned". Loaned
+ * buffers must be returned to the arc before they can be used by the DMU or
+ * freed.
+ */
+arc_buf_t *
+arc_loan_buf(spa_t *spa, boolean_t is_metadata, int size)
+{
+ arc_buf_t *buf = arc_alloc_buf(spa, arc_onloan_tag,
+ is_metadata ? ARC_BUFC_METADATA : ARC_BUFC_DATA, size);
+
+ arc_loaned_bytes_update(arc_buf_size(buf));
+
+ return (buf);
+}
+
+arc_buf_t *
+arc_loan_compressed_buf(spa_t *spa, uint64_t psize, uint64_t lsize,
+ enum zio_compress compression_type, uint8_t complevel)
+{
+ arc_buf_t *buf = arc_alloc_compressed_buf(spa, arc_onloan_tag,
+ psize, lsize, compression_type, complevel);
+
+ arc_loaned_bytes_update(arc_buf_size(buf));
+
+ return (buf);
+}
+
+arc_buf_t *
+arc_loan_raw_buf(spa_t *spa, uint64_t dsobj, boolean_t byteorder,
+ const uint8_t *salt, const uint8_t *iv, const uint8_t *mac,
+ dmu_object_type_t ot, uint64_t psize, uint64_t lsize,
+ enum zio_compress compression_type, uint8_t complevel)
+{
+ arc_buf_t *buf = arc_alloc_raw_buf(spa, arc_onloan_tag, dsobj,
+ byteorder, salt, iv, mac, ot, psize, lsize, compression_type,
+ complevel);
+
+ atomic_add_64(&arc_loaned_bytes, psize);
+ return (buf);
+}
+
+
+/*
+ * Return a loaned arc buffer to the arc.
+ */
+void
+arc_return_buf(arc_buf_t *buf, void *tag)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT3P(buf->b_data, !=, NULL);
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ (void) zfs_refcount_add(&hdr->b_l1hdr.b_refcnt, tag);
+ (void) zfs_refcount_remove(&hdr->b_l1hdr.b_refcnt, arc_onloan_tag);
+
+ arc_loaned_bytes_update(-arc_buf_size(buf));
+}
+
+/* Detach an arc_buf from a dbuf (tag) */
+void
+arc_loan_inuse_buf(arc_buf_t *buf, void *tag)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT3P(buf->b_data, !=, NULL);
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ (void) zfs_refcount_add(&hdr->b_l1hdr.b_refcnt, arc_onloan_tag);
+ (void) zfs_refcount_remove(&hdr->b_l1hdr.b_refcnt, tag);
+
+ arc_loaned_bytes_update(arc_buf_size(buf));
+}
+
+static void
+l2arc_free_abd_on_write(abd_t *abd, size_t size, arc_buf_contents_t type)
+{
+ l2arc_data_free_t *df = kmem_alloc(sizeof (*df), KM_SLEEP);
+
+ df->l2df_abd = abd;
+ df->l2df_size = size;
+ df->l2df_type = type;
+ mutex_enter(&l2arc_free_on_write_mtx);
+ list_insert_head(l2arc_free_on_write, df);
+ mutex_exit(&l2arc_free_on_write_mtx);
+}
+
+static void
+arc_hdr_free_on_write(arc_buf_hdr_t *hdr, boolean_t free_rdata)
+{
+ arc_state_t *state = hdr->b_l1hdr.b_state;
+ arc_buf_contents_t type = arc_buf_type(hdr);
+ uint64_t size = (free_rdata) ? HDR_GET_PSIZE(hdr) : arc_hdr_size(hdr);
+
+ /* protected by hash lock, if in the hash table */
+ if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+ ASSERT(state != arc_anon && state != arc_l2c_only);
+
+ (void) zfs_refcount_remove_many(&state->arcs_esize[type],
+ size, hdr);
+ }
+ (void) zfs_refcount_remove_many(&state->arcs_size, size, hdr);
+ if (type == ARC_BUFC_METADATA) {
+ arc_space_return(size, ARC_SPACE_META);
+ } else {
+ ASSERT(type == ARC_BUFC_DATA);
+ arc_space_return(size, ARC_SPACE_DATA);
+ }
+
+ if (free_rdata) {
+ l2arc_free_abd_on_write(hdr->b_crypt_hdr.b_rabd, size, type);
+ } else {
+ l2arc_free_abd_on_write(hdr->b_l1hdr.b_pabd, size, type);
+ }
+}
+
+/*
+ * Share the arc_buf_t's data with the hdr. Whenever we are sharing the
+ * data buffer, we transfer the refcount ownership to the hdr and update
+ * the appropriate kstats.
+ */
+static void
+arc_share_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
+{
+ ASSERT(arc_can_share(hdr, buf));
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!ARC_BUF_ENCRYPTED(buf));
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+
+ /*
+ * Start sharing the data buffer. We transfer the
+ * refcount ownership to the hdr since it always owns
+ * the refcount whenever an arc_buf_t is shared.
+ */
+ zfs_refcount_transfer_ownership_many(&hdr->b_l1hdr.b_state->arcs_size,
+ arc_hdr_size(hdr), buf, hdr);
+ hdr->b_l1hdr.b_pabd = abd_get_from_buf(buf->b_data, arc_buf_size(buf));
+ abd_take_ownership_of_buf(hdr->b_l1hdr.b_pabd,
+ HDR_ISTYPE_METADATA(hdr));
+ arc_hdr_set_flags(hdr, ARC_FLAG_SHARED_DATA);
+ buf->b_flags |= ARC_BUF_FLAG_SHARED;
+
+ /*
+ * Since we've transferred ownership to the hdr we need
+ * to increment its compressed and uncompressed kstats and
+ * decrement the overhead size.
+ */
+ ARCSTAT_INCR(arcstat_compressed_size, arc_hdr_size(hdr));
+ ARCSTAT_INCR(arcstat_uncompressed_size, HDR_GET_LSIZE(hdr));
+ ARCSTAT_INCR(arcstat_overhead_size, -arc_buf_size(buf));
+}
+
+static void
+arc_unshare_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
+{
+ ASSERT(arc_buf_is_shared(buf));
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+
+ /*
+ * We are no longer sharing this buffer so we need
+ * to transfer its ownership to the rightful owner.
+ */
+ zfs_refcount_transfer_ownership_many(&hdr->b_l1hdr.b_state->arcs_size,
+ arc_hdr_size(hdr), hdr, buf);
+ arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
+ abd_release_ownership_of_buf(hdr->b_l1hdr.b_pabd);
+ abd_put(hdr->b_l1hdr.b_pabd);
+ hdr->b_l1hdr.b_pabd = NULL;
+ buf->b_flags &= ~ARC_BUF_FLAG_SHARED;
+
+ /*
+ * Since the buffer is no longer shared between
+ * the arc buf and the hdr, count it as overhead.
+ */
+ ARCSTAT_INCR(arcstat_compressed_size, -arc_hdr_size(hdr));
+ ARCSTAT_INCR(arcstat_uncompressed_size, -HDR_GET_LSIZE(hdr));
+ ARCSTAT_INCR(arcstat_overhead_size, arc_buf_size(buf));
+}
+
+/*
+ * Remove an arc_buf_t from the hdr's buf list and return the last
+ * arc_buf_t on the list. If no buffers remain on the list then return
+ * NULL.
+ */
+static arc_buf_t *
+arc_buf_remove(arc_buf_hdr_t *hdr, arc_buf_t *buf)
+{
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+
+ arc_buf_t **bufp = &hdr->b_l1hdr.b_buf;
+ arc_buf_t *lastbuf = NULL;
+
+ /*
+ * Remove the buf from the hdr list and locate the last
+ * remaining buffer on the list.
+ */
+ while (*bufp != NULL) {
+ if (*bufp == buf)
+ *bufp = buf->b_next;
+
+ /*
+ * If we've removed a buffer in the middle of
+ * the list then update the lastbuf and update
+ * bufp.
+ */
+ if (*bufp != NULL) {
+ lastbuf = *bufp;
+ bufp = &(*bufp)->b_next;
+ }
+ }
+ buf->b_next = NULL;
+ ASSERT3P(lastbuf, !=, buf);
+ IMPLY(hdr->b_l1hdr.b_bufcnt > 0, lastbuf != NULL);
+ IMPLY(hdr->b_l1hdr.b_bufcnt > 0, hdr->b_l1hdr.b_buf != NULL);
+ IMPLY(lastbuf != NULL, ARC_BUF_LAST(lastbuf));
+
+ return (lastbuf);
+}
+
+/*
+ * Free up buf->b_data and pull the arc_buf_t off of the arc_buf_hdr_t's
+ * list and free it.
+ */
+static void
+arc_buf_destroy_impl(arc_buf_t *buf)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ /*
+ * Free up the data associated with the buf but only if we're not
+ * sharing this with the hdr. If we are sharing it with the hdr, the
+ * hdr is responsible for doing the free.
+ */
+ if (buf->b_data != NULL) {
+ /*
+ * We're about to change the hdr's b_flags. We must either
+ * hold the hash_lock or be undiscoverable.
+ */
+ ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
+
+ arc_cksum_verify(buf);
+ arc_buf_unwatch(buf);
+
+ if (arc_buf_is_shared(buf)) {
+ arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
+ } else {
+ uint64_t size = arc_buf_size(buf);
+ arc_free_data_buf(hdr, buf->b_data, size, buf);
+ ARCSTAT_INCR(arcstat_overhead_size, -size);
+ }
+ buf->b_data = NULL;
+
+ ASSERT(hdr->b_l1hdr.b_bufcnt > 0);
+ hdr->b_l1hdr.b_bufcnt -= 1;
+
+ if (ARC_BUF_ENCRYPTED(buf)) {
+ hdr->b_crypt_hdr.b_ebufcnt -= 1;
+
+ /*
+ * If we have no more encrypted buffers and we've
+ * already gotten a copy of the decrypted data we can
+ * free b_rabd to save some space.
+ */
+ if (hdr->b_crypt_hdr.b_ebufcnt == 0 &&
+ HDR_HAS_RABD(hdr) && hdr->b_l1hdr.b_pabd != NULL &&
+ !HDR_IO_IN_PROGRESS(hdr)) {
+ arc_hdr_free_abd(hdr, B_TRUE);
+ }
+ }
+ }
+
+ arc_buf_t *lastbuf = arc_buf_remove(hdr, buf);
+
+ if (ARC_BUF_SHARED(buf) && !ARC_BUF_COMPRESSED(buf)) {
+ /*
+ * If the current arc_buf_t is sharing its data buffer with the
+ * hdr, then reassign the hdr's b_pabd to share it with the new
+ * buffer at the end of the list. The shared buffer is always
+ * the last one on the hdr's buffer list.
+ *
+ * There is an equivalent case for compressed bufs, but since
+ * they aren't guaranteed to be the last buf in the list and
+ * that is an exceedingly rare case, we just allow that space be
+ * wasted temporarily. We must also be careful not to share
+ * encrypted buffers, since they cannot be shared.
+ */
+ if (lastbuf != NULL && !ARC_BUF_ENCRYPTED(lastbuf)) {
+ /* Only one buf can be shared at once */
+ VERIFY(!arc_buf_is_shared(lastbuf));
+ /* hdr is uncompressed so can't have compressed buf */
+ VERIFY(!ARC_BUF_COMPRESSED(lastbuf));
+
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+ arc_hdr_free_abd(hdr, B_FALSE);
+
+ /*
+ * We must setup a new shared block between the
+ * last buffer and the hdr. The data would have
+ * been allocated by the arc buf so we need to transfer
+ * ownership to the hdr since it's now being shared.
+ */
+ arc_share_buf(hdr, lastbuf);
+ }
+ } else if (HDR_SHARED_DATA(hdr)) {
+ /*
+ * Uncompressed shared buffers are always at the end
+ * of the list. Compressed buffers don't have the
+ * same requirements. This makes it hard to
+ * simply assert that the lastbuf is shared so
+ * we rely on the hdr's compression flags to determine
+ * if we have a compressed, shared buffer.
+ */
+ ASSERT3P(lastbuf, !=, NULL);
+ ASSERT(arc_buf_is_shared(lastbuf) ||
+ arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF);
+ }
+
+ /*
+ * Free the checksum if we're removing the last uncompressed buf from
+ * this hdr.
+ */
+ if (!arc_hdr_has_uncompressed_buf(hdr)) {
+ arc_cksum_free(hdr);
+ }
+
+ /* clean up the buf */
+ buf->b_hdr = NULL;
+ kmem_cache_free(buf_cache, buf);
+}
+
+static void
+arc_hdr_alloc_abd(arc_buf_hdr_t *hdr, int alloc_flags)
+{
+ uint64_t size;
+ boolean_t alloc_rdata = ((alloc_flags & ARC_HDR_ALLOC_RDATA) != 0);
+ boolean_t do_adapt = ((alloc_flags & ARC_HDR_DO_ADAPT) != 0);
+
+ ASSERT3U(HDR_GET_LSIZE(hdr), >, 0);
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT(!HDR_SHARED_DATA(hdr) || alloc_rdata);
+ IMPLY(alloc_rdata, HDR_PROTECTED(hdr));
+
+ if (alloc_rdata) {
+ size = HDR_GET_PSIZE(hdr);
+ ASSERT3P(hdr->b_crypt_hdr.b_rabd, ==, NULL);
+ hdr->b_crypt_hdr.b_rabd = arc_get_data_abd(hdr, size, hdr,
+ do_adapt);
+ ASSERT3P(hdr->b_crypt_hdr.b_rabd, !=, NULL);
+ ARCSTAT_INCR(arcstat_raw_size, size);
+ } else {
+ size = arc_hdr_size(hdr);
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ hdr->b_l1hdr.b_pabd = arc_get_data_abd(hdr, size, hdr,
+ do_adapt);
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+ }
+
+ ARCSTAT_INCR(arcstat_compressed_size, size);
+ ARCSTAT_INCR(arcstat_uncompressed_size, HDR_GET_LSIZE(hdr));
+}
+
+static void
+arc_hdr_free_abd(arc_buf_hdr_t *hdr, boolean_t free_rdata)
+{
+ uint64_t size = (free_rdata) ? HDR_GET_PSIZE(hdr) : arc_hdr_size(hdr);
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT(hdr->b_l1hdr.b_pabd != NULL || HDR_HAS_RABD(hdr));
+ IMPLY(free_rdata, HDR_HAS_RABD(hdr));
+
+ /*
+ * If the hdr is currently being written to the l2arc then
+ * we defer freeing the data by adding it to the l2arc_free_on_write
+ * list. The l2arc will free the data once it's finished
+ * writing it to the l2arc device.
+ */
+ if (HDR_L2_WRITING(hdr)) {
+ arc_hdr_free_on_write(hdr, free_rdata);
+ ARCSTAT_BUMP(arcstat_l2_free_on_write);
+ } else if (free_rdata) {
+ arc_free_data_abd(hdr, hdr->b_crypt_hdr.b_rabd, size, hdr);
+ } else {
+ arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd, size, hdr);
+ }
+
+ if (free_rdata) {
+ hdr->b_crypt_hdr.b_rabd = NULL;
+ ARCSTAT_INCR(arcstat_raw_size, -size);
+ } else {
+ hdr->b_l1hdr.b_pabd = NULL;
+ }
+
+ if (hdr->b_l1hdr.b_pabd == NULL && !HDR_HAS_RABD(hdr))
+ hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
+
+ ARCSTAT_INCR(arcstat_compressed_size, -size);
+ ARCSTAT_INCR(arcstat_uncompressed_size, -HDR_GET_LSIZE(hdr));
+}
+
+static arc_buf_hdr_t *
+arc_hdr_alloc(uint64_t spa, int32_t psize, int32_t lsize,
+ boolean_t protected, enum zio_compress compression_type, uint8_t complevel,
+ arc_buf_contents_t type, boolean_t alloc_rdata)
+{
+ arc_buf_hdr_t *hdr;
+ int flags = ARC_HDR_DO_ADAPT;
+
+ VERIFY(type == ARC_BUFC_DATA || type == ARC_BUFC_METADATA);
+ if (protected) {
+ hdr = kmem_cache_alloc(hdr_full_crypt_cache, KM_PUSHPAGE);
+ } else {
+ hdr = kmem_cache_alloc(hdr_full_cache, KM_PUSHPAGE);
+ }
+ flags |= alloc_rdata ? ARC_HDR_ALLOC_RDATA : 0;
+
+ ASSERT(HDR_EMPTY(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
+ HDR_SET_PSIZE(hdr, psize);
+ HDR_SET_LSIZE(hdr, lsize);
+ hdr->b_spa = spa;
+ hdr->b_type = type;
+ hdr->b_flags = 0;
+ arc_hdr_set_flags(hdr, arc_bufc_to_flags(type) | ARC_FLAG_HAS_L1HDR);
+ arc_hdr_set_compress(hdr, compression_type);
+ hdr->b_complevel = complevel;
+ if (protected)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PROTECTED);
+
+ hdr->b_l1hdr.b_state = arc_anon;
+ hdr->b_l1hdr.b_arc_access = 0;
+ hdr->b_l1hdr.b_bufcnt = 0;
+ hdr->b_l1hdr.b_buf = NULL;
+
+ /*
+ * Allocate the hdr's buffer. This will contain either
+ * the compressed or uncompressed data depending on the block
+ * it references and compressed arc enablement.
+ */
+ arc_hdr_alloc_abd(hdr, flags);
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+
+ return (hdr);
+}
+
+/*
+ * Transition between the two allocation states for the arc_buf_hdr struct.
+ * The arc_buf_hdr struct can be allocated with (hdr_full_cache) or without
+ * (hdr_l2only_cache) the fields necessary for the L1 cache - the smaller
+ * version is used when a cache buffer is only in the L2ARC in order to reduce
+ * memory usage.
+ */
+static arc_buf_hdr_t *
+arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
+{
+ ASSERT(HDR_HAS_L2HDR(hdr));
+
+ arc_buf_hdr_t *nhdr;
+ l2arc_dev_t *dev = hdr->b_l2hdr.b_dev;
+
+ ASSERT((old == hdr_full_cache && new == hdr_l2only_cache) ||
+ (old == hdr_l2only_cache && new == hdr_full_cache));
+
+ /*
+ * if the caller wanted a new full header and the header is to be
+ * encrypted we will actually allocate the header from the full crypt
+ * cache instead. The same applies to freeing from the old cache.
+ */
+ if (HDR_PROTECTED(hdr) && new == hdr_full_cache)
+ new = hdr_full_crypt_cache;
+ if (HDR_PROTECTED(hdr) && old == hdr_full_cache)
+ old = hdr_full_crypt_cache;
+
+ nhdr = kmem_cache_alloc(new, KM_PUSHPAGE);
+
+ ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
+ buf_hash_remove(hdr);
+
+ bcopy(hdr, nhdr, HDR_L2ONLY_SIZE);
+
+ if (new == hdr_full_cache || new == hdr_full_crypt_cache) {
+ arc_hdr_set_flags(nhdr, ARC_FLAG_HAS_L1HDR);
+ /*
+ * arc_access and arc_change_state need to be aware that a
+ * header has just come out of L2ARC, so we set its state to
+ * l2c_only even though it's about to change.
+ */
+ nhdr->b_l1hdr.b_state = arc_l2c_only;
+
+ /* Verify previous threads set to NULL before freeing */
+ ASSERT3P(nhdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ } else {
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ ASSERT0(hdr->b_l1hdr.b_bufcnt);
+ ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
+
+ /*
+ * If we've reached here, We must have been called from
+ * arc_evict_hdr(), as such we should have already been
+ * removed from any ghost list we were previously on
+ * (which protects us from racing with arc_evict_state),
+ * thus no locking is needed during this check.
+ */
+ ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
+
+ /*
+ * A buffer must not be moved into the arc_l2c_only
+ * state if it's not finished being written out to the
+ * l2arc device. Otherwise, the b_l1hdr.b_pabd field
+ * might try to be accessed, even though it was removed.
+ */
+ VERIFY(!HDR_L2_WRITING(hdr));
+ VERIFY3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+
+ arc_hdr_clear_flags(nhdr, ARC_FLAG_HAS_L1HDR);
+ }
+ /*
+ * The header has been reallocated so we need to re-insert it into any
+ * lists it was on.
+ */
+ (void) buf_hash_insert(nhdr, NULL);
+
+ ASSERT(list_link_active(&hdr->b_l2hdr.b_l2node));
+
+ mutex_enter(&dev->l2ad_mtx);
+
+ /*
+ * We must place the realloc'ed header back into the list at
+ * the same spot. Otherwise, if it's placed earlier in the list,
+ * l2arc_write_buffers() could find it during the function's
+ * write phase, and try to write it out to the l2arc.
+ */
+ list_insert_after(&dev->l2ad_buflist, hdr, nhdr);
+ list_remove(&dev->l2ad_buflist, hdr);
+
+ mutex_exit(&dev->l2ad_mtx);
+
+ /*
+ * Since we're using the pointer address as the tag when
+ * incrementing and decrementing the l2ad_alloc refcount, we
+ * must remove the old pointer (that we're about to destroy) and
+ * add the new pointer to the refcount. Otherwise we'd remove
+ * the wrong pointer address when calling arc_hdr_destroy() later.
+ */
+
+ (void) zfs_refcount_remove_many(&dev->l2ad_alloc,
+ arc_hdr_size(hdr), hdr);
+ (void) zfs_refcount_add_many(&dev->l2ad_alloc,
+ arc_hdr_size(nhdr), nhdr);
+
+ buf_discard_identity(hdr);
+ kmem_cache_free(old, hdr);
+
+ return (nhdr);
+}
+
+/*
+ * This function allows an L1 header to be reallocated as a crypt
+ * header and vice versa. If we are going to a crypt header, the
+ * new fields will be zeroed out.
+ */
+static arc_buf_hdr_t *
+arc_hdr_realloc_crypt(arc_buf_hdr_t *hdr, boolean_t need_crypt)
+{
+ arc_buf_hdr_t *nhdr;
+ arc_buf_t *buf;
+ kmem_cache_t *ncache, *ocache;
+ unsigned nsize, osize;
+
+ /*
+ * This function requires that hdr is in the arc_anon state.
+ * Therefore it won't have any L2ARC data for us to worry
+ * about copying.
+ */
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT(!HDR_HAS_L2HDR(hdr));
+ ASSERT3U(!!HDR_PROTECTED(hdr), !=, need_crypt);
+ ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
+ ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
+ ASSERT(!list_link_active(&hdr->b_l2hdr.b_l2node));
+ ASSERT3P(hdr->b_hash_next, ==, NULL);
+
+ if (need_crypt) {
+ ncache = hdr_full_crypt_cache;
+ nsize = sizeof (hdr->b_crypt_hdr);
+ ocache = hdr_full_cache;
+ osize = HDR_FULL_SIZE;
+ } else {
+ ncache = hdr_full_cache;
+ nsize = HDR_FULL_SIZE;
+ ocache = hdr_full_crypt_cache;
+ osize = sizeof (hdr->b_crypt_hdr);
+ }
+
+ nhdr = kmem_cache_alloc(ncache, KM_PUSHPAGE);
+
+ /*
+ * Copy all members that aren't locks or condvars to the new header.
+ * No lists are pointing to us (as we asserted above), so we don't
+ * need to worry about the list nodes.
+ */
+ nhdr->b_dva = hdr->b_dva;
+ nhdr->b_birth = hdr->b_birth;
+ nhdr->b_type = hdr->b_type;
+ nhdr->b_flags = hdr->b_flags;
+ nhdr->b_psize = hdr->b_psize;
+ nhdr->b_lsize = hdr->b_lsize;
+ nhdr->b_spa = hdr->b_spa;
+ nhdr->b_l1hdr.b_freeze_cksum = hdr->b_l1hdr.b_freeze_cksum;
+ nhdr->b_l1hdr.b_bufcnt = hdr->b_l1hdr.b_bufcnt;
+ nhdr->b_l1hdr.b_byteswap = hdr->b_l1hdr.b_byteswap;
+ nhdr->b_l1hdr.b_state = hdr->b_l1hdr.b_state;
+ nhdr->b_l1hdr.b_arc_access = hdr->b_l1hdr.b_arc_access;
+ nhdr->b_l1hdr.b_mru_hits = hdr->b_l1hdr.b_mru_hits;
+ nhdr->b_l1hdr.b_mru_ghost_hits = hdr->b_l1hdr.b_mru_ghost_hits;
+ nhdr->b_l1hdr.b_mfu_hits = hdr->b_l1hdr.b_mfu_hits;
+ nhdr->b_l1hdr.b_mfu_ghost_hits = hdr->b_l1hdr.b_mfu_ghost_hits;
+ nhdr->b_l1hdr.b_l2_hits = hdr->b_l1hdr.b_l2_hits;
+ nhdr->b_l1hdr.b_acb = hdr->b_l1hdr.b_acb;
+ nhdr->b_l1hdr.b_pabd = hdr->b_l1hdr.b_pabd;
+
+ /*
+ * This zfs_refcount_add() exists only to ensure that the individual
+ * arc buffers always point to a header that is referenced, avoiding
+ * a small race condition that could trigger ASSERTs.
+ */
+ (void) zfs_refcount_add(&nhdr->b_l1hdr.b_refcnt, FTAG);
+ nhdr->b_l1hdr.b_buf = hdr->b_l1hdr.b_buf;
+ for (buf = nhdr->b_l1hdr.b_buf; buf != NULL; buf = buf->b_next) {
+ mutex_enter(&buf->b_evict_lock);
+ buf->b_hdr = nhdr;
+ mutex_exit(&buf->b_evict_lock);
+ }
+
+ zfs_refcount_transfer(&nhdr->b_l1hdr.b_refcnt, &hdr->b_l1hdr.b_refcnt);
+ (void) zfs_refcount_remove(&nhdr->b_l1hdr.b_refcnt, FTAG);
+ ASSERT0(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt));
+
+ if (need_crypt) {
+ arc_hdr_set_flags(nhdr, ARC_FLAG_PROTECTED);
+ } else {
+ arc_hdr_clear_flags(nhdr, ARC_FLAG_PROTECTED);
+ }
+
+ /* unset all members of the original hdr */
+ bzero(&hdr->b_dva, sizeof (dva_t));
+ hdr->b_birth = 0;
+ hdr->b_type = ARC_BUFC_INVALID;
+ hdr->b_flags = 0;
+ hdr->b_psize = 0;
+ hdr->b_lsize = 0;
+ hdr->b_spa = 0;
+ hdr->b_l1hdr.b_freeze_cksum = NULL;
+ hdr->b_l1hdr.b_buf = NULL;
+ hdr->b_l1hdr.b_bufcnt = 0;
+ hdr->b_l1hdr.b_byteswap = 0;
+ hdr->b_l1hdr.b_state = NULL;
+ hdr->b_l1hdr.b_arc_access = 0;
+ hdr->b_l1hdr.b_mru_hits = 0;
+ hdr->b_l1hdr.b_mru_ghost_hits = 0;
+ hdr->b_l1hdr.b_mfu_hits = 0;
+ hdr->b_l1hdr.b_mfu_ghost_hits = 0;
+ hdr->b_l1hdr.b_l2_hits = 0;
+ hdr->b_l1hdr.b_acb = NULL;
+ hdr->b_l1hdr.b_pabd = NULL;
+
+ if (ocache == hdr_full_crypt_cache) {
+ ASSERT(!HDR_HAS_RABD(hdr));
+ hdr->b_crypt_hdr.b_ot = DMU_OT_NONE;
+ hdr->b_crypt_hdr.b_ebufcnt = 0;
+ hdr->b_crypt_hdr.b_dsobj = 0;
+ bzero(hdr->b_crypt_hdr.b_salt, ZIO_DATA_SALT_LEN);
+ bzero(hdr->b_crypt_hdr.b_iv, ZIO_DATA_IV_LEN);
+ bzero(hdr->b_crypt_hdr.b_mac, ZIO_DATA_MAC_LEN);
+ }
+
+ buf_discard_identity(hdr);
+ kmem_cache_free(ocache, hdr);
+
+ return (nhdr);
+}
+
+/*
+ * This function is used by the send / receive code to convert a newly
+ * allocated arc_buf_t to one that is suitable for a raw encrypted write. It
+ * is also used to allow the root objset block to be updated without altering
+ * its embedded MACs. Both block types will always be uncompressed so we do not
+ * have to worry about compression type or psize.
+ */
+void
+arc_convert_to_raw(arc_buf_t *buf, uint64_t dsobj, boolean_t byteorder,
+ dmu_object_type_t ot, const uint8_t *salt, const uint8_t *iv,
+ const uint8_t *mac)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT(ot == DMU_OT_DNODE || ot == DMU_OT_OBJSET);
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
+
+ buf->b_flags |= (ARC_BUF_FLAG_COMPRESSED | ARC_BUF_FLAG_ENCRYPTED);
+ if (!HDR_PROTECTED(hdr))
+ hdr = arc_hdr_realloc_crypt(hdr, B_TRUE);
+ hdr->b_crypt_hdr.b_dsobj = dsobj;
+ hdr->b_crypt_hdr.b_ot = ot;
+ hdr->b_l1hdr.b_byteswap = (byteorder == ZFS_HOST_BYTEORDER) ?
+ DMU_BSWAP_NUMFUNCS : DMU_OT_BYTESWAP(ot);
+ if (!arc_hdr_has_uncompressed_buf(hdr))
+ arc_cksum_free(hdr);
+
+ if (salt != NULL)
+ bcopy(salt, hdr->b_crypt_hdr.b_salt, ZIO_DATA_SALT_LEN);
+ if (iv != NULL)
+ bcopy(iv, hdr->b_crypt_hdr.b_iv, ZIO_DATA_IV_LEN);
+ if (mac != NULL)
+ bcopy(mac, hdr->b_crypt_hdr.b_mac, ZIO_DATA_MAC_LEN);
+}
+
+/*
+ * Allocate a new arc_buf_hdr_t and arc_buf_t and return the buf to the caller.
+ * The buf is returned thawed since we expect the consumer to modify it.
+ */
+arc_buf_t *
+arc_alloc_buf(spa_t *spa, void *tag, arc_buf_contents_t type, int32_t size)
+{
+ arc_buf_hdr_t *hdr = arc_hdr_alloc(spa_load_guid(spa), size, size,
+ B_FALSE, ZIO_COMPRESS_OFF, 0, type, B_FALSE);
+
+ arc_buf_t *buf = NULL;
+ VERIFY0(arc_buf_alloc_impl(hdr, spa, NULL, tag, B_FALSE, B_FALSE,
+ B_FALSE, B_FALSE, &buf));
+ arc_buf_thaw(buf);
+
+ return (buf);
+}
+
+/*
+ * Allocate a compressed buf in the same manner as arc_alloc_buf. Don't use this
+ * for bufs containing metadata.
+ */
+arc_buf_t *
+arc_alloc_compressed_buf(spa_t *spa, void *tag, uint64_t psize, uint64_t lsize,
+ enum zio_compress compression_type, uint8_t complevel)
+{
+ ASSERT3U(lsize, >, 0);
+ ASSERT3U(lsize, >=, psize);
+ ASSERT3U(compression_type, >, ZIO_COMPRESS_OFF);
+ ASSERT3U(compression_type, <, ZIO_COMPRESS_FUNCTIONS);
+
+ arc_buf_hdr_t *hdr = arc_hdr_alloc(spa_load_guid(spa), psize, lsize,
+ B_FALSE, compression_type, complevel, ARC_BUFC_DATA, B_FALSE);
+
+ arc_buf_t *buf = NULL;
+ VERIFY0(arc_buf_alloc_impl(hdr, spa, NULL, tag, B_FALSE,
+ B_TRUE, B_FALSE, B_FALSE, &buf));
+ arc_buf_thaw(buf);
+ ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
+
+ if (!arc_buf_is_shared(buf)) {
+ /*
+ * To ensure that the hdr has the correct data in it if we call
+ * arc_untransform() on this buf before it's been written to
+ * disk, it's easiest if we just set up sharing between the
+ * buf and the hdr.
+ */
+ arc_hdr_free_abd(hdr, B_FALSE);
+ arc_share_buf(hdr, buf);
+ }
+
+ return (buf);
+}
+
+arc_buf_t *
+arc_alloc_raw_buf(spa_t *spa, void *tag, uint64_t dsobj, boolean_t byteorder,
+ const uint8_t *salt, const uint8_t *iv, const uint8_t *mac,
+ dmu_object_type_t ot, uint64_t psize, uint64_t lsize,
+ enum zio_compress compression_type, uint8_t complevel)
+{
+ arc_buf_hdr_t *hdr;
+ arc_buf_t *buf;
+ arc_buf_contents_t type = DMU_OT_IS_METADATA(ot) ?
+ ARC_BUFC_METADATA : ARC_BUFC_DATA;
+
+ ASSERT3U(lsize, >, 0);
+ ASSERT3U(lsize, >=, psize);
+ ASSERT3U(compression_type, >=, ZIO_COMPRESS_OFF);
+ ASSERT3U(compression_type, <, ZIO_COMPRESS_FUNCTIONS);
+
+ hdr = arc_hdr_alloc(spa_load_guid(spa), psize, lsize, B_TRUE,
+ compression_type, complevel, type, B_TRUE);
+
+ hdr->b_crypt_hdr.b_dsobj = dsobj;
+ hdr->b_crypt_hdr.b_ot = ot;
+ hdr->b_l1hdr.b_byteswap = (byteorder == ZFS_HOST_BYTEORDER) ?
+ DMU_BSWAP_NUMFUNCS : DMU_OT_BYTESWAP(ot);
+ bcopy(salt, hdr->b_crypt_hdr.b_salt, ZIO_DATA_SALT_LEN);
+ bcopy(iv, hdr->b_crypt_hdr.b_iv, ZIO_DATA_IV_LEN);
+ bcopy(mac, hdr->b_crypt_hdr.b_mac, ZIO_DATA_MAC_LEN);
+
+ /*
+ * This buffer will be considered encrypted even if the ot is not an
+ * encrypted type. It will become authenticated instead in
+ * arc_write_ready().
+ */
+ buf = NULL;
+ VERIFY0(arc_buf_alloc_impl(hdr, spa, NULL, tag, B_TRUE, B_TRUE,
+ B_FALSE, B_FALSE, &buf));
+ arc_buf_thaw(buf);
+ ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
+
+ return (buf);
+}
+
+static void
+arc_hdr_l2hdr_destroy(arc_buf_hdr_t *hdr)
+{
+ l2arc_buf_hdr_t *l2hdr = &hdr->b_l2hdr;
+ l2arc_dev_t *dev = l2hdr->b_dev;
+ uint64_t psize = HDR_GET_PSIZE(hdr);
+ uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev, psize);
+
+ ASSERT(MUTEX_HELD(&dev->l2ad_mtx));
+ ASSERT(HDR_HAS_L2HDR(hdr));
+
+ list_remove(&dev->l2ad_buflist, hdr);
+
+ ARCSTAT_INCR(arcstat_l2_psize, -psize);
+ ARCSTAT_INCR(arcstat_l2_lsize, -HDR_GET_LSIZE(hdr));
+
+ vdev_space_update(dev->l2ad_vdev, -asize, 0, 0);
+
+ (void) zfs_refcount_remove_many(&dev->l2ad_alloc, arc_hdr_size(hdr),
+ hdr);
+ arc_hdr_clear_flags(hdr, ARC_FLAG_HAS_L2HDR);
+}
+
+static void
+arc_hdr_destroy(arc_buf_hdr_t *hdr)
+{
+ if (HDR_HAS_L1HDR(hdr)) {
+ ASSERT(hdr->b_l1hdr.b_buf == NULL ||
+ hdr->b_l1hdr.b_bufcnt > 0);
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+ ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
+ }
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ ASSERT(!HDR_IN_HASH_TABLE(hdr));
+
+ if (HDR_HAS_L2HDR(hdr)) {
+ l2arc_dev_t *dev = hdr->b_l2hdr.b_dev;
+ boolean_t buflist_held = MUTEX_HELD(&dev->l2ad_mtx);
+
+ if (!buflist_held)
+ mutex_enter(&dev->l2ad_mtx);
+
+ /*
+ * Even though we checked this conditional above, we
+ * need to check this again now that we have the
+ * l2ad_mtx. This is because we could be racing with
+ * another thread calling l2arc_evict() which might have
+ * destroyed this header's L2 portion as we were waiting
+ * to acquire the l2ad_mtx. If that happens, we don't
+ * want to re-destroy the header's L2 portion.
+ */
+ if (HDR_HAS_L2HDR(hdr))
+ arc_hdr_l2hdr_destroy(hdr);
+
+ if (!buflist_held)
+ mutex_exit(&dev->l2ad_mtx);
+ }
+
+ /*
+ * The header's identify can only be safely discarded once it is no
+ * longer discoverable. This requires removing it from the hash table
+ * and the l2arc header list. After this point the hash lock can not
+ * be used to protect the header.
+ */
+ if (!HDR_EMPTY(hdr))
+ buf_discard_identity(hdr);
+
+ if (HDR_HAS_L1HDR(hdr)) {
+ arc_cksum_free(hdr);
+
+ while (hdr->b_l1hdr.b_buf != NULL)
+ arc_buf_destroy_impl(hdr->b_l1hdr.b_buf);
+
+ if (hdr->b_l1hdr.b_pabd != NULL)
+ arc_hdr_free_abd(hdr, B_FALSE);
+
+ if (HDR_HAS_RABD(hdr))
+ arc_hdr_free_abd(hdr, B_TRUE);
+ }
+
+ ASSERT3P(hdr->b_hash_next, ==, NULL);
+ if (HDR_HAS_L1HDR(hdr)) {
+ ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
+ ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
+
+ if (!HDR_PROTECTED(hdr)) {
+ kmem_cache_free(hdr_full_cache, hdr);
+ } else {
+ kmem_cache_free(hdr_full_crypt_cache, hdr);
+ }
+ } else {
+ kmem_cache_free(hdr_l2only_cache, hdr);
+ }
+}
+
+void
+arc_buf_destroy(arc_buf_t *buf, void* tag)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ if (hdr->b_l1hdr.b_state == arc_anon) {
+ ASSERT3U(hdr->b_l1hdr.b_bufcnt, ==, 1);
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ VERIFY0(remove_reference(hdr, NULL, tag));
+ arc_hdr_destroy(hdr);
+ return;
+ }
+
+ kmutex_t *hash_lock = HDR_LOCK(hdr);
+ mutex_enter(hash_lock);
+
+ ASSERT3P(hdr, ==, buf->b_hdr);
+ ASSERT(hdr->b_l1hdr.b_bufcnt > 0);
+ ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_state, !=, arc_anon);
+ ASSERT3P(buf->b_data, !=, NULL);
+
+ (void) remove_reference(hdr, hash_lock, tag);
+ arc_buf_destroy_impl(buf);
+ mutex_exit(hash_lock);
+}
+
+/*
+ * Evict the arc_buf_hdr that is provided as a parameter. The resultant
+ * state of the header is dependent on its state prior to entering this
+ * function. The following transitions are possible:
+ *
+ * - arc_mru -> arc_mru_ghost
+ * - arc_mfu -> arc_mfu_ghost
+ * - arc_mru_ghost -> arc_l2c_only
+ * - arc_mru_ghost -> deleted
+ * - arc_mfu_ghost -> arc_l2c_only
+ * - arc_mfu_ghost -> deleted
+ */
+static int64_t
+arc_evict_hdr(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
+{
+ arc_state_t *evicted_state, *state;
+ int64_t bytes_evicted = 0;
+ int min_lifetime = HDR_PRESCIENT_PREFETCH(hdr) ?
+ arc_min_prescient_prefetch_ms : arc_min_prefetch_ms;
+
+ ASSERT(MUTEX_HELD(hash_lock));
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ state = hdr->b_l1hdr.b_state;
+ if (GHOST_STATE(state)) {
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+
+ /*
+ * l2arc_write_buffers() relies on a header's L1 portion
+ * (i.e. its b_pabd field) during it's write phase.
+ * Thus, we cannot push a header onto the arc_l2c_only
+ * state (removing its L1 piece) until the header is
+ * done being written to the l2arc.
+ */
+ if (HDR_HAS_L2HDR(hdr) && HDR_L2_WRITING(hdr)) {
+ ARCSTAT_BUMP(arcstat_evict_l2_skip);
+ return (bytes_evicted);
+ }
+
+ ARCSTAT_BUMP(arcstat_deleted);
+ bytes_evicted += HDR_GET_LSIZE(hdr);
+
+ DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, hdr);
+
+ if (HDR_HAS_L2HDR(hdr)) {
+ ASSERT(hdr->b_l1hdr.b_pabd == NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ /*
+ * This buffer is cached on the 2nd Level ARC;
+ * don't destroy the header.
+ */
+ arc_change_state(arc_l2c_only, hdr, hash_lock);
+ /*
+ * dropping from L1+L2 cached to L2-only,
+ * realloc to remove the L1 header.
+ */
+ hdr = arc_hdr_realloc(hdr, hdr_full_cache,
+ hdr_l2only_cache);
+ } else {
+ arc_change_state(arc_anon, hdr, hash_lock);
+ arc_hdr_destroy(hdr);
+ }
+ return (bytes_evicted);
+ }
+
+ ASSERT(state == arc_mru || state == arc_mfu);
+ evicted_state = (state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost;
+
+ /* prefetch buffers have a minimum lifespan */
+ if (HDR_IO_IN_PROGRESS(hdr) ||
+ ((hdr->b_flags & (ARC_FLAG_PREFETCH | ARC_FLAG_INDIRECT)) &&
+ ddi_get_lbolt() - hdr->b_l1hdr.b_arc_access <
+ MSEC_TO_TICK(min_lifetime))) {
+ ARCSTAT_BUMP(arcstat_evict_skip);
+ return (bytes_evicted);
+ }
+
+ ASSERT0(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt));
+ while (hdr->b_l1hdr.b_buf) {
+ arc_buf_t *buf = hdr->b_l1hdr.b_buf;
+ if (!mutex_tryenter(&buf->b_evict_lock)) {
+ ARCSTAT_BUMP(arcstat_mutex_miss);
+ break;
+ }
+ if (buf->b_data != NULL)
+ bytes_evicted += HDR_GET_LSIZE(hdr);
+ mutex_exit(&buf->b_evict_lock);
+ arc_buf_destroy_impl(buf);
+ }
+
+ if (HDR_HAS_L2HDR(hdr)) {
+ ARCSTAT_INCR(arcstat_evict_l2_cached, HDR_GET_LSIZE(hdr));
+ } else {
+ if (l2arc_write_eligible(hdr->b_spa, hdr)) {
+ ARCSTAT_INCR(arcstat_evict_l2_eligible,
+ HDR_GET_LSIZE(hdr));
+ } else {
+ ARCSTAT_INCR(arcstat_evict_l2_ineligible,
+ HDR_GET_LSIZE(hdr));
+ }
+ }
+
+ if (hdr->b_l1hdr.b_bufcnt == 0) {
+ arc_cksum_free(hdr);
+
+ bytes_evicted += arc_hdr_size(hdr);
+
+ /*
+ * If this hdr is being evicted and has a compressed
+ * buffer then we discard it here before we change states.
+ * This ensures that the accounting is updated correctly
+ * in arc_free_data_impl().
+ */
+ if (hdr->b_l1hdr.b_pabd != NULL)
+ arc_hdr_free_abd(hdr, B_FALSE);
+
+ if (HDR_HAS_RABD(hdr))
+ arc_hdr_free_abd(hdr, B_TRUE);
+
+ arc_change_state(evicted_state, hdr, hash_lock);
+ ASSERT(HDR_IN_HASH_TABLE(hdr));
+ arc_hdr_set_flags(hdr, ARC_FLAG_IN_HASH_TABLE);
+ DTRACE_PROBE1(arc__evict, arc_buf_hdr_t *, hdr);
+ }
+
+ return (bytes_evicted);
+}
+
+static void
+arc_set_need_free(void)
+{
+ ASSERT(MUTEX_HELD(&arc_evict_lock));
+ int64_t remaining = arc_free_memory() - arc_sys_free / 2;
+ arc_evict_waiter_t *aw = list_tail(&arc_evict_waiters);
+ if (aw == NULL) {
+ arc_need_free = MAX(-remaining, 0);
+ } else {
+ arc_need_free =
+ MAX(-remaining, (int64_t)(aw->aew_count - arc_evict_count));
+ }
+}
+
+static uint64_t
+arc_evict_state_impl(multilist_t *ml, int idx, arc_buf_hdr_t *marker,
+ uint64_t spa, int64_t bytes)
+{
+ multilist_sublist_t *mls;
+ uint64_t bytes_evicted = 0;
+ arc_buf_hdr_t *hdr;
+ kmutex_t *hash_lock;
+ int evict_count = 0;
+
+ ASSERT3P(marker, !=, NULL);
+ IMPLY(bytes < 0, bytes == ARC_EVICT_ALL);
+
+ mls = multilist_sublist_lock(ml, idx);
+
+ for (hdr = multilist_sublist_prev(mls, marker); hdr != NULL;
+ hdr = multilist_sublist_prev(mls, marker)) {
+ if ((bytes != ARC_EVICT_ALL && bytes_evicted >= bytes) ||
+ (evict_count >= zfs_arc_evict_batch_limit))
+ break;
+
+ /*
+ * To keep our iteration location, move the marker
+ * forward. Since we're not holding hdr's hash lock, we
+ * must be very careful and not remove 'hdr' from the
+ * sublist. Otherwise, other consumers might mistake the
+ * 'hdr' as not being on a sublist when they call the
+ * multilist_link_active() function (they all rely on
+ * the hash lock protecting concurrent insertions and
+ * removals). multilist_sublist_move_forward() was
+ * specifically implemented to ensure this is the case
+ * (only 'marker' will be removed and re-inserted).
+ */
+ multilist_sublist_move_forward(mls, marker);
+
+ /*
+ * The only case where the b_spa field should ever be
+ * zero, is the marker headers inserted by
+ * arc_evict_state(). It's possible for multiple threads
+ * to be calling arc_evict_state() concurrently (e.g.
+ * dsl_pool_close() and zio_inject_fault()), so we must
+ * skip any markers we see from these other threads.
+ */
+ if (hdr->b_spa == 0)
+ continue;
+
+ /* we're only interested in evicting buffers of a certain spa */
+ if (spa != 0 && hdr->b_spa != spa) {
+ ARCSTAT_BUMP(arcstat_evict_skip);
+ continue;
+ }
+
+ hash_lock = HDR_LOCK(hdr);
+
+ /*
+ * We aren't calling this function from any code path
+ * that would already be holding a hash lock, so we're
+ * asserting on this assumption to be defensive in case
+ * this ever changes. Without this check, it would be
+ * possible to incorrectly increment arcstat_mutex_miss
+ * below (e.g. if the code changed such that we called
+ * this function with a hash lock held).
+ */
+ ASSERT(!MUTEX_HELD(hash_lock));
+
+ if (mutex_tryenter(hash_lock)) {
+ uint64_t evicted = arc_evict_hdr(hdr, hash_lock);
+ mutex_exit(hash_lock);
+
+ bytes_evicted += evicted;
+
+ /*
+ * If evicted is zero, arc_evict_hdr() must have
+ * decided to skip this header, don't increment
+ * evict_count in this case.
+ */
+ if (evicted != 0)
+ evict_count++;
+
+ } else {
+ ARCSTAT_BUMP(arcstat_mutex_miss);
+ }
+ }
+
+ multilist_sublist_unlock(mls);
+
+ /*
+ * Increment the count of evicted bytes, and wake up any threads that
+ * are waiting for the count to reach this value. Since the list is
+ * ordered by ascending aew_count, we pop off the beginning of the
+ * list until we reach the end, or a waiter that's past the current
+ * "count". Doing this outside the loop reduces the number of times
+ * we need to acquire the global arc_evict_lock.
+ *
+ * Only wake when there's sufficient free memory in the system
+ * (specifically, arc_sys_free/2, which by default is a bit more than
+ * 1/64th of RAM). See the comments in arc_wait_for_eviction().
+ */
+ mutex_enter(&arc_evict_lock);
+ arc_evict_count += bytes_evicted;
+
+ if ((int64_t)(arc_free_memory() - arc_sys_free / 2) > 0) {
+ arc_evict_waiter_t *aw;
+ while ((aw = list_head(&arc_evict_waiters)) != NULL &&
+ aw->aew_count <= arc_evict_count) {
+ list_remove(&arc_evict_waiters, aw);
+ cv_broadcast(&aw->aew_cv);
+ }
+ }
+ arc_set_need_free();
+ mutex_exit(&arc_evict_lock);
+
+ /*
+ * If the ARC size is reduced from arc_c_max to arc_c_min (especially
+ * if the average cached block is small), eviction can be on-CPU for
+ * many seconds. To ensure that other threads that may be bound to
+ * this CPU are able to make progress, make a voluntary preemption
+ * call here.
+ */
+ cond_resched();
+
+ return (bytes_evicted);
+}
+
+/*
+ * Evict buffers from the given arc state, until we've removed the
+ * specified number of bytes. Move the removed buffers to the
+ * appropriate evict state.
+ *
+ * This function makes a "best effort". It skips over any buffers
+ * it can't get a hash_lock on, and so, may not catch all candidates.
+ * It may also return without evicting as much space as requested.
+ *
+ * If bytes is specified using the special value ARC_EVICT_ALL, this
+ * will evict all available (i.e. unlocked and evictable) buffers from
+ * the given arc state; which is used by arc_flush().
+ */
+static uint64_t
+arc_evict_state(arc_state_t *state, uint64_t spa, int64_t bytes,
+ arc_buf_contents_t type)
+{
+ uint64_t total_evicted = 0;
+ multilist_t *ml = state->arcs_list[type];
+ int num_sublists;
+ arc_buf_hdr_t **markers;
+
+ IMPLY(bytes < 0, bytes == ARC_EVICT_ALL);
+
+ num_sublists = multilist_get_num_sublists(ml);
+
+ /*
+ * If we've tried to evict from each sublist, made some
+ * progress, but still have not hit the target number of bytes
+ * to evict, we want to keep trying. The markers allow us to
+ * pick up where we left off for each individual sublist, rather
+ * than starting from the tail each time.
+ */
+ markers = kmem_zalloc(sizeof (*markers) * num_sublists, KM_SLEEP);
+ for (int i = 0; i < num_sublists; i++) {
+ multilist_sublist_t *mls;
+
+ markers[i] = kmem_cache_alloc(hdr_full_cache, KM_SLEEP);
+
+ /*
+ * A b_spa of 0 is used to indicate that this header is
+ * a marker. This fact is used in arc_evict_type() and
+ * arc_evict_state_impl().
+ */
+ markers[i]->b_spa = 0;
+
+ mls = multilist_sublist_lock(ml, i);
+ multilist_sublist_insert_tail(mls, markers[i]);
+ multilist_sublist_unlock(mls);
+ }
+
+ /*
+ * While we haven't hit our target number of bytes to evict, or
+ * we're evicting all available buffers.
+ */
+ while (total_evicted < bytes || bytes == ARC_EVICT_ALL) {
+ int sublist_idx = multilist_get_random_index(ml);
+ uint64_t scan_evicted = 0;
+
+ /*
+ * Try to reduce pinned dnodes with a floor of arc_dnode_limit.
+ * Request that 10% of the LRUs be scanned by the superblock
+ * shrinker.
+ */
+ if (type == ARC_BUFC_DATA && aggsum_compare(&astat_dnode_size,
+ arc_dnode_size_limit) > 0) {
+ arc_prune_async((aggsum_upper_bound(&astat_dnode_size) -
+ arc_dnode_size_limit) / sizeof (dnode_t) /
+ zfs_arc_dnode_reduce_percent);
+ }
+
+ /*
+ * Start eviction using a randomly selected sublist,
+ * this is to try and evenly balance eviction across all
+ * sublists. Always starting at the same sublist
+ * (e.g. index 0) would cause evictions to favor certain
+ * sublists over others.
+ */
+ for (int i = 0; i < num_sublists; i++) {
+ uint64_t bytes_remaining;
+ uint64_t bytes_evicted;
+
+ if (bytes == ARC_EVICT_ALL)
+ bytes_remaining = ARC_EVICT_ALL;
+ else if (total_evicted < bytes)
+ bytes_remaining = bytes - total_evicted;
+ else
+ break;
+
+ bytes_evicted = arc_evict_state_impl(ml, sublist_idx,
+ markers[sublist_idx], spa, bytes_remaining);
+
+ scan_evicted += bytes_evicted;
+ total_evicted += bytes_evicted;
+
+ /* we've reached the end, wrap to the beginning */
+ if (++sublist_idx >= num_sublists)
+ sublist_idx = 0;
+ }
+
+ /*
+ * If we didn't evict anything during this scan, we have
+ * no reason to believe we'll evict more during another
+ * scan, so break the loop.
+ */
+ if (scan_evicted == 0) {
+ /* This isn't possible, let's make that obvious */
+ ASSERT3S(bytes, !=, 0);
+
+ /*
+ * When bytes is ARC_EVICT_ALL, the only way to
+ * break the loop is when scan_evicted is zero.
+ * In that case, we actually have evicted enough,
+ * so we don't want to increment the kstat.
+ */
+ if (bytes != ARC_EVICT_ALL) {
+ ASSERT3S(total_evicted, <, bytes);
+ ARCSTAT_BUMP(arcstat_evict_not_enough);
+ }
+
+ break;
+ }
+ }
+
+ for (int i = 0; i < num_sublists; i++) {
+ multilist_sublist_t *mls = multilist_sublist_lock(ml, i);
+ multilist_sublist_remove(mls, markers[i]);
+ multilist_sublist_unlock(mls);
+
+ kmem_cache_free(hdr_full_cache, markers[i]);
+ }
+ kmem_free(markers, sizeof (*markers) * num_sublists);
+
+ return (total_evicted);
+}
+
+/*
+ * Flush all "evictable" data of the given type from the arc state
+ * specified. This will not evict any "active" buffers (i.e. referenced).
+ *
+ * When 'retry' is set to B_FALSE, the function will make a single pass
+ * over the state and evict any buffers that it can. Since it doesn't
+ * continually retry the eviction, it might end up leaving some buffers
+ * in the ARC due to lock misses.
+ *
+ * When 'retry' is set to B_TRUE, the function will continually retry the
+ * eviction until *all* evictable buffers have been removed from the
+ * state. As a result, if concurrent insertions into the state are
+ * allowed (e.g. if the ARC isn't shutting down), this function might
+ * wind up in an infinite loop, continually trying to evict buffers.
+ */
+static uint64_t
+arc_flush_state(arc_state_t *state, uint64_t spa, arc_buf_contents_t type,
+ boolean_t retry)
+{
+ uint64_t evicted = 0;
+
+ while (zfs_refcount_count(&state->arcs_esize[type]) != 0) {
+ evicted += arc_evict_state(state, spa, ARC_EVICT_ALL, type);
+
+ if (!retry)
+ break;
+ }
+
+ return (evicted);
+}
+
+/*
+ * Evict the specified number of bytes from the state specified,
+ * restricting eviction to the spa and type given. This function
+ * prevents us from trying to evict more from a state's list than
+ * is "evictable", and to skip evicting altogether when passed a
+ * negative value for "bytes". In contrast, arc_evict_state() will
+ * evict everything it can, when passed a negative value for "bytes".
+ */
+static uint64_t
+arc_evict_impl(arc_state_t *state, uint64_t spa, int64_t bytes,
+ arc_buf_contents_t type)
+{
+ int64_t delta;
+
+ if (bytes > 0 && zfs_refcount_count(&state->arcs_esize[type]) > 0) {
+ delta = MIN(zfs_refcount_count(&state->arcs_esize[type]),
+ bytes);
+ return (arc_evict_state(state, spa, delta, type));
+ }
+
+ return (0);
+}
+
+/*
+ * The goal of this function is to evict enough meta data buffers from the
+ * ARC in order to enforce the arc_meta_limit. Achieving this is slightly
+ * more complicated than it appears because it is common for data buffers
+ * to have holds on meta data buffers. In addition, dnode meta data buffers
+ * will be held by the dnodes in the block preventing them from being freed.
+ * This means we can't simply traverse the ARC and expect to always find
+ * enough unheld meta data buffer to release.
+ *
+ * Therefore, this function has been updated to make alternating passes
+ * over the ARC releasing data buffers and then newly unheld meta data
+ * buffers. This ensures forward progress is maintained and meta_used
+ * will decrease. Normally this is sufficient, but if required the ARC
+ * will call the registered prune callbacks causing dentry and inodes to
+ * be dropped from the VFS cache. This will make dnode meta data buffers
+ * available for reclaim.
+ */
+static uint64_t
+arc_evict_meta_balanced(uint64_t meta_used)
+{
+ int64_t delta, prune = 0, adjustmnt;
+ uint64_t total_evicted = 0;
+ arc_buf_contents_t type = ARC_BUFC_DATA;
+ int restarts = MAX(zfs_arc_meta_adjust_restarts, 0);
+
+restart:
+ /*
+ * This slightly differs than the way we evict from the mru in
+ * arc_evict because we don't have a "target" value (i.e. no
+ * "meta" arc_p). As a result, I think we can completely
+ * cannibalize the metadata in the MRU before we evict the
+ * metadata from the MFU. I think we probably need to implement a
+ * "metadata arc_p" value to do this properly.
+ */
+ adjustmnt = meta_used - arc_meta_limit;
+
+ if (adjustmnt > 0 &&
+ zfs_refcount_count(&arc_mru->arcs_esize[type]) > 0) {
+ delta = MIN(zfs_refcount_count(&arc_mru->arcs_esize[type]),
+ adjustmnt);
+ total_evicted += arc_evict_impl(arc_mru, 0, delta, type);
+ adjustmnt -= delta;
+ }
+
+ /*
+ * We can't afford to recalculate adjustmnt here. If we do,
+ * new metadata buffers can sneak into the MRU or ANON lists,
+ * thus penalize the MFU metadata. Although the fudge factor is
+ * small, it has been empirically shown to be significant for
+ * certain workloads (e.g. creating many empty directories). As
+ * such, we use the original calculation for adjustmnt, and
+ * simply decrement the amount of data evicted from the MRU.
+ */
+
+ if (adjustmnt > 0 &&
+ zfs_refcount_count(&arc_mfu->arcs_esize[type]) > 0) {
+ delta = MIN(zfs_refcount_count(&arc_mfu->arcs_esize[type]),
+ adjustmnt);
+ total_evicted += arc_evict_impl(arc_mfu, 0, delta, type);
+ }
+
+ adjustmnt = meta_used - arc_meta_limit;
+
+ if (adjustmnt > 0 &&
+ zfs_refcount_count(&arc_mru_ghost->arcs_esize[type]) > 0) {
+ delta = MIN(adjustmnt,
+ zfs_refcount_count(&arc_mru_ghost->arcs_esize[type]));
+ total_evicted += arc_evict_impl(arc_mru_ghost, 0, delta, type);
+ adjustmnt -= delta;
+ }
+
+ if (adjustmnt > 0 &&
+ zfs_refcount_count(&arc_mfu_ghost->arcs_esize[type]) > 0) {
+ delta = MIN(adjustmnt,
+ zfs_refcount_count(&arc_mfu_ghost->arcs_esize[type]));
+ total_evicted += arc_evict_impl(arc_mfu_ghost, 0, delta, type);
+ }
+
+ /*
+ * If after attempting to make the requested adjustment to the ARC
+ * the meta limit is still being exceeded then request that the
+ * higher layers drop some cached objects which have holds on ARC
+ * meta buffers. Requests to the upper layers will be made with
+ * increasingly large scan sizes until the ARC is below the limit.
+ */
+ if (meta_used > arc_meta_limit) {
+ if (type == ARC_BUFC_DATA) {
+ type = ARC_BUFC_METADATA;
+ } else {
+ type = ARC_BUFC_DATA;
+
+ if (zfs_arc_meta_prune) {
+ prune += zfs_arc_meta_prune;
+ arc_prune_async(prune);
+ }
+ }
+
+ if (restarts > 0) {
+ restarts--;
+ goto restart;
+ }
+ }
+ return (total_evicted);
+}
+
+/*
+ * Evict metadata buffers from the cache, such that arc_meta_used is
+ * capped by the arc_meta_limit tunable.
+ */
+static uint64_t
+arc_evict_meta_only(uint64_t meta_used)
+{
+ uint64_t total_evicted = 0;
+ int64_t target;
+
+ /*
+ * If we're over the meta limit, we want to evict enough
+ * metadata to get back under the meta limit. We don't want to
+ * evict so much that we drop the MRU below arc_p, though. If
+ * we're over the meta limit more than we're over arc_p, we
+ * evict some from the MRU here, and some from the MFU below.
+ */
+ target = MIN((int64_t)(meta_used - arc_meta_limit),
+ (int64_t)(zfs_refcount_count(&arc_anon->arcs_size) +
+ zfs_refcount_count(&arc_mru->arcs_size) - arc_p));
+
+ total_evicted += arc_evict_impl(arc_mru, 0, target, ARC_BUFC_METADATA);
+
+ /*
+ * Similar to the above, we want to evict enough bytes to get us
+ * below the meta limit, but not so much as to drop us below the
+ * space allotted to the MFU (which is defined as arc_c - arc_p).
+ */
+ target = MIN((int64_t)(meta_used - arc_meta_limit),
+ (int64_t)(zfs_refcount_count(&arc_mfu->arcs_size) -
+ (arc_c - arc_p)));
+
+ total_evicted += arc_evict_impl(arc_mfu, 0, target, ARC_BUFC_METADATA);
+
+ return (total_evicted);
+}
+
+static uint64_t
+arc_evict_meta(uint64_t meta_used)
+{
+ if (zfs_arc_meta_strategy == ARC_STRATEGY_META_ONLY)
+ return (arc_evict_meta_only(meta_used));
+ else
+ return (arc_evict_meta_balanced(meta_used));
+}
+
+/*
+ * Return the type of the oldest buffer in the given arc state
+ *
+ * This function will select a random sublist of type ARC_BUFC_DATA and
+ * a random sublist of type ARC_BUFC_METADATA. The tail of each sublist
+ * is compared, and the type which contains the "older" buffer will be
+ * returned.
+ */
+static arc_buf_contents_t
+arc_evict_type(arc_state_t *state)
+{
+ multilist_t *data_ml = state->arcs_list[ARC_BUFC_DATA];
+ multilist_t *meta_ml = state->arcs_list[ARC_BUFC_METADATA];
+ int data_idx = multilist_get_random_index(data_ml);
+ int meta_idx = multilist_get_random_index(meta_ml);
+ multilist_sublist_t *data_mls;
+ multilist_sublist_t *meta_mls;
+ arc_buf_contents_t type;
+ arc_buf_hdr_t *data_hdr;
+ arc_buf_hdr_t *meta_hdr;
+
+ /*
+ * We keep the sublist lock until we're finished, to prevent
+ * the headers from being destroyed via arc_evict_state().
+ */
+ data_mls = multilist_sublist_lock(data_ml, data_idx);
+ meta_mls = multilist_sublist_lock(meta_ml, meta_idx);
+
+ /*
+ * These two loops are to ensure we skip any markers that
+ * might be at the tail of the lists due to arc_evict_state().
+ */
+
+ for (data_hdr = multilist_sublist_tail(data_mls); data_hdr != NULL;
+ data_hdr = multilist_sublist_prev(data_mls, data_hdr)) {
+ if (data_hdr->b_spa != 0)
+ break;
+ }
+
+ for (meta_hdr = multilist_sublist_tail(meta_mls); meta_hdr != NULL;
+ meta_hdr = multilist_sublist_prev(meta_mls, meta_hdr)) {
+ if (meta_hdr->b_spa != 0)
+ break;
+ }
+
+ if (data_hdr == NULL && meta_hdr == NULL) {
+ type = ARC_BUFC_DATA;
+ } else if (data_hdr == NULL) {
+ ASSERT3P(meta_hdr, !=, NULL);
+ type = ARC_BUFC_METADATA;
+ } else if (meta_hdr == NULL) {
+ ASSERT3P(data_hdr, !=, NULL);
+ type = ARC_BUFC_DATA;
+ } else {
+ ASSERT3P(data_hdr, !=, NULL);
+ ASSERT3P(meta_hdr, !=, NULL);
+
+ /* The headers can't be on the sublist without an L1 header */
+ ASSERT(HDR_HAS_L1HDR(data_hdr));
+ ASSERT(HDR_HAS_L1HDR(meta_hdr));
+
+ if (data_hdr->b_l1hdr.b_arc_access <
+ meta_hdr->b_l1hdr.b_arc_access) {
+ type = ARC_BUFC_DATA;
+ } else {
+ type = ARC_BUFC_METADATA;
+ }
+ }
+
+ multilist_sublist_unlock(meta_mls);
+ multilist_sublist_unlock(data_mls);
+
+ return (type);
+}
+
+/*
+ * Evict buffers from the cache, such that arc_size is capped by arc_c.
+ */
+static uint64_t
+arc_evict(void)
+{
+ uint64_t total_evicted = 0;
+ uint64_t bytes;
+ int64_t target;
+ uint64_t asize = aggsum_value(&arc_size);
+ uint64_t ameta = aggsum_value(&arc_meta_used);
+
+ /*
+ * If we're over arc_meta_limit, we want to correct that before
+ * potentially evicting data buffers below.
+ */
+ total_evicted += arc_evict_meta(ameta);
+
+ /*
+ * Adjust MRU size
+ *
+ * If we're over the target cache size, we want to evict enough
+ * from the list to get back to our target size. We don't want
+ * to evict too much from the MRU, such that it drops below
+ * arc_p. So, if we're over our target cache size more than
+ * the MRU is over arc_p, we'll evict enough to get back to
+ * arc_p here, and then evict more from the MFU below.
+ */
+ target = MIN((int64_t)(asize - arc_c),
+ (int64_t)(zfs_refcount_count(&arc_anon->arcs_size) +
+ zfs_refcount_count(&arc_mru->arcs_size) + ameta - arc_p));
+
+ /*
+ * If we're below arc_meta_min, always prefer to evict data.
+ * Otherwise, try to satisfy the requested number of bytes to
+ * evict from the type which contains older buffers; in an
+ * effort to keep newer buffers in the cache regardless of their
+ * type. If we cannot satisfy the number of bytes from this
+ * type, spill over into the next type.
+ */
+ if (arc_evict_type(arc_mru) == ARC_BUFC_METADATA &&
+ ameta > arc_meta_min) {
+ bytes = arc_evict_impl(arc_mru, 0, target, ARC_BUFC_METADATA);
+ total_evicted += bytes;
+
+ /*
+ * If we couldn't evict our target number of bytes from
+ * metadata, we try to get the rest from data.
+ */
+ target -= bytes;
+
+ total_evicted +=
+ arc_evict_impl(arc_mru, 0, target, ARC_BUFC_DATA);
+ } else {
+ bytes = arc_evict_impl(arc_mru, 0, target, ARC_BUFC_DATA);
+ total_evicted += bytes;
+
+ /*
+ * If we couldn't evict our target number of bytes from
+ * data, we try to get the rest from metadata.
+ */
+ target -= bytes;
+
+ total_evicted +=
+ arc_evict_impl(arc_mru, 0, target, ARC_BUFC_METADATA);
+ }
+
+ /*
+ * Re-sum ARC stats after the first round of evictions.
+ */
+ asize = aggsum_value(&arc_size);
+ ameta = aggsum_value(&arc_meta_used);
+
+
+ /*
+ * Adjust MFU size
+ *
+ * Now that we've tried to evict enough from the MRU to get its
+ * size back to arc_p, if we're still above the target cache
+ * size, we evict the rest from the MFU.
+ */
+ target = asize - arc_c;
+
+ if (arc_evict_type(arc_mfu) == ARC_BUFC_METADATA &&
+ ameta > arc_meta_min) {
+ bytes = arc_evict_impl(arc_mfu, 0, target, ARC_BUFC_METADATA);
+ total_evicted += bytes;
+
+ /*
+ * If we couldn't evict our target number of bytes from
+ * metadata, we try to get the rest from data.
+ */
+ target -= bytes;
+
+ total_evicted +=
+ arc_evict_impl(arc_mfu, 0, target, ARC_BUFC_DATA);
+ } else {
+ bytes = arc_evict_impl(arc_mfu, 0, target, ARC_BUFC_DATA);
+ total_evicted += bytes;
+
+ /*
+ * If we couldn't evict our target number of bytes from
+ * data, we try to get the rest from data.
+ */
+ target -= bytes;
+
+ total_evicted +=
+ arc_evict_impl(arc_mfu, 0, target, ARC_BUFC_METADATA);
+ }
+
+ /*
+ * Adjust ghost lists
+ *
+ * In addition to the above, the ARC also defines target values
+ * for the ghost lists. The sum of the mru list and mru ghost
+ * list should never exceed the target size of the cache, and
+ * the sum of the mru list, mfu list, mru ghost list, and mfu
+ * ghost list should never exceed twice the target size of the
+ * cache. The following logic enforces these limits on the ghost
+ * caches, and evicts from them as needed.
+ */
+ target = zfs_refcount_count(&arc_mru->arcs_size) +
+ zfs_refcount_count(&arc_mru_ghost->arcs_size) - arc_c;
+
+ bytes = arc_evict_impl(arc_mru_ghost, 0, target, ARC_BUFC_DATA);
+ total_evicted += bytes;
+
+ target -= bytes;
+
+ total_evicted +=
+ arc_evict_impl(arc_mru_ghost, 0, target, ARC_BUFC_METADATA);
+
+ /*
+ * We assume the sum of the mru list and mfu list is less than
+ * or equal to arc_c (we enforced this above), which means we
+ * can use the simpler of the two equations below:
+ *
+ * mru + mfu + mru ghost + mfu ghost <= 2 * arc_c
+ * mru ghost + mfu ghost <= arc_c
+ */
+ target = zfs_refcount_count(&arc_mru_ghost->arcs_size) +
+ zfs_refcount_count(&arc_mfu_ghost->arcs_size) - arc_c;
+
+ bytes = arc_evict_impl(arc_mfu_ghost, 0, target, ARC_BUFC_DATA);
+ total_evicted += bytes;
+
+ target -= bytes;
+
+ total_evicted +=
+ arc_evict_impl(arc_mfu_ghost, 0, target, ARC_BUFC_METADATA);
+
+ return (total_evicted);
+}
+
+void
+arc_flush(spa_t *spa, boolean_t retry)
+{
+ uint64_t guid = 0;
+
+ /*
+ * If retry is B_TRUE, a spa must not be specified since we have
+ * no good way to determine if all of a spa's buffers have been
+ * evicted from an arc state.
+ */
+ ASSERT(!retry || spa == 0);
+
+ if (spa != NULL)
+ guid = spa_load_guid(spa);
+
+ (void) arc_flush_state(arc_mru, guid, ARC_BUFC_DATA, retry);
+ (void) arc_flush_state(arc_mru, guid, ARC_BUFC_METADATA, retry);
+
+ (void) arc_flush_state(arc_mfu, guid, ARC_BUFC_DATA, retry);
+ (void) arc_flush_state(arc_mfu, guid, ARC_BUFC_METADATA, retry);
+
+ (void) arc_flush_state(arc_mru_ghost, guid, ARC_BUFC_DATA, retry);
+ (void) arc_flush_state(arc_mru_ghost, guid, ARC_BUFC_METADATA, retry);
+
+ (void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_DATA, retry);
+ (void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_METADATA, retry);
+}
+
+void
+arc_reduce_target_size(int64_t to_free)
+{
+ uint64_t asize = aggsum_value(&arc_size);
+
+ /*
+ * All callers want the ARC to actually evict (at least) this much
+ * memory. Therefore we reduce from the lower of the current size and
+ * the target size. This way, even if arc_c is much higher than
+ * arc_size (as can be the case after many calls to arc_freed(), we will
+ * immediately have arc_c < arc_size and therefore the arc_evict_zthr
+ * will evict.
+ */
+ uint64_t c = MIN(arc_c, asize);
+
+ if (c > to_free && c - to_free > arc_c_min) {
+ arc_c = c - to_free;
+ atomic_add_64(&arc_p, -(arc_p >> arc_shrink_shift));
+ if (arc_p > arc_c)
+ arc_p = (arc_c >> 1);
+ ASSERT(arc_c >= arc_c_min);
+ ASSERT((int64_t)arc_p >= 0);
+ } else {
+ arc_c = arc_c_min;
+ }
+
+ if (asize > arc_c) {
+ /* See comment in arc_evict_cb_check() on why lock+flag */
+ mutex_enter(&arc_evict_lock);
+ arc_evict_needed = B_TRUE;
+ mutex_exit(&arc_evict_lock);
+ zthr_wakeup(arc_evict_zthr);
+ }
+}
+
+/*
+ * Determine if the system is under memory pressure and is asking
+ * to reclaim memory. A return value of B_TRUE indicates that the system
+ * is under memory pressure and that the arc should adjust accordingly.
+ */
+boolean_t
+arc_reclaim_needed(void)
+{
+ return (arc_available_memory() < 0);
+}
+
+void
+arc_kmem_reap_soon(void)
+{
+ size_t i;
+ kmem_cache_t *prev_cache = NULL;
+ kmem_cache_t *prev_data_cache = NULL;
+ extern kmem_cache_t *zio_buf_cache[];
+ extern kmem_cache_t *zio_data_buf_cache[];
+
+#ifdef _KERNEL
+ if ((aggsum_compare(&arc_meta_used, arc_meta_limit) >= 0) &&
+ zfs_arc_meta_prune) {
+ /*
+ * We are exceeding our meta-data cache limit.
+ * Prune some entries to release holds on meta-data.
+ */
+ arc_prune_async(zfs_arc_meta_prune);
+ }
+#if defined(_ILP32)
+ /*
+ * Reclaim unused memory from all kmem caches.
+ */
+ kmem_reap();
+#endif
+#endif
+
+ for (i = 0; i < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT; i++) {
+#if defined(_ILP32)
+ /* reach upper limit of cache size on 32-bit */
+ if (zio_buf_cache[i] == NULL)
+ break;
+#endif
+ if (zio_buf_cache[i] != prev_cache) {
+ prev_cache = zio_buf_cache[i];
+ kmem_cache_reap_now(zio_buf_cache[i]);
+ }
+ if (zio_data_buf_cache[i] != prev_data_cache) {
+ prev_data_cache = zio_data_buf_cache[i];
+ kmem_cache_reap_now(zio_data_buf_cache[i]);
+ }
+ }
+ kmem_cache_reap_now(buf_cache);
+ kmem_cache_reap_now(hdr_full_cache);
+ kmem_cache_reap_now(hdr_l2only_cache);
+ kmem_cache_reap_now(zfs_btree_leaf_cache);
+ abd_cache_reap_now();
+}
+
+/* ARGSUSED */
+static boolean_t
+arc_evict_cb_check(void *arg, zthr_t *zthr)
+{
+ /*
+ * This is necessary so that any changes which may have been made to
+ * many of the zfs_arc_* module parameters will be propagated to
+ * their actual internal variable counterparts. Without this,
+ * changing those module params at runtime would have no effect.
+ */
+ arc_tuning_update(B_FALSE);
+
+ /*
+ * This is necessary in order to keep the kstat information
+ * up to date for tools that display kstat data such as the
+ * mdb ::arc dcmd and the Linux crash utility. These tools
+ * typically do not call kstat's update function, but simply
+ * dump out stats from the most recent update. Without
+ * this call, these commands may show stale stats for the
+ * anon, mru, mru_ghost, mfu, and mfu_ghost lists. Even
+ * with this change, the data might be up to 1 second
+ * out of date(the arc_evict_zthr has a maximum sleep
+ * time of 1 second); but that should suffice. The
+ * arc_state_t structures can be queried directly if more
+ * accurate information is needed.
+ */
+ if (arc_ksp != NULL)
+ arc_ksp->ks_update(arc_ksp, KSTAT_READ);
+
+ /*
+ * We have to rely on arc_wait_for_eviction() to tell us when to
+ * evict, rather than checking if we are overflowing here, so that we
+ * are sure to not leave arc_wait_for_eviction() waiting on aew_cv.
+ * If we have become "not overflowing" since arc_wait_for_eviction()
+ * checked, we need to wake it up. We could broadcast the CV here,
+ * but arc_wait_for_eviction() may have not yet gone to sleep. We
+ * would need to use a mutex to ensure that this function doesn't
+ * broadcast until arc_wait_for_eviction() has gone to sleep (e.g.
+ * the arc_evict_lock). However, the lock ordering of such a lock
+ * would necessarily be incorrect with respect to the zthr_lock,
+ * which is held before this function is called, and is held by
+ * arc_wait_for_eviction() when it calls zthr_wakeup().
+ */
+ return (arc_evict_needed);
+}
+
+/*
+ * Keep arc_size under arc_c by running arc_evict which evicts data
+ * from the ARC.
+ */
+/* ARGSUSED */
+static void
+arc_evict_cb(void *arg, zthr_t *zthr)
+{
+ uint64_t evicted = 0;
+ fstrans_cookie_t cookie = spl_fstrans_mark();
+
+ /* Evict from cache */
+ evicted = arc_evict();
+
+ /*
+ * If evicted is zero, we couldn't evict anything
+ * via arc_evict(). This could be due to hash lock
+ * collisions, but more likely due to the majority of
+ * arc buffers being unevictable. Therefore, even if
+ * arc_size is above arc_c, another pass is unlikely to
+ * be helpful and could potentially cause us to enter an
+ * infinite loop. Additionally, zthr_iscancelled() is
+ * checked here so that if the arc is shutting down, the
+ * broadcast will wake any remaining arc evict waiters.
+ */
+ mutex_enter(&arc_evict_lock);
+ arc_evict_needed = !zthr_iscancelled(arc_evict_zthr) &&
+ evicted > 0 && aggsum_compare(&arc_size, arc_c) > 0;
+ if (!arc_evict_needed) {
+ /*
+ * We're either no longer overflowing, or we
+ * can't evict anything more, so we should wake
+ * arc_get_data_impl() sooner.
+ */
+ arc_evict_waiter_t *aw;
+ while ((aw = list_remove_head(&arc_evict_waiters)) != NULL) {
+ cv_broadcast(&aw->aew_cv);
+ }
+ arc_set_need_free();
+ }
+ mutex_exit(&arc_evict_lock);
+ spl_fstrans_unmark(cookie);
+}
+
+/* ARGSUSED */
+static boolean_t
+arc_reap_cb_check(void *arg, zthr_t *zthr)
+{
+ int64_t free_memory = arc_available_memory();
+
+ /*
+ * If a kmem reap is already active, don't schedule more. We must
+ * check for this because kmem_cache_reap_soon() won't actually
+ * block on the cache being reaped (this is to prevent callers from
+ * becoming implicitly blocked by a system-wide kmem reap -- which,
+ * on a system with many, many full magazines, can take minutes).
+ */
+ if (!kmem_cache_reap_active() && free_memory < 0) {
+
+ arc_no_grow = B_TRUE;
+ arc_warm = B_TRUE;
+ /*
+ * Wait at least zfs_grow_retry (default 5) seconds
+ * before considering growing.
+ */
+ arc_growtime = gethrtime() + SEC2NSEC(arc_grow_retry);
+ return (B_TRUE);
+ } else if (free_memory < arc_c >> arc_no_grow_shift) {
+ arc_no_grow = B_TRUE;
+ } else if (gethrtime() >= arc_growtime) {
+ arc_no_grow = B_FALSE;
+ }
+
+ return (B_FALSE);
+}
+
+/*
+ * Keep enough free memory in the system by reaping the ARC's kmem
+ * caches. To cause more slabs to be reapable, we may reduce the
+ * target size of the cache (arc_c), causing the arc_evict_cb()
+ * to free more buffers.
+ */
+/* ARGSUSED */
+static void
+arc_reap_cb(void *arg, zthr_t *zthr)
+{
+ int64_t free_memory;
+ fstrans_cookie_t cookie = spl_fstrans_mark();
+
+ /*
+ * Kick off asynchronous kmem_reap()'s of all our caches.
+ */
+ arc_kmem_reap_soon();
+
+ /*
+ * Wait at least arc_kmem_cache_reap_retry_ms between
+ * arc_kmem_reap_soon() calls. Without this check it is possible to
+ * end up in a situation where we spend lots of time reaping
+ * caches, while we're near arc_c_min. Waiting here also gives the
+ * subsequent free memory check a chance of finding that the
+ * asynchronous reap has already freed enough memory, and we don't
+ * need to call arc_reduce_target_size().
+ */
+ delay((hz * arc_kmem_cache_reap_retry_ms + 999) / 1000);
+
+ /*
+ * Reduce the target size as needed to maintain the amount of free
+ * memory in the system at a fraction of the arc_size (1/128th by
+ * default). If oversubscribed (free_memory < 0) then reduce the
+ * target arc_size by the deficit amount plus the fractional
+ * amount. If free memory is positive but less then the fractional
+ * amount, reduce by what is needed to hit the fractional amount.
+ */
+ free_memory = arc_available_memory();
+
+ int64_t to_free =
+ (arc_c >> arc_shrink_shift) - free_memory;
+ if (to_free > 0) {
+ arc_reduce_target_size(to_free);
+ }
+ spl_fstrans_unmark(cookie);
+}
+
+#ifdef _KERNEL
+/*
+ * Determine the amount of memory eligible for eviction contained in the
+ * ARC. All clean data reported by the ghost lists can always be safely
+ * evicted. Due to arc_c_min, the same does not hold for all clean data
+ * contained by the regular mru and mfu lists.
+ *
+ * In the case of the regular mru and mfu lists, we need to report as
+ * much clean data as possible, such that evicting that same reported
+ * data will not bring arc_size below arc_c_min. Thus, in certain
+ * circumstances, the total amount of clean data in the mru and mfu
+ * lists might not actually be evictable.
+ *
+ * The following two distinct cases are accounted for:
+ *
+ * 1. The sum of the amount of dirty data contained by both the mru and
+ * mfu lists, plus the ARC's other accounting (e.g. the anon list),
+ * is greater than or equal to arc_c_min.
+ * (i.e. amount of dirty data >= arc_c_min)
+ *
+ * This is the easy case; all clean data contained by the mru and mfu
+ * lists is evictable. Evicting all clean data can only drop arc_size
+ * to the amount of dirty data, which is greater than arc_c_min.
+ *
+ * 2. The sum of the amount of dirty data contained by both the mru and
+ * mfu lists, plus the ARC's other accounting (e.g. the anon list),
+ * is less than arc_c_min.
+ * (i.e. arc_c_min > amount of dirty data)
+ *
+ * 2.1. arc_size is greater than or equal arc_c_min.
+ * (i.e. arc_size >= arc_c_min > amount of dirty data)
+ *
+ * In this case, not all clean data from the regular mru and mfu
+ * lists is actually evictable; we must leave enough clean data
+ * to keep arc_size above arc_c_min. Thus, the maximum amount of
+ * evictable data from the two lists combined, is exactly the
+ * difference between arc_size and arc_c_min.
+ *
+ * 2.2. arc_size is less than arc_c_min
+ * (i.e. arc_c_min > arc_size > amount of dirty data)
+ *
+ * In this case, none of the data contained in the mru and mfu
+ * lists is evictable, even if it's clean. Since arc_size is
+ * already below arc_c_min, evicting any more would only
+ * increase this negative difference.
+ */
+
+#endif /* _KERNEL */
+
+/*
+ * Adapt arc info given the number of bytes we are trying to add and
+ * the state that we are coming from. This function is only called
+ * when we are adding new content to the cache.
+ */
+static void
+arc_adapt(int bytes, arc_state_t *state)
+{
+ int mult;
+ uint64_t arc_p_min = (arc_c >> arc_p_min_shift);
+ int64_t mrug_size = zfs_refcount_count(&arc_mru_ghost->arcs_size);
+ int64_t mfug_size = zfs_refcount_count(&arc_mfu_ghost->arcs_size);
+
+ ASSERT(bytes > 0);
+ /*
+ * Adapt the target size of the MRU list:
+ * - if we just hit in the MRU ghost list, then increase
+ * the target size of the MRU list.
+ * - if we just hit in the MFU ghost list, then increase
+ * the target size of the MFU list by decreasing the
+ * target size of the MRU list.
+ */
+ if (state == arc_mru_ghost) {
+ mult = (mrug_size >= mfug_size) ? 1 : (mfug_size / mrug_size);
+ if (!zfs_arc_p_dampener_disable)
+ mult = MIN(mult, 10); /* avoid wild arc_p adjustment */
+
+ arc_p = MIN(arc_c - arc_p_min, arc_p + bytes * mult);
+ } else if (state == arc_mfu_ghost) {
+ uint64_t delta;
+
+ mult = (mfug_size >= mrug_size) ? 1 : (mrug_size / mfug_size);
+ if (!zfs_arc_p_dampener_disable)
+ mult = MIN(mult, 10);
+
+ delta = MIN(bytes * mult, arc_p);
+ arc_p = MAX(arc_p_min, arc_p - delta);
+ }
+ ASSERT((int64_t)arc_p >= 0);
+
+ /*
+ * Wake reap thread if we do not have any available memory
+ */
+ if (arc_reclaim_needed()) {
+ zthr_wakeup(arc_reap_zthr);
+ return;
+ }
+
+ if (arc_no_grow)
+ return;
+
+ if (arc_c >= arc_c_max)
+ return;
+
+ /*
+ * If we're within (2 * maxblocksize) bytes of the target
+ * cache size, increment the target cache size
+ */
+ ASSERT3U(arc_c, >=, 2ULL << SPA_MAXBLOCKSHIFT);
+ if (aggsum_upper_bound(&arc_size) >=
+ arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) {
+ atomic_add_64(&arc_c, (int64_t)bytes);
+ if (arc_c > arc_c_max)
+ arc_c = arc_c_max;
+ else if (state == arc_anon)
+ atomic_add_64(&arc_p, (int64_t)bytes);
+ if (arc_p > arc_c)
+ arc_p = arc_c;
+ }
+ ASSERT((int64_t)arc_p >= 0);
+}
+
+/*
+ * Check if arc_size has grown past our upper threshold, determined by
+ * zfs_arc_overflow_shift.
+ */
+boolean_t
+arc_is_overflowing(void)
+{
+ /* Always allow at least one block of overflow */
+ int64_t overflow = MAX(SPA_MAXBLOCKSIZE,
+ arc_c >> zfs_arc_overflow_shift);
+
+ /*
+ * We just compare the lower bound here for performance reasons. Our
+ * primary goals are to make sure that the arc never grows without
+ * bound, and that it can reach its maximum size. This check
+ * accomplishes both goals. The maximum amount we could run over by is
+ * 2 * aggsum_borrow_multiplier * NUM_CPUS * the average size of a block
+ * in the ARC. In practice, that's in the tens of MB, which is low
+ * enough to be safe.
+ */
+ return (aggsum_lower_bound(&arc_size) >= (int64_t)arc_c + overflow);
+}
+
+static abd_t *
+arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, void *tag,
+ boolean_t do_adapt)
+{
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ arc_get_data_impl(hdr, size, tag, do_adapt);
+ if (type == ARC_BUFC_METADATA) {
+ return (abd_alloc(size, B_TRUE));
+ } else {
+ ASSERT(type == ARC_BUFC_DATA);
+ return (abd_alloc(size, B_FALSE));
+ }
+}
+
+static void *
+arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+{
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ arc_get_data_impl(hdr, size, tag, B_TRUE);
+ if (type == ARC_BUFC_METADATA) {
+ return (zio_buf_alloc(size));
+ } else {
+ ASSERT(type == ARC_BUFC_DATA);
+ return (zio_data_buf_alloc(size));
+ }
+}
+
+/*
+ * Wait for the specified amount of data (in bytes) to be evicted from the
+ * ARC, and for there to be sufficient free memory in the system. Waiting for
+ * eviction ensures that the memory used by the ARC decreases. Waiting for
+ * free memory ensures that the system won't run out of free pages, regardless
+ * of ARC behavior and settings. See arc_lowmem_init().
+ */
+void
+arc_wait_for_eviction(uint64_t amount)
+{
+ mutex_enter(&arc_evict_lock);
+ if (arc_is_overflowing()) {
+ arc_evict_needed = B_TRUE;
+ zthr_wakeup(arc_evict_zthr);
+
+ if (amount != 0) {
+ arc_evict_waiter_t aw;
+ list_link_init(&aw.aew_node);
+ cv_init(&aw.aew_cv, NULL, CV_DEFAULT, NULL);
+
+ arc_evict_waiter_t *last =
+ list_tail(&arc_evict_waiters);
+ if (last != NULL) {
+ ASSERT3U(last->aew_count, >, arc_evict_count);
+ aw.aew_count = last->aew_count + amount;
+ } else {
+ aw.aew_count = arc_evict_count + amount;
+ }
+
+ list_insert_tail(&arc_evict_waiters, &aw);
+
+ arc_set_need_free();
+
+ DTRACE_PROBE3(arc__wait__for__eviction,
+ uint64_t, amount,
+ uint64_t, arc_evict_count,
+ uint64_t, aw.aew_count);
+
+ /*
+ * We will be woken up either when arc_evict_count
+ * reaches aew_count, or when the ARC is no longer
+ * overflowing and eviction completes.
+ */
+ cv_wait(&aw.aew_cv, &arc_evict_lock);
+
+ /*
+ * In case of "false" wakeup, we will still be on the
+ * list.
+ */
+ if (list_link_active(&aw.aew_node))
+ list_remove(&arc_evict_waiters, &aw);
+
+ cv_destroy(&aw.aew_cv);
+ }
+ }
+ mutex_exit(&arc_evict_lock);
+}
+
+/*
+ * Allocate a block and return it to the caller. If we are hitting the
+ * hard limit for the cache size, we must sleep, waiting for the eviction
+ * thread to catch up. If we're past the target size but below the hard
+ * limit, we'll only signal the reclaim thread and continue on.
+ */
+static void
+arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag,
+ boolean_t do_adapt)
+{
+ arc_state_t *state = hdr->b_l1hdr.b_state;
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ if (do_adapt)
+ arc_adapt(size, state);
+
+ /*
+ * If arc_size is currently overflowing, we must be adding data
+ * faster than we are evicting. To ensure we don't compound the
+ * problem by adding more data and forcing arc_size to grow even
+ * further past it's target size, we wait for the eviction thread to
+ * make some progress. We also wait for there to be sufficient free
+ * memory in the system, as measured by arc_free_memory().
+ *
+ * Specifically, we wait for zfs_arc_eviction_pct percent of the
+ * requested size to be evicted. This should be more than 100%, to
+ * ensure that that progress is also made towards getting arc_size
+ * under arc_c. See the comment above zfs_arc_eviction_pct.
+ *
+ * We do the overflowing check without holding the arc_evict_lock to
+ * reduce lock contention in this hot path. Note that
+ * arc_wait_for_eviction() will acquire the lock and check again to
+ * ensure we are truly overflowing before blocking.
+ */
+ if (arc_is_overflowing()) {
+ arc_wait_for_eviction(size *
+ zfs_arc_eviction_pct / 100);
+ }
+
+ VERIFY3U(hdr->b_type, ==, type);
+ if (type == ARC_BUFC_METADATA) {
+ arc_space_consume(size, ARC_SPACE_META);
+ } else {
+ arc_space_consume(size, ARC_SPACE_DATA);
+ }
+
+ /*
+ * Update the state size. Note that ghost states have a
+ * "ghost size" and so don't need to be updated.
+ */
+ if (!GHOST_STATE(state)) {
+
+ (void) zfs_refcount_add_many(&state->arcs_size, size, tag);
+
+ /*
+ * If this is reached via arc_read, the link is
+ * protected by the hash lock. If reached via
+ * arc_buf_alloc, the header should not be accessed by
+ * any other thread. And, if reached via arc_read_done,
+ * the hash lock will protect it if it's found in the
+ * hash table; otherwise no other thread should be
+ * trying to [add|remove]_reference it.
+ */
+ if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+ (void) zfs_refcount_add_many(&state->arcs_esize[type],
+ size, tag);
+ }
+
+ /*
+ * If we are growing the cache, and we are adding anonymous
+ * data, and we have outgrown arc_p, update arc_p
+ */
+ if (aggsum_upper_bound(&arc_size) < arc_c &&
+ hdr->b_l1hdr.b_state == arc_anon &&
+ (zfs_refcount_count(&arc_anon->arcs_size) +
+ zfs_refcount_count(&arc_mru->arcs_size) > arc_p))
+ arc_p = MIN(arc_c, arc_p + size);
+ }
+}
+
+static void
+arc_free_data_abd(arc_buf_hdr_t *hdr, abd_t *abd, uint64_t size, void *tag)
+{
+ arc_free_data_impl(hdr, size, tag);
+ abd_free(abd);
+}
+
+static void
+arc_free_data_buf(arc_buf_hdr_t *hdr, void *buf, uint64_t size, void *tag)
+{
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ arc_free_data_impl(hdr, size, tag);
+ if (type == ARC_BUFC_METADATA) {
+ zio_buf_free(buf, size);
+ } else {
+ ASSERT(type == ARC_BUFC_DATA);
+ zio_data_buf_free(buf, size);
+ }
+}
+
+/*
+ * Free the arc data buffer.
+ */
+static void
+arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+{
+ arc_state_t *state = hdr->b_l1hdr.b_state;
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ /* protected by hash lock, if in the hash table */
+ if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+ ASSERT(state != arc_anon && state != arc_l2c_only);
+
+ (void) zfs_refcount_remove_many(&state->arcs_esize[type],
+ size, tag);
+ }
+ (void) zfs_refcount_remove_many(&state->arcs_size, size, tag);
+
+ VERIFY3U(hdr->b_type, ==, type);
+ if (type == ARC_BUFC_METADATA) {
+ arc_space_return(size, ARC_SPACE_META);
+ } else {
+ ASSERT(type == ARC_BUFC_DATA);
+ arc_space_return(size, ARC_SPACE_DATA);
+ }
+}
+
+/*
+ * This routine is called whenever a buffer is accessed.
+ * NOTE: the hash lock is dropped in this function.
+ */
+static void
+arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
+{
+ clock_t now;
+
+ ASSERT(MUTEX_HELD(hash_lock));
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ if (hdr->b_l1hdr.b_state == arc_anon) {
+ /*
+ * This buffer is not in the cache, and does not
+ * appear in our "ghost" list. Add the new buffer
+ * to the MRU state.
+ */
+
+ ASSERT0(hdr->b_l1hdr.b_arc_access);
+ hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
+ DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, hdr);
+ arc_change_state(arc_mru, hdr, hash_lock);
+
+ } else if (hdr->b_l1hdr.b_state == arc_mru) {
+ now = ddi_get_lbolt();
+
+ /*
+ * If this buffer is here because of a prefetch, then either:
+ * - clear the flag if this is a "referencing" read
+ * (any subsequent access will bump this into the MFU state).
+ * or
+ * - move the buffer to the head of the list if this is
+ * another prefetch (to make it less likely to be evicted).
+ */
+ if (HDR_PREFETCH(hdr) || HDR_PRESCIENT_PREFETCH(hdr)) {
+ if (zfs_refcount_count(&hdr->b_l1hdr.b_refcnt) == 0) {
+ /* link protected by hash lock */
+ ASSERT(multilist_link_active(
+ &hdr->b_l1hdr.b_arc_node));
+ } else {
+ arc_hdr_clear_flags(hdr,
+ ARC_FLAG_PREFETCH |
+ ARC_FLAG_PRESCIENT_PREFETCH);
+ atomic_inc_32(&hdr->b_l1hdr.b_mru_hits);
+ ARCSTAT_BUMP(arcstat_mru_hits);
+ }
+ hdr->b_l1hdr.b_arc_access = now;
+ return;
+ }
+
+ /*
+ * This buffer has been "accessed" only once so far,
+ * but it is still in the cache. Move it to the MFU
+ * state.
+ */
+ if (ddi_time_after(now, hdr->b_l1hdr.b_arc_access +
+ ARC_MINTIME)) {
+ /*
+ * More than 125ms have passed since we
+ * instantiated this buffer. Move it to the
+ * most frequently used state.
+ */
+ hdr->b_l1hdr.b_arc_access = now;
+ DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
+ arc_change_state(arc_mfu, hdr, hash_lock);
+ }
+ atomic_inc_32(&hdr->b_l1hdr.b_mru_hits);
+ ARCSTAT_BUMP(arcstat_mru_hits);
+ } else if (hdr->b_l1hdr.b_state == arc_mru_ghost) {
+ arc_state_t *new_state;
+ /*
+ * This buffer has been "accessed" recently, but
+ * was evicted from the cache. Move it to the
+ * MFU state.
+ */
+
+ if (HDR_PREFETCH(hdr) || HDR_PRESCIENT_PREFETCH(hdr)) {
+ new_state = arc_mru;
+ if (zfs_refcount_count(&hdr->b_l1hdr.b_refcnt) > 0) {
+ arc_hdr_clear_flags(hdr,
+ ARC_FLAG_PREFETCH |
+ ARC_FLAG_PRESCIENT_PREFETCH);
+ }
+ DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, hdr);
+ } else {
+ new_state = arc_mfu;
+ DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
+ }
+
+ hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
+ arc_change_state(new_state, hdr, hash_lock);
+
+ atomic_inc_32(&hdr->b_l1hdr.b_mru_ghost_hits);
+ ARCSTAT_BUMP(arcstat_mru_ghost_hits);
+ } else if (hdr->b_l1hdr.b_state == arc_mfu) {
+ /*
+ * This buffer has been accessed more than once and is
+ * still in the cache. Keep it in the MFU state.
+ *
+ * NOTE: an add_reference() that occurred when we did
+ * the arc_read() will have kicked this off the list.
+ * If it was a prefetch, we will explicitly move it to
+ * the head of the list now.
+ */
+
+ atomic_inc_32(&hdr->b_l1hdr.b_mfu_hits);
+ ARCSTAT_BUMP(arcstat_mfu_hits);
+ hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
+ } else if (hdr->b_l1hdr.b_state == arc_mfu_ghost) {
+ arc_state_t *new_state = arc_mfu;
+ /*
+ * This buffer has been accessed more than once but has
+ * been evicted from the cache. Move it back to the
+ * MFU state.
+ */
+
+ if (HDR_PREFETCH(hdr) || HDR_PRESCIENT_PREFETCH(hdr)) {
+ /*
+ * This is a prefetch access...
+ * move this block back to the MRU state.
+ */
+ new_state = arc_mru;
+ }
+
+ hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
+ DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
+ arc_change_state(new_state, hdr, hash_lock);
+
+ atomic_inc_32(&hdr->b_l1hdr.b_mfu_ghost_hits);
+ ARCSTAT_BUMP(arcstat_mfu_ghost_hits);
+ } else if (hdr->b_l1hdr.b_state == arc_l2c_only) {
+ /*
+ * This buffer is on the 2nd Level ARC.
+ */
+
+ hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
+ DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
+ arc_change_state(arc_mfu, hdr, hash_lock);
+ } else {
+ cmn_err(CE_PANIC, "invalid arc state 0x%p",
+ hdr->b_l1hdr.b_state);
+ }
+}
+
+/*
+ * This routine is called by dbuf_hold() to update the arc_access() state
+ * which otherwise would be skipped for entries in the dbuf cache.
+ */
+void
+arc_buf_access(arc_buf_t *buf)
+{
+ mutex_enter(&buf->b_evict_lock);
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ /*
+ * Avoid taking the hash_lock when possible as an optimization.
+ * The header must be checked again under the hash_lock in order
+ * to handle the case where it is concurrently being released.
+ */
+ if (hdr->b_l1hdr.b_state == arc_anon || HDR_EMPTY(hdr)) {
+ mutex_exit(&buf->b_evict_lock);
+ return;
+ }
+
+ kmutex_t *hash_lock = HDR_LOCK(hdr);
+ mutex_enter(hash_lock);
+
+ if (hdr->b_l1hdr.b_state == arc_anon || HDR_EMPTY(hdr)) {
+ mutex_exit(hash_lock);
+ mutex_exit(&buf->b_evict_lock);
+ ARCSTAT_BUMP(arcstat_access_skip);
+ return;
+ }
+
+ mutex_exit(&buf->b_evict_lock);
+
+ ASSERT(hdr->b_l1hdr.b_state == arc_mru ||
+ hdr->b_l1hdr.b_state == arc_mfu);
+
+ DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr);
+ arc_access(hdr, hash_lock);
+ mutex_exit(hash_lock);
+
+ ARCSTAT_BUMP(arcstat_hits);
+ ARCSTAT_CONDSTAT(!HDR_PREFETCH(hdr) && !HDR_PRESCIENT_PREFETCH(hdr),
+ demand, prefetch, !HDR_ISTYPE_METADATA(hdr), data, metadata, hits);
+}
+
+/* a generic arc_read_done_func_t which you can use */
+/* ARGSUSED */
+void
+arc_bcopy_func(zio_t *zio, const zbookmark_phys_t *zb, const blkptr_t *bp,
+ arc_buf_t *buf, void *arg)
+{
+ if (buf == NULL)
+ return;
+
+ bcopy(buf->b_data, arg, arc_buf_size(buf));
+ arc_buf_destroy(buf, arg);
+}
+
+/* a generic arc_read_done_func_t */
+/* ARGSUSED */
+void
+arc_getbuf_func(zio_t *zio, const zbookmark_phys_t *zb, const blkptr_t *bp,
+ arc_buf_t *buf, void *arg)
+{
+ arc_buf_t **bufp = arg;
+
+ if (buf == NULL) {
+ ASSERT(zio == NULL || zio->io_error != 0);
+ *bufp = NULL;
+ } else {
+ ASSERT(zio == NULL || zio->io_error == 0);
+ *bufp = buf;
+ ASSERT(buf->b_data != NULL);
+ }
+}
+
+static void
+arc_hdr_verify(arc_buf_hdr_t *hdr, blkptr_t *bp)
+{
+ if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp)) {
+ ASSERT3U(HDR_GET_PSIZE(hdr), ==, 0);
+ ASSERT3U(arc_hdr_get_compress(hdr), ==, ZIO_COMPRESS_OFF);
+ } else {
+ if (HDR_COMPRESSION_ENABLED(hdr)) {
+ ASSERT3U(arc_hdr_get_compress(hdr), ==,
+ BP_GET_COMPRESS(bp));
+ }
+ ASSERT3U(HDR_GET_LSIZE(hdr), ==, BP_GET_LSIZE(bp));
+ ASSERT3U(HDR_GET_PSIZE(hdr), ==, BP_GET_PSIZE(bp));
+ ASSERT3U(!!HDR_PROTECTED(hdr), ==, BP_IS_PROTECTED(bp));
+ }
+}
+
+static void
+arc_read_done(zio_t *zio)
+{
+ blkptr_t *bp = zio->io_bp;
+ arc_buf_hdr_t *hdr = zio->io_private;
+ kmutex_t *hash_lock = NULL;
+ arc_callback_t *callback_list;
+ arc_callback_t *acb;
+ boolean_t freeable = B_FALSE;
+
+ /*
+ * The hdr was inserted into hash-table and removed from lists
+ * prior to starting I/O. We should find this header, since
+ * it's in the hash table, and it should be legit since it's
+ * not possible to evict it during the I/O. The only possible
+ * reason for it not to be found is if we were freed during the
+ * read.
+ */
+ if (HDR_IN_HASH_TABLE(hdr)) {
+ arc_buf_hdr_t *found;
+
+ ASSERT3U(hdr->b_birth, ==, BP_PHYSICAL_BIRTH(zio->io_bp));
+ ASSERT3U(hdr->b_dva.dva_word[0], ==,
+ BP_IDENTITY(zio->io_bp)->dva_word[0]);
+ ASSERT3U(hdr->b_dva.dva_word[1], ==,
+ BP_IDENTITY(zio->io_bp)->dva_word[1]);
+
+ found = buf_hash_find(hdr->b_spa, zio->io_bp, &hash_lock);
+
+ ASSERT((found == hdr &&
+ DVA_EQUAL(&hdr->b_dva, BP_IDENTITY(zio->io_bp))) ||
+ (found == hdr && HDR_L2_READING(hdr)));
+ ASSERT3P(hash_lock, !=, NULL);
+ }
+
+ if (BP_IS_PROTECTED(bp)) {
+ hdr->b_crypt_hdr.b_ot = BP_GET_TYPE(bp);
+ hdr->b_crypt_hdr.b_dsobj = zio->io_bookmark.zb_objset;
+ zio_crypt_decode_params_bp(bp, hdr->b_crypt_hdr.b_salt,
+ hdr->b_crypt_hdr.b_iv);
+
+ if (BP_GET_TYPE(bp) == DMU_OT_INTENT_LOG) {
+ void *tmpbuf;
+
+ tmpbuf = abd_borrow_buf_copy(zio->io_abd,
+ sizeof (zil_chain_t));
+ zio_crypt_decode_mac_zil(tmpbuf,
+ hdr->b_crypt_hdr.b_mac);
+ abd_return_buf(zio->io_abd, tmpbuf,
+ sizeof (zil_chain_t));
+ } else {
+ zio_crypt_decode_mac_bp(bp, hdr->b_crypt_hdr.b_mac);
+ }
+ }
+
+ if (zio->io_error == 0) {
+ /* byteswap if necessary */
+ if (BP_SHOULD_BYTESWAP(zio->io_bp)) {
+ if (BP_GET_LEVEL(zio->io_bp) > 0) {
+ hdr->b_l1hdr.b_byteswap = DMU_BSWAP_UINT64;
+ } else {
+ hdr->b_l1hdr.b_byteswap =
+ DMU_OT_BYTESWAP(BP_GET_TYPE(zio->io_bp));
+ }
+ } else {
+ hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
+ }
+ if (!HDR_L2_READING(hdr)) {
+ hdr->b_complevel = zio->io_prop.zp_complevel;
+ }
+ }
+
+ arc_hdr_clear_flags(hdr, ARC_FLAG_L2_EVICTED);
+ if (l2arc_noprefetch && HDR_PREFETCH(hdr))
+ arc_hdr_clear_flags(hdr, ARC_FLAG_L2CACHE);
+
+ callback_list = hdr->b_l1hdr.b_acb;
+ ASSERT3P(callback_list, !=, NULL);
+
+ if (hash_lock && zio->io_error == 0 &&
+ hdr->b_l1hdr.b_state == arc_anon) {
+ /*
+ * Only call arc_access on anonymous buffers. This is because
+ * if we've issued an I/O for an evicted buffer, we've already
+ * called arc_access (to prevent any simultaneous readers from
+ * getting confused).
+ */
+ arc_access(hdr, hash_lock);
+ }
+
+ /*
+ * If a read request has a callback (i.e. acb_done is not NULL), then we
+ * make a buf containing the data according to the parameters which were
+ * passed in. The implementation of arc_buf_alloc_impl() ensures that we
+ * aren't needlessly decompressing the data multiple times.
+ */
+ int callback_cnt = 0;
+ for (acb = callback_list; acb != NULL; acb = acb->acb_next) {
+ if (!acb->acb_done)
+ continue;
+
+ callback_cnt++;
+
+ if (zio->io_error != 0)
+ continue;
+
+ int error = arc_buf_alloc_impl(hdr, zio->io_spa,
+ &acb->acb_zb, acb->acb_private, acb->acb_encrypted,
+ acb->acb_compressed, acb->acb_noauth, B_TRUE,
+ &acb->acb_buf);
+
+ /*
+ * Assert non-speculative zios didn't fail because an
+ * encryption key wasn't loaded
+ */
+ ASSERT((zio->io_flags & ZIO_FLAG_SPECULATIVE) ||
+ error != EACCES);
+
+ /*
+ * If we failed to decrypt, report an error now (as the zio
+ * layer would have done if it had done the transforms).
+ */
+ if (error == ECKSUM) {
+ ASSERT(BP_IS_PROTECTED(bp));
+ error = SET_ERROR(EIO);
+ if ((zio->io_flags & ZIO_FLAG_SPECULATIVE) == 0) {
+ spa_log_error(zio->io_spa, &acb->acb_zb);
+ zfs_ereport_post(FM_EREPORT_ZFS_AUTHENTICATION,
+ zio->io_spa, NULL, &acb->acb_zb, zio, 0, 0);
+ }
+ }
+
+ if (error != 0) {
+ /*
+ * Decompression or decryption failed. Set
+ * io_error so that when we call acb_done
+ * (below), we will indicate that the read
+ * failed. Note that in the unusual case
+ * where one callback is compressed and another
+ * uncompressed, we will mark all of them
+ * as failed, even though the uncompressed
+ * one can't actually fail. In this case,
+ * the hdr will not be anonymous, because
+ * if there are multiple callbacks, it's
+ * because multiple threads found the same
+ * arc buf in the hash table.
+ */
+ zio->io_error = error;
+ }
+ }
+
+ /*
+ * If there are multiple callbacks, we must have the hash lock,
+ * because the only way for multiple threads to find this hdr is
+ * in the hash table. This ensures that if there are multiple
+ * callbacks, the hdr is not anonymous. If it were anonymous,
+ * we couldn't use arc_buf_destroy() in the error case below.
+ */
+ ASSERT(callback_cnt < 2 || hash_lock != NULL);
+
+ hdr->b_l1hdr.b_acb = NULL;
+ arc_hdr_clear_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
+ if (callback_cnt == 0)
+ ASSERT(hdr->b_l1hdr.b_pabd != NULL || HDR_HAS_RABD(hdr));
+
+ ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt) ||
+ callback_list != NULL);
+
+ if (zio->io_error == 0) {
+ arc_hdr_verify(hdr, zio->io_bp);
+ } else {
+ arc_hdr_set_flags(hdr, ARC_FLAG_IO_ERROR);
+ if (hdr->b_l1hdr.b_state != arc_anon)
+ arc_change_state(arc_anon, hdr, hash_lock);
+ if (HDR_IN_HASH_TABLE(hdr))
+ buf_hash_remove(hdr);
+ freeable = zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt);
+ }
+
+ /*
+ * Broadcast before we drop the hash_lock to avoid the possibility
+ * that the hdr (and hence the cv) might be freed before we get to
+ * the cv_broadcast().
+ */
+ cv_broadcast(&hdr->b_l1hdr.b_cv);
+
+ if (hash_lock != NULL) {
+ mutex_exit(hash_lock);
+ } else {
+ /*
+ * This block was freed while we waited for the read to
+ * complete. It has been removed from the hash table and
+ * moved to the anonymous state (so that it won't show up
+ * in the cache).
+ */
+ ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
+ freeable = zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt);
+ }
+
+ /* execute each callback and free its structure */
+ while ((acb = callback_list) != NULL) {
+ if (acb->acb_done != NULL) {
+ if (zio->io_error != 0 && acb->acb_buf != NULL) {
+ /*
+ * If arc_buf_alloc_impl() fails during
+ * decompression, the buf will still be
+ * allocated, and needs to be freed here.
+ */
+ arc_buf_destroy(acb->acb_buf,
+ acb->acb_private);
+ acb->acb_buf = NULL;
+ }
+ acb->acb_done(zio, &zio->io_bookmark, zio->io_bp,
+ acb->acb_buf, acb->acb_private);
+ }
+
+ if (acb->acb_zio_dummy != NULL) {
+ acb->acb_zio_dummy->io_error = zio->io_error;
+ zio_nowait(acb->acb_zio_dummy);
+ }
+
+ callback_list = acb->acb_next;
+ kmem_free(acb, sizeof (arc_callback_t));
+ }
+
+ if (freeable)
+ arc_hdr_destroy(hdr);
+}
+
+/*
+ * "Read" the block at the specified DVA (in bp) via the
+ * cache. If the block is found in the cache, invoke the provided
+ * callback immediately and return. Note that the `zio' parameter
+ * in the callback will be NULL in this case, since no IO was
+ * required. If the block is not in the cache pass the read request
+ * on to the spa with a substitute callback function, so that the
+ * requested block will be added to the cache.
+ *
+ * If a read request arrives for a block that has a read in-progress,
+ * either wait for the in-progress read to complete (and return the
+ * results); or, if this is a read with a "done" func, add a record
+ * to the read to invoke the "done" func when the read completes,
+ * and return; or just return.
+ *
+ * arc_read_done() will invoke all the requested "done" functions
+ * for readers of this block.
+ */
+int
+arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
+ arc_read_done_func_t *done, void *private, zio_priority_t priority,
+ int zio_flags, arc_flags_t *arc_flags, const zbookmark_phys_t *zb)
+{
+ arc_buf_hdr_t *hdr = NULL;
+ kmutex_t *hash_lock = NULL;
+ zio_t *rzio;
+ uint64_t guid = spa_load_guid(spa);
+ boolean_t compressed_read = (zio_flags & ZIO_FLAG_RAW_COMPRESS) != 0;
+ boolean_t encrypted_read = BP_IS_ENCRYPTED(bp) &&
+ (zio_flags & ZIO_FLAG_RAW_ENCRYPT) != 0;
+ boolean_t noauth_read = BP_IS_AUTHENTICATED(bp) &&
+ (zio_flags & ZIO_FLAG_RAW_ENCRYPT) != 0;
+ boolean_t embedded_bp = !!BP_IS_EMBEDDED(bp);
+ int rc = 0;
+
+ ASSERT(!embedded_bp ||
+ BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA);
+ ASSERT(!BP_IS_HOLE(bp));
+ ASSERT(!BP_IS_REDACTED(bp));
+
+ /*
+ * Normally SPL_FSTRANS will already be set since kernel threads which
+ * expect to call the DMU interfaces will set it when created. System
+ * calls are similarly handled by setting/cleaning the bit in the
+ * registered callback (module/os/.../zfs/zpl_*).
+ *
+ * External consumers such as Lustre which call the exported DMU
+ * interfaces may not have set SPL_FSTRANS. To avoid a deadlock
+ * on the hash_lock always set and clear the bit.
+ */
+ fstrans_cookie_t cookie = spl_fstrans_mark();
+top:
+ if (!embedded_bp) {
+ /*
+ * Embedded BP's have no DVA and require no I/O to "read".
+ * Create an anonymous arc buf to back it.
+ */
+ hdr = buf_hash_find(guid, bp, &hash_lock);
+ }
+
+ /*
+ * Determine if we have an L1 cache hit or a cache miss. For simplicity
+ * we maintain encrypted data separately from compressed / uncompressed
+ * data. If the user is requesting raw encrypted data and we don't have
+ * that in the header we will read from disk to guarantee that we can
+ * get it even if the encryption keys aren't loaded.
+ */
+ if (hdr != NULL && HDR_HAS_L1HDR(hdr) && (HDR_HAS_RABD(hdr) ||
+ (hdr->b_l1hdr.b_pabd != NULL && !encrypted_read))) {
+ arc_buf_t *buf = NULL;
+ *arc_flags |= ARC_FLAG_CACHED;
+
+ if (HDR_IO_IN_PROGRESS(hdr)) {
+ zio_t *head_zio = hdr->b_l1hdr.b_acb->acb_zio_head;
+
+ if (*arc_flags & ARC_FLAG_CACHED_ONLY) {
+ mutex_exit(hash_lock);
+ ARCSTAT_BUMP(arcstat_cached_only_in_progress);
+ rc = SET_ERROR(ENOENT);
+ goto out;
+ }
+
+ ASSERT3P(head_zio, !=, NULL);
+ if ((hdr->b_flags & ARC_FLAG_PRIO_ASYNC_READ) &&
+ priority == ZIO_PRIORITY_SYNC_READ) {
+ /*
+ * This is a sync read that needs to wait for
+ * an in-flight async read. Request that the
+ * zio have its priority upgraded.
+ */
+ zio_change_priority(head_zio, priority);
+ DTRACE_PROBE1(arc__async__upgrade__sync,
+ arc_buf_hdr_t *, hdr);
+ ARCSTAT_BUMP(arcstat_async_upgrade_sync);
+ }
+ if (hdr->b_flags & ARC_FLAG_PREDICTIVE_PREFETCH) {
+ arc_hdr_clear_flags(hdr,
+ ARC_FLAG_PREDICTIVE_PREFETCH);
+ }
+
+ if (*arc_flags & ARC_FLAG_WAIT) {
+ cv_wait(&hdr->b_l1hdr.b_cv, hash_lock);
+ mutex_exit(hash_lock);
+ goto top;
+ }
+ ASSERT(*arc_flags & ARC_FLAG_NOWAIT);
+
+ if (done) {
+ arc_callback_t *acb = NULL;
+
+ acb = kmem_zalloc(sizeof (arc_callback_t),
+ KM_SLEEP);
+ acb->acb_done = done;
+ acb->acb_private = private;
+ acb->acb_compressed = compressed_read;
+ acb->acb_encrypted = encrypted_read;
+ acb->acb_noauth = noauth_read;
+ acb->acb_zb = *zb;
+ if (pio != NULL)
+ acb->acb_zio_dummy = zio_null(pio,
+ spa, NULL, NULL, NULL, zio_flags);
+
+ ASSERT3P(acb->acb_done, !=, NULL);
+ acb->acb_zio_head = head_zio;
+ acb->acb_next = hdr->b_l1hdr.b_acb;
+ hdr->b_l1hdr.b_acb = acb;
+ mutex_exit(hash_lock);
+ goto out;
+ }
+ mutex_exit(hash_lock);
+ goto out;
+ }
+
+ ASSERT(hdr->b_l1hdr.b_state == arc_mru ||
+ hdr->b_l1hdr.b_state == arc_mfu);
+
+ if (done) {
+ if (hdr->b_flags & ARC_FLAG_PREDICTIVE_PREFETCH) {
+ /*
+ * This is a demand read which does not have to
+ * wait for i/o because we did a predictive
+ * prefetch i/o for it, which has completed.
+ */
+ DTRACE_PROBE1(
+ arc__demand__hit__predictive__prefetch,
+ arc_buf_hdr_t *, hdr);
+ ARCSTAT_BUMP(
+ arcstat_demand_hit_predictive_prefetch);
+ arc_hdr_clear_flags(hdr,
+ ARC_FLAG_PREDICTIVE_PREFETCH);
+ }
+
+ if (hdr->b_flags & ARC_FLAG_PRESCIENT_PREFETCH) {
+ ARCSTAT_BUMP(
+ arcstat_demand_hit_prescient_prefetch);
+ arc_hdr_clear_flags(hdr,
+ ARC_FLAG_PRESCIENT_PREFETCH);
+ }
+
+ ASSERT(!embedded_bp || !BP_IS_HOLE(bp));
+
+ /* Get a buf with the desired data in it. */
+ rc = arc_buf_alloc_impl(hdr, spa, zb, private,
+ encrypted_read, compressed_read, noauth_read,
+ B_TRUE, &buf);
+ if (rc == ECKSUM) {
+ /*
+ * Convert authentication and decryption errors
+ * to EIO (and generate an ereport if needed)
+ * before leaving the ARC.
+ */
+ rc = SET_ERROR(EIO);
+ if ((zio_flags & ZIO_FLAG_SPECULATIVE) == 0) {
+ spa_log_error(spa, zb);
+ zfs_ereport_post(
+ FM_EREPORT_ZFS_AUTHENTICATION,
+ spa, NULL, zb, NULL, 0, 0);
+ }
+ }
+ if (rc != 0) {
+ (void) remove_reference(hdr, hash_lock,
+ private);
+ arc_buf_destroy_impl(buf);
+ buf = NULL;
+ }
+
+ /* assert any errors weren't due to unloaded keys */
+ ASSERT((zio_flags & ZIO_FLAG_SPECULATIVE) ||
+ rc != EACCES);
+ } else if (*arc_flags & ARC_FLAG_PREFETCH &&
+ zfs_refcount_count(&hdr->b_l1hdr.b_refcnt) == 0) {
+ arc_hdr_set_flags(hdr, ARC_FLAG_PREFETCH);
+ }
+ DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr);
+ arc_access(hdr, hash_lock);
+ if (*arc_flags & ARC_FLAG_PRESCIENT_PREFETCH)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PRESCIENT_PREFETCH);
+ if (*arc_flags & ARC_FLAG_L2CACHE)
+ arc_hdr_set_flags(hdr, ARC_FLAG_L2CACHE);
+ mutex_exit(hash_lock);
+ ARCSTAT_BUMP(arcstat_hits);
+ ARCSTAT_CONDSTAT(!HDR_PREFETCH(hdr),
+ demand, prefetch, !HDR_ISTYPE_METADATA(hdr),
+ data, metadata, hits);
+
+ if (done)
+ done(NULL, zb, bp, buf, private);
+ } else {
+ uint64_t lsize = BP_GET_LSIZE(bp);
+ uint64_t psize = BP_GET_PSIZE(bp);
+ arc_callback_t *acb;
+ vdev_t *vd = NULL;
+ uint64_t addr = 0;
+ boolean_t devw = B_FALSE;
+ uint64_t size;
+ abd_t *hdr_abd;
+ int alloc_flags = encrypted_read ? ARC_HDR_ALLOC_RDATA : 0;
+
+ if (*arc_flags & ARC_FLAG_CACHED_ONLY) {
+ rc = SET_ERROR(ENOENT);
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+ goto out;
+ }
+
+ /*
+ * Gracefully handle a damaged logical block size as a
+ * checksum error.
+ */
+ if (lsize > spa_maxblocksize(spa)) {
+ rc = SET_ERROR(ECKSUM);
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+ goto out;
+ }
+
+ if (hdr == NULL) {
+ /*
+ * This block is not in the cache or it has
+ * embedded data.
+ */
+ arc_buf_hdr_t *exists = NULL;
+ arc_buf_contents_t type = BP_GET_BUFC_TYPE(bp);
+ hdr = arc_hdr_alloc(spa_load_guid(spa), psize, lsize,
+ BP_IS_PROTECTED(bp), BP_GET_COMPRESS(bp), 0, type,
+ encrypted_read);
+
+ if (!embedded_bp) {
+ hdr->b_dva = *BP_IDENTITY(bp);
+ hdr->b_birth = BP_PHYSICAL_BIRTH(bp);
+ exists = buf_hash_insert(hdr, &hash_lock);
+ }
+ if (exists != NULL) {
+ /* somebody beat us to the hash insert */
+ mutex_exit(hash_lock);
+ buf_discard_identity(hdr);
+ arc_hdr_destroy(hdr);
+ goto top; /* restart the IO request */
+ }
+ } else {
+ /*
+ * This block is in the ghost cache or encrypted data
+ * was requested and we didn't have it. If it was
+ * L2-only (and thus didn't have an L1 hdr),
+ * we realloc the header to add an L1 hdr.
+ */
+ if (!HDR_HAS_L1HDR(hdr)) {
+ hdr = arc_hdr_realloc(hdr, hdr_l2only_cache,
+ hdr_full_cache);
+ }
+
+ if (GHOST_STATE(hdr->b_l1hdr.b_state)) {
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ ASSERT0(zfs_refcount_count(
+ &hdr->b_l1hdr.b_refcnt));
+ ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
+ ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
+ } else if (HDR_IO_IN_PROGRESS(hdr)) {
+ /*
+ * If this header already had an IO in progress
+ * and we are performing another IO to fetch
+ * encrypted data we must wait until the first
+ * IO completes so as not to confuse
+ * arc_read_done(). This should be very rare
+ * and so the performance impact shouldn't
+ * matter.
+ */
+ cv_wait(&hdr->b_l1hdr.b_cv, hash_lock);
+ mutex_exit(hash_lock);
+ goto top;
+ }
+
+ /*
+ * This is a delicate dance that we play here.
+ * This hdr might be in the ghost list so we access
+ * it to move it out of the ghost list before we
+ * initiate the read. If it's a prefetch then
+ * it won't have a callback so we'll remove the
+ * reference that arc_buf_alloc_impl() created. We
+ * do this after we've called arc_access() to
+ * avoid hitting an assert in remove_reference().
+ */
+ arc_adapt(arc_hdr_size(hdr), hdr->b_l1hdr.b_state);
+ arc_access(hdr, hash_lock);
+ arc_hdr_alloc_abd(hdr, alloc_flags);
+ }
+
+ if (encrypted_read) {
+ ASSERT(HDR_HAS_RABD(hdr));
+ size = HDR_GET_PSIZE(hdr);
+ hdr_abd = hdr->b_crypt_hdr.b_rabd;
+ zio_flags |= ZIO_FLAG_RAW;
+ } else {
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+ size = arc_hdr_size(hdr);
+ hdr_abd = hdr->b_l1hdr.b_pabd;
+
+ if (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF) {
+ zio_flags |= ZIO_FLAG_RAW_COMPRESS;
+ }
+
+ /*
+ * For authenticated bp's, we do not ask the ZIO layer
+ * to authenticate them since this will cause the entire
+ * IO to fail if the key isn't loaded. Instead, we
+ * defer authentication until arc_buf_fill(), which will
+ * verify the data when the key is available.
+ */
+ if (BP_IS_AUTHENTICATED(bp))
+ zio_flags |= ZIO_FLAG_RAW_ENCRYPT;
+ }
+
+ if (*arc_flags & ARC_FLAG_PREFETCH &&
+ zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt))
+ arc_hdr_set_flags(hdr, ARC_FLAG_PREFETCH);
+ if (*arc_flags & ARC_FLAG_PRESCIENT_PREFETCH)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PRESCIENT_PREFETCH);
+ if (*arc_flags & ARC_FLAG_L2CACHE)
+ arc_hdr_set_flags(hdr, ARC_FLAG_L2CACHE);
+ if (BP_IS_AUTHENTICATED(bp))
+ arc_hdr_set_flags(hdr, ARC_FLAG_NOAUTH);
+ if (BP_GET_LEVEL(bp) > 0)
+ arc_hdr_set_flags(hdr, ARC_FLAG_INDIRECT);
+ if (*arc_flags & ARC_FLAG_PREDICTIVE_PREFETCH)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PREDICTIVE_PREFETCH);
+ ASSERT(!GHOST_STATE(hdr->b_l1hdr.b_state));
+
+ acb = kmem_zalloc(sizeof (arc_callback_t), KM_SLEEP);
+ acb->acb_done = done;
+ acb->acb_private = private;
+ acb->acb_compressed = compressed_read;
+ acb->acb_encrypted = encrypted_read;
+ acb->acb_noauth = noauth_read;
+ acb->acb_zb = *zb;
+
+ ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
+ hdr->b_l1hdr.b_acb = acb;
+ arc_hdr_set_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
+
+ if (HDR_HAS_L2HDR(hdr) &&
+ (vd = hdr->b_l2hdr.b_dev->l2ad_vdev) != NULL) {
+ devw = hdr->b_l2hdr.b_dev->l2ad_writing;
+ addr = hdr->b_l2hdr.b_daddr;
+ /*
+ * Lock out L2ARC device removal.
+ */
+ if (vdev_is_dead(vd) ||
+ !spa_config_tryenter(spa, SCL_L2ARC, vd, RW_READER))
+ vd = NULL;
+ }
+
+ /*
+ * We count both async reads and scrub IOs as asynchronous so
+ * that both can be upgraded in the event of a cache hit while
+ * the read IO is still in-flight.
+ */
+ if (priority == ZIO_PRIORITY_ASYNC_READ ||
+ priority == ZIO_PRIORITY_SCRUB)
+ arc_hdr_set_flags(hdr, ARC_FLAG_PRIO_ASYNC_READ);
+ else
+ arc_hdr_clear_flags(hdr, ARC_FLAG_PRIO_ASYNC_READ);
+
+ /*
+ * At this point, we have a level 1 cache miss or a blkptr
+ * with embedded data. Try again in L2ARC if possible.
+ */
+ ASSERT3U(HDR_GET_LSIZE(hdr), ==, lsize);
+
+ /*
+ * Skip ARC stat bump for block pointers with embedded
+ * data. The data are read from the blkptr itself via
+ * decode_embedded_bp_compressed().
+ */
+ if (!embedded_bp) {
+ DTRACE_PROBE4(arc__miss, arc_buf_hdr_t *, hdr,
+ blkptr_t *, bp, uint64_t, lsize,
+ zbookmark_phys_t *, zb);
+ ARCSTAT_BUMP(arcstat_misses);
+ ARCSTAT_CONDSTAT(!HDR_PREFETCH(hdr),
+ demand, prefetch, !HDR_ISTYPE_METADATA(hdr), data,
+ metadata, misses);
+ }
+
+ if (vd != NULL && l2arc_ndev != 0 && !(l2arc_norw && devw)) {
+ /*
+ * Read from the L2ARC if the following are true:
+ * 1. The L2ARC vdev was previously cached.
+ * 2. This buffer still has L2ARC metadata.
+ * 3. This buffer isn't currently writing to the L2ARC.
+ * 4. The L2ARC entry wasn't evicted, which may
+ * also have invalidated the vdev.
+ * 5. This isn't prefetch and l2arc_noprefetch is set.
+ */
+ if (HDR_HAS_L2HDR(hdr) &&
+ !HDR_L2_WRITING(hdr) && !HDR_L2_EVICTED(hdr) &&
+ !(l2arc_noprefetch && HDR_PREFETCH(hdr))) {
+ l2arc_read_callback_t *cb;
+ abd_t *abd;
+ uint64_t asize;
+
+ DTRACE_PROBE1(l2arc__hit, arc_buf_hdr_t *, hdr);
+ ARCSTAT_BUMP(arcstat_l2_hits);
+ atomic_inc_32(&hdr->b_l2hdr.b_hits);
+
+ cb = kmem_zalloc(sizeof (l2arc_read_callback_t),
+ KM_SLEEP);
+ cb->l2rcb_hdr = hdr;
+ cb->l2rcb_bp = *bp;
+ cb->l2rcb_zb = *zb;
+ cb->l2rcb_flags = zio_flags;
+
+ /*
+ * When Compressed ARC is disabled, but the
+ * L2ARC block is compressed, arc_hdr_size()
+ * will have returned LSIZE rather than PSIZE.
+ */
+ if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
+ !HDR_COMPRESSION_ENABLED(hdr) &&
+ HDR_GET_PSIZE(hdr) != 0) {
+ size = HDR_GET_PSIZE(hdr);
+ }
+
+ asize = vdev_psize_to_asize(vd, size);
+ if (asize != size) {
+ abd = abd_alloc_for_io(asize,
+ HDR_ISTYPE_METADATA(hdr));
+ cb->l2rcb_abd = abd;
+ } else {
+ abd = hdr_abd;
+ }
+
+ ASSERT(addr >= VDEV_LABEL_START_SIZE &&
+ addr + asize <= vd->vdev_psize -
+ VDEV_LABEL_END_SIZE);
+
+ /*
+ * l2arc read. The SCL_L2ARC lock will be
+ * released by l2arc_read_done().
+ * Issue a null zio if the underlying buffer
+ * was squashed to zero size by compression.
+ */
+ ASSERT3U(arc_hdr_get_compress(hdr), !=,
+ ZIO_COMPRESS_EMPTY);
+ rzio = zio_read_phys(pio, vd, addr,
+ asize, abd,
+ ZIO_CHECKSUM_OFF,
+ l2arc_read_done, cb, priority,
+ zio_flags | ZIO_FLAG_DONT_CACHE |
+ ZIO_FLAG_CANFAIL |
+ ZIO_FLAG_DONT_PROPAGATE |
+ ZIO_FLAG_DONT_RETRY, B_FALSE);
+ acb->acb_zio_head = rzio;
+
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+
+ DTRACE_PROBE2(l2arc__read, vdev_t *, vd,
+ zio_t *, rzio);
+ ARCSTAT_INCR(arcstat_l2_read_bytes,
+ HDR_GET_PSIZE(hdr));
+
+ if (*arc_flags & ARC_FLAG_NOWAIT) {
+ zio_nowait(rzio);
+ goto out;
+ }
+
+ ASSERT(*arc_flags & ARC_FLAG_WAIT);
+ if (zio_wait(rzio) == 0)
+ goto out;
+
+ /* l2arc read error; goto zio_read() */
+ if (hash_lock != NULL)
+ mutex_enter(hash_lock);
+ } else {
+ DTRACE_PROBE1(l2arc__miss,
+ arc_buf_hdr_t *, hdr);
+ ARCSTAT_BUMP(arcstat_l2_misses);
+ if (HDR_L2_WRITING(hdr))
+ ARCSTAT_BUMP(arcstat_l2_rw_clash);
+ spa_config_exit(spa, SCL_L2ARC, vd);
+ }
+ } else {
+ if (vd != NULL)
+ spa_config_exit(spa, SCL_L2ARC, vd);
+ /*
+ * Skip ARC stat bump for block pointers with
+ * embedded data. The data are read from the blkptr
+ * itself via decode_embedded_bp_compressed().
+ */
+ if (l2arc_ndev != 0 && !embedded_bp) {
+ DTRACE_PROBE1(l2arc__miss,
+ arc_buf_hdr_t *, hdr);
+ ARCSTAT_BUMP(arcstat_l2_misses);
+ }
+ }
+
+ rzio = zio_read(pio, spa, bp, hdr_abd, size,
+ arc_read_done, hdr, priority, zio_flags, zb);
+ acb->acb_zio_head = rzio;
+
+ if (hash_lock != NULL)
+ mutex_exit(hash_lock);
+
+ if (*arc_flags & ARC_FLAG_WAIT) {
+ rc = zio_wait(rzio);
+ goto out;
+ }
+
+ ASSERT(*arc_flags & ARC_FLAG_NOWAIT);
+ zio_nowait(rzio);
+ }
+
+out:
+ /* embedded bps don't actually go to disk */
+ if (!embedded_bp)
+ spa_read_history_add(spa, zb, *arc_flags);
+ spl_fstrans_unmark(cookie);
+ return (rc);
+}
+
+arc_prune_t *
+arc_add_prune_callback(arc_prune_func_t *func, void *private)
+{
+ arc_prune_t *p;
+
+ p = kmem_alloc(sizeof (*p), KM_SLEEP);
+ p->p_pfunc = func;
+ p->p_private = private;
+ list_link_init(&p->p_node);
+ zfs_refcount_create(&p->p_refcnt);
+
+ mutex_enter(&arc_prune_mtx);
+ zfs_refcount_add(&p->p_refcnt, &arc_prune_list);
+ list_insert_head(&arc_prune_list, p);
+ mutex_exit(&arc_prune_mtx);
+
+ return (p);
+}
+
+void
+arc_remove_prune_callback(arc_prune_t *p)
+{
+ boolean_t wait = B_FALSE;
+ mutex_enter(&arc_prune_mtx);
+ list_remove(&arc_prune_list, p);
+ if (zfs_refcount_remove(&p->p_refcnt, &arc_prune_list) > 0)
+ wait = B_TRUE;
+ mutex_exit(&arc_prune_mtx);
+
+ /* wait for arc_prune_task to finish */
+ if (wait)
+ taskq_wait_outstanding(arc_prune_taskq, 0);
+ ASSERT0(zfs_refcount_count(&p->p_refcnt));
+ zfs_refcount_destroy(&p->p_refcnt);
+ kmem_free(p, sizeof (*p));
+}
+
+/*
+ * Notify the arc that a block was freed, and thus will never be used again.
+ */
+void
+arc_freed(spa_t *spa, const blkptr_t *bp)
+{
+ arc_buf_hdr_t *hdr;
+ kmutex_t *hash_lock;
+ uint64_t guid = spa_load_guid(spa);
+
+ ASSERT(!BP_IS_EMBEDDED(bp));
+
+ hdr = buf_hash_find(guid, bp, &hash_lock);
+ if (hdr == NULL)
+ return;
+
+ /*
+ * We might be trying to free a block that is still doing I/O
+ * (i.e. prefetch) or has a reference (i.e. a dedup-ed,
+ * dmu_sync-ed block). If this block is being prefetched, then it
+ * would still have the ARC_FLAG_IO_IN_PROGRESS flag set on the hdr
+ * until the I/O completes. A block may also have a reference if it is
+ * part of a dedup-ed, dmu_synced write. The dmu_sync() function would
+ * have written the new block to its final resting place on disk but
+ * without the dedup flag set. This would have left the hdr in the MRU
+ * state and discoverable. When the txg finally syncs it detects that
+ * the block was overridden in open context and issues an override I/O.
+ * Since this is a dedup block, the override I/O will determine if the
+ * block is already in the DDT. If so, then it will replace the io_bp
+ * with the bp from the DDT and allow the I/O to finish. When the I/O
+ * reaches the done callback, dbuf_write_override_done, it will
+ * check to see if the io_bp and io_bp_override are identical.
+ * If they are not, then it indicates that the bp was replaced with
+ * the bp in the DDT and the override bp is freed. This allows
+ * us to arrive here with a reference on a block that is being
+ * freed. So if we have an I/O in progress, or a reference to
+ * this hdr, then we don't destroy the hdr.
+ */
+ if (!HDR_HAS_L1HDR(hdr) || (!HDR_IO_IN_PROGRESS(hdr) &&
+ zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt))) {
+ arc_change_state(arc_anon, hdr, hash_lock);
+ arc_hdr_destroy(hdr);
+ mutex_exit(hash_lock);
+ } else {
+ mutex_exit(hash_lock);
+ }
+
+}
+
+/*
+ * Release this buffer from the cache, making it an anonymous buffer. This
+ * must be done after a read and prior to modifying the buffer contents.
+ * If the buffer has more than one reference, we must make
+ * a new hdr for the buffer.
+ */
+void
+arc_release(arc_buf_t *buf, void *tag)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ /*
+ * It would be nice to assert that if its DMU metadata (level >
+ * 0 || it's the dnode file), then it must be syncing context.
+ * But we don't know that information at this level.
+ */
+
+ mutex_enter(&buf->b_evict_lock);
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ /*
+ * We don't grab the hash lock prior to this check, because if
+ * the buffer's header is in the arc_anon state, it won't be
+ * linked into the hash table.
+ */
+ if (hdr->b_l1hdr.b_state == arc_anon) {
+ mutex_exit(&buf->b_evict_lock);
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ ASSERT(!HDR_IN_HASH_TABLE(hdr));
+ ASSERT(!HDR_HAS_L2HDR(hdr));
+ ASSERT(HDR_EMPTY(hdr));
+
+ ASSERT3U(hdr->b_l1hdr.b_bufcnt, ==, 1);
+ ASSERT3S(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt), ==, 1);
+ ASSERT(!list_link_active(&hdr->b_l1hdr.b_arc_node));
+
+ hdr->b_l1hdr.b_arc_access = 0;
+
+ /*
+ * If the buf is being overridden then it may already
+ * have a hdr that is not empty.
+ */
+ buf_discard_identity(hdr);
+ arc_buf_thaw(buf);
+
+ return;
+ }
+
+ kmutex_t *hash_lock = HDR_LOCK(hdr);
+ mutex_enter(hash_lock);
+
+ /*
+ * This assignment is only valid as long as the hash_lock is
+ * held, we must be careful not to reference state or the
+ * b_state field after dropping the lock.
+ */
+ arc_state_t *state = hdr->b_l1hdr.b_state;
+ ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
+ ASSERT3P(state, !=, arc_anon);
+
+ /* this buffer is not on any list */
+ ASSERT3S(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt), >, 0);
+
+ if (HDR_HAS_L2HDR(hdr)) {
+ mutex_enter(&hdr->b_l2hdr.b_dev->l2ad_mtx);
+
+ /*
+ * We have to recheck this conditional again now that
+ * we're holding the l2ad_mtx to prevent a race with
+ * another thread which might be concurrently calling
+ * l2arc_evict(). In that case, l2arc_evict() might have
+ * destroyed the header's L2 portion as we were waiting
+ * to acquire the l2ad_mtx.
+ */
+ if (HDR_HAS_L2HDR(hdr))
+ arc_hdr_l2hdr_destroy(hdr);
+
+ mutex_exit(&hdr->b_l2hdr.b_dev->l2ad_mtx);
+ }
+
+ /*
+ * Do we have more than one buf?
+ */
+ if (hdr->b_l1hdr.b_bufcnt > 1) {
+ arc_buf_hdr_t *nhdr;
+ uint64_t spa = hdr->b_spa;
+ uint64_t psize = HDR_GET_PSIZE(hdr);
+ uint64_t lsize = HDR_GET_LSIZE(hdr);
+ boolean_t protected = HDR_PROTECTED(hdr);
+ enum zio_compress compress = arc_hdr_get_compress(hdr);
+ arc_buf_contents_t type = arc_buf_type(hdr);
+ VERIFY3U(hdr->b_type, ==, type);
+
+ ASSERT(hdr->b_l1hdr.b_buf != buf || buf->b_next != NULL);
+ (void) remove_reference(hdr, hash_lock, tag);
+
+ if (arc_buf_is_shared(buf) && !ARC_BUF_COMPRESSED(buf)) {
+ ASSERT3P(hdr->b_l1hdr.b_buf, !=, buf);
+ ASSERT(ARC_BUF_LAST(buf));
+ }
+
+ /*
+ * Pull the data off of this hdr and attach it to
+ * a new anonymous hdr. Also find the last buffer
+ * in the hdr's buffer list.
+ */
+ arc_buf_t *lastbuf = arc_buf_remove(hdr, buf);
+ ASSERT3P(lastbuf, !=, NULL);
+
+ /*
+ * If the current arc_buf_t and the hdr are sharing their data
+ * buffer, then we must stop sharing that block.
+ */
+ if (arc_buf_is_shared(buf)) {
+ ASSERT3P(hdr->b_l1hdr.b_buf, !=, buf);
+ VERIFY(!arc_buf_is_shared(lastbuf));
+
+ /*
+ * First, sever the block sharing relationship between
+ * buf and the arc_buf_hdr_t.
+ */
+ arc_unshare_buf(hdr, buf);
+
+ /*
+ * Now we need to recreate the hdr's b_pabd. Since we
+ * have lastbuf handy, we try to share with it, but if
+ * we can't then we allocate a new b_pabd and copy the
+ * data from buf into it.
+ */
+ if (arc_can_share(hdr, lastbuf)) {
+ arc_share_buf(hdr, lastbuf);
+ } else {
+ arc_hdr_alloc_abd(hdr, ARC_HDR_DO_ADAPT);
+ abd_copy_from_buf(hdr->b_l1hdr.b_pabd,
+ buf->b_data, psize);
+ }
+ VERIFY3P(lastbuf->b_data, !=, NULL);
+ } else if (HDR_SHARED_DATA(hdr)) {
+ /*
+ * Uncompressed shared buffers are always at the end
+ * of the list. Compressed buffers don't have the
+ * same requirements. This makes it hard to
+ * simply assert that the lastbuf is shared so
+ * we rely on the hdr's compression flags to determine
+ * if we have a compressed, shared buffer.
+ */
+ ASSERT(arc_buf_is_shared(lastbuf) ||
+ arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF);
+ ASSERT(!ARC_BUF_SHARED(buf));
+ }
+
+ ASSERT(hdr->b_l1hdr.b_pabd != NULL || HDR_HAS_RABD(hdr));
+ ASSERT3P(state, !=, arc_l2c_only);
+
+ (void) zfs_refcount_remove_many(&state->arcs_size,
+ arc_buf_size(buf), buf);
+
+ if (zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt)) {
+ ASSERT3P(state, !=, arc_l2c_only);
+ (void) zfs_refcount_remove_many(
+ &state->arcs_esize[type],
+ arc_buf_size(buf), buf);
+ }
+
+ hdr->b_l1hdr.b_bufcnt -= 1;
+ if (ARC_BUF_ENCRYPTED(buf))
+ hdr->b_crypt_hdr.b_ebufcnt -= 1;
+
+ arc_cksum_verify(buf);
+ arc_buf_unwatch(buf);
+
+ /* if this is the last uncompressed buf free the checksum */
+ if (!arc_hdr_has_uncompressed_buf(hdr))
+ arc_cksum_free(hdr);
+
+ mutex_exit(hash_lock);
+
+ /*
+ * Allocate a new hdr. The new hdr will contain a b_pabd
+ * buffer which will be freed in arc_write().
+ */
+ nhdr = arc_hdr_alloc(spa, psize, lsize, protected,
+ compress, hdr->b_complevel, type, HDR_HAS_RABD(hdr));
+ ASSERT3P(nhdr->b_l1hdr.b_buf, ==, NULL);
+ ASSERT0(nhdr->b_l1hdr.b_bufcnt);
+ ASSERT0(zfs_refcount_count(&nhdr->b_l1hdr.b_refcnt));
+ VERIFY3U(nhdr->b_type, ==, type);
+ ASSERT(!HDR_SHARED_DATA(nhdr));
+
+ nhdr->b_l1hdr.b_buf = buf;
+ nhdr->b_l1hdr.b_bufcnt = 1;
+ if (ARC_BUF_ENCRYPTED(buf))
+ nhdr->b_crypt_hdr.b_ebufcnt = 1;
+ nhdr->b_l1hdr.b_mru_hits = 0;
+ nhdr->b_l1hdr.b_mru_ghost_hits = 0;
+ nhdr->b_l1hdr.b_mfu_hits = 0;
+ nhdr->b_l1hdr.b_mfu_ghost_hits = 0;
+ nhdr->b_l1hdr.b_l2_hits = 0;
+ (void) zfs_refcount_add(&nhdr->b_l1hdr.b_refcnt, tag);
+ buf->b_hdr = nhdr;
+
+ mutex_exit(&buf->b_evict_lock);
+ (void) zfs_refcount_add_many(&arc_anon->arcs_size,
+ arc_buf_size(buf), buf);
+ } else {
+ mutex_exit(&buf->b_evict_lock);
+ ASSERT(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt) == 1);
+ /* protected by hash lock, or hdr is on arc_anon */
+ ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ hdr->b_l1hdr.b_mru_hits = 0;
+ hdr->b_l1hdr.b_mru_ghost_hits = 0;
+ hdr->b_l1hdr.b_mfu_hits = 0;
+ hdr->b_l1hdr.b_mfu_ghost_hits = 0;
+ hdr->b_l1hdr.b_l2_hits = 0;
+ arc_change_state(arc_anon, hdr, hash_lock);
+ hdr->b_l1hdr.b_arc_access = 0;
+
+ mutex_exit(hash_lock);
+ buf_discard_identity(hdr);
+ arc_buf_thaw(buf);
+ }
+}
+
+int
+arc_released(arc_buf_t *buf)
+{
+ int released;
+
+ mutex_enter(&buf->b_evict_lock);
+ released = (buf->b_data != NULL &&
+ buf->b_hdr->b_l1hdr.b_state == arc_anon);
+ mutex_exit(&buf->b_evict_lock);
+ return (released);
+}
+
+#ifdef ZFS_DEBUG
+int
+arc_referenced(arc_buf_t *buf)
+{
+ int referenced;
+
+ mutex_enter(&buf->b_evict_lock);
+ referenced = (zfs_refcount_count(&buf->b_hdr->b_l1hdr.b_refcnt));
+ mutex_exit(&buf->b_evict_lock);
+ return (referenced);
+}
+#endif
+
+static void
+arc_write_ready(zio_t *zio)
+{
+ arc_write_callback_t *callback = zio->io_private;
+ arc_buf_t *buf = callback->awcb_buf;
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+ blkptr_t *bp = zio->io_bp;
+ uint64_t psize = BP_IS_HOLE(bp) ? 0 : BP_GET_PSIZE(bp);
+ fstrans_cookie_t cookie = spl_fstrans_mark();
+
+ ASSERT(HDR_HAS_L1HDR(hdr));
+ ASSERT(!zfs_refcount_is_zero(&buf->b_hdr->b_l1hdr.b_refcnt));
+ ASSERT(hdr->b_l1hdr.b_bufcnt > 0);
+
+ /*
+ * If we're reexecuting this zio because the pool suspended, then
+ * cleanup any state that was previously set the first time the
+ * callback was invoked.
+ */
+ if (zio->io_flags & ZIO_FLAG_REEXECUTED) {
+ arc_cksum_free(hdr);
+ arc_buf_unwatch(buf);
+ if (hdr->b_l1hdr.b_pabd != NULL) {
+ if (arc_buf_is_shared(buf)) {
+ arc_unshare_buf(hdr, buf);
+ } else {
+ arc_hdr_free_abd(hdr, B_FALSE);
+ }
+ }
+
+ if (HDR_HAS_RABD(hdr))
+ arc_hdr_free_abd(hdr, B_TRUE);
+ }
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+ ASSERT(!HDR_HAS_RABD(hdr));
+ ASSERT(!HDR_SHARED_DATA(hdr));
+ ASSERT(!arc_buf_is_shared(buf));
+
+ callback->awcb_ready(zio, buf, callback->awcb_private);
+
+ if (HDR_IO_IN_PROGRESS(hdr))
+ ASSERT(zio->io_flags & ZIO_FLAG_REEXECUTED);
+
+ arc_hdr_set_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
+
+ if (BP_IS_PROTECTED(bp) != !!HDR_PROTECTED(hdr))
+ hdr = arc_hdr_realloc_crypt(hdr, BP_IS_PROTECTED(bp));
+
+ if (BP_IS_PROTECTED(bp)) {
+ /* ZIL blocks are written through zio_rewrite */
+ ASSERT3U(BP_GET_TYPE(bp), !=, DMU_OT_INTENT_LOG);
+ ASSERT(HDR_PROTECTED(hdr));
+
+ if (BP_SHOULD_BYTESWAP(bp)) {
+ if (BP_GET_LEVEL(bp) > 0) {
+ hdr->b_l1hdr.b_byteswap = DMU_BSWAP_UINT64;
+ } else {
+ hdr->b_l1hdr.b_byteswap =
+ DMU_OT_BYTESWAP(BP_GET_TYPE(bp));
+ }
+ } else {
+ hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
+ }
+
+ hdr->b_crypt_hdr.b_ot = BP_GET_TYPE(bp);
+ hdr->b_crypt_hdr.b_dsobj = zio->io_bookmark.zb_objset;
+ zio_crypt_decode_params_bp(bp, hdr->b_crypt_hdr.b_salt,
+ hdr->b_crypt_hdr.b_iv);
+ zio_crypt_decode_mac_bp(bp, hdr->b_crypt_hdr.b_mac);
+ }
+
+ /*
+ * If this block was written for raw encryption but the zio layer
+ * ended up only authenticating it, adjust the buffer flags now.
+ */
+ if (BP_IS_AUTHENTICATED(bp) && ARC_BUF_ENCRYPTED(buf)) {
+ arc_hdr_set_flags(hdr, ARC_FLAG_NOAUTH);
+ buf->b_flags &= ~ARC_BUF_FLAG_ENCRYPTED;
+ if (BP_GET_COMPRESS(bp) == ZIO_COMPRESS_OFF)
+ buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
+ } else if (BP_IS_HOLE(bp) && ARC_BUF_ENCRYPTED(buf)) {
+ buf->b_flags &= ~ARC_BUF_FLAG_ENCRYPTED;
+ buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
+ }
+
+ /* this must be done after the buffer flags are adjusted */
+ arc_cksum_compute(buf);
+
+ enum zio_compress compress;
+ if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp)) {
+ compress = ZIO_COMPRESS_OFF;
+ } else {
+ ASSERT3U(HDR_GET_LSIZE(hdr), ==, BP_GET_LSIZE(bp));
+ compress = BP_GET_COMPRESS(bp);
+ }
+ HDR_SET_PSIZE(hdr, psize);
+ arc_hdr_set_compress(hdr, compress);
+ hdr->b_complevel = zio->io_prop.zp_complevel;
+
+ if (zio->io_error != 0 || psize == 0)
+ goto out;
+
+ /*
+ * Fill the hdr with data. If the buffer is encrypted we have no choice
+ * but to copy the data into b_radb. If the hdr is compressed, the data
+ * we want is available from the zio, otherwise we can take it from
+ * the buf.
+ *
+ * We might be able to share the buf's data with the hdr here. However,
+ * doing so would cause the ARC to be full of linear ABDs if we write a
+ * lot of shareable data. As a compromise, we check whether scattered
+ * ABDs are allowed, and assume that if they are then the user wants
+ * the ARC to be primarily filled with them regardless of the data being
+ * written. Therefore, if they're allowed then we allocate one and copy
+ * the data into it; otherwise, we share the data directly if we can.
+ */
+ if (ARC_BUF_ENCRYPTED(buf)) {
+ ASSERT3U(psize, >, 0);
+ ASSERT(ARC_BUF_COMPRESSED(buf));
+ arc_hdr_alloc_abd(hdr, ARC_HDR_DO_ADAPT|ARC_HDR_ALLOC_RDATA);
+ abd_copy(hdr->b_crypt_hdr.b_rabd, zio->io_abd, psize);
+ } else if (zfs_abd_scatter_enabled || !arc_can_share(hdr, buf)) {
+ /*
+ * Ideally, we would always copy the io_abd into b_pabd, but the
+ * user may have disabled compressed ARC, thus we must check the
+ * hdr's compression setting rather than the io_bp's.
+ */
+ if (BP_IS_ENCRYPTED(bp)) {
+ ASSERT3U(psize, >, 0);
+ arc_hdr_alloc_abd(hdr,
+ ARC_HDR_DO_ADAPT|ARC_HDR_ALLOC_RDATA);
+ abd_copy(hdr->b_crypt_hdr.b_rabd, zio->io_abd, psize);
+ } else if (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF &&
+ !ARC_BUF_COMPRESSED(buf)) {
+ ASSERT3U(psize, >, 0);
+ arc_hdr_alloc_abd(hdr, ARC_HDR_DO_ADAPT);
+ abd_copy(hdr->b_l1hdr.b_pabd, zio->io_abd, psize);
+ } else {
+ ASSERT3U(zio->io_orig_size, ==, arc_hdr_size(hdr));
+ arc_hdr_alloc_abd(hdr, ARC_HDR_DO_ADAPT);
+ abd_copy_from_buf(hdr->b_l1hdr.b_pabd, buf->b_data,
+ arc_buf_size(buf));
+ }
+ } else {
+ ASSERT3P(buf->b_data, ==, abd_to_buf(zio->io_orig_abd));
+ ASSERT3U(zio->io_orig_size, ==, arc_buf_size(buf));
+ ASSERT3U(hdr->b_l1hdr.b_bufcnt, ==, 1);
+
+ arc_share_buf(hdr, buf);
+ }
+
+out:
+ arc_hdr_verify(hdr, bp);
+ spl_fstrans_unmark(cookie);
+}
+
+static void
+arc_write_children_ready(zio_t *zio)
+{
+ arc_write_callback_t *callback = zio->io_private;
+ arc_buf_t *buf = callback->awcb_buf;
+
+ callback->awcb_children_ready(zio, buf, callback->awcb_private);
+}
+
+/*
+ * The SPA calls this callback for each physical write that happens on behalf
+ * of a logical write. See the comment in dbuf_write_physdone() for details.
+ */
+static void
+arc_write_physdone(zio_t *zio)
+{
+ arc_write_callback_t *cb = zio->io_private;
+ if (cb->awcb_physdone != NULL)
+ cb->awcb_physdone(zio, cb->awcb_buf, cb->awcb_private);
+}
+
+static void
+arc_write_done(zio_t *zio)
+{
+ arc_write_callback_t *callback = zio->io_private;
+ arc_buf_t *buf = callback->awcb_buf;
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
+
+ if (zio->io_error == 0) {
+ arc_hdr_verify(hdr, zio->io_bp);
+
+ if (BP_IS_HOLE(zio->io_bp) || BP_IS_EMBEDDED(zio->io_bp)) {
+ buf_discard_identity(hdr);
+ } else {
+ hdr->b_dva = *BP_IDENTITY(zio->io_bp);
+ hdr->b_birth = BP_PHYSICAL_BIRTH(zio->io_bp);
+ }
+ } else {
+ ASSERT(HDR_EMPTY(hdr));
+ }
+
+ /*
+ * If the block to be written was all-zero or compressed enough to be
+ * embedded in the BP, no write was performed so there will be no
+ * dva/birth/checksum. The buffer must therefore remain anonymous
+ * (and uncached).
+ */
+ if (!HDR_EMPTY(hdr)) {
+ arc_buf_hdr_t *exists;
+ kmutex_t *hash_lock;
+
+ ASSERT3U(zio->io_error, ==, 0);
+
+ arc_cksum_verify(buf);
+
+ exists = buf_hash_insert(hdr, &hash_lock);
+ if (exists != NULL) {
+ /*
+ * This can only happen if we overwrite for
+ * sync-to-convergence, because we remove
+ * buffers from the hash table when we arc_free().
+ */
+ if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
+ if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp))
+ panic("bad overwrite, hdr=%p exists=%p",
+ (void *)hdr, (void *)exists);
+ ASSERT(zfs_refcount_is_zero(
+ &exists->b_l1hdr.b_refcnt));
+ arc_change_state(arc_anon, exists, hash_lock);
+ arc_hdr_destroy(exists);
+ mutex_exit(hash_lock);
+ exists = buf_hash_insert(hdr, &hash_lock);
+ ASSERT3P(exists, ==, NULL);
+ } else if (zio->io_flags & ZIO_FLAG_NOPWRITE) {
+ /* nopwrite */
+ ASSERT(zio->io_prop.zp_nopwrite);
+ if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp))
+ panic("bad nopwrite, hdr=%p exists=%p",
+ (void *)hdr, (void *)exists);
+ } else {
+ /* Dedup */
+ ASSERT(hdr->b_l1hdr.b_bufcnt == 1);
+ ASSERT(hdr->b_l1hdr.b_state == arc_anon);
+ ASSERT(BP_GET_DEDUP(zio->io_bp));
+ ASSERT(BP_GET_LEVEL(zio->io_bp) == 0);
+ }
+ }
+ arc_hdr_clear_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
+ /* if it's not anon, we are doing a scrub */
+ if (exists == NULL && hdr->b_l1hdr.b_state == arc_anon)
+ arc_access(hdr, hash_lock);
+ mutex_exit(hash_lock);
+ } else {
+ arc_hdr_clear_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
+ }
+
+ ASSERT(!zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
+ callback->awcb_done(zio, buf, callback->awcb_private);
+
+ abd_put(zio->io_abd);
+ kmem_free(callback, sizeof (arc_write_callback_t));
+}
+
+zio_t *
+arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
+ blkptr_t *bp, arc_buf_t *buf, boolean_t l2arc,
+ const zio_prop_t *zp, arc_write_done_func_t *ready,
+ arc_write_done_func_t *children_ready, arc_write_done_func_t *physdone,
+ arc_write_done_func_t *done, void *private, zio_priority_t priority,
+ int zio_flags, const zbookmark_phys_t *zb)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+ arc_write_callback_t *callback;
+ zio_t *zio;
+ zio_prop_t localprop = *zp;
+
+ ASSERT3P(ready, !=, NULL);
+ ASSERT3P(done, !=, NULL);
+ ASSERT(!HDR_IO_ERROR(hdr));
+ ASSERT(!HDR_IO_IN_PROGRESS(hdr));
+ ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
+ ASSERT3U(hdr->b_l1hdr.b_bufcnt, >, 0);
+ if (l2arc)
+ arc_hdr_set_flags(hdr, ARC_FLAG_L2CACHE);
+
+ if (ARC_BUF_ENCRYPTED(buf)) {
+ ASSERT(ARC_BUF_COMPRESSED(buf));
+ localprop.zp_encrypt = B_TRUE;
+ localprop.zp_compress = HDR_GET_COMPRESS(hdr);
+ localprop.zp_complevel = hdr->b_complevel;
+ localprop.zp_byteorder =
+ (hdr->b_l1hdr.b_byteswap == DMU_BSWAP_NUMFUNCS) ?
+ ZFS_HOST_BYTEORDER : !ZFS_HOST_BYTEORDER;
+ bcopy(hdr->b_crypt_hdr.b_salt, localprop.zp_salt,
+ ZIO_DATA_SALT_LEN);
+ bcopy(hdr->b_crypt_hdr.b_iv, localprop.zp_iv,
+ ZIO_DATA_IV_LEN);
+ bcopy(hdr->b_crypt_hdr.b_mac, localprop.zp_mac,
+ ZIO_DATA_MAC_LEN);
+ if (DMU_OT_IS_ENCRYPTED(localprop.zp_type)) {
+ localprop.zp_nopwrite = B_FALSE;
+ localprop.zp_copies =
+ MIN(localprop.zp_copies, SPA_DVAS_PER_BP - 1);
+ }
+ zio_flags |= ZIO_FLAG_RAW;
+ } else if (ARC_BUF_COMPRESSED(buf)) {
+ ASSERT3U(HDR_GET_LSIZE(hdr), !=, arc_buf_size(buf));
+ localprop.zp_compress = HDR_GET_COMPRESS(hdr);
+ localprop.zp_complevel = hdr->b_complevel;
+ zio_flags |= ZIO_FLAG_RAW_COMPRESS;
+ }
+ callback = kmem_zalloc(sizeof (arc_write_callback_t), KM_SLEEP);
+ callback->awcb_ready = ready;
+ callback->awcb_children_ready = children_ready;
+ callback->awcb_physdone = physdone;
+ callback->awcb_done = done;
+ callback->awcb_private = private;
+ callback->awcb_buf = buf;
+
+ /*
+ * The hdr's b_pabd is now stale, free it now. A new data block
+ * will be allocated when the zio pipeline calls arc_write_ready().
+ */
+ if (hdr->b_l1hdr.b_pabd != NULL) {
+ /*
+ * If the buf is currently sharing the data block with
+ * the hdr then we need to break that relationship here.
+ * The hdr will remain with a NULL data pointer and the
+ * buf will take sole ownership of the block.
+ */
+ if (arc_buf_is_shared(buf)) {
+ arc_unshare_buf(hdr, buf);
+ } else {
+ arc_hdr_free_abd(hdr, B_FALSE);
+ }
+ VERIFY3P(buf->b_data, !=, NULL);
+ }
+
+ if (HDR_HAS_RABD(hdr))
+ arc_hdr_free_abd(hdr, B_TRUE);
+
+ if (!(zio_flags & ZIO_FLAG_RAW))
+ arc_hdr_set_compress(hdr, ZIO_COMPRESS_OFF);
+
+ ASSERT(!arc_buf_is_shared(buf));
+ ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
+
+ zio = zio_write(pio, spa, txg, bp,
+ abd_get_from_buf(buf->b_data, HDR_GET_LSIZE(hdr)),
+ HDR_GET_LSIZE(hdr), arc_buf_size(buf), &localprop, arc_write_ready,
+ (children_ready != NULL) ? arc_write_children_ready : NULL,
+ arc_write_physdone, arc_write_done, callback,
+ priority, zio_flags, zb);
+
+ return (zio);
+}
+
+void
+arc_tempreserve_clear(uint64_t reserve)
+{
+ atomic_add_64(&arc_tempreserve, -reserve);
+ ASSERT((int64_t)arc_tempreserve >= 0);
+}
+
+int
+arc_tempreserve_space(spa_t *spa, uint64_t reserve, uint64_t txg)
+{
+ int error;
+ uint64_t anon_size;
+
+ if (!arc_no_grow &&
+ reserve > arc_c/4 &&
+ reserve * 4 > (2ULL << SPA_MAXBLOCKSHIFT))
+ arc_c = MIN(arc_c_max, reserve * 4);
+
+ /*
+ * Throttle when the calculated memory footprint for the TXG
+ * exceeds the target ARC size.
+ */
+ if (reserve > arc_c) {
+ DMU_TX_STAT_BUMP(dmu_tx_memory_reserve);
+ return (SET_ERROR(ERESTART));
+ }
+
+ /*
+ * Don't count loaned bufs as in flight dirty data to prevent long
+ * network delays from blocking transactions that are ready to be
+ * assigned to a txg.
+ */
+
+ /* assert that it has not wrapped around */
+ ASSERT3S(atomic_add_64_nv(&arc_loaned_bytes, 0), >=, 0);
+
+ anon_size = MAX((int64_t)(zfs_refcount_count(&arc_anon->arcs_size) -
+ arc_loaned_bytes), 0);
+
+ /*
+ * Writes will, almost always, require additional memory allocations
+ * in order to compress/encrypt/etc the data. We therefore need to
+ * make sure that there is sufficient available memory for this.
+ */
+ error = arc_memory_throttle(spa, reserve, txg);
+ if (error != 0)
+ return (error);
+
+ /*
+ * Throttle writes when the amount of dirty data in the cache
+ * gets too large. We try to keep the cache less than half full
+ * of dirty blocks so that our sync times don't grow too large.
+ *
+ * In the case of one pool being built on another pool, we want
+ * to make sure we don't end up throttling the lower (backing)
+ * pool when the upper pool is the majority contributor to dirty
+ * data. To insure we make forward progress during throttling, we
+ * also check the current pool's net dirty data and only throttle
+ * if it exceeds zfs_arc_pool_dirty_percent of the anonymous dirty
+ * data in the cache.
+ *
+ * Note: if two requests come in concurrently, we might let them
+ * both succeed, when one of them should fail. Not a huge deal.
+ */
+ uint64_t total_dirty = reserve + arc_tempreserve + anon_size;
+ uint64_t spa_dirty_anon = spa_dirty_data(spa);
+
+ if (total_dirty > arc_c * zfs_arc_dirty_limit_percent / 100 &&
+ anon_size > arc_c * zfs_arc_anon_limit_percent / 100 &&
+ spa_dirty_anon > anon_size * zfs_arc_pool_dirty_percent / 100) {
+#ifdef ZFS_DEBUG
+ uint64_t meta_esize = zfs_refcount_count(
+ &arc_anon->arcs_esize[ARC_BUFC_METADATA]);
+ uint64_t data_esize =
+ zfs_refcount_count(&arc_anon->arcs_esize[ARC_BUFC_DATA]);
+ dprintf("failing, arc_tempreserve=%lluK anon_meta=%lluK "
+ "anon_data=%lluK tempreserve=%lluK arc_c=%lluK\n",
+ arc_tempreserve >> 10, meta_esize >> 10,
+ data_esize >> 10, reserve >> 10, arc_c >> 10);
+#endif
+ DMU_TX_STAT_BUMP(dmu_tx_dirty_throttle);
+ return (SET_ERROR(ERESTART));
+ }
+ atomic_add_64(&arc_tempreserve, reserve);
+ return (0);
+}
+
+static void
+arc_kstat_update_state(arc_state_t *state, kstat_named_t *size,
+ kstat_named_t *evict_data, kstat_named_t *evict_metadata)
+{
+ size->value.ui64 = zfs_refcount_count(&state->arcs_size);
+ evict_data->value.ui64 =
+ zfs_refcount_count(&state->arcs_esize[ARC_BUFC_DATA]);
+ evict_metadata->value.ui64 =
+ zfs_refcount_count(&state->arcs_esize[ARC_BUFC_METADATA]);
+}
+
+static int
+arc_kstat_update(kstat_t *ksp, int rw)
+{
+ arc_stats_t *as = ksp->ks_data;
+
+ if (rw == KSTAT_WRITE) {
+ return (SET_ERROR(EACCES));
+ } else {
+ arc_kstat_update_state(arc_anon,
+ &as->arcstat_anon_size,
+ &as->arcstat_anon_evictable_data,
+ &as->arcstat_anon_evictable_metadata);
+ arc_kstat_update_state(arc_mru,
+ &as->arcstat_mru_size,
+ &as->arcstat_mru_evictable_data,
+ &as->arcstat_mru_evictable_metadata);
+ arc_kstat_update_state(arc_mru_ghost,
+ &as->arcstat_mru_ghost_size,
+ &as->arcstat_mru_ghost_evictable_data,
+ &as->arcstat_mru_ghost_evictable_metadata);
+ arc_kstat_update_state(arc_mfu,
+ &as->arcstat_mfu_size,
+ &as->arcstat_mfu_evictable_data,
+ &as->arcstat_mfu_evictable_metadata);
+ arc_kstat_update_state(arc_mfu_ghost,
+ &as->arcstat_mfu_ghost_size,
+ &as->arcstat_mfu_ghost_evictable_data,
+ &as->arcstat_mfu_ghost_evictable_metadata);
+
+ ARCSTAT(arcstat_size) = aggsum_value(&arc_size);
+ ARCSTAT(arcstat_meta_used) = aggsum_value(&arc_meta_used);
+ ARCSTAT(arcstat_data_size) = aggsum_value(&astat_data_size);
+ ARCSTAT(arcstat_metadata_size) =
+ aggsum_value(&astat_metadata_size);
+ ARCSTAT(arcstat_hdr_size) = aggsum_value(&astat_hdr_size);
+ ARCSTAT(arcstat_l2_hdr_size) = aggsum_value(&astat_l2_hdr_size);
+ ARCSTAT(arcstat_dbuf_size) = aggsum_value(&astat_dbuf_size);
+#if defined(COMPAT_FREEBSD11)
+ ARCSTAT(arcstat_other_size) = aggsum_value(&astat_bonus_size) +
+ aggsum_value(&astat_dnode_size) +
+ aggsum_value(&astat_dbuf_size);
+#endif
+ ARCSTAT(arcstat_dnode_size) = aggsum_value(&astat_dnode_size);
+ ARCSTAT(arcstat_bonus_size) = aggsum_value(&astat_bonus_size);
+ ARCSTAT(arcstat_abd_chunk_waste_size) =
+ aggsum_value(&astat_abd_chunk_waste_size);
+
+ as->arcstat_memory_all_bytes.value.ui64 =
+ arc_all_memory();
+ as->arcstat_memory_free_bytes.value.ui64 =
+ arc_free_memory();
+ as->arcstat_memory_available_bytes.value.i64 =
+ arc_available_memory();
+ }
+
+ return (0);
+}
+
+/*
+ * This function *must* return indices evenly distributed between all
+ * sublists of the multilist. This is needed due to how the ARC eviction
+ * code is laid out; arc_evict_state() assumes ARC buffers are evenly
+ * distributed between all sublists and uses this assumption when
+ * deciding which sublist to evict from and how much to evict from it.
+ */
+static unsigned int
+arc_state_multilist_index_func(multilist_t *ml, void *obj)
+{
+ arc_buf_hdr_t *hdr = obj;
+
+ /*
+ * We rely on b_dva to generate evenly distributed index
+ * numbers using buf_hash below. So, as an added precaution,
+ * let's make sure we never add empty buffers to the arc lists.
+ */
+ ASSERT(!HDR_EMPTY(hdr));
+
+ /*
+ * The assumption here, is the hash value for a given
+ * arc_buf_hdr_t will remain constant throughout its lifetime
+ * (i.e. its b_spa, b_dva, and b_birth fields don't change).
+ * Thus, we don't need to store the header's sublist index
+ * on insertion, as this index can be recalculated on removal.
+ *
+ * Also, the low order bits of the hash value are thought to be
+ * distributed evenly. Otherwise, in the case that the multilist
+ * has a power of two number of sublists, each sublists' usage
+ * would not be evenly distributed.
+ */
+ return (buf_hash(hdr->b_spa, &hdr->b_dva, hdr->b_birth) %
+ multilist_get_num_sublists(ml));
+}
+
+#define WARN_IF_TUNING_IGNORED(tuning, value, do_warn) do { \
+ if ((do_warn) && (tuning) && ((tuning) != (value))) { \
+ cmn_err(CE_WARN, \
+ "ignoring tunable %s (using %llu instead)", \
+ (#tuning), (value)); \
+ } \
+} while (0)
+
+/*
+ * Called during module initialization and periodically thereafter to
+ * apply reasonable changes to the exposed performance tunings. Can also be
+ * called explicitly by param_set_arc_*() functions when ARC tunables are
+ * updated manually. Non-zero zfs_* values which differ from the currently set
+ * values will be applied.
+ */
+void
+arc_tuning_update(boolean_t verbose)
+{
+ uint64_t allmem = arc_all_memory();
+ unsigned long limit;
+
+ /* Valid range: 32M - <arc_c_max> */
+ if ((zfs_arc_min) && (zfs_arc_min != arc_c_min) &&
+ (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT) &&
+ (zfs_arc_min <= arc_c_max)) {
+ arc_c_min = zfs_arc_min;
+ arc_c = MAX(arc_c, arc_c_min);
+ }
+ WARN_IF_TUNING_IGNORED(zfs_arc_min, arc_c_min, verbose);
+
+ /* Valid range: 64M - <all physical memory> */
+ if ((zfs_arc_max) && (zfs_arc_max != arc_c_max) &&
+ (zfs_arc_max >= 64 << 20) && (zfs_arc_max < allmem) &&
+ (zfs_arc_max > arc_c_min)) {
+ arc_c_max = zfs_arc_max;
+ arc_c = MIN(arc_c, arc_c_max);
+ arc_p = (arc_c >> 1);
+ if (arc_meta_limit > arc_c_max)
+ arc_meta_limit = arc_c_max;
+ if (arc_dnode_size_limit > arc_meta_limit)
+ arc_dnode_size_limit = arc_meta_limit;
+ }
+ WARN_IF_TUNING_IGNORED(zfs_arc_max, arc_c_max, verbose);
+
+ /* Valid range: 16M - <arc_c_max> */
+ if ((zfs_arc_meta_min) && (zfs_arc_meta_min != arc_meta_min) &&
+ (zfs_arc_meta_min >= 1ULL << SPA_MAXBLOCKSHIFT) &&
+ (zfs_arc_meta_min <= arc_c_max)) {
+ arc_meta_min = zfs_arc_meta_min;
+ if (arc_meta_limit < arc_meta_min)
+ arc_meta_limit = arc_meta_min;
+ if (arc_dnode_size_limit < arc_meta_min)
+ arc_dnode_size_limit = arc_meta_min;
+ }
+ WARN_IF_TUNING_IGNORED(zfs_arc_meta_min, arc_meta_min, verbose);
+
+ /* Valid range: <arc_meta_min> - <arc_c_max> */
+ limit = zfs_arc_meta_limit ? zfs_arc_meta_limit :
+ MIN(zfs_arc_meta_limit_percent, 100) * arc_c_max / 100;
+ if ((limit != arc_meta_limit) &&
+ (limit >= arc_meta_min) &&
+ (limit <= arc_c_max))
+ arc_meta_limit = limit;
+ WARN_IF_TUNING_IGNORED(zfs_arc_meta_limit, arc_meta_limit, verbose);
+
+ /* Valid range: <arc_meta_min> - <arc_meta_limit> */
+ limit = zfs_arc_dnode_limit ? zfs_arc_dnode_limit :
+ MIN(zfs_arc_dnode_limit_percent, 100) * arc_meta_limit / 100;
+ if ((limit != arc_dnode_size_limit) &&
+ (limit >= arc_meta_min) &&
+ (limit <= arc_meta_limit))
+ arc_dnode_size_limit = limit;
+ WARN_IF_TUNING_IGNORED(zfs_arc_dnode_limit, arc_dnode_size_limit,
+ verbose);
+
+ /* Valid range: 1 - N */
+ if (zfs_arc_grow_retry)
+ arc_grow_retry = zfs_arc_grow_retry;
+
+ /* Valid range: 1 - N */
+ if (zfs_arc_shrink_shift) {
+ arc_shrink_shift = zfs_arc_shrink_shift;
+ arc_no_grow_shift = MIN(arc_no_grow_shift, arc_shrink_shift -1);
+ }
+
+ /* Valid range: 1 - N */
+ if (zfs_arc_p_min_shift)
+ arc_p_min_shift = zfs_arc_p_min_shift;
+
+ /* Valid range: 1 - N ms */
+ if (zfs_arc_min_prefetch_ms)
+ arc_min_prefetch_ms = zfs_arc_min_prefetch_ms;
+
+ /* Valid range: 1 - N ms */
+ if (zfs_arc_min_prescient_prefetch_ms) {
+ arc_min_prescient_prefetch_ms =
+ zfs_arc_min_prescient_prefetch_ms;
+ }
+
+ /* Valid range: 0 - 100 */
+ if ((zfs_arc_lotsfree_percent >= 0) &&
+ (zfs_arc_lotsfree_percent <= 100))
+ arc_lotsfree_percent = zfs_arc_lotsfree_percent;
+ WARN_IF_TUNING_IGNORED(zfs_arc_lotsfree_percent, arc_lotsfree_percent,
+ verbose);
+
+ /* Valid range: 0 - <all physical memory> */
+ if ((zfs_arc_sys_free) && (zfs_arc_sys_free != arc_sys_free))
+ arc_sys_free = MIN(MAX(zfs_arc_sys_free, 0), allmem);
+ WARN_IF_TUNING_IGNORED(zfs_arc_sys_free, arc_sys_free, verbose);
+}
+
+static void
+arc_state_init(void)
+{
+ arc_anon = &ARC_anon;
+ arc_mru = &ARC_mru;
+ arc_mru_ghost = &ARC_mru_ghost;
+ arc_mfu = &ARC_mfu;
+ arc_mfu_ghost = &ARC_mfu_ghost;
+ arc_l2c_only = &ARC_l2c_only;
+
+ arc_mru->arcs_list[ARC_BUFC_METADATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mru->arcs_list[ARC_BUFC_DATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mru_ghost->arcs_list[ARC_BUFC_METADATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mru_ghost->arcs_list[ARC_BUFC_DATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mfu->arcs_list[ARC_BUFC_METADATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mfu->arcs_list[ARC_BUFC_DATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_mfu_ghost->arcs_list[ARC_BUFC_DATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_l2c_only->arcs_list[ARC_BUFC_METADATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+ arc_l2c_only->arcs_list[ARC_BUFC_DATA] =
+ multilist_create(sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node),
+ arc_state_multilist_index_func);
+
+ zfs_refcount_create(&arc_anon->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_create(&arc_anon->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_create(&arc_mru->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_create(&arc_mru->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_create(&arc_mru_ghost->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_create(&arc_mru_ghost->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_create(&arc_mfu->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_create(&arc_mfu->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_create(&arc_mfu_ghost->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_create(&arc_mfu_ghost->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_create(&arc_l2c_only->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_create(&arc_l2c_only->arcs_esize[ARC_BUFC_DATA]);
+
+ zfs_refcount_create(&arc_anon->arcs_size);
+ zfs_refcount_create(&arc_mru->arcs_size);
+ zfs_refcount_create(&arc_mru_ghost->arcs_size);
+ zfs_refcount_create(&arc_mfu->arcs_size);
+ zfs_refcount_create(&arc_mfu_ghost->arcs_size);
+ zfs_refcount_create(&arc_l2c_only->arcs_size);
+
+ aggsum_init(&arc_meta_used, 0);
+ aggsum_init(&arc_size, 0);
+ aggsum_init(&astat_data_size, 0);
+ aggsum_init(&astat_metadata_size, 0);
+ aggsum_init(&astat_hdr_size, 0);
+ aggsum_init(&astat_l2_hdr_size, 0);
+ aggsum_init(&astat_bonus_size, 0);
+ aggsum_init(&astat_dnode_size, 0);
+ aggsum_init(&astat_dbuf_size, 0);
+ aggsum_init(&astat_abd_chunk_waste_size, 0);
+
+ arc_anon->arcs_state = ARC_STATE_ANON;
+ arc_mru->arcs_state = ARC_STATE_MRU;
+ arc_mru_ghost->arcs_state = ARC_STATE_MRU_GHOST;
+ arc_mfu->arcs_state = ARC_STATE_MFU;
+ arc_mfu_ghost->arcs_state = ARC_STATE_MFU_GHOST;
+ arc_l2c_only->arcs_state = ARC_STATE_L2C_ONLY;
+}
+
+static void
+arc_state_fini(void)
+{
+ zfs_refcount_destroy(&arc_anon->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_destroy(&arc_anon->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_destroy(&arc_mru->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_destroy(&arc_mru->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_destroy(&arc_mru_ghost->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_destroy(&arc_mru_ghost->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_destroy(&arc_mfu->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_destroy(&arc_mfu->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_destroy(&arc_mfu_ghost->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_destroy(&arc_mfu_ghost->arcs_esize[ARC_BUFC_DATA]);
+ zfs_refcount_destroy(&arc_l2c_only->arcs_esize[ARC_BUFC_METADATA]);
+ zfs_refcount_destroy(&arc_l2c_only->arcs_esize[ARC_BUFC_DATA]);
+
+ zfs_refcount_destroy(&arc_anon->arcs_size);
+ zfs_refcount_destroy(&arc_mru->arcs_size);
+ zfs_refcount_destroy(&arc_mru_ghost->arcs_size);
+ zfs_refcount_destroy(&arc_mfu->arcs_size);
+ zfs_refcount_destroy(&arc_mfu_ghost->arcs_size);
+ zfs_refcount_destroy(&arc_l2c_only->arcs_size);
+
+ multilist_destroy(arc_mru->arcs_list[ARC_BUFC_METADATA]);
+ multilist_destroy(arc_mru_ghost->arcs_list[ARC_BUFC_METADATA]);
+ multilist_destroy(arc_mfu->arcs_list[ARC_BUFC_METADATA]);
+ multilist_destroy(arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA]);
+ multilist_destroy(arc_mru->arcs_list[ARC_BUFC_DATA]);
+ multilist_destroy(arc_mru_ghost->arcs_list[ARC_BUFC_DATA]);
+ multilist_destroy(arc_mfu->arcs_list[ARC_BUFC_DATA]);
+ multilist_destroy(arc_mfu_ghost->arcs_list[ARC_BUFC_DATA]);
+ multilist_destroy(arc_l2c_only->arcs_list[ARC_BUFC_METADATA]);
+ multilist_destroy(arc_l2c_only->arcs_list[ARC_BUFC_DATA]);
+
+ aggsum_fini(&arc_meta_used);
+ aggsum_fini(&arc_size);
+ aggsum_fini(&astat_data_size);
+ aggsum_fini(&astat_metadata_size);
+ aggsum_fini(&astat_hdr_size);
+ aggsum_fini(&astat_l2_hdr_size);
+ aggsum_fini(&astat_bonus_size);
+ aggsum_fini(&astat_dnode_size);
+ aggsum_fini(&astat_dbuf_size);
+ aggsum_fini(&astat_abd_chunk_waste_size);
+}
+
+uint64_t
+arc_target_bytes(void)
+{
+ return (arc_c);
+}
+
+void
+arc_init(void)
+{
+ uint64_t percent, allmem = arc_all_memory();
+ mutex_init(&arc_evict_lock, NULL, MUTEX_DEFAULT, NULL);
+ list_create(&arc_evict_waiters, sizeof (arc_evict_waiter_t),
+ offsetof(arc_evict_waiter_t, aew_node));
+
+ arc_min_prefetch_ms = 1000;
+ arc_min_prescient_prefetch_ms = 6000;
+
+#if defined(_KERNEL)
+ arc_lowmem_init();
+#endif
+
+ /* Set min cache to 1/32 of all memory, or 32MB, whichever is more. */
+ arc_c_min = MAX(allmem / 32, 2ULL << SPA_MAXBLOCKSHIFT);
+
+ /* How to set default max varies by platform. */
+ arc_c_max = arc_default_max(arc_c_min, allmem);
+
+#ifndef _KERNEL
+ /*
+ * In userland, there's only the memory pressure that we artificially
+ * create (see arc_available_memory()). Don't let arc_c get too
+ * small, because it can cause transactions to be larger than
+ * arc_c, causing arc_tempreserve_space() to fail.
+ */
+ arc_c_min = MAX(arc_c_max / 2, 2ULL << SPA_MAXBLOCKSHIFT);
+#endif
+
+ arc_c = arc_c_min;
+ arc_p = (arc_c >> 1);
+
+ /* Set min to 1/2 of arc_c_min */
+ arc_meta_min = 1ULL << SPA_MAXBLOCKSHIFT;
+ /* Initialize maximum observed usage to zero */
+ arc_meta_max = 0;
+ /*
+ * Set arc_meta_limit to a percent of arc_c_max with a floor of
+ * arc_meta_min, and a ceiling of arc_c_max.
+ */
+ percent = MIN(zfs_arc_meta_limit_percent, 100);
+ arc_meta_limit = MAX(arc_meta_min, (percent * arc_c_max) / 100);
+ percent = MIN(zfs_arc_dnode_limit_percent, 100);
+ arc_dnode_size_limit = (percent * arc_meta_limit) / 100;
+
+ /* Apply user specified tunings */
+ arc_tuning_update(B_TRUE);
+
+ /* if kmem_flags are set, lets try to use less memory */
+ if (kmem_debugging())
+ arc_c = arc_c / 2;
+ if (arc_c < arc_c_min)
+ arc_c = arc_c_min;
+
+ arc_state_init();
+
+ buf_init();
+
+ list_create(&arc_prune_list, sizeof (arc_prune_t),
+ offsetof(arc_prune_t, p_node));
+ mutex_init(&arc_prune_mtx, NULL, MUTEX_DEFAULT, NULL);
+
+ arc_prune_taskq = taskq_create("arc_prune", boot_ncpus, defclsyspri,
+ boot_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
+
+ arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED,
+ sizeof (arc_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
+
+ if (arc_ksp != NULL) {
+ arc_ksp->ks_data = &arc_stats;
+ arc_ksp->ks_update = arc_kstat_update;
+ kstat_install(arc_ksp);
+ }
+
+ arc_evict_zthr = zthr_create_timer("arc_evict",
+ arc_evict_cb_check, arc_evict_cb, NULL, SEC2NSEC(1));
+ arc_reap_zthr = zthr_create_timer("arc_reap",
+ arc_reap_cb_check, arc_reap_cb, NULL, SEC2NSEC(1));
+
+ arc_warm = B_FALSE;
+
+ /*
+ * Calculate maximum amount of dirty data per pool.
+ *
+ * If it has been set by a module parameter, take that.
+ * Otherwise, use a percentage of physical memory defined by
+ * zfs_dirty_data_max_percent (default 10%) with a cap at
+ * zfs_dirty_data_max_max (default 4G or 25% of physical memory).
+ */
+#ifdef __LP64__
+ if (zfs_dirty_data_max_max == 0)
+ zfs_dirty_data_max_max = MIN(4ULL * 1024 * 1024 * 1024,
+ allmem * zfs_dirty_data_max_max_percent / 100);
+#else
+ if (zfs_dirty_data_max_max == 0)
+ zfs_dirty_data_max_max = MIN(1ULL * 1024 * 1024 * 1024,
+ allmem * zfs_dirty_data_max_max_percent / 100);
+#endif
+
+ if (zfs_dirty_data_max == 0) {
+ zfs_dirty_data_max = allmem *
+ zfs_dirty_data_max_percent / 100;
+ zfs_dirty_data_max = MIN(zfs_dirty_data_max,
+ zfs_dirty_data_max_max);
+ }
+}
+
+void
+arc_fini(void)
+{
+ arc_prune_t *p;
+
+#ifdef _KERNEL
+ arc_lowmem_fini();
+#endif /* _KERNEL */
+
+ /* Use B_TRUE to ensure *all* buffers are evicted */
+ arc_flush(NULL, B_TRUE);
+
+ if (arc_ksp != NULL) {
+ kstat_delete(arc_ksp);
+ arc_ksp = NULL;
+ }
+
+ taskq_wait(arc_prune_taskq);
+ taskq_destroy(arc_prune_taskq);
+
+ mutex_enter(&arc_prune_mtx);
+ while ((p = list_head(&arc_prune_list)) != NULL) {
+ list_remove(&arc_prune_list, p);
+ zfs_refcount_remove(&p->p_refcnt, &arc_prune_list);
+ zfs_refcount_destroy(&p->p_refcnt);
+ kmem_free(p, sizeof (*p));
+ }
+ mutex_exit(&arc_prune_mtx);
+
+ list_destroy(&arc_prune_list);
+ mutex_destroy(&arc_prune_mtx);
+
+ (void) zthr_cancel(arc_evict_zthr);
+ (void) zthr_cancel(arc_reap_zthr);
+
+ mutex_destroy(&arc_evict_lock);
+ list_destroy(&arc_evict_waiters);
+
+ /*
+ * Free any buffers that were tagged for destruction. This needs
+ * to occur before arc_state_fini() runs and destroys the aggsum
+ * values which are updated when freeing scatter ABDs.
+ */
+ l2arc_do_free_on_write();
+
+ /*
+ * buf_fini() must proceed arc_state_fini() because buf_fin() may
+ * trigger the release of kmem magazines, which can callback to
+ * arc_space_return() which accesses aggsums freed in act_state_fini().
+ */
+ buf_fini();
+ arc_state_fini();
+
+ /*
+ * We destroy the zthrs after all the ARC state has been
+ * torn down to avoid the case of them receiving any
+ * wakeup() signals after they are destroyed.
+ */
+ zthr_destroy(arc_evict_zthr);
+ zthr_destroy(arc_reap_zthr);
+
+ ASSERT0(arc_loaned_bytes);
+}
+
+/*
+ * Level 2 ARC
+ *
+ * The level 2 ARC (L2ARC) is a cache layer in-between main memory and disk.
+ * It uses dedicated storage devices to hold cached data, which are populated
+ * using large infrequent writes. The main role of this cache is to boost
+ * the performance of random read workloads. The intended L2ARC devices
+ * include short-stroked disks, solid state disks, and other media with
+ * substantially faster read latency than disk.
+ *
+ * +-----------------------+
+ * | ARC |
+ * +-----------------------+
+ * | ^ ^
+ * | | |
+ * l2arc_feed_thread() arc_read()
+ * | | |
+ * | l2arc read |
+ * V | |
+ * +---------------+ |
+ * | L2ARC | |
+ * +---------------+ |
+ * | ^ |
+ * l2arc_write() | |
+ * | | |
+ * V | |
+ * +-------+ +-------+
+ * | vdev | | vdev |
+ * | cache | | cache |
+ * +-------+ +-------+
+ * +=========+ .-----.
+ * : L2ARC : |-_____-|
+ * : devices : | Disks |
+ * +=========+ `-_____-'
+ *
+ * Read requests are satisfied from the following sources, in order:
+ *
+ * 1) ARC
+ * 2) vdev cache of L2ARC devices
+ * 3) L2ARC devices
+ * 4) vdev cache of disks
+ * 5) disks
+ *
+ * Some L2ARC device types exhibit extremely slow write performance.
+ * To accommodate for this there are some significant differences between
+ * the L2ARC and traditional cache design:
+ *
+ * 1. There is no eviction path from the ARC to the L2ARC. Evictions from
+ * the ARC behave as usual, freeing buffers and placing headers on ghost
+ * lists. The ARC does not send buffers to the L2ARC during eviction as
+ * this would add inflated write latencies for all ARC memory pressure.
+ *
+ * 2. The L2ARC attempts to cache data from the ARC before it is evicted.
+ * It does this by periodically scanning buffers from the eviction-end of
+ * the MFU and MRU ARC lists, copying them to the L2ARC devices if they are
+ * not already there. It scans until a headroom of buffers is satisfied,
+ * which itself is a buffer for ARC eviction. If a compressible buffer is
+ * found during scanning and selected for writing to an L2ARC device, we
+ * temporarily boost scanning headroom during the next scan cycle to make
+ * sure we adapt to compression effects (which might significantly reduce
+ * the data volume we write to L2ARC). The thread that does this is
+ * l2arc_feed_thread(), illustrated below; example sizes are included to
+ * provide a better sense of ratio than this diagram:
+ *
+ * head --> tail
+ * +---------------------+----------+
+ * ARC_mfu |:::::#:::::::::::::::|o#o###o###|-->. # already on L2ARC
+ * +---------------------+----------+ | o L2ARC eligible
+ * ARC_mru |:#:::::::::::::::::::|#o#ooo####|-->| : ARC buffer
+ * +---------------------+----------+ |
+ * 15.9 Gbytes ^ 32 Mbytes |
+ * headroom |
+ * l2arc_feed_thread()
+ * |
+ * l2arc write hand <--[oooo]--'
+ * | 8 Mbyte
+ * | write max
+ * V
+ * +==============================+
+ * L2ARC dev |####|#|###|###| |####| ... |
+ * +==============================+
+ * 32 Gbytes
+ *
+ * 3. If an ARC buffer is copied to the L2ARC but then hit instead of
+ * evicted, then the L2ARC has cached a buffer much sooner than it probably
+ * needed to, potentially wasting L2ARC device bandwidth and storage. It is
+ * safe to say that this is an uncommon case, since buffers at the end of
+ * the ARC lists have moved there due to inactivity.
+ *
+ * 4. If the ARC evicts faster than the L2ARC can maintain a headroom,
+ * then the L2ARC simply misses copying some buffers. This serves as a
+ * pressure valve to prevent heavy read workloads from both stalling the ARC
+ * with waits and clogging the L2ARC with writes. This also helps prevent
+ * the potential for the L2ARC to churn if it attempts to cache content too
+ * quickly, such as during backups of the entire pool.
+ *
+ * 5. After system boot and before the ARC has filled main memory, there are
+ * no evictions from the ARC and so the tails of the ARC_mfu and ARC_mru
+ * lists can remain mostly static. Instead of searching from tail of these
+ * lists as pictured, the l2arc_feed_thread() will search from the list heads
+ * for eligible buffers, greatly increasing its chance of finding them.
+ *
+ * The L2ARC device write speed is also boosted during this time so that
+ * the L2ARC warms up faster. Since there have been no ARC evictions yet,
+ * there are no L2ARC reads, and no fear of degrading read performance
+ * through increased writes.
+ *
+ * 6. Writes to the L2ARC devices are grouped and sent in-sequence, so that
+ * the vdev queue can aggregate them into larger and fewer writes. Each
+ * device is written to in a rotor fashion, sweeping writes through
+ * available space then repeating.
+ *
+ * 7. The L2ARC does not store dirty content. It never needs to flush
+ * write buffers back to disk based storage.
+ *
+ * 8. If an ARC buffer is written (and dirtied) which also exists in the
+ * L2ARC, the now stale L2ARC buffer is immediately dropped.
+ *
+ * The performance of the L2ARC can be tweaked by a number of tunables, which
+ * may be necessary for different workloads:
+ *
+ * l2arc_write_max max write bytes per interval
+ * l2arc_write_boost extra write bytes during device warmup
+ * l2arc_noprefetch skip caching prefetched buffers
+ * l2arc_headroom number of max device writes to precache
+ * l2arc_headroom_boost when we find compressed buffers during ARC
+ * scanning, we multiply headroom by this
+ * percentage factor for the next scan cycle,
+ * since more compressed buffers are likely to
+ * be present
+ * l2arc_feed_secs seconds between L2ARC writing
+ *
+ * Tunables may be removed or added as future performance improvements are
+ * integrated, and also may become zpool properties.
+ *
+ * There are three key functions that control how the L2ARC warms up:
+ *
+ * l2arc_write_eligible() check if a buffer is eligible to cache
+ * l2arc_write_size() calculate how much to write
+ * l2arc_write_interval() calculate sleep delay between writes
+ *
+ * These three functions determine what to write, how much, and how quickly
+ * to send writes.
+ *
+ * L2ARC persistence:
+ *
+ * When writing buffers to L2ARC, we periodically add some metadata to
+ * make sure we can pick them up after reboot, thus dramatically reducing
+ * the impact that any downtime has on the performance of storage systems
+ * with large caches.
+ *
+ * The implementation works fairly simply by integrating the following two
+ * modifications:
+ *
+ * *) When writing to the L2ARC, we occasionally write a "l2arc log block",
+ * which is an additional piece of metadata which describes what's been
+ * written. This allows us to rebuild the arc_buf_hdr_t structures of the
+ * main ARC buffers. There are 2 linked-lists of log blocks headed by
+ * dh_start_lbps[2]. We alternate which chain we append to, so they are
+ * time-wise and offset-wise interleaved, but that is an optimization rather
+ * than for correctness. The log block also includes a pointer to the
+ * previous block in its chain.
+ *
+ * *) We reserve SPA_MINBLOCKSIZE of space at the start of each L2ARC device
+ * for our header bookkeeping purposes. This contains a device header,
+ * which contains our top-level reference structures. We update it each
+ * time we write a new log block, so that we're able to locate it in the
+ * L2ARC device. If this write results in an inconsistent device header
+ * (e.g. due to power failure), we detect this by verifying the header's
+ * checksum and simply fail to reconstruct the L2ARC after reboot.
+ *
+ * Implementation diagram:
+ *
+ * +=== L2ARC device (not to scale) ======================================+
+ * | ___two newest log block pointers__.__________ |
+ * | / \dh_start_lbps[1] |
+ * | / \ \dh_start_lbps[0]|
+ * |.___/__. V V |
+ * ||L2 dev|....|lb |bufs |lb |bufs |lb |bufs |lb |bufs |lb |---(empty)---|
+ * || hdr| ^ /^ /^ / / |
+ * |+------+ ...--\-------/ \-----/--\------/ / |
+ * | \--------------/ \--------------/ |
+ * +======================================================================+
+ *
+ * As can be seen on the diagram, rather than using a simple linked list,
+ * we use a pair of linked lists with alternating elements. This is a
+ * performance enhancement due to the fact that we only find out the
+ * address of the next log block access once the current block has been
+ * completely read in. Obviously, this hurts performance, because we'd be
+ * keeping the device's I/O queue at only a 1 operation deep, thus
+ * incurring a large amount of I/O round-trip latency. Having two lists
+ * allows us to fetch two log blocks ahead of where we are currently
+ * rebuilding L2ARC buffers.
+ *
+ * On-device data structures:
+ *
+ * L2ARC device header: l2arc_dev_hdr_phys_t
+ * L2ARC log block: l2arc_log_blk_phys_t
+ *
+ * L2ARC reconstruction:
+ *
+ * When writing data, we simply write in the standard rotary fashion,
+ * evicting buffers as we go and simply writing new data over them (writing
+ * a new log block every now and then). This obviously means that once we
+ * loop around the end of the device, we will start cutting into an already
+ * committed log block (and its referenced data buffers), like so:
+ *
+ * current write head__ __old tail
+ * \ /
+ * V V
+ * <--|bufs |lb |bufs |lb | |bufs |lb |bufs |lb |-->
+ * ^ ^^^^^^^^^___________________________________
+ * | \
+ * <<nextwrite>> may overwrite this blk and/or its bufs --'
+ *
+ * When importing the pool, we detect this situation and use it to stop
+ * our scanning process (see l2arc_rebuild).
+ *
+ * There is one significant caveat to consider when rebuilding ARC contents
+ * from an L2ARC device: what about invalidated buffers? Given the above
+ * construction, we cannot update blocks which we've already written to amend
+ * them to remove buffers which were invalidated. Thus, during reconstruction,
+ * we might be populating the cache with buffers for data that's not on the
+ * main pool anymore, or may have been overwritten!
+ *
+ * As it turns out, this isn't a problem. Every arc_read request includes
+ * both the DVA and, crucially, the birth TXG of the BP the caller is
+ * looking for. So even if the cache were populated by completely rotten
+ * blocks for data that had been long deleted and/or overwritten, we'll
+ * never actually return bad data from the cache, since the DVA with the
+ * birth TXG uniquely identify a block in space and time - once created,
+ * a block is immutable on disk. The worst thing we have done is wasted
+ * some time and memory at l2arc rebuild to reconstruct outdated ARC
+ * entries that will get dropped from the l2arc as it is being updated
+ * with new blocks.
+ *
+ * L2ARC buffers that have been evicted by l2arc_evict() ahead of the write
+ * hand are not restored. This is done by saving the offset (in bytes)
+ * l2arc_evict() has evicted to in the L2ARC device header and taking it
+ * into account when restoring buffers.
+ */
+
+static boolean_t
+l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *hdr)
+{
+ /*
+ * A buffer is *not* eligible for the L2ARC if it:
+ * 1. belongs to a different spa.
+ * 2. is already cached on the L2ARC.
+ * 3. has an I/O in progress (it may be an incomplete read).
+ * 4. is flagged not eligible (zfs property).
+ */
+ if (hdr->b_spa != spa_guid || HDR_HAS_L2HDR(hdr) ||
+ HDR_IO_IN_PROGRESS(hdr) || !HDR_L2CACHE(hdr))
+ return (B_FALSE);
+
+ return (B_TRUE);
+}
+
+static uint64_t
+l2arc_write_size(l2arc_dev_t *dev)
+{
+ uint64_t size, dev_size, tsize;
+
+ /*
+ * Make sure our globals have meaningful values in case the user
+ * altered them.
+ */
+ size = l2arc_write_max;
+ if (size == 0) {
+ cmn_err(CE_NOTE, "Bad value for l2arc_write_max, value must "
+ "be greater than zero, resetting it to the default (%d)",
+ L2ARC_WRITE_SIZE);
+ size = l2arc_write_max = L2ARC_WRITE_SIZE;
+ }
+
+ if (arc_warm == B_FALSE)
+ size += l2arc_write_boost;
+
+ /*
+ * Make sure the write size does not exceed the size of the cache
+ * device. This is important in l2arc_evict(), otherwise infinite
+ * iteration can occur.
+ */
+ dev_size = dev->l2ad_end - dev->l2ad_start;
+ tsize = size + l2arc_log_blk_overhead(size, dev);
+ if (dev->l2ad_vdev->vdev_has_trim && l2arc_trim_ahead > 0)
+ tsize += MAX(64 * 1024 * 1024,
+ (tsize * l2arc_trim_ahead) / 100);
+
+ if (tsize >= dev_size) {
+ cmn_err(CE_NOTE, "l2arc_write_max or l2arc_write_boost "
+ "plus the overhead of log blocks (persistent L2ARC, "
+ "%llu bytes) exceeds the size of the cache device "
+ "(guid %llu), resetting them to the default (%d)",
+ l2arc_log_blk_overhead(size, dev),
+ dev->l2ad_vdev->vdev_guid, L2ARC_WRITE_SIZE);
+ size = l2arc_write_max = l2arc_write_boost = L2ARC_WRITE_SIZE;
+
+ if (arc_warm == B_FALSE)
+ size += l2arc_write_boost;
+ }
+
+ return (size);
+
+}
+
+static clock_t
+l2arc_write_interval(clock_t began, uint64_t wanted, uint64_t wrote)
+{
+ clock_t interval, next, now;
+
+ /*
+ * If the ARC lists are busy, increase our write rate; if the
+ * lists are stale, idle back. This is achieved by checking
+ * how much we previously wrote - if it was more than half of
+ * what we wanted, schedule the next write much sooner.
+ */
+ if (l2arc_feed_again && wrote > (wanted / 2))
+ interval = (hz * l2arc_feed_min_ms) / 1000;
+ else
+ interval = hz * l2arc_feed_secs;
+
+ now = ddi_get_lbolt();
+ next = MAX(now, MIN(now + interval, began + interval));
+
+ return (next);
+}
+
+/*
+ * Cycle through L2ARC devices. This is how L2ARC load balances.
+ * If a device is returned, this also returns holding the spa config lock.
+ */
+static l2arc_dev_t *
+l2arc_dev_get_next(void)
+{
+ l2arc_dev_t *first, *next = NULL;
+
+ /*
+ * Lock out the removal of spas (spa_namespace_lock), then removal
+ * of cache devices (l2arc_dev_mtx). Once a device has been selected,
+ * both locks will be dropped and a spa config lock held instead.
+ */
+ mutex_enter(&spa_namespace_lock);
+ mutex_enter(&l2arc_dev_mtx);
+
+ /* if there are no vdevs, there is nothing to do */
+ if (l2arc_ndev == 0)
+ goto out;
+
+ first = NULL;
+ next = l2arc_dev_last;
+ do {
+ /* loop around the list looking for a non-faulted vdev */
+ if (next == NULL) {
+ next = list_head(l2arc_dev_list);
+ } else {
+ next = list_next(l2arc_dev_list, next);
+ if (next == NULL)
+ next = list_head(l2arc_dev_list);
+ }
+
+ /* if we have come back to the start, bail out */
+ if (first == NULL)
+ first = next;
+ else if (next == first)
+ break;
+
+ } while (vdev_is_dead(next->l2ad_vdev) || next->l2ad_rebuild ||
+ next->l2ad_trim_all);
+
+ /* if we were unable to find any usable vdevs, return NULL */
+ if (vdev_is_dead(next->l2ad_vdev) || next->l2ad_rebuild ||
+ next->l2ad_trim_all)
+ next = NULL;
+
+ l2arc_dev_last = next;
+
+out:
+ mutex_exit(&l2arc_dev_mtx);
+
+ /*
+ * Grab the config lock to prevent the 'next' device from being
+ * removed while we are writing to it.
+ */
+ if (next != NULL)
+ spa_config_enter(next->l2ad_spa, SCL_L2ARC, next, RW_READER);
+ mutex_exit(&spa_namespace_lock);
+
+ return (next);
+}
+
+/*
+ * Free buffers that were tagged for destruction.
+ */
+static void
+l2arc_do_free_on_write(void)
+{
+ list_t *buflist;
+ l2arc_data_free_t *df, *df_prev;
+
+ mutex_enter(&l2arc_free_on_write_mtx);
+ buflist = l2arc_free_on_write;
+
+ for (df = list_tail(buflist); df; df = df_prev) {
+ df_prev = list_prev(buflist, df);
+ ASSERT3P(df->l2df_abd, !=, NULL);
+ abd_free(df->l2df_abd);
+ list_remove(buflist, df);
+ kmem_free(df, sizeof (l2arc_data_free_t));
+ }
+
+ mutex_exit(&l2arc_free_on_write_mtx);
+}
+
+/*
+ * A write to a cache device has completed. Update all headers to allow
+ * reads from these buffers to begin.
+ */
+static void
+l2arc_write_done(zio_t *zio)
+{
+ l2arc_write_callback_t *cb;
+ l2arc_lb_abd_buf_t *abd_buf;
+ l2arc_lb_ptr_buf_t *lb_ptr_buf;
+ l2arc_dev_t *dev;
+ l2arc_dev_hdr_phys_t *l2dhdr;
+ list_t *buflist;
+ arc_buf_hdr_t *head, *hdr, *hdr_prev;
+ kmutex_t *hash_lock;
+ int64_t bytes_dropped = 0;
+
+ cb = zio->io_private;
+ ASSERT3P(cb, !=, NULL);
+ dev = cb->l2wcb_dev;
+ l2dhdr = dev->l2ad_dev_hdr;
+ ASSERT3P(dev, !=, NULL);
+ head = cb->l2wcb_head;
+ ASSERT3P(head, !=, NULL);
+ buflist = &dev->l2ad_buflist;
+ ASSERT3P(buflist, !=, NULL);
+ DTRACE_PROBE2(l2arc__iodone, zio_t *, zio,
+ l2arc_write_callback_t *, cb);
+
+ if (zio->io_error != 0)
+ ARCSTAT_BUMP(arcstat_l2_writes_error);
+
+ /*
+ * All writes completed, or an error was hit.
+ */
+top:
+ mutex_enter(&dev->l2ad_mtx);
+ for (hdr = list_prev(buflist, head); hdr; hdr = hdr_prev) {
+ hdr_prev = list_prev(buflist, hdr);
+
+ hash_lock = HDR_LOCK(hdr);
+
+ /*
+ * We cannot use mutex_enter or else we can deadlock
+ * with l2arc_write_buffers (due to swapping the order
+ * the hash lock and l2ad_mtx are taken).
+ */
+ if (!mutex_tryenter(hash_lock)) {
+ /*
+ * Missed the hash lock. We must retry so we
+ * don't leave the ARC_FLAG_L2_WRITING bit set.
+ */
+ ARCSTAT_BUMP(arcstat_l2_writes_lock_retry);
+
+ /*
+ * We don't want to rescan the headers we've
+ * already marked as having been written out, so
+ * we reinsert the head node so we can pick up
+ * where we left off.
+ */
+ list_remove(buflist, head);
+ list_insert_after(buflist, hdr, head);
+
+ mutex_exit(&dev->l2ad_mtx);
+
+ /*
+ * We wait for the hash lock to become available
+ * to try and prevent busy waiting, and increase
+ * the chance we'll be able to acquire the lock
+ * the next time around.
+ */
+ mutex_enter(hash_lock);
+ mutex_exit(hash_lock);
+ goto top;
+ }
+
+ /*
+ * We could not have been moved into the arc_l2c_only
+ * state while in-flight due to our ARC_FLAG_L2_WRITING
+ * bit being set. Let's just ensure that's being enforced.
+ */
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ /*
+ * Skipped - drop L2ARC entry and mark the header as no
+ * longer L2 eligibile.
+ */
+ if (zio->io_error != 0) {
+ /*
+ * Error - drop L2ARC entry.
+ */
+ list_remove(buflist, hdr);
+ arc_hdr_clear_flags(hdr, ARC_FLAG_HAS_L2HDR);
+
+ uint64_t psize = HDR_GET_PSIZE(hdr);
+ ARCSTAT_INCR(arcstat_l2_psize, -psize);
+ ARCSTAT_INCR(arcstat_l2_lsize, -HDR_GET_LSIZE(hdr));
+
+ bytes_dropped +=
+ vdev_psize_to_asize(dev->l2ad_vdev, psize);
+ (void) zfs_refcount_remove_many(&dev->l2ad_alloc,
+ arc_hdr_size(hdr), hdr);
+ }
+
+ /*
+ * Allow ARC to begin reads and ghost list evictions to
+ * this L2ARC entry.
+ */
+ arc_hdr_clear_flags(hdr, ARC_FLAG_L2_WRITING);
+
+ mutex_exit(hash_lock);
+ }
+
+ /*
+ * Free the allocated abd buffers for writing the log blocks.
+ * If the zio failed reclaim the allocated space and remove the
+ * pointers to these log blocks from the log block pointer list
+ * of the L2ARC device.
+ */
+ while ((abd_buf = list_remove_tail(&cb->l2wcb_abd_list)) != NULL) {
+ abd_free(abd_buf->abd);
+ zio_buf_free(abd_buf, sizeof (*abd_buf));
+ if (zio->io_error != 0) {
+ lb_ptr_buf = list_remove_head(&dev->l2ad_lbptr_list);
+ /*
+ * L2BLK_GET_PSIZE returns aligned size for log
+ * blocks.
+ */
+ uint64_t asize =
+ L2BLK_GET_PSIZE((lb_ptr_buf->lb_ptr)->lbp_prop);
+ bytes_dropped += asize;
+ ARCSTAT_INCR(arcstat_l2_log_blk_asize, -asize);
+ ARCSTAT_BUMPDOWN(arcstat_l2_log_blk_count);
+ zfs_refcount_remove_many(&dev->l2ad_lb_asize, asize,
+ lb_ptr_buf);
+ zfs_refcount_remove(&dev->l2ad_lb_count, lb_ptr_buf);
+ kmem_free(lb_ptr_buf->lb_ptr,
+ sizeof (l2arc_log_blkptr_t));
+ kmem_free(lb_ptr_buf, sizeof (l2arc_lb_ptr_buf_t));
+ }
+ }
+ list_destroy(&cb->l2wcb_abd_list);
+
+ if (zio->io_error != 0) {
+ /*
+ * Restore the lbps array in the header to its previous state.
+ * If the list of log block pointers is empty, zero out the
+ * log block pointers in the device header.
+ */
+ lb_ptr_buf = list_head(&dev->l2ad_lbptr_list);
+ for (int i = 0; i < 2; i++) {
+ if (lb_ptr_buf == NULL) {
+ /*
+ * If the list is empty zero out the device
+ * header. Otherwise zero out the second log
+ * block pointer in the header.
+ */
+ if (i == 0) {
+ bzero(l2dhdr, dev->l2ad_dev_hdr_asize);
+ } else {
+ bzero(&l2dhdr->dh_start_lbps[i],
+ sizeof (l2arc_log_blkptr_t));
+ }
+ break;
+ }
+ bcopy(lb_ptr_buf->lb_ptr, &l2dhdr->dh_start_lbps[i],
+ sizeof (l2arc_log_blkptr_t));
+ lb_ptr_buf = list_next(&dev->l2ad_lbptr_list,
+ lb_ptr_buf);
+ }
+ }
+
+ atomic_inc_64(&l2arc_writes_done);
+ list_remove(buflist, head);
+ ASSERT(!HDR_HAS_L1HDR(head));
+ kmem_cache_free(hdr_l2only_cache, head);
+ mutex_exit(&dev->l2ad_mtx);
+
+ ASSERT(dev->l2ad_vdev != NULL);
+ vdev_space_update(dev->l2ad_vdev, -bytes_dropped, 0, 0);
+
+ l2arc_do_free_on_write();
+
+ kmem_free(cb, sizeof (l2arc_write_callback_t));
+}
+
+static int
+l2arc_untransform(zio_t *zio, l2arc_read_callback_t *cb)
+{
+ int ret;
+ spa_t *spa = zio->io_spa;
+ arc_buf_hdr_t *hdr = cb->l2rcb_hdr;
+ blkptr_t *bp = zio->io_bp;
+ uint8_t salt[ZIO_DATA_SALT_LEN];
+ uint8_t iv[ZIO_DATA_IV_LEN];
+ uint8_t mac[ZIO_DATA_MAC_LEN];
+ boolean_t no_crypt = B_FALSE;
+
+ /*
+ * ZIL data is never be written to the L2ARC, so we don't need
+ * special handling for its unique MAC storage.
+ */
+ ASSERT3U(BP_GET_TYPE(bp), !=, DMU_OT_INTENT_LOG);
+ ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+
+ /*
+ * If the data was encrypted, decrypt it now. Note that
+ * we must check the bp here and not the hdr, since the
+ * hdr does not have its encryption parameters updated
+ * until arc_read_done().
+ */
+ if (BP_IS_ENCRYPTED(bp)) {
+ abd_t *eabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr,
+ B_TRUE);
+
+ zio_crypt_decode_params_bp(bp, salt, iv);
+ zio_crypt_decode_mac_bp(bp, mac);
+
+ ret = spa_do_crypt_abd(B_FALSE, spa, &cb->l2rcb_zb,
+ BP_GET_TYPE(bp), BP_GET_DEDUP(bp), BP_SHOULD_BYTESWAP(bp),
+ salt, iv, mac, HDR_GET_PSIZE(hdr), eabd,
+ hdr->b_l1hdr.b_pabd, &no_crypt);
+ if (ret != 0) {
+ arc_free_data_abd(hdr, eabd, arc_hdr_size(hdr), hdr);
+ goto error;
+ }
+
+ /*
+ * If we actually performed decryption, replace b_pabd
+ * with the decrypted data. Otherwise we can just throw
+ * our decryption buffer away.
+ */
+ if (!no_crypt) {
+ arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
+ arc_hdr_size(hdr), hdr);
+ hdr->b_l1hdr.b_pabd = eabd;
+ zio->io_abd = eabd;
+ } else {
+ arc_free_data_abd(hdr, eabd, arc_hdr_size(hdr), hdr);
+ }
+ }
+
+ /*
+ * If the L2ARC block was compressed, but ARC compression
+ * is disabled we decompress the data into a new buffer and
+ * replace the existing data.
+ */
+ if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
+ !HDR_COMPRESSION_ENABLED(hdr)) {
+ abd_t *cabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr,
+ B_TRUE);
+ void *tmp = abd_borrow_buf(cabd, arc_hdr_size(hdr));
+
+ ret = zio_decompress_data(HDR_GET_COMPRESS(hdr),
+ hdr->b_l1hdr.b_pabd, tmp, HDR_GET_PSIZE(hdr),
+ HDR_GET_LSIZE(hdr), &hdr->b_complevel);
+ if (ret != 0) {
+ abd_return_buf_copy(cabd, tmp, arc_hdr_size(hdr));
+ arc_free_data_abd(hdr, cabd, arc_hdr_size(hdr), hdr);
+ goto error;
+ }
+
+ abd_return_buf_copy(cabd, tmp, arc_hdr_size(hdr));
+ arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
+ arc_hdr_size(hdr), hdr);
+ hdr->b_l1hdr.b_pabd = cabd;
+ zio->io_abd = cabd;
+ zio->io_size = HDR_GET_LSIZE(hdr);
+ }
+
+ return (0);
+
+error:
+ return (ret);
+}
+
+
+/*
+ * A read to a cache device completed. Validate buffer contents before
+ * handing over to the regular ARC routines.
+ */
+static void
+l2arc_read_done(zio_t *zio)
+{
+ int tfm_error = 0;
+ l2arc_read_callback_t *cb = zio->io_private;
+ arc_buf_hdr_t *hdr;
+ kmutex_t *hash_lock;
+ boolean_t valid_cksum;
+ boolean_t using_rdata = (BP_IS_ENCRYPTED(&cb->l2rcb_bp) &&
+ (cb->l2rcb_flags & ZIO_FLAG_RAW_ENCRYPT));
+
+ ASSERT3P(zio->io_vd, !=, NULL);
+ ASSERT(zio->io_flags & ZIO_FLAG_DONT_PROPAGATE);
+
+ spa_config_exit(zio->io_spa, SCL_L2ARC, zio->io_vd);
+
+ ASSERT3P(cb, !=, NULL);
+ hdr = cb->l2rcb_hdr;
+ ASSERT3P(hdr, !=, NULL);
+
+ hash_lock = HDR_LOCK(hdr);
+ mutex_enter(hash_lock);
+ ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
+
+ /*
+ * If the data was read into a temporary buffer,
+ * move it and free the buffer.
+ */
+ if (cb->l2rcb_abd != NULL) {
+ ASSERT3U(arc_hdr_size(hdr), <, zio->io_size);
+ if (zio->io_error == 0) {
+ if (using_rdata) {
+ abd_copy(hdr->b_crypt_hdr.b_rabd,
+ cb->l2rcb_abd, arc_hdr_size(hdr));
+ } else {
+ abd_copy(hdr->b_l1hdr.b_pabd,
+ cb->l2rcb_abd, arc_hdr_size(hdr));
+ }
+ }
+
+ /*
+ * The following must be done regardless of whether
+ * there was an error:
+ * - free the temporary buffer
+ * - point zio to the real ARC buffer
+ * - set zio size accordingly
+ * These are required because zio is either re-used for
+ * an I/O of the block in the case of the error
+ * or the zio is passed to arc_read_done() and it
+ * needs real data.
+ */
+ abd_free(cb->l2rcb_abd);
+ zio->io_size = zio->io_orig_size = arc_hdr_size(hdr);
+
+ if (using_rdata) {
+ ASSERT(HDR_HAS_RABD(hdr));
+ zio->io_abd = zio->io_orig_abd =
+ hdr->b_crypt_hdr.b_rabd;
+ } else {
+ ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
+ zio->io_abd = zio->io_orig_abd = hdr->b_l1hdr.b_pabd;
+ }
+ }
+
+ ASSERT3P(zio->io_abd, !=, NULL);
+
+ /*
+ * Check this survived the L2ARC journey.
+ */
+ ASSERT(zio->io_abd == hdr->b_l1hdr.b_pabd ||
+ (HDR_HAS_RABD(hdr) && zio->io_abd == hdr->b_crypt_hdr.b_rabd));
+ zio->io_bp_copy = cb->l2rcb_bp; /* XXX fix in L2ARC 2.0 */
+ zio->io_bp = &zio->io_bp_copy; /* XXX fix in L2ARC 2.0 */
+ zio->io_prop.zp_complevel = hdr->b_complevel;
+
+ valid_cksum = arc_cksum_is_equal(hdr, zio);
+
+ /*
+ * b_rabd will always match the data as it exists on disk if it is
+ * being used. Therefore if we are reading into b_rabd we do not
+ * attempt to untransform the data.
+ */
+ if (valid_cksum && !using_rdata)
+ tfm_error = l2arc_untransform(zio, cb);
+
+ if (valid_cksum && tfm_error == 0 && zio->io_error == 0 &&
+ !HDR_L2_EVICTED(hdr)) {
+ mutex_exit(hash_lock);
+ zio->io_private = hdr;
+ arc_read_done(zio);
+ } else {
+ /*
+ * Buffer didn't survive caching. Increment stats and
+ * reissue to the original storage device.
+ */
+ if (zio->io_error != 0) {
+ ARCSTAT_BUMP(arcstat_l2_io_error);
+ } else {
+ zio->io_error = SET_ERROR(EIO);
+ }
+ if (!valid_cksum || tfm_error != 0)
+ ARCSTAT_BUMP(arcstat_l2_cksum_bad);
+
+ /*
+ * If there's no waiter, issue an async i/o to the primary
+ * storage now. If there *is* a waiter, the caller must
+ * issue the i/o in a context where it's OK to block.
+ */
+ if (zio->io_waiter == NULL) {
+ zio_t *pio = zio_unique_parent(zio);
+ void *abd = (using_rdata) ?
+ hdr->b_crypt_hdr.b_rabd : hdr->b_l1hdr.b_pabd;
+
+ ASSERT(!pio || pio->io_child_type == ZIO_CHILD_LOGICAL);
+
+ zio = zio_read(pio, zio->io_spa, zio->io_bp,
+ abd, zio->io_size, arc_read_done,
+ hdr, zio->io_priority, cb->l2rcb_flags,
+ &cb->l2rcb_zb);
+
+ /*
+ * Original ZIO will be freed, so we need to update
+ * ARC header with the new ZIO pointer to be used
+ * by zio_change_priority() in arc_read().
+ */
+ for (struct arc_callback *acb = hdr->b_l1hdr.b_acb;
+ acb != NULL; acb = acb->acb_next)
+ acb->acb_zio_head = zio;
+
+ mutex_exit(hash_lock);
+ zio_nowait(zio);
+ } else {
+ mutex_exit(hash_lock);
+ }
+ }
+
+ kmem_free(cb, sizeof (l2arc_read_callback_t));
+}
+
+/*
+ * This is the list priority from which the L2ARC will search for pages to
+ * cache. This is used within loops (0..3) to cycle through lists in the
+ * desired order. This order can have a significant effect on cache
+ * performance.
+ *
+ * Currently the metadata lists are hit first, MFU then MRU, followed by
+ * the data lists. This function returns a locked list, and also returns
+ * the lock pointer.
+ */
+static multilist_sublist_t *
+l2arc_sublist_lock(int list_num)
+{
+ multilist_t *ml = NULL;
+ unsigned int idx;
+
+ ASSERT(list_num >= 0 && list_num < L2ARC_FEED_TYPES);
+
+ switch (list_num) {
+ case 0:
+ ml = arc_mfu->arcs_list[ARC_BUFC_METADATA];
+ break;
+ case 1:
+ ml = arc_mru->arcs_list[ARC_BUFC_METADATA];
+ break;
+ case 2:
+ ml = arc_mfu->arcs_list[ARC_BUFC_DATA];
+ break;
+ case 3:
+ ml = arc_mru->arcs_list[ARC_BUFC_DATA];
+ break;
+ default:
+ return (NULL);
+ }
+
+ /*
+ * Return a randomly-selected sublist. This is acceptable
+ * because the caller feeds only a little bit of data for each
+ * call (8MB). Subsequent calls will result in different
+ * sublists being selected.
+ */
+ idx = multilist_get_random_index(ml);
+ return (multilist_sublist_lock(ml, idx));
+}
+
+/*
+ * Calculates the maximum overhead of L2ARC metadata log blocks for a given
+ * L2ARC write size. l2arc_evict and l2arc_write_size need to include this
+ * overhead in processing to make sure there is enough headroom available
+ * when writing buffers.
+ */
+static inline uint64_t
+l2arc_log_blk_overhead(uint64_t write_sz, l2arc_dev_t *dev)
+{
+ if (dev->l2ad_log_entries == 0) {
+ return (0);
+ } else {
+ uint64_t log_entries = write_sz >> SPA_MINBLOCKSHIFT;
+
+ uint64_t log_blocks = (log_entries +
+ dev->l2ad_log_entries - 1) /
+ dev->l2ad_log_entries;
+
+ return (vdev_psize_to_asize(dev->l2ad_vdev,
+ sizeof (l2arc_log_blk_phys_t)) * log_blocks);
+ }
+}
+
+/*
+ * Evict buffers from the device write hand to the distance specified in
+ * bytes. This distance may span populated buffers, it may span nothing.
+ * This is clearing a region on the L2ARC device ready for writing.
+ * If the 'all' boolean is set, every buffer is evicted.
+ */
+static void
+l2arc_evict(l2arc_dev_t *dev, uint64_t distance, boolean_t all)
+{
+ list_t *buflist;
+ arc_buf_hdr_t *hdr, *hdr_prev;
+ kmutex_t *hash_lock;
+ uint64_t taddr;
+ l2arc_lb_ptr_buf_t *lb_ptr_buf, *lb_ptr_buf_prev;
+ vdev_t *vd = dev->l2ad_vdev;
+ boolean_t rerun;
+
+ buflist = &dev->l2ad_buflist;
+
+ /*
+ * We need to add in the worst case scenario of log block overhead.
+ */
+ distance += l2arc_log_blk_overhead(distance, dev);
+ if (vd->vdev_has_trim && l2arc_trim_ahead > 0) {
+ /*
+ * Trim ahead of the write size 64MB or (l2arc_trim_ahead/100)
+ * times the write size, whichever is greater.
+ */
+ distance += MAX(64 * 1024 * 1024,
+ (distance * l2arc_trim_ahead) / 100);
+ }
+
+top:
+ rerun = B_FALSE;
+ if (dev->l2ad_hand >= (dev->l2ad_end - distance)) {
+ /*
+ * When there is no space to accommodate upcoming writes,
+ * evict to the end. Then bump the write and evict hands
+ * to the start and iterate. This iteration does not
+ * happen indefinitely as we make sure in
+ * l2arc_write_size() that when the write hand is reset,
+ * the write size does not exceed the end of the device.
+ */
+ rerun = B_TRUE;
+ taddr = dev->l2ad_end;
+ } else {
+ taddr = dev->l2ad_hand + distance;
+ }
+ DTRACE_PROBE4(l2arc__evict, l2arc_dev_t *, dev, list_t *, buflist,
+ uint64_t, taddr, boolean_t, all);
+
+ if (!all) {
+ /*
+ * This check has to be placed after deciding whether to
+ * iterate (rerun).
+ */
+ if (dev->l2ad_first) {
+ /*
+ * This is the first sweep through the device. There is
+ * nothing to evict. We have already trimmmed the
+ * whole device.
+ */
+ goto out;
+ } else {
+ /*
+ * Trim the space to be evicted.
+ */
+ if (vd->vdev_has_trim && dev->l2ad_evict < taddr &&
+ l2arc_trim_ahead > 0) {
+ /*
+ * We have to drop the spa_config lock because
+ * vdev_trim_range() will acquire it.
+ * l2ad_evict already accounts for the label
+ * size. To prevent vdev_trim_ranges() from
+ * adding it again, we subtract it from
+ * l2ad_evict.
+ */
+ spa_config_exit(dev->l2ad_spa, SCL_L2ARC, dev);
+ vdev_trim_simple(vd,
+ dev->l2ad_evict - VDEV_LABEL_START_SIZE,
+ taddr - dev->l2ad_evict);
+ spa_config_enter(dev->l2ad_spa, SCL_L2ARC, dev,
+ RW_READER);
+ }
+
+ /*
+ * When rebuilding L2ARC we retrieve the evict hand
+ * from the header of the device. Of note, l2arc_evict()
+ * does not actually delete buffers from the cache
+ * device, but trimming may do so depending on the
+ * hardware implementation. Thus keeping track of the
+ * evict hand is useful.
+ */
+ dev->l2ad_evict = MAX(dev->l2ad_evict, taddr);
+ }
+ }
+
+retry:
+ mutex_enter(&dev->l2ad_mtx);
+ /*
+ * We have to account for evicted log blocks. Run vdev_space_update()
+ * on log blocks whose offset (in bytes) is before the evicted offset
+ * (in bytes) by searching in the list of pointers to log blocks
+ * present in the L2ARC device.
+ */
+ for (lb_ptr_buf = list_tail(&dev->l2ad_lbptr_list); lb_ptr_buf;
+ lb_ptr_buf = lb_ptr_buf_prev) {
+
+ lb_ptr_buf_prev = list_prev(&dev->l2ad_lbptr_list, lb_ptr_buf);
+
+ /* L2BLK_GET_PSIZE returns aligned size for log blocks */
+ uint64_t asize = L2BLK_GET_PSIZE(
+ (lb_ptr_buf->lb_ptr)->lbp_prop);
+
+ /*
+ * We don't worry about log blocks left behind (ie
+ * lbp_payload_start < l2ad_hand) because l2arc_write_buffers()
+ * will never write more than l2arc_evict() evicts.
+ */
+ if (!all && l2arc_log_blkptr_valid(dev, lb_ptr_buf->lb_ptr)) {
+ break;
+ } else {
+ vdev_space_update(vd, -asize, 0, 0);
+ ARCSTAT_INCR(arcstat_l2_log_blk_asize, -asize);
+ ARCSTAT_BUMPDOWN(arcstat_l2_log_blk_count);
+ zfs_refcount_remove_many(&dev->l2ad_lb_asize, asize,
+ lb_ptr_buf);
+ zfs_refcount_remove(&dev->l2ad_lb_count, lb_ptr_buf);
+ list_remove(&dev->l2ad_lbptr_list, lb_ptr_buf);
+ kmem_free(lb_ptr_buf->lb_ptr,
+ sizeof (l2arc_log_blkptr_t));
+ kmem_free(lb_ptr_buf, sizeof (l2arc_lb_ptr_buf_t));
+ }
+ }
+
+ for (hdr = list_tail(buflist); hdr; hdr = hdr_prev) {
+ hdr_prev = list_prev(buflist, hdr);
+
+ ASSERT(!HDR_EMPTY(hdr));
+ hash_lock = HDR_LOCK(hdr);
+
+ /*
+ * We cannot use mutex_enter or else we can deadlock
+ * with l2arc_write_buffers (due to swapping the order
+ * the hash lock and l2ad_mtx are taken).
+ */
+ if (!mutex_tryenter(hash_lock)) {
+ /*
+ * Missed the hash lock. Retry.
+ */
+ ARCSTAT_BUMP(arcstat_l2_evict_lock_retry);
+ mutex_exit(&dev->l2ad_mtx);
+ mutex_enter(hash_lock);
+ mutex_exit(hash_lock);
+ goto retry;
+ }
+
+ /*
+ * A header can't be on this list if it doesn't have L2 header.
+ */
+ ASSERT(HDR_HAS_L2HDR(hdr));
+
+ /* Ensure this header has finished being written. */
+ ASSERT(!HDR_L2_WRITING(hdr));
+ ASSERT(!HDR_L2_WRITE_HEAD(hdr));
+
+ if (!all && (hdr->b_l2hdr.b_daddr >= dev->l2ad_evict ||
+ hdr->b_l2hdr.b_daddr < dev->l2ad_hand)) {
+ /*
+ * We've evicted to the target address,
+ * or the end of the device.
+ */
+ mutex_exit(hash_lock);
+ break;
+ }
+
+ if (!HDR_HAS_L1HDR(hdr)) {
+ ASSERT(!HDR_L2_READING(hdr));
+ /*
+ * This doesn't exist in the ARC. Destroy.
+ * arc_hdr_destroy() will call list_remove()
+ * and decrement arcstat_l2_lsize.
+ */
+ arc_change_state(arc_anon, hdr, hash_lock);
+ arc_hdr_destroy(hdr);
+ } else {
+ ASSERT(hdr->b_l1hdr.b_state != arc_l2c_only);
+ ARCSTAT_BUMP(arcstat_l2_evict_l1cached);
+ /*
+ * Invalidate issued or about to be issued
+ * reads, since we may be about to write
+ * over this location.
+ */
+ if (HDR_L2_READING(hdr)) {
+ ARCSTAT_BUMP(arcstat_l2_evict_reading);
+ arc_hdr_set_flags(hdr, ARC_FLAG_L2_EVICTED);
+ }
+
+ arc_hdr_l2hdr_destroy(hdr);
+ }
+ mutex_exit(hash_lock);
+ }
+ mutex_exit(&dev->l2ad_mtx);
+
+out:
+ /*
+ * We need to check if we evict all buffers, otherwise we may iterate
+ * unnecessarily.
+ */
+ if (!all && rerun) {
+ /*
+ * Bump device hand to the device start if it is approaching the
+ * end. l2arc_evict() has already evicted ahead for this case.
+ */
+ dev->l2ad_hand = dev->l2ad_start;
+ dev->l2ad_evict = dev->l2ad_start;
+ dev->l2ad_first = B_FALSE;
+ goto top;
+ }
+
+ ASSERT3U(dev->l2ad_hand + distance, <, dev->l2ad_end);
+ if (!dev->l2ad_first)
+ ASSERT3U(dev->l2ad_hand, <, dev->l2ad_evict);
+}
+
+/*
+ * Handle any abd transforms that might be required for writing to the L2ARC.
+ * If successful, this function will always return an abd with the data
+ * transformed as it is on disk in a new abd of asize bytes.
+ */
+static int
+l2arc_apply_transforms(spa_t *spa, arc_buf_hdr_t *hdr, uint64_t asize,
+ abd_t **abd_out)
+{
+ int ret;
+ void *tmp = NULL;
+ abd_t *cabd = NULL, *eabd = NULL, *to_write = hdr->b_l1hdr.b_pabd;
+ enum zio_compress compress = HDR_GET_COMPRESS(hdr);
+ uint64_t psize = HDR_GET_PSIZE(hdr);
+ uint64_t size = arc_hdr_size(hdr);
+ boolean_t ismd = HDR_ISTYPE_METADATA(hdr);
+ boolean_t bswap = (hdr->b_l1hdr.b_byteswap != DMU_BSWAP_NUMFUNCS);
+ dsl_crypto_key_t *dck = NULL;
+ uint8_t mac[ZIO_DATA_MAC_LEN] = { 0 };
+ boolean_t no_crypt = B_FALSE;
+
+ ASSERT((HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
+ !HDR_COMPRESSION_ENABLED(hdr)) ||
+ HDR_ENCRYPTED(hdr) || HDR_SHARED_DATA(hdr) || psize != asize);
+ ASSERT3U(psize, <=, asize);
+
+ /*
+ * If this data simply needs its own buffer, we simply allocate it
+ * and copy the data. This may be done to eliminate a dependency on a
+ * shared buffer or to reallocate the buffer to match asize.
+ */
+ if (HDR_HAS_RABD(hdr) && asize != psize) {
+ ASSERT3U(asize, >=, psize);
+ to_write = abd_alloc_for_io(asize, ismd);
+ abd_copy(to_write, hdr->b_crypt_hdr.b_rabd, psize);
+ if (psize != asize)
+ abd_zero_off(to_write, psize, asize - psize);
+ goto out;
+ }
+
+ if ((compress == ZIO_COMPRESS_OFF || HDR_COMPRESSION_ENABLED(hdr)) &&
+ !HDR_ENCRYPTED(hdr)) {
+ ASSERT3U(size, ==, psize);
+ to_write = abd_alloc_for_io(asize, ismd);
+ abd_copy(to_write, hdr->b_l1hdr.b_pabd, size);
+ if (size != asize)
+ abd_zero_off(to_write, size, asize - size);
+ goto out;
+ }
+
+ if (compress != ZIO_COMPRESS_OFF && !HDR_COMPRESSION_ENABLED(hdr)) {
+ cabd = abd_alloc_for_io(asize, ismd);
+ tmp = abd_borrow_buf(cabd, asize);
+
+ psize = zio_compress_data(compress, to_write, tmp, size,
+ hdr->b_complevel);
+
+ if (psize >= size) {
+ abd_return_buf(cabd, tmp, asize);
+ HDR_SET_COMPRESS(hdr, ZIO_COMPRESS_OFF);
+ to_write = cabd;
+ abd_copy(to_write, hdr->b_l1hdr.b_pabd, size);
+ if (size != asize)
+ abd_zero_off(to_write, size, asize - size);
+ goto encrypt;
+ }
+ ASSERT3U(psize, <=, HDR_GET_PSIZE(hdr));
+ if (psize < asize)
+ bzero((char *)tmp + psize, asize - psize);
+ psize = HDR_GET_PSIZE(hdr);
+ abd_return_buf_copy(cabd, tmp, asize);
+ to_write = cabd;
+ }
+
+encrypt:
+ if (HDR_ENCRYPTED(hdr)) {
+ eabd = abd_alloc_for_io(asize, ismd);
+
+ /*
+ * If the dataset was disowned before the buffer
+ * made it to this point, the key to re-encrypt
+ * it won't be available. In this case we simply
+ * won't write the buffer to the L2ARC.
+ */
+ ret = spa_keystore_lookup_key(spa, hdr->b_crypt_hdr.b_dsobj,
+ FTAG, &dck);
+ if (ret != 0)
+ goto error;
+
+ ret = zio_do_crypt_abd(B_TRUE, &dck->dck_key,
+ hdr->b_crypt_hdr.b_ot, bswap, hdr->b_crypt_hdr.b_salt,
+ hdr->b_crypt_hdr.b_iv, mac, psize, to_write, eabd,
+ &no_crypt);
+ if (ret != 0)
+ goto error;
+
+ if (no_crypt)
+ abd_copy(eabd, to_write, psize);
+
+ if (psize != asize)
+ abd_zero_off(eabd, psize, asize - psize);
+
+ /* assert that the MAC we got here matches the one we saved */
+ ASSERT0(bcmp(mac, hdr->b_crypt_hdr.b_mac, ZIO_DATA_MAC_LEN));
+ spa_keystore_dsl_key_rele(spa, dck, FTAG);
+
+ if (to_write == cabd)
+ abd_free(cabd);
+
+ to_write = eabd;
+ }
+
+out:
+ ASSERT3P(to_write, !=, hdr->b_l1hdr.b_pabd);
+ *abd_out = to_write;
+ return (0);
+
+error:
+ if (dck != NULL)
+ spa_keystore_dsl_key_rele(spa, dck, FTAG);
+ if (cabd != NULL)
+ abd_free(cabd);
+ if (eabd != NULL)
+ abd_free(eabd);
+
+ *abd_out = NULL;
+ return (ret);
+}
+
+static void
+l2arc_blk_fetch_done(zio_t *zio)
+{
+ l2arc_read_callback_t *cb;
+
+ cb = zio->io_private;
+ if (cb->l2rcb_abd != NULL)
+ abd_put(cb->l2rcb_abd);
+ kmem_free(cb, sizeof (l2arc_read_callback_t));
+}
+
+/*
+ * Find and write ARC buffers to the L2ARC device.
+ *
+ * An ARC_FLAG_L2_WRITING flag is set so that the L2ARC buffers are not valid
+ * for reading until they have completed writing.
+ * The headroom_boost is an in-out parameter used to maintain headroom boost
+ * state between calls to this function.
+ *
+ * Returns the number of bytes actually written (which may be smaller than
+ * the delta by which the device hand has changed due to alignment and the
+ * writing of log blocks).
+ */
+static uint64_t
+l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
+{
+ arc_buf_hdr_t *hdr, *hdr_prev, *head;
+ uint64_t write_asize, write_psize, write_lsize, headroom;
+ boolean_t full;
+ l2arc_write_callback_t *cb = NULL;
+ zio_t *pio, *wzio;
+ uint64_t guid = spa_load_guid(spa);
+
+ ASSERT3P(dev->l2ad_vdev, !=, NULL);
+
+ pio = NULL;
+ write_lsize = write_asize = write_psize = 0;
+ full = B_FALSE;
+ head = kmem_cache_alloc(hdr_l2only_cache, KM_PUSHPAGE);
+ arc_hdr_set_flags(head, ARC_FLAG_L2_WRITE_HEAD | ARC_FLAG_HAS_L2HDR);
+
+ /*
+ * Copy buffers for L2ARC writing.
+ */
+ for (int try = 0; try < L2ARC_FEED_TYPES; try++) {
+ multilist_sublist_t *mls = l2arc_sublist_lock(try);
+ uint64_t passed_sz = 0;
+
+ VERIFY3P(mls, !=, NULL);
+
+ /*
+ * L2ARC fast warmup.
+ *
+ * Until the ARC is warm and starts to evict, read from the
+ * head of the ARC lists rather than the tail.
+ */
+ if (arc_warm == B_FALSE)
+ hdr = multilist_sublist_head(mls);
+ else
+ hdr = multilist_sublist_tail(mls);
+
+ headroom = target_sz * l2arc_headroom;
+ if (zfs_compressed_arc_enabled)
+ headroom = (headroom * l2arc_headroom_boost) / 100;
+
+ for (; hdr; hdr = hdr_prev) {
+ kmutex_t *hash_lock;
+ abd_t *to_write = NULL;
+
+ if (arc_warm == B_FALSE)
+ hdr_prev = multilist_sublist_next(mls, hdr);
+ else
+ hdr_prev = multilist_sublist_prev(mls, hdr);
+
+ hash_lock = HDR_LOCK(hdr);
+ if (!mutex_tryenter(hash_lock)) {
+ /*
+ * Skip this buffer rather than waiting.
+ */
+ continue;
+ }
+
+ passed_sz += HDR_GET_LSIZE(hdr);
+ if (l2arc_headroom != 0 && passed_sz > headroom) {
+ /*
+ * Searched too far.
+ */
+ mutex_exit(hash_lock);
+ break;
+ }
+
+ if (!l2arc_write_eligible(guid, hdr)) {
+ mutex_exit(hash_lock);
+ continue;
+ }
+
+ /*
+ * We rely on the L1 portion of the header below, so
+ * it's invalid for this header to have been evicted out
+ * of the ghost cache, prior to being written out. The
+ * ARC_FLAG_L2_WRITING bit ensures this won't happen.
+ */
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ ASSERT3U(HDR_GET_PSIZE(hdr), >, 0);
+ ASSERT3U(arc_hdr_size(hdr), >, 0);
+ ASSERT(hdr->b_l1hdr.b_pabd != NULL ||
+ HDR_HAS_RABD(hdr));
+ uint64_t psize = HDR_GET_PSIZE(hdr);
+ uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev,
+ psize);
+
+ if ((write_asize + asize) > target_sz) {
+ full = B_TRUE;
+ mutex_exit(hash_lock);
+ break;
+ }
+
+ /*
+ * We rely on the L1 portion of the header below, so
+ * it's invalid for this header to have been evicted out
+ * of the ghost cache, prior to being written out. The
+ * ARC_FLAG_L2_WRITING bit ensures this won't happen.
+ */
+ arc_hdr_set_flags(hdr, ARC_FLAG_L2_WRITING);
+ ASSERT(HDR_HAS_L1HDR(hdr));
+
+ ASSERT3U(HDR_GET_PSIZE(hdr), >, 0);
+ ASSERT(hdr->b_l1hdr.b_pabd != NULL ||
+ HDR_HAS_RABD(hdr));
+ ASSERT3U(arc_hdr_size(hdr), >, 0);
+
+ /*
+ * If this header has b_rabd, we can use this since it
+ * must always match the data exactly as it exists on
+ * disk. Otherwise, the L2ARC can normally use the
+ * hdr's data, but if we're sharing data between the
+ * hdr and one of its bufs, L2ARC needs its own copy of
+ * the data so that the ZIO below can't race with the
+ * buf consumer. To ensure that this copy will be
+ * available for the lifetime of the ZIO and be cleaned
+ * up afterwards, we add it to the l2arc_free_on_write
+ * queue. If we need to apply any transforms to the
+ * data (compression, encryption) we will also need the
+ * extra buffer.
+ */
+ if (HDR_HAS_RABD(hdr) && psize == asize) {
+ to_write = hdr->b_crypt_hdr.b_rabd;
+ } else if ((HDR_COMPRESSION_ENABLED(hdr) ||
+ HDR_GET_COMPRESS(hdr) == ZIO_COMPRESS_OFF) &&
+ !HDR_ENCRYPTED(hdr) && !HDR_SHARED_DATA(hdr) &&
+ psize == asize) {
+ to_write = hdr->b_l1hdr.b_pabd;
+ } else {
+ int ret;
+ arc_buf_contents_t type = arc_buf_type(hdr);
+
+ ret = l2arc_apply_transforms(spa, hdr, asize,
+ &to_write);
+ if (ret != 0) {
+ arc_hdr_clear_flags(hdr,
+ ARC_FLAG_L2_WRITING);
+ mutex_exit(hash_lock);
+ continue;
+ }
+
+ l2arc_free_abd_on_write(to_write, asize, type);
+ }
+
+ if (pio == NULL) {
+ /*
+ * Insert a dummy header on the buflist so
+ * l2arc_write_done() can find where the
+ * write buffers begin without searching.
+ */
+ mutex_enter(&dev->l2ad_mtx);
+ list_insert_head(&dev->l2ad_buflist, head);
+ mutex_exit(&dev->l2ad_mtx);
+
+ cb = kmem_alloc(
+ sizeof (l2arc_write_callback_t), KM_SLEEP);
+ cb->l2wcb_dev = dev;
+ cb->l2wcb_head = head;
+ /*
+ * Create a list to save allocated abd buffers
+ * for l2arc_log_blk_commit().
+ */
+ list_create(&cb->l2wcb_abd_list,
+ sizeof (l2arc_lb_abd_buf_t),
+ offsetof(l2arc_lb_abd_buf_t, node));
+ pio = zio_root(spa, l2arc_write_done, cb,
+ ZIO_FLAG_CANFAIL);
+ }
+
+ hdr->b_l2hdr.b_dev = dev;
+ hdr->b_l2hdr.b_hits = 0;
+
+ hdr->b_l2hdr.b_daddr = dev->l2ad_hand;
+ arc_hdr_set_flags(hdr, ARC_FLAG_HAS_L2HDR);
+
+ mutex_enter(&dev->l2ad_mtx);
+ list_insert_head(&dev->l2ad_buflist, hdr);
+ mutex_exit(&dev->l2ad_mtx);
+
+ (void) zfs_refcount_add_many(&dev->l2ad_alloc,
+ arc_hdr_size(hdr), hdr);
+
+ wzio = zio_write_phys(pio, dev->l2ad_vdev,
+ hdr->b_l2hdr.b_daddr, asize, to_write,
+ ZIO_CHECKSUM_OFF, NULL, hdr,
+ ZIO_PRIORITY_ASYNC_WRITE,
+ ZIO_FLAG_CANFAIL, B_FALSE);
+
+ write_lsize += HDR_GET_LSIZE(hdr);
+ DTRACE_PROBE2(l2arc__write, vdev_t *, dev->l2ad_vdev,
+ zio_t *, wzio);
+
+ write_psize += psize;
+ write_asize += asize;
+ dev->l2ad_hand += asize;
+ vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
+
+ mutex_exit(hash_lock);
+
+ /*
+ * Append buf info to current log and commit if full.
+ * arcstat_l2_{size,asize} kstats are updated
+ * internally.
+ */
+ if (l2arc_log_blk_insert(dev, hdr))
+ l2arc_log_blk_commit(dev, pio, cb);
+
+ zio_nowait(wzio);
+ }
+
+ multilist_sublist_unlock(mls);
+
+ if (full == B_TRUE)
+ break;
+ }
+
+ /* No buffers selected for writing? */
+ if (pio == NULL) {
+ ASSERT0(write_lsize);
+ ASSERT(!HDR_HAS_L1HDR(head));
+ kmem_cache_free(hdr_l2only_cache, head);
+
+ /*
+ * Although we did not write any buffers l2ad_evict may
+ * have advanced.
+ */
+ l2arc_dev_hdr_update(dev);
+
+ return (0);
+ }
+
+ if (!dev->l2ad_first)
+ ASSERT3U(dev->l2ad_hand, <=, dev->l2ad_evict);
+
+ ASSERT3U(write_asize, <=, target_sz);
+ ARCSTAT_BUMP(arcstat_l2_writes_sent);
+ ARCSTAT_INCR(arcstat_l2_write_bytes, write_psize);
+ ARCSTAT_INCR(arcstat_l2_lsize, write_lsize);
+ ARCSTAT_INCR(arcstat_l2_psize, write_psize);
+
+ dev->l2ad_writing = B_TRUE;
+ (void) zio_wait(pio);
+ dev->l2ad_writing = B_FALSE;
+
+ /*
+ * Update the device header after the zio completes as
+ * l2arc_write_done() may have updated the memory holding the log block
+ * pointers in the device header.
+ */
+ l2arc_dev_hdr_update(dev);
+
+ return (write_asize);
+}
+
+static boolean_t
+l2arc_hdr_limit_reached(void)
+{
+ int64_t s = aggsum_upper_bound(&astat_l2_hdr_size);
+
+ return (arc_reclaim_needed() || (s > arc_meta_limit * 3 / 4) ||
+ (s > (arc_warm ? arc_c : arc_c_max) * l2arc_meta_percent / 100));
+}
+
+/*
+ * This thread feeds the L2ARC at regular intervals. This is the beating
+ * heart of the L2ARC.
+ */
+/* ARGSUSED */
+static void
+l2arc_feed_thread(void *unused)
+{
+ callb_cpr_t cpr;
+ l2arc_dev_t *dev;
+ spa_t *spa;
+ uint64_t size, wrote;
+ clock_t begin, next = ddi_get_lbolt();
+ fstrans_cookie_t cookie;
+
+ CALLB_CPR_INIT(&cpr, &l2arc_feed_thr_lock, callb_generic_cpr, FTAG);
+
+ mutex_enter(&l2arc_feed_thr_lock);
+
+ cookie = spl_fstrans_mark();
+ while (l2arc_thread_exit == 0) {
+ CALLB_CPR_SAFE_BEGIN(&cpr);
+ (void) cv_timedwait_sig(&l2arc_feed_thr_cv,
+ &l2arc_feed_thr_lock, next);
+ CALLB_CPR_SAFE_END(&cpr, &l2arc_feed_thr_lock);
+ next = ddi_get_lbolt() + hz;
+
+ /*
+ * Quick check for L2ARC devices.
+ */
+ mutex_enter(&l2arc_dev_mtx);
+ if (l2arc_ndev == 0) {
+ mutex_exit(&l2arc_dev_mtx);
+ continue;
+ }
+ mutex_exit(&l2arc_dev_mtx);
+ begin = ddi_get_lbolt();
+
+ /*
+ * This selects the next l2arc device to write to, and in
+ * doing so the next spa to feed from: dev->l2ad_spa. This
+ * will return NULL if there are now no l2arc devices or if
+ * they are all faulted.
+ *
+ * If a device is returned, its spa's config lock is also
+ * held to prevent device removal. l2arc_dev_get_next()
+ * will grab and release l2arc_dev_mtx.
+ */
+ if ((dev = l2arc_dev_get_next()) == NULL)
+ continue;
+
+ spa = dev->l2ad_spa;
+ ASSERT3P(spa, !=, NULL);
+
+ /*
+ * If the pool is read-only then force the feed thread to
+ * sleep a little longer.
+ */
+ if (!spa_writeable(spa)) {
+ next = ddi_get_lbolt() + 5 * l2arc_feed_secs * hz;
+ spa_config_exit(spa, SCL_L2ARC, dev);
+ continue;
+ }
+
+ /*
+ * Avoid contributing to memory pressure.
+ */
+ if (l2arc_hdr_limit_reached()) {
+ ARCSTAT_BUMP(arcstat_l2_abort_lowmem);
+ spa_config_exit(spa, SCL_L2ARC, dev);
+ continue;
+ }
+
+ ARCSTAT_BUMP(arcstat_l2_feeds);
+
+ size = l2arc_write_size(dev);
+
+ /*
+ * Evict L2ARC buffers that will be overwritten.
+ */
+ l2arc_evict(dev, size, B_FALSE);
+
+ /*
+ * Write ARC buffers.
+ */
+ wrote = l2arc_write_buffers(spa, dev, size);
+
+ /*
+ * Calculate interval between writes.
+ */
+ next = l2arc_write_interval(begin, size, wrote);
+ spa_config_exit(spa, SCL_L2ARC, dev);
+ }
+ spl_fstrans_unmark(cookie);
+
+ l2arc_thread_exit = 0;
+ cv_broadcast(&l2arc_feed_thr_cv);
+ CALLB_CPR_EXIT(&cpr); /* drops l2arc_feed_thr_lock */
+ thread_exit();
+}
+
+boolean_t
+l2arc_vdev_present(vdev_t *vd)
+{
+ return (l2arc_vdev_get(vd) != NULL);
+}
+
+/*
+ * Returns the l2arc_dev_t associated with a particular vdev_t or NULL if
+ * the vdev_t isn't an L2ARC device.
+ */
+l2arc_dev_t *
+l2arc_vdev_get(vdev_t *vd)
+{
+ l2arc_dev_t *dev;
+
+ mutex_enter(&l2arc_dev_mtx);
+ for (dev = list_head(l2arc_dev_list); dev != NULL;
+ dev = list_next(l2arc_dev_list, dev)) {
+ if (dev->l2ad_vdev == vd)
+ break;
+ }
+ mutex_exit(&l2arc_dev_mtx);
+
+ return (dev);
+}
+
+/*
+ * Add a vdev for use by the L2ARC. By this point the spa has already
+ * validated the vdev and opened it.
+ */
+void
+l2arc_add_vdev(spa_t *spa, vdev_t *vd)
+{
+ l2arc_dev_t *adddev;
+ uint64_t l2dhdr_asize;
+
+ ASSERT(!l2arc_vdev_present(vd));
+
+ vdev_ashift_optimize(vd);
+
+ /*
+ * Create a new l2arc device entry.
+ */
+ adddev = vmem_zalloc(sizeof (l2arc_dev_t), KM_SLEEP);
+ adddev->l2ad_spa = spa;
+ adddev->l2ad_vdev = vd;
+ /* leave extra size for an l2arc device header */
+ l2dhdr_asize = adddev->l2ad_dev_hdr_asize =
+ MAX(sizeof (*adddev->l2ad_dev_hdr), 1 << vd->vdev_ashift);
+ adddev->l2ad_start = VDEV_LABEL_START_SIZE + l2dhdr_asize;
+ adddev->l2ad_end = VDEV_LABEL_START_SIZE + vdev_get_min_asize(vd);
+ ASSERT3U(adddev->l2ad_start, <, adddev->l2ad_end);
+ adddev->l2ad_hand = adddev->l2ad_start;
+ adddev->l2ad_evict = adddev->l2ad_start;
+ adddev->l2ad_first = B_TRUE;
+ adddev->l2ad_writing = B_FALSE;
+ adddev->l2ad_trim_all = B_FALSE;
+ list_link_init(&adddev->l2ad_node);
+ adddev->l2ad_dev_hdr = kmem_zalloc(l2dhdr_asize, KM_SLEEP);
+
+ mutex_init(&adddev->l2ad_mtx, NULL, MUTEX_DEFAULT, NULL);
+ /*
+ * This is a list of all ARC buffers that are still valid on the
+ * device.
+ */
+ list_create(&adddev->l2ad_buflist, sizeof (arc_buf_hdr_t),
+ offsetof(arc_buf_hdr_t, b_l2hdr.b_l2node));
+
+ /*
+ * This is a list of pointers to log blocks that are still present
+ * on the device.
+ */
+ list_create(&adddev->l2ad_lbptr_list, sizeof (l2arc_lb_ptr_buf_t),
+ offsetof(l2arc_lb_ptr_buf_t, node));
+
+ vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand);
+ zfs_refcount_create(&adddev->l2ad_alloc);
+ zfs_refcount_create(&adddev->l2ad_lb_asize);
+ zfs_refcount_create(&adddev->l2ad_lb_count);
+
+ /*
+ * Add device to global list
+ */
+ mutex_enter(&l2arc_dev_mtx);
+ list_insert_head(l2arc_dev_list, adddev);
+ atomic_inc_64(&l2arc_ndev);
+ mutex_exit(&l2arc_dev_mtx);
+
+ /*
+ * Decide if vdev is eligible for L2ARC rebuild
+ */
+ l2arc_rebuild_vdev(adddev->l2ad_vdev, B_FALSE);
+}
+
+void
+l2arc_rebuild_vdev(vdev_t *vd, boolean_t reopen)
+{
+ l2arc_dev_t *dev = NULL;
+ l2arc_dev_hdr_phys_t *l2dhdr;
+ uint64_t l2dhdr_asize;
+ spa_t *spa;
+ int err;
+ boolean_t l2dhdr_valid = B_TRUE;
+
+ dev = l2arc_vdev_get(vd);
+ ASSERT3P(dev, !=, NULL);
+ spa = dev->l2ad_spa;
+ l2dhdr = dev->l2ad_dev_hdr;
+ l2dhdr_asize = dev->l2ad_dev_hdr_asize;
+
+ /*
+ * The L2ARC has to hold at least the payload of one log block for
+ * them to be restored (persistent L2ARC). The payload of a log block
+ * depends on the amount of its log entries. We always write log blocks
+ * with 1022 entries. How many of them are committed or restored depends
+ * on the size of the L2ARC device. Thus the maximum payload of
+ * one log block is 1022 * SPA_MAXBLOCKSIZE = 16GB. If the L2ARC device
+ * is less than that, we reduce the amount of committed and restored
+ * log entries per block so as to enable persistence.
+ */
+ if (dev->l2ad_end < l2arc_rebuild_blocks_min_l2size) {
+ dev->l2ad_log_entries = 0;
+ } else {
+ dev->l2ad_log_entries = MIN((dev->l2ad_end -
+ dev->l2ad_start) >> SPA_MAXBLOCKSHIFT,
+ L2ARC_LOG_BLK_MAX_ENTRIES);
+ }
+
+ /*
+ * Read the device header, if an error is returned do not rebuild L2ARC.
+ */
+ if ((err = l2arc_dev_hdr_read(dev)) != 0)
+ l2dhdr_valid = B_FALSE;
+
+ if (l2dhdr_valid && dev->l2ad_log_entries > 0) {
+ /*
+ * If we are onlining a cache device (vdev_reopen) that was
+ * still present (l2arc_vdev_present()) and rebuild is enabled,
+ * we should evict all ARC buffers and pointers to log blocks
+ * and reclaim their space before restoring its contents to
+ * L2ARC.
+ */
+ if (reopen) {
+ if (!l2arc_rebuild_enabled) {
+ return;
+ } else {
+ l2arc_evict(dev, 0, B_TRUE);
+ /* start a new log block */
+ dev->l2ad_log_ent_idx = 0;
+ dev->l2ad_log_blk_payload_asize = 0;
+ dev->l2ad_log_blk_payload_start = 0;
+ }
+ }
+ /*
+ * Just mark the device as pending for a rebuild. We won't
+ * be starting a rebuild in line here as it would block pool
+ * import. Instead spa_load_impl will hand that off to an
+ * async task which will call l2arc_spa_rebuild_start.
+ */
+ dev->l2ad_rebuild = B_TRUE;
+ } else if (spa_writeable(spa)) {
+ /*
+ * In this case TRIM the whole device if l2arc_trim_ahead > 0,
+ * otherwise create a new header. We zero out the memory holding
+ * the header to reset dh_start_lbps. If we TRIM the whole
+ * device the new header will be written by
+ * vdev_trim_l2arc_thread() at the end of the TRIM to update the
+ * trim_state in the header too. When reading the header, if
+ * trim_state is not VDEV_TRIM_COMPLETE and l2arc_trim_ahead > 0
+ * we opt to TRIM the whole device again.
+ */
+ if (l2arc_trim_ahead > 0) {
+ dev->l2ad_trim_all = B_TRUE;
+ } else {
+ bzero(l2dhdr, l2dhdr_asize);
+ l2arc_dev_hdr_update(dev);
+ }
+ }
+}
+
+/*
+ * Remove a vdev from the L2ARC.
+ */
+void
+l2arc_remove_vdev(vdev_t *vd)
+{
+ l2arc_dev_t *remdev = NULL;
+
+ /*
+ * Find the device by vdev
+ */
+ remdev = l2arc_vdev_get(vd);
+ ASSERT3P(remdev, !=, NULL);
+
+ /*
+ * Cancel any ongoing or scheduled rebuild.
+ */
+ mutex_enter(&l2arc_rebuild_thr_lock);
+ if (remdev->l2ad_rebuild_began == B_TRUE) {
+ remdev->l2ad_rebuild_cancel = B_TRUE;
+ while (remdev->l2ad_rebuild == B_TRUE)
+ cv_wait(&l2arc_rebuild_thr_cv, &l2arc_rebuild_thr_lock);
+ }
+ mutex_exit(&l2arc_rebuild_thr_lock);
+
+ /*
+ * Remove device from global list
+ */
+ mutex_enter(&l2arc_dev_mtx);
+ list_remove(l2arc_dev_list, remdev);
+ l2arc_dev_last = NULL; /* may have been invalidated */
+ atomic_dec_64(&l2arc_ndev);
+ mutex_exit(&l2arc_dev_mtx);
+
+ /*
+ * Clear all buflists and ARC references. L2ARC device flush.
+ */
+ l2arc_evict(remdev, 0, B_TRUE);
+ list_destroy(&remdev->l2ad_buflist);
+ ASSERT(list_is_empty(&remdev->l2ad_lbptr_list));
+ list_destroy(&remdev->l2ad_lbptr_list);
+ mutex_destroy(&remdev->l2ad_mtx);
+ zfs_refcount_destroy(&remdev->l2ad_alloc);
+ zfs_refcount_destroy(&remdev->l2ad_lb_asize);
+ zfs_refcount_destroy(&remdev->l2ad_lb_count);
+ kmem_free(remdev->l2ad_dev_hdr, remdev->l2ad_dev_hdr_asize);
+ vmem_free(remdev, sizeof (l2arc_dev_t));
+}
+
+void
+l2arc_init(void)
+{
+ l2arc_thread_exit = 0;
+ l2arc_ndev = 0;
+ l2arc_writes_sent = 0;
+ l2arc_writes_done = 0;
+
+ mutex_init(&l2arc_feed_thr_lock, NULL, MUTEX_DEFAULT, NULL);
+ cv_init(&l2arc_feed_thr_cv, NULL, CV_DEFAULT, NULL);
+ mutex_init(&l2arc_rebuild_thr_lock, NULL, MUTEX_DEFAULT, NULL);
+ cv_init(&l2arc_rebuild_thr_cv, NULL, CV_DEFAULT, NULL);
+ mutex_init(&l2arc_dev_mtx, NULL, MUTEX_DEFAULT, NULL);
+ mutex_init(&l2arc_free_on_write_mtx, NULL, MUTEX_DEFAULT, NULL);
+
+ l2arc_dev_list = &L2ARC_dev_list;
+ l2arc_free_on_write = &L2ARC_free_on_write;
+ list_create(l2arc_dev_list, sizeof (l2arc_dev_t),
+ offsetof(l2arc_dev_t, l2ad_node));
+ list_create(l2arc_free_on_write, sizeof (l2arc_data_free_t),
+ offsetof(l2arc_data_free_t, l2df_list_node));
+}
+
+void
+l2arc_fini(void)
+{
+ mutex_destroy(&l2arc_feed_thr_lock);
+ cv_destroy(&l2arc_feed_thr_cv);
+ mutex_destroy(&l2arc_rebuild_thr_lock);
+ cv_destroy(&l2arc_rebuild_thr_cv);
+ mutex_destroy(&l2arc_dev_mtx);
+ mutex_destroy(&l2arc_free_on_write_mtx);
+
+ list_destroy(l2arc_dev_list);
+ list_destroy(l2arc_free_on_write);
+}
+
+void
+l2arc_start(void)
+{
+ if (!(spa_mode_global & SPA_MODE_WRITE))
+ return;
+
+ (void) thread_create(NULL, 0, l2arc_feed_thread, NULL, 0, &p0,
+ TS_RUN, defclsyspri);
+}
+
+void
+l2arc_stop(void)
+{
+ if (!(spa_mode_global & SPA_MODE_WRITE))
+ return;
+
+ mutex_enter(&l2arc_feed_thr_lock);
+ cv_signal(&l2arc_feed_thr_cv); /* kick thread out of startup */
+ l2arc_thread_exit = 1;
+ while (l2arc_thread_exit != 0)
+ cv_wait(&l2arc_feed_thr_cv, &l2arc_feed_thr_lock);
+ mutex_exit(&l2arc_feed_thr_lock);
+}
+
+/*
+ * Punches out rebuild threads for the L2ARC devices in a spa. This should
+ * be called after pool import from the spa async thread, since starting
+ * these threads directly from spa_import() will make them part of the
+ * "zpool import" context and delay process exit (and thus pool import).
+ */
+void
+l2arc_spa_rebuild_start(spa_t *spa)
+{
+ ASSERT(MUTEX_HELD(&spa_namespace_lock));
+
+ /*
+ * Locate the spa's l2arc devices and kick off rebuild threads.
+ */
+ for (int i = 0; i < spa->spa_l2cache.sav_count; i++) {
+ l2arc_dev_t *dev =
+ l2arc_vdev_get(spa->spa_l2cache.sav_vdevs[i]);
+ if (dev == NULL) {
+ /* Don't attempt a rebuild if the vdev is UNAVAIL */
+ continue;
+ }
+ mutex_enter(&l2arc_rebuild_thr_lock);
+ if (dev->l2ad_rebuild && !dev->l2ad_rebuild_cancel) {
+ dev->l2ad_rebuild_began = B_TRUE;
+ (void) thread_create(NULL, 0, l2arc_dev_rebuild_thread,
+ dev, 0, &p0, TS_RUN, minclsyspri);
+ }
+ mutex_exit(&l2arc_rebuild_thr_lock);
+ }
+}
+
+/*
+ * Main entry point for L2ARC rebuilding.
+ */
+static void
+l2arc_dev_rebuild_thread(void *arg)
+{
+ l2arc_dev_t *dev = arg;
+
+ VERIFY(!dev->l2ad_rebuild_cancel);
+ VERIFY(dev->l2ad_rebuild);
+ (void) l2arc_rebuild(dev);
+ mutex_enter(&l2arc_rebuild_thr_lock);
+ dev->l2ad_rebuild_began = B_FALSE;
+ dev->l2ad_rebuild = B_FALSE;
+ mutex_exit(&l2arc_rebuild_thr_lock);
+
+ thread_exit();
+}
+
+/*
+ * This function implements the actual L2ARC metadata rebuild. It:
+ * starts reading the log block chain and restores each block's contents
+ * to memory (reconstructing arc_buf_hdr_t's).
+ *
+ * Operation stops under any of the following conditions:
+ *
+ * 1) We reach the end of the log block chain.
+ * 2) We encounter *any* error condition (cksum errors, io errors)
+ */
+static int
+l2arc_rebuild(l2arc_dev_t *dev)
+{
+ vdev_t *vd = dev->l2ad_vdev;
+ spa_t *spa = vd->vdev_spa;
+ int err = 0;
+ l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
+ l2arc_log_blk_phys_t *this_lb, *next_lb;
+ zio_t *this_io = NULL, *next_io = NULL;
+ l2arc_log_blkptr_t lbps[2];
+ l2arc_lb_ptr_buf_t *lb_ptr_buf;
+ boolean_t lock_held;
+
+ this_lb = vmem_zalloc(sizeof (*this_lb), KM_SLEEP);
+ next_lb = vmem_zalloc(sizeof (*next_lb), KM_SLEEP);
+
+ /*
+ * We prevent device removal while issuing reads to the device,
+ * then during the rebuilding phases we drop this lock again so
+ * that a spa_unload or device remove can be initiated - this is
+ * safe, because the spa will signal us to stop before removing
+ * our device and wait for us to stop.
+ */
+ spa_config_enter(spa, SCL_L2ARC, vd, RW_READER);
+ lock_held = B_TRUE;
+
+ /*
+ * Retrieve the persistent L2ARC device state.
+ * L2BLK_GET_PSIZE returns aligned size for log blocks.
+ */
+ dev->l2ad_evict = MAX(l2dhdr->dh_evict, dev->l2ad_start);
+ dev->l2ad_hand = MAX(l2dhdr->dh_start_lbps[0].lbp_daddr +
+ L2BLK_GET_PSIZE((&l2dhdr->dh_start_lbps[0])->lbp_prop),
+ dev->l2ad_start);
+ dev->l2ad_first = !!(l2dhdr->dh_flags & L2ARC_DEV_HDR_EVICT_FIRST);
+
+ vd->vdev_trim_action_time = l2dhdr->dh_trim_action_time;
+ vd->vdev_trim_state = l2dhdr->dh_trim_state;
+
+ /*
+ * In case the zfs module parameter l2arc_rebuild_enabled is false
+ * we do not start the rebuild process.
+ */
+ if (!l2arc_rebuild_enabled)
+ goto out;
+
+ /* Prepare the rebuild process */
+ bcopy(l2dhdr->dh_start_lbps, lbps, sizeof (lbps));
+
+ /* Start the rebuild process */
+ for (;;) {
+ if (!l2arc_log_blkptr_valid(dev, &lbps[0]))
+ break;
+
+ if ((err = l2arc_log_blk_read(dev, &lbps[0], &lbps[1],
+ this_lb, next_lb, this_io, &next_io)) != 0)
+ goto out;
+
+ /*
+ * Our memory pressure valve. If the system is running low
+ * on memory, rather than swamping memory with new ARC buf
+ * hdrs, we opt not to rebuild the L2ARC. At this point,
+ * however, we have already set up our L2ARC dev to chain in
+ * new metadata log blocks, so the user may choose to offline/
+ * online the L2ARC dev at a later time (or re-import the pool)
+ * to reconstruct it (when there's less memory pressure).
+ */
+ if (l2arc_hdr_limit_reached()) {
+ ARCSTAT_BUMP(arcstat_l2_rebuild_abort_lowmem);
+ cmn_err(CE_NOTE, "System running low on memory, "
+ "aborting L2ARC rebuild.");
+ err = SET_ERROR(ENOMEM);
+ goto out;
+ }
+
+ spa_config_exit(spa, SCL_L2ARC, vd);
+ lock_held = B_FALSE;
+
+ /*
+ * Now that we know that the next_lb checks out alright, we
+ * can start reconstruction from this log block.
+ * L2BLK_GET_PSIZE returns aligned size for log blocks.
+ */
+ uint64_t asize = L2BLK_GET_PSIZE((&lbps[0])->lbp_prop);
+ l2arc_log_blk_restore(dev, this_lb, asize, lbps[0].lbp_daddr);
+
+ /*
+ * log block restored, include its pointer in the list of
+ * pointers to log blocks present in the L2ARC device.
+ */
+ lb_ptr_buf = kmem_zalloc(sizeof (l2arc_lb_ptr_buf_t), KM_SLEEP);
+ lb_ptr_buf->lb_ptr = kmem_zalloc(sizeof (l2arc_log_blkptr_t),
+ KM_SLEEP);
+ bcopy(&lbps[0], lb_ptr_buf->lb_ptr,
+ sizeof (l2arc_log_blkptr_t));
+ mutex_enter(&dev->l2ad_mtx);
+ list_insert_tail(&dev->l2ad_lbptr_list, lb_ptr_buf);
+ ARCSTAT_INCR(arcstat_l2_log_blk_asize, asize);
+ ARCSTAT_BUMP(arcstat_l2_log_blk_count);
+ zfs_refcount_add_many(&dev->l2ad_lb_asize, asize, lb_ptr_buf);
+ zfs_refcount_add(&dev->l2ad_lb_count, lb_ptr_buf);
+ mutex_exit(&dev->l2ad_mtx);
+ vdev_space_update(vd, asize, 0, 0);
+
+ /*
+ * Protection against loops of log blocks:
+ *
+ * l2ad_hand l2ad_evict
+ * V V
+ * l2ad_start |=======================================| l2ad_end
+ * -----|||----|||---|||----|||
+ * (3) (2) (1) (0)
+ * ---|||---|||----|||---|||
+ * (7) (6) (5) (4)
+ *
+ * In this situation the pointer of log block (4) passes
+ * l2arc_log_blkptr_valid() but the log block should not be
+ * restored as it is overwritten by the payload of log block
+ * (0). Only log blocks (0)-(3) should be restored. We check
+ * whether l2ad_evict lies in between the payload starting
+ * offset of the next log block (lbps[1].lbp_payload_start)
+ * and the payload starting offset of the present log block
+ * (lbps[0].lbp_payload_start). If true and this isn't the
+ * first pass, we are looping from the beginning and we should
+ * stop.
+ */
+ if (l2arc_range_check_overlap(lbps[1].lbp_payload_start,
+ lbps[0].lbp_payload_start, dev->l2ad_evict) &&
+ !dev->l2ad_first)
+ goto out;
+
+ for (;;) {
+ mutex_enter(&l2arc_rebuild_thr_lock);
+ if (dev->l2ad_rebuild_cancel) {
+ dev->l2ad_rebuild = B_FALSE;
+ cv_signal(&l2arc_rebuild_thr_cv);
+ mutex_exit(&l2arc_rebuild_thr_lock);
+ err = SET_ERROR(ECANCELED);
+ goto out;
+ }
+ mutex_exit(&l2arc_rebuild_thr_lock);
+ if (spa_config_tryenter(spa, SCL_L2ARC, vd,
+ RW_READER)) {
+ lock_held = B_TRUE;
+ break;
+ }
+ /*
+ * L2ARC config lock held by somebody in writer,
+ * possibly due to them trying to remove us. They'll
+ * likely to want us to shut down, so after a little
+ * delay, we check l2ad_rebuild_cancel and retry
+ * the lock again.
+ */
+ delay(1);
+ }
+
+ /*
+ * Continue with the next log block.
+ */
+ lbps[0] = lbps[1];
+ lbps[1] = this_lb->lb_prev_lbp;
+ PTR_SWAP(this_lb, next_lb);
+ this_io = next_io;
+ next_io = NULL;
+ }
+
+ if (this_io != NULL)
+ l2arc_log_blk_fetch_abort(this_io);
+out:
+ if (next_io != NULL)
+ l2arc_log_blk_fetch_abort(next_io);
+ vmem_free(this_lb, sizeof (*this_lb));
+ vmem_free(next_lb, sizeof (*next_lb));
+
+ if (!l2arc_rebuild_enabled) {
+ spa_history_log_internal(spa, "L2ARC rebuild", NULL,
+ "disabled");
+ } else if (err == 0 && zfs_refcount_count(&dev->l2ad_lb_count) > 0) {
+ ARCSTAT_BUMP(arcstat_l2_rebuild_success);
+ spa_history_log_internal(spa, "L2ARC rebuild", NULL,
+ "successful, restored %llu blocks",
+ (u_longlong_t)zfs_refcount_count(&dev->l2ad_lb_count));
+ } else if (err == 0 && zfs_refcount_count(&dev->l2ad_lb_count) == 0) {
+ /*
+ * No error but also nothing restored, meaning the lbps array
+ * in the device header points to invalid/non-present log
+ * blocks. Reset the header.
+ */
+ spa_history_log_internal(spa, "L2ARC rebuild", NULL,
+ "no valid log blocks");
+ bzero(l2dhdr, dev->l2ad_dev_hdr_asize);
+ l2arc_dev_hdr_update(dev);
+ } else if (err == ECANCELED) {
+ /*
+ * In case the rebuild was canceled do not log to spa history
+ * log as the pool may be in the process of being removed.
+ */
+ zfs_dbgmsg("L2ARC rebuild aborted, restored %llu blocks",
+ zfs_refcount_count(&dev->l2ad_lb_count));
+ } else if (err != 0) {
+ spa_history_log_internal(spa, "L2ARC rebuild", NULL,
+ "aborted, restored %llu blocks",
+ (u_longlong_t)zfs_refcount_count(&dev->l2ad_lb_count));
+ }
+
+ if (lock_held)
+ spa_config_exit(spa, SCL_L2ARC, vd);
+
+ return (err);
+}
+
+/*
+ * Attempts to read the device header on the provided L2ARC device and writes
+ * it to `hdr'. On success, this function returns 0, otherwise the appropriate
+ * error code is returned.
+ */
+static int
+l2arc_dev_hdr_read(l2arc_dev_t *dev)
+{
+ int err;
+ uint64_t guid;
+ l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
+ const uint64_t l2dhdr_asize = dev->l2ad_dev_hdr_asize;
+ abd_t *abd;
+
+ guid = spa_guid(dev->l2ad_vdev->vdev_spa);
+
+ abd = abd_get_from_buf(l2dhdr, l2dhdr_asize);
+
+ err = zio_wait(zio_read_phys(NULL, dev->l2ad_vdev,
+ VDEV_LABEL_START_SIZE, l2dhdr_asize, abd,
+ ZIO_CHECKSUM_LABEL, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
+ ZIO_FLAG_DONT_CACHE | ZIO_FLAG_CANFAIL |
+ ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY |
+ ZIO_FLAG_SPECULATIVE, B_FALSE));
+
+ abd_put(abd);
+
+ if (err != 0) {
+ ARCSTAT_BUMP(arcstat_l2_rebuild_abort_dh_errors);
+ zfs_dbgmsg("L2ARC IO error (%d) while reading device header, "
+ "vdev guid: %llu", err, dev->l2ad_vdev->vdev_guid);
+ return (err);
+ }
+
+ if (l2dhdr->dh_magic == BSWAP_64(L2ARC_DEV_HDR_MAGIC))
+ byteswap_uint64_array(l2dhdr, sizeof (*l2dhdr));
+
+ if (l2dhdr->dh_magic != L2ARC_DEV_HDR_MAGIC ||
+ l2dhdr->dh_spa_guid != guid ||
+ l2dhdr->dh_vdev_guid != dev->l2ad_vdev->vdev_guid ||
+ l2dhdr->dh_version != L2ARC_PERSISTENT_VERSION ||
+ l2dhdr->dh_log_entries != dev->l2ad_log_entries ||
+ l2dhdr->dh_end != dev->l2ad_end ||
+ !l2arc_range_check_overlap(dev->l2ad_start, dev->l2ad_end,
+ l2dhdr->dh_evict) ||
+ (l2dhdr->dh_trim_state != VDEV_TRIM_COMPLETE &&
+ l2arc_trim_ahead > 0)) {
+ /*
+ * Attempt to rebuild a device containing no actual dev hdr
+ * or containing a header from some other pool or from another
+ * version of persistent L2ARC.
+ */
+ ARCSTAT_BUMP(arcstat_l2_rebuild_abort_unsupported);
+ return (SET_ERROR(ENOTSUP));
+ }
+
+ return (0);
+}
+
+/*
+ * Reads L2ARC log blocks from storage and validates their contents.
+ *
+ * This function implements a simple fetcher to make sure that while
+ * we're processing one buffer the L2ARC is already fetching the next
+ * one in the chain.
+ *
+ * The arguments this_lp and next_lp point to the current and next log block
+ * address in the block chain. Similarly, this_lb and next_lb hold the
+ * l2arc_log_blk_phys_t's of the current and next L2ARC blk.
+ *
+ * The `this_io' and `next_io' arguments are used for block fetching.
+ * When issuing the first blk IO during rebuild, you should pass NULL for
+ * `this_io'. This function will then issue a sync IO to read the block and
+ * also issue an async IO to fetch the next block in the block chain. The
+ * fetched IO is returned in `next_io'. On subsequent calls to this
+ * function, pass the value returned in `next_io' from the previous call
+ * as `this_io' and a fresh `next_io' pointer to hold the next fetch IO.
+ * Prior to the call, you should initialize your `next_io' pointer to be
+ * NULL. If no fetch IO was issued, the pointer is left set at NULL.
+ *
+ * On success, this function returns 0, otherwise it returns an appropriate
+ * error code. On error the fetching IO is aborted and cleared before
+ * returning from this function. Therefore, if we return `success', the
+ * caller can assume that we have taken care of cleanup of fetch IOs.
+ */
+static int
+l2arc_log_blk_read(l2arc_dev_t *dev,
+ const l2arc_log_blkptr_t *this_lbp, const l2arc_log_blkptr_t *next_lbp,
+ l2arc_log_blk_phys_t *this_lb, l2arc_log_blk_phys_t *next_lb,
+ zio_t *this_io, zio_t **next_io)
+{
+ int err = 0;
+ zio_cksum_t cksum;
+ abd_t *abd = NULL;
+ uint64_t asize;
+
+ ASSERT(this_lbp != NULL && next_lbp != NULL);
+ ASSERT(this_lb != NULL && next_lb != NULL);
+ ASSERT(next_io != NULL && *next_io == NULL);
+ ASSERT(l2arc_log_blkptr_valid(dev, this_lbp));
+
+ /*
+ * Check to see if we have issued the IO for this log block in a
+ * previous run. If not, this is the first call, so issue it now.
+ */
+ if (this_io == NULL) {
+ this_io = l2arc_log_blk_fetch(dev->l2ad_vdev, this_lbp,
+ this_lb);
+ }
+
+ /*
+ * Peek to see if we can start issuing the next IO immediately.
+ */
+ if (l2arc_log_blkptr_valid(dev, next_lbp)) {
+ /*
+ * Start issuing IO for the next log block early - this
+ * should help keep the L2ARC device busy while we
+ * decompress and restore this log block.
+ */
+ *next_io = l2arc_log_blk_fetch(dev->l2ad_vdev, next_lbp,
+ next_lb);
+ }
+
+ /* Wait for the IO to read this log block to complete */
+ if ((err = zio_wait(this_io)) != 0) {
+ ARCSTAT_BUMP(arcstat_l2_rebuild_abort_io_errors);
+ zfs_dbgmsg("L2ARC IO error (%d) while reading log block, "
+ "offset: %llu, vdev guid: %llu", err, this_lbp->lbp_daddr,
+ dev->l2ad_vdev->vdev_guid);
+ goto cleanup;
+ }
+
+ /*
+ * Make sure the buffer checks out.
+ * L2BLK_GET_PSIZE returns aligned size for log blocks.
+ */
+ asize = L2BLK_GET_PSIZE((this_lbp)->lbp_prop);
+ fletcher_4_native(this_lb, asize, NULL, &cksum);
+ if (!ZIO_CHECKSUM_EQUAL(cksum, this_lbp->lbp_cksum)) {
+ ARCSTAT_BUMP(arcstat_l2_rebuild_abort_cksum_lb_errors);
+ zfs_dbgmsg("L2ARC log block cksum failed, offset: %llu, "
+ "vdev guid: %llu, l2ad_hand: %llu, l2ad_evict: %llu",
+ this_lbp->lbp_daddr, dev->l2ad_vdev->vdev_guid,
+ dev->l2ad_hand, dev->l2ad_evict);
+ err = SET_ERROR(ECKSUM);
+ goto cleanup;
+ }
+
+ /* Now we can take our time decoding this buffer */
+ switch (L2BLK_GET_COMPRESS((this_lbp)->lbp_prop)) {
+ case ZIO_COMPRESS_OFF:
+ break;
+ case ZIO_COMPRESS_LZ4:
+ abd = abd_alloc_for_io(asize, B_TRUE);
+ abd_copy_from_buf_off(abd, this_lb, 0, asize);
+ if ((err = zio_decompress_data(
+ L2BLK_GET_COMPRESS((this_lbp)->lbp_prop),
+ abd, this_lb, asize, sizeof (*this_lb), NULL)) != 0) {
+ err = SET_ERROR(EINVAL);
+ goto cleanup;
+ }
+ break;
+ default:
+ err = SET_ERROR(EINVAL);
+ goto cleanup;
+ }
+ if (this_lb->lb_magic == BSWAP_64(L2ARC_LOG_BLK_MAGIC))
+ byteswap_uint64_array(this_lb, sizeof (*this_lb));
+ if (this_lb->lb_magic != L2ARC_LOG_BLK_MAGIC) {
+ err = SET_ERROR(EINVAL);
+ goto cleanup;
+ }
+cleanup:
+ /* Abort an in-flight fetch I/O in case of error */
+ if (err != 0 && *next_io != NULL) {
+ l2arc_log_blk_fetch_abort(*next_io);
+ *next_io = NULL;
+ }
+ if (abd != NULL)
+ abd_free(abd);
+ return (err);
+}
+
+/*
+ * Restores the payload of a log block to ARC. This creates empty ARC hdr
+ * entries which only contain an l2arc hdr, essentially restoring the
+ * buffers to their L2ARC evicted state. This function also updates space
+ * usage on the L2ARC vdev to make sure it tracks restored buffers.
+ */
+static void
+l2arc_log_blk_restore(l2arc_dev_t *dev, const l2arc_log_blk_phys_t *lb,
+ uint64_t lb_asize, uint64_t lb_daddr)
+{
+ uint64_t size = 0, asize = 0;
+ uint64_t log_entries = dev->l2ad_log_entries;
+
+ /*
+ * Usually arc_adapt() is called only for data, not headers, but
+ * since we may allocate significant amount of memory here, let ARC
+ * grow its arc_c.
+ */
+ arc_adapt(log_entries * HDR_L2ONLY_SIZE, arc_l2c_only);
+
+ for (int i = log_entries - 1; i >= 0; i--) {
+ /*
+ * Restore goes in the reverse temporal direction to preserve
+ * correct temporal ordering of buffers in the l2ad_buflist.
+ * l2arc_hdr_restore also does a list_insert_tail instead of
+ * list_insert_head on the l2ad_buflist:
+ *
+ * LIST l2ad_buflist LIST
+ * HEAD <------ (time) ------ TAIL
+ * direction +-----+-----+-----+-----+-----+ direction
+ * of l2arc <== | buf | buf | buf | buf | buf | ===> of rebuild
+ * fill +-----+-----+-----+-----+-----+
+ * ^ ^
+ * | |
+ * | |
+ * l2arc_feed_thread l2arc_rebuild
+ * will place new bufs here restores bufs here
+ *
+ * During l2arc_rebuild() the device is not used by
+ * l2arc_feed_thread() as dev->l2ad_rebuild is set to true.
+ */
+ size += L2BLK_GET_LSIZE((&lb->lb_entries[i])->le_prop);
+ asize += vdev_psize_to_asize(dev->l2ad_vdev,
+ L2BLK_GET_PSIZE((&lb->lb_entries[i])->le_prop));
+ l2arc_hdr_restore(&lb->lb_entries[i], dev);
+ }
+
+ /*
+ * Record rebuild stats:
+ * size Logical size of restored buffers in the L2ARC
+ * asize Aligned size of restored buffers in the L2ARC
+ */
+ ARCSTAT_INCR(arcstat_l2_rebuild_size, size);
+ ARCSTAT_INCR(arcstat_l2_rebuild_asize, asize);
+ ARCSTAT_INCR(arcstat_l2_rebuild_bufs, log_entries);
+ ARCSTAT_F_AVG(arcstat_l2_log_blk_avg_asize, lb_asize);
+ ARCSTAT_F_AVG(arcstat_l2_data_to_meta_ratio, asize / lb_asize);
+ ARCSTAT_BUMP(arcstat_l2_rebuild_log_blks);
+}
+
+/*
+ * Restores a single ARC buf hdr from a log entry. The ARC buffer is put
+ * into a state indicating that it has been evicted to L2ARC.
+ */
+static void
+l2arc_hdr_restore(const l2arc_log_ent_phys_t *le, l2arc_dev_t *dev)
+{
+ arc_buf_hdr_t *hdr, *exists;
+ kmutex_t *hash_lock;
+ arc_buf_contents_t type = L2BLK_GET_TYPE((le)->le_prop);
+ uint64_t asize;
+
+ /*
+ * Do all the allocation before grabbing any locks, this lets us
+ * sleep if memory is full and we don't have to deal with failed
+ * allocations.
+ */
+ hdr = arc_buf_alloc_l2only(L2BLK_GET_LSIZE((le)->le_prop), type,
+ dev, le->le_dva, le->le_daddr,
+ L2BLK_GET_PSIZE((le)->le_prop), le->le_birth,
+ L2BLK_GET_COMPRESS((le)->le_prop), le->le_complevel,
+ L2BLK_GET_PROTECTED((le)->le_prop),
+ L2BLK_GET_PREFETCH((le)->le_prop));
+ asize = vdev_psize_to_asize(dev->l2ad_vdev,
+ L2BLK_GET_PSIZE((le)->le_prop));
+
+ /*
+ * vdev_space_update() has to be called before arc_hdr_destroy() to
+ * avoid underflow since the latter also calls the former.
+ */
+ vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
+
+ ARCSTAT_INCR(arcstat_l2_lsize, HDR_GET_LSIZE(hdr));
+ ARCSTAT_INCR(arcstat_l2_psize, HDR_GET_PSIZE(hdr));
+
+ mutex_enter(&dev->l2ad_mtx);
+ list_insert_tail(&dev->l2ad_buflist, hdr);
+ (void) zfs_refcount_add_many(&dev->l2ad_alloc, arc_hdr_size(hdr), hdr);
+ mutex_exit(&dev->l2ad_mtx);
+
+ exists = buf_hash_insert(hdr, &hash_lock);
+ if (exists) {
+ /* Buffer was already cached, no need to restore it. */
+ arc_hdr_destroy(hdr);
+ /*
+ * If the buffer is already cached, check whether it has
+ * L2ARC metadata. If not, enter them and update the flag.
+ * This is important is case of onlining a cache device, since
+ * we previously evicted all L2ARC metadata from ARC.
+ */
+ if (!HDR_HAS_L2HDR(exists)) {
+ arc_hdr_set_flags(exists, ARC_FLAG_HAS_L2HDR);
+ exists->b_l2hdr.b_dev = dev;
+ exists->b_l2hdr.b_daddr = le->le_daddr;
+ mutex_enter(&dev->l2ad_mtx);
+ list_insert_tail(&dev->l2ad_buflist, exists);
+ (void) zfs_refcount_add_many(&dev->l2ad_alloc,
+ arc_hdr_size(exists), exists);
+ mutex_exit(&dev->l2ad_mtx);
+ vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
+ ARCSTAT_INCR(arcstat_l2_lsize, HDR_GET_LSIZE(exists));
+ ARCSTAT_INCR(arcstat_l2_psize, HDR_GET_PSIZE(exists));
+ }
+ ARCSTAT_BUMP(arcstat_l2_rebuild_bufs_precached);
+ }
+
+ mutex_exit(hash_lock);
+}
+
+/*
+ * Starts an asynchronous read IO to read a log block. This is used in log
+ * block reconstruction to start reading the next block before we are done
+ * decoding and reconstructing the current block, to keep the l2arc device
+ * nice and hot with read IO to process.
+ * The returned zio will contain a newly allocated memory buffers for the IO
+ * data which should then be freed by the caller once the zio is no longer
+ * needed (i.e. due to it having completed). If you wish to abort this
+ * zio, you should do so using l2arc_log_blk_fetch_abort, which takes
+ * care of disposing of the allocated buffers correctly.
+ */
+static zio_t *
+l2arc_log_blk_fetch(vdev_t *vd, const l2arc_log_blkptr_t *lbp,
+ l2arc_log_blk_phys_t *lb)
+{
+ uint32_t asize;
+ zio_t *pio;
+ l2arc_read_callback_t *cb;
+
+ /* L2BLK_GET_PSIZE returns aligned size for log blocks */
+ asize = L2BLK_GET_PSIZE((lbp)->lbp_prop);
+ ASSERT(asize <= sizeof (l2arc_log_blk_phys_t));
+
+ cb = kmem_zalloc(sizeof (l2arc_read_callback_t), KM_SLEEP);
+ cb->l2rcb_abd = abd_get_from_buf(lb, asize);
+ pio = zio_root(vd->vdev_spa, l2arc_blk_fetch_done, cb,
+ ZIO_FLAG_DONT_CACHE | ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE |
+ ZIO_FLAG_DONT_RETRY);
+ (void) zio_nowait(zio_read_phys(pio, vd, lbp->lbp_daddr, asize,
+ cb->l2rcb_abd, ZIO_CHECKSUM_OFF, NULL, NULL,
+ ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_DONT_CACHE | ZIO_FLAG_CANFAIL |
+ ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY, B_FALSE));
+
+ return (pio);
+}
+
+/*
+ * Aborts a zio returned from l2arc_log_blk_fetch and frees the data
+ * buffers allocated for it.
+ */
+static void
+l2arc_log_blk_fetch_abort(zio_t *zio)
+{
+ (void) zio_wait(zio);
+}
+
+/*
+ * Creates a zio to update the device header on an l2arc device.
+ */
+void
+l2arc_dev_hdr_update(l2arc_dev_t *dev)
+{
+ l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
+ const uint64_t l2dhdr_asize = dev->l2ad_dev_hdr_asize;
+ abd_t *abd;
+ int err;
+
+ VERIFY(spa_config_held(dev->l2ad_spa, SCL_STATE_ALL, RW_READER));
+
+ l2dhdr->dh_magic = L2ARC_DEV_HDR_MAGIC;
+ l2dhdr->dh_version = L2ARC_PERSISTENT_VERSION;
+ l2dhdr->dh_spa_guid = spa_guid(dev->l2ad_vdev->vdev_spa);
+ l2dhdr->dh_vdev_guid = dev->l2ad_vdev->vdev_guid;
+ l2dhdr->dh_log_entries = dev->l2ad_log_entries;
+ l2dhdr->dh_evict = dev->l2ad_evict;
+ l2dhdr->dh_start = dev->l2ad_start;
+ l2dhdr->dh_end = dev->l2ad_end;
+ l2dhdr->dh_lb_asize = zfs_refcount_count(&dev->l2ad_lb_asize);
+ l2dhdr->dh_lb_count = zfs_refcount_count(&dev->l2ad_lb_count);
+ l2dhdr->dh_flags = 0;
+ l2dhdr->dh_trim_action_time = dev->l2ad_vdev->vdev_trim_action_time;
+ l2dhdr->dh_trim_state = dev->l2ad_vdev->vdev_trim_state;
+ if (dev->l2ad_first)
+ l2dhdr->dh_flags |= L2ARC_DEV_HDR_EVICT_FIRST;
+
+ abd = abd_get_from_buf(l2dhdr, l2dhdr_asize);
+
+ err = zio_wait(zio_write_phys(NULL, dev->l2ad_vdev,
+ VDEV_LABEL_START_SIZE, l2dhdr_asize, abd, ZIO_CHECKSUM_LABEL, NULL,
+ NULL, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_CANFAIL, B_FALSE));
+
+ abd_put(abd);
+
+ if (err != 0) {
+ zfs_dbgmsg("L2ARC IO error (%d) while writing device header, "
+ "vdev guid: %llu", err, dev->l2ad_vdev->vdev_guid);
+ }
+}
+
+/*
+ * Commits a log block to the L2ARC device. This routine is invoked from
+ * l2arc_write_buffers when the log block fills up.
+ * This function allocates some memory to temporarily hold the serialized
+ * buffer to be written. This is then released in l2arc_write_done.
+ */
+static void
+l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio, l2arc_write_callback_t *cb)
+{
+ l2arc_log_blk_phys_t *lb = &dev->l2ad_log_blk;
+ l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
+ uint64_t psize, asize;
+ zio_t *wzio;
+ l2arc_lb_abd_buf_t *abd_buf;
+ uint8_t *tmpbuf;
+ l2arc_lb_ptr_buf_t *lb_ptr_buf;
+
+ VERIFY3S(dev->l2ad_log_ent_idx, ==, dev->l2ad_log_entries);
+
+ tmpbuf = zio_buf_alloc(sizeof (*lb));
+ abd_buf = zio_buf_alloc(sizeof (*abd_buf));
+ abd_buf->abd = abd_get_from_buf(lb, sizeof (*lb));
+ lb_ptr_buf = kmem_zalloc(sizeof (l2arc_lb_ptr_buf_t), KM_SLEEP);
+ lb_ptr_buf->lb_ptr = kmem_zalloc(sizeof (l2arc_log_blkptr_t), KM_SLEEP);
+
+ /* link the buffer into the block chain */
+ lb->lb_prev_lbp = l2dhdr->dh_start_lbps[1];
+ lb->lb_magic = L2ARC_LOG_BLK_MAGIC;
+
+ /*
+ * l2arc_log_blk_commit() may be called multiple times during a single
+ * l2arc_write_buffers() call. Save the allocated abd buffers in a list
+ * so we can free them in l2arc_write_done() later on.
+ */
+ list_insert_tail(&cb->l2wcb_abd_list, abd_buf);
+
+ /* try to compress the buffer */
+ psize = zio_compress_data(ZIO_COMPRESS_LZ4,
+ abd_buf->abd, tmpbuf, sizeof (*lb), 0);
+
+ /* a log block is never entirely zero */
+ ASSERT(psize != 0);
+ asize = vdev_psize_to_asize(dev->l2ad_vdev, psize);
+ ASSERT(asize <= sizeof (*lb));
+
+ /*
+ * Update the start log block pointer in the device header to point
+ * to the log block we're about to write.
+ */
+ l2dhdr->dh_start_lbps[1] = l2dhdr->dh_start_lbps[0];
+ l2dhdr->dh_start_lbps[0].lbp_daddr = dev->l2ad_hand;
+ l2dhdr->dh_start_lbps[0].lbp_payload_asize =
+ dev->l2ad_log_blk_payload_asize;
+ l2dhdr->dh_start_lbps[0].lbp_payload_start =
+ dev->l2ad_log_blk_payload_start;
+ _NOTE(CONSTCOND)
+ L2BLK_SET_LSIZE(
+ (&l2dhdr->dh_start_lbps[0])->lbp_prop, sizeof (*lb));
+ L2BLK_SET_PSIZE(
+ (&l2dhdr->dh_start_lbps[0])->lbp_prop, asize);
+ L2BLK_SET_CHECKSUM(
+ (&l2dhdr->dh_start_lbps[0])->lbp_prop,
+ ZIO_CHECKSUM_FLETCHER_4);
+ if (asize < sizeof (*lb)) {
+ /* compression succeeded */
+ bzero(tmpbuf + psize, asize - psize);
+ L2BLK_SET_COMPRESS(
+ (&l2dhdr->dh_start_lbps[0])->lbp_prop,
+ ZIO_COMPRESS_LZ4);
+ } else {
+ /* compression failed */
+ bcopy(lb, tmpbuf, sizeof (*lb));
+ L2BLK_SET_COMPRESS(
+ (&l2dhdr->dh_start_lbps[0])->lbp_prop,
+ ZIO_COMPRESS_OFF);
+ }
+
+ /* checksum what we're about to write */
+ fletcher_4_native(tmpbuf, asize, NULL,
+ &l2dhdr->dh_start_lbps[0].lbp_cksum);
+
+ abd_put(abd_buf->abd);
+
+ /* perform the write itself */
+ abd_buf->abd = abd_get_from_buf(tmpbuf, sizeof (*lb));
+ abd_take_ownership_of_buf(abd_buf->abd, B_TRUE);
+ wzio = zio_write_phys(pio, dev->l2ad_vdev, dev->l2ad_hand,
+ asize, abd_buf->abd, ZIO_CHECKSUM_OFF, NULL, NULL,
+ ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_CANFAIL, B_FALSE);
+ DTRACE_PROBE2(l2arc__write, vdev_t *, dev->l2ad_vdev, zio_t *, wzio);
+ (void) zio_nowait(wzio);
+
+ dev->l2ad_hand += asize;
+ /*
+ * Include the committed log block's pointer in the list of pointers
+ * to log blocks present in the L2ARC device.
+ */
+ bcopy(&l2dhdr->dh_start_lbps[0], lb_ptr_buf->lb_ptr,
+ sizeof (l2arc_log_blkptr_t));
+ mutex_enter(&dev->l2ad_mtx);
+ list_insert_head(&dev->l2ad_lbptr_list, lb_ptr_buf);
+ ARCSTAT_INCR(arcstat_l2_log_blk_asize, asize);
+ ARCSTAT_BUMP(arcstat_l2_log_blk_count);
+ zfs_refcount_add_many(&dev->l2ad_lb_asize, asize, lb_ptr_buf);
+ zfs_refcount_add(&dev->l2ad_lb_count, lb_ptr_buf);
+ mutex_exit(&dev->l2ad_mtx);
+ vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
+
+ /* bump the kstats */
+ ARCSTAT_INCR(arcstat_l2_write_bytes, asize);
+ ARCSTAT_BUMP(arcstat_l2_log_blk_writes);
+ ARCSTAT_F_AVG(arcstat_l2_log_blk_avg_asize, asize);
+ ARCSTAT_F_AVG(arcstat_l2_data_to_meta_ratio,
+ dev->l2ad_log_blk_payload_asize / asize);
+
+ /* start a new log block */
+ dev->l2ad_log_ent_idx = 0;
+ dev->l2ad_log_blk_payload_asize = 0;
+ dev->l2ad_log_blk_payload_start = 0;
+}
+
+/*
+ * Validates an L2ARC log block address to make sure that it can be read
+ * from the provided L2ARC device.
+ */
+boolean_t
+l2arc_log_blkptr_valid(l2arc_dev_t *dev, const l2arc_log_blkptr_t *lbp)
+{
+ /* L2BLK_GET_PSIZE returns aligned size for log blocks */
+ uint64_t asize = L2BLK_GET_PSIZE((lbp)->lbp_prop);
+ uint64_t end = lbp->lbp_daddr + asize - 1;
+ uint64_t start = lbp->lbp_payload_start;
+ boolean_t evicted = B_FALSE;
+
+ /*
+ * A log block is valid if all of the following conditions are true:
+ * - it fits entirely (including its payload) between l2ad_start and
+ * l2ad_end
+ * - it has a valid size
+ * - neither the log block itself nor part of its payload was evicted
+ * by l2arc_evict():
+ *
+ * l2ad_hand l2ad_evict
+ * | | lbp_daddr
+ * | start | | end
+ * | | | | |
+ * V V V V V
+ * l2ad_start ============================================ l2ad_end
+ * --------------------------||||
+ * ^ ^
+ * | log block
+ * payload
+ */
+
+ evicted =
+ l2arc_range_check_overlap(start, end, dev->l2ad_hand) ||
+ l2arc_range_check_overlap(start, end, dev->l2ad_evict) ||
+ l2arc_range_check_overlap(dev->l2ad_hand, dev->l2ad_evict, start) ||
+ l2arc_range_check_overlap(dev->l2ad_hand, dev->l2ad_evict, end);
+
+ return (start >= dev->l2ad_start && end <= dev->l2ad_end &&
+ asize > 0 && asize <= sizeof (l2arc_log_blk_phys_t) &&
+ (!evicted || dev->l2ad_first));
+}
+
+/*
+ * Inserts ARC buffer header `hdr' into the current L2ARC log block on
+ * the device. The buffer being inserted must be present in L2ARC.
+ * Returns B_TRUE if the L2ARC log block is full and needs to be committed
+ * to L2ARC, or B_FALSE if it still has room for more ARC buffers.
+ */
+static boolean_t
+l2arc_log_blk_insert(l2arc_dev_t *dev, const arc_buf_hdr_t *hdr)
+{
+ l2arc_log_blk_phys_t *lb = &dev->l2ad_log_blk;
+ l2arc_log_ent_phys_t *le;
+
+ if (dev->l2ad_log_entries == 0)
+ return (B_FALSE);
+
+ int index = dev->l2ad_log_ent_idx++;
+
+ ASSERT3S(index, <, dev->l2ad_log_entries);
+ ASSERT(HDR_HAS_L2HDR(hdr));
+
+ le = &lb->lb_entries[index];
+ bzero(le, sizeof (*le));
+ le->le_dva = hdr->b_dva;
+ le->le_birth = hdr->b_birth;
+ le->le_daddr = hdr->b_l2hdr.b_daddr;
+ if (index == 0)
+ dev->l2ad_log_blk_payload_start = le->le_daddr;
+ L2BLK_SET_LSIZE((le)->le_prop, HDR_GET_LSIZE(hdr));
+ L2BLK_SET_PSIZE((le)->le_prop, HDR_GET_PSIZE(hdr));
+ L2BLK_SET_COMPRESS((le)->le_prop, HDR_GET_COMPRESS(hdr));
+ le->le_complevel = hdr->b_complevel;
+ L2BLK_SET_TYPE((le)->le_prop, hdr->b_type);
+ L2BLK_SET_PROTECTED((le)->le_prop, !!(HDR_PROTECTED(hdr)));
+ L2BLK_SET_PREFETCH((le)->le_prop, !!(HDR_PREFETCH(hdr)));
+
+ dev->l2ad_log_blk_payload_asize += vdev_psize_to_asize(dev->l2ad_vdev,
+ HDR_GET_PSIZE(hdr));
+
+ return (dev->l2ad_log_ent_idx == dev->l2ad_log_entries);
+}
+
+/*
+ * Checks whether a given L2ARC device address sits in a time-sequential
+ * range. The trick here is that the L2ARC is a rotary buffer, so we can't
+ * just do a range comparison, we need to handle the situation in which the
+ * range wraps around the end of the L2ARC device. Arguments:
+ * bottom -- Lower end of the range to check (written to earlier).
+ * top -- Upper end of the range to check (written to later).
+ * check -- The address for which we want to determine if it sits in
+ * between the top and bottom.
+ *
+ * The 3-way conditional below represents the following cases:
+ *
+ * bottom < top : Sequentially ordered case:
+ * <check>--------+-------------------+
+ * | (overlap here?) |
+ * L2ARC dev V V
+ * |---------------<bottom>============<top>--------------|
+ *
+ * bottom > top: Looped-around case:
+ * <check>--------+------------------+
+ * | (overlap here?) |
+ * L2ARC dev V V
+ * |===============<top>---------------<bottom>===========|
+ * ^ ^
+ * | (or here?) |
+ * +---------------+---------<check>
+ *
+ * top == bottom : Just a single address comparison.
+ */
+boolean_t
+l2arc_range_check_overlap(uint64_t bottom, uint64_t top, uint64_t check)
+{
+ if (bottom < top)
+ return (bottom <= check && check <= top);
+ else if (bottom > top)
+ return (check <= top || bottom <= check);
+ else
+ return (check == top);
+}
+
+EXPORT_SYMBOL(arc_buf_size);
+EXPORT_SYMBOL(arc_write);
+EXPORT_SYMBOL(arc_read);
+EXPORT_SYMBOL(arc_buf_info);
+EXPORT_SYMBOL(arc_getbuf_func);
+EXPORT_SYMBOL(arc_add_prune_callback);
+EXPORT_SYMBOL(arc_remove_prune_callback);
+
+/* BEGIN CSTYLED */
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, min, param_set_arc_long,
+ param_get_long, ZMOD_RW, "Min arc size");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, max, param_set_arc_long,
+ param_get_long, ZMOD_RW, "Max arc size");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, meta_limit, param_set_arc_long,
+ param_get_long, ZMOD_RW, "Metadata limit for arc size");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, meta_limit_percent,
+ param_set_arc_long, param_get_long, ZMOD_RW,
+ "Percent of arc size for arc meta limit");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, meta_min, param_set_arc_long,
+ param_get_long, ZMOD_RW, "Min arc metadata");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, meta_prune, INT, ZMOD_RW,
+ "Meta objects to scan for prune");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, meta_adjust_restarts, INT, ZMOD_RW,
+ "Limit number of restarts in arc_evict_meta");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, meta_strategy, INT, ZMOD_RW,
+ "Meta reclaim strategy");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, grow_retry, param_set_arc_int,
+ param_get_int, ZMOD_RW, "Seconds before growing arc size");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, p_dampener_disable, INT, ZMOD_RW,
+ "Disable arc_p adapt dampener");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, shrink_shift, param_set_arc_int,
+ param_get_int, ZMOD_RW, "log2(fraction of arc to reclaim)");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, pc_percent, UINT, ZMOD_RW,
+ "Percent of pagecache to reclaim arc to");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, p_min_shift, param_set_arc_int,
+ param_get_int, ZMOD_RW, "arc_c shift to calc min/max arc_p");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, average_blocksize, INT, ZMOD_RD,
+ "Target average block size");
+
+ZFS_MODULE_PARAM(zfs, zfs_, compressed_arc_enabled, INT, ZMOD_RW,
+ "Disable compressed arc buffers");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, min_prefetch_ms, param_set_arc_int,
+ param_get_int, ZMOD_RW, "Min life of prefetch block in ms");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, min_prescient_prefetch_ms,
+ param_set_arc_int, param_get_int, ZMOD_RW,
+ "Min life of prescient prefetched block in ms");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, write_max, ULONG, ZMOD_RW,
+ "Max write bytes per interval");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, write_boost, ULONG, ZMOD_RW,
+ "Extra write bytes during device warmup");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, headroom, ULONG, ZMOD_RW,
+ "Number of max device writes to precache");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, headroom_boost, ULONG, ZMOD_RW,
+ "Compressed l2arc_headroom multiplier");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, trim_ahead, ULONG, ZMOD_RW,
+ "TRIM ahead L2ARC write size multiplier");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, feed_secs, ULONG, ZMOD_RW,
+ "Seconds between L2ARC writing");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, feed_min_ms, ULONG, ZMOD_RW,
+ "Min feed interval in milliseconds");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, noprefetch, INT, ZMOD_RW,
+ "Skip caching prefetched buffers");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, feed_again, INT, ZMOD_RW,
+ "Turbo L2ARC warmup");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, norw, INT, ZMOD_RW,
+ "No reads during writes");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, meta_percent, INT, ZMOD_RW,
+ "Percent of ARC size allowed for L2ARC-only headers");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, rebuild_enabled, INT, ZMOD_RW,
+ "Rebuild the L2ARC when importing a pool");
+
+ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, rebuild_blocks_min_l2size, ULONG, ZMOD_RW,
+ "Min size in bytes to write rebuild log blocks in L2ARC");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, lotsfree_percent, param_set_arc_int,
+ param_get_int, ZMOD_RW, "System free memory I/O throttle in bytes");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, sys_free, param_set_arc_long,
+ param_get_long, ZMOD_RW, "System free memory target size in bytes");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, dnode_limit, param_set_arc_long,
+ param_get_long, ZMOD_RW, "Minimum bytes of dnodes in arc");
+
+ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, dnode_limit_percent,
+ param_set_arc_long, param_get_long, ZMOD_RW,
+ "Percent of ARC meta buffers for dnodes");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, dnode_reduce_percent, ULONG, ZMOD_RW,
+ "Percentage of excess dnodes to try to unpin");
+
+ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, eviction_pct, INT, ZMOD_RW,
+ "When full, ARC allocation waits for eviction of this % of alloc size");
+/* END CSTYLED */
diff --git a/sys/contrib/openzfs/module/zfs/blkptr.c b/sys/contrib/openzfs/module/zfs/blkptr.c
new file mode 100644
index 000000000000..aa09ded8dba3
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/blkptr.c
@@ -0,0 +1,153 @@
+/*
+ * CDDL HEADER START
+ *
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source. A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
+ */
+
+#include <sys/blkptr.h>
+#include <sys/zfs_context.h>
+#include <sys/zio.h>
+#include <sys/zio_compress.h>
+
+/*
+ * Embedded-data Block Pointers
+ *
+ * Normally, block pointers point (via their DVAs) to a block which holds data.
+ * If the data that we need to store is very small, this is an inefficient
+ * use of space, because a block must be at minimum 1 sector (typically 512
+ * bytes or 4KB). Additionally, reading these small blocks tends to generate
+ * more random reads.
+ *
+ * Embedded-data Block Pointers allow small pieces of data (the "payload",
+ * up to 112 bytes) to be stored in the block pointer itself, instead of
+ * being pointed to. The "Pointer" part of this name is a bit of a
+ * misnomer, as nothing is pointed to.
+ *
+ * BP_EMBEDDED_TYPE_DATA block pointers allow highly-compressible data to
+ * be embedded in the block pointer. The logic for this is handled in
+ * the SPA, by the zio pipeline. Therefore most code outside the zio
+ * pipeline doesn't need special-cases to handle these block pointers.
+ *
+ * See spa.h for details on the exact layout of embedded block pointers.
+ */
+
+void
+encode_embedded_bp_compressed(blkptr_t *bp, void *data,
+ enum zio_compress comp, int uncompressed_size, int compressed_size)
+{
+ uint64_t *bp64 = (uint64_t *)bp;
+ uint64_t w = 0;
+ uint8_t *data8 = data;
+
+ ASSERT3U(compressed_size, <=, BPE_PAYLOAD_SIZE);
+ ASSERT(uncompressed_size == compressed_size ||
+ comp != ZIO_COMPRESS_OFF);
+ ASSERT3U(comp, >=, ZIO_COMPRESS_OFF);
+ ASSERT3U(comp, <, ZIO_COMPRESS_FUNCTIONS);
+
+ bzero(bp, sizeof (*bp));
+ BP_SET_EMBEDDED(bp, B_TRUE);
+ BP_SET_COMPRESS(bp, comp);
+ BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
+ BPE_SET_LSIZE(bp, uncompressed_size);
+ BPE_SET_PSIZE(bp, compressed_size);
+
+ /*
+ * Encode the byte array into the words of the block pointer.
+ * First byte goes into low bits of first word (little endian).
+ */
+ for (int i = 0; i < compressed_size; i++) {
+ BF64_SET(w, (i % sizeof (w)) * NBBY, NBBY, data8[i]);
+ if (i % sizeof (w) == sizeof (w) - 1) {
+ /* we've reached the end of a word */
+ ASSERT3P(bp64, <, bp + 1);
+ *bp64 = w;
+ bp64++;
+ if (!BPE_IS_PAYLOADWORD(bp, bp64))
+ bp64++;
+ w = 0;
+ }
+ }
+ /* write last partial word */
+ if (bp64 < (uint64_t *)(bp + 1))
+ *bp64 = w;
+}
+
+/*
+ * buf must be at least BPE_GET_PSIZE(bp) bytes long (which will never be
+ * more than BPE_PAYLOAD_SIZE bytes).
+ */
+void
+decode_embedded_bp_compressed(const blkptr_t *bp, void *buf)
+{
+ int psize;
+ uint8_t *buf8 = buf;
+ uint64_t w = 0;
+ const uint64_t *bp64 = (const uint64_t *)bp;
+
+ ASSERT(BP_IS_EMBEDDED(bp));
+
+ psize = BPE_GET_PSIZE(bp);
+
+ /*
+ * Decode the words of the block pointer into the byte array.
+ * Low bits of first word are the first byte (little endian).
+ */
+ for (int i = 0; i < psize; i++) {
+ if (i % sizeof (w) == 0) {
+ /* beginning of a word */
+ ASSERT3P(bp64, <, bp + 1);
+ w = *bp64;
+ bp64++;
+ if (!BPE_IS_PAYLOADWORD(bp, bp64))
+ bp64++;
+ }
+ buf8[i] = BF64_GET(w, (i % sizeof (w)) * NBBY, NBBY);
+ }
+}
+
+/*
+ * Fill in the buffer with the (decompressed) payload of the embedded
+ * blkptr_t. Takes into account compression and byteorder (the payload is
+ * treated as a stream of bytes).
+ * Return 0 on success, or ENOSPC if it won't fit in the buffer.
+ */
+int
+decode_embedded_bp(const blkptr_t *bp, void *buf, int buflen)
+{
+ int lsize, psize;
+
+ ASSERT(BP_IS_EMBEDDED(bp));
+
+ lsize = BPE_GET_LSIZE(bp);
+ psize = BPE_GET_PSIZE(bp);
+
+ if (lsize > buflen)
+ return (SET_ERROR(ENOSPC));
+ ASSERT3U(lsize, ==, buflen);
+
+ if (BP_GET_COMPRESS(bp) != ZIO_COMPRESS_OFF) {
+ uint8_t dstbuf[BPE_PAYLOAD_SIZE];
+ decode_embedded_bp_compressed(bp, dstbuf);
+ VERIFY0(zio_decompress_data_buf(BP_GET_COMPRESS(bp),
+ dstbuf, buf, psize, buflen, NULL));
+ } else {
+ ASSERT3U(lsize, ==, psize);
+ decode_embedded_bp_compressed(bp, buf);
+ }
+
+ return (0);
+}
diff --git a/sys/contrib/openzfs/module/zfs/bplist.c b/sys/contrib/openzfs/module/zfs/bplist.c
new file mode 100644
index 000000000000..47ea364ef26f
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/bplist.c
@@ -0,0 +1,91 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
+ */
+
+#include <sys/bplist.h>
+#include <sys/zfs_context.h>
+
+
+void
+bplist_create(bplist_t *bpl)
+{
+ mutex_init(&bpl->bpl_lock, NULL, MUTEX_DEFAULT, NULL);
+ list_create(&bpl->bpl_list, sizeof (bplist_entry_t),
+ offsetof(bplist_entry_t, bpe_node));
+}
+
+void
+bplist_destroy(bplist_t *bpl)
+{
+ list_destroy(&bpl->bpl_list);
+ mutex_destroy(&bpl->bpl_lock);
+}
+
+void
+bplist_append(bplist_t *bpl, const blkptr_t *bp)
+{
+ bplist_entry_t *bpe = kmem_alloc(sizeof (*bpe), KM_SLEEP);
+
+ mutex_enter(&bpl->bpl_lock);
+ bpe->bpe_blk = *bp;
+ list_insert_tail(&bpl->bpl_list, bpe);
+ mutex_exit(&bpl->bpl_lock);
+}
+
+/*
+ * To aid debugging, we keep the most recently removed entry. This way if
+ * we are in the callback, we can easily locate the entry.
+ */
+static bplist_entry_t *bplist_iterate_last_removed;
+
+void
+bplist_iterate(bplist_t *bpl, bplist_itor_t *func, void *arg, dmu_tx_t *tx)
+{
+ bplist_entry_t *bpe;
+
+ mutex_enter(&bpl->bpl_lock);
+ while ((bpe = list_head(&bpl->bpl_list))) {
+ bplist_iterate_last_removed = bpe;
+ list_remove(&bpl->bpl_list, bpe);
+ mutex_exit(&bpl->bpl_lock);
+ func(arg, &bpe->bpe_blk, tx);
+ kmem_free(bpe, sizeof (*bpe));
+ mutex_enter(&bpl->bpl_lock);
+ }
+ mutex_exit(&bpl->bpl_lock);
+}
+
+void
+bplist_clear(bplist_t *bpl)
+{
+ bplist_entry_t *bpe;
+
+ mutex_enter(&bpl->bpl_lock);
+ while ((bpe = list_head(&bpl->bpl_list))) {
+ bplist_iterate_last_removed = bpe;
+ list_remove(&bpl->bpl_list, bpe);
+ kmem_free(bpe, sizeof (*bpe));
+ }
+ mutex_exit(&bpl->bpl_lock);
+}
diff --git a/sys/contrib/openzfs/module/zfs/bpobj.c b/sys/contrib/openzfs/module/zfs/bpobj.c
new file mode 100644
index 000000000000..e75ba5cccde6
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/bpobj.c
@@ -0,0 +1,943 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2017 Datto Inc.
+ */
+
+#include <sys/bpobj.h>
+#include <sys/zfs_context.h>
+#include <sys/zfs_refcount.h>
+#include <sys/dsl_pool.h>
+#include <sys/zfeature.h>
+#include <sys/zap.h>
+
+/*
+ * Return an empty bpobj, preferably the empty dummy one (dp_empty_bpobj).
+ */
+uint64_t
+bpobj_alloc_empty(objset_t *os, int blocksize, dmu_tx_t *tx)
+{
+ spa_t *spa = dmu_objset_spa(os);
+ dsl_pool_t *dp = dmu_objset_pool(os);
+
+ if (spa_feature_is_enabled(spa, SPA_FEATURE_EMPTY_BPOBJ)) {
+ if (!spa_feature_is_active(spa, SPA_FEATURE_EMPTY_BPOBJ)) {
+ ASSERT0(dp->dp_empty_bpobj);
+ dp->dp_empty_bpobj =
+ bpobj_alloc(os, SPA_OLD_MAXBLOCKSIZE, tx);
+ VERIFY(zap_add(os,
+ DMU_POOL_DIRECTORY_OBJECT,
+ DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
+ &dp->dp_empty_bpobj, tx) == 0);
+ }
+ spa_feature_incr(spa, SPA_FEATURE_EMPTY_BPOBJ, tx);
+ ASSERT(dp->dp_empty_bpobj != 0);
+ return (dp->dp_empty_bpobj);
+ } else {
+ return (bpobj_alloc(os, blocksize, tx));
+ }
+}
+
+void
+bpobj_decr_empty(objset_t *os, dmu_tx_t *tx)
+{
+ dsl_pool_t *dp = dmu_objset_pool(os);
+
+ spa_feature_decr(dmu_objset_spa(os), SPA_FEATURE_EMPTY_BPOBJ, tx);
+ if (!spa_feature_is_active(dmu_objset_spa(os),
+ SPA_FEATURE_EMPTY_BPOBJ)) {
+ VERIFY3U(0, ==, zap_remove(dp->dp_meta_objset,
+ DMU_POOL_DIRECTORY_OBJECT,
+ DMU_POOL_EMPTY_BPOBJ, tx));
+ VERIFY3U(0, ==, dmu_object_free(os, dp->dp_empty_bpobj, tx));
+ dp->dp_empty_bpobj = 0;
+ }
+}
+
+uint64_t
+bpobj_alloc(objset_t *os, int blocksize, dmu_tx_t *tx)
+{
+ int size;
+
+ if (spa_version(dmu_objset_spa(os)) < SPA_VERSION_BPOBJ_ACCOUNT)
+ size = BPOBJ_SIZE_V0;
+ else if (spa_version(dmu_objset_spa(os)) < SPA_VERSION_DEADLISTS)
+ size = BPOBJ_SIZE_V1;
+ else if (!spa_feature_is_active(dmu_objset_spa(os),
+ SPA_FEATURE_LIVELIST))
+ size = BPOBJ_SIZE_V2;
+ else
+ size = sizeof (bpobj_phys_t);
+
+ return (dmu_object_alloc(os, DMU_OT_BPOBJ, blocksize,
+ DMU_OT_BPOBJ_HDR, size, tx));
+}
+
+void
+bpobj_free(objset_t *os, uint64_t obj, dmu_tx_t *tx)
+{
+ int64_t i;
+ bpobj_t bpo;
+ dmu_object_info_t doi;
+ int epb;
+ dmu_buf_t *dbuf = NULL;
+
+ ASSERT(obj != dmu_objset_pool(os)->dp_empty_bpobj);
+ VERIFY3U(0, ==, bpobj_open(&bpo, os, obj));
+
+ mutex_enter(&bpo.bpo_lock);
+
+ if (!bpo.bpo_havesubobj || bpo.bpo_phys->bpo_subobjs == 0)
+ goto out;
+
+ VERIFY3U(0, ==, dmu_object_info(os, bpo.bpo_phys->bpo_subobjs, &doi));
+ epb = doi.doi_data_block_size / sizeof (uint64_t);
+
+ for (i = bpo.bpo_phys->bpo_num_subobjs - 1; i >= 0; i--) {
+ uint64_t *objarray;
+ uint64_t offset, blkoff;
+
+ offset = i * sizeof (uint64_t);
+ blkoff = P2PHASE(i, epb);
+
+ if (dbuf == NULL || dbuf->db_offset > offset) {
+ if (dbuf)
+ dmu_buf_rele(dbuf, FTAG);
+ VERIFY3U(0, ==, dmu_buf_hold(os,
+ bpo.bpo_phys->bpo_subobjs, offset, FTAG, &dbuf, 0));
+ }
+
+ ASSERT3U(offset, >=, dbuf->db_offset);
+ ASSERT3U(offset, <, dbuf->db_offset + dbuf->db_size);
+
+ objarray = dbuf->db_data;
+ bpobj_free(os, objarray[blkoff], tx);
+ }
+ if (dbuf) {
+ dmu_buf_rele(dbuf, FTAG);
+ dbuf = NULL;
+ }
+ VERIFY3U(0, ==, dmu_object_free(os, bpo.bpo_phys->bpo_subobjs, tx));
+
+out:
+ mutex_exit(&bpo.bpo_lock);
+ bpobj_close(&bpo);
+
+ VERIFY3U(0, ==, dmu_object_free(os, obj, tx));
+}
+
+int
+bpobj_open(bpobj_t *bpo, objset_t *os, uint64_t object)
+{
+ dmu_object_info_t doi;
+ int err;
+
+ err = dmu_object_info(os, object, &doi);
+ if (err)
+ return (err);
+
+ bzero(bpo, sizeof (*bpo));
+ mutex_init(&bpo->bpo_lock, NULL, MUTEX_DEFAULT, NULL);
+
+ ASSERT(bpo->bpo_dbuf == NULL);
+ ASSERT(bpo->bpo_phys == NULL);
+ ASSERT(object != 0);
+ ASSERT3U(doi.doi_type, ==, DMU_OT_BPOBJ);
+ ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_BPOBJ_HDR);
+
+ err = dmu_bonus_hold(os, object, bpo, &bpo->bpo_dbuf);
+ if (err)
+ return (err);
+
+ bpo->bpo_os = os;
+ bpo->bpo_object = object;
+ bpo->bpo_epb = doi.doi_data_block_size >> SPA_BLKPTRSHIFT;
+ bpo->bpo_havecomp = (doi.doi_bonus_size > BPOBJ_SIZE_V0);
+ bpo->bpo_havesubobj = (doi.doi_bonus_size > BPOBJ_SIZE_V1);
+ bpo->bpo_havefreed = (doi.doi_bonus_size > BPOBJ_SIZE_V2);
+ bpo->bpo_phys = bpo->bpo_dbuf->db_data;
+ return (0);
+}
+
+boolean_t
+bpobj_is_open(const bpobj_t *bpo)
+{
+ return (bpo->bpo_object != 0);
+}
+
+void
+bpobj_close(bpobj_t *bpo)
+{
+ /* Lame workaround for closing a bpobj that was never opened. */
+ if (bpo->bpo_object == 0)
+ return;
+
+ dmu_buf_rele(bpo->bpo_dbuf, bpo);
+ if (bpo->bpo_cached_dbuf != NULL)
+ dmu_buf_rele(bpo->bpo_cached_dbuf, bpo);
+ bpo->bpo_dbuf = NULL;
+ bpo->bpo_phys = NULL;
+ bpo->bpo_cached_dbuf = NULL;
+ bpo->bpo_object = 0;
+
+ mutex_destroy(&bpo->bpo_lock);
+}
+
+static boolean_t
+bpobj_is_empty_impl(bpobj_t *bpo)
+{
+ ASSERT(MUTEX_HELD(&bpo->bpo_lock));
+ return (bpo->bpo_phys->bpo_num_blkptrs == 0 &&
+ (!bpo->bpo_havesubobj || bpo->bpo_phys->bpo_num_subobjs == 0));
+}
+
+boolean_t
+bpobj_is_empty(bpobj_t *bpo)
+{
+ mutex_enter(&bpo->bpo_lock);
+ boolean_t is_empty = bpobj_is_empty_impl(bpo);
+ mutex_exit(&bpo->bpo_lock);
+ return (is_empty);
+}
+
+/*
+ * A recursive iteration of the bpobjs would be nice here but we run the risk
+ * of overflowing function stack space. Instead, find each subobj and add it
+ * to the head of our list so it can be scanned for subjobjs. Like a
+ * recursive implementation, the "deepest" subobjs will be freed first.
+ * When a subobj is found to have no additional subojs, free it.
+ */
+typedef struct bpobj_info {
+ bpobj_t *bpi_bpo;
+ /*
+ * This object is a subobj of bpi_parent,
+ * at bpi_index in its subobj array.
+ */
+ struct bpobj_info *bpi_parent;
+ uint64_t bpi_index;
+ /* How many of our subobj's are left to process. */
+ uint64_t bpi_unprocessed_subobjs;
+ /* True after having visited this bpo's directly referenced BPs. */
+ boolean_t bpi_visited;
+ list_node_t bpi_node;
+} bpobj_info_t;
+
+static bpobj_info_t *
+bpi_alloc(bpobj_t *bpo, bpobj_info_t *parent, uint64_t index)
+{
+ bpobj_info_t *bpi = kmem_zalloc(sizeof (bpobj_info_t), KM_SLEEP);
+ bpi->bpi_bpo = bpo;
+ bpi->bpi_parent = parent;
+ bpi->bpi_index = index;
+ if (bpo->bpo_havesubobj && bpo->bpo_phys->bpo_subobjs != 0) {
+ bpi->bpi_unprocessed_subobjs = bpo->bpo_phys->bpo_num_subobjs;
+ }
+ return (bpi);
+}
+
+/*
+ * Update bpobj and all of its parents with new space accounting.
+ */
+static void
+propagate_space_reduction(bpobj_info_t *bpi, int64_t freed,
+ int64_t comp_freed, int64_t uncomp_freed, dmu_tx_t *tx)
+{
+
+ for (; bpi != NULL; bpi = bpi->bpi_parent) {
+ bpobj_t *p = bpi->bpi_bpo;
+ ASSERT(dmu_buf_is_dirty(p->bpo_dbuf, tx));
+ p->bpo_phys->bpo_bytes -= freed;
+ ASSERT3S(p->bpo_phys->bpo_bytes, >=, 0);
+ if (p->bpo_havecomp) {
+ p->bpo_phys->bpo_comp -= comp_freed;
+ p->bpo_phys->bpo_uncomp -= uncomp_freed;
+ }
+ }
+}
+
+static int
+bpobj_iterate_blkptrs(bpobj_info_t *bpi, bpobj_itor_t func, void *arg,
+ int64_t start, dmu_tx_t *tx, boolean_t free)
+{
+ int err = 0;
+ int64_t freed = 0, comp_freed = 0, uncomp_freed = 0;
+ dmu_buf_t *dbuf = NULL;
+ bpobj_t *bpo = bpi->bpi_bpo;
+
+ for (int64_t i = bpo->bpo_phys->bpo_num_blkptrs - 1; i >= start; i--) {
+ uint64_t offset = i * sizeof (blkptr_t);
+ uint64_t blkoff = P2PHASE(i, bpo->bpo_epb);
+
+ if (dbuf == NULL || dbuf->db_offset > offset) {
+ if (dbuf)
+ dmu_buf_rele(dbuf, FTAG);
+ err = dmu_buf_hold(bpo->bpo_os, bpo->bpo_object,
+ offset, FTAG, &dbuf, 0);
+ if (err)
+ break;
+ }
+
+ ASSERT3U(offset, >=, dbuf->db_offset);
+ ASSERT3U(offset, <, dbuf->db_offset + dbuf->db_size);
+
+ blkptr_t *bparray = dbuf->db_data;
+ blkptr_t *bp = &bparray[blkoff];
+
+ boolean_t bp_freed = BP_GET_FREE(bp);
+ err = func(arg, bp, bp_freed, tx);
+ if (err)
+ break;
+
+ if (free) {
+ int sign = bp_freed ? -1 : +1;
+ spa_t *spa = dmu_objset_spa(bpo->bpo_os);
+ freed += sign * bp_get_dsize_sync(spa, bp);
+ comp_freed += sign * BP_GET_PSIZE(bp);
+ uncomp_freed += sign * BP_GET_UCSIZE(bp);
+ ASSERT(dmu_buf_is_dirty(bpo->bpo_dbuf, tx));
+ bpo->bpo_phys->bpo_num_blkptrs--;
+ ASSERT3S(bpo->bpo_phys->bpo_num_blkptrs, >=, 0);
+ if (bp_freed) {
+ ASSERT(bpo->bpo_havefreed);
+ bpo->bpo_phys->bpo_num_freed--;
+ ASSERT3S(bpo->bpo_phys->bpo_num_freed, >=, 0);
+ }
+ }
+ }
+ if (free) {
+ propagate_space_reduction(bpi, freed, comp_freed,
+ uncomp_freed, tx);
+ VERIFY0(dmu_free_range(bpo->bpo_os,
+ bpo->bpo_object,
+ bpo->bpo_phys->bpo_num_blkptrs * sizeof (blkptr_t),
+ DMU_OBJECT_END, tx));
+ }
+ if (dbuf) {
+ dmu_buf_rele(dbuf, FTAG);
+ dbuf = NULL;
+ }
+ return (err);
+}
+
+/*
+ * Given an initial bpo, start by freeing the BPs that are directly referenced
+ * by that bpo. If the bpo has subobjs, read in its last subobj and push the
+ * subobj to our stack. By popping items off our stack, eventually we will
+ * encounter a bpo that has no subobjs. We can free its bpobj_info_t, and if
+ * requested also free the now-empty bpo from disk and decrement
+ * its parent's subobj count. We continue popping each subobj from our stack,
+ * visiting its last subobj until they too have no more subobjs, and so on.
+ */
+static int
+bpobj_iterate_impl(bpobj_t *initial_bpo, bpobj_itor_t func, void *arg,
+ dmu_tx_t *tx, boolean_t free, uint64_t *bpobj_size)
+{
+ list_t stack;
+ bpobj_info_t *bpi;
+ int err = 0;
+
+ /*
+ * Create a "stack" for us to work with without worrying about
+ * stack overflows. Initialize it with the initial_bpo.
+ */
+ list_create(&stack, sizeof (bpobj_info_t),
+ offsetof(bpobj_info_t, bpi_node));
+ mutex_enter(&initial_bpo->bpo_lock);
+
+ if (bpobj_size != NULL)
+ *bpobj_size = initial_bpo->bpo_phys->bpo_num_blkptrs;
+
+ list_insert_head(&stack, bpi_alloc(initial_bpo, NULL, 0));
+
+ while ((bpi = list_head(&stack)) != NULL) {
+ bpobj_t *bpo = bpi->bpi_bpo;
+
+ ASSERT3P(bpo, !=, NULL);
+ ASSERT(MUTEX_HELD(&bpo->bpo_lock));
+ ASSERT(bpobj_is_open(bpo));
+
+ if (free)
+ dmu_buf_will_dirty(bpo->bpo_dbuf, tx);
+
+ if (bpi->bpi_visited == B_FALSE) {
+ err = bpobj_iterate_blkptrs(bpi, func, arg, 0, tx,
+ free);
+ bpi->bpi_visited = B_TRUE;
+ if (err != 0)
+ break;
+ }
+ /*
+ * We've finished with this bpo's directly-referenced BP's and
+ * it has no more unprocessed subobjs. We can free its
+ * bpobj_info_t (unless it is the topmost, initial_bpo).
+ * If we are freeing from disk, we can also do that.
+ */
+ if (bpi->bpi_unprocessed_subobjs == 0) {
+ /*
+ * If there are no entries, there should
+ * be no bytes.
+ */
+ if (bpobj_is_empty_impl(bpo)) {
+ ASSERT0(bpo->bpo_phys->bpo_bytes);
+ ASSERT0(bpo->bpo_phys->bpo_comp);
+ ASSERT0(bpo->bpo_phys->bpo_uncomp);
+ }
+
+ /* The initial_bpo has no parent and is not closed. */
+ if (bpi->bpi_parent != NULL) {
+ if (free) {
+ bpobj_t *p = bpi->bpi_parent->bpi_bpo;
+
+ ASSERT0(bpo->bpo_phys->bpo_num_blkptrs);
+ ASSERT3U(p->bpo_phys->bpo_num_subobjs,
+ >, 0);
+ ASSERT3U(bpi->bpi_index, ==,
+ p->bpo_phys->bpo_num_subobjs - 1);
+ ASSERT(dmu_buf_is_dirty(bpo->bpo_dbuf,
+ tx));
+
+ p->bpo_phys->bpo_num_subobjs--;
+
+ VERIFY0(dmu_free_range(p->bpo_os,
+ p->bpo_phys->bpo_subobjs,
+ bpi->bpi_index * sizeof (uint64_t),
+ sizeof (uint64_t), tx));
+
+ /* eliminate the empty subobj list */
+ if (bpo->bpo_havesubobj &&
+ bpo->bpo_phys->bpo_subobjs != 0) {
+ ASSERT0(bpo->bpo_phys->
+ bpo_num_subobjs);
+ err = dmu_object_free(
+ bpo->bpo_os,
+ bpo->bpo_phys->bpo_subobjs,
+ tx);
+ if (err)
+ break;
+ bpo->bpo_phys->bpo_subobjs = 0;
+ }
+ err = dmu_object_free(p->bpo_os,
+ bpo->bpo_object, tx);
+ if (err)
+ break;
+ }
+
+ mutex_exit(&bpo->bpo_lock);
+ bpobj_close(bpo);
+ kmem_free(bpo, sizeof (bpobj_t));
+ } else {
+ mutex_exit(&bpo->bpo_lock);
+ }
+
+ /*
+ * Finished processing this bpo. Unlock, and free
+ * our "stack" info.
+ */
+ list_remove_head(&stack);
+ kmem_free(bpi, sizeof (bpobj_info_t));
+ } else {
+ /*
+ * We have unprocessed subobjs. Process the next one.
+ */
+ ASSERT(bpo->bpo_havecomp);
+ ASSERT3P(bpobj_size, ==, NULL);
+
+ /* Add the last subobj to stack. */
+ int64_t i = bpi->bpi_unprocessed_subobjs - 1;
+ uint64_t offset = i * sizeof (uint64_t);
+
+ uint64_t obj_from_sublist;
+ err = dmu_read(bpo->bpo_os, bpo->bpo_phys->bpo_subobjs,
+ offset, sizeof (uint64_t), &obj_from_sublist,
+ DMU_READ_PREFETCH);
+ if (err)
+ break;
+ bpobj_t *sublist = kmem_alloc(sizeof (bpobj_t),
+ KM_SLEEP);
+
+ err = bpobj_open(sublist, bpo->bpo_os,
+ obj_from_sublist);
+ if (err)
+ break;
+
+ list_insert_head(&stack, bpi_alloc(sublist, bpi, i));
+ mutex_enter(&sublist->bpo_lock);
+ bpi->bpi_unprocessed_subobjs--;
+ }
+ }
+ /*
+ * Cleanup anything left on the "stack" after we left the loop.
+ * Every bpo on the stack is locked so we must remember to undo
+ * that now (in LIFO order).
+ */
+ while ((bpi = list_remove_head(&stack)) != NULL) {
+ bpobj_t *bpo = bpi->bpi_bpo;
+ ASSERT(err != 0);
+ ASSERT3P(bpo, !=, NULL);
+
+ mutex_exit(&bpo->bpo_lock);
+
+ /* do not free the initial_bpo */
+ if (bpi->bpi_parent != NULL) {
+ bpobj_close(bpi->bpi_bpo);
+ kmem_free(bpi->bpi_bpo, sizeof (bpobj_t));
+ }
+ kmem_free(bpi, sizeof (bpobj_info_t));
+ }
+
+ list_destroy(&stack);
+
+ return (err);
+}
+
+/*
+ * Iterate and remove the entries. If func returns nonzero, iteration
+ * will stop and that entry will not be removed.
+ */
+int
+bpobj_iterate(bpobj_t *bpo, bpobj_itor_t func, void *arg, dmu_tx_t *tx)
+{
+ return (bpobj_iterate_impl(bpo, func, arg, tx, B_TRUE, NULL));
+}
+
+/*
+ * Iterate the entries. If func returns nonzero, iteration will stop.
+ *
+ * If there are no subobjs:
+ *
+ * *bpobj_size can be used to return the number of block pointers in the
+ * bpobj. Note that this may be different from the number of block pointers
+ * that are iterated over, if iteration is terminated early (e.g. by the func
+ * returning nonzero).
+ *
+ * If there are concurrent (or subsequent) modifications to the bpobj then the
+ * returned *bpobj_size can be passed as "start" to
+ * livelist_bpobj_iterate_from_nofree() to iterate the newly added entries.
+ */
+int
+bpobj_iterate_nofree(bpobj_t *bpo, bpobj_itor_t func, void *arg,
+ uint64_t *bpobj_size)
+{
+ return (bpobj_iterate_impl(bpo, func, arg, NULL, B_FALSE, bpobj_size));
+}
+
+/*
+ * Iterate over the blkptrs in the bpobj beginning at index start. If func
+ * returns nonzero, iteration will stop. This is a livelist specific function
+ * since it assumes that there are no subobjs present.
+ */
+int
+livelist_bpobj_iterate_from_nofree(bpobj_t *bpo, bpobj_itor_t func, void *arg,
+ int64_t start)
+{
+ if (bpo->bpo_havesubobj)
+ VERIFY0(bpo->bpo_phys->bpo_subobjs);
+ bpobj_info_t *bpi = bpi_alloc(bpo, NULL, 0);
+ int err = bpobj_iterate_blkptrs(bpi, func, arg, start, NULL, B_FALSE);
+ kmem_free(bpi, sizeof (bpobj_info_t));
+ return (err);
+}
+
+/*
+ * Logically add subobj's contents to the parent bpobj.
+ *
+ * In the most general case, this is accomplished in constant time by adding
+ * a reference to subobj. This case is used when enqueuing a large subobj:
+ * +--------------+ +--------------+
+ * | bpobj |----------------------->| subobj list |
+ * +----+----+----+----+----+ +-----+-----+--+--+
+ * | bp | bp | bp | bp | bp | | obj | obj | obj |
+ * +----+----+----+----+----+ +-----+-----+-----+
+ *
+ * +--------------+ +--------------+
+ * | sub-bpobj |----------------------> | subsubobj |
+ * +----+----+----+----+---------+----+ +-----+-----+--+--------+-----+
+ * | bp | bp | bp | bp | ... | bp | | obj | obj | ... | obj |
+ * +----+----+----+----+---------+----+ +-----+-----+-----------+-----+
+ *
+ * Result: sub-bpobj added to parent's subobj list.
+ * +--------------+ +--------------+
+ * | bpobj |----------------------->| subobj list |
+ * +----+----+----+----+----+ +-----+-----+--+--+-----+
+ * | bp | bp | bp | bp | bp | | obj | obj | obj | OBJ |
+ * +----+----+----+----+----+ +-----+-----+-----+--|--+
+ * |
+ * /-----------------------------------------------------/
+ * v
+ * +--------------+ +--------------+
+ * | sub-bpobj |----------------------> | subsubobj |
+ * +----+----+----+----+---------+----+ +-----+-----+--+--------+-----+
+ * | bp | bp | bp | bp | ... | bp | | obj | obj | ... | obj |
+ * +----+----+----+----+---------+----+ +-----+-----+-----------+-----+
+ *
+ *
+ * In a common case, the subobj is small: its bp's and its list of subobj's
+ * are each stored in a single block. In this case we copy the subobj's
+ * contents to the parent:
+ * +--------------+ +--------------+
+ * | bpobj |----------------------->| subobj list |
+ * +----+----+----+----+----+ +-----+-----+--+--+
+ * | bp | bp | bp | bp | bp | | obj | obj | obj |
+ * +----+----+----+----+----+ +-----+-----+-----+
+ * ^ ^
+ * +--------------+ | +--------------+ |
+ * | sub-bpobj |---------^------------> | subsubobj | ^
+ * +----+----+----+ | +-----+-----+--+ |
+ * | BP | BP |-->-->-->-->-/ | OBJ | OBJ |-->-/
+ * +----+----+ +-----+-----+
+ *
+ * Result: subobj destroyed, contents copied to parent:
+ * +--------------+ +--------------+
+ * | bpobj |----------------------->| subobj list |
+ * +----+----+----+----+----+----+----+ +-----+-----+--+--+-----+-----+
+ * | bp | bp | bp | bp | bp | BP | BP | | obj | obj | obj | OBJ | OBJ |
+ * +----+----+----+----+----+----+----+ +-----+-----+-----+-----+-----+
+ *
+ *
+ * If the subobj has many BP's but few subobj's, we can copy the sub-subobj's
+ * but retain the sub-bpobj:
+ * +--------------+ +--------------+
+ * | bpobj |----------------------->| subobj list |
+ * +----+----+----+----+----+ +-----+-----+--+--+
+ * | bp | bp | bp | bp | bp | | obj | obj | obj |
+ * +----+----+----+----+----+ +-----+-----+-----+
+ * ^
+ * +--------------+ +--------------+ |
+ * | sub-bpobj |----------------------> | subsubobj | ^
+ * +----+----+----+----+---------+----+ +-----+-----+--+ |
+ * | bp | bp | bp | bp | ... | bp | | OBJ | OBJ |-->-/
+ * +----+----+----+----+---------+----+ +-----+-----+
+ *
+ * Result: sub-sub-bpobjs and subobj added to parent's subobj list.
+ * +--------------+ +--------------+
+ * | bpobj |-------------------->| subobj list |
+ * +----+----+----+----+----+ +-----+-----+--+--+-----+-----+------+
+ * | bp | bp | bp | bp | bp | | obj | obj | obj | OBJ | OBJ | OBJ* |
+ * +----+----+----+----+----+ +-----+-----+-----+-----+-----+--|---+
+ * |
+ * /--------------------------------------------------------------/
+ * v
+ * +--------------+
+ * | sub-bpobj |
+ * +----+----+----+----+---------+----+
+ * | bp | bp | bp | bp | ... | bp |
+ * +----+----+----+----+---------+----+
+ */
+void
+bpobj_enqueue_subobj(bpobj_t *bpo, uint64_t subobj, dmu_tx_t *tx)
+{
+ bpobj_t subbpo;
+ uint64_t used, comp, uncomp, subsubobjs;
+ boolean_t copy_subsub = B_TRUE;
+ boolean_t copy_bps = B_TRUE;
+
+ ASSERT(bpobj_is_open(bpo));
+ ASSERT(subobj != 0);
+ ASSERT(bpo->bpo_havesubobj);
+ ASSERT(bpo->bpo_havecomp);
+ ASSERT(bpo->bpo_object != dmu_objset_pool(bpo->bpo_os)->dp_empty_bpobj);
+
+ if (subobj == dmu_objset_pool(bpo->bpo_os)->dp_empty_bpobj) {
+ bpobj_decr_empty(bpo->bpo_os, tx);
+ return;
+ }
+
+ VERIFY3U(0, ==, bpobj_open(&subbpo, bpo->bpo_os, subobj));
+ VERIFY3U(0, ==, bpobj_space(&subbpo, &used, &comp, &uncomp));
+
+ if (bpobj_is_empty(&subbpo)) {
+ /* No point in having an empty subobj. */
+ bpobj_close(&subbpo);
+ bpobj_free(bpo->bpo_os, subobj, tx);
+ return;
+ }
+
+ mutex_enter(&bpo->bpo_lock);
+ dmu_buf_will_dirty(bpo->bpo_dbuf, tx);
+
+ dmu_object_info_t doi;
+
+ if (bpo->bpo_phys->bpo_subobjs != 0) {
+ ASSERT0(dmu_object_info(bpo->bpo_os, bpo->bpo_phys->bpo_subobjs,
+ &doi));
+ ASSERT3U(doi.doi_type, ==, DMU_OT_BPOBJ_SUBOBJ);
+ }
+
+ /*
+ * If subobj has only one block of subobjs, then move subobj's
+ * subobjs to bpo's subobj list directly. This reduces recursion in
+ * bpobj_iterate due to nested subobjs.
+ */
+ subsubobjs = subbpo.bpo_phys->bpo_subobjs;
+ if (subsubobjs != 0) {
+ VERIFY0(dmu_object_info(bpo->bpo_os, subsubobjs, &doi));
+ if (doi.doi_max_offset > doi.doi_data_block_size) {
+ copy_subsub = B_FALSE;
+ }
+ }
+
+ /*
+ * If, in addition to having only one block of subobj's, subobj has
+ * only one block of bp's, then move subobj's bp's to bpo's bp list
+ * directly. This reduces recursion in bpobj_iterate due to nested
+ * subobjs.
+ */
+ VERIFY3U(0, ==, dmu_object_info(bpo->bpo_os, subobj, &doi));
+ if (doi.doi_max_offset > doi.doi_data_block_size || !copy_subsub) {
+ copy_bps = B_FALSE;
+ }
+
+ if (copy_subsub && subsubobjs != 0) {
+ dmu_buf_t *subdb;
+ uint64_t numsubsub = subbpo.bpo_phys->bpo_num_subobjs;
+
+ VERIFY0(dmu_buf_hold(bpo->bpo_os, subsubobjs,
+ 0, FTAG, &subdb, 0));
+ /*
+ * Make sure that we are not asking dmu_write()
+ * to write more data than we have in our buffer.
+ */
+ VERIFY3U(subdb->db_size, >=,
+ numsubsub * sizeof (subobj));
+ if (bpo->bpo_phys->bpo_subobjs == 0) {
+ bpo->bpo_phys->bpo_subobjs =
+ dmu_object_alloc(bpo->bpo_os,
+ DMU_OT_BPOBJ_SUBOBJ, SPA_OLD_MAXBLOCKSIZE,
+ DMU_OT_NONE, 0, tx);
+ }
+ dmu_write(bpo->bpo_os, bpo->bpo_phys->bpo_subobjs,
+ bpo->bpo_phys->bpo_num_subobjs * sizeof (subobj),
+ numsubsub * sizeof (subobj), subdb->db_data, tx);
+ dmu_buf_rele(subdb, FTAG);
+ bpo->bpo_phys->bpo_num_subobjs += numsubsub;
+
+ dmu_buf_will_dirty(subbpo.bpo_dbuf, tx);
+ subbpo.bpo_phys->bpo_subobjs = 0;
+ VERIFY0(dmu_object_free(bpo->bpo_os, subsubobjs, tx));
+ }
+
+ if (copy_bps) {
+ dmu_buf_t *bps;
+ uint64_t numbps = subbpo.bpo_phys->bpo_num_blkptrs;
+
+ ASSERT(copy_subsub);
+ VERIFY0(dmu_buf_hold(bpo->bpo_os, subobj,
+ 0, FTAG, &bps, 0));
+
+ /*
+ * Make sure that we are not asking dmu_write()
+ * to write more data than we have in our buffer.
+ */
+ VERIFY3U(bps->db_size, >=, numbps * sizeof (blkptr_t));
+ dmu_write(bpo->bpo_os, bpo->bpo_object,
+ bpo->bpo_phys->bpo_num_blkptrs * sizeof (blkptr_t),
+ numbps * sizeof (blkptr_t),
+ bps->db_data, tx);
+ dmu_buf_rele(bps, FTAG);
+ bpo->bpo_phys->bpo_num_blkptrs += numbps;
+
+ bpobj_close(&subbpo);
+ VERIFY0(dmu_object_free(bpo->bpo_os, subobj, tx));
+ } else {
+ bpobj_close(&subbpo);
+ if (bpo->bpo_phys->bpo_subobjs == 0) {
+ bpo->bpo_phys->bpo_subobjs =
+ dmu_object_alloc(bpo->bpo_os,
+ DMU_OT_BPOBJ_SUBOBJ, SPA_OLD_MAXBLOCKSIZE,
+ DMU_OT_NONE, 0, tx);
+ }
+
+ dmu_write(bpo->bpo_os, bpo->bpo_phys->bpo_subobjs,
+ bpo->bpo_phys->bpo_num_subobjs * sizeof (subobj),
+ sizeof (subobj), &subobj, tx);
+ bpo->bpo_phys->bpo_num_subobjs++;
+ }
+
+ bpo->bpo_phys->bpo_bytes += used;
+ bpo->bpo_phys->bpo_comp += comp;
+ bpo->bpo_phys->bpo_uncomp += uncomp;
+ mutex_exit(&bpo->bpo_lock);
+
+}
+
+void
+bpobj_enqueue(bpobj_t *bpo, const blkptr_t *bp, boolean_t bp_freed,
+ dmu_tx_t *tx)
+{
+ blkptr_t stored_bp = *bp;
+ uint64_t offset;
+ int blkoff;
+ blkptr_t *bparray;
+
+ ASSERT(bpobj_is_open(bpo));
+ ASSERT(!BP_IS_HOLE(bp));
+ ASSERT(bpo->bpo_object != dmu_objset_pool(bpo->bpo_os)->dp_empty_bpobj);
+
+ if (BP_IS_EMBEDDED(bp)) {
+ /*
+ * The bpobj will compress better without the payload.
+ *
+ * Note that we store EMBEDDED bp's because they have an
+ * uncompressed size, which must be accounted for. An
+ * alternative would be to add their size to bpo_uncomp
+ * without storing the bp, but that would create additional
+ * complications: bpo_uncomp would be inconsistent with the
+ * set of BP's stored, and bpobj_iterate() wouldn't visit
+ * all the space accounted for in the bpobj.
+ */
+ bzero(&stored_bp, sizeof (stored_bp));
+ stored_bp.blk_prop = bp->blk_prop;
+ stored_bp.blk_birth = bp->blk_birth;
+ } else if (!BP_GET_DEDUP(bp)) {
+ /* The bpobj will compress better without the checksum */
+ bzero(&stored_bp.blk_cksum, sizeof (stored_bp.blk_cksum));
+ }
+
+ stored_bp.blk_fill = 0;
+ BP_SET_FREE(&stored_bp, bp_freed);
+
+ mutex_enter(&bpo->bpo_lock);
+
+ offset = bpo->bpo_phys->bpo_num_blkptrs * sizeof (stored_bp);
+ blkoff = P2PHASE(bpo->bpo_phys->bpo_num_blkptrs, bpo->bpo_epb);
+
+ if (bpo->bpo_cached_dbuf == NULL ||
+ offset < bpo->bpo_cached_dbuf->db_offset ||
+ offset >= bpo->bpo_cached_dbuf->db_offset +
+ bpo->bpo_cached_dbuf->db_size) {
+ if (bpo->bpo_cached_dbuf)
+ dmu_buf_rele(bpo->bpo_cached_dbuf, bpo);
+ VERIFY3U(0, ==, dmu_buf_hold(bpo->bpo_os, bpo->bpo_object,
+ offset, bpo, &bpo->bpo_cached_dbuf, 0));
+ }
+
+ dmu_buf_will_dirty(bpo->bpo_cached_dbuf, tx);
+ bparray = bpo->bpo_cached_dbuf->db_data;
+ bparray[blkoff] = stored_bp;
+
+ dmu_buf_will_dirty(bpo->bpo_dbuf, tx);
+ bpo->bpo_phys->bpo_num_blkptrs++;
+ int sign = bp_freed ? -1 : +1;
+ bpo->bpo_phys->bpo_bytes += sign *
+ bp_get_dsize_sync(dmu_objset_spa(bpo->bpo_os), bp);
+ if (bpo->bpo_havecomp) {
+ bpo->bpo_phys->bpo_comp += sign * BP_GET_PSIZE(bp);
+ bpo->bpo_phys->bpo_uncomp += sign * BP_GET_UCSIZE(bp);
+ }
+ if (bp_freed) {
+ ASSERT(bpo->bpo_havefreed);
+ bpo->bpo_phys->bpo_num_freed++;
+ }
+ mutex_exit(&bpo->bpo_lock);
+}
+
+struct space_range_arg {
+ spa_t *spa;
+ uint64_t mintxg;
+ uint64_t maxtxg;
+ uint64_t used;
+ uint64_t comp;
+ uint64_t uncomp;
+};
+
+/* ARGSUSED */
+static int
+space_range_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed, dmu_tx_t *tx)
+{
+ struct space_range_arg *sra = arg;
+
+ if (bp->blk_birth > sra->mintxg && bp->blk_birth <= sra->maxtxg) {
+ if (dsl_pool_sync_context(spa_get_dsl(sra->spa)))
+ sra->used += bp_get_dsize_sync(sra->spa, bp);
+ else
+ sra->used += bp_get_dsize(sra->spa, bp);
+ sra->comp += BP_GET_PSIZE(bp);
+ sra->uncomp += BP_GET_UCSIZE(bp);
+ }
+ return (0);
+}
+
+int
+bpobj_space(bpobj_t *bpo, uint64_t *usedp, uint64_t *compp, uint64_t *uncompp)
+{
+ ASSERT(bpobj_is_open(bpo));
+ mutex_enter(&bpo->bpo_lock);
+
+ *usedp = bpo->bpo_phys->bpo_bytes;
+ if (bpo->bpo_havecomp) {
+ *compp = bpo->bpo_phys->bpo_comp;
+ *uncompp = bpo->bpo_phys->bpo_uncomp;
+ mutex_exit(&bpo->bpo_lock);
+ return (0);
+ } else {
+ mutex_exit(&bpo->bpo_lock);
+ return (bpobj_space_range(bpo, 0, UINT64_MAX,
+ usedp, compp, uncompp));
+ }
+}
+
+/*
+ * Return the amount of space in the bpobj which is:
+ * mintxg < blk_birth <= maxtxg
+ */
+int
+bpobj_space_range(bpobj_t *bpo, uint64_t mintxg, uint64_t maxtxg,
+ uint64_t *usedp, uint64_t *compp, uint64_t *uncompp)
+{
+ struct space_range_arg sra = { 0 };
+ int err;
+
+ ASSERT(bpobj_is_open(bpo));
+
+ /*
+ * As an optimization, if they want the whole txg range, just
+ * get bpo_bytes rather than iterating over the bps.
+ */
+ if (mintxg < TXG_INITIAL && maxtxg == UINT64_MAX && bpo->bpo_havecomp)
+ return (bpobj_space(bpo, usedp, compp, uncompp));
+
+ sra.spa = dmu_objset_spa(bpo->bpo_os);
+ sra.mintxg = mintxg;
+ sra.maxtxg = maxtxg;
+
+ err = bpobj_iterate_nofree(bpo, space_range_cb, &sra, NULL);
+ *usedp = sra.used;
+ *compp = sra.comp;
+ *uncompp = sra.uncomp;
+ return (err);
+}
+
+/*
+ * A bpobj_itor_t to append blkptrs to a bplist. Note that while blkptrs in a
+ * bpobj are designated as free or allocated that information is not preserved
+ * in bplists.
+ */
+/* ARGSUSED */
+int
+bplist_append_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed,
+ dmu_tx_t *tx)
+{
+ bplist_t *bpl = arg;
+ bplist_append(bpl, bp);
+ return (0);
+}
diff --git a/sys/contrib/openzfs/module/zfs/bptree.c b/sys/contrib/openzfs/module/zfs/bptree.c
new file mode 100644
index 000000000000..1827a3c4e326
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/bptree.c
@@ -0,0 +1,303 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ */
+
+#include <sys/arc.h>
+#include <sys/bptree.h>
+#include <sys/dmu.h>
+#include <sys/dmu_objset.h>
+#include <sys/dmu_tx.h>
+#include <sys/dmu_traverse.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dsl_pool.h>
+#include <sys/dnode.h>
+#include <sys/spa.h>
+
+/*
+ * A bptree is a queue of root block pointers from destroyed datasets. When a
+ * dataset is destroyed its root block pointer is put on the end of the pool's
+ * bptree queue so the dataset's blocks can be freed asynchronously by
+ * dsl_scan_sync. This allows the delete operation to finish without traversing
+ * all the dataset's blocks.
+ *
+ * Note that while bt_begin and bt_end are only ever incremented in this code,
+ * they are effectively reset to 0 every time the entire bptree is freed because
+ * the bptree's object is destroyed and re-created.
+ */
+
+struct bptree_args {
+ bptree_phys_t *ba_phys; /* data in bonus buffer, dirtied if freeing */
+ boolean_t ba_free; /* true if freeing during traversal */
+
+ bptree_itor_t *ba_func; /* function to call for each blockpointer */
+ void *ba_arg; /* caller supplied argument to ba_func */
+ dmu_tx_t *ba_tx; /* caller supplied tx, NULL if not freeing */
+} bptree_args_t;
+
+uint64_t
+bptree_alloc(objset_t *os, dmu_tx_t *tx)
+{
+ uint64_t obj;
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+
+ obj = dmu_object_alloc(os, DMU_OTN_UINT64_METADATA,
+ SPA_OLD_MAXBLOCKSIZE, DMU_OTN_UINT64_METADATA,
+ sizeof (bptree_phys_t), tx);
+
+ /*
+ * Bonus buffer contents are already initialized to 0, but for
+ * readability we make it explicit.
+ */
+ VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
+ dmu_buf_will_dirty(db, tx);
+ bt = db->db_data;
+ bt->bt_begin = 0;
+ bt->bt_end = 0;
+ bt->bt_bytes = 0;
+ bt->bt_comp = 0;
+ bt->bt_uncomp = 0;
+ dmu_buf_rele(db, FTAG);
+
+ return (obj);
+}
+
+int
+bptree_free(objset_t *os, uint64_t obj, dmu_tx_t *tx)
+{
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+
+ VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
+ bt = db->db_data;
+ ASSERT3U(bt->bt_begin, ==, bt->bt_end);
+ ASSERT0(bt->bt_bytes);
+ ASSERT0(bt->bt_comp);
+ ASSERT0(bt->bt_uncomp);
+ dmu_buf_rele(db, FTAG);
+
+ return (dmu_object_free(os, obj, tx));
+}
+
+boolean_t
+bptree_is_empty(objset_t *os, uint64_t obj)
+{
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+ boolean_t rv;
+
+ VERIFY0(dmu_bonus_hold(os, obj, FTAG, &db));
+ bt = db->db_data;
+ rv = (bt->bt_begin == bt->bt_end);
+ dmu_buf_rele(db, FTAG);
+ return (rv);
+}
+
+void
+bptree_add(objset_t *os, uint64_t obj, blkptr_t *bp, uint64_t birth_txg,
+ uint64_t bytes, uint64_t comp, uint64_t uncomp, dmu_tx_t *tx)
+{
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+ bptree_entry_phys_t *bte;
+
+ /*
+ * bptree objects are in the pool mos, therefore they can only be
+ * modified in syncing context. Furthermore, this is only modified
+ * by the sync thread, so no locking is necessary.
+ */
+ ASSERT(dmu_tx_is_syncing(tx));
+
+ VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
+ bt = db->db_data;
+
+ bte = kmem_zalloc(sizeof (*bte), KM_SLEEP);
+ bte->be_birth_txg = birth_txg;
+ bte->be_bp = *bp;
+ dmu_write(os, obj, bt->bt_end * sizeof (*bte), sizeof (*bte), bte, tx);
+ kmem_free(bte, sizeof (*bte));
+
+ dmu_buf_will_dirty(db, tx);
+ bt->bt_end++;
+ bt->bt_bytes += bytes;
+ bt->bt_comp += comp;
+ bt->bt_uncomp += uncomp;
+ dmu_buf_rele(db, FTAG);
+}
+
+/* ARGSUSED */
+static int
+bptree_visit_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
+ const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
+{
+ int err;
+ struct bptree_args *ba = arg;
+
+ if (zb->zb_level == ZB_DNODE_LEVEL || BP_IS_HOLE(bp) ||
+ BP_IS_REDACTED(bp))
+ return (0);
+
+ err = ba->ba_func(ba->ba_arg, bp, ba->ba_tx);
+ if (err == 0 && ba->ba_free) {
+ ba->ba_phys->bt_bytes -= bp_get_dsize_sync(spa, bp);
+ ba->ba_phys->bt_comp -= BP_GET_PSIZE(bp);
+ ba->ba_phys->bt_uncomp -= BP_GET_UCSIZE(bp);
+ }
+ return (err);
+}
+
+/*
+ * If "free" is set:
+ * - It is assumed that "func" will be freeing the block pointers.
+ * - If "func" returns nonzero, the bookmark will be remembered and
+ * iteration will be restarted from this point on next invocation.
+ * - If an i/o error is encountered (e.g. "func" returns EIO or ECKSUM),
+ * bptree_iterate will remember the bookmark, continue traversing
+ * any additional entries, and return 0.
+ *
+ * If "free" is not set, traversal will stop and return an error if
+ * an i/o error is encountered.
+ *
+ * In either case, if zfs_free_leak_on_eio is set, i/o errors will be
+ * ignored and traversal will continue (i.e. TRAVERSE_HARD will be passed to
+ * traverse_dataset_destroyed()).
+ */
+int
+bptree_iterate(objset_t *os, uint64_t obj, boolean_t free, bptree_itor_t func,
+ void *arg, dmu_tx_t *tx)
+{
+ boolean_t ioerr = B_FALSE;
+ int err;
+ uint64_t i;
+ dmu_buf_t *db;
+ struct bptree_args ba;
+
+ ASSERT(!free || dmu_tx_is_syncing(tx));
+
+ err = dmu_bonus_hold(os, obj, FTAG, &db);
+ if (err != 0)
+ return (err);
+
+ if (free)
+ dmu_buf_will_dirty(db, tx);
+
+ ba.ba_phys = db->db_data;
+ ba.ba_free = free;
+ ba.ba_func = func;
+ ba.ba_arg = arg;
+ ba.ba_tx = tx;
+
+ err = 0;
+ for (i = ba.ba_phys->bt_begin; i < ba.ba_phys->bt_end; i++) {
+ bptree_entry_phys_t bte;
+ int flags = TRAVERSE_PREFETCH_METADATA | TRAVERSE_POST |
+ TRAVERSE_NO_DECRYPT;
+
+ err = dmu_read(os, obj, i * sizeof (bte), sizeof (bte),
+ &bte, DMU_READ_NO_PREFETCH);
+ if (err != 0)
+ break;
+
+ if (zfs_free_leak_on_eio)
+ flags |= TRAVERSE_HARD;
+ zfs_dbgmsg("bptree index %lld: traversing from min_txg=%lld "
+ "bookmark %lld/%lld/%lld/%lld",
+ (longlong_t)i,
+ (longlong_t)bte.be_birth_txg,
+ (longlong_t)bte.be_zb.zb_objset,
+ (longlong_t)bte.be_zb.zb_object,
+ (longlong_t)bte.be_zb.zb_level,
+ (longlong_t)bte.be_zb.zb_blkid);
+ err = traverse_dataset_destroyed(os->os_spa, &bte.be_bp,
+ bte.be_birth_txg, &bte.be_zb, flags,
+ bptree_visit_cb, &ba);
+ if (free) {
+ /*
+ * The callback has freed the visited block pointers.
+ * Record our traversal progress on disk, either by
+ * updating this record's bookmark, or by logically
+ * removing this record by advancing bt_begin.
+ */
+ if (err != 0) {
+ /* save bookmark for future resume */
+ ASSERT3U(bte.be_zb.zb_objset, ==,
+ ZB_DESTROYED_OBJSET);
+ ASSERT0(bte.be_zb.zb_level);
+ dmu_write(os, obj, i * sizeof (bte),
+ sizeof (bte), &bte, tx);
+ if (err == EIO || err == ECKSUM ||
+ err == ENXIO) {
+ /*
+ * Skip the rest of this tree and
+ * continue on to the next entry.
+ */
+ err = 0;
+ ioerr = B_TRUE;
+ } else {
+ break;
+ }
+ } else if (ioerr) {
+ /*
+ * This entry is finished, but there were
+ * i/o errors on previous entries, so we
+ * can't adjust bt_begin. Set this entry's
+ * be_birth_txg such that it will be
+ * treated as a no-op in future traversals.
+ */
+ bte.be_birth_txg = UINT64_MAX;
+ dmu_write(os, obj, i * sizeof (bte),
+ sizeof (bte), &bte, tx);
+ }
+
+ if (!ioerr) {
+ ba.ba_phys->bt_begin++;
+ (void) dmu_free_range(os, obj,
+ i * sizeof (bte), sizeof (bte), tx);
+ }
+ } else if (err != 0) {
+ break;
+ }
+ }
+
+ ASSERT(!free || err != 0 || ioerr ||
+ ba.ba_phys->bt_begin == ba.ba_phys->bt_end);
+
+ /* if all blocks are free there should be no used space */
+ if (ba.ba_phys->bt_begin == ba.ba_phys->bt_end) {
+ if (zfs_free_leak_on_eio) {
+ ba.ba_phys->bt_bytes = 0;
+ ba.ba_phys->bt_comp = 0;
+ ba.ba_phys->bt_uncomp = 0;
+ }
+
+ ASSERT0(ba.ba_phys->bt_bytes);
+ ASSERT0(ba.ba_phys->bt_comp);
+ ASSERT0(ba.ba_phys->bt_uncomp);
+ }
+
+ dmu_buf_rele(db, FTAG);
+
+ return (err);
+}
diff --git a/sys/contrib/openzfs/module/zfs/bqueue.c b/sys/contrib/openzfs/module/zfs/bqueue.c
new file mode 100644
index 000000000000..22539efc4e23
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/bqueue.c
@@ -0,0 +1,155 @@
+/*
+ * CDDL HEADER START
+ *
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source. A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2014, 2018 by Delphix. All rights reserved.
+ */
+
+#include <sys/bqueue.h>
+#include <sys/zfs_context.h>
+
+static inline bqueue_node_t *
+obj2node(bqueue_t *q, void *data)
+{
+ return ((bqueue_node_t *)((char *)data + q->bq_node_offset));
+}
+
+/*
+ * Initialize a blocking queue The maximum capacity of the queue is set to
+ * size. Types that are stored in a bqueue must contain a bqueue_node_t,
+ * and node_offset must be its offset from the start of the struct.
+ * fill_fraction is a performance tuning value; when the queue is full, any
+ * threads attempting to enqueue records will block. They will block until
+ * they're signaled, which will occur when the queue is at least 1/fill_fraction
+ * empty. Similar behavior occurs on dequeue; if the queue is empty, threads
+ * block. They will be signalled when the queue has 1/fill_fraction full, or
+ * when bqueue_flush is called. As a result, you must call bqueue_flush when
+ * you enqueue your final record on a thread, in case the dequeueing threads are
+ * currently blocked and that enqueue does not cause them to be awoken.
+ * Alternatively, this behavior can be disabled (causing signaling to happen
+ * immediately) by setting fill_fraction to any value larger than size.
+ * Return 0 on success, or -1 on failure.
+ */
+int
+bqueue_init(bqueue_t *q, uint64_t fill_fraction, uint64_t size,
+ size_t node_offset)
+{
+ if (fill_fraction == 0) {
+ return (-1);
+ }
+ list_create(&q->bq_list, node_offset + sizeof (bqueue_node_t),
+ node_offset + offsetof(bqueue_node_t, bqn_node));
+ cv_init(&q->bq_add_cv, NULL, CV_DEFAULT, NULL);
+ cv_init(&q->bq_pop_cv, NULL, CV_DEFAULT, NULL);
+ mutex_init(&q->bq_lock, NULL, MUTEX_DEFAULT, NULL);
+ q->bq_node_offset = node_offset;
+ q->bq_size = 0;
+ q->bq_maxsize = size;
+ q->bq_fill_fraction = fill_fraction;
+ return (0);
+}
+
+/*
+ * Destroy a blocking queue. This function asserts that there are no
+ * elements in the queue, and no one is blocked on the condition
+ * variables.
+ */
+void
+bqueue_destroy(bqueue_t *q)
+{
+ mutex_enter(&q->bq_lock);
+ ASSERT0(q->bq_size);
+ cv_destroy(&q->bq_add_cv);
+ cv_destroy(&q->bq_pop_cv);
+ list_destroy(&q->bq_list);
+ mutex_exit(&q->bq_lock);
+ mutex_destroy(&q->bq_lock);
+}
+
+static void
+bqueue_enqueue_impl(bqueue_t *q, void *data, uint64_t item_size,
+ boolean_t flush)
+{
+ ASSERT3U(item_size, >, 0);
+ ASSERT3U(item_size, <=, q->bq_maxsize);
+ mutex_enter(&q->bq_lock);
+ obj2node(q, data)->bqn_size = item_size;
+ while (q->bq_size + item_size > q->bq_maxsize) {
+ cv_wait_sig(&q->bq_add_cv, &q->bq_lock);
+ }
+ q->bq_size += item_size;
+ list_insert_tail(&q->bq_list, data);
+ if (q->bq_size >= q->bq_maxsize / q->bq_fill_fraction)
+ cv_signal(&q->bq_pop_cv);
+ if (flush)
+ cv_broadcast(&q->bq_pop_cv);
+ mutex_exit(&q->bq_lock);
+}
+
+/*
+ * Add data to q, consuming size units of capacity. If there is insufficient
+ * capacity to consume size units, block until capacity exists. Asserts size is
+ * > 0.
+ */
+void
+bqueue_enqueue(bqueue_t *q, void *data, uint64_t item_size)
+{
+ bqueue_enqueue_impl(q, data, item_size, B_FALSE);
+}
+
+/*
+ * Enqueue an entry, and then flush the queue. This forces the popping threads
+ * to wake up, even if we're below the fill fraction. We have this in a single
+ * function, rather than having a separate call, because it prevents race
+ * conditions between the enqueuing thread and the dequeueing thread, where the
+ * enqueueing thread will wake up the dequeueing thread, that thread will
+ * destroy the condvar before the enqueuing thread is done.
+ */
+void
+bqueue_enqueue_flush(bqueue_t *q, void *data, uint64_t item_size)
+{
+ bqueue_enqueue_impl(q, data, item_size, B_TRUE);
+}
+
+/*
+ * Take the first element off of q. If there are no elements on the queue, wait
+ * until one is put there. Return the removed element.
+ */
+void *
+bqueue_dequeue(bqueue_t *q)
+{
+ void *ret = NULL;
+ uint64_t item_size;
+ mutex_enter(&q->bq_lock);
+ while (q->bq_size == 0) {
+ cv_wait_sig(&q->bq_pop_cv, &q->bq_lock);
+ }
+ ret = list_remove_head(&q->bq_list);
+ ASSERT3P(ret, !=, NULL);
+ item_size = obj2node(q, ret)->bqn_size;
+ q->bq_size -= item_size;
+ if (q->bq_size <= q->bq_maxsize - (q->bq_maxsize / q->bq_fill_fraction))
+ cv_signal(&q->bq_add_cv);
+ mutex_exit(&q->bq_lock);
+ return (ret);
+}
+
+/*
+ * Returns true if the space used is 0.
+ */
+boolean_t
+bqueue_empty(bqueue_t *q)
+{
+ return (q->bq_size == 0);
+}
diff --git a/sys/contrib/openzfs/module/zfs/btree.c b/sys/contrib/openzfs/module/zfs/btree.c
new file mode 100644
index 000000000000..57b9dbbb2b50
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/btree.c
@@ -0,0 +1,2124 @@
+/*
+ * CDDL HEADER START
+ *
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source. A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2019 by Delphix. All rights reserved.
+ */
+
+#include <sys/btree.h>
+#include <sys/bitops.h>
+#include <sys/zfs_context.h>
+
+kmem_cache_t *zfs_btree_leaf_cache;
+
+/*
+ * Control the extent of the verification that occurs when zfs_btree_verify is
+ * called. Primarily used for debugging when extending the btree logic and
+ * functionality. As the intensity is increased, new verification steps are
+ * added. These steps are cumulative; intensity = 3 includes the intensity = 1
+ * and intensity = 2 steps as well.
+ *
+ * Intensity 1: Verify that the tree's height is consistent throughout.
+ * Intensity 2: Verify that a core node's children's parent pointers point
+ * to the core node.
+ * Intensity 3: Verify that the total number of elements in the tree matches the
+ * sum of the number of elements in each node. Also verifies that each node's
+ * count obeys the invariants (less than or equal to maximum value, greater than
+ * or equal to half the maximum minus one).
+ * Intensity 4: Verify that each element compares less than the element
+ * immediately after it and greater than the one immediately before it using the
+ * comparator function. For core nodes, also checks that each element is greater
+ * than the last element in the first of the two nodes it separates, and less
+ * than the first element in the second of the two nodes.
+ * Intensity 5: Verifies, if ZFS_DEBUG is defined, that all unused memory inside
+ * of each node is poisoned appropriately. Note that poisoning always occurs if
+ * ZFS_DEBUG is set, so it is safe to set the intensity to 5 during normal
+ * operation.
+ *
+ * Intensity 4 and 5 are particularly expensive to perform; the previous levels
+ * are a few memory operations per node, while these levels require multiple
+ * operations per element. In addition, when creating large btrees, these
+ * operations are called at every step, resulting in extremely slow operation
+ * (while the asymptotic complexity of the other steps is the same, the
+ * importance of the constant factors cannot be denied).
+ */
+int zfs_btree_verify_intensity = 0;
+
+/*
+ * A convenience function to silence warnings from memmove's return value and
+ * change argument order to src, dest.
+ */
+static void
+bmov(const void *src, void *dest, size_t size)
+{
+ (void) memmove(dest, src, size);
+}
+
+#ifdef _ILP32
+#define BTREE_POISON 0xabadb10c
+#else
+#define BTREE_POISON 0xabadb10cdeadbeef
+#endif
+
+static void
+zfs_btree_poison_node(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+#ifdef ZFS_DEBUG
+ size_t size = tree->bt_elem_size;
+ if (!hdr->bth_core) {
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)hdr;
+ (void) memset(leaf->btl_elems + hdr->bth_count * size, 0x0f,
+ BTREE_LEAF_SIZE - sizeof (zfs_btree_hdr_t) -
+ hdr->bth_count * size);
+ } else {
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ for (int i = hdr->bth_count + 1; i <= BTREE_CORE_ELEMS; i++) {
+ node->btc_children[i] =
+ (zfs_btree_hdr_t *)BTREE_POISON;
+ }
+ (void) memset(node->btc_elems + hdr->bth_count * size, 0x0f,
+ (BTREE_CORE_ELEMS - hdr->bth_count) * size);
+ }
+#endif
+}
+
+static inline void
+zfs_btree_poison_node_at(zfs_btree_t *tree, zfs_btree_hdr_t *hdr,
+ uint64_t offset)
+{
+#ifdef ZFS_DEBUG
+ size_t size = tree->bt_elem_size;
+ ASSERT3U(offset, >=, hdr->bth_count);
+ if (!hdr->bth_core) {
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)hdr;
+ (void) memset(leaf->btl_elems + offset * size, 0x0f, size);
+ } else {
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ node->btc_children[offset + 1] =
+ (zfs_btree_hdr_t *)BTREE_POISON;
+ (void) memset(node->btc_elems + offset * size, 0x0f, size);
+ }
+#endif
+}
+
+static inline void
+zfs_btree_verify_poison_at(zfs_btree_t *tree, zfs_btree_hdr_t *hdr,
+ uint64_t offset)
+{
+#ifdef ZFS_DEBUG
+ size_t size = tree->bt_elem_size;
+ uint8_t eval = 0x0f;
+ if (hdr->bth_core) {
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ zfs_btree_hdr_t *cval = (zfs_btree_hdr_t *)BTREE_POISON;
+ VERIFY3P(node->btc_children[offset + 1], ==, cval);
+ for (int i = 0; i < size; i++)
+ VERIFY3U(node->btc_elems[offset * size + i], ==, eval);
+ } else {
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)hdr;
+ for (int i = 0; i < size; i++)
+ VERIFY3U(leaf->btl_elems[offset * size + i], ==, eval);
+ }
+#endif
+}
+
+void
+zfs_btree_init(void)
+{
+ zfs_btree_leaf_cache = kmem_cache_create("zfs_btree_leaf_cache",
+ BTREE_LEAF_SIZE, 0, NULL, NULL, NULL, NULL,
+ NULL, 0);
+}
+
+void
+zfs_btree_fini(void)
+{
+ kmem_cache_destroy(zfs_btree_leaf_cache);
+}
+
+void
+zfs_btree_create(zfs_btree_t *tree, int (*compar) (const void *, const void *),
+ size_t size)
+{
+ /*
+ * We need a minimmum of 4 elements so that when we split a node we
+ * always have at least two elements in each node. This simplifies the
+ * logic in zfs_btree_bulk_finish, since it means the last leaf will
+ * always have a left sibling to share with (unless it's the root).
+ */
+ ASSERT3U(size, <=, (BTREE_LEAF_SIZE - sizeof (zfs_btree_hdr_t)) / 4);
+
+ bzero(tree, sizeof (*tree));
+ tree->bt_compar = compar;
+ tree->bt_elem_size = size;
+ tree->bt_height = -1;
+ tree->bt_bulk = NULL;
+}
+
+/*
+ * Find value in the array of elements provided. Uses a simple binary search.
+ */
+static void *
+zfs_btree_find_in_buf(zfs_btree_t *tree, uint8_t *buf, uint64_t nelems,
+ const void *value, zfs_btree_index_t *where)
+{
+ uint64_t max = nelems;
+ uint64_t min = 0;
+ while (max > min) {
+ uint64_t idx = (min + max) / 2;
+ uint8_t *cur = buf + idx * tree->bt_elem_size;
+ int comp = tree->bt_compar(cur, value);
+ if (comp == -1) {
+ min = idx + 1;
+ } else if (comp == 1) {
+ max = idx;
+ } else {
+ ASSERT0(comp);
+ where->bti_offset = idx;
+ where->bti_before = B_FALSE;
+ return (cur);
+ }
+ }
+
+ where->bti_offset = max;
+ where->bti_before = B_TRUE;
+ return (NULL);
+}
+
+/*
+ * Find the given value in the tree. where may be passed as null to use as a
+ * membership test or if the btree is being used as a map.
+ */
+void *
+zfs_btree_find(zfs_btree_t *tree, const void *value, zfs_btree_index_t *where)
+{
+ if (tree->bt_height == -1) {
+ if (where != NULL) {
+ where->bti_node = NULL;
+ where->bti_offset = 0;
+ }
+ ASSERT0(tree->bt_num_elems);
+ return (NULL);
+ }
+
+ /*
+ * If we're in bulk-insert mode, we check the last spot in the tree
+ * and the last leaf in the tree before doing the normal search,
+ * because for most workloads the vast majority of finds in
+ * bulk-insert mode are to insert new elements.
+ */
+ zfs_btree_index_t idx;
+ if (tree->bt_bulk != NULL) {
+ zfs_btree_leaf_t *last_leaf = tree->bt_bulk;
+ int compar = tree->bt_compar(last_leaf->btl_elems +
+ ((last_leaf->btl_hdr.bth_count - 1) * tree->bt_elem_size),
+ value);
+ if (compar < 0) {
+ /*
+ * If what they're looking for is after the last
+ * element, it's not in the tree.
+ */
+ if (where != NULL) {
+ where->bti_node = (zfs_btree_hdr_t *)last_leaf;
+ where->bti_offset =
+ last_leaf->btl_hdr.bth_count;
+ where->bti_before = B_TRUE;
+ }
+ return (NULL);
+ } else if (compar == 0) {
+ if (where != NULL) {
+ where->bti_node = (zfs_btree_hdr_t *)last_leaf;
+ where->bti_offset =
+ last_leaf->btl_hdr.bth_count - 1;
+ where->bti_before = B_FALSE;
+ }
+ return (last_leaf->btl_elems +
+ ((last_leaf->btl_hdr.bth_count - 1) *
+ tree->bt_elem_size));
+ }
+ if (tree->bt_compar(last_leaf->btl_elems, value) <= 0) {
+ /*
+ * If what they're looking for is after the first
+ * element in the last leaf, it's in the last leaf or
+ * it's not in the tree.
+ */
+ void *d = zfs_btree_find_in_buf(tree,
+ last_leaf->btl_elems, last_leaf->btl_hdr.bth_count,
+ value, &idx);
+
+ if (where != NULL) {
+ idx.bti_node = (zfs_btree_hdr_t *)last_leaf;
+ *where = idx;
+ }
+ return (d);
+ }
+ }
+
+ zfs_btree_core_t *node = NULL;
+ uint64_t child = 0;
+ uint64_t depth = 0;
+
+ /*
+ * Iterate down the tree, finding which child the value should be in
+ * by comparing with the separators.
+ */
+ for (node = (zfs_btree_core_t *)tree->bt_root; depth < tree->bt_height;
+ node = (zfs_btree_core_t *)node->btc_children[child], depth++) {
+ ASSERT3P(node, !=, NULL);
+ void *d = zfs_btree_find_in_buf(tree, node->btc_elems,
+ node->btc_hdr.bth_count, value, &idx);
+ EQUIV(d != NULL, !idx.bti_before);
+ if (d != NULL) {
+ if (where != NULL) {
+ idx.bti_node = (zfs_btree_hdr_t *)node;
+ *where = idx;
+ }
+ return (d);
+ }
+ ASSERT(idx.bti_before);
+ child = idx.bti_offset;
+ }
+
+ /*
+ * The value is in this leaf, or it would be if it were in the
+ * tree. Find its proper location and return it.
+ */
+ zfs_btree_leaf_t *leaf = (depth == 0 ?
+ (zfs_btree_leaf_t *)tree->bt_root : (zfs_btree_leaf_t *)node);
+ void *d = zfs_btree_find_in_buf(tree, leaf->btl_elems,
+ leaf->btl_hdr.bth_count, value, &idx);
+
+ if (where != NULL) {
+ idx.bti_node = (zfs_btree_hdr_t *)leaf;
+ *where = idx;
+ }
+
+ return (d);
+}
+
+/*
+ * To explain the following functions, it is useful to understand the four
+ * kinds of shifts used in btree operation. First, a shift is a movement of
+ * elements within a node. It is used to create gaps for inserting new
+ * elements and children, or cover gaps created when things are removed. A
+ * shift has two fundamental properties, each of which can be one of two
+ * values, making four types of shifts. There is the direction of the shift
+ * (left or right) and the shape of the shift (parallelogram or isoceles
+ * trapezoid (shortened to trapezoid hereafter)). The shape distinction only
+ * applies to shifts of core nodes.
+ *
+ * The names derive from the following imagining of the layout of a node:
+ *
+ * Elements: * * * * * * * ... * * *
+ * Children: * * * * * * * * ... * * *
+ *
+ * This layout follows from the fact that the elements act as separators
+ * between pairs of children, and that children root subtrees "below" the
+ * current node. A left and right shift are fairly self-explanatory; a left
+ * shift moves things to the left, while a right shift moves things to the
+ * right. A parallelogram shift is a shift with the same number of elements
+ * and children being moved, while a trapezoid shift is a shift that moves one
+ * more children than elements. An example follows:
+ *
+ * A parallelogram shift could contain the following:
+ * _______________
+ * \* * * * \ * * * ... * * *
+ * * \ * * * *\ * * * ... * * *
+ * ---------------
+ * A trapezoid shift could contain the following:
+ * ___________
+ * * / * * * \ * * * ... * * *
+ * * / * * * *\ * * * ... * * *
+ * ---------------
+ *
+ * Note that a parallelogram shift is always shaped like a "left-leaning"
+ * parallelogram, where the starting index of the children being moved is
+ * always one higher than the starting index of the elements being moved. No
+ * "right-leaning" parallelogram shifts are needed (shifts where the starting
+ * element index and starting child index being moved are the same) to achieve
+ * any btree operations, so we ignore them.
+ */
+
+enum bt_shift_shape {
+ BSS_TRAPEZOID,
+ BSS_PARALLELOGRAM
+};
+
+enum bt_shift_direction {
+ BSD_LEFT,
+ BSD_RIGHT
+};
+
+/*
+ * Shift elements and children in the provided core node by off spots. The
+ * first element moved is idx, and count elements are moved. The shape of the
+ * shift is determined by shape. The direction is determined by dir.
+ */
+static inline void
+bt_shift_core(zfs_btree_t *tree, zfs_btree_core_t *node, uint64_t idx,
+ uint64_t count, uint64_t off, enum bt_shift_shape shape,
+ enum bt_shift_direction dir)
+{
+ size_t size = tree->bt_elem_size;
+ ASSERT(node->btc_hdr.bth_core);
+
+ uint8_t *e_start = node->btc_elems + idx * size;
+ int sign = (dir == BSD_LEFT ? -1 : +1);
+ uint8_t *e_out = e_start + sign * off * size;
+ uint64_t e_count = count;
+ bmov(e_start, e_out, e_count * size);
+
+ zfs_btree_hdr_t **c_start = node->btc_children + idx +
+ (shape == BSS_TRAPEZOID ? 0 : 1);
+ zfs_btree_hdr_t **c_out = (dir == BSD_LEFT ? c_start - off :
+ c_start + off);
+ uint64_t c_count = count + (shape == BSS_TRAPEZOID ? 1 : 0);
+ bmov(c_start, c_out, c_count * sizeof (*c_start));
+}
+
+/*
+ * Shift elements and children in the provided core node left by one spot.
+ * The first element moved is idx, and count elements are moved. The
+ * shape of the shift is determined by trap; true if the shift is a trapezoid,
+ * false if it is a parallelogram.
+ */
+static inline void
+bt_shift_core_left(zfs_btree_t *tree, zfs_btree_core_t *node, uint64_t idx,
+ uint64_t count, enum bt_shift_shape shape)
+{
+ bt_shift_core(tree, node, idx, count, 1, shape, BSD_LEFT);
+}
+
+/*
+ * Shift elements and children in the provided core node right by one spot.
+ * Starts with elements[idx] and children[idx] and one more child than element.
+ */
+static inline void
+bt_shift_core_right(zfs_btree_t *tree, zfs_btree_core_t *node, uint64_t idx,
+ uint64_t count, enum bt_shift_shape shape)
+{
+ bt_shift_core(tree, node, idx, count, 1, shape, BSD_RIGHT);
+}
+
+/*
+ * Shift elements and children in the provided leaf node by off spots.
+ * The first element moved is idx, and count elements are moved. The direction
+ * is determined by left.
+ */
+static inline void
+bt_shift_leaf(zfs_btree_t *tree, zfs_btree_leaf_t *node, uint64_t idx,
+ uint64_t count, uint64_t off, enum bt_shift_direction dir)
+{
+ size_t size = tree->bt_elem_size;
+ ASSERT(!node->btl_hdr.bth_core);
+
+ uint8_t *start = node->btl_elems + idx * size;
+ int sign = (dir == BSD_LEFT ? -1 : +1);
+ uint8_t *out = start + sign * off * size;
+ bmov(start, out, count * size);
+}
+
+static inline void
+bt_shift_leaf_right(zfs_btree_t *tree, zfs_btree_leaf_t *leaf, uint64_t idx,
+ uint64_t count)
+{
+ bt_shift_leaf(tree, leaf, idx, count, 1, BSD_RIGHT);
+}
+
+static inline void
+bt_shift_leaf_left(zfs_btree_t *tree, zfs_btree_leaf_t *leaf, uint64_t idx,
+ uint64_t count)
+{
+ bt_shift_leaf(tree, leaf, idx, count, 1, BSD_LEFT);
+}
+
+/*
+ * Move children and elements from one core node to another. The shape
+ * parameter behaves the same as it does in the shift logic.
+ */
+static inline void
+bt_transfer_core(zfs_btree_t *tree, zfs_btree_core_t *source, uint64_t sidx,
+ uint64_t count, zfs_btree_core_t *dest, uint64_t didx,
+ enum bt_shift_shape shape)
+{
+ size_t size = tree->bt_elem_size;
+ ASSERT(source->btc_hdr.bth_core);
+ ASSERT(dest->btc_hdr.bth_core);
+
+ bmov(source->btc_elems + sidx * size, dest->btc_elems + didx * size,
+ count * size);
+
+ uint64_t c_count = count + (shape == BSS_TRAPEZOID ? 1 : 0);
+ bmov(source->btc_children + sidx + (shape == BSS_TRAPEZOID ? 0 : 1),
+ dest->btc_children + didx + (shape == BSS_TRAPEZOID ? 0 : 1),
+ c_count * sizeof (*source->btc_children));
+}
+
+static inline void
+bt_transfer_leaf(zfs_btree_t *tree, zfs_btree_leaf_t *source, uint64_t sidx,
+ uint64_t count, zfs_btree_leaf_t *dest, uint64_t didx)
+{
+ size_t size = tree->bt_elem_size;
+ ASSERT(!source->btl_hdr.bth_core);
+ ASSERT(!dest->btl_hdr.bth_core);
+
+ bmov(source->btl_elems + sidx * size, dest->btl_elems + didx * size,
+ count * size);
+}
+
+/*
+ * Find the first element in the subtree rooted at hdr, return its value and
+ * put its location in where if non-null.
+ */
+static void *
+zfs_btree_first_helper(zfs_btree_hdr_t *hdr, zfs_btree_index_t *where)
+{
+ zfs_btree_hdr_t *node;
+
+ for (node = hdr; node->bth_core; node =
+ ((zfs_btree_core_t *)node)->btc_children[0])
+ ;
+
+ ASSERT(!node->bth_core);
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)node;
+ if (where != NULL) {
+ where->bti_node = node;
+ where->bti_offset = 0;
+ where->bti_before = B_FALSE;
+ }
+ return (&leaf->btl_elems[0]);
+}
+
+/* Insert an element and a child into a core node at the given offset. */
+static void
+zfs_btree_insert_core_impl(zfs_btree_t *tree, zfs_btree_core_t *parent,
+ uint64_t offset, zfs_btree_hdr_t *new_node, void *buf)
+{
+ uint64_t size = tree->bt_elem_size;
+ zfs_btree_hdr_t *par_hdr = &parent->btc_hdr;
+ ASSERT3P(par_hdr, ==, new_node->bth_parent);
+ ASSERT3U(par_hdr->bth_count, <, BTREE_CORE_ELEMS);
+
+ if (zfs_btree_verify_intensity >= 5) {
+ zfs_btree_verify_poison_at(tree, par_hdr,
+ par_hdr->bth_count);
+ }
+ /* Shift existing elements and children */
+ uint64_t count = par_hdr->bth_count - offset;
+ bt_shift_core_right(tree, parent, offset, count,
+ BSS_PARALLELOGRAM);
+
+ /* Insert new values */
+ parent->btc_children[offset + 1] = new_node;
+ bmov(buf, parent->btc_elems + offset * size, size);
+ par_hdr->bth_count++;
+}
+
+/*
+ * Insert new_node into the parent of old_node directly after old_node, with
+ * buf as the dividing element between the two.
+ */
+static void
+zfs_btree_insert_into_parent(zfs_btree_t *tree, zfs_btree_hdr_t *old_node,
+ zfs_btree_hdr_t *new_node, void *buf)
+{
+ ASSERT3P(old_node->bth_parent, ==, new_node->bth_parent);
+ uint64_t size = tree->bt_elem_size;
+ zfs_btree_core_t *parent = old_node->bth_parent;
+ zfs_btree_hdr_t *par_hdr = &parent->btc_hdr;
+
+ /*
+ * If this is the root node we were splitting, we create a new root
+ * and increase the height of the tree.
+ */
+ if (parent == NULL) {
+ ASSERT3P(old_node, ==, tree->bt_root);
+ tree->bt_num_nodes++;
+ zfs_btree_core_t *new_root =
+ kmem_alloc(sizeof (zfs_btree_core_t) + BTREE_CORE_ELEMS *
+ size, KM_SLEEP);
+ zfs_btree_hdr_t *new_root_hdr = &new_root->btc_hdr;
+ new_root_hdr->bth_parent = NULL;
+ new_root_hdr->bth_core = B_TRUE;
+ new_root_hdr->bth_count = 1;
+
+ old_node->bth_parent = new_node->bth_parent = new_root;
+ new_root->btc_children[0] = old_node;
+ new_root->btc_children[1] = new_node;
+ bmov(buf, new_root->btc_elems, size);
+
+ tree->bt_height++;
+ tree->bt_root = new_root_hdr;
+ zfs_btree_poison_node(tree, new_root_hdr);
+ return;
+ }
+
+ /*
+ * Since we have the new separator, binary search for where to put
+ * new_node.
+ */
+ zfs_btree_index_t idx;
+ ASSERT(par_hdr->bth_core);
+ VERIFY3P(zfs_btree_find_in_buf(tree, parent->btc_elems,
+ par_hdr->bth_count, buf, &idx), ==, NULL);
+ ASSERT(idx.bti_before);
+ uint64_t offset = idx.bti_offset;
+ ASSERT3U(offset, <=, par_hdr->bth_count);
+ ASSERT3P(parent->btc_children[offset], ==, old_node);
+
+ /*
+ * If the parent isn't full, shift things to accommodate our insertions
+ * and return.
+ */
+ if (par_hdr->bth_count != BTREE_CORE_ELEMS) {
+ zfs_btree_insert_core_impl(tree, parent, offset, new_node, buf);
+ return;
+ }
+
+ /*
+ * We need to split this core node into two. Currently there are
+ * BTREE_CORE_ELEMS + 1 child nodes, and we are adding one for
+ * BTREE_CORE_ELEMS + 2. Some of the children will be part of the
+ * current node, and the others will be moved to the new core node.
+ * There are BTREE_CORE_ELEMS + 1 elements including the new one. One
+ * will be used as the new separator in our parent, and the others
+ * will be split among the two core nodes.
+ *
+ * Usually we will split the node in half evenly, with
+ * BTREE_CORE_ELEMS/2 elements in each node. If we're bulk loading, we
+ * instead move only about a quarter of the elements (and children) to
+ * the new node. Since the average state after a long time is a 3/4
+ * full node, shortcutting directly to that state improves efficiency.
+ *
+ * We do this in two stages: first we split into two nodes, and then we
+ * reuse our existing logic to insert the new element and child.
+ */
+ uint64_t move_count = MAX((BTREE_CORE_ELEMS / (tree->bt_bulk == NULL ?
+ 2 : 4)) - 1, 2);
+ uint64_t keep_count = BTREE_CORE_ELEMS - move_count - 1;
+ ASSERT3U(BTREE_CORE_ELEMS - move_count, >=, 2);
+ tree->bt_num_nodes++;
+ zfs_btree_core_t *new_parent = kmem_alloc(sizeof (zfs_btree_core_t) +
+ BTREE_CORE_ELEMS * size, KM_SLEEP);
+ zfs_btree_hdr_t *new_par_hdr = &new_parent->btc_hdr;
+ new_par_hdr->bth_parent = par_hdr->bth_parent;
+ new_par_hdr->bth_core = B_TRUE;
+ new_par_hdr->bth_count = move_count;
+ zfs_btree_poison_node(tree, new_par_hdr);
+
+ par_hdr->bth_count = keep_count;
+
+ bt_transfer_core(tree, parent, keep_count + 1, move_count, new_parent,
+ 0, BSS_TRAPEZOID);
+
+ /* Store the new separator in a buffer. */
+ uint8_t *tmp_buf = kmem_alloc(size, KM_SLEEP);
+ bmov(parent->btc_elems + keep_count * size, tmp_buf,
+ size);
+ zfs_btree_poison_node(tree, par_hdr);
+
+ if (offset < keep_count) {
+ /* Insert the new node into the left half */
+ zfs_btree_insert_core_impl(tree, parent, offset, new_node,
+ buf);
+
+ /*
+ * Move the new separator to the existing buffer.
+ */
+ bmov(tmp_buf, buf, size);
+ } else if (offset > keep_count) {
+ /* Insert the new node into the right half */
+ new_node->bth_parent = new_parent;
+ zfs_btree_insert_core_impl(tree, new_parent,
+ offset - keep_count - 1, new_node, buf);
+
+ /*
+ * Move the new separator to the existing buffer.
+ */
+ bmov(tmp_buf, buf, size);
+ } else {
+ /*
+ * Move the new separator into the right half, and replace it
+ * with buf. We also need to shift back the elements in the
+ * right half to accommodate new_node.
+ */
+ bt_shift_core_right(tree, new_parent, 0, move_count,
+ BSS_TRAPEZOID);
+ new_parent->btc_children[0] = new_node;
+ bmov(tmp_buf, new_parent->btc_elems, size);
+ new_par_hdr->bth_count++;
+ }
+ kmem_free(tmp_buf, size);
+ zfs_btree_poison_node(tree, par_hdr);
+
+ for (int i = 0; i <= new_parent->btc_hdr.bth_count; i++)
+ new_parent->btc_children[i]->bth_parent = new_parent;
+
+ for (int i = 0; i <= parent->btc_hdr.bth_count; i++)
+ ASSERT3P(parent->btc_children[i]->bth_parent, ==, parent);
+
+ /*
+ * Now that the node is split, we need to insert the new node into its
+ * parent. This may cause further splitting.
+ */
+ zfs_btree_insert_into_parent(tree, &parent->btc_hdr,
+ &new_parent->btc_hdr, buf);
+}
+
+/* Insert an element into a leaf node at the given offset. */
+static void
+zfs_btree_insert_leaf_impl(zfs_btree_t *tree, zfs_btree_leaf_t *leaf,
+ uint64_t idx, const void *value)
+{
+ uint64_t size = tree->bt_elem_size;
+ uint8_t *start = leaf->btl_elems + (idx * size);
+ zfs_btree_hdr_t *hdr = &leaf->btl_hdr;
+ uint64_t capacity __maybe_unused = P2ALIGN((BTREE_LEAF_SIZE -
+ sizeof (zfs_btree_hdr_t)) / size, 2);
+ uint64_t count = leaf->btl_hdr.bth_count - idx;
+ ASSERT3U(leaf->btl_hdr.bth_count, <, capacity);
+
+ if (zfs_btree_verify_intensity >= 5) {
+ zfs_btree_verify_poison_at(tree, &leaf->btl_hdr,
+ leaf->btl_hdr.bth_count);
+ }
+
+ bt_shift_leaf_right(tree, leaf, idx, count);
+ bmov(value, start, size);
+ hdr->bth_count++;
+}
+
+/* Helper function for inserting a new value into leaf at the given index. */
+static void
+zfs_btree_insert_into_leaf(zfs_btree_t *tree, zfs_btree_leaf_t *leaf,
+ const void *value, uint64_t idx)
+{
+ uint64_t size = tree->bt_elem_size;
+ uint64_t capacity = P2ALIGN((BTREE_LEAF_SIZE -
+ sizeof (zfs_btree_hdr_t)) / size, 2);
+
+ /*
+ * If the leaf isn't full, shift the elements after idx and insert
+ * value.
+ */
+ if (leaf->btl_hdr.bth_count != capacity) {
+ zfs_btree_insert_leaf_impl(tree, leaf, idx, value);
+ return;
+ }
+
+ /*
+ * Otherwise, we split the leaf node into two nodes. If we're not bulk
+ * inserting, each is of size (capacity / 2). If we are bulk
+ * inserting, we move a quarter of the elements to the new node so
+ * inserts into the old node don't cause immediate splitting but the
+ * tree stays relatively dense. Since the average state after a long
+ * time is a 3/4 full node, shortcutting directly to that state
+ * improves efficiency. At the end of the bulk insertion process
+ * we'll need to go through and fix up any nodes (the last leaf and
+ * its ancestors, potentially) that are below the minimum.
+ *
+ * In either case, we're left with one extra element. The leftover
+ * element will become the new dividing element between the two nodes.
+ */
+ uint64_t move_count = MAX(capacity / (tree->bt_bulk == NULL ? 2 : 4) -
+ 1, 2);
+ uint64_t keep_count = capacity - move_count - 1;
+ ASSERT3U(capacity - move_count, >=, 2);
+ tree->bt_num_nodes++;
+ zfs_btree_leaf_t *new_leaf = kmem_cache_alloc(zfs_btree_leaf_cache,
+ KM_SLEEP);
+ zfs_btree_hdr_t *new_hdr = &new_leaf->btl_hdr;
+ new_hdr->bth_parent = leaf->btl_hdr.bth_parent;
+ new_hdr->bth_core = B_FALSE;
+ new_hdr->bth_count = move_count;
+ zfs_btree_poison_node(tree, new_hdr);
+
+ leaf->btl_hdr.bth_count = keep_count;
+
+ if (tree->bt_bulk != NULL && leaf == tree->bt_bulk)
+ tree->bt_bulk = new_leaf;
+
+ /* Copy the back part to the new leaf. */
+ bt_transfer_leaf(tree, leaf, keep_count + 1, move_count, new_leaf,
+ 0);
+
+ /* We store the new separator in a buffer we control for simplicity. */
+ uint8_t *buf = kmem_alloc(size, KM_SLEEP);
+ bmov(leaf->btl_elems + (keep_count * size), buf, size);
+ zfs_btree_poison_node(tree, &leaf->btl_hdr);
+
+ if (idx < keep_count) {
+ /* Insert into the existing leaf. */
+ zfs_btree_insert_leaf_impl(tree, leaf, idx, value);
+ } else if (idx > keep_count) {
+ /* Insert into the new leaf. */
+ zfs_btree_insert_leaf_impl(tree, new_leaf, idx - keep_count -
+ 1, value);
+ } else {
+ /*
+ * Shift the elements in the new leaf to make room for the
+ * separator, and use the new value as the new separator.
+ */
+ bt_shift_leaf_right(tree, new_leaf, 0, move_count);
+ bmov(buf, new_leaf->btl_elems, size);
+ bmov(value, buf, size);
+ new_hdr->bth_count++;
+ }
+
+ /*
+ * Now that the node is split, we need to insert the new node into its
+ * parent. This may cause further splitting, bur only of core nodes.
+ */
+ zfs_btree_insert_into_parent(tree, &leaf->btl_hdr, &new_leaf->btl_hdr,
+ buf);
+ kmem_free(buf, size);
+}
+
+static uint64_t
+zfs_btree_find_parent_idx(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+ void *buf;
+ if (hdr->bth_core) {
+ buf = ((zfs_btree_core_t *)hdr)->btc_elems;
+ } else {
+ buf = ((zfs_btree_leaf_t *)hdr)->btl_elems;
+ }
+ zfs_btree_index_t idx;
+ zfs_btree_core_t *parent = hdr->bth_parent;
+ VERIFY3P(zfs_btree_find_in_buf(tree, parent->btc_elems,
+ parent->btc_hdr.bth_count, buf, &idx), ==, NULL);
+ ASSERT(idx.bti_before);
+ ASSERT3U(idx.bti_offset, <=, parent->btc_hdr.bth_count);
+ ASSERT3P(parent->btc_children[idx.bti_offset], ==, hdr);
+ return (idx.bti_offset);
+}
+
+/*
+ * Take the b-tree out of bulk insert mode. During bulk-insert mode, some
+ * nodes may violate the invariant that non-root nodes must be at least half
+ * full. All nodes violating this invariant should be the last node in their
+ * particular level. To correct the invariant, we take values from their left
+ * neighbor until they are half full. They must have a left neighbor at their
+ * level because the last node at a level is not the first node unless it's
+ * the root.
+ */
+static void
+zfs_btree_bulk_finish(zfs_btree_t *tree)
+{
+ ASSERT3P(tree->bt_bulk, !=, NULL);
+ ASSERT3P(tree->bt_root, !=, NULL);
+ zfs_btree_leaf_t *leaf = tree->bt_bulk;
+ zfs_btree_hdr_t *hdr = &leaf->btl_hdr;
+ zfs_btree_core_t *parent = hdr->bth_parent;
+ uint64_t size = tree->bt_elem_size;
+ uint64_t capacity = P2ALIGN((BTREE_LEAF_SIZE -
+ sizeof (zfs_btree_hdr_t)) / size, 2);
+
+ /*
+ * The invariant doesn't apply to the root node, if that's the only
+ * node in the tree we're done.
+ */
+ if (parent == NULL) {
+ tree->bt_bulk = NULL;
+ return;
+ }
+
+ /* First, take elements to rebalance the leaf node. */
+ if (hdr->bth_count < capacity / 2) {
+ /*
+ * First, find the left neighbor. The simplest way to do this
+ * is to call zfs_btree_prev twice; the first time finds some
+ * ancestor of this node, and the second time finds the left
+ * neighbor. The ancestor found is the lowest common ancestor
+ * of leaf and the neighbor.
+ */
+ zfs_btree_index_t idx = {
+ .bti_node = hdr,
+ .bti_offset = 0
+ };
+ VERIFY3P(zfs_btree_prev(tree, &idx, &idx), !=, NULL);
+ ASSERT(idx.bti_node->bth_core);
+ zfs_btree_core_t *common = (zfs_btree_core_t *)idx.bti_node;
+ uint64_t common_idx = idx.bti_offset;
+
+ VERIFY3P(zfs_btree_prev(tree, &idx, &idx), !=, NULL);
+ ASSERT(!idx.bti_node->bth_core);
+ zfs_btree_leaf_t *l_neighbor = (zfs_btree_leaf_t *)idx.bti_node;
+ zfs_btree_hdr_t *l_hdr = idx.bti_node;
+ uint64_t move_count = (capacity / 2) - hdr->bth_count;
+ ASSERT3U(l_neighbor->btl_hdr.bth_count - move_count, >=,
+ capacity / 2);
+
+ if (zfs_btree_verify_intensity >= 5) {
+ for (int i = 0; i < move_count; i++) {
+ zfs_btree_verify_poison_at(tree, hdr,
+ leaf->btl_hdr.bth_count + i);
+ }
+ }
+
+ /* First, shift elements in leaf back. */
+ bt_shift_leaf(tree, leaf, 0, hdr->bth_count, move_count,
+ BSD_RIGHT);
+
+ /* Next, move the separator from the common ancestor to leaf. */
+ uint8_t *separator = common->btc_elems + (common_idx * size);
+ uint8_t *out = leaf->btl_elems + ((move_count - 1) * size);
+ bmov(separator, out, size);
+ move_count--;
+
+ /*
+ * Now we move elements from the tail of the left neighbor to
+ * fill the remaining spots in leaf.
+ */
+ bt_transfer_leaf(tree, l_neighbor, l_hdr->bth_count -
+ move_count, move_count, leaf, 0);
+
+ /*
+ * Finally, move the new last element in the left neighbor to
+ * the separator.
+ */
+ bmov(l_neighbor->btl_elems + (l_hdr->bth_count -
+ move_count - 1) * size, separator, size);
+
+ /* Adjust the node's counts, and we're done. */
+ l_hdr->bth_count -= move_count + 1;
+ hdr->bth_count += move_count + 1;
+
+ ASSERT3U(l_hdr->bth_count, >=, capacity / 2);
+ ASSERT3U(hdr->bth_count, >=, capacity / 2);
+ zfs_btree_poison_node(tree, l_hdr);
+ }
+
+ /*
+ * Now we have to rebalance any ancestors of leaf that may also
+ * violate the invariant.
+ */
+ capacity = BTREE_CORE_ELEMS;
+ while (parent->btc_hdr.bth_parent != NULL) {
+ zfs_btree_core_t *cur = parent;
+ zfs_btree_hdr_t *hdr = &cur->btc_hdr;
+ parent = hdr->bth_parent;
+ /*
+ * If the invariant isn't violated, move on to the next
+ * ancestor.
+ */
+ if (hdr->bth_count >= capacity / 2)
+ continue;
+
+ /*
+ * Because the smallest number of nodes we can move when
+ * splitting is 2, we never need to worry about not having a
+ * left sibling (a sibling is a neighbor with the same parent).
+ */
+ uint64_t parent_idx = zfs_btree_find_parent_idx(tree, hdr);
+ ASSERT3U(parent_idx, >, 0);
+ zfs_btree_core_t *l_neighbor =
+ (zfs_btree_core_t *)parent->btc_children[parent_idx - 1];
+ uint64_t move_count = (capacity / 2) - hdr->bth_count;
+ ASSERT3U(l_neighbor->btc_hdr.bth_count - move_count, >=,
+ capacity / 2);
+
+ if (zfs_btree_verify_intensity >= 5) {
+ for (int i = 0; i < move_count; i++) {
+ zfs_btree_verify_poison_at(tree, hdr,
+ hdr->bth_count + i);
+ }
+ }
+ /* First, shift things in the right node back. */
+ bt_shift_core(tree, cur, 0, hdr->bth_count, move_count,
+ BSS_TRAPEZOID, BSD_RIGHT);
+
+ /* Next, move the separator to the right node. */
+ uint8_t *separator = parent->btc_elems + ((parent_idx - 1) *
+ size);
+ uint8_t *e_out = cur->btc_elems + ((move_count - 1) * size);
+ bmov(separator, e_out, size);
+
+ /*
+ * Now, move elements and children from the left node to the
+ * right. We move one more child than elements.
+ */
+ move_count--;
+ uint64_t move_idx = l_neighbor->btc_hdr.bth_count - move_count;
+ bt_transfer_core(tree, l_neighbor, move_idx, move_count, cur, 0,
+ BSS_TRAPEZOID);
+
+ /*
+ * Finally, move the last element in the left node to the
+ * separator's position.
+ */
+ move_idx--;
+ bmov(l_neighbor->btc_elems + move_idx * size, separator, size);
+
+ l_neighbor->btc_hdr.bth_count -= move_count + 1;
+ hdr->bth_count += move_count + 1;
+
+ ASSERT3U(l_neighbor->btc_hdr.bth_count, >=, capacity / 2);
+ ASSERT3U(hdr->bth_count, >=, capacity / 2);
+
+ zfs_btree_poison_node(tree, &l_neighbor->btc_hdr);
+
+ for (int i = 0; i <= hdr->bth_count; i++)
+ cur->btc_children[i]->bth_parent = cur;
+ }
+
+ tree->bt_bulk = NULL;
+}
+
+/*
+ * Insert value into tree at the location specified by where.
+ */
+void
+zfs_btree_add_idx(zfs_btree_t *tree, const void *value,
+ const zfs_btree_index_t *where)
+{
+ zfs_btree_index_t idx = {0};
+
+ /* If we're not inserting in the last leaf, end bulk insert mode. */
+ if (tree->bt_bulk != NULL) {
+ if (where->bti_node != &tree->bt_bulk->btl_hdr) {
+ zfs_btree_bulk_finish(tree);
+ VERIFY3P(zfs_btree_find(tree, value, &idx), ==, NULL);
+ where = &idx;
+ }
+ }
+
+ tree->bt_num_elems++;
+ /*
+ * If this is the first element in the tree, create a leaf root node
+ * and add the value to it.
+ */
+ if (where->bti_node == NULL) {
+ ASSERT3U(tree->bt_num_elems, ==, 1);
+ ASSERT3S(tree->bt_height, ==, -1);
+ ASSERT3P(tree->bt_root, ==, NULL);
+ ASSERT0(where->bti_offset);
+
+ tree->bt_num_nodes++;
+ zfs_btree_leaf_t *leaf = kmem_cache_alloc(zfs_btree_leaf_cache,
+ KM_SLEEP);
+ tree->bt_root = &leaf->btl_hdr;
+ tree->bt_height++;
+
+ zfs_btree_hdr_t *hdr = &leaf->btl_hdr;
+ hdr->bth_parent = NULL;
+ hdr->bth_core = B_FALSE;
+ hdr->bth_count = 0;
+ zfs_btree_poison_node(tree, hdr);
+
+ zfs_btree_insert_into_leaf(tree, leaf, value, 0);
+ tree->bt_bulk = leaf;
+ } else if (!where->bti_node->bth_core) {
+ /*
+ * If we're inserting into a leaf, go directly to the helper
+ * function.
+ */
+ zfs_btree_insert_into_leaf(tree,
+ (zfs_btree_leaf_t *)where->bti_node, value,
+ where->bti_offset);
+ } else {
+ /*
+ * If we're inserting into a core node, we can't just shift
+ * the existing element in that slot in the same node without
+ * breaking our ordering invariants. Instead we place the new
+ * value in the node at that spot and then insert the old
+ * separator into the first slot in the subtree to the right.
+ */
+ ASSERT(where->bti_node->bth_core);
+ zfs_btree_core_t *node = (zfs_btree_core_t *)where->bti_node;
+
+ /*
+ * We can ignore bti_before, because either way the value
+ * should end up in bti_offset.
+ */
+ uint64_t off = where->bti_offset;
+ zfs_btree_hdr_t *subtree = node->btc_children[off + 1];
+ size_t size = tree->bt_elem_size;
+ uint8_t *buf = kmem_alloc(size, KM_SLEEP);
+ bmov(node->btc_elems + off * size, buf, size);
+ bmov(value, node->btc_elems + off * size, size);
+
+ /*
+ * Find the first slot in the subtree to the right, insert
+ * there.
+ */
+ zfs_btree_index_t new_idx;
+ VERIFY3P(zfs_btree_first_helper(subtree, &new_idx), !=, NULL);
+ ASSERT0(new_idx.bti_offset);
+ ASSERT(!new_idx.bti_node->bth_core);
+ zfs_btree_insert_into_leaf(tree,
+ (zfs_btree_leaf_t *)new_idx.bti_node, buf, 0);
+ kmem_free(buf, size);
+ }
+ zfs_btree_verify(tree);
+}
+
+/*
+ * Return the first element in the tree, and put its location in where if
+ * non-null.
+ */
+void *
+zfs_btree_first(zfs_btree_t *tree, zfs_btree_index_t *where)
+{
+ if (tree->bt_height == -1) {
+ ASSERT0(tree->bt_num_elems);
+ return (NULL);
+ }
+ return (zfs_btree_first_helper(tree->bt_root, where));
+}
+
+/*
+ * Find the last element in the subtree rooted at hdr, return its value and
+ * put its location in where if non-null.
+ */
+static void *
+zfs_btree_last_helper(zfs_btree_t *btree, zfs_btree_hdr_t *hdr,
+ zfs_btree_index_t *where)
+{
+ zfs_btree_hdr_t *node;
+
+ for (node = hdr; node->bth_core; node =
+ ((zfs_btree_core_t *)node)->btc_children[node->bth_count])
+ ;
+
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)node;
+ if (where != NULL) {
+ where->bti_node = node;
+ where->bti_offset = node->bth_count - 1;
+ where->bti_before = B_FALSE;
+ }
+ return (leaf->btl_elems + (node->bth_count - 1) * btree->bt_elem_size);
+}
+
+/*
+ * Return the last element in the tree, and put its location in where if
+ * non-null.
+ */
+void *
+zfs_btree_last(zfs_btree_t *tree, zfs_btree_index_t *where)
+{
+ if (tree->bt_height == -1) {
+ ASSERT0(tree->bt_num_elems);
+ return (NULL);
+ }
+ return (zfs_btree_last_helper(tree, tree->bt_root, where));
+}
+
+/*
+ * This function contains the logic to find the next node in the tree. A
+ * helper function is used because there are multiple internal consumemrs of
+ * this logic. The done_func is used by zfs_btree_destroy_nodes to clean up each
+ * node after we've finished with it.
+ */
+static void *
+zfs_btree_next_helper(zfs_btree_t *tree, const zfs_btree_index_t *idx,
+ zfs_btree_index_t *out_idx,
+ void (*done_func)(zfs_btree_t *, zfs_btree_hdr_t *))
+{
+ if (idx->bti_node == NULL) {
+ ASSERT3S(tree->bt_height, ==, -1);
+ return (NULL);
+ }
+
+ uint64_t offset = idx->bti_offset;
+ if (!idx->bti_node->bth_core) {
+ /*
+ * When finding the next element of an element in a leaf,
+ * there are two cases. If the element isn't the last one in
+ * the leaf, in which case we just return the next element in
+ * the leaf. Otherwise, we need to traverse up our parents
+ * until we find one where our ancestor isn't the last child
+ * of its parent. Once we do, the next element is the
+ * separator after our ancestor in its parent.
+ */
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)idx->bti_node;
+ uint64_t new_off = offset + (idx->bti_before ? 0 : 1);
+ if (leaf->btl_hdr.bth_count > new_off) {
+ out_idx->bti_node = &leaf->btl_hdr;
+ out_idx->bti_offset = new_off;
+ out_idx->bti_before = B_FALSE;
+ return (leaf->btl_elems + new_off * tree->bt_elem_size);
+ }
+
+ zfs_btree_hdr_t *prev = &leaf->btl_hdr;
+ for (zfs_btree_core_t *node = leaf->btl_hdr.bth_parent;
+ node != NULL; node = node->btc_hdr.bth_parent) {
+ zfs_btree_hdr_t *hdr = &node->btc_hdr;
+ ASSERT(hdr->bth_core);
+ uint64_t i = zfs_btree_find_parent_idx(tree, prev);
+ if (done_func != NULL)
+ done_func(tree, prev);
+ if (i == hdr->bth_count) {
+ prev = hdr;
+ continue;
+ }
+ out_idx->bti_node = hdr;
+ out_idx->bti_offset = i;
+ out_idx->bti_before = B_FALSE;
+ return (node->btc_elems + i * tree->bt_elem_size);
+ }
+ if (done_func != NULL)
+ done_func(tree, prev);
+ /*
+ * We've traversed all the way up and been at the end of the
+ * node every time, so this was the last element in the tree.
+ */
+ return (NULL);
+ }
+
+ /* If we were before an element in a core node, return that element. */
+ ASSERT(idx->bti_node->bth_core);
+ zfs_btree_core_t *node = (zfs_btree_core_t *)idx->bti_node;
+ if (idx->bti_before) {
+ out_idx->bti_before = B_FALSE;
+ return (node->btc_elems + offset * tree->bt_elem_size);
+ }
+
+ /*
+ * The next element from one in a core node is the first element in
+ * the subtree just to the right of the separator.
+ */
+ zfs_btree_hdr_t *child = node->btc_children[offset + 1];
+ return (zfs_btree_first_helper(child, out_idx));
+}
+
+/*
+ * Return the next valued node in the tree. The same address can be safely
+ * passed for idx and out_idx.
+ */
+void *
+zfs_btree_next(zfs_btree_t *tree, const zfs_btree_index_t *idx,
+ zfs_btree_index_t *out_idx)
+{
+ return (zfs_btree_next_helper(tree, idx, out_idx, NULL));
+}
+
+/*
+ * Return the previous valued node in the tree. The same value can be safely
+ * passed for idx and out_idx.
+ */
+void *
+zfs_btree_prev(zfs_btree_t *tree, const zfs_btree_index_t *idx,
+ zfs_btree_index_t *out_idx)
+{
+ if (idx->bti_node == NULL) {
+ ASSERT3S(tree->bt_height, ==, -1);
+ return (NULL);
+ }
+
+ uint64_t offset = idx->bti_offset;
+ if (!idx->bti_node->bth_core) {
+ /*
+ * When finding the previous element of an element in a leaf,
+ * there are two cases. If the element isn't the first one in
+ * the leaf, in which case we just return the previous element
+ * in the leaf. Otherwise, we need to traverse up our parents
+ * until we find one where our previous ancestor isn't the
+ * first child. Once we do, the previous element is the
+ * separator after our previous ancestor.
+ */
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)idx->bti_node;
+ if (offset != 0) {
+ out_idx->bti_node = &leaf->btl_hdr;
+ out_idx->bti_offset = offset - 1;
+ out_idx->bti_before = B_FALSE;
+ return (leaf->btl_elems + (offset - 1) *
+ tree->bt_elem_size);
+ }
+ zfs_btree_hdr_t *prev = &leaf->btl_hdr;
+ for (zfs_btree_core_t *node = leaf->btl_hdr.bth_parent;
+ node != NULL; node = node->btc_hdr.bth_parent) {
+ zfs_btree_hdr_t *hdr = &node->btc_hdr;
+ ASSERT(hdr->bth_core);
+ uint64_t i = zfs_btree_find_parent_idx(tree, prev);
+ if (i == 0) {
+ prev = hdr;
+ continue;
+ }
+ out_idx->bti_node = hdr;
+ out_idx->bti_offset = i - 1;
+ out_idx->bti_before = B_FALSE;
+ return (node->btc_elems + (i - 1) * tree->bt_elem_size);
+ }
+ /*
+ * We've traversed all the way up and been at the start of the
+ * node every time, so this was the first node in the tree.
+ */
+ return (NULL);
+ }
+
+ /*
+ * The previous element from one in a core node is the last element in
+ * the subtree just to the left of the separator.
+ */
+ ASSERT(idx->bti_node->bth_core);
+ zfs_btree_core_t *node = (zfs_btree_core_t *)idx->bti_node;
+ zfs_btree_hdr_t *child = node->btc_children[offset];
+ return (zfs_btree_last_helper(tree, child, out_idx));
+}
+
+/*
+ * Get the value at the provided index in the tree.
+ *
+ * Note that the value returned from this function can be mutated, but only
+ * if it will not change the ordering of the element with respect to any other
+ * elements that could be in the tree.
+ */
+void *
+zfs_btree_get(zfs_btree_t *tree, zfs_btree_index_t *idx)
+{
+ ASSERT(!idx->bti_before);
+ if (!idx->bti_node->bth_core) {
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)idx->bti_node;
+ return (leaf->btl_elems + idx->bti_offset * tree->bt_elem_size);
+ }
+ ASSERT(idx->bti_node->bth_core);
+ zfs_btree_core_t *node = (zfs_btree_core_t *)idx->bti_node;
+ return (node->btc_elems + idx->bti_offset * tree->bt_elem_size);
+}
+
+/* Add the given value to the tree. Must not already be in the tree. */
+void
+zfs_btree_add(zfs_btree_t *tree, const void *node)
+{
+ zfs_btree_index_t where = {0};
+ VERIFY3P(zfs_btree_find(tree, node, &where), ==, NULL);
+ zfs_btree_add_idx(tree, node, &where);
+}
+
+/* Helper function to free a tree node. */
+static void
+zfs_btree_node_destroy(zfs_btree_t *tree, zfs_btree_hdr_t *node)
+{
+ tree->bt_num_nodes--;
+ if (!node->bth_core) {
+ kmem_cache_free(zfs_btree_leaf_cache, node);
+ } else {
+ kmem_free(node, sizeof (zfs_btree_core_t) +
+ BTREE_CORE_ELEMS * tree->bt_elem_size);
+ }
+}
+
+/*
+ * Remove the rm_hdr and the separator to its left from the parent node. The
+ * buffer that rm_hdr was stored in may already be freed, so its contents
+ * cannot be accessed.
+ */
+static void
+zfs_btree_remove_from_node(zfs_btree_t *tree, zfs_btree_core_t *node,
+ zfs_btree_hdr_t *rm_hdr)
+{
+ size_t size = tree->bt_elem_size;
+ uint64_t min_count = (BTREE_CORE_ELEMS / 2) - 1;
+ zfs_btree_hdr_t *hdr = &node->btc_hdr;
+ /*
+ * If the node is the root node and rm_hdr is one of two children,
+ * promote the other child to the root.
+ */
+ if (hdr->bth_parent == NULL && hdr->bth_count <= 1) {
+ ASSERT3U(hdr->bth_count, ==, 1);
+ ASSERT3P(tree->bt_root, ==, node);
+ ASSERT3P(node->btc_children[1], ==, rm_hdr);
+ tree->bt_root = node->btc_children[0];
+ node->btc_children[0]->bth_parent = NULL;
+ zfs_btree_node_destroy(tree, hdr);
+ tree->bt_height--;
+ return;
+ }
+
+ uint64_t idx;
+ for (idx = 0; idx <= hdr->bth_count; idx++) {
+ if (node->btc_children[idx] == rm_hdr)
+ break;
+ }
+ ASSERT3U(idx, <=, hdr->bth_count);
+
+ /*
+ * If the node is the root or it has more than the minimum number of
+ * children, just remove the child and separator, and return.
+ */
+ if (hdr->bth_parent == NULL ||
+ hdr->bth_count > min_count) {
+ /*
+ * Shift the element and children to the right of rm_hdr to
+ * the left by one spot.
+ */
+ bt_shift_core_left(tree, node, idx, hdr->bth_count - idx,
+ BSS_PARALLELOGRAM);
+ hdr->bth_count--;
+ zfs_btree_poison_node_at(tree, hdr, hdr->bth_count);
+ return;
+ }
+
+ ASSERT3U(hdr->bth_count, ==, min_count);
+
+ /*
+ * Now we try to take a node from a neighbor. We check left, then
+ * right. If the neighbor exists and has more than the minimum number
+ * of elements, we move the separator between us and them to our
+ * node, move their closest element (last for left, first for right)
+ * to the separator, and move their closest child to our node. Along
+ * the way we need to collapse the gap made by idx, and (for our right
+ * neighbor) the gap made by removing their first element and child.
+ *
+ * Note: this logic currently doesn't support taking from a neighbor
+ * that isn't a sibling (i.e. a neighbor with a different
+ * parent). This isn't critical functionality, but may be worth
+ * implementing in the future for completeness' sake.
+ */
+ zfs_btree_core_t *parent = hdr->bth_parent;
+ uint64_t parent_idx = zfs_btree_find_parent_idx(tree, hdr);
+
+ zfs_btree_hdr_t *l_hdr = (parent_idx == 0 ? NULL :
+ parent->btc_children[parent_idx - 1]);
+ if (l_hdr != NULL && l_hdr->bth_count > min_count) {
+ /* We can take a node from the left neighbor. */
+ ASSERT(l_hdr->bth_core);
+ zfs_btree_core_t *neighbor = (zfs_btree_core_t *)l_hdr;
+
+ /*
+ * Start by shifting the elements and children in the current
+ * node to the right by one spot.
+ */
+ bt_shift_core_right(tree, node, 0, idx - 1, BSS_TRAPEZOID);
+
+ /*
+ * Move the separator between node and neighbor to the first
+ * element slot in the current node.
+ */
+ uint8_t *separator = parent->btc_elems + (parent_idx - 1) *
+ size;
+ bmov(separator, node->btc_elems, size);
+
+ /* Move the last child of neighbor to our first child slot. */
+ zfs_btree_hdr_t **take_child = neighbor->btc_children +
+ l_hdr->bth_count;
+ bmov(take_child, node->btc_children, sizeof (*take_child));
+ node->btc_children[0]->bth_parent = node;
+
+ /* Move the last element of neighbor to the separator spot. */
+ uint8_t *take_elem = neighbor->btc_elems +
+ (l_hdr->bth_count - 1) * size;
+ bmov(take_elem, separator, size);
+ l_hdr->bth_count--;
+ zfs_btree_poison_node_at(tree, l_hdr, l_hdr->bth_count);
+ return;
+ }
+
+ zfs_btree_hdr_t *r_hdr = (parent_idx == parent->btc_hdr.bth_count ?
+ NULL : parent->btc_children[parent_idx + 1]);
+ if (r_hdr != NULL && r_hdr->bth_count > min_count) {
+ /* We can take a node from the right neighbor. */
+ ASSERT(r_hdr->bth_core);
+ zfs_btree_core_t *neighbor = (zfs_btree_core_t *)r_hdr;
+
+ /*
+ * Shift elements in node left by one spot to overwrite rm_hdr
+ * and the separator before it.
+ */
+ bt_shift_core_left(tree, node, idx, hdr->bth_count - idx,
+ BSS_PARALLELOGRAM);
+
+ /*
+ * Move the separator between node and neighbor to the last
+ * element spot in node.
+ */
+ uint8_t *separator = parent->btc_elems + parent_idx * size;
+ bmov(separator, node->btc_elems + (hdr->bth_count - 1) * size,
+ size);
+
+ /*
+ * Move the first child of neighbor to the last child spot in
+ * node.
+ */
+ zfs_btree_hdr_t **take_child = neighbor->btc_children;
+ bmov(take_child, node->btc_children + hdr->bth_count,
+ sizeof (*take_child));
+ node->btc_children[hdr->bth_count]->bth_parent = node;
+
+ /* Move the first element of neighbor to the separator spot. */
+ uint8_t *take_elem = neighbor->btc_elems;
+ bmov(take_elem, separator, size);
+ r_hdr->bth_count--;
+
+ /*
+ * Shift the elements and children of neighbor to cover the
+ * stolen elements.
+ */
+ bt_shift_core_left(tree, neighbor, 1, r_hdr->bth_count,
+ BSS_TRAPEZOID);
+ zfs_btree_poison_node_at(tree, r_hdr, r_hdr->bth_count);
+ return;
+ }
+
+ /*
+ * In this case, neither of our neighbors can spare an element, so we
+ * need to merge with one of them. We prefer the left one,
+ * arbitrarily. Move the separator into the leftmost merging node
+ * (which may be us or the left neighbor), and then move the right
+ * merging node's elements. Once that's done, we go back and delete
+ * the element we're removing. Finally, go into the parent and delete
+ * the right merging node and the separator. This may cause further
+ * merging.
+ */
+ zfs_btree_hdr_t *new_rm_hdr, *keep_hdr;
+ uint64_t new_idx = idx;
+ if (l_hdr != NULL) {
+ keep_hdr = l_hdr;
+ new_rm_hdr = hdr;
+ new_idx += keep_hdr->bth_count + 1;
+ } else {
+ ASSERT3P(r_hdr, !=, NULL);
+ keep_hdr = hdr;
+ new_rm_hdr = r_hdr;
+ parent_idx++;
+ }
+
+ ASSERT(keep_hdr->bth_core);
+ ASSERT(new_rm_hdr->bth_core);
+
+ zfs_btree_core_t *keep = (zfs_btree_core_t *)keep_hdr;
+ zfs_btree_core_t *rm = (zfs_btree_core_t *)new_rm_hdr;
+
+ if (zfs_btree_verify_intensity >= 5) {
+ for (int i = 0; i < new_rm_hdr->bth_count + 1; i++) {
+ zfs_btree_verify_poison_at(tree, keep_hdr,
+ keep_hdr->bth_count + i);
+ }
+ }
+
+ /* Move the separator into the left node. */
+ uint8_t *e_out = keep->btc_elems + keep_hdr->bth_count * size;
+ uint8_t *separator = parent->btc_elems + (parent_idx - 1) *
+ size;
+ bmov(separator, e_out, size);
+ keep_hdr->bth_count++;
+
+ /* Move all our elements and children into the left node. */
+ bt_transfer_core(tree, rm, 0, new_rm_hdr->bth_count, keep,
+ keep_hdr->bth_count, BSS_TRAPEZOID);
+
+ uint64_t old_count = keep_hdr->bth_count;
+
+ /* Update bookkeeping */
+ keep_hdr->bth_count += new_rm_hdr->bth_count;
+ ASSERT3U(keep_hdr->bth_count, ==, (min_count * 2) + 1);
+
+ /*
+ * Shift the element and children to the right of rm_hdr to
+ * the left by one spot.
+ */
+ ASSERT3P(keep->btc_children[new_idx], ==, rm_hdr);
+ bt_shift_core_left(tree, keep, new_idx, keep_hdr->bth_count - new_idx,
+ BSS_PARALLELOGRAM);
+ keep_hdr->bth_count--;
+
+ /* Reparent all our children to point to the left node. */
+ zfs_btree_hdr_t **new_start = keep->btc_children +
+ old_count - 1;
+ for (int i = 0; i < new_rm_hdr->bth_count + 1; i++)
+ new_start[i]->bth_parent = keep;
+ for (int i = 0; i <= keep_hdr->bth_count; i++) {
+ ASSERT3P(keep->btc_children[i]->bth_parent, ==, keep);
+ ASSERT3P(keep->btc_children[i], !=, rm_hdr);
+ }
+ zfs_btree_poison_node_at(tree, keep_hdr, keep_hdr->bth_count);
+
+ new_rm_hdr->bth_count = 0;
+ zfs_btree_node_destroy(tree, new_rm_hdr);
+ zfs_btree_remove_from_node(tree, parent, new_rm_hdr);
+}
+
+/* Remove the element at the specific location. */
+void
+zfs_btree_remove_idx(zfs_btree_t *tree, zfs_btree_index_t *where)
+{
+ size_t size = tree->bt_elem_size;
+ zfs_btree_hdr_t *hdr = where->bti_node;
+ uint64_t idx = where->bti_offset;
+ uint64_t capacity = P2ALIGN((BTREE_LEAF_SIZE -
+ sizeof (zfs_btree_hdr_t)) / size, 2);
+
+ ASSERT(!where->bti_before);
+ if (tree->bt_bulk != NULL) {
+ /*
+ * Leave bulk insert mode. Note that our index would be
+ * invalid after we correct the tree, so we copy the value
+ * we're planning to remove and find it again after
+ * bulk_finish.
+ */
+ uint8_t *value = zfs_btree_get(tree, where);
+ uint8_t *tmp = kmem_alloc(size, KM_SLEEP);
+ bmov(value, tmp, size);
+ zfs_btree_bulk_finish(tree);
+ VERIFY3P(zfs_btree_find(tree, tmp, where), !=, NULL);
+ kmem_free(tmp, size);
+ hdr = where->bti_node;
+ idx = where->bti_offset;
+ }
+
+ tree->bt_num_elems--;
+ /*
+ * If the element happens to be in a core node, we move a leaf node's
+ * element into its place and then remove the leaf node element. This
+ * makes the rebalance logic not need to be recursive both upwards and
+ * downwards.
+ */
+ if (hdr->bth_core) {
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ zfs_btree_hdr_t *left_subtree = node->btc_children[idx];
+ void *new_value = zfs_btree_last_helper(tree, left_subtree,
+ where);
+ ASSERT3P(new_value, !=, NULL);
+
+ bmov(new_value, node->btc_elems + idx * size, size);
+
+ hdr = where->bti_node;
+ idx = where->bti_offset;
+ ASSERT(!where->bti_before);
+ }
+
+ /*
+ * First, we'll update the leaf's metadata. Then, we shift any
+ * elements after the idx to the left. After that, we rebalance if
+ * needed.
+ */
+ ASSERT(!hdr->bth_core);
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)hdr;
+ ASSERT3U(hdr->bth_count, >, 0);
+
+ uint64_t min_count = (capacity / 2) - 1;
+
+ /*
+ * If we're over the minimum size or this is the root, just overwrite
+ * the value and return.
+ */
+ if (hdr->bth_count > min_count || hdr->bth_parent == NULL) {
+ hdr->bth_count--;
+ bt_shift_leaf_left(tree, leaf, idx + 1, hdr->bth_count - idx);
+ if (hdr->bth_parent == NULL) {
+ ASSERT0(tree->bt_height);
+ if (hdr->bth_count == 0) {
+ tree->bt_root = NULL;
+ tree->bt_height--;
+ zfs_btree_node_destroy(tree, &leaf->btl_hdr);
+ }
+ }
+ if (tree->bt_root != NULL)
+ zfs_btree_poison_node_at(tree, hdr, hdr->bth_count);
+ zfs_btree_verify(tree);
+ return;
+ }
+ ASSERT3U(hdr->bth_count, ==, min_count);
+
+ /*
+ * Now we try to take a node from a sibling. We check left, then
+ * right. If they exist and have more than the minimum number of
+ * elements, we move the separator between us and them to our node
+ * and move their closest element (last for left, first for right) to
+ * the separator. Along the way we need to collapse the gap made by
+ * idx, and (for our right neighbor) the gap made by removing their
+ * first element.
+ *
+ * Note: this logic currently doesn't support taking from a neighbor
+ * that isn't a sibling. This isn't critical functionality, but may be
+ * worth implementing in the future for completeness' sake.
+ */
+ zfs_btree_core_t *parent = hdr->bth_parent;
+ uint64_t parent_idx = zfs_btree_find_parent_idx(tree, hdr);
+
+ zfs_btree_hdr_t *l_hdr = (parent_idx == 0 ? NULL :
+ parent->btc_children[parent_idx - 1]);
+ if (l_hdr != NULL && l_hdr->bth_count > min_count) {
+ /* We can take a node from the left neighbor. */
+ ASSERT(!l_hdr->bth_core);
+
+ /*
+ * Move our elements back by one spot to make room for the
+ * stolen element and overwrite the element being removed.
+ */
+ bt_shift_leaf_right(tree, leaf, 0, idx);
+ uint8_t *separator = parent->btc_elems + (parent_idx - 1) *
+ size;
+ uint8_t *take_elem = ((zfs_btree_leaf_t *)l_hdr)->btl_elems +
+ (l_hdr->bth_count - 1) * size;
+ /* Move the separator to our first spot. */
+ bmov(separator, leaf->btl_elems, size);
+
+ /* Move our neighbor's last element to the separator. */
+ bmov(take_elem, separator, size);
+
+ /* Update the bookkeeping. */
+ l_hdr->bth_count--;
+ zfs_btree_poison_node_at(tree, l_hdr, l_hdr->bth_count);
+
+ zfs_btree_verify(tree);
+ return;
+ }
+
+ zfs_btree_hdr_t *r_hdr = (parent_idx == parent->btc_hdr.bth_count ?
+ NULL : parent->btc_children[parent_idx + 1]);
+ if (r_hdr != NULL && r_hdr->bth_count > min_count) {
+ /* We can take a node from the right neighbor. */
+ ASSERT(!r_hdr->bth_core);
+ zfs_btree_leaf_t *neighbor = (zfs_btree_leaf_t *)r_hdr;
+
+ /*
+ * Move our elements after the element being removed forwards
+ * by one spot to make room for the stolen element and
+ * overwrite the element being removed.
+ */
+ bt_shift_leaf_left(tree, leaf, idx + 1, hdr->bth_count - idx -
+ 1);
+
+ uint8_t *separator = parent->btc_elems + parent_idx * size;
+ uint8_t *take_elem = ((zfs_btree_leaf_t *)r_hdr)->btl_elems;
+ /* Move the separator between us to our last spot. */
+ bmov(separator, leaf->btl_elems + (hdr->bth_count - 1) * size,
+ size);
+
+ /* Move our neighbor's first element to the separator. */
+ bmov(take_elem, separator, size);
+
+ /* Update the bookkeeping. */
+ r_hdr->bth_count--;
+
+ /*
+ * Move our neighbors elements forwards to overwrite the
+ * stolen element.
+ */
+ bt_shift_leaf_left(tree, neighbor, 1, r_hdr->bth_count);
+ zfs_btree_poison_node_at(tree, r_hdr, r_hdr->bth_count);
+ zfs_btree_verify(tree);
+ return;
+ }
+
+ /*
+ * In this case, neither of our neighbors can spare an element, so we
+ * need to merge with one of them. We prefer the left one,
+ * arbitrarily. Move the separator into the leftmost merging node
+ * (which may be us or the left neighbor), and then move the right
+ * merging node's elements. Once that's done, we go back and delete
+ * the element we're removing. Finally, go into the parent and delete
+ * the right merging node and the separator. This may cause further
+ * merging.
+ */
+ zfs_btree_hdr_t *rm_hdr, *keep_hdr;
+ uint64_t new_idx = idx;
+ if (l_hdr != NULL) {
+ keep_hdr = l_hdr;
+ rm_hdr = hdr;
+ new_idx += keep_hdr->bth_count + 1; // 449
+ } else {
+ ASSERT3P(r_hdr, !=, NULL);
+ keep_hdr = hdr;
+ rm_hdr = r_hdr;
+ parent_idx++;
+ }
+
+ ASSERT(!keep_hdr->bth_core);
+ ASSERT(!rm_hdr->bth_core);
+ ASSERT3U(keep_hdr->bth_count, ==, min_count);
+ ASSERT3U(rm_hdr->bth_count, ==, min_count);
+
+ zfs_btree_leaf_t *keep = (zfs_btree_leaf_t *)keep_hdr;
+ zfs_btree_leaf_t *rm = (zfs_btree_leaf_t *)rm_hdr;
+
+ if (zfs_btree_verify_intensity >= 5) {
+ for (int i = 0; i < rm_hdr->bth_count + 1; i++) {
+ zfs_btree_verify_poison_at(tree, keep_hdr,
+ keep_hdr->bth_count + i);
+ }
+ }
+ /*
+ * Move the separator into the first open spot in the left
+ * neighbor.
+ */
+ uint8_t *out = keep->btl_elems + keep_hdr->bth_count * size;
+ uint8_t *separator = parent->btc_elems + (parent_idx - 1) *
+ size;
+ bmov(separator, out, size);
+ keep_hdr->bth_count++;
+
+ /* Move our elements to the left neighbor. */
+ bt_transfer_leaf(tree, rm, 0, rm_hdr->bth_count, keep,
+ keep_hdr->bth_count);
+
+ /* Update the bookkeeping. */
+ keep_hdr->bth_count += rm_hdr->bth_count;
+ ASSERT3U(keep_hdr->bth_count, ==, min_count * 2 + 1);
+
+ /* Remove the value from the node */
+ keep_hdr->bth_count--;
+ bt_shift_leaf_left(tree, keep, new_idx + 1, keep_hdr->bth_count -
+ new_idx);
+ zfs_btree_poison_node_at(tree, keep_hdr, keep_hdr->bth_count);
+
+ rm_hdr->bth_count = 0;
+ zfs_btree_node_destroy(tree, rm_hdr);
+ /* Remove the emptied node from the parent. */
+ zfs_btree_remove_from_node(tree, parent, rm_hdr);
+ zfs_btree_verify(tree);
+}
+
+/* Remove the given value from the tree. */
+void
+zfs_btree_remove(zfs_btree_t *tree, const void *value)
+{
+ zfs_btree_index_t where = {0};
+ VERIFY3P(zfs_btree_find(tree, value, &where), !=, NULL);
+ zfs_btree_remove_idx(tree, &where);
+}
+
+/* Return the number of elements in the tree. */
+ulong_t
+zfs_btree_numnodes(zfs_btree_t *tree)
+{
+ return (tree->bt_num_elems);
+}
+
+/*
+ * This function is used to visit all the elements in the tree before
+ * destroying the tree. This allows the calling code to perform any cleanup it
+ * needs to do. This is more efficient than just removing the first element
+ * over and over, because it removes all rebalancing. Once the destroy_nodes()
+ * function has been called, no other btree operations are valid until it
+ * returns NULL, which point the only valid operation is zfs_btree_destroy().
+ *
+ * example:
+ *
+ * zfs_btree_index_t *cookie = NULL;
+ * my_data_t *node;
+ *
+ * while ((node = zfs_btree_destroy_nodes(tree, &cookie)) != NULL)
+ * free(node->ptr);
+ * zfs_btree_destroy(tree);
+ *
+ */
+void *
+zfs_btree_destroy_nodes(zfs_btree_t *tree, zfs_btree_index_t **cookie)
+{
+ if (*cookie == NULL) {
+ if (tree->bt_height == -1)
+ return (NULL);
+ *cookie = kmem_alloc(sizeof (**cookie), KM_SLEEP);
+ return (zfs_btree_first(tree, *cookie));
+ }
+
+ void *rval = zfs_btree_next_helper(tree, *cookie, *cookie,
+ zfs_btree_node_destroy);
+ if (rval == NULL) {
+ tree->bt_root = NULL;
+ tree->bt_height = -1;
+ tree->bt_num_elems = 0;
+ kmem_free(*cookie, sizeof (**cookie));
+ tree->bt_bulk = NULL;
+ }
+ return (rval);
+}
+
+static void
+zfs_btree_clear_helper(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+ if (hdr->bth_core) {
+ zfs_btree_core_t *btc = (zfs_btree_core_t *)hdr;
+ for (int i = 0; i <= hdr->bth_count; i++) {
+ zfs_btree_clear_helper(tree, btc->btc_children[i]);
+ }
+ }
+
+ zfs_btree_node_destroy(tree, hdr);
+}
+
+void
+zfs_btree_clear(zfs_btree_t *tree)
+{
+ if (tree->bt_root == NULL) {
+ ASSERT0(tree->bt_num_elems);
+ return;
+ }
+
+ zfs_btree_clear_helper(tree, tree->bt_root);
+ tree->bt_num_elems = 0;
+ tree->bt_root = NULL;
+ tree->bt_num_nodes = 0;
+ tree->bt_height = -1;
+ tree->bt_bulk = NULL;
+}
+
+void
+zfs_btree_destroy(zfs_btree_t *tree)
+{
+ ASSERT0(tree->bt_num_elems);
+ ASSERT3P(tree->bt_root, ==, NULL);
+}
+
+/* Verify that every child of this node has the correct parent pointer. */
+static void
+zfs_btree_verify_pointers_helper(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+ if (!hdr->bth_core)
+ return;
+
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ for (int i = 0; i <= hdr->bth_count; i++) {
+ VERIFY3P(node->btc_children[i]->bth_parent, ==, hdr);
+ zfs_btree_verify_pointers_helper(tree, node->btc_children[i]);
+ }
+}
+
+/* Verify that every node has the correct parent pointer. */
+static void
+zfs_btree_verify_pointers(zfs_btree_t *tree)
+{
+ if (tree->bt_height == -1) {
+ VERIFY3P(tree->bt_root, ==, NULL);
+ return;
+ }
+ VERIFY3P(tree->bt_root->bth_parent, ==, NULL);
+ zfs_btree_verify_pointers_helper(tree, tree->bt_root);
+}
+
+/*
+ * Verify that all the current node and its children satisfy the count
+ * invariants, and return the total count in the subtree rooted in this node.
+ */
+static uint64_t
+zfs_btree_verify_counts_helper(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+ if (!hdr->bth_core) {
+ if (tree->bt_root != hdr && hdr != &tree->bt_bulk->btl_hdr) {
+ uint64_t capacity = P2ALIGN((BTREE_LEAF_SIZE -
+ sizeof (zfs_btree_hdr_t)) / tree->bt_elem_size, 2);
+ VERIFY3U(hdr->bth_count, >=, (capacity / 2) - 1);
+ }
+
+ return (hdr->bth_count);
+ } else {
+
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ uint64_t ret = hdr->bth_count;
+ if (tree->bt_root != hdr && tree->bt_bulk == NULL)
+ VERIFY3P(hdr->bth_count, >=, BTREE_CORE_ELEMS / 2 - 1);
+ for (int i = 0; i <= hdr->bth_count; i++) {
+ ret += zfs_btree_verify_counts_helper(tree,
+ node->btc_children[i]);
+ }
+
+ return (ret);
+ }
+}
+
+/*
+ * Verify that all nodes satisfy the invariants and that the total number of
+ * elements is correct.
+ */
+static void
+zfs_btree_verify_counts(zfs_btree_t *tree)
+{
+ EQUIV(tree->bt_num_elems == 0, tree->bt_height == -1);
+ if (tree->bt_height == -1) {
+ return;
+ }
+ VERIFY3P(zfs_btree_verify_counts_helper(tree, tree->bt_root), ==,
+ tree->bt_num_elems);
+}
+
+/*
+ * Check that the subtree rooted at this node has a uniform height. Returns
+ * the number of nodes under this node, to help verify bt_num_nodes.
+ */
+static uint64_t
+zfs_btree_verify_height_helper(zfs_btree_t *tree, zfs_btree_hdr_t *hdr,
+ int64_t height)
+{
+ if (!hdr->bth_core) {
+ VERIFY0(height);
+ return (1);
+ }
+
+ VERIFY(hdr->bth_core);
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ uint64_t ret = 1;
+ for (int i = 0; i <= hdr->bth_count; i++) {
+ ret += zfs_btree_verify_height_helper(tree,
+ node->btc_children[i], height - 1);
+ }
+ return (ret);
+}
+
+/*
+ * Check that the tree rooted at this node has a uniform height, and that the
+ * bt_height in the tree is correct.
+ */
+static void
+zfs_btree_verify_height(zfs_btree_t *tree)
+{
+ EQUIV(tree->bt_height == -1, tree->bt_root == NULL);
+ if (tree->bt_height == -1) {
+ return;
+ }
+
+ VERIFY3U(zfs_btree_verify_height_helper(tree, tree->bt_root,
+ tree->bt_height), ==, tree->bt_num_nodes);
+}
+
+/*
+ * Check that the elements in this node are sorted, and that if this is a core
+ * node, the separators are properly between the subtrees they separaate and
+ * that the children also satisfy this requirement.
+ */
+static void
+zfs_btree_verify_order_helper(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+ size_t size = tree->bt_elem_size;
+ if (!hdr->bth_core) {
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)hdr;
+ for (int i = 1; i < hdr->bth_count; i++) {
+ VERIFY3S(tree->bt_compar(leaf->btl_elems + (i - 1) *
+ size, leaf->btl_elems + i * size), ==, -1);
+ }
+ return;
+ }
+
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ for (int i = 1; i < hdr->bth_count; i++) {
+ VERIFY3S(tree->bt_compar(node->btc_elems + (i - 1) * size,
+ node->btc_elems + i * size), ==, -1);
+ }
+ for (int i = 0; i < hdr->bth_count; i++) {
+ uint8_t *left_child_last = NULL;
+ zfs_btree_hdr_t *left_child_hdr = node->btc_children[i];
+ if (left_child_hdr->bth_core) {
+ zfs_btree_core_t *left_child =
+ (zfs_btree_core_t *)left_child_hdr;
+ left_child_last = left_child->btc_elems +
+ (left_child_hdr->bth_count - 1) * size;
+ } else {
+ zfs_btree_leaf_t *left_child =
+ (zfs_btree_leaf_t *)left_child_hdr;
+ left_child_last = left_child->btl_elems +
+ (left_child_hdr->bth_count - 1) * size;
+ }
+ if (tree->bt_compar(node->btc_elems + i * size,
+ left_child_last) != 1) {
+ panic("btree: compar returned %d (expected 1) at "
+ "%px %d: compar(%px, %px)", tree->bt_compar(
+ node->btc_elems + i * size, left_child_last),
+ (void *)node, i, (void *)(node->btc_elems + i *
+ size), (void *)left_child_last);
+ }
+
+ uint8_t *right_child_first = NULL;
+ zfs_btree_hdr_t *right_child_hdr = node->btc_children[i + 1];
+ if (right_child_hdr->bth_core) {
+ zfs_btree_core_t *right_child =
+ (zfs_btree_core_t *)right_child_hdr;
+ right_child_first = right_child->btc_elems;
+ } else {
+ zfs_btree_leaf_t *right_child =
+ (zfs_btree_leaf_t *)right_child_hdr;
+ right_child_first = right_child->btl_elems;
+ }
+ if (tree->bt_compar(node->btc_elems + i * size,
+ right_child_first) != -1) {
+ panic("btree: compar returned %d (expected -1) at "
+ "%px %d: compar(%px, %px)", tree->bt_compar(
+ node->btc_elems + i * size, right_child_first),
+ (void *)node, i, (void *)(node->btc_elems + i *
+ size), (void *)right_child_first);
+ }
+ }
+ for (int i = 0; i <= hdr->bth_count; i++) {
+ zfs_btree_verify_order_helper(tree, node->btc_children[i]);
+ }
+}
+
+/* Check that all elements in the tree are in sorted order. */
+static void
+zfs_btree_verify_order(zfs_btree_t *tree)
+{
+ EQUIV(tree->bt_height == -1, tree->bt_root == NULL);
+ if (tree->bt_height == -1) {
+ return;
+ }
+
+ zfs_btree_verify_order_helper(tree, tree->bt_root);
+}
+
+#ifdef ZFS_DEBUG
+/* Check that all unused memory is poisoned correctly. */
+static void
+zfs_btree_verify_poison_helper(zfs_btree_t *tree, zfs_btree_hdr_t *hdr)
+{
+ size_t size = tree->bt_elem_size;
+ if (!hdr->bth_core) {
+ zfs_btree_leaf_t *leaf = (zfs_btree_leaf_t *)hdr;
+ uint8_t val = 0x0f;
+ for (int i = hdr->bth_count * size; i < BTREE_LEAF_SIZE -
+ sizeof (zfs_btree_hdr_t); i++) {
+ VERIFY3U(leaf->btl_elems[i], ==, val);
+ }
+ } else {
+ zfs_btree_core_t *node = (zfs_btree_core_t *)hdr;
+ uint8_t val = 0x0f;
+ for (int i = hdr->bth_count * size; i < BTREE_CORE_ELEMS * size;
+ i++) {
+ VERIFY3U(node->btc_elems[i], ==, val);
+ }
+
+ for (int i = hdr->bth_count + 1; i <= BTREE_CORE_ELEMS; i++) {
+ VERIFY3P(node->btc_children[i], ==,
+ (zfs_btree_hdr_t *)BTREE_POISON);
+ }
+
+ for (int i = 0; i <= hdr->bth_count; i++) {
+ zfs_btree_verify_poison_helper(tree,
+ node->btc_children[i]);
+ }
+ }
+}
+#endif
+
+/* Check that unused memory in the tree is still poisoned. */
+static void
+zfs_btree_verify_poison(zfs_btree_t *tree)
+{
+#ifdef ZFS_DEBUG
+ if (tree->bt_height == -1)
+ return;
+ zfs_btree_verify_poison_helper(tree, tree->bt_root);
+#endif
+}
+
+void
+zfs_btree_verify(zfs_btree_t *tree)
+{
+ if (zfs_btree_verify_intensity == 0)
+ return;
+ zfs_btree_verify_height(tree);
+ if (zfs_btree_verify_intensity == 1)
+ return;
+ zfs_btree_verify_pointers(tree);
+ if (zfs_btree_verify_intensity == 2)
+ return;
+ zfs_btree_verify_counts(tree);
+ if (zfs_btree_verify_intensity == 3)
+ return;
+ zfs_btree_verify_order(tree);
+
+ if (zfs_btree_verify_intensity == 4)
+ return;
+ zfs_btree_verify_poison(tree);
+}
diff --git a/sys/contrib/openzfs/module/zfs/dataset_kstats.c b/sys/contrib/openzfs/module/zfs/dataset_kstats.c
new file mode 100644
index 000000000000..e46a0926d557
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/dataset_kstats.c
@@ -0,0 +1,215 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2018 Datto Inc.
+ */
+
+#include <sys/dataset_kstats.h>
+#include <sys/dmu_objset.h>
+#include <sys/dsl_dataset.h>
+#include <sys/spa.h>
+
+static dataset_kstat_values_t empty_dataset_kstats = {
+ { "dataset_name", KSTAT_DATA_STRING },
+ { "writes", KSTAT_DATA_UINT64 },
+ { "nwritten", KSTAT_DATA_UINT64 },
+ { "reads", KSTAT_DATA_UINT64 },
+ { "nread", KSTAT_DATA_UINT64 },
+ { "nunlinks", KSTAT_DATA_UINT64 },
+ { "nunlinked", KSTAT_DATA_UINT64 },
+};
+
+static int
+dataset_kstats_update(kstat_t *ksp, int rw)
+{
+ dataset_kstats_t *dk = ksp->ks_private;
+ ASSERT3P(dk->dk_kstats->ks_data, ==, ksp->ks_data);
+
+ if (rw == KSTAT_WRITE)
+ return (EACCES);
+
+ dataset_kstat_values_t *dkv = dk->dk_kstats->ks_data;
+ dkv->dkv_writes.value.ui64 =
+ aggsum_value(&dk->dk_aggsums.das_writes);
+ dkv->dkv_nwritten.value.ui64 =
+ aggsum_value(&dk->dk_aggsums.das_nwritten);
+ dkv->dkv_reads.value.ui64 =
+ aggsum_value(&dk->dk_aggsums.das_reads);
+ dkv->dkv_nread.value.ui64 =
+ aggsum_value(&dk->dk_aggsums.das_nread);
+ dkv->dkv_nunlinks.value.ui64 =
+ aggsum_value(&dk->dk_aggsums.das_nunlinks);
+ dkv->dkv_nunlinked.value.ui64 =
+ aggsum_value(&dk->dk_aggsums.das_nunlinked);
+
+ return (0);
+}
+
+void
+dataset_kstats_create(dataset_kstats_t *dk, objset_t *objset)
+{
+ /*
+ * There should not be anything wrong with having kstats for
+ * snapshots. Since we are not sure how useful they would be
+ * though nor how much their memory overhead would matter in
+ * a filesystem with many snapshots, we skip them for now.
+ */
+ if (dmu_objset_is_snapshot(objset))
+ return;
+
+ /*
+ * At the time of this writing, KSTAT_STRLEN is 255 in Linux,
+ * and the spa_name can theoretically be up to 256 characters.
+ * In reality though the spa_name can be 240 characters max
+ * [see origin directory name check in pool_namecheck()]. Thus,
+ * the naming scheme for the module name below should not cause
+ * any truncations. In the event that a truncation does happen
+ * though, due to some future change, we silently skip creating
+ * the kstat and log the event.
+ */
+ char kstat_module_name[KSTAT_STRLEN];
+ int n = snprintf(kstat_module_name, sizeof (kstat_module_name),
+ "zfs/%s", spa_name(dmu_objset_spa(objset)));
+ if (n < 0) {
+ zfs_dbgmsg("failed to create dataset kstat for objset %lld: "
+ " snprintf() for kstat module name returned %d",
+ (unsigned long long)dmu_objset_id(objset), n);
+ return;
+ } else if (n >= KSTAT_STRLEN) {
+ zfs_dbgmsg("failed to create dataset kstat for objset %lld: "
+ "kstat module name length (%d) exceeds limit (%d)",
+ (unsigned long long)dmu_objset_id(objset),
+ n, KSTAT_STRLEN);
+ return;
+ }
+
+ char kstat_name[KSTAT_STRLEN];
+ n = snprintf(kstat_name, sizeof (kstat_name), "objset-0x%llx",
+ (unsigned long long)dmu_objset_id(objset));
+ if (n < 0) {
+ zfs_dbgmsg("failed to create dataset kstat for objset %lld: "
+ " snprintf() for kstat name returned %d",
+ (unsigned long long)dmu_objset_id(objset), n);
+ return;
+ }
+ ASSERT3U(n, <, KSTAT_STRLEN);
+
+ kstat_t *kstat = kstat_create(kstat_module_name, 0, kstat_name,
+ "dataset", KSTAT_TYPE_NAMED,
+ sizeof (empty_dataset_kstats) / sizeof (kstat_named_t),
+ KSTAT_FLAG_VIRTUAL);
+ if (kstat == NULL)
+ return;
+
+ dataset_kstat_values_t *dk_kstats =
+ kmem_alloc(sizeof (empty_dataset_kstats), KM_SLEEP);
+ bcopy(&empty_dataset_kstats, dk_kstats,
+ sizeof (empty_dataset_kstats));
+
+ char *ds_name = kmem_zalloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP);
+ dsl_dataset_name(objset->os_dsl_dataset, ds_name);
+ KSTAT_NAMED_STR_PTR(&dk_kstats->dkv_ds_name) = ds_name;
+ KSTAT_NAMED_STR_BUFLEN(&dk_kstats->dkv_ds_name) =
+ ZFS_MAX_DATASET_NAME_LEN;
+
+ kstat->ks_data = dk_kstats;
+ kstat->ks_update = dataset_kstats_update;
+ kstat->ks_private = dk;
+ kstat->ks_data_size += ZFS_MAX_DATASET_NAME_LEN;
+
+ kstat_install(kstat);
+ dk->dk_kstats = kstat;
+
+ aggsum_init(&dk->dk_aggsums.das_writes, 0);
+ aggsum_init(&dk->dk_aggsums.das_nwritten, 0);
+ aggsum_init(&dk->dk_aggsums.das_reads, 0);
+ aggsum_init(&dk->dk_aggsums.das_nread, 0);
+ aggsum_init(&dk->dk_aggsums.das_nunlinks, 0);
+ aggsum_init(&dk->dk_aggsums.das_nunlinked, 0);
+}
+
+void
+dataset_kstats_destroy(dataset_kstats_t *dk)
+{
+ if (dk->dk_kstats == NULL)
+ return;
+
+ dataset_kstat_values_t *dkv = dk->dk_kstats->ks_data;
+ kmem_free(KSTAT_NAMED_STR_PTR(&dkv->dkv_ds_name),
+ KSTAT_NAMED_STR_BUFLEN(&dkv->dkv_ds_name));
+ kmem_free(dkv, sizeof (empty_dataset_kstats));
+
+ kstat_delete(dk->dk_kstats);
+ dk->dk_kstats = NULL;
+
+ aggsum_fini(&dk->dk_aggsums.das_writes);
+ aggsum_fini(&dk->dk_aggsums.das_nwritten);
+ aggsum_fini(&dk->dk_aggsums.das_reads);
+ aggsum_fini(&dk->dk_aggsums.das_nread);
+ aggsum_fini(&dk->dk_aggsums.das_nunlinks);
+ aggsum_fini(&dk->dk_aggsums.das_nunlinked);
+}
+
+void
+dataset_kstats_update_write_kstats(dataset_kstats_t *dk,
+ int64_t nwritten)
+{
+ ASSERT3S(nwritten, >=, 0);
+
+ if (dk->dk_kstats == NULL)
+ return;
+
+ aggsum_add(&dk->dk_aggsums.das_writes, 1);
+ aggsum_add(&dk->dk_aggsums.das_nwritten, nwritten);
+}
+
+void
+dataset_kstats_update_read_kstats(dataset_kstats_t *dk,
+ int64_t nread)
+{
+ ASSERT3S(nread, >=, 0);
+
+ if (dk->dk_kstats == NULL)
+ return;
+
+ aggsum_add(&dk->dk_aggsums.das_reads, 1);
+ aggsum_add(&dk->dk_aggsums.das_nread, nread);
+}
+
+void
+dataset_kstats_update_nunlinks_kstat(dataset_kstats_t *dk, int64_t delta)
+{
+ if (dk->dk_kstats == NULL)
+ return;
+
+ aggsum_add(&dk->dk_aggsums.das_nunlinks, delta);
+}
+
+void
+dataset_kstats_update_nunlinked_kstat(dataset_kstats_t *dk, int64_t delta)
+{
+ if (dk->dk_kstats == NULL)
+ return;
+
+ aggsum_add(&dk->dk_aggsums.das_nunlinked, delta);
+}
diff --git a/sys/contrib/openzfs/module/zfs/dbuf.c b/sys/contrib/openzfs/module/zfs/dbuf.c
new file mode 100644
index 000000000000..2de1f4e4c267
--- /dev/null
+++ b/sys/contrib/openzfs/module/zfs/dbuf.c
@@ -0,0 +1,4741 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2012, 2019 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
+ * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
+ * Copyright (c) 2019, Klara Inc.
+ * Copyright (c) 2019, Allan Jude
+ */
+
+#include <sys/zfs_context.h>
+#include <sys/arc.h>
+#include <sys/dmu.h>
+#include <sys/dmu_send.h>
+#include <sys/dmu_impl.h>
+#include <sys/dbuf.h>
+#include <sys/dmu_objset.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dmu_tx.h>
+#include <sys/spa.h>
+#include <sys/zio.h>
+#include <sys/dmu_zfetch.h>
+#include <sys/sa.h>
+#include <sys/sa_impl.h>
+#include <sys/zfeature.h>
+#include <sys/blkptr.h>
+#include <sys/range_tree.h>
+#include <sys/trace_zfs.h>
+#include <sys/callb.h>
+#include <sys/abd.h>
+#include <sys/vdev.h>
+#include <cityhash.h>
+#include <sys/spa_impl.h>
+
+kstat_t *dbuf_ksp;
+
+typedef struct dbuf_stats {
+ /*
+ * Various statistics about the size of the dbuf cache.
+ */
+ kstat_named_t cache_count;
+ kstat_named_t cache_size_bytes;
+ kstat_named_t cache_size_bytes_max;
+ /*
+ * Statistics regarding the bounds on the dbuf cache size.
+ */
+ kstat_named_t cache_target_bytes;
+ kstat_named_t cache_lowater_bytes;
+ kstat_named_t cache_hiwater_bytes;
+ /*
+ * Total number of dbuf cache evictions that have occurred.
+ */
+ kstat_named_t cache_total_evicts;
+ /*
+ * The distribution of dbuf levels in the dbuf cache and
+ * the total size of all dbufs at each level.
+ */
+ kstat_named_t cache_levels[DN_MAX_LEVELS];
+ kstat_named_t cache_levels_bytes[DN_MAX_LEVELS];
+ /*
+ * Statistics about the dbuf hash table.
+ */
+ kstat_named_t hash_hits;
+ kstat_named_t hash_misses;
+ kstat_named_t hash_collisions;
+ kstat_named_t hash_elements;
+ kstat_named_t hash_elements_max;
+ /*
+ * Number of sublists containing more than one dbuf in the dbuf
+ * hash table. Keep track of the longest hash chain.
+ */
+ kstat_named_t hash_chains;
+ kstat_named_t hash_chain_max;
+ /*
+ * Number of times a dbuf_create() discovers that a dbuf was
+ * already created and in the dbuf hash table.
+ */
+ kstat_named_t hash_insert_race;
+ /*
+ * Statistics about the size of the metadata dbuf cache.
+ */
+ kstat_named_t metadata_cache_count;
+ kstat_named_t metadata_cache_size_bytes;
+ kstat_named_t metadata_cache_size_bytes_max;
+ /*
+ * For diagnostic purposes, this is incremented whenever we can't add
+ * something to the metadata cache because it's full, and instead put
+ * the data in the regular dbuf cache.
+ */
+ kstat_named_t metadata_cache_overflow;
+} dbuf_stats_t;
+
+dbuf_stats_t dbuf_stats = {
+ { "cache_count", KSTAT_DATA_UINT64 },
+ { "cache_size_bytes", KSTAT_DATA_UINT64 },
+ { "cache_size_bytes_max", KSTAT_DATA_UINT64 },
+ { "cache_target_bytes", KSTAT_DATA_UINT64 },
+ { "cache_lowater_bytes", KSTAT_DATA_UINT64 },
+ { "cache_hiwater_bytes", KSTAT_DATA_UINT64 },
+ { "cache_total_evicts", KSTAT_DATA_UINT64 },
+ { { "cache_levels_N", KSTAT_DATA_UINT64 } },
+ { { "cache_levels_bytes_N", KSTAT_DATA_UINT64 } },
+ { "hash_hits", KSTAT_DATA_UINT64 },
+ { "hash_misses", KSTAT_DATA_UINT64 },
+ { "hash_collisions", KSTAT_DATA_UINT64 },
+ { "hash_elements", KSTAT_DATA_UINT64 },
+ { "hash_elements_max", KSTAT_DATA_UINT64 },
+ { "hash_chains", KSTAT_DATA_UINT64 },
+ { "hash_chain_max", KSTAT_DATA_UINT64 },
+ { "hash_insert_race", KSTAT_DATA_UINT64 },
+ { "metadata_cache_count", KSTAT_DATA_UINT64 },
+ { "metadata_cache_size_bytes", KSTAT_DATA_UINT64 },
+ { "metadata_cache_size_bytes_max", KSTAT_DATA_UINT64 },
+ { "metadata_cache_overflow", KSTAT_DATA_UINT64 }
+};
+
+#define DBUF_STAT_INCR(stat, val) \
+ atomic_add_64(&dbuf_stats.stat.value.ui64, (val));
+#define DBUF_STAT_DECR(stat, val) \
+ DBUF_STAT_INCR(stat, -(val));
+#define DBUF_STAT_BUMP(stat) \
+ DBUF_STAT_INCR(stat, 1);
+#define DBUF_STAT_BUMPDOWN(stat) \
+ DBUF_STAT_INCR(stat, -1);
+#define DBUF_STAT_MAX(stat, v) { \
+ uint64_t _m; \
+ while ((v) > (_m = dbuf_stats.stat.value.ui64) && \
+ (_m != atomic_cas_64(&dbuf_stats.stat.value.ui64, _m, (v))))\
+ continue; \
+}
+
+static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
+static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
+static void dbuf_sync_leaf_verify_bonus_dnode(dbuf_dirty_record_t *dr);
+static int dbuf_read_verify_dnode_crypt(dmu_buf_impl_t *db, uint32_t flags);
+
+extern inline void dmu_buf_init_user(dmu_buf_user_t *dbu,
+ dmu_buf_evict_func_t *evict_func_sync,
+ dmu_buf_evict_func_t *evict_func_async,
+ dmu_buf_t **clear_on_evict_dbufp);
+
+/*
+ * Global data structures and functions for the dbuf cache.
+ */
+static kmem_cache_t *dbuf_kmem_cache;
+static taskq_t *dbu_evict_taskq;
+
+static kthread_t *dbuf_cache_evict_thread;
+static kmutex_t dbuf_evict_lock;
+static kcondvar_t dbuf_evict_cv;
+static boolean_t dbuf_evict_thread_exit;
+
+/*
+ * There are two dbuf caches; each dbuf can only be in one of them at a time.
+ *
+ * 1. Cache of metadata dbufs, to help make read-heavy administrative commands
+ * from /sbin/zfs run faster. The "metadata cache" specifically stores dbufs
+ * that represent the metadata that describes filesystems/snapshots/
+ * bookmarks/properties/etc. We only evict from this cache when we export a
+ * pool, to short-circuit as much I/O as possible for all administrative
+ * commands that need the metadata. There is no eviction policy for this
+ * cache, because we try to only include types in it which would occupy a
+ * very small amount of space per object but create a large impact on the
+ * performance of these commands. Instead, after it reaches a maximum size
+ * (which should only happen on very small memory systems with a very large
+ * number of filesystem objects), we stop taking new dbufs into the
+ * metadata cache, instead putting them in the normal dbuf cache.
+ *
+ * 2. LRU cache of dbufs. The dbuf cache maintains a list of dbufs that
+ * are not currently held but have been recently released. These dbufs
+ * are not eligible for arc eviction until they are aged out of the cache.
+ * Dbufs that are aged out of the cache will be immediately destroyed and
+ * become eligible for arc eviction.
+ *
+ * Dbufs are added to these caches once the last hold is released. If a dbuf is
+ * later accessed and still exists in the dbuf cache, then it will be removed
+ * from the cache and later re-added to the head of the cache.
+ *
+ * If a given dbuf meets the requirements for the metadata cache, it will go
+ * there, otherwise it will be considered for the generic LRU dbuf cache. The
+ * caches and the refcounts tracking their sizes are stored in an array indexed
+ * by those caches' matching enum values (from dbuf_cached_state_t).
+ */
+typedef struct dbuf_cache {
+ multilist_t *cache;
+ zfs_refcount_t size;
+} dbuf_cache_t;
+dbuf_cache_t dbuf_caches[DB_CACHE_MAX];
+
+/* Size limits for the caches */
+unsigned long dbuf_cache_max_bytes = ULONG_MAX;
+unsigned long dbuf_metadata_cache_max_bytes = ULONG_MAX;
+
+/* Set the default sizes of the caches to log2 fraction of arc size */
+int dbuf_cache_shift = 5;
+int dbuf_metadata_cache_shift = 6;
+
+static unsigned long dbuf_cache_target_bytes(void);
+static unsigned long dbuf_metadata_cache_target_bytes(void);
+
+/*
+ * The LRU dbuf cache uses a three-stage eviction policy:
+ * - A low water marker designates when the dbuf eviction thread
+ * should stop evicting from the dbuf cache.
+ * - When we reach the maximum size (aka mid water mark), we
+ * signal the eviction thread to run.
+ * - The high water mark indicates when the eviction thread
+ * is unable to keep up with the incoming load and eviction must
+ * happen in the context of the calling thread.
+ *
+ * The dbuf cache:
+ * (max size)
+ * low water mid water hi water
+ * +----------------------------------------+----------+----------+
+ * | | | |
+ * | | | |
+ * | | | |
+ * | | | |
+ * +----------------------------------------+----------+----------+
+ * stop signal evict
+ * evicting eviction directly
+ * thread
+ *
+ * The high and low water marks indicate the operating range for the eviction
+ * thread. The low water mark is, by default, 90% of the total size of the
+ * cache and the high water mark is at 110% (both of these percentages can be
+ * changed by setting dbuf_cache_lowater_pct and dbuf_cache_hiwater_pct,
+ * respectively). The eviction thread will try to ensure that the cache remains
+ * within this range by waking up every second and checking if the cache is
+ * above the low water mark. The thread can also be woken up by callers adding
+ * elements into the cache if the cache is larger than the mid water (i.e max
+ * cache size). Once the eviction thread is woken up and eviction is required,
+ * it will continue evicting buffers until it's able to reduce the cache size
+ * to the low water mark. If the cache size continues to grow and hits the high
+ * water mark, then callers adding elements to the cache will begin to evict
+ * directly from the cache until the cache is no longer above the high water
+ * mark.
+ */
+
+/*
+ * The percentage above and below the maximum cache size.
+ */
+uint_t dbuf_cache_hiwater_pct = 10;
+uint_t dbuf_cache_lowater_pct = 10;
+
+/* ARGSUSED */
+static int
+dbuf_cons(void *vdb, void *unused, int kmflag)
+{
+ dmu_buf_impl_t *db = vdb;
+ bzero(db, sizeof (dmu_buf_impl_t));
+
+ mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
+ rw_init(&db->db_rwlock, NULL, RW_DEFAULT, NULL);
+ cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
+ multilist_link_init(&db->db_cache_link);
+ zfs_refcount_create(&db->db_holds);
+
+ return (0);
+}
+
+/* ARGSUSED */
+static void
+dbuf_dest(void *vdb, void *unused)
+{
+ dmu_buf_impl_t *db = vdb;
+ mutex_destroy(&db->db_mtx);
+ rw_destroy(&db->db_rwlock);
+ cv_destroy(&db->db_changed);
+ ASSERT(!multilist_link_active(&db->db_cache_link));
+ zfs_refcount_destroy(&db->db_holds);
+}
+
+/*
+ * dbuf hash table routines
+ */
+static dbuf_hash_table_t dbuf_hash_table;
+
+static uint64_t dbuf_hash_count;
+
+/*
+ * We use Cityhash for this. It's fast, and has good hash properties without
+ * requiring any large static buffers.
+ */
+static uint64_t
+dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
+{
+ return (cityhash4((uintptr_t)os, obj, (uint64_t)lvl, blkid));
+}
+
+#define DTRACE_SET_STATE(db, why) \
+ DTRACE_PROBE2(dbuf__state_change, dmu_buf_impl_t *, db, \
+ const char *, why)
+
+#define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
+ ((dbuf)->db.db_object == (obj) && \
+ (dbuf)->db_objset == (os) && \
+ (dbuf)->db_level == (level) && \
+ (dbuf)->db_blkid == (blkid))
+
+dmu_buf_impl_t *
+dbuf_find(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid)
+{
+ dbuf_hash_table_t *h = &dbuf_hash_table;
+ uint64_t hv;
+ uint64_t idx;
+ dmu_buf_impl_t *db;
+
+ hv = dbuf_hash(os, obj, level, blkid);
+ idx = hv & h->hash_table_mask;
+
+ mutex_enter(DBUF_HASH_MUTEX(h, idx));
+ for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
+ if (DBUF_EQUAL(db, os, obj, level, blkid)) {
+ mutex_enter(&db->db_mtx);
+ if (db->db_state != DB_EVICTING) {
+ mutex_exit(DBUF_HASH_MUTEX(h, idx));
+ return (db);
+ }
+ mutex_exit(&db->db_mtx);
+ }
+ }
+ mutex_exit(DBUF_HASH_MUTEX(h, idx));
+ return (NULL);
+}
+
+static dmu_buf_impl_t *
+dbuf_find_bonus(objset_t *os, uint64_t object)
+{
+ dnode_t *dn;
+ dmu_buf_impl_t *db = NULL;
+
+ if (dnode_hold(os, object, FTAG, &dn) == 0) {
+ rw_enter(&dn->dn_struct_rwlock, RW_READER);
+ if (dn->dn_bonus != NULL) {
+ db = dn->dn_bonus;
+ mutex_enter(&db->db_mtx);
+ }
+ rw_exit(&dn->dn_struct_rwlock);
+ dnode_rele(dn, FTAG);
+ }
+ return (db);
+}
+
+/*
+ * Insert an entry into the hash table. If there is already an element
+ * equal to elem in the hash table, then the already existing element
+ * will be returned and the new element will not be inserted.
+ * Otherwise returns NULL.
+ */
+static dmu_buf_impl_t *
+dbuf_hash_insert(dmu_buf_impl_t *db)
+{
+ dbuf_hash_table_t *h = &dbuf_hash_table;
+ objset_t *os = db->db_objset;
+ uint64_t obj = db->db.db_object;
+ int level = db->db_level;
+ uint64_t blkid, hv, idx;
+ dmu_buf_impl_t *dbf;
+ uint32_t i;
+
+ blkid = db->db_blkid;
+ hv = dbuf_hash(os, obj, level, blkid);
+ idx = hv & h->hash_table_mask;
+
+ mutex_enter(DBUF_HASH_MUTEX(h, idx));
+ for (dbf = h->hash_table[idx], i = 0; dbf != NULL;
+ dbf = dbf->db_hash_next, i++) {
+ if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
+ mutex_enter(&dbf->db_mtx);
+ if (dbf->db_state != DB_EVICTING) {
+ mutex_exit(DBUF_HASH_MUTEX(h, idx));
+ return (dbf);
+ }
+ mutex_exit(&dbf->db_mtx);
+ }
+ }
+
+ if (i > 0) {
+ DBUF_STAT_BUMP(hash_collisions);
+ if (i == 1)
+ DBUF_STAT_BUMP(hash_chains);
+
+ DBUF_STAT_MAX(hash_chain_max, i);
+ }
+
+ mutex_enter(&db->db_mtx);
+ db->db_hash_next = h->hash_table[idx];
+ h->hash_table[idx] = db;
+ mutex_exit(DBUF_HASH_MUTEX(h, idx));
+ atomic_inc_64(&dbuf_hash_count);
+ DBUF_STAT_MAX(hash_elements_max, dbuf_hash_count);
+
+ return (NULL);
+}
+
+/*
+ * This returns whether this dbuf should be stored in the metadata cache, which
+ * is based on whether it's from one of the dnode types that store data related
+ * to traversing dataset hierarchies.
+ */
+static boolean_t
+dbuf_include_in_metadata_cache(dmu_buf_impl_t *db)
+{
+ DB_DNODE_ENTER(db);
+ dmu_object_type_t type = DB_DNODE(db)->dn_type;
+ DB_DNODE_EXIT(db);
+
+ /* Check if this dbuf is one of the types we care about */
+ if (DMU_OT_IS_METADATA_CACHED(type)) {
+ /* If we hit this, then we set something up wrong in dmu_ot */
+ ASSERT(DMU_OT_IS_METADATA(type));
+
+ /*
+ * Sanity check for small-memory systems: don't allocate too
+ * much memory for this purpose.
+ */
+ if (zfs_refcount_count(
+ &dbuf_caches[DB_DBUF_METADATA_CACHE].size) >
+ dbuf_metadata_cache_target_bytes()) {
+ DBUF_STAT_BUMP(metadata_cache_overflow);
+ return (B_FALSE);
+ }
+
+ return (B_TRUE);
+ }
+
+ return (B_FALSE);
+}
+
+/*
+ * Remove an entry from the hash table. It must be in the EVICTING state.
+ */
+static void
+dbuf_hash_remove(dmu_buf_impl_t *db)
+{
+ dbuf_hash_table_t *h = &dbuf_hash_table;
+ uint64_t hv, idx;
+ dmu_buf_impl_t *dbf, **dbp;
+
+ hv = dbuf_hash(db->db_objset, db->db.db_object,
+ db->db_level, db->db_blkid);
+ idx = hv & h->hash_table_mask;
+
+ /*
+ * We mustn't hold db_mtx to maintain lock ordering:
+ * DBUF_HASH_MUTEX > db_mtx.
+ */
+ ASSERT(zfs_refcount_is_zero(&db->db_holds));
+ ASSERT(db->db_state == DB_EVICTING);
+ ASSERT(!MUTEX_HELD(&db->db_mtx));
+
+ mutex_enter(DBUF_HASH_MUTEX(h, idx));
+ dbp = &h->hash_table[idx];
+ while ((dbf = *dbp) != db) {
+ dbp = &dbf->db_hash_next;
+ ASSERT(dbf != NULL);
+ }
+ *dbp = db->db_hash_next;
+ db->db_hash_next = NULL;
+ if (h->hash_table[idx] &&
+ h->hash_table[idx]->db_hash_next == NULL)
+ DBUF_STAT_BUMPDOWN(hash_chains);
+ mutex_exit(DBUF_HASH_MUTEX(h, idx));
+ atomic_dec_64(&dbuf_hash_count);
+}
+
+typedef enum {
+ DBVU_EVICTING,
+ DBVU_NOT_EVICTING
+} dbvu_verify_type_t;
+
+static void
+dbuf_verify_user(dmu_buf_impl_t *db, dbvu_verify_type_t verify_type)
+{
+#ifdef ZFS_DEBUG
+ int64_t holds;
+
+ if (db->db_user == NULL)
+ return;
+
+ /* Only data blocks support the attachment of user data. */
+ ASSERT(db->db_level == 0);
+
+ /* Clients must resolve a dbuf before attaching user data. */
+ ASSERT(db->db.db_data != NULL);
+ ASSERT3U(db->db_state, ==, DB_CACHED);
+
+ holds = zfs_refcount_count(&db->db_holds);
+ if (verify_type == DBVU_EVICTING) {
+ /*
+ * Immediate eviction occurs when holds == dirtycnt.
+ * For normal eviction buffers, holds is zero on
+ * eviction, except when dbuf_fix_old_data() calls
+ * dbuf_clear_data(). However, the hold count can grow
+ * during eviction even though db_mtx is held (see
+ * dmu_bonus_hold() for an example), so we can only
+ * test the generic invariant that holds >= dirtycnt.
+ */
+ ASSERT3U(holds, >=, db->db_dirtycnt);
+ } else {
+ if (db->db_user_immediate_evict == TRUE)
+ ASSERT3U(holds, >=, db->db_dirtycnt);
+ else
+ ASSERT3U(holds, >, 0);
+ }
+#endif
+}
+
+static void
+dbuf_evict_user(dmu_buf_impl_t *db)
+{
+ dmu_buf_user_t *dbu = db->db_user;
+
+ ASSERT(MUTEX_HELD(&db->db_mtx));
+
+ if (dbu == NULL)
+ return;
+
+ dbuf_verify_user(db, DBVU_EVICTING);
+ db->db_user = NULL;
+
+#ifdef ZFS_DEBUG
+ if (dbu->dbu_clear_on_evict_dbufp != NULL)
+ *dbu->dbu_clear_on_evict_dbufp = NULL;
+#endif
+
+ /*
+ * There are two eviction callbacks - one that we call synchronously
+ * and one that we invoke via a taskq. The async one is useful for
+ * avoiding lock order reversals and limiting stack depth.
+ *
+ * Note that if we have a sync callback but no async callback,
+ * it's likely that the sync callback will free the structure
+ * containing the dbu. In that case we need to take care to not
+ * dereference dbu after calling the sync evict func.
+ */
+ boolean_t has_async = (dbu->dbu_evict_func_async != NULL);
+
+ if (dbu->dbu_evict_func_sync != NULL)
+ dbu->dbu_evict_func_sync(dbu);
+
+ if (has_async) {
+ taskq_dispatch_ent(dbu_evict_taskq, dbu->dbu_evict_func_async,
+ dbu, 0, &dbu->dbu_tqent);
+ }
+}
+
+boolean_t
+dbuf_is_metadata(dmu_buf_impl_t *db)
+{
+ /*
+ * Consider indirect blocks and spill blocks to be meta data.
+ */
+ if (db->db_level > 0 || db->db_blkid == DMU_SPILL_BLKID) {
+ return (B_TRUE);
+ } else {
+ boolean_t is_metadata;
+
+ DB_DNODE_ENTER(db);
+ is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
+ DB_DNODE_EXIT(db);
+
+ return (is_metadata);
+ }
+}
+
+
+/*
+ * This function *must* return indices evenly distributed between all
+ * sublists of the multilist. This is needed due to how the dbuf eviction
+ * code is laid out; dbuf_evict_thread() assumes dbufs are evenly
+ * distributed between all sublists and uses this assumption when
+ * deciding which sublist to evict from and how much to evict from it.
+ */
+static unsigned int
+dbuf_cache_multilist_index_func(multilist_t *ml, void *obj)
+{
+ dmu_buf_impl_t *db = obj;
+
+ /*
+ * The assumption here, is the hash value for a given
+ * dmu_buf_impl_t will remain constant throughout it's lifetime
+ * (i.e. it's objset, object, level and blkid fields don't change).
+ * Thus, we don't need to store the dbuf's sublist index
+ * on insertion, as this index can be recalculated on removal.
+ *
+ * Also, the low order bits of the hash value are thought to be
+ * distributed evenly. Otherwise, in the case that the multilist
+ * has a power of two number of sublists, each sublists' usage
+ * would not be evenly distributed.
+ */
+ return (dbuf_hash(db->db_objset, db->db.db_object,
+ db->db_level, db->db_blkid) %
+ multilist_get_num_sublists(ml));
+}
+
+/*
+ * The target size of the dbuf cache can grow with the ARC target,
+ * unless limited by the tunable dbuf_cache_max_bytes.
+ */
+static inline unsigned long
+dbuf_cache_target_bytes(void)
+{
+ return (MIN(dbuf_cache_max_bytes,
+ arc_target_bytes() >> dbuf_cache_shift));
+}
+
+/*
+ * The target size of the dbuf metadata cache can grow with the ARC target,
+ * unless limited by the tunable dbuf_metadata_cache_max_bytes.
+ */
+static inline unsigned long
+dbuf_metadata_cache_target_bytes(void)
+{
+ return (MIN(dbuf_metadata_cache_max_bytes,
+ arc_target_bytes() >> dbuf_metadata_cache_shift));
+}
+
+static inline uint64_t
+dbuf_cache_hiwater_bytes(void)
+{
+ uint64_t dbuf_cache_target = dbuf_cache_target_bytes();
+ return (dbuf_cache_target +
+ (dbuf_cache_target * dbuf_cache_hiwater_pct) / 100);
+}
+
+static inline uint64_t
+dbuf_cache_lowater_bytes(void)
+{
+ uint64_t dbuf_cache_target = dbuf_cache_target_bytes();
+ return (dbuf_cache_target -
+ (dbuf_cache_target * dbuf_cache_lowater_pct) / 100);
+}
+
+static inline boolean_t
+dbuf_cache_above_lowater(void)
+{
+ return (zfs_refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) >
+ dbuf_cache_lowater_bytes());
+}
+
+/*
+ * Evict the oldest eligible dbuf from the dbuf cache.
+ */
+static void
+dbuf_evict_one(void)
+{
+ int idx = multilist_get_random_index(dbuf_caches[DB_DBUF_CACHE].cache);
+ multilist_sublist_t *mls = multilist_sublist_lock(
+ dbuf_caches[DB_DBUF_CACHE].cache, idx);
+
+ ASSERT(!MUTEX_HELD(&dbuf_evict_lock));
+
+ dmu_buf_impl_t *db = multilist_sublist_tail(mls);
+ while (db != NULL && mutex_tryenter(&db->db_mtx) == 0) {
+ db = multilist_sublist_prev(mls, db);
+ }
+
+ DTRACE_PROBE2(dbuf__evict__one, dmu_buf_impl_t *, db,
+ multilist_sublist_t *, mls);
+
+ if (db != NULL) {
+ multilist_sublist_remove(mls, db);
+ multilist_sublist_unlock(mls);
+ (void) zfs_refcount_remove_many(
+ &dbuf_caches[DB_DBUF_CACHE].size, db->db.db_size, db);
+ DBUF_STAT_BUMPDOWN(cache_levels[db->db_level]);
+ DBUF_STAT_BUMPDOWN(cache_count);
+ DBUF_STAT_DECR(cache_levels_bytes[db->db_level],
+ db->db.db_size);
+ ASSERT3U(db->db_caching_status, ==, DB_DBUF_CACHE);
+ db->db_caching_status = DB_NO_CACHE;
+ dbuf_destroy(db);
+ DBUF_STAT_BUMP(cache_total_evicts);
+ } else {
+ multilist_sublist_unlock(mls);
+ }
+}
+
+/*
+ * The dbuf evict thread is responsible for aging out dbufs from the
+ * cache. Once the cache has reached it's maximum size, dbufs are removed
+ * and destroyed. The eviction thread will continue running until the size
+ * of the dbuf cache is at or below the maximum size. Once the dbuf is aged
+ * out of the cache it is destroyed and becomes eligible for arc eviction.
+ */
+/* ARGSUSED */
+static void
+dbuf_evict_thread(void *unused)
+{
+ callb_cpr_t cpr;
+
+ CALLB_CPR_INIT(&cpr, &dbuf_evict_lock, callb_generic_cpr, FTAG);
+
+ mutex_enter(&dbuf_evict_lock);
+ while (!dbuf_evict_thread_exit) {
+ while (!dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
+ CALLB_CPR_SAFE_BEGIN(&cpr);
+ (void) cv_timedwait_sig_hires(&dbuf_evict_cv,
+ &dbuf_evict_lock, SEC2NSEC(1), MSEC2NSEC(1), 0);
+ CALLB_CPR_SAFE_END(&cpr, &dbuf_evict_lock);
+ }
+ mutex_exit(&dbuf_evict_lock);
+
+ /*
+ * Keep evicting as long as we're above the low water mark
+ * for the cache. We do this without holding the locks to
+ * minimize lock contention.
+ */
+ while (dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
+ dbuf_evict_one();
+ }
+
+ mutex_enter(&dbuf_evict_lock);
+ }
+
+ dbuf_evict_thread_exit = B_FALSE;
+ cv_broadcast(&dbuf_evict_cv);
+ CALLB_CPR_EXIT(&cpr); /* drops dbuf_evict_lock */
+ thread_exit();
+}
+
+/*
+ * Wake up the dbuf eviction thread if the dbuf cache is at its max size.
+ * If the dbuf cache is at its high water mark, then evict a dbuf from the
+ * dbuf cache using the callers context.
+ */
+static void
+dbuf_evict_notify(uint64_t size)
+{
+ /*
+ * We check if we should evict without holding the dbuf_evict_lock,
+ * because it's OK to occasionally make the wrong decision here,
+ * and grabbing the lock results in massive lock contention.
+ */
+ if (size > dbuf_cache_target_bytes()) {
+ if (size > dbuf_cache_hiwater_bytes())
+ dbuf_evict_one();
+ cv_signal(&dbuf_evict_cv);
+ }
+}
+
+static int
+dbuf_kstat_update(kstat_t *ksp, int rw)
+{
+ dbuf_stats_t *ds = ksp->ks_data;
+
+ if (rw == KSTAT_WRITE) {
+ return (SET_ERROR(EACCES));
+ } else {
+ ds->metadata_cache_size_bytes.value.ui64 = zfs_refcount_count(
+ &dbuf_caches[DB_DBUF_METADATA_CACHE].size);
+ ds->cache_size_bytes.value.ui64 =
+ zfs_refcount_count(&dbuf_caches[DB_DBUF_CACHE].size);
+ ds->cache_target_bytes.value.ui64 = dbuf_cache_target_bytes();
+ ds->cache_hiwater_bytes.value.ui64 = dbuf_cache_hiwater_bytes();
+ ds->cache_lowater_bytes.value.ui64 = dbuf_cache_lowater_bytes();
+ ds->hash_elements.value.ui64 = dbuf_hash_count;
+ }
+
+ return (0);
+}
+
+void
+dbuf_init(void)
+{
+ uint64_t hsize = 1ULL << 16;
+ dbuf_hash_table_t *h = &dbuf_hash_table;
+ int i;
+
+ /*
+ * The hash table is big enough to fill all of physical memory
+ * with an average block size of zfs_arc_average_blocksize (default 8K).
+ * By default, the table will take up
+ * totalmem * sizeof(void*) / 8K (1MB per GB with 8-byte pointers).
+ */
+ while (hsize * zfs_arc_average_blocksize < physmem * PAGESIZE)
+ hsize <<= 1;
+
+retry:
+ h->hash_table_mask = hsize - 1;
+#if defined(_KERNEL)
+ /*
+ * Large allocations which do not require contiguous pages
+ * should be using vmem_alloc() in the linux kernel
+ */
+ h->hash_table = vmem_zalloc(hsize * sizeof (void *), KM_SLEEP);
+#else
+ h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
+#endif
+ if (h->hash_table == NULL) {
+ /* XXX - we should really return an error instead of assert */
+ ASSERT(hsize > (1ULL << 10));
+ hsize >>= 1;
+ goto retry;
+ }
+
+ dbuf_kmem_cache = kmem_cache_create("dmu_buf_impl_t",
+ sizeof (dmu_buf_impl_t),
+ 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
+
+ for (i = 0; i < DBUF_MUTEXES; i++)
+ mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
+
+ dbuf_stats_init(h);
+
+ /*
+ * All entries are queued via taskq_dispatch_ent(), so min/maxalloc
+ * configuration is not required.
+ */
+ dbu_evict_taskq = taskq_create("dbu_evict", 1, defclsyspri, 0, 0, 0);
+
+ for (dbuf_cached_state_t dcs = 0; dcs < DB_CACHE_MAX; dcs++) {
+ dbuf_caches[dcs].cache =
+ multilist_create(sizeof (dmu_buf_impl_t),
+ offsetof(dmu_buf_impl_t, db_cache_link),
+ dbuf_cache_multilist_index_func);
+ zfs_refcount_create(&dbuf_caches[dcs].size);
+ }
+
+ dbuf_evict_thread_exit = B_FALSE;
+ mutex_init(&dbuf_evict_lock, NULL, MUTEX_DEFAULT, NULL);
+ cv_init(&dbuf_evict_cv, NULL, CV_DEFAULT, NULL);
+ dbuf_cache_evict_thread = thread_create(NULL, 0, dbuf_evict_thread,
+ NULL, 0, &p0, TS_RUN, minclsyspri);
+
+ dbuf_ksp = kstat_create("zfs", 0, "dbufstats", "misc",
+ KSTAT_TYPE_NAMED, sizeof (dbuf_stats) / sizeof (kstat_named_t),
+ KSTAT_FLAG_VIRTUAL);
+ if (dbuf_ksp != NULL) {
+ for (i = 0; i < DN_MAX_LEVELS; i++) {
+ snprintf(dbuf_stats.cache_levels[i].name,
+ KSTAT_STRLEN, "cache_level_%d", i);
+ dbuf_stats.cache_levels[i].data_type =
+ KSTAT_DATA_UINT64;
+ snprintf(dbuf_stats.cache_levels_bytes[i].name,
+ KSTAT_STRLEN, "cache_level_%d_bytes", i);
+ dbuf_stats.cache_levels_bytes[i].data_type =
+ KSTAT_DATA_UINT64;
+ }
+ dbuf_ksp->ks_data = &dbuf_stats;
+ dbuf_ksp->ks_update = dbuf_kstat_update;
+ kstat_install(dbuf_ksp);
+ }
+}
+
+void
+dbuf_fini(void)
+{
+ dbuf_hash_table_t *h = &dbuf_hash_table;
+ int i;
+
+ dbuf_stats_destroy();
+
+ for (i = 0; i < DBUF_MUTEXES; i++)
+ mutex_destroy(&h->hash_mutexes[i]);
+#if defined(_KERNEL)
+ /*
+ * Large allocations which do not require contiguous pages
+ * should be using vmem_free() in the linux kernel
+ */
+ vmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
+#else
+ kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
+#endif
+ kmem_cache_destroy(dbuf_kmem_cache);
+ taskq_destroy(dbu_evict_taskq);
+
+ mutex_enter(&dbuf_evict_lock);
+ dbuf_evict_thread_exit = B_TRUE;
+ while (dbuf_evict_thread_exit) {
+ cv_signal(&dbuf_evict_cv);
+ cv_wait(&dbuf_evict_cv, &dbuf_evict_lock);
+ }
+ mutex_exit(&dbuf_evict_lock);
+
+ mutex_destroy(&dbuf_evict_lock);
+ cv_destroy(&dbuf_evict_cv);
+
+ for (dbuf_cached_state_t dcs = 0; dcs < DB_CACHE_MAX; dcs++) {
+ zfs_refcount_destroy(&dbuf_caches[dcs].size);
+ multilist_destroy(dbuf_caches[dcs].cache);
+ }
+
+ if (dbuf_ksp != NULL) {
+ kstat_delete(dbuf_ksp);
+ dbuf_ksp = NULL;
+ }
+}
+
+/*
+ * Other stuff.
+ */
+
+#ifdef ZFS_DEBUG
+static void
+dbuf_verify(dmu_buf_impl_t *db)
+{
+ dnode_t *dn;
+ dbuf_dirty_record_t *dr;
+ uint32_t txg_prev;
+
+ ASSERT(MUTEX_HELD(&db->db_mtx));
+
+ if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
+ return;
+
+ ASSERT(db->db_objset != NULL);
+ DB_DNODE_ENTER(db);
+ dn = DB_DNODE(db);
+ if (dn == NULL) {
+ ASSERT(db->db_parent == NULL);
+ ASSERT(db->db_blkptr == NULL);
+ } else {
+ ASSERT3U(db->db.db_object, ==, dn->dn_object);
+ ASSERT3P(db->db_objset, ==, dn->dn_objset);
+ ASSERT3U(db->db_level, <, dn->dn_nlevels);
+ ASSERT(db->db_blkid == DMU_BONUS_BLKID ||
+ db->db_blkid == DMU_SPILL_BLKID ||
+ !avl_is_empty(&dn->dn_dbufs));
+ }
+ if (db->db_blkid == DMU_BONUS_BLKID) {
+ ASSERT(dn != NULL);
+ ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
+ ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
+ } else if (db->db_blkid == DMU_SPILL_BLKID) {
+ ASSERT(dn != NULL);
+ ASSERT0(db->db.db_offset);
+ } else {
+ ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
+ }
+
+ if ((dr = list_head(&db->db_dirty_records)) != NULL) {
+ ASSERT(dr->dr_dbuf == db);
+ txg_prev = dr->dr_txg;
+ for (dr = list_next(&db->db_dirty_records, dr); dr != NULL;
+ dr = list_next(&db->db_dirty_records, dr)) {
+ ASSERT(dr->dr_dbuf == db);
+ ASSERT(txg_prev > dr->dr_txg);
+ txg_prev = dr->dr_txg;
+ }
+ }
+
+ /*
+ * We can't assert that db_size matches dn_datablksz because it
+ * can be momentarily different when another thread is doing
+ * dnode_set_blksz().
+ */
+ if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
+ dr = db->db_data_pending;
+ /*
+ * It should only be modified in syncing context, so
+ * make sure we only have one copy of the data.
+ */
+ ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
+ }
+
+ /* verify db->db_blkptr */
+ if (db->db_blkptr) {
+ if (db->db_parent == dn->dn_dbuf) {
+ /* db is pointed to by the dnode */
+ /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
+ if (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
+ ASSERT(db->db_parent == NULL);
+ else
+ ASSERT(db->db_parent != NULL);
+ if (db->db_blkid != DMU_SPILL_BLKID)
+ ASSERT3P(db->db_blkptr, ==,
+ &dn->dn_phys->dn_blkptr[db->db_blkid]);
+ } else {
+ /* db is pointed to by an indirect block */
+ int epb __maybe_unused = db->db_parent->db.db_size >>
+ SPA_BLKPTRSHIFT;
+ ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
+ ASSERT3U(db->db_parent->db.db_object, ==,
+ db->db.db_object);
+ /*
+ * dnode_grow_indblksz() can make this fail if we don't
+ * have the parent's rwlock. XXX indblksz no longer
+ * grows. safe to do this now?
+ */
+ if (RW_LOCK_HELD(&db->db_parent->db_rwlock)) {
+ ASSERT3P(db->db_blkptr, ==,
+ ((blkptr_t *)db->db_parent->db.db_data +
+ db->db_blkid % epb));
+ }
+ }
+ }
+ if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
+ (db->db_buf == NULL || db->db_buf->b_data) &&
+ db->db.db_data && db->db_blkid != DMU_BONUS_BLKID &&
+ db->db_state != DB_FILL && !dn->dn_free_txg) {
+ /*
+ * If the blkptr isn't set but they have nonzero data,
+ * it had better be dirty, otherwise we'll lose that
+ * data when we evict this buffer.
+ *
+ * There is an exception to this rule for indirect blocks; in
+ * this case, if the indirect block is a hole, we fill in a few
+ * fields on each of the child blocks (importantly, birth time)
+ * to prevent hole birth times from being lost when you
+ * partially fill in a hole.
+ */
+ if (db->db_dirtycnt == 0) {
+ if (db->db_level == 0) {
+ uint64_t *buf = db->db.db_data;
+ int i;
+
+ for (i = 0; i < db->db.db_size >> 3; i++) {
+ ASSERT(buf[i] == 0);
+ }
+ } else {
+ blkptr_t *bps = db->db.db_data;
+ ASSERT3U(1 << DB_DNODE(db)->dn_indblkshift, ==,
+ db->db.db_size);
+ /*
+ * We want to verify that all the blkptrs in the
+ * indirect block are holes, but we may have
+ * automatically set up a few fields for them.
+ * We iterate through each blkptr and verify
+ * they only have those fields set.
+ */
+ for (int i = 0;
+ i < db->db.db_size / sizeof (blkptr_t);
+ i++) {
+ blkptr_t *bp = &bps[i];
+ ASSERT(ZIO_CHECKSUM_IS_ZERO(
+ &bp->blk_cksum));
+ ASSERT(
+ DVA_IS_EMPTY(&bp->blk_dva[0]) &&
+ DVA_IS_EMPTY(&bp->blk_dva[1]) &&
+ DVA_IS_EMPTY(&bp->blk_dva[2]));
+ ASSERT0(bp->blk_fill);
+ ASSERT0(bp->blk_pad[0]);
+ ASSERT0(bp->blk_pad[1]);
+ ASSERT(!BP_IS_EMBEDDED(bp));
+ ASSERT(BP_IS_HOLE(bp));
+ ASSERT0(bp->blk_phys_birth);
+ }
+ }
+ }
+ }
+ DB_DNODE_EXIT(db);
+}
+#endif
+
+static void
+dbuf_clear_data(dmu_buf_impl_t *db)
+{
+ ASSERT(MUTEX_HELD(&db->db_mtx));
+ dbuf_evict_user(db);
+ ASSERT3P(db->db_buf, ==, NULL);
+ db->db.db_data = NULL;
+ if (db->db_state != DB_NOFILL) {
+ db->db_state = DB_UNCACHED;
+ DTRACE_SET_STATE(db, "clear data");
+ }
+}
+
+static void
+dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
+{
+ ASSERT(MUTEX_HELD(&db->db_mtx));
+ ASSERT(buf != NULL);
+
+ db->db_buf = buf;
+ ASSERT(buf->b_data != NULL);
+ db->db.db_data = buf->b_data;
+}
+
+static arc_buf_t *
+dbuf_alloc_arcbuf_from_arcbuf(dmu_buf_impl_t *db, arc_buf_t *data)
+{
+ objset_t *os = db->db_objset;
+ spa_t *spa = os->os_spa;
+ arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
+ enum zio_compress compress_type;
+ uint8_t complevel;
+ int psize, lsize;
+
+ psize = arc_buf_size(data);
+ lsize = arc_buf_lsize(data);
+ compress_type = arc_get_compression(data);
+ complevel = arc_get_complevel(data);
+
+ if (arc_is_encrypted(data)) {
+ boolean_t byteorder;
+ uint8_t salt[ZIO_DATA_SALT_LEN];
+ uint8_t iv[ZIO_DATA_IV_LEN];
+ uint8_t mac[ZIO_DATA_MAC_LEN];
+ dnode_t *dn = DB_DNODE(db);
+
+ arc_get_raw_params(data, &byteorder, salt, iv, mac);
+ data = arc_alloc_raw_buf(spa, db, dmu_objset_id(os),
+ byteorder, salt, iv, mac, dn->dn_type, psize, lsize,
+ compress_type, complevel);
+ } else if (compress_type != ZIO_COMPRESS_OFF) {
+ ASSERT3U(type, ==, ARC_BUFC_DATA);
+ data = arc_alloc_compressed_buf(spa, db,
+ psize, lsize, compress_type, complevel);
+ } else {
+ data = arc_alloc_buf(spa, db, type, psize);
+ }
+ return (data);
+}
+
+static arc_buf_t *
+dbuf_alloc_arcbuf(dmu_buf_impl_t *db)
+{
+ spa_t *spa = db->db_objset->os_spa;
+
+ return (arc_alloc_buf(spa, db, DBUF_GET_BUFC_TYPE(db), db->db.db_size));
+}
+
+/*
+ * Loan out an arc_buf for read. Return the loaned arc_buf.
+ */
+arc_buf_t *
+dbuf_loan_arcbuf(dmu_buf_impl_t *db)
+{
+ arc_buf_t *abuf;
+
+ ASSERT(db->db_blkid != DMU_BONUS_BLKID);
+ mutex_enter(&db->db_mtx);
+ if (arc_released(db->db_buf) || zfs_refcount_count(&db->db_holds) > 1) {
+ int blksz = db->db.db_size;
+ spa_t *spa = db->db_objset->os_spa;
+
+ mutex_exit(&db->db_mtx);
+ abuf = arc_loan_buf(spa, B_FALSE, blksz);
+ bcopy(db->db.db_data, abuf->b_data, blksz);
+ } else {
+ abuf = db->db_buf;
+ arc_loan_inuse_buf(abuf, db);
+ db->db_buf = NULL;
+ dbuf_clear_data(db);
+ mutex_exit(&db->db_mtx);
+ }
+ return (abuf);
+}
+
+/*
+ * Calculate which level n block references the data at the level 0 offset
+ * provided.
+ */
+uint64_t
+dbuf_whichblock(const dnode_t *dn, const int64_t level, const uint64_t offset)
+{
+ if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) {
+ /*
+ * The level n blkid is equal to the level 0 blkid divided by
+ * the number of level 0s in a level n block.
+ *
+ * The level 0 blkid is offset >> datablkshift =
+ * offset / 2^datablkshift.
+ *
+ * The number of level 0s in a level n is the number of block
+ * pointers in an indirect block, raised to the power of level.
+ * This is 2^(indblkshift - SPA_BLKPTRSHIFT)^level =
+ * 2^(level*(indblkshift - SPA_BLKPTRSHIFT)).
+ *
+ * Thus, the level n blkid is: offset /
+ * ((2^datablkshift)*(2^(level*(indblkshift-SPA_BLKPTRSHIFT))))
+ * = offset / 2^(datablkshift + level *
+ * (indblkshift - SPA_BLKPTRSHIFT))
+ * = offset >> (datablkshift + level *
+ * (indblkshift - SPA_BLKPTRSHIFT))
+ */
+
+ const unsigned exp = dn->dn_datablkshift +
+ level * (dn->dn_indblkshift - SPA_BLKPTRSHIFT);
+
+ if (exp >= 8 * sizeof (offset)) {
+ /* This only happens on the highest indirection level */
+ ASSERT3U(level, ==, dn->dn_nlevels - 1);
+ return (0);
+ }
+
+ ASSERT3U(exp, <, 8 * sizeof (offset));
+
+ return (offset >> exp);
+ } else {
+ ASSERT3U(offset, <, dn->dn_datablksz);
+ return (0);
+ }
+}
+
+/*
+ * This function is used to lock the parent of the provided dbuf. This should be
+ * used when modifying or reading db_blkptr.
+ */
+db_lock_type_t
+dmu_buf_lock_parent(dmu_buf_impl_t *db, krw_t rw, void *tag)
+{
+ enum db_lock_type ret = DLT_NONE;
+ if (db->db_parent != NULL) {
+ rw_enter(&db->db_parent->db_rwlock, rw);
+ ret = DLT_PARENT;
+ } else if (dmu_objset_ds(db->