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Diffstat (limited to 'sys/contrib/openzfs/module/os/freebsd/zfs/abd_os.c')
-rw-r--r--sys/contrib/openzfs/module/os/freebsd/zfs/abd_os.c487
1 files changed, 487 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/abd_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/abd_os.c
new file mode 100644
index 000000000000..ff4d80ef1dfd
--- /dev/null
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/abd_os.c
@@ -0,0 +1,487 @@
+/*
+ * 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.
+ */
+
+/*
+ * Copyright (c) 2014 by Chunwei Chen. All rights reserved.
+ * Copyright (c) 2016 by Delphix. All rights reserved.
+ */
+
+/*
+ * See abd.c for a general overview of the arc buffered data (ABD).
+ *
+ * Using a large proportion of scattered ABDs decreases ARC fragmentation since
+ * when we are at the limit of allocatable space, using equal-size chunks will
+ * allow us to quickly reclaim enough space for a new large allocation (assuming
+ * it is also scattered).
+ *
+ * ABDs are allocated scattered by default unless the caller uses
+ * abd_alloc_linear() or zfs_abd_scatter_enabled is disabled.
+ */
+
+#include <sys/abd_impl.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/zio.h>
+#include <sys/zfs_context.h>
+#include <sys/zfs_znode.h>
+
+typedef struct abd_stats {
+ kstat_named_t abdstat_struct_size;
+ kstat_named_t abdstat_scatter_cnt;
+ kstat_named_t abdstat_scatter_data_size;
+ kstat_named_t abdstat_scatter_chunk_waste;
+ kstat_named_t abdstat_linear_cnt;
+ kstat_named_t abdstat_linear_data_size;
+} abd_stats_t;
+
+static abd_stats_t abd_stats = {
+ /* Amount of memory occupied by all of the abd_t struct allocations */
+ { "struct_size", KSTAT_DATA_UINT64 },
+ /*
+ * The number of scatter ABDs which are currently allocated, excluding
+ * ABDs which don't own their data (for instance the ones which were
+ * allocated through abd_get_offset()).
+ */
+ { "scatter_cnt", KSTAT_DATA_UINT64 },
+ /* Amount of data stored in all scatter ABDs tracked by scatter_cnt */
+ { "scatter_data_size", KSTAT_DATA_UINT64 },
+ /*
+ * The amount of space wasted at the end of the last chunk across all
+ * scatter ABDs tracked by scatter_cnt.
+ */
+ { "scatter_chunk_waste", KSTAT_DATA_UINT64 },
+ /*
+ * The number of linear ABDs which are currently allocated, excluding
+ * ABDs which don't own their data (for instance the ones which were
+ * allocated through abd_get_offset() and abd_get_from_buf()). If an
+ * ABD takes ownership of its buf then it will become tracked.
+ */
+ { "linear_cnt", KSTAT_DATA_UINT64 },
+ /* Amount of data stored in all linear ABDs tracked by linear_cnt */
+ { "linear_data_size", KSTAT_DATA_UINT64 },
+};
+
+/*
+ * The size of the chunks ABD allocates. Because the sizes allocated from the
+ * kmem_cache can't change, this tunable can only be modified at boot. Changing
+ * it at runtime would cause ABD iteration to work incorrectly for ABDs which
+ * were allocated with the old size, so a safeguard has been put in place which
+ * will cause the machine to panic if you change it and try to access the data
+ * within a scattered ABD.
+ */
+size_t zfs_abd_chunk_size = 4096;
+
+#if defined(_KERNEL)
+SYSCTL_DECL(_vfs_zfs);
+
+SYSCTL_INT(_vfs_zfs, OID_AUTO, abd_scatter_enabled, CTLFLAG_RWTUN,
+ &zfs_abd_scatter_enabled, 0, "Enable scattered ARC data buffers");
+SYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_chunk_size, CTLFLAG_RDTUN,
+ &zfs_abd_chunk_size, 0, "The size of the chunks ABD allocates");
+#endif
+
+kmem_cache_t *abd_chunk_cache;
+static kstat_t *abd_ksp;
+
+/*
+ * We use a scattered SPA_MAXBLOCKSIZE sized ABD whose chunks are
+ * just a single zero'd sized zfs_abd_chunk_size buffer. This
+ * allows us to conserve memory by only using a single zero buffer
+ * for the scatter chunks.
+ */
+abd_t *abd_zero_scatter = NULL;
+static char *abd_zero_buf = NULL;
+
+static void
+abd_free_chunk(void *c)
+{
+ kmem_cache_free(abd_chunk_cache, c);
+}
+
+static uint_t
+abd_chunkcnt_for_bytes(size_t size)
+{
+ return (P2ROUNDUP(size, zfs_abd_chunk_size) / zfs_abd_chunk_size);
+}
+
+static inline uint_t
+abd_scatter_chunkcnt(abd_t *abd)
+{
+ ASSERT(!abd_is_linear(abd));
+ return (abd_chunkcnt_for_bytes(
+ ABD_SCATTER(abd).abd_offset + abd->abd_size));
+}
+
+boolean_t
+abd_size_alloc_linear(size_t size)
+{
+ return (size <= zfs_abd_chunk_size ? B_TRUE : B_FALSE);
+}
+
+void
+abd_update_scatter_stats(abd_t *abd, abd_stats_op_t op)
+{
+ uint_t n = abd_scatter_chunkcnt(abd);
+ ASSERT(op == ABDSTAT_INCR || op == ABDSTAT_DECR);
+ int waste = n * zfs_abd_chunk_size - abd->abd_size;
+ if (op == ABDSTAT_INCR) {
+ ABDSTAT_BUMP(abdstat_scatter_cnt);
+ ABDSTAT_INCR(abdstat_scatter_data_size, abd->abd_size);
+ ABDSTAT_INCR(abdstat_scatter_chunk_waste, waste);
+ arc_space_consume(waste, ARC_SPACE_ABD_CHUNK_WASTE);
+ } else {
+ ABDSTAT_BUMPDOWN(abdstat_scatter_cnt);
+ ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size);
+ ABDSTAT_INCR(abdstat_scatter_chunk_waste, -waste);
+ arc_space_return(waste, ARC_SPACE_ABD_CHUNK_WASTE);
+ }
+}
+
+void
+abd_update_linear_stats(abd_t *abd, abd_stats_op_t op)
+{
+ ASSERT(op == ABDSTAT_INCR || op == ABDSTAT_DECR);
+ if (op == ABDSTAT_INCR) {
+ ABDSTAT_BUMP(abdstat_linear_cnt);
+ ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size);
+ } else {
+ ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
+ ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
+ }
+}
+
+void
+abd_verify_scatter(abd_t *abd)
+{
+ uint_t i, n;
+
+ /*
+ * There is no scatter linear pages in FreeBSD so there is an
+ * if an error if the ABD has been marked as a linear page.
+ */
+ ASSERT(!abd_is_linear_page(abd));
+ ASSERT3U(ABD_SCATTER(abd).abd_offset, <,
+ zfs_abd_chunk_size);
+ n = abd_scatter_chunkcnt(abd);
+ for (i = 0; i < n; i++) {
+ ASSERT3P(ABD_SCATTER(abd).abd_chunks[i], !=, NULL);
+ }
+}
+
+void
+abd_alloc_chunks(abd_t *abd, size_t size)
+{
+ uint_t i, n;
+
+ n = abd_chunkcnt_for_bytes(size);
+ for (i = 0; i < n; i++) {
+ void *c = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE);
+ ASSERT3P(c, !=, NULL);
+ ABD_SCATTER(abd).abd_chunks[i] = c;
+ }
+ ABD_SCATTER(abd).abd_chunk_size = zfs_abd_chunk_size;
+}
+
+void
+abd_free_chunks(abd_t *abd)
+{
+ uint_t i, n;
+
+ n = abd_scatter_chunkcnt(abd);
+ for (i = 0; i < n; i++) {
+ abd_free_chunk(ABD_SCATTER(abd).abd_chunks[i]);
+ }
+}
+
+abd_t *
+abd_alloc_struct_impl(size_t size)
+{
+ uint_t chunkcnt = abd_chunkcnt_for_bytes(size);
+ /*
+ * In the event we are allocating a gang ABD, the size passed in
+ * will be 0. We must make sure to set abd_size to the size of an
+ * ABD struct as opposed to an ABD scatter with 0 chunks. The gang
+ * ABD struct allocation accounts for an additional 24 bytes over
+ * a scatter ABD with 0 chunks.
+ */
+ size_t abd_size = MAX(sizeof (abd_t),
+ offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]));
+ abd_t *abd = kmem_alloc(abd_size, KM_PUSHPAGE);
+ ASSERT3P(abd, !=, NULL);
+ ABDSTAT_INCR(abdstat_struct_size, abd_size);
+
+ return (abd);
+}
+
+void
+abd_free_struct_impl(abd_t *abd)
+{
+ uint_t chunkcnt = abd_is_linear(abd) || abd_is_gang(abd) ? 0 :
+ abd_scatter_chunkcnt(abd);
+ ssize_t size = MAX(sizeof (abd_t),
+ offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]));
+ kmem_free(abd, size);
+ ABDSTAT_INCR(abdstat_struct_size, -size);
+}
+
+/*
+ * Allocate scatter ABD of size SPA_MAXBLOCKSIZE, where
+ * each chunk in the scatterlist will be set to abd_zero_buf.
+ */
+static void
+abd_alloc_zero_scatter(void)
+{
+ uint_t i, n;
+
+ n = abd_chunkcnt_for_bytes(SPA_MAXBLOCKSIZE);
+ abd_zero_buf = kmem_zalloc(zfs_abd_chunk_size, KM_SLEEP);
+ abd_zero_scatter = abd_alloc_struct(SPA_MAXBLOCKSIZE);
+
+ abd_zero_scatter->abd_flags |= ABD_FLAG_OWNER | ABD_FLAG_ZEROS;
+ abd_zero_scatter->abd_size = SPA_MAXBLOCKSIZE;
+
+ ABD_SCATTER(abd_zero_scatter).abd_offset = 0;
+ ABD_SCATTER(abd_zero_scatter).abd_chunk_size =
+ zfs_abd_chunk_size;
+
+ for (i = 0; i < n; i++) {
+ ABD_SCATTER(abd_zero_scatter).abd_chunks[i] =
+ abd_zero_buf;
+ }
+
+ ABDSTAT_BUMP(abdstat_scatter_cnt);
+ ABDSTAT_INCR(abdstat_scatter_data_size, zfs_abd_chunk_size);
+}
+
+static void
+abd_free_zero_scatter(void)
+{
+ ABDSTAT_BUMPDOWN(abdstat_scatter_cnt);
+ ABDSTAT_INCR(abdstat_scatter_data_size, -(int)zfs_abd_chunk_size);
+
+ abd_free_struct(abd_zero_scatter);
+ abd_zero_scatter = NULL;
+ kmem_free(abd_zero_buf, zfs_abd_chunk_size);
+}
+
+void
+abd_init(void)
+{
+ abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0,
+ NULL, NULL, NULL, NULL, 0, KMC_NODEBUG);
+
+ abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED,
+ sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
+ if (abd_ksp != NULL) {
+ abd_ksp->ks_data = &abd_stats;
+ kstat_install(abd_ksp);
+ }
+
+ abd_alloc_zero_scatter();
+}
+
+void
+abd_fini(void)
+{
+ abd_free_zero_scatter();
+
+ if (abd_ksp != NULL) {
+ kstat_delete(abd_ksp);
+ abd_ksp = NULL;
+ }
+
+ kmem_cache_destroy(abd_chunk_cache);
+ abd_chunk_cache = NULL;
+}
+
+void
+abd_free_linear_page(abd_t *abd)
+{
+ /*
+ * FreeBSD does not have have scatter linear pages
+ * so there is an error.
+ */
+ VERIFY(0);
+}
+
+/*
+ * If we're going to use this ABD for doing I/O using the block layer, the
+ * consumer of the ABD data doesn't care if it's scattered or not, and we don't
+ * plan to store this ABD in memory for a long period of time, we should
+ * allocate the ABD type that requires the least data copying to do the I/O.
+ *
+ * Currently this is linear ABDs, however if ldi_strategy() can ever issue I/Os
+ * using a scatter/gather list we should switch to that and replace this call
+ * with vanilla abd_alloc().
+ */
+abd_t *
+abd_alloc_for_io(size_t size, boolean_t is_metadata)
+{
+ return (abd_alloc_linear(size, is_metadata));
+}
+
+abd_t *
+abd_get_offset_scatter(abd_t *abd, abd_t *sabd, size_t off)
+{
+ abd_verify(sabd);
+ ASSERT3U(off, <=, sabd->abd_size);
+
+ size_t new_offset = ABD_SCATTER(sabd).abd_offset + off;
+ uint_t chunkcnt = abd_scatter_chunkcnt(sabd) -
+ (new_offset / zfs_abd_chunk_size);
+
+ /*
+ * If an abd struct is provided, it is only the minimum size. If we
+ * need additional chunks, we need to allocate a new struct.
+ */
+ if (abd != NULL &&
+ offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]) >
+ sizeof (abd_t)) {
+ abd = NULL;
+ }
+
+ if (abd == NULL)
+ abd = abd_alloc_struct(chunkcnt * zfs_abd_chunk_size);
+
+ /*
+ * 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_SCATTER(abd).abd_offset = new_offset % zfs_abd_chunk_size;
+ ABD_SCATTER(abd).abd_chunk_size = zfs_abd_chunk_size;
+
+ /* Copy the scatterlist starting at the correct offset */
+ (void) memcpy(&ABD_SCATTER(abd).abd_chunks,
+ &ABD_SCATTER(sabd).abd_chunks[new_offset /
+ zfs_abd_chunk_size],
+ chunkcnt * sizeof (void *));
+
+ return (abd);
+}
+
+static inline size_t
+abd_iter_scatter_chunk_offset(struct abd_iter *aiter)
+{
+ ASSERT(!abd_is_linear(aiter->iter_abd));
+ return ((ABD_SCATTER(aiter->iter_abd).abd_offset +
+ aiter->iter_pos) % zfs_abd_chunk_size);
+}
+
+static inline size_t
+abd_iter_scatter_chunk_index(struct abd_iter *aiter)
+{
+ ASSERT(!abd_is_linear(aiter->iter_abd));
+ return ((ABD_SCATTER(aiter->iter_abd).abd_offset +
+ aiter->iter_pos) / zfs_abd_chunk_size);
+}
+
+/*
+ * Initialize the abd_iter.
+ */
+void
+abd_iter_init(struct abd_iter *aiter, abd_t *abd)
+{
+ ASSERT(!abd_is_gang(abd));
+ abd_verify(abd);
+ aiter->iter_abd = abd;
+ aiter->iter_pos = 0;
+ aiter->iter_mapaddr = NULL;
+ aiter->iter_mapsize = 0;
+}
+
+/*
+ * This is just a helper function to see if we have exhausted the
+ * abd_iter and reached the end.
+ */
+boolean_t
+abd_iter_at_end(struct abd_iter *aiter)
+{
+ return (aiter->iter_pos == aiter->iter_abd->abd_size);
+}
+
+/*
+ * Advance the iterator by a certain amount. Cannot be called when a chunk is
+ * in use. This can be safely called when the aiter has already exhausted, in
+ * which case this does nothing.
+ */
+void
+abd_iter_advance(struct abd_iter *aiter, size_t amount)
+{
+ ASSERT3P(aiter->iter_mapaddr, ==, NULL);
+ ASSERT0(aiter->iter_mapsize);
+
+ /* There's nothing left to advance to, so do nothing */
+ if (abd_iter_at_end(aiter))
+ return;
+
+ aiter->iter_pos += amount;
+}
+
+/*
+ * Map the current chunk into aiter. This can be safely called when the aiter
+ * has already exhausted, in which case this does nothing.
+ */
+void
+abd_iter_map(struct abd_iter *aiter)
+{
+ void *paddr;
+ size_t offset = 0;
+
+ ASSERT3P(aiter->iter_mapaddr, ==, NULL);
+ ASSERT0(aiter->iter_mapsize);
+
+ /* Panic if someone has changed zfs_abd_chunk_size */
+ IMPLY(!abd_is_linear(aiter->iter_abd), zfs_abd_chunk_size ==
+ ABD_SCATTER(aiter->iter_abd).abd_chunk_size);
+
+ /* There's nothing left to iterate over, so do nothing */
+ if (abd_iter_at_end(aiter))
+ return;
+
+ if (abd_is_linear(aiter->iter_abd)) {
+ offset = aiter->iter_pos;
+ aiter->iter_mapsize = aiter->iter_abd->abd_size - offset;
+ paddr = ABD_LINEAR_BUF(aiter->iter_abd);
+ } else {
+ size_t index = abd_iter_scatter_chunk_index(aiter);
+ offset = abd_iter_scatter_chunk_offset(aiter);
+ aiter->iter_mapsize = MIN(zfs_abd_chunk_size - offset,
+ aiter->iter_abd->abd_size - aiter->iter_pos);
+ paddr = ABD_SCATTER(aiter->iter_abd).abd_chunks[index];
+ }
+ aiter->iter_mapaddr = (char *)paddr + offset;
+}
+
+/*
+ * Unmap the current chunk from aiter. This can be safely called when the aiter
+ * has already exhausted, in which case this does nothing.
+ */
+void
+abd_iter_unmap(struct abd_iter *aiter)
+{
+ /* There's nothing left to unmap, so do nothing */
+ if (abd_iter_at_end(aiter))
+ return;
+
+ ASSERT3P(aiter->iter_mapaddr, !=, NULL);
+ ASSERT3U(aiter->iter_mapsize, >, 0);
+
+ aiter->iter_mapaddr = NULL;
+ aiter->iter_mapsize = 0;
+}
+
+void
+abd_cache_reap_now(void)
+{
+ kmem_cache_reap_soon(abd_chunk_cache);
+}