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Diffstat (limited to 'sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c')
| -rw-r--r-- | sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c | 3318 |
1 files changed, 3318 insertions, 0 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c new file mode 100644 index 000000000000..f31ac23ce703 --- /dev/null +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c @@ -0,0 +1,3318 @@ +/* + * 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) 2014 Integros [integros.com] + */ + +/* Portions Copyright 2010 Robert Milkowski */ + +#include <sys/zfs_context.h> +#include <sys/spa.h> +#include <sys/spa_impl.h> +#include <sys/dmu.h> +#include <sys/zap.h> +#include <sys/arc.h> +#include <sys/stat.h> +#include <sys/resource.h> +#include <sys/zil.h> +#include <sys/zil_impl.h> +#include <sys/dsl_dataset.h> +#include <sys/vdev_impl.h> +#include <sys/dmu_tx.h> +#include <sys/dsl_pool.h> +#include <sys/abd.h> + +/* + * The ZFS Intent Log (ZIL) saves "transaction records" (itxs) of system + * calls that change the file system. Each itx has enough information to + * be able to replay them after a system crash, power loss, or + * equivalent failure mode. These are stored in memory until either: + * + * 1. they are committed to the pool by the DMU transaction group + * (txg), at which point they can be discarded; or + * 2. they are committed to the on-disk ZIL for the dataset being + * modified (e.g. due to an fsync, O_DSYNC, or other synchronous + * requirement). + * + * In the event of a crash or power loss, the itxs contained by each + * dataset's on-disk ZIL will be replayed when that dataset is first + * instantianted (e.g. if the dataset is a normal fileystem, when it is + * first mounted). + * + * As hinted at above, there is one ZIL per dataset (both the in-memory + * representation, and the on-disk representation). The on-disk format + * consists of 3 parts: + * + * - a single, per-dataset, ZIL header; which points to a chain of + * - zero or more ZIL blocks; each of which contains + * - zero or more ZIL records + * + * A ZIL record holds the information necessary to replay a single + * system call transaction. A ZIL block can hold many ZIL records, and + * the blocks are chained together, similarly to a singly linked list. + * + * Each ZIL block contains a block pointer (blkptr_t) to the next ZIL + * block in the chain, and the ZIL header points to the first block in + * the chain. + * + * Note, there is not a fixed place in the pool to hold these ZIL + * blocks; they are dynamically allocated and freed as needed from the + * blocks available on the pool, though they can be preferentially + * allocated from a dedicated "log" vdev. + */ + +/* + * This controls the amount of time that a ZIL block (lwb) will remain + * "open" when it isn't "full", and it has a thread waiting for it to be + * committed to stable storage. Please refer to the zil_commit_waiter() + * function (and the comments within it) for more details. + */ +int zfs_commit_timeout_pct = 5; + +/* + * Disable intent logging replay. This global ZIL switch affects all pools. + */ +int zil_replay_disable = 0; +SYSCTL_DECL(_vfs_zfs); +SYSCTL_INT(_vfs_zfs, OID_AUTO, zil_replay_disable, CTLFLAG_RWTUN, + &zil_replay_disable, 0, "Disable intent logging replay"); + +/* + * Tunable parameter for debugging or performance analysis. Setting + * zfs_nocacheflush will cause corruption on power loss if a volatile + * out-of-order write cache is enabled. + */ +boolean_t zfs_nocacheflush = B_FALSE; +SYSCTL_INT(_vfs_zfs, OID_AUTO, cache_flush_disable, CTLFLAG_RWTUN, + &zfs_nocacheflush, 0, "Disable cache flush"); +boolean_t zfs_trim_enabled = B_TRUE; +SYSCTL_DECL(_vfs_zfs_trim); +SYSCTL_INT(_vfs_zfs_trim, OID_AUTO, enabled, CTLFLAG_RDTUN, &zfs_trim_enabled, 0, + "Enable ZFS TRIM"); + +/* + * Limit SLOG write size per commit executed with synchronous priority. + * Any writes above that will be executed with lower (asynchronous) priority + * to limit potential SLOG device abuse by single active ZIL writer. + */ +uint64_t zil_slog_bulk = 768 * 1024; +SYSCTL_QUAD(_vfs_zfs, OID_AUTO, zil_slog_bulk, CTLFLAG_RWTUN, + &zil_slog_bulk, 0, "Maximal SLOG commit size with sync priority"); + +static kmem_cache_t *zil_lwb_cache; +static kmem_cache_t *zil_zcw_cache; + +#define LWB_EMPTY(lwb) ((BP_GET_LSIZE(&lwb->lwb_blk) - \ + sizeof (zil_chain_t)) == (lwb->lwb_sz - lwb->lwb_nused)) + +static int +zil_bp_compare(const void *x1, const void *x2) +{ + const dva_t *dva1 = &((zil_bp_node_t *)x1)->zn_dva; + const dva_t *dva2 = &((zil_bp_node_t *)x2)->zn_dva; + + int cmp = AVL_CMP(DVA_GET_VDEV(dva1), DVA_GET_VDEV(dva2)); + if (likely(cmp)) + return (cmp); + + return (AVL_CMP(DVA_GET_OFFSET(dva1), DVA_GET_OFFSET(dva2))); +} + +static void +zil_bp_tree_init(zilog_t *zilog) +{ + avl_create(&zilog->zl_bp_tree, zil_bp_compare, + sizeof (zil_bp_node_t), offsetof(zil_bp_node_t, zn_node)); +} + +static void +zil_bp_tree_fini(zilog_t *zilog) +{ + avl_tree_t *t = &zilog->zl_bp_tree; + zil_bp_node_t *zn; + void *cookie = NULL; + + while ((zn = avl_destroy_nodes(t, &cookie)) != NULL) + kmem_free(zn, sizeof (zil_bp_node_t)); + + avl_destroy(t); +} + +int +zil_bp_tree_add(zilog_t *zilog, const blkptr_t *bp) +{ + avl_tree_t *t = &zilog->zl_bp_tree; + const dva_t *dva; + zil_bp_node_t *zn; + avl_index_t where; + + if (BP_IS_EMBEDDED(bp)) + return (0); + + dva = BP_IDENTITY(bp); + + if (avl_find(t, dva, &where) != NULL) + return (SET_ERROR(EEXIST)); + + zn = kmem_alloc(sizeof (zil_bp_node_t), KM_SLEEP); + zn->zn_dva = *dva; + avl_insert(t, zn, where); + + return (0); +} + +static zil_header_t * +zil_header_in_syncing_context(zilog_t *zilog) +{ + return ((zil_header_t *)zilog->zl_header); +} + +static void +zil_init_log_chain(zilog_t *zilog, blkptr_t *bp) +{ + zio_cksum_t *zc = &bp->blk_cksum; + + zc->zc_word[ZIL_ZC_GUID_0] = spa_get_random(-1ULL); + zc->zc_word[ZIL_ZC_GUID_1] = spa_get_random(-1ULL); + zc->zc_word[ZIL_ZC_OBJSET] = dmu_objset_id(zilog->zl_os); + zc->zc_word[ZIL_ZC_SEQ] = 1ULL; +} + +/* + * Read a log block and make sure it's valid. + */ +static int +zil_read_log_block(zilog_t *zilog, const blkptr_t *bp, blkptr_t *nbp, void *dst, + char **end) +{ + enum zio_flag zio_flags = ZIO_FLAG_CANFAIL; + arc_flags_t aflags = ARC_FLAG_WAIT; + arc_buf_t *abuf = NULL; + zbookmark_phys_t zb; + int error; + + if (zilog->zl_header->zh_claim_txg == 0) + zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB; + + if (!(zilog->zl_header->zh_flags & ZIL_CLAIM_LR_SEQ_VALID)) + zio_flags |= ZIO_FLAG_SPECULATIVE; + + SET_BOOKMARK(&zb, bp->blk_cksum.zc_word[ZIL_ZC_OBJSET], + ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]); + + error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf, + ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb); + + if (error == 0) { + zio_cksum_t cksum = bp->blk_cksum; + + /* + * Validate the checksummed log block. + * + * Sequence numbers should be... sequential. The checksum + * verifier for the next block should be bp's checksum plus 1. + * + * Also check the log chain linkage and size used. + */ + cksum.zc_word[ZIL_ZC_SEQ]++; + + if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) { + zil_chain_t *zilc = abuf->b_data; + char *lr = (char *)(zilc + 1); + uint64_t len = zilc->zc_nused - sizeof (zil_chain_t); + + if (bcmp(&cksum, &zilc->zc_next_blk.blk_cksum, + sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk)) { + error = SET_ERROR(ECKSUM); + } else { + ASSERT3U(len, <=, SPA_OLD_MAXBLOCKSIZE); + bcopy(lr, dst, len); + *end = (char *)dst + len; + *nbp = zilc->zc_next_blk; + } + } else { + char *lr = abuf->b_data; + uint64_t size = BP_GET_LSIZE(bp); + zil_chain_t *zilc = (zil_chain_t *)(lr + size) - 1; + + if (bcmp(&cksum, &zilc->zc_next_blk.blk_cksum, + sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk) || + (zilc->zc_nused > (size - sizeof (*zilc)))) { + error = SET_ERROR(ECKSUM); + } else { + ASSERT3U(zilc->zc_nused, <=, + SPA_OLD_MAXBLOCKSIZE); + bcopy(lr, dst, zilc->zc_nused); + *end = (char *)dst + zilc->zc_nused; + *nbp = zilc->zc_next_blk; + } + } + + arc_buf_destroy(abuf, &abuf); + } + + return (error); +} + +/* + * Read a TX_WRITE log data block. + */ +static int +zil_read_log_data(zilog_t *zilog, const lr_write_t *lr, void *wbuf) +{ + enum zio_flag zio_flags = ZIO_FLAG_CANFAIL; + const blkptr_t *bp = &lr->lr_blkptr; + arc_flags_t aflags = ARC_FLAG_WAIT; + arc_buf_t *abuf = NULL; + zbookmark_phys_t zb; + int error; + + if (BP_IS_HOLE(bp)) { + if (wbuf != NULL) + bzero(wbuf, MAX(BP_GET_LSIZE(bp), lr->lr_length)); + return (0); + } + + if (zilog->zl_header->zh_claim_txg == 0) + zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB; + + SET_BOOKMARK(&zb, dmu_objset_id(zilog->zl_os), lr->lr_foid, + ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp)); + + error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf, + ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb); + + if (error == 0) { + if (wbuf != NULL) + bcopy(abuf->b_data, wbuf, arc_buf_size(abuf)); + arc_buf_destroy(abuf, &abuf); + } + + return (error); +} + +/* + * Parse the intent log, and call parse_func for each valid record within. + */ +int +zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func, + zil_parse_lr_func_t *parse_lr_func, void *arg, uint64_t txg) +{ + const zil_header_t *zh = zilog->zl_header; + boolean_t claimed = !!zh->zh_claim_txg; + uint64_t claim_blk_seq = claimed ? zh->zh_claim_blk_seq : UINT64_MAX; + uint64_t claim_lr_seq = claimed ? zh->zh_claim_lr_seq : UINT64_MAX; + uint64_t max_blk_seq = 0; + uint64_t max_lr_seq = 0; + uint64_t blk_count = 0; + uint64_t lr_count = 0; + blkptr_t blk, next_blk; + char *lrbuf, *lrp; + int error = 0; + + /* + * Old logs didn't record the maximum zh_claim_lr_seq. + */ + if (!(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID)) + claim_lr_seq = UINT64_MAX; + + /* + * Starting at the block pointed to by zh_log we read the log chain. + * For each block in the chain we strongly check that block to + * ensure its validity. We stop when an invalid block is found. + * For each block pointer in the chain we call parse_blk_func(). + * For each record in each valid block we call parse_lr_func(). + * If the log has been claimed, stop if we encounter a sequence + * number greater than the highest claimed sequence number. + */ + lrbuf = zio_buf_alloc(SPA_OLD_MAXBLOCKSIZE); + zil_bp_tree_init(zilog); + + for (blk = zh->zh_log; !BP_IS_HOLE(&blk); blk = next_blk) { + uint64_t blk_seq = blk.blk_cksum.zc_word[ZIL_ZC_SEQ]; + int reclen; + char *end; + + if (blk_seq > claim_blk_seq) + break; + if ((error = parse_blk_func(zilog, &blk, arg, txg)) != 0) + break; + ASSERT3U(max_blk_seq, <, blk_seq); + max_blk_seq = blk_seq; + blk_count++; + + if (max_lr_seq == claim_lr_seq && max_blk_seq == claim_blk_seq) + break; + + error = zil_read_log_block(zilog, &blk, &next_blk, lrbuf, &end); + if (error != 0) + break; + + for (lrp = lrbuf; lrp < end; lrp += reclen) { + lr_t *lr = (lr_t *)lrp; + reclen = lr->lrc_reclen; + ASSERT3U(reclen, >=, sizeof (lr_t)); + if (lr->lrc_seq > claim_lr_seq) + goto done; + if ((error = parse_lr_func(zilog, lr, arg, txg)) != 0) + goto done; + ASSERT3U(max_lr_seq, <, lr->lrc_seq); + max_lr_seq = lr->lrc_seq; + lr_count++; + } + } +done: + zilog->zl_parse_error = error; + zilog->zl_parse_blk_seq = max_blk_seq; + zilog->zl_parse_lr_seq = max_lr_seq; + zilog->zl_parse_blk_count = blk_count; + zilog->zl_parse_lr_count = lr_count; + + ASSERT(!claimed || !(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID) || + (max_blk_seq == claim_blk_seq && max_lr_seq == claim_lr_seq)); + + zil_bp_tree_fini(zilog); + zio_buf_free(lrbuf, SPA_OLD_MAXBLOCKSIZE); + + return (error); +} + +/* ARGSUSED */ +static int +zil_clear_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t first_txg) +{ + ASSERT(!BP_IS_HOLE(bp)); + + /* + * As we call this function from the context of a rewind to a + * checkpoint, each ZIL block whose txg is later than the txg + * that we rewind to is invalid. Thus, we return -1 so + * zil_parse() doesn't attempt to read it. + */ + if (bp->blk_birth >= first_txg) + return (-1); + + if (zil_bp_tree_add(zilog, bp) != 0) + return (0); + + zio_free(zilog->zl_spa, first_txg, bp); + return (0); +} + +/* ARGSUSED */ +static int +zil_noop_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t first_txg) +{ + return (0); +} + +static int +zil_claim_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t first_txg) +{ + /* + * Claim log block if not already committed and not already claimed. + * If tx == NULL, just verify that the block is claimable. + */ + if (BP_IS_HOLE(bp) || bp->blk_birth < first_txg || + zil_bp_tree_add(zilog, bp) != 0) + return (0); + + return (zio_wait(zio_claim(NULL, zilog->zl_spa, + tx == NULL ? 0 : first_txg, bp, spa_claim_notify, NULL, + ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB))); +} + +static int +zil_claim_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t first_txg) +{ + lr_write_t *lr = (lr_write_t *)lrc; + int error; + + if (lrc->lrc_txtype != TX_WRITE) + return (0); + + /* + * If the block is not readable, don't claim it. This can happen + * in normal operation when a log block is written to disk before + * some of the dmu_sync() blocks it points to. In this case, the + * transaction cannot have been committed to anyone (we would have + * waited for all writes to be stable first), so it is semantically + * correct to declare this the end of the log. + */ + if (lr->lr_blkptr.blk_birth >= first_txg && + (error = zil_read_log_data(zilog, lr, NULL)) != 0) + return (error); + return (zil_claim_log_block(zilog, &lr->lr_blkptr, tx, first_txg)); +} + +/* ARGSUSED */ +static int +zil_free_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t claim_txg) +{ + zio_free(zilog->zl_spa, dmu_tx_get_txg(tx), bp); + + return (0); +} + +static int +zil_free_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t claim_txg) +{ + lr_write_t *lr = (lr_write_t *)lrc; + blkptr_t *bp = &lr->lr_blkptr; + + /* + * If we previously claimed it, we need to free it. + */ + if (claim_txg != 0 && lrc->lrc_txtype == TX_WRITE && + bp->blk_birth >= claim_txg && zil_bp_tree_add(zilog, bp) == 0 && + !BP_IS_HOLE(bp)) + zio_free(zilog->zl_spa, dmu_tx_get_txg(tx), bp); + + return (0); +} + +static int +zil_lwb_vdev_compare(const void *x1, const void *x2) +{ + const uint64_t v1 = ((zil_vdev_node_t *)x1)->zv_vdev; + const uint64_t v2 = ((zil_vdev_node_t *)x2)->zv_vdev; + + return (AVL_CMP(v1, v2)); +} + +static lwb_t * +zil_alloc_lwb(zilog_t *zilog, blkptr_t *bp, boolean_t slog, uint64_t txg) +{ + lwb_t *lwb; + + lwb = kmem_cache_alloc(zil_lwb_cache, KM_SLEEP); + lwb->lwb_zilog = zilog; + lwb->lwb_blk = *bp; + lwb->lwb_slog = slog; + lwb->lwb_state = LWB_STATE_CLOSED; + lwb->lwb_buf = zio_buf_alloc(BP_GET_LSIZE(bp)); + lwb->lwb_max_txg = txg; + lwb->lwb_write_zio = NULL; + lwb->lwb_root_zio = NULL; + lwb->lwb_tx = NULL; + lwb->lwb_issued_timestamp = 0; + if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) { + lwb->lwb_nused = sizeof (zil_chain_t); + lwb->lwb_sz = BP_GET_LSIZE(bp); + } else { + lwb->lwb_nused = 0; + lwb->lwb_sz = BP_GET_LSIZE(bp) - sizeof (zil_chain_t); + } + + mutex_enter(&zilog->zl_lock); + list_insert_tail(&zilog->zl_lwb_list, lwb); + mutex_exit(&zilog->zl_lock); + + ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); + ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); + VERIFY(list_is_empty(&lwb->lwb_waiters)); + + return (lwb); +} + +static void +zil_free_lwb(zilog_t *zilog, lwb_t *lwb) +{ + ASSERT(MUTEX_HELD(&zilog->zl_lock)); + ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); + VERIFY(list_is_empty(&lwb->lwb_waiters)); + ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); + ASSERT3P(lwb->lwb_write_zio, ==, NULL); + ASSERT3P(lwb->lwb_root_zio, ==, NULL); + ASSERT3U(lwb->lwb_max_txg, <=, spa_syncing_txg(zilog->zl_spa)); + ASSERT(lwb->lwb_state == LWB_STATE_CLOSED || + lwb->lwb_state == LWB_STATE_DONE); + + /* + * Clear the zilog's field to indicate this lwb is no longer + * valid, and prevent use-after-free errors. + */ + if (zilog->zl_last_lwb_opened == lwb) + zilog->zl_last_lwb_opened = NULL; + + kmem_cache_free(zil_lwb_cache, lwb); +} + +/* + * Called when we create in-memory log transactions so that we know + * to cleanup the itxs at the end of spa_sync(). + */ +void +zilog_dirty(zilog_t *zilog, uint64_t txg) +{ + dsl_pool_t *dp = zilog->zl_dmu_pool; + dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os); + + ASSERT(spa_writeable(zilog->zl_spa)); + + if (ds->ds_is_snapshot) + panic("dirtying snapshot!"); + + if (txg_list_add(&dp->dp_dirty_zilogs, zilog, txg)) { + /* up the hold count until we can be written out */ + dmu_buf_add_ref(ds->ds_dbuf, zilog); + + zilog->zl_dirty_max_txg = MAX(txg, zilog->zl_dirty_max_txg); + } +} + +/* + * Determine if the zil is dirty in the specified txg. Callers wanting to + * ensure that the dirty state does not change must hold the itxg_lock for + * the specified txg. Holding the lock will ensure that the zil cannot be + * dirtied (zil_itx_assign) or cleaned (zil_clean) while we check its current + * state. + */ +boolean_t +zilog_is_dirty_in_txg(zilog_t *zilog, uint64_t txg) +{ + dsl_pool_t *dp = zilog->zl_dmu_pool; + + if (txg_list_member(&dp->dp_dirty_zilogs, zilog, txg & TXG_MASK)) + return (B_TRUE); + return (B_FALSE); +} + +/* + * Determine if the zil is dirty. The zil is considered dirty if it has + * any pending itx records that have not been cleaned by zil_clean(). + */ +boolean_t +zilog_is_dirty(zilog_t *zilog) +{ + dsl_pool_t *dp = zilog->zl_dmu_pool; + + for (int t = 0; t < TXG_SIZE; t++) { + if (txg_list_member(&dp->dp_dirty_zilogs, zilog, t)) + return (B_TRUE); + } + return (B_FALSE); +} + +/* + * Create an on-disk intent log. + */ +static lwb_t * +zil_create(zilog_t *zilog) +{ + const zil_header_t *zh = zilog->zl_header; + lwb_t *lwb = NULL; + uint64_t txg = 0; + dmu_tx_t *tx = NULL; + blkptr_t blk; + int error = 0; + boolean_t slog = FALSE; + + /* + * Wait for any previous destroy to complete. + */ + txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); + + ASSERT(zh->zh_claim_txg == 0); + ASSERT(zh->zh_replay_seq == 0); + + blk = zh->zh_log; + + /* + * Allocate an initial log block if: + * - there isn't one already + * - the existing block is the wrong endianess + */ + if (BP_IS_HOLE(&blk) || BP_SHOULD_BYTESWAP(&blk)) { + tx = dmu_tx_create(zilog->zl_os); + VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); + dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); + txg = dmu_tx_get_txg(tx); + + if (!BP_IS_HOLE(&blk)) { + zio_free(zilog->zl_spa, txg, &blk); + BP_ZERO(&blk); + } + + error = zio_alloc_zil(zilog->zl_spa, + zilog->zl_os->os_dsl_dataset->ds_object, txg, &blk, NULL, + ZIL_MIN_BLKSZ, &slog); + + if (error == 0) + zil_init_log_chain(zilog, &blk); + } + + /* + * Allocate a log write block (lwb) for the first log block. + */ + if (error == 0) + lwb = zil_alloc_lwb(zilog, &blk, slog, txg); + + /* + * If we just allocated the first log block, commit our transaction + * and wait for zil_sync() to stuff the block poiner into zh_log. + * (zh is part of the MOS, so we cannot modify it in open context.) + */ + if (tx != NULL) { + dmu_tx_commit(tx); + txg_wait_synced(zilog->zl_dmu_pool, txg); + } + + ASSERT(bcmp(&blk, &zh->zh_log, sizeof (blk)) == 0); + + return (lwb); +} + +/* + * In one tx, free all log blocks and clear the log header. If keep_first + * is set, then we're replaying a log with no content. We want to keep the + * first block, however, so that the first synchronous transaction doesn't + * require a txg_wait_synced() in zil_create(). We don't need to + * txg_wait_synced() here either when keep_first is set, because both + * zil_create() and zil_destroy() will wait for any in-progress destroys + * to complete. + */ +void +zil_destroy(zilog_t *zilog, boolean_t keep_first) +{ + const zil_header_t *zh = zilog->zl_header; + lwb_t *lwb; + dmu_tx_t *tx; + uint64_t txg; + + /* + * Wait for any previous destroy to complete. + */ + txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); + + zilog->zl_old_header = *zh; /* debugging aid */ + + if (BP_IS_HOLE(&zh->zh_log)) + return; + + tx = dmu_tx_create(zilog->zl_os); + VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); + dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); + txg = dmu_tx_get_txg(tx); + + mutex_enter(&zilog->zl_lock); + + ASSERT3U(zilog->zl_destroy_txg, <, txg); + zilog->zl_destroy_txg = txg; + zilog->zl_keep_first = keep_first; + + if (!list_is_empty(&zilog->zl_lwb_list)) { + ASSERT(zh->zh_claim_txg == 0); + VERIFY(!keep_first); + while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) { + list_remove(&zilog->zl_lwb_list, lwb); + if (lwb->lwb_buf != NULL) + zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); + zio_free(zilog->zl_spa, txg, &lwb->lwb_blk); + zil_free_lwb(zilog, lwb); + } + } else if (!keep_first) { + zil_destroy_sync(zilog, tx); + } + mutex_exit(&zilog->zl_lock); + + dmu_tx_commit(tx); +} + +void +zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx) +{ + ASSERT(list_is_empty(&zilog->zl_lwb_list)); + (void) zil_parse(zilog, zil_free_log_block, + zil_free_log_record, tx, zilog->zl_header->zh_claim_txg); +} + +int +zil_claim(dsl_pool_t *dp, dsl_dataset_t *ds, void *txarg) +{ + dmu_tx_t *tx = txarg; + zilog_t *zilog; + uint64_t first_txg; + zil_header_t *zh; + objset_t *os; + int error; + + error = dmu_objset_own_obj(dp, ds->ds_object, + DMU_OST_ANY, B_FALSE, FTAG, &os); + if (error != 0) { + /* + * EBUSY indicates that the objset is inconsistent, in which + * case it can not have a ZIL. + */ + if (error != EBUSY) { + cmn_err(CE_WARN, "can't open objset for %llu, error %u", + (unsigned long long)ds->ds_object, error); + } + return (0); + } + + zilog = dmu_objset_zil(os); + zh = zil_header_in_syncing_context(zilog); + ASSERT3U(tx->tx_txg, ==, spa_first_txg(zilog->zl_spa)); + first_txg = spa_min_claim_txg(zilog->zl_spa); + + /* + * If the spa_log_state is not set to be cleared, check whether + * the current uberblock is a checkpoint one and if the current + * header has been claimed before moving on. + * + * If the current uberblock is a checkpointed uberblock then + * one of the following scenarios took place: + * + * 1] We are currently rewinding to the checkpoint of the pool. + * 2] We crashed in the middle of a checkpoint rewind but we + * did manage to write the checkpointed uberblock to the + * vdev labels, so when we tried to import the pool again + * the checkpointed uberblock was selected from the import + * procedure. + * + * In both cases we want to zero out all the ZIL blocks, except + * the ones that have been claimed at the time of the checkpoint + * (their zh_claim_txg != 0). The reason is that these blocks + * may be corrupted since we may have reused their locations on + * disk after we took the checkpoint. + * + * We could try to set spa_log_state to SPA_LOG_CLEAR earlier + * when we first figure out whether the current uberblock is + * checkpointed or not. Unfortunately, that would discard all + * the logs, including the ones that are claimed, and we would + * leak space. + */ + if (spa_get_log_state(zilog->zl_spa) == SPA_LOG_CLEAR || + (zilog->zl_spa->spa_uberblock.ub_checkpoint_txg != 0 && + zh->zh_claim_txg == 0)) { + if (!BP_IS_HOLE(&zh->zh_log)) { + (void) zil_parse(zilog, zil_clear_log_block, + zil_noop_log_record, tx, first_txg); + } + BP_ZERO(&zh->zh_log); + dsl_dataset_dirty(dmu_objset_ds(os), tx); + dmu_objset_disown(os, FTAG); + return (0); + } + + /* + * If we are not rewinding and opening the pool normally, then + * the min_claim_txg should be equal to the first txg of the pool. + */ + ASSERT3U(first_txg, ==, spa_first_txg(zilog->zl_spa)); + + /* + * Claim all log blocks if we haven't already done so, and remember + * the highest claimed sequence number. This ensures that if we can + * read only part of the log now (e.g. due to a missing device), + * but we can read the entire log later, we will not try to replay + * or destroy beyond the last block we successfully claimed. + */ + ASSERT3U(zh->zh_claim_txg, <=, first_txg); + if (zh->zh_claim_txg == 0 && !BP_IS_HOLE(&zh->zh_log)) { + (void) zil_parse(zilog, zil_claim_log_block, + zil_claim_log_record, tx, first_txg); + zh->zh_claim_txg = first_txg; + zh->zh_claim_blk_seq = zilog->zl_parse_blk_seq; + zh->zh_claim_lr_seq = zilog->zl_parse_lr_seq; + if (zilog->zl_parse_lr_count || zilog->zl_parse_blk_count > 1) + zh->zh_flags |= ZIL_REPLAY_NEEDED; + zh->zh_flags |= ZIL_CLAIM_LR_SEQ_VALID; + dsl_dataset_dirty(dmu_objset_ds(os), tx); + } + + ASSERT3U(first_txg, ==, (spa_last_synced_txg(zilog->zl_spa) + 1)); + dmu_objset_disown(os, FTAG); + return (0); +} + +/* + * Check the log by walking the log chain. + * Checksum errors are ok as they indicate the end of the chain. + * Any other error (no device or read failure) returns an error. + */ +/* ARGSUSED */ +int +zil_check_log_chain(dsl_pool_t *dp, dsl_dataset_t *ds, void *tx) +{ + zilog_t *zilog; + objset_t *os; + blkptr_t *bp; + int error; + + ASSERT(tx == NULL); + + error = dmu_objset_from_ds(ds, &os); + if (error != 0) { + cmn_err(CE_WARN, "can't open objset %llu, error %d", + (unsigned long long)ds->ds_object, error); + return (0); + } + + zilog = dmu_objset_zil(os); + bp = (blkptr_t *)&zilog->zl_header->zh_log; + + if (!BP_IS_HOLE(bp)) { + vdev_t *vd; + boolean_t valid = B_TRUE; + + /* + * Check the first block and determine if it's on a log device + * which may have been removed or faulted prior to loading this + * pool. If so, there's no point in checking the rest of the + * log as its content should have already been synced to the + * pool. + */ + spa_config_enter(os->os_spa, SCL_STATE, FTAG, RW_READER); + vd = vdev_lookup_top(os->os_spa, DVA_GET_VDEV(&bp->blk_dva[0])); + if (vd->vdev_islog && vdev_is_dead(vd)) + valid = vdev_log_state_valid(vd); + spa_config_exit(os->os_spa, SCL_STATE, FTAG); + + if (!valid) + return (0); + + /* + * Check whether the current uberblock is checkpointed (e.g. + * we are rewinding) and whether the current header has been + * claimed or not. If it hasn't then skip verifying it. We + * do this because its ZIL blocks may be part of the pool's + * state before the rewind, which is no longer valid. + */ + zil_header_t *zh = zil_header_in_syncing_context(zilog); + if (zilog->zl_spa->spa_uberblock.ub_checkpoint_txg != 0 && + zh->zh_claim_txg == 0) + return (0); + } + + /* + * Because tx == NULL, zil_claim_log_block() will not actually claim + * any blocks, but just determine whether it is possible to do so. + * In addition to checking the log chain, zil_claim_log_block() + * will invoke zio_claim() with a done func of spa_claim_notify(), + * which will update spa_max_claim_txg. See spa_load() for details. + */ + error = zil_parse(zilog, zil_claim_log_block, zil_claim_log_record, tx, + zilog->zl_header->zh_claim_txg ? -1ULL : + spa_min_claim_txg(os->os_spa)); + + return ((error == ECKSUM || error == ENOENT) ? 0 : error); +} + +/* + * When an itx is "skipped", this function is used to properly mark the + * waiter as "done, and signal any thread(s) waiting on it. An itx can + * be skipped (and not committed to an lwb) for a variety of reasons, + * one of them being that the itx was committed via spa_sync(), prior to + * it being committed to an lwb; this can happen if a thread calling + * zil_commit() is racing with spa_sync(). + */ +static void +zil_commit_waiter_skip(zil_commit_waiter_t *zcw) +{ + mutex_enter(&zcw->zcw_lock); + ASSERT3B(zcw->zcw_done, ==, B_FALSE); + zcw->zcw_done = B_TRUE; + cv_broadcast(&zcw->zcw_cv); + mutex_exit(&zcw->zcw_lock); +} + +/* + * This function is used when the given waiter is to be linked into an + * lwb's "lwb_waiter" list; i.e. when the itx is committed to the lwb. + * At this point, the waiter will no longer be referenced by the itx, + * and instead, will be referenced by the lwb. + */ +static void +zil_commit_waiter_link_lwb(zil_commit_waiter_t *zcw, lwb_t *lwb) +{ + /* + * The lwb_waiters field of the lwb is protected by the zilog's + * zl_lock, thus it must be held when calling this function. + */ + ASSERT(MUTEX_HELD(&lwb->lwb_zilog->zl_lock)); + + mutex_enter(&zcw->zcw_lock); + ASSERT(!list_link_active(&zcw->zcw_node)); + ASSERT3P(zcw->zcw_lwb, ==, NULL); + ASSERT3P(lwb, !=, NULL); + ASSERT(lwb->lwb_state == LWB_STATE_OPENED || + lwb->lwb_state == LWB_STATE_ISSUED); + + list_insert_tail(&lwb->lwb_waiters, zcw); + zcw->zcw_lwb = lwb; + mutex_exit(&zcw->zcw_lock); +} + +/* + * This function is used when zio_alloc_zil() fails to allocate a ZIL + * block, and the given waiter must be linked to the "nolwb waiters" + * list inside of zil_process_commit_list(). + */ +static void +zil_commit_waiter_link_nolwb(zil_commit_waiter_t *zcw, list_t *nolwb) +{ + mutex_enter(&zcw->zcw_lock); + ASSERT(!list_link_active(&zcw->zcw_node)); + ASSERT3P(zcw->zcw_lwb, ==, NULL); + list_insert_tail(nolwb, zcw); + mutex_exit(&zcw->zcw_lock); +} + +void +zil_lwb_add_block(lwb_t *lwb, const blkptr_t *bp) +{ + avl_tree_t *t = &lwb->lwb_vdev_tree; + avl_index_t where; + zil_vdev_node_t *zv, zvsearch; + int ndvas = BP_GET_NDVAS(bp); + int i; + + if (zfs_nocacheflush) + return; + + mutex_enter(&lwb->lwb_vdev_lock); + for (i = 0; i < ndvas; i++) { + zvsearch.zv_vdev = DVA_GET_VDEV(&bp->blk_dva[i]); + if (avl_find(t, &zvsearch, &where) == NULL) { + zv = kmem_alloc(sizeof (*zv), KM_SLEEP); + zv->zv_vdev = zvsearch.zv_vdev; + avl_insert(t, zv, where); + } + } + mutex_exit(&lwb->lwb_vdev_lock); +} + +void +zil_lwb_add_txg(lwb_t *lwb, uint64_t txg) +{ + lwb->lwb_max_txg = MAX(lwb->lwb_max_txg, txg); +} + +/* + * This function is a called after all VDEVs associated with a given lwb + * write have completed their DKIOCFLUSHWRITECACHE command; or as soon + * as the lwb write completes, if "zfs_nocacheflush" is set. + * + * The intention is for this function to be called as soon as the + * contents of an lwb are considered "stable" on disk, and will survive + * any sudden loss of power. At this point, any threads waiting for the + * lwb to reach this state are signalled, and the "waiter" structures + * are marked "done". + */ +static void +zil_lwb_flush_vdevs_done(zio_t *zio) +{ + lwb_t *lwb = zio->io_private; + zilog_t *zilog = lwb->lwb_zilog; + dmu_tx_t *tx = lwb->lwb_tx; + zil_commit_waiter_t *zcw; + + spa_config_exit(zilog->zl_spa, SCL_STATE, lwb); + + zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); + + mutex_enter(&zilog->zl_lock); + + /* + * Ensure the lwb buffer pointer is cleared before releasing the + * txg. If we have had an allocation failure and the txg is + * waiting to sync then we want zil_sync() to remove the lwb so + * that it's not picked up as the next new one in + * zil_process_commit_list(). zil_sync() will only remove the + * lwb if lwb_buf is null. + */ + lwb->lwb_buf = NULL; + lwb->lwb_tx = NULL; + + ASSERT3U(lwb->lwb_issued_timestamp, >, 0); + zilog->zl_last_lwb_latency = gethrtime() - lwb->lwb_issued_timestamp; + + lwb->lwb_root_zio = NULL; + lwb->lwb_state = LWB_STATE_DONE; + + if (zilog->zl_last_lwb_opened == lwb) { + /* + * Remember the highest committed log sequence number + * for ztest. We only update this value when all the log + * writes succeeded, because ztest wants to ASSERT that + * it got the whole log chain. + */ + zilog->zl_commit_lr_seq = zilog->zl_lr_seq; + } + + while ((zcw = list_head(&lwb->lwb_waiters)) != NULL) { + mutex_enter(&zcw->zcw_lock); + + ASSERT(list_link_active(&zcw->zcw_node)); + list_remove(&lwb->lwb_waiters, zcw); + + ASSERT3P(zcw->zcw_lwb, ==, lwb); + zcw->zcw_lwb = NULL; + + zcw->zcw_zio_error = zio->io_error; + + ASSERT3B(zcw->zcw_done, ==, B_FALSE); + zcw->zcw_done = B_TRUE; + cv_broadcast(&zcw->zcw_cv); + + mutex_exit(&zcw->zcw_lock); + } + + mutex_exit(&zilog->zl_lock); + + /* + * Now that we've written this log block, we have a stable pointer + * to the next block in the chain, so it's OK to let the txg in + * which we allocated the next block sync. + */ + dmu_tx_commit(tx); +} + +/* + * This is called when an lwb write completes. This means, this specific + * lwb was written to disk, and all dependent lwb have also been + * written to disk. + * + * At this point, a DKIOCFLUSHWRITECACHE command hasn't been issued to + * the VDEVs involved in writing out this specific lwb. The lwb will be + * "done" once zil_lwb_flush_vdevs_done() is called, which occurs in the + * zio completion callback for the lwb's root zio. + */ +static void +zil_lwb_write_done(zio_t *zio) +{ + lwb_t *lwb = zio->io_private; + spa_t *spa = zio->io_spa; + zilog_t *zilog = lwb->lwb_zilog; + avl_tree_t *t = &lwb->lwb_vdev_tree; + void *cookie = NULL; + zil_vdev_node_t *zv; + + ASSERT3S(spa_config_held(spa, SCL_STATE, RW_READER), !=, 0); + + ASSERT(BP_GET_COMPRESS(zio->io_bp) == ZIO_COMPRESS_OFF); + ASSERT(BP_GET_TYPE(zio->io_bp) == DMU_OT_INTENT_LOG); + ASSERT(BP_GET_LEVEL(zio->io_bp) == 0); + ASSERT(BP_GET_BYTEORDER(zio->io_bp) == ZFS_HOST_BYTEORDER); + ASSERT(!BP_IS_GANG(zio->io_bp)); + ASSERT(!BP_IS_HOLE(zio->io_bp)); + ASSERT(BP_GET_FILL(zio->io_bp) == 0); + + abd_put(zio->io_abd); + + ASSERT3S(lwb->lwb_state, ==, LWB_STATE_ISSUED); + + mutex_enter(&zilog->zl_lock); + lwb->lwb_write_zio = NULL; + mutex_exit(&zilog->zl_lock); + + if (avl_numnodes(t) == 0) + return; + + /* + * If there was an IO error, we're not going to call zio_flush() + * on these vdevs, so we simply empty the tree and free the + * nodes. We avoid calling zio_flush() since there isn't any + * good reason for doing so, after the lwb block failed to be + * written out. + */ + if (zio->io_error != 0) { + while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) + kmem_free(zv, sizeof (*zv)); + return; + } + + while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) { + vdev_t *vd = vdev_lookup_top(spa, zv->zv_vdev); + if (vd != NULL) + zio_flush(lwb->lwb_root_zio, vd); + kmem_free(zv, sizeof (*zv)); + } +} + +/* + * This function's purpose is to "open" an lwb such that it is ready to + * accept new itxs being committed to it. To do this, the lwb's zio + * structures are created, and linked to the lwb. This function is + * idempotent; if the passed in lwb has already been opened, this + * function is essentially a no-op. + */ +static void +zil_lwb_write_open(zilog_t *zilog, lwb_t *lwb) +{ + zbookmark_phys_t zb; + zio_priority_t prio; + + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + ASSERT3P(lwb, !=, NULL); + EQUIV(lwb->lwb_root_zio == NULL, lwb->lwb_state == LWB_STATE_CLOSED); + EQUIV(lwb->lwb_root_zio != NULL, lwb->lwb_state == LWB_STATE_OPENED); + + SET_BOOKMARK(&zb, lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_OBJSET], + ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, + lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_SEQ]); + + if (lwb->lwb_root_zio == NULL) { + abd_t *lwb_abd = abd_get_from_buf(lwb->lwb_buf, + BP_GET_LSIZE(&lwb->lwb_blk)); + + if (!lwb->lwb_slog || zilog->zl_cur_used <= zil_slog_bulk) + prio = ZIO_PRIORITY_SYNC_WRITE; + else + prio = ZIO_PRIORITY_ASYNC_WRITE; + + lwb->lwb_root_zio = zio_root(zilog->zl_spa, + zil_lwb_flush_vdevs_done, lwb, ZIO_FLAG_CANFAIL); + ASSERT3P(lwb->lwb_root_zio, !=, NULL); + + lwb->lwb_write_zio = zio_rewrite(lwb->lwb_root_zio, + zilog->zl_spa, 0, &lwb->lwb_blk, lwb_abd, + BP_GET_LSIZE(&lwb->lwb_blk), zil_lwb_write_done, lwb, + prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE, &zb); + ASSERT3P(lwb->lwb_write_zio, !=, NULL); + + lwb->lwb_state = LWB_STATE_OPENED; + + mutex_enter(&zilog->zl_lock); + + /* + * The zilog's "zl_last_lwb_opened" field is used to + * build the lwb/zio dependency chain, which is used to + * preserve the ordering of lwb completions that is + * required by the semantics of the ZIL. Each new lwb + * zio becomes a parent of the "previous" lwb zio, such + * that the new lwb's zio cannot complete until the + * "previous" lwb's zio completes. + * + * This is required by the semantics of zil_commit(); + * the commit waiters attached to the lwbs will be woken + * in the lwb zio's completion callback, so this zio + * dependency graph ensures the waiters are woken in the + * correct order (the same order the lwbs were created). + */ + lwb_t *last_lwb_opened = zilog->zl_last_lwb_opened; + if (last_lwb_opened != NULL && + last_lwb_opened->lwb_state != LWB_STATE_DONE) { + ASSERT(last_lwb_opened->lwb_state == LWB_STATE_OPENED || + last_lwb_opened->lwb_state == LWB_STATE_ISSUED); + ASSERT3P(last_lwb_opened->lwb_root_zio, !=, NULL); + zio_add_child(lwb->lwb_root_zio, + last_lwb_opened->lwb_root_zio); + } + zilog->zl_last_lwb_opened = lwb; + + mutex_exit(&zilog->zl_lock); + } + + ASSERT3P(lwb->lwb_root_zio, !=, NULL); + ASSERT3P(lwb->lwb_write_zio, !=, NULL); + ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); +} + +/* + * Define a limited set of intent log block sizes. + * + * These must be a multiple of 4KB. Note only the amount used (again + * aligned to 4KB) actually gets written. However, we can't always just + * allocate SPA_OLD_MAXBLOCKSIZE as the slog space could be exhausted. + */ +uint64_t zil_block_buckets[] = { + 4096, /* non TX_WRITE */ + 8192+4096, /* data base */ + 32*1024 + 4096, /* NFS writes */ + UINT64_MAX +}; + +/* + * Start a log block write and advance to the next log block. + * Calls are serialized. + */ +static lwb_t * +zil_lwb_write_issue(zilog_t *zilog, lwb_t *lwb) +{ + lwb_t *nlwb = NULL; + zil_chain_t *zilc; + spa_t *spa = zilog->zl_spa; + blkptr_t *bp; + dmu_tx_t *tx; + uint64_t txg; + uint64_t zil_blksz, wsz; + int i, error; + boolean_t slog; + + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + ASSERT3P(lwb->lwb_root_zio, !=, NULL); + ASSERT3P(lwb->lwb_write_zio, !=, NULL); + ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); + + if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { + zilc = (zil_chain_t *)lwb->lwb_buf; + bp = &zilc->zc_next_blk; + } else { + zilc = (zil_chain_t *)(lwb->lwb_buf + lwb->lwb_sz); + bp = &zilc->zc_next_blk; + } + + ASSERT(lwb->lwb_nused <= lwb->lwb_sz); + + /* + * Allocate the next block and save its address in this block + * before writing it in order to establish the log chain. + * Note that if the allocation of nlwb synced before we wrote + * the block that points at it (lwb), we'd leak it if we crashed. + * Therefore, we don't do dmu_tx_commit() until zil_lwb_write_done(). + * We dirty the dataset to ensure that zil_sync() will be called + * to clean up in the event of allocation failure or I/O failure. + */ + + tx = dmu_tx_create(zilog->zl_os); + + /* + * Since we are not going to create any new dirty data, and we + * can even help with clearing the existing dirty data, we + * should not be subject to the dirty data based delays. We + * use TXG_NOTHROTTLE to bypass the delay mechanism. + */ + VERIFY0(dmu_tx_assign(tx, TXG_WAIT | TXG_NOTHROTTLE)); + + dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); + txg = dmu_tx_get_txg(tx); + + lwb->lwb_tx = tx; + + /* + * Log blocks are pre-allocated. Here we select the size of the next + * block, based on size used in the last block. + * - first find the smallest bucket that will fit the block from a + * limited set of block sizes. This is because it's faster to write + * blocks allocated from the same metaslab as they are adjacent or + * close. + * - next find the maximum from the new suggested size and an array of + * previous sizes. This lessens a picket fence effect of wrongly + * guesssing the size if we have a stream of say 2k, 64k, 2k, 64k + * requests. + * + * Note we only write what is used, but we can't just allocate + * the maximum block size because we can exhaust the available + * pool log space. + */ + zil_blksz = zilog->zl_cur_used + sizeof (zil_chain_t); + for (i = 0; zil_blksz > zil_block_buckets[i]; i++) + continue; + zil_blksz = zil_block_buckets[i]; + if (zil_blksz == UINT64_MAX) + zil_blksz = SPA_OLD_MAXBLOCKSIZE; + zilog->zl_prev_blks[zilog->zl_prev_rotor] = zil_blksz; + for (i = 0; i < ZIL_PREV_BLKS; i++) + zil_blksz = MAX(zil_blksz, zilog->zl_prev_blks[i]); + zilog->zl_prev_rotor = (zilog->zl_prev_rotor + 1) & (ZIL_PREV_BLKS - 1); + + BP_ZERO(bp); + + /* pass the old blkptr in order to spread log blocks across devs */ + error = zio_alloc_zil(spa, zilog->zl_os->os_dsl_dataset->ds_object, + txg, bp, &lwb->lwb_blk, zil_blksz, &slog); + if (error == 0) { + ASSERT3U(bp->blk_birth, ==, txg); + bp->blk_cksum = lwb->lwb_blk.blk_cksum; + bp->blk_cksum.zc_word[ZIL_ZC_SEQ]++; + + /* + * Allocate a new log write block (lwb). + */ + nlwb = zil_alloc_lwb(zilog, bp, slog, txg); + } + + if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { + /* For Slim ZIL only write what is used. */ + wsz = P2ROUNDUP_TYPED(lwb->lwb_nused, ZIL_MIN_BLKSZ, uint64_t); + ASSERT3U(wsz, <=, lwb->lwb_sz); + zio_shrink(lwb->lwb_write_zio, wsz); + + } else { + wsz = lwb->lwb_sz; + } + + zilc->zc_pad = 0; + zilc->zc_nused = lwb->lwb_nused; + zilc->zc_eck.zec_cksum = lwb->lwb_blk.blk_cksum; + + /* + * clear unused data for security + */ + bzero(lwb->lwb_buf + lwb->lwb_nused, wsz - lwb->lwb_nused); + + spa_config_enter(zilog->zl_spa, SCL_STATE, lwb, RW_READER); + + zil_lwb_add_block(lwb, &lwb->lwb_blk); + lwb->lwb_issued_timestamp = gethrtime(); + lwb->lwb_state = LWB_STATE_ISSUED; + + zio_nowait(lwb->lwb_root_zio); + zio_nowait(lwb->lwb_write_zio); + + /* + * If there was an allocation failure then nlwb will be null which + * forces a txg_wait_synced(). + */ + return (nlwb); +} + +static lwb_t * +zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb) +{ + lr_t *lrcb, *lrc; + lr_write_t *lrwb, *lrw; + char *lr_buf; + uint64_t dlen, dnow, lwb_sp, reclen, txg; + + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + ASSERT3P(lwb, !=, NULL); + ASSERT3P(lwb->lwb_buf, !=, NULL); + + zil_lwb_write_open(zilog, lwb); + + lrc = &itx->itx_lr; + lrw = (lr_write_t *)lrc; + + /* + * A commit itx doesn't represent any on-disk state; instead + * it's simply used as a place holder on the commit list, and + * provides a mechanism for attaching a "commit waiter" onto the + * correct lwb (such that the waiter can be signalled upon + * completion of that lwb). Thus, we don't process this itx's + * log record if it's a commit itx (these itx's don't have log + * records), and instead link the itx's waiter onto the lwb's + * list of waiters. + * + * For more details, see the comment above zil_commit(). + */ + if (lrc->lrc_txtype == TX_COMMIT) { + mutex_enter(&zilog->zl_lock); + zil_commit_waiter_link_lwb(itx->itx_private, lwb); + itx->itx_private = NULL; + mutex_exit(&zilog->zl_lock); + return (lwb); + } + + if (lrc->lrc_txtype == TX_WRITE && itx->itx_wr_state == WR_NEED_COPY) { + dlen = P2ROUNDUP_TYPED( + lrw->lr_length, sizeof (uint64_t), uint64_t); + } else { + dlen = 0; + } + reclen = lrc->lrc_reclen; + zilog->zl_cur_used += (reclen + dlen); + txg = lrc->lrc_txg; + + ASSERT3U(zilog->zl_cur_used, <, UINT64_MAX - (reclen + dlen)); + +cont: + /* + * If this record won't fit in the current log block, start a new one. + * For WR_NEED_COPY optimize layout for minimal number of chunks. + */ + lwb_sp = lwb->lwb_sz - lwb->lwb_nused; + if (reclen > lwb_sp || (reclen + dlen > lwb_sp && + lwb_sp < ZIL_MAX_WASTE_SPACE && (dlen % ZIL_MAX_LOG_DATA == 0 || + lwb_sp < reclen + dlen % ZIL_MAX_LOG_DATA))) { + lwb = zil_lwb_write_issue(zilog, lwb); + if (lwb == NULL) + return (NULL); + zil_lwb_write_open(zilog, lwb); + ASSERT(LWB_EMPTY(lwb)); + lwb_sp = lwb->lwb_sz - lwb->lwb_nused; + ASSERT3U(reclen + MIN(dlen, sizeof (uint64_t)), <=, lwb_sp); + } + + dnow = MIN(dlen, lwb_sp - reclen); + lr_buf = lwb->lwb_buf + lwb->lwb_nused; + bcopy(lrc, lr_buf, reclen); + lrcb = (lr_t *)lr_buf; /* Like lrc, but inside lwb. */ + lrwb = (lr_write_t *)lrcb; /* Like lrw, but inside lwb. */ + + /* + * If it's a write, fetch the data or get its blkptr as appropriate. + */ + if (lrc->lrc_txtype == TX_WRITE) { + if (txg > spa_freeze_txg(zilog->zl_spa)) + txg_wait_synced(zilog->zl_dmu_pool, txg); + if (itx->itx_wr_state != WR_COPIED) { + char *dbuf; + int error; + + if (itx->itx_wr_state == WR_NEED_COPY) { + dbuf = lr_buf + reclen; + lrcb->lrc_reclen += dnow; + if (lrwb->lr_length > dnow) + lrwb->lr_length = dnow; + lrw->lr_offset += dnow; + lrw->lr_length -= dnow; + } else { + ASSERT(itx->itx_wr_state == WR_INDIRECT); + dbuf = NULL; + } + + /* + * We pass in the "lwb_write_zio" rather than + * "lwb_root_zio" so that the "lwb_write_zio" + * becomes the parent of any zio's created by + * the "zl_get_data" callback. The vdevs are + * flushed after the "lwb_write_zio" completes, + * so we want to make sure that completion + * callback waits for these additional zio's, + * such that the vdevs used by those zio's will + * be included in the lwb's vdev tree, and those + * vdevs will be properly flushed. If we passed + * in "lwb_root_zio" here, then these additional + * vdevs may not be flushed; e.g. if these zio's + * completed after "lwb_write_zio" completed. + */ + error = zilog->zl_get_data(itx->itx_private, + lrwb, dbuf, lwb, lwb->lwb_write_zio); + + if (error == EIO) { + txg_wait_synced(zilog->zl_dmu_pool, txg); + return (lwb); + } + if (error != 0) { + ASSERT(error == ENOENT || error == EEXIST || + error == EALREADY); + return (lwb); + } + } + } + + /* + * We're actually making an entry, so update lrc_seq to be the + * log record sequence number. Note that this is generally not + * equal to the itx sequence number because not all transactions + * are synchronous, and sometimes spa_sync() gets there first. + */ + lrcb->lrc_seq = ++zilog->zl_lr_seq; + lwb->lwb_nused += reclen + dnow; + + zil_lwb_add_txg(lwb, txg); + + ASSERT3U(lwb->lwb_nused, <=, lwb->lwb_sz); + ASSERT0(P2PHASE(lwb->lwb_nused, sizeof (uint64_t))); + + dlen -= dnow; + if (dlen > 0) { + zilog->zl_cur_used += reclen; + goto cont; + } + + return (lwb); +} + +itx_t * +zil_itx_create(uint64_t txtype, size_t lrsize) +{ + itx_t *itx; + + lrsize = P2ROUNDUP_TYPED(lrsize, sizeof (uint64_t), size_t); + + itx = kmem_alloc(offsetof(itx_t, itx_lr) + lrsize, KM_SLEEP); + itx->itx_lr.lrc_txtype = txtype; + itx->itx_lr.lrc_reclen = lrsize; + itx->itx_lr.lrc_seq = 0; /* defensive */ + itx->itx_sync = B_TRUE; /* default is synchronous */ + + return (itx); +} + +void +zil_itx_destroy(itx_t *itx) +{ + kmem_free(itx, offsetof(itx_t, itx_lr) + itx->itx_lr.lrc_reclen); +} + +/* + * Free up the sync and async itxs. The itxs_t has already been detached + * so no locks are needed. + */ +static void +zil_itxg_clean(itxs_t *itxs) +{ + itx_t *itx; + list_t *list; + avl_tree_t *t; + void *cookie; + itx_async_node_t *ian; + + list = &itxs->i_sync_list; + while ((itx = list_head(list)) != NULL) { + /* + * In the general case, commit itxs will not be found + * here, as they'll be committed to an lwb via + * zil_lwb_commit(), and free'd in that function. Having + * said that, it is still possible for commit itxs to be + * found here, due to the following race: + * + * - a thread calls zil_commit() which assigns the + * commit itx to a per-txg i_sync_list + * - zil_itxg_clean() is called (e.g. via spa_sync()) + * while the waiter is still on the i_sync_list + * + * There's nothing to prevent syncing the txg while the + * waiter is on the i_sync_list. This normally doesn't + * happen because spa_sync() is slower than zil_commit(), + * but if zil_commit() calls txg_wait_synced() (e.g. + * because zil_create() or zil_commit_writer_stall() is + * called) we will hit this case. + */ + if (itx->itx_lr.lrc_txtype == TX_COMMIT) + zil_commit_waiter_skip(itx->itx_private); + + list_remove(list, itx); + zil_itx_destroy(itx); + } + + cookie = NULL; + t = &itxs->i_async_tree; + while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) { + list = &ian->ia_list; + while ((itx = list_head(list)) != NULL) { + list_remove(list, itx); + /* commit itxs should never be on the async lists. */ + ASSERT3U(itx->itx_lr.lrc_txtype, !=, TX_COMMIT); + zil_itx_destroy(itx); + } + list_destroy(list); + kmem_free(ian, sizeof (itx_async_node_t)); + } + avl_destroy(t); + + kmem_free(itxs, sizeof (itxs_t)); +} + +static int +zil_aitx_compare(const void *x1, const void *x2) +{ + const uint64_t o1 = ((itx_async_node_t *)x1)->ia_foid; + const uint64_t o2 = ((itx_async_node_t *)x2)->ia_foid; + + return (AVL_CMP(o1, o2)); +} + +/* + * Remove all async itx with the given oid. + */ +static void +zil_remove_async(zilog_t *zilog, uint64_t oid) +{ + uint64_t otxg, txg; + itx_async_node_t *ian; + avl_tree_t *t; + avl_index_t where; + list_t clean_list; + itx_t *itx; + + ASSERT(oid != 0); + list_create(&clean_list, sizeof (itx_t), offsetof(itx_t, itx_node)); + + if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ + otxg = ZILTEST_TXG; + else + otxg = spa_last_synced_txg(zilog->zl_spa) + 1; + + for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { + itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; + + mutex_enter(&itxg->itxg_lock); + if (itxg->itxg_txg != txg) { + mutex_exit(&itxg->itxg_lock); + continue; + } + + /* + * Locate the object node and append its list. + */ + t = &itxg->itxg_itxs->i_async_tree; + ian = avl_find(t, &oid, &where); + if (ian != NULL) + list_move_tail(&clean_list, &ian->ia_list); + mutex_exit(&itxg->itxg_lock); + } + while ((itx = list_head(&clean_list)) != NULL) { + list_remove(&clean_list, itx); + /* commit itxs should never be on the async lists. */ + ASSERT3U(itx->itx_lr.lrc_txtype, !=, TX_COMMIT); + zil_itx_destroy(itx); + } + list_destroy(&clean_list); +} + +void +zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx) +{ + uint64_t txg; + itxg_t *itxg; + itxs_t *itxs, *clean = NULL; + + /* + * Object ids can be re-instantiated in the next txg so + * remove any async transactions to avoid future leaks. + * This can happen if a fsync occurs on the re-instantiated + * object for a WR_INDIRECT or WR_NEED_COPY write, which gets + * the new file data and flushes a write record for the old object. + */ + if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_REMOVE) + zil_remove_async(zilog, itx->itx_oid); + + /* + * Ensure the data of a renamed file is committed before the rename. + */ + if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_RENAME) + zil_async_to_sync(zilog, itx->itx_oid); + + if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) + txg = ZILTEST_TXG; + else + txg = dmu_tx_get_txg(tx); + + itxg = &zilog->zl_itxg[txg & TXG_MASK]; + mutex_enter(&itxg->itxg_lock); + itxs = itxg->itxg_itxs; + if (itxg->itxg_txg != txg) { + if (itxs != NULL) { + /* + * The zil_clean callback hasn't got around to cleaning + * this itxg. Save the itxs for release below. + * This should be rare. + */ + zfs_dbgmsg("zil_itx_assign: missed itx cleanup for " + "txg %llu", itxg->itxg_txg); + clean = itxg->itxg_itxs; + } + itxg->itxg_txg = txg; + itxs = itxg->itxg_itxs = kmem_zalloc(sizeof (itxs_t), KM_SLEEP); + + list_create(&itxs->i_sync_list, sizeof (itx_t), + offsetof(itx_t, itx_node)); + avl_create(&itxs->i_async_tree, zil_aitx_compare, + sizeof (itx_async_node_t), + offsetof(itx_async_node_t, ia_node)); + } + if (itx->itx_sync) { + list_insert_tail(&itxs->i_sync_list, itx); + } else { + avl_tree_t *t = &itxs->i_async_tree; + uint64_t foid = + LR_FOID_GET_OBJ(((lr_ooo_t *)&itx->itx_lr)->lr_foid); + itx_async_node_t *ian; + avl_index_t where; + + ian = avl_find(t, &foid, &where); + if (ian == NULL) { + ian = kmem_alloc(sizeof (itx_async_node_t), KM_SLEEP); + list_create(&ian->ia_list, sizeof (itx_t), + offsetof(itx_t, itx_node)); + ian->ia_foid = foid; + avl_insert(t, ian, where); + } + list_insert_tail(&ian->ia_list, itx); + } + + itx->itx_lr.lrc_txg = dmu_tx_get_txg(tx); + + /* + * We don't want to dirty the ZIL using ZILTEST_TXG, because + * zil_clean() will never be called using ZILTEST_TXG. Thus, we + * need to be careful to always dirty the ZIL using the "real" + * TXG (not itxg_txg) even when the SPA is frozen. + */ + zilog_dirty(zilog, dmu_tx_get_txg(tx)); + mutex_exit(&itxg->itxg_lock); + + /* Release the old itxs now we've dropped the lock */ + if (clean != NULL) + zil_itxg_clean(clean); +} + +/* + * If there are any in-memory intent log transactions which have now been + * synced then start up a taskq to free them. We should only do this after we + * have written out the uberblocks (i.e. txg has been comitted) so that + * don't inadvertently clean out in-memory log records that would be required + * by zil_commit(). + */ +void +zil_clean(zilog_t *zilog, uint64_t synced_txg) +{ + itxg_t *itxg = &zilog->zl_itxg[synced_txg & TXG_MASK]; + itxs_t *clean_me; + + ASSERT3U(synced_txg, <, ZILTEST_TXG); + + mutex_enter(&itxg->itxg_lock); + if (itxg->itxg_itxs == NULL || itxg->itxg_txg == ZILTEST_TXG) { + mutex_exit(&itxg->itxg_lock); + return; + } + ASSERT3U(itxg->itxg_txg, <=, synced_txg); + ASSERT3U(itxg->itxg_txg, !=, 0); + clean_me = itxg->itxg_itxs; + itxg->itxg_itxs = NULL; + itxg->itxg_txg = 0; + mutex_exit(&itxg->itxg_lock); + /* + * Preferably start a task queue to free up the old itxs but + * if taskq_dispatch can't allocate resources to do that then + * free it in-line. This should be rare. Note, using TQ_SLEEP + * created a bad performance problem. + */ + ASSERT3P(zilog->zl_dmu_pool, !=, NULL); + ASSERT3P(zilog->zl_dmu_pool->dp_zil_clean_taskq, !=, NULL); + if (taskq_dispatch(zilog->zl_dmu_pool->dp_zil_clean_taskq, + (void (*)(void *))zil_itxg_clean, clean_me, TQ_NOSLEEP) == 0) + zil_itxg_clean(clean_me); +} + +/* + * This function will traverse the queue of itxs that need to be + * committed, and move them onto the ZIL's zl_itx_commit_list. + */ +static void +zil_get_commit_list(zilog_t *zilog) +{ + uint64_t otxg, txg; + list_t *commit_list = &zilog->zl_itx_commit_list; + + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + + if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ + otxg = ZILTEST_TXG; + else + otxg = spa_last_synced_txg(zilog->zl_spa) + 1; + + /* + * This is inherently racy, since there is nothing to prevent + * the last synced txg from changing. That's okay since we'll + * only commit things in the future. + */ + for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { + itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; + + mutex_enter(&itxg->itxg_lock); + if (itxg->itxg_txg != txg) { + mutex_exit(&itxg->itxg_lock); + continue; + } + + /* + * If we're adding itx records to the zl_itx_commit_list, + * then the zil better be dirty in this "txg". We can assert + * that here since we're holding the itxg_lock which will + * prevent spa_sync from cleaning it. Once we add the itxs + * to the zl_itx_commit_list we must commit it to disk even + * if it's unnecessary (i.e. the txg was synced). + */ + ASSERT(zilog_is_dirty_in_txg(zilog, txg) || + spa_freeze_txg(zilog->zl_spa) != UINT64_MAX); + list_move_tail(commit_list, &itxg->itxg_itxs->i_sync_list); + + mutex_exit(&itxg->itxg_lock); + } +} + +/* + * Move the async itxs for a specified object to commit into sync lists. + */ +void +zil_async_to_sync(zilog_t *zilog, uint64_t foid) +{ + uint64_t otxg, txg; + itx_async_node_t *ian; + avl_tree_t *t; + avl_index_t where; + + if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ + otxg = ZILTEST_TXG; + else + otxg = spa_last_synced_txg(zilog->zl_spa) + 1; + + /* + * This is inherently racy, since there is nothing to prevent + * the last synced txg from changing. + */ + for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { + itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; + + mutex_enter(&itxg->itxg_lock); + if (itxg->itxg_txg != txg) { + mutex_exit(&itxg->itxg_lock); + continue; + } + + /* + * If a foid is specified then find that node and append its + * list. Otherwise walk the tree appending all the lists + * to the sync list. We add to the end rather than the + * beginning to ensure the create has happened. + */ + t = &itxg->itxg_itxs->i_async_tree; + if (foid != 0) { + ian = avl_find(t, &foid, &where); + if (ian != NULL) { + list_move_tail(&itxg->itxg_itxs->i_sync_list, + &ian->ia_list); + } + } else { + void *cookie = NULL; + + while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) { + list_move_tail(&itxg->itxg_itxs->i_sync_list, + &ian->ia_list); + list_destroy(&ian->ia_list); + kmem_free(ian, sizeof (itx_async_node_t)); + } + } + mutex_exit(&itxg->itxg_lock); + } +} + +/* + * This function will prune commit itxs that are at the head of the + * commit list (it won't prune past the first non-commit itx), and + * either: a) attach them to the last lwb that's still pending + * completion, or b) skip them altogether. + * + * This is used as a performance optimization to prevent commit itxs + * from generating new lwbs when it's unnecessary to do so. + */ +static void +zil_prune_commit_list(zilog_t *zilog) +{ + itx_t *itx; + + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + + while (itx = list_head(&zilog->zl_itx_commit_list)) { + lr_t *lrc = &itx->itx_lr; + if (lrc->lrc_txtype != TX_COMMIT) + break; + + mutex_enter(&zilog->zl_lock); + + lwb_t *last_lwb = zilog->zl_last_lwb_opened; + if (last_lwb == NULL || last_lwb->lwb_state == LWB_STATE_DONE) { + /* + * All of the itxs this waiter was waiting on + * must have already completed (or there were + * never any itx's for it to wait on), so it's + * safe to skip this waiter and mark it done. + */ + zil_commit_waiter_skip(itx->itx_private); + } else { + zil_commit_waiter_link_lwb(itx->itx_private, last_lwb); + itx->itx_private = NULL; + } + + mutex_exit(&zilog->zl_lock); + + list_remove(&zilog->zl_itx_commit_list, itx); + zil_itx_destroy(itx); + } + + IMPLY(itx != NULL, itx->itx_lr.lrc_txtype != TX_COMMIT); +} + +static void +zil_commit_writer_stall(zilog_t *zilog) +{ + /* + * When zio_alloc_zil() fails to allocate the next lwb block on + * disk, we must call txg_wait_synced() to ensure all of the + * lwbs in the zilog's zl_lwb_list are synced and then freed (in + * zil_sync()), such that any subsequent ZIL writer (i.e. a call + * to zil_process_commit_list()) will have to call zil_create(), + * and start a new ZIL chain. + * + * Since zil_alloc_zil() failed, the lwb that was previously + * issued does not have a pointer to the "next" lwb on disk. + * Thus, if another ZIL writer thread was to allocate the "next" + * on-disk lwb, that block could be leaked in the event of a + * crash (because the previous lwb on-disk would not point to + * it). + * + * We must hold the zilog's zl_issuer_lock while we do this, to + * ensure no new threads enter zil_process_commit_list() until + * all lwb's in the zl_lwb_list have been synced and freed + * (which is achieved via the txg_wait_synced() call). + */ + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + txg_wait_synced(zilog->zl_dmu_pool, 0); + ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL); +} + +/* + * This function will traverse the commit list, creating new lwbs as + * needed, and committing the itxs from the commit list to these newly + * created lwbs. Additionally, as a new lwb is created, the previous + * lwb will be issued to the zio layer to be written to disk. + */ +static void +zil_process_commit_list(zilog_t *zilog) +{ + spa_t *spa = zilog->zl_spa; + list_t nolwb_waiters; + lwb_t *lwb; + itx_t *itx; + + ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); + + /* + * Return if there's nothing to commit before we dirty the fs by + * calling zil_create(). + */ + if (list_head(&zilog->zl_itx_commit_list) == NULL) + return; + + list_create(&nolwb_waiters, sizeof (zil_commit_waiter_t), + offsetof(zil_commit_waiter_t, zcw_node)); + + lwb = list_tail(&zilog->zl_lwb_list); + if (lwb == NULL) { + lwb = zil_create(zilog); + } else { + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_DONE); + } + + while (itx = list_head(&zilog->zl_itx_commit_list)) { + lr_t *lrc = &itx->itx_lr; + uint64_t txg = lrc->lrc_txg; + + ASSERT3U(txg, !=, 0); + + if (lrc->lrc_txtype == TX_COMMIT) { + DTRACE_PROBE2(zil__process__commit__itx, + zilog_t *, zilog, itx_t *, itx); + } else { + DTRACE_PROBE2(zil__process__normal__itx, + zilog_t *, zilog, itx_t *, itx); + } + + boolean_t synced = txg <= spa_last_synced_txg(spa); + boolean_t frozen = txg > spa_freeze_txg(spa); + + /* + * If the txg of this itx has already been synced out, then + * we don't need to commit this itx to an lwb. This is + * because the data of this itx will have already been + * written to the main pool. This is inherently racy, and + * it's still ok to commit an itx whose txg has already + * been synced; this will result in a write that's + * unnecessary, but will do no harm. + * + * With that said, we always want to commit TX_COMMIT itxs + * to an lwb, regardless of whether or not that itx's txg + * has been synced out. We do this to ensure any OPENED lwb + * will always have at least one zil_commit_waiter_t linked + * to the lwb. + * + * As a counter-example, if we skipped TX_COMMIT itx's + * whose txg had already been synced, the following + * situation could occur if we happened to be racing with + * spa_sync: + * + * 1. we commit a non-TX_COMMIT itx to an lwb, where the + * itx's txg is 10 and the last synced txg is 9. + * 2. spa_sync finishes syncing out txg 10. + * 3. we move to the next itx in the list, it's a TX_COMMIT + * whose txg is 10, so we skip it rather than committing + * it to the lwb used in (1). + * + * If the itx that is skipped in (3) is the last TX_COMMIT + * itx in the commit list, than it's possible for the lwb + * used in (1) to remain in the OPENED state indefinitely. + * + * To prevent the above scenario from occuring, ensuring + * that once an lwb is OPENED it will transition to ISSUED + * and eventually DONE, we always commit TX_COMMIT itx's to + * an lwb here, even if that itx's txg has already been + * synced. + * + * Finally, if the pool is frozen, we _always_ commit the + * itx. The point of freezing the pool is to prevent data + * from being written to the main pool via spa_sync, and + * instead rely solely on the ZIL to persistently store the + * data; i.e. when the pool is frozen, the last synced txg + * value can't be trusted. + */ + if (frozen || !synced || lrc->lrc_txtype == TX_COMMIT) { + if (lwb != NULL) { + lwb = zil_lwb_commit(zilog, itx, lwb); + } else if (lrc->lrc_txtype == TX_COMMIT) { + ASSERT3P(lwb, ==, NULL); + zil_commit_waiter_link_nolwb( + itx->itx_private, &nolwb_waiters); + } + } + + list_remove(&zilog->zl_itx_commit_list, itx); + zil_itx_destroy(itx); + } + + if (lwb == NULL) { + /* + * This indicates zio_alloc_zil() failed to allocate the + * "next" lwb on-disk. When this happens, we must stall + * the ZIL write pipeline; see the comment within + * zil_commit_writer_stall() for more details. + */ + zil_commit_writer_stall(zilog); + + /* + * Additionally, we have to signal and mark the "nolwb" + * waiters as "done" here, since without an lwb, we + * can't do this via zil_lwb_flush_vdevs_done() like + * normal. + */ + zil_commit_waiter_t *zcw; + while (zcw = list_head(&nolwb_waiters)) { + zil_commit_waiter_skip(zcw); + list_remove(&nolwb_waiters, zcw); + } + } else { + ASSERT(list_is_empty(&nolwb_waiters)); + ASSERT3P(lwb, !=, NULL); + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_DONE); + + /* + * At this point, the ZIL block pointed at by the "lwb" + * variable is in one of the following states: "closed" + * or "open". + * + * If its "closed", then no itxs have been committed to + * it, so there's no point in issuing its zio (i.e. + * it's "empty"). + * + * If its "open" state, then it contains one or more + * itxs that eventually need to be committed to stable + * storage. In this case we intentionally do not issue + * the lwb's zio to disk yet, and instead rely on one of + * the following two mechanisms for issuing the zio: + * + * 1. Ideally, there will be more ZIL activity occuring + * on the system, such that this function will be + * immediately called again (not necessarily by the same + * thread) and this lwb's zio will be issued via + * zil_lwb_commit(). This way, the lwb is guaranteed to + * be "full" when it is issued to disk, and we'll make + * use of the lwb's size the best we can. + * + * 2. If there isn't sufficient ZIL activity occuring on + * the system, such that this lwb's zio isn't issued via + * zil_lwb_commit(), zil_commit_waiter() will issue the + * lwb's zio. If this occurs, the lwb is not guaranteed + * to be "full" by the time its zio is issued, and means + * the size of the lwb was "too large" given the amount + * of ZIL activity occuring on the system at that time. + * + * We do this for a couple of reasons: + * + * 1. To try and reduce the number of IOPs needed to + * write the same number of itxs. If an lwb has space + * available in it's buffer for more itxs, and more itxs + * will be committed relatively soon (relative to the + * latency of performing a write), then it's beneficial + * to wait for these "next" itxs. This way, more itxs + * can be committed to stable storage with fewer writes. + * + * 2. To try and use the largest lwb block size that the + * incoming rate of itxs can support. Again, this is to + * try and pack as many itxs into as few lwbs as + * possible, without significantly impacting the latency + * of each individual itx. + */ + } +} + +/* + * This function is responsible for ensuring the passed in commit waiter + * (and associated commit itx) is committed to an lwb. If the waiter is + * not already committed to an lwb, all itxs in the zilog's queue of + * itxs will be processed. The assumption is the passed in waiter's + * commit itx will found in the queue just like the other non-commit + * itxs, such that when the entire queue is processed, the waiter will + * have been commited to an lwb. + * + * The lwb associated with the passed in waiter is not guaranteed to + * have been issued by the time this function completes. If the lwb is + * not issued, we rely on future calls to zil_commit_writer() to issue + * the lwb, or the timeout mechanism found in zil_commit_waiter(). + */ +static void +zil_commit_writer(zilog_t *zilog, zil_commit_waiter_t *zcw) +{ + ASSERT(!MUTEX_HELD(&zilog->zl_lock)); + ASSERT(spa_writeable(zilog->zl_spa)); + + mutex_enter(&zilog->zl_issuer_lock); + + if (zcw->zcw_lwb != NULL || zcw->zcw_done) { + /* + * It's possible that, while we were waiting to acquire + * the "zl_issuer_lock", another thread committed this + * waiter to an lwb. If that occurs, we bail out early, + * without processing any of the zilog's queue of itxs. + * + * On certain workloads and system configurations, the + * "zl_issuer_lock" can become highly contended. In an + * attempt to reduce this contention, we immediately drop + * the lock if the waiter has already been processed. + * + * We've measured this optimization to reduce CPU spent + * contending on this lock by up to 5%, using a system + * with 32 CPUs, low latency storage (~50 usec writes), + * and 1024 threads performing sync writes. + */ + goto out; + } + + zil_get_commit_list(zilog); + zil_prune_commit_list(zilog); + zil_process_commit_list(zilog); + +out: + mutex_exit(&zilog->zl_issuer_lock); +} + +static void +zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw) +{ + ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); + ASSERT(MUTEX_HELD(&zcw->zcw_lock)); + ASSERT3B(zcw->zcw_done, ==, B_FALSE); + + lwb_t *lwb = zcw->zcw_lwb; + ASSERT3P(lwb, !=, NULL); + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_CLOSED); + + /* + * If the lwb has already been issued by another thread, we can + * immediately return since there's no work to be done (the + * point of this function is to issue the lwb). Additionally, we + * do this prior to acquiring the zl_issuer_lock, to avoid + * acquiring it when it's not necessary to do so. + */ + if (lwb->lwb_state == LWB_STATE_ISSUED || + lwb->lwb_state == LWB_STATE_DONE) + return; + + /* + * In order to call zil_lwb_write_issue() we must hold the + * zilog's "zl_issuer_lock". We can't simply acquire that lock, + * since we're already holding the commit waiter's "zcw_lock", + * and those two locks are aquired in the opposite order + * elsewhere. + */ + mutex_exit(&zcw->zcw_lock); + mutex_enter(&zilog->zl_issuer_lock); + mutex_enter(&zcw->zcw_lock); + + /* + * Since we just dropped and re-acquired the commit waiter's + * lock, we have to re-check to see if the waiter was marked + * "done" during that process. If the waiter was marked "done", + * the "lwb" pointer is no longer valid (it can be free'd after + * the waiter is marked "done"), so without this check we could + * wind up with a use-after-free error below. + */ + if (zcw->zcw_done) + goto out; + + ASSERT3P(lwb, ==, zcw->zcw_lwb); + + /* + * We've already checked this above, but since we hadn't acquired + * the zilog's zl_issuer_lock, we have to perform this check a + * second time while holding the lock. + * + * We don't need to hold the zl_lock since the lwb cannot transition + * from OPENED to ISSUED while we hold the zl_issuer_lock. The lwb + * _can_ transition from ISSUED to DONE, but it's OK to race with + * that transition since we treat the lwb the same, whether it's in + * the ISSUED or DONE states. + * + * The important thing, is we treat the lwb differently depending on + * if it's ISSUED or OPENED, and block any other threads that might + * attempt to issue this lwb. For that reason we hold the + * zl_issuer_lock when checking the lwb_state; we must not call + * zil_lwb_write_issue() if the lwb had already been issued. + * + * See the comment above the lwb_state_t structure definition for + * more details on the lwb states, and locking requirements. + */ + if (lwb->lwb_state == LWB_STATE_ISSUED || + lwb->lwb_state == LWB_STATE_DONE) + goto out; + + ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); + + /* + * As described in the comments above zil_commit_waiter() and + * zil_process_commit_list(), we need to issue this lwb's zio + * since we've reached the commit waiter's timeout and it still + * hasn't been issued. + */ + lwb_t *nlwb = zil_lwb_write_issue(zilog, lwb); + + IMPLY(nlwb != NULL, lwb->lwb_state != LWB_STATE_OPENED); + + /* + * Since the lwb's zio hadn't been issued by the time this thread + * reached its timeout, we reset the zilog's "zl_cur_used" field + * to influence the zil block size selection algorithm. + * + * By having to issue the lwb's zio here, it means the size of the + * lwb was too large, given the incoming throughput of itxs. By + * setting "zl_cur_used" to zero, we communicate this fact to the + * block size selection algorithm, so it can take this informaiton + * into account, and potentially select a smaller size for the + * next lwb block that is allocated. + */ + zilog->zl_cur_used = 0; + + if (nlwb == NULL) { + /* + * When zil_lwb_write_issue() returns NULL, this + * indicates zio_alloc_zil() failed to allocate the + * "next" lwb on-disk. When this occurs, the ZIL write + * pipeline must be stalled; see the comment within the + * zil_commit_writer_stall() function for more details. + * + * We must drop the commit waiter's lock prior to + * calling zil_commit_writer_stall() or else we can wind + * up with the following deadlock: + * + * - This thread is waiting for the txg to sync while + * holding the waiter's lock; txg_wait_synced() is + * used within txg_commit_writer_stall(). + * + * - The txg can't sync because it is waiting for this + * lwb's zio callback to call dmu_tx_commit(). + * + * - The lwb's zio callback can't call dmu_tx_commit() + * because it's blocked trying to acquire the waiter's + * lock, which occurs prior to calling dmu_tx_commit() + */ + mutex_exit(&zcw->zcw_lock); + zil_commit_writer_stall(zilog); + mutex_enter(&zcw->zcw_lock); + } + +out: + mutex_exit(&zilog->zl_issuer_lock); + ASSERT(MUTEX_HELD(&zcw->zcw_lock)); +} + +/* + * This function is responsible for performing the following two tasks: + * + * 1. its primary responsibility is to block until the given "commit + * waiter" is considered "done". + * + * 2. its secondary responsibility is to issue the zio for the lwb that + * the given "commit waiter" is waiting on, if this function has + * waited "long enough" and the lwb is still in the "open" state. + * + * Given a sufficient amount of itxs being generated and written using + * the ZIL, the lwb's zio will be issued via the zil_lwb_commit() + * function. If this does not occur, this secondary responsibility will + * ensure the lwb is issued even if there is not other synchronous + * activity on the system. + * + * For more details, see zil_process_commit_list(); more specifically, + * the comment at the bottom of that function. + */ +static void +zil_commit_waiter(zilog_t *zilog, zil_commit_waiter_t *zcw) +{ + ASSERT(!MUTEX_HELD(&zilog->zl_lock)); + ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); + ASSERT(spa_writeable(zilog->zl_spa)); + + mutex_enter(&zcw->zcw_lock); + + /* + * The timeout is scaled based on the lwb latency to avoid + * significantly impacting the latency of each individual itx. + * For more details, see the comment at the bottom of the + * zil_process_commit_list() function. + */ + int pct = MAX(zfs_commit_timeout_pct, 1); +#if defined(illumos) || !defined(_KERNEL) + hrtime_t sleep = (zilog->zl_last_lwb_latency * pct) / 100; + hrtime_t wakeup = gethrtime() + sleep; +#else + sbintime_t sleep = nstosbt((zilog->zl_last_lwb_latency * pct) / 100); + sbintime_t wakeup = getsbinuptime() + sleep; +#endif + boolean_t timedout = B_FALSE; + + while (!zcw->zcw_done) { + ASSERT(MUTEX_HELD(&zcw->zcw_lock)); + + lwb_t *lwb = zcw->zcw_lwb; + + /* + * Usually, the waiter will have a non-NULL lwb field here, + * but it's possible for it to be NULL as a result of + * zil_commit() racing with spa_sync(). + * + * When zil_clean() is called, it's possible for the itxg + * list (which may be cleaned via a taskq) to contain + * commit itxs. When this occurs, the commit waiters linked + * off of these commit itxs will not be committed to an + * lwb. Additionally, these commit waiters will not be + * marked done until zil_commit_waiter_skip() is called via + * zil_itxg_clean(). + * + * Thus, it's possible for this commit waiter (i.e. the + * "zcw" variable) to be found in this "in between" state; + * where it's "zcw_lwb" field is NULL, and it hasn't yet + * been skipped, so it's "zcw_done" field is still B_FALSE. + */ + IMPLY(lwb != NULL, lwb->lwb_state != LWB_STATE_CLOSED); + + if (lwb != NULL && lwb->lwb_state == LWB_STATE_OPENED) { + ASSERT3B(timedout, ==, B_FALSE); + + /* + * If the lwb hasn't been issued yet, then we + * need to wait with a timeout, in case this + * function needs to issue the lwb after the + * timeout is reached; responsibility (2) from + * the comment above this function. + */ +#if defined(illumos) || !defined(_KERNEL) + clock_t timeleft = cv_timedwait_hires(&zcw->zcw_cv, + &zcw->zcw_lock, wakeup, USEC2NSEC(1), + CALLOUT_FLAG_ABSOLUTE); + + if (timeleft >= 0 || zcw->zcw_done) + continue; +#else + int wait_err = cv_timedwait_sbt(&zcw->zcw_cv, + &zcw->zcw_lock, wakeup, SBT_1NS, C_ABSOLUTE); + if (wait_err != EWOULDBLOCK || zcw->zcw_done) + continue; +#endif + + timedout = B_TRUE; + zil_commit_waiter_timeout(zilog, zcw); + + if (!zcw->zcw_done) { + /* + * If the commit waiter has already been + * marked "done", it's possible for the + * waiter's lwb structure to have already + * been freed. Thus, we can only reliably + * make these assertions if the waiter + * isn't done. + */ + ASSERT3P(lwb, ==, zcw->zcw_lwb); + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_OPENED); + } + } else { + /* + * If the lwb isn't open, then it must have already + * been issued. In that case, there's no need to + * use a timeout when waiting for the lwb to + * complete. + * + * Additionally, if the lwb is NULL, the waiter + * will soon be signalled and marked done via + * zil_clean() and zil_itxg_clean(), so no timeout + * is required. + */ + + IMPLY(lwb != NULL, + lwb->lwb_state == LWB_STATE_ISSUED || + lwb->lwb_state == LWB_STATE_DONE); + cv_wait(&zcw->zcw_cv, &zcw->zcw_lock); + } + } + + mutex_exit(&zcw->zcw_lock); +} + +static zil_commit_waiter_t * +zil_alloc_commit_waiter() +{ + zil_commit_waiter_t *zcw = kmem_cache_alloc(zil_zcw_cache, KM_SLEEP); + + cv_init(&zcw->zcw_cv, NULL, CV_DEFAULT, NULL); + mutex_init(&zcw->zcw_lock, NULL, MUTEX_DEFAULT, NULL); + list_link_init(&zcw->zcw_node); + zcw->zcw_lwb = NULL; + zcw->zcw_done = B_FALSE; + zcw->zcw_zio_error = 0; + + return (zcw); +} + +static void +zil_free_commit_waiter(zil_commit_waiter_t *zcw) +{ + ASSERT(!list_link_active(&zcw->zcw_node)); + ASSERT3P(zcw->zcw_lwb, ==, NULL); + ASSERT3B(zcw->zcw_done, ==, B_TRUE); + mutex_destroy(&zcw->zcw_lock); + cv_destroy(&zcw->zcw_cv); + kmem_cache_free(zil_zcw_cache, zcw); +} + +/* + * This function is used to create a TX_COMMIT itx and assign it. This + * way, it will be linked into the ZIL's list of synchronous itxs, and + * then later committed to an lwb (or skipped) when + * zil_process_commit_list() is called. + */ +static void +zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) +{ + dmu_tx_t *tx = dmu_tx_create(zilog->zl_os); + VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); + + itx_t *itx = zil_itx_create(TX_COMMIT, sizeof (lr_t)); + itx->itx_sync = B_TRUE; + itx->itx_private = zcw; + + zil_itx_assign(zilog, itx, tx); + + dmu_tx_commit(tx); +} + +/* + * Commit ZFS Intent Log transactions (itxs) to stable storage. + * + * When writing ZIL transactions to the on-disk representation of the + * ZIL, the itxs are committed to a Log Write Block (lwb). Multiple + * itxs can be committed to a single lwb. Once a lwb is written and + * committed to stable storage (i.e. the lwb is written, and vdevs have + * been flushed), each itx that was committed to that lwb is also + * considered to be committed to stable storage. + * + * When an itx is committed to an lwb, the log record (lr_t) contained + * by the itx is copied into the lwb's zio buffer, and once this buffer + * is written to disk, it becomes an on-disk ZIL block. + * + * As itxs are generated, they're inserted into the ZIL's queue of + * uncommitted itxs. The semantics of zil_commit() are such that it will + * block until all itxs that were in the queue when it was called, are + * committed to stable storage. + * + * If "foid" is zero, this means all "synchronous" and "asynchronous" + * itxs, for all objects in the dataset, will be committed to stable + * storage prior to zil_commit() returning. If "foid" is non-zero, all + * "synchronous" itxs for all objects, but only "asynchronous" itxs + * that correspond to the foid passed in, will be committed to stable + * storage prior to zil_commit() returning. + * + * Generally speaking, when zil_commit() is called, the consumer doesn't + * actually care about _all_ of the uncommitted itxs. Instead, they're + * simply trying to waiting for a specific itx to be committed to disk, + * but the interface(s) for interacting with the ZIL don't allow such + * fine-grained communication. A better interface would allow a consumer + * to create and assign an itx, and then pass a reference to this itx to + * zil_commit(); such that zil_commit() would return as soon as that + * specific itx was committed to disk (instead of waiting for _all_ + * itxs to be committed). + * + * When a thread calls zil_commit() a special "commit itx" will be + * generated, along with a corresponding "waiter" for this commit itx. + * zil_commit() will wait on this waiter's CV, such that when the waiter + * is marked done, and signalled, zil_commit() will return. + * + * This commit itx is inserted into the queue of uncommitted itxs. This + * provides an easy mechanism for determining which itxs were in the + * queue prior to zil_commit() having been called, and which itxs were + * added after zil_commit() was called. + * + * The commit it is special; it doesn't have any on-disk representation. + * When a commit itx is "committed" to an lwb, the waiter associated + * with it is linked onto the lwb's list of waiters. Then, when that lwb + * completes, each waiter on the lwb's list is marked done and signalled + * -- allowing the thread waiting on the waiter to return from zil_commit(). + * + * It's important to point out a few critical factors that allow us + * to make use of the commit itxs, commit waiters, per-lwb lists of + * commit waiters, and zio completion callbacks like we're doing: + * + * 1. The list of waiters for each lwb is traversed, and each commit + * waiter is marked "done" and signalled, in the zio completion + * callback of the lwb's zio[*]. + * + * * Actually, the waiters are signalled in the zio completion + * callback of the root zio for the DKIOCFLUSHWRITECACHE commands + * that are sent to the vdevs upon completion of the lwb zio. + * + * 2. When the itxs are inserted into the ZIL's queue of uncommitted + * itxs, the order in which they are inserted is preserved[*]; as + * itxs are added to the queue, they are added to the tail of + * in-memory linked lists. + * + * When committing the itxs to lwbs (to be written to disk), they + * are committed in the same order in which the itxs were added to + * the uncommitted queue's linked list(s); i.e. the linked list of + * itxs to commit is traversed from head to tail, and each itx is + * committed to an lwb in that order. + * + * * To clarify: + * + * - the order of "sync" itxs is preserved w.r.t. other + * "sync" itxs, regardless of the corresponding objects. + * - the order of "async" itxs is preserved w.r.t. other + * "async" itxs corresponding to the same object. + * - the order of "async" itxs is *not* preserved w.r.t. other + * "async" itxs corresponding to different objects. + * - the order of "sync" itxs w.r.t. "async" itxs (or vice + * versa) is *not* preserved, even for itxs that correspond + * to the same object. + * + * For more details, see: zil_itx_assign(), zil_async_to_sync(), + * zil_get_commit_list(), and zil_process_commit_list(). + * + * 3. The lwbs represent a linked list of blocks on disk. Thus, any + * lwb cannot be considered committed to stable storage, until its + * "previous" lwb is also committed to stable storage. This fact, + * coupled with the fact described above, means that itxs are + * committed in (roughly) the order in which they were generated. + * This is essential because itxs are dependent on prior itxs. + * Thus, we *must not* deem an itx as being committed to stable + * storage, until *all* prior itxs have also been committed to + * stable storage. + * + * To enforce this ordering of lwb zio's, while still leveraging as + * much of the underlying storage performance as possible, we rely + * on two fundamental concepts: + * + * 1. The creation and issuance of lwb zio's is protected by + * the zilog's "zl_issuer_lock", which ensures only a single + * thread is creating and/or issuing lwb's at a time + * 2. The "previous" lwb is a child of the "current" lwb + * (leveraging the zio parent-child depenency graph) + * + * By relying on this parent-child zio relationship, we can have + * many lwb zio's concurrently issued to the underlying storage, + * but the order in which they complete will be the same order in + * which they were created. + */ +void +zil_commit(zilog_t *zilog, uint64_t foid) +{ + /* + * We should never attempt to call zil_commit on a snapshot for + * a couple of reasons: + * + * 1. A snapshot may never be modified, thus it cannot have any + * in-flight itxs that would have modified the dataset. + * + * 2. By design, when zil_commit() is called, a commit itx will + * be assigned to this zilog; as a result, the zilog will be + * dirtied. We must not dirty the zilog of a snapshot; there's + * checks in the code that enforce this invariant, and will + * cause a panic if it's not upheld. + */ + ASSERT3B(dmu_objset_is_snapshot(zilog->zl_os), ==, B_FALSE); + + if (zilog->zl_sync == ZFS_SYNC_DISABLED) + return; + + if (!spa_writeable(zilog->zl_spa)) { + /* + * If the SPA is not writable, there should never be any + * pending itxs waiting to be committed to disk. If that + * weren't true, we'd skip writing those itxs out, and + * would break the sematics of zil_commit(); thus, we're + * verifying that truth before we return to the caller. + */ + ASSERT(list_is_empty(&zilog->zl_lwb_list)); + ASSERT3P(zilog->zl_last_lwb_opened, ==, NULL); + for (int i = 0; i < TXG_SIZE; i++) + ASSERT3P(zilog->zl_itxg[i].itxg_itxs, ==, NULL); + return; + } + + /* + * If the ZIL is suspended, we don't want to dirty it by calling + * zil_commit_itx_assign() below, nor can we write out + * lwbs like would be done in zil_commit_write(). Thus, we + * simply rely on txg_wait_synced() to maintain the necessary + * semantics, and avoid calling those functions altogether. + */ + if (zilog->zl_suspend > 0) { + txg_wait_synced(zilog->zl_dmu_pool, 0); + return; + } + + zil_commit_impl(zilog, foid); +} + +void +zil_commit_impl(zilog_t *zilog, uint64_t foid) +{ + /* + * Move the "async" itxs for the specified foid to the "sync" + * queues, such that they will be later committed (or skipped) + * to an lwb when zil_process_commit_list() is called. + * + * Since these "async" itxs must be committed prior to this + * call to zil_commit returning, we must perform this operation + * before we call zil_commit_itx_assign(). + */ + zil_async_to_sync(zilog, foid); + + /* + * We allocate a new "waiter" structure which will initially be + * linked to the commit itx using the itx's "itx_private" field. + * Since the commit itx doesn't represent any on-disk state, + * when it's committed to an lwb, rather than copying the its + * lr_t into the lwb's buffer, the commit itx's "waiter" will be + * added to the lwb's list of waiters. Then, when the lwb is + * committed to stable storage, each waiter in the lwb's list of + * waiters will be marked "done", and signalled. + * + * We must create the waiter and assign the commit itx prior to + * calling zil_commit_writer(), or else our specific commit itx + * is not guaranteed to be committed to an lwb prior to calling + * zil_commit_waiter(). + */ + zil_commit_waiter_t *zcw = zil_alloc_commit_waiter(); + zil_commit_itx_assign(zilog, zcw); + + zil_commit_writer(zilog, zcw); + zil_commit_waiter(zilog, zcw); + + if (zcw->zcw_zio_error != 0) { + /* + * If there was an error writing out the ZIL blocks that + * this thread is waiting on, then we fallback to + * relying on spa_sync() to write out the data this + * thread is waiting on. Obviously this has performance + * implications, but the expectation is for this to be + * an exceptional case, and shouldn't occur often. + */ + DTRACE_PROBE2(zil__commit__io__error, + zilog_t *, zilog, zil_commit_waiter_t *, zcw); + txg_wait_synced(zilog->zl_dmu_pool, 0); + } + + zil_free_commit_waiter(zcw); +} + +/* + * Called in syncing context to free committed log blocks and update log header. + */ +void +zil_sync(zilog_t *zilog, dmu_tx_t *tx) +{ + zil_header_t *zh = zil_header_in_syncing_context(zilog); + uint64_t txg = dmu_tx_get_txg(tx); + spa_t *spa = zilog->zl_spa; + uint64_t *replayed_seq = &zilog->zl_replayed_seq[txg & TXG_MASK]; + lwb_t *lwb; + + /* + * We don't zero out zl_destroy_txg, so make sure we don't try + * to destroy it twice. + */ + if (spa_sync_pass(spa) != 1) + return; + + mutex_enter(&zilog->zl_lock); + + ASSERT(zilog->zl_stop_sync == 0); + + if (*replayed_seq != 0) { + ASSERT(zh->zh_replay_seq < *replayed_seq); + zh->zh_replay_seq = *replayed_seq; + *replayed_seq = 0; + } + + if (zilog->zl_destroy_txg == txg) { + blkptr_t blk = zh->zh_log; + + ASSERT(list_head(&zilog->zl_lwb_list) == NULL); + + bzero(zh, sizeof (zil_header_t)); + bzero(zilog->zl_replayed_seq, sizeof (zilog->zl_replayed_seq)); + + if (zilog->zl_keep_first) { + /* + * If this block was part of log chain that couldn't + * be claimed because a device was missing during + * zil_claim(), but that device later returns, + * then this block could erroneously appear valid. + * To guard against this, assign a new GUID to the new + * log chain so it doesn't matter what blk points to. + */ + zil_init_log_chain(zilog, &blk); + zh->zh_log = blk; + } + } + + while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) { + zh->zh_log = lwb->lwb_blk; + if (lwb->lwb_buf != NULL || lwb->lwb_max_txg > txg) + break; + list_remove(&zilog->zl_lwb_list, lwb); + zio_free(spa, txg, &lwb->lwb_blk); + zil_free_lwb(zilog, lwb); + + /* + * If we don't have anything left in the lwb list then + * we've had an allocation failure and we need to zero + * out the zil_header blkptr so that we don't end + * up freeing the same block twice. + */ + if (list_head(&zilog->zl_lwb_list) == NULL) + BP_ZERO(&zh->zh_log); + } + mutex_exit(&zilog->zl_lock); +} + +/* ARGSUSED */ +static int +zil_lwb_cons(void *vbuf, void *unused, int kmflag) +{ + lwb_t *lwb = vbuf; + list_create(&lwb->lwb_waiters, sizeof (zil_commit_waiter_t), + offsetof(zil_commit_waiter_t, zcw_node)); + avl_create(&lwb->lwb_vdev_tree, zil_lwb_vdev_compare, + sizeof (zil_vdev_node_t), offsetof(zil_vdev_node_t, zv_node)); + mutex_init(&lwb->lwb_vdev_lock, NULL, MUTEX_DEFAULT, NULL); + return (0); +} + +/* ARGSUSED */ +static void +zil_lwb_dest(void *vbuf, void *unused) +{ + lwb_t *lwb = vbuf; + mutex_destroy(&lwb->lwb_vdev_lock); + avl_destroy(&lwb->lwb_vdev_tree); + list_destroy(&lwb->lwb_waiters); +} + +void +zil_init(void) +{ + zil_lwb_cache = kmem_cache_create("zil_lwb_cache", + sizeof (lwb_t), 0, zil_lwb_cons, zil_lwb_dest, NULL, NULL, NULL, 0); + + zil_zcw_cache = kmem_cache_create("zil_zcw_cache", + sizeof (zil_commit_waiter_t), 0, NULL, NULL, NULL, NULL, NULL, 0); +} + +void +zil_fini(void) +{ + kmem_cache_destroy(zil_zcw_cache); + kmem_cache_destroy(zil_lwb_cache); +} + +void +zil_set_sync(zilog_t *zilog, uint64_t sync) +{ + zilog->zl_sync = sync; +} + +void +zil_set_logbias(zilog_t *zilog, uint64_t logbias) +{ + zilog->zl_logbias = logbias; +} + +zilog_t * +zil_alloc(objset_t *os, zil_header_t *zh_phys) +{ + zilog_t *zilog; + + zilog = kmem_zalloc(sizeof (zilog_t), KM_SLEEP); + + zilog->zl_header = zh_phys; + zilog->zl_os = os; + zilog->zl_spa = dmu_objset_spa(os); + zilog->zl_dmu_pool = dmu_objset_pool(os); + zilog->zl_destroy_txg = TXG_INITIAL - 1; + zilog->zl_logbias = dmu_objset_logbias(os); + zilog->zl_sync = dmu_objset_syncprop(os); + zilog->zl_dirty_max_txg = 0; + zilog->zl_last_lwb_opened = NULL; + zilog->zl_last_lwb_latency = 0; + + mutex_init(&zilog->zl_lock, NULL, MUTEX_DEFAULT, NULL); + mutex_init(&zilog->zl_issuer_lock, NULL, MUTEX_DEFAULT, NULL); + + for (int i = 0; i < TXG_SIZE; i++) { + mutex_init(&zilog->zl_itxg[i].itxg_lock, NULL, + MUTEX_DEFAULT, NULL); + } + + list_create(&zilog->zl_lwb_list, sizeof (lwb_t), + offsetof(lwb_t, lwb_node)); + + list_create(&zilog->zl_itx_commit_list, sizeof (itx_t), + offsetof(itx_t, itx_node)); + + cv_init(&zilog->zl_cv_suspend, NULL, CV_DEFAULT, NULL); + + return (zilog); +} + +void +zil_free(zilog_t *zilog) +{ + zilog->zl_stop_sync = 1; + + ASSERT0(zilog->zl_suspend); + ASSERT0(zilog->zl_suspending); + + ASSERT(list_is_empty(&zilog->zl_lwb_list)); + list_destroy(&zilog->zl_lwb_list); + + ASSERT(list_is_empty(&zilog->zl_itx_commit_list)); + list_destroy(&zilog->zl_itx_commit_list); + + for (int i = 0; i < TXG_SIZE; i++) { + /* + * It's possible for an itx to be generated that doesn't dirty + * a txg (e.g. ztest TX_TRUNCATE). So there's no zil_clean() + * callback to remove the entry. We remove those here. + * + * Also free up the ziltest itxs. + */ + if (zilog->zl_itxg[i].itxg_itxs) + zil_itxg_clean(zilog->zl_itxg[i].itxg_itxs); + mutex_destroy(&zilog->zl_itxg[i].itxg_lock); + } + + mutex_destroy(&zilog->zl_issuer_lock); + mutex_destroy(&zilog->zl_lock); + + cv_destroy(&zilog->zl_cv_suspend); + + kmem_free(zilog, sizeof (zilog_t)); +} + +/* + * Open an intent log. + */ +zilog_t * +zil_open(objset_t *os, zil_get_data_t *get_data) +{ + zilog_t *zilog = dmu_objset_zil(os); + + ASSERT3P(zilog->zl_get_data, ==, NULL); + ASSERT3P(zilog->zl_last_lwb_opened, ==, NULL); + ASSERT(list_is_empty(&zilog->zl_lwb_list)); + + zilog->zl_get_data = get_data; + + return (zilog); +} + +/* + * Close an intent log. + */ +void +zil_close(zilog_t *zilog) +{ + lwb_t *lwb; + uint64_t txg; + + if (!dmu_objset_is_snapshot(zilog->zl_os)) { + zil_commit(zilog, 0); + } else { + ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL); + ASSERT0(zilog->zl_dirty_max_txg); + ASSERT3B(zilog_is_dirty(zilog), ==, B_FALSE); + } + + mutex_enter(&zilog->zl_lock); + lwb = list_tail(&zilog->zl_lwb_list); + if (lwb == NULL) + txg = zilog->zl_dirty_max_txg; + else + txg = MAX(zilog->zl_dirty_max_txg, lwb->lwb_max_txg); + mutex_exit(&zilog->zl_lock); + + /* + * We need to use txg_wait_synced() to wait long enough for the + * ZIL to be clean, and to wait for all pending lwbs to be + * written out. + */ + if (txg) + txg_wait_synced(zilog->zl_dmu_pool, txg); + + if (txg < spa_freeze_txg(zilog->zl_spa)) + ASSERT(!zilog_is_dirty(zilog)); + + zilog->zl_get_data = NULL; + + /* + * We should have only one lwb left on the list; remove it now. + */ + mutex_enter(&zilog->zl_lock); + lwb = list_head(&zilog->zl_lwb_list); + if (lwb != NULL) { + ASSERT3P(lwb, ==, list_tail(&zilog->zl_lwb_list)); + ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); + list_remove(&zilog->zl_lwb_list, lwb); + zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); + zil_free_lwb(zilog, lwb); + } + mutex_exit(&zilog->zl_lock); +} + +static char *suspend_tag = "zil suspending"; + +/* + * Suspend an intent log. While in suspended mode, we still honor + * synchronous semantics, but we rely on txg_wait_synced() to do it. + * On old version pools, we suspend the log briefly when taking a + * snapshot so that it will have an empty intent log. + * + * Long holds are not really intended to be used the way we do here -- + * held for such a short time. A concurrent caller of dsl_dataset_long_held() + * could fail. Therefore we take pains to only put a long hold if it is + * actually necessary. Fortunately, it will only be necessary if the + * objset is currently mounted (or the ZVOL equivalent). In that case it + * will already have a long hold, so we are not really making things any worse. + * + * Ideally, we would locate the existing long-holder (i.e. the zfsvfs_t or + * zvol_state_t), and use their mechanism to prevent their hold from being + * dropped (e.g. VFS_HOLD()). However, that would be even more pain for + * very little gain. + * + * if cookiep == NULL, this does both the suspend & resume. + * Otherwise, it returns with the dataset "long held", and the cookie + * should be passed into zil_resume(). + */ +int +zil_suspend(const char *osname, void **cookiep) +{ + objset_t *os; + zilog_t *zilog; + const zil_header_t *zh; + int error; + + error = dmu_objset_hold(osname, suspend_tag, &os); + if (error != 0) + return (error); + zilog = dmu_objset_zil(os); + + mutex_enter(&zilog->zl_lock); + zh = zilog->zl_header; + + if (zh->zh_flags & ZIL_REPLAY_NEEDED) { /* unplayed log */ + mutex_exit(&zilog->zl_lock); + dmu_objset_rele(os, suspend_tag); + return (SET_ERROR(EBUSY)); + } + + /* + * Don't put a long hold in the cases where we can avoid it. This + * is when there is no cookie so we are doing a suspend & resume + * (i.e. called from zil_vdev_offline()), and there's nothing to do + * for the suspend because it's already suspended, or there's no ZIL. + */ + if (cookiep == NULL && !zilog->zl_suspending && + (zilog->zl_suspend > 0 || BP_IS_HOLE(&zh->zh_log))) { + mutex_exit(&zilog->zl_lock); + dmu_objset_rele(os, suspend_tag); + return (0); + } + + dsl_dataset_long_hold(dmu_objset_ds(os), suspend_tag); + dsl_pool_rele(dmu_objset_pool(os), suspend_tag); + + zilog->zl_suspend++; + + if (zilog->zl_suspend > 1) { + /* + * Someone else is already suspending it. + * Just wait for them to finish. + */ + + while (zilog->zl_suspending) + cv_wait(&zilog->zl_cv_suspend, &zilog->zl_lock); + mutex_exit(&zilog->zl_lock); + + if (cookiep == NULL) + zil_resume(os); + else + *cookiep = os; + return (0); + } + + /* + * If there is no pointer to an on-disk block, this ZIL must not + * be active (e.g. filesystem not mounted), so there's nothing + * to clean up. + */ + if (BP_IS_HOLE(&zh->zh_log)) { + ASSERT(cookiep != NULL); /* fast path already handled */ + + *cookiep = os; + mutex_exit(&zilog->zl_lock); + return (0); + } + + zilog->zl_suspending = B_TRUE; + mutex_exit(&zilog->zl_lock); + + /* + * We need to use zil_commit_impl to ensure we wait for all + * LWB_STATE_OPENED and LWB_STATE_ISSUED lwb's to be committed + * to disk before proceeding. If we used zil_commit instead, it + * would just call txg_wait_synced(), because zl_suspend is set. + * txg_wait_synced() doesn't wait for these lwb's to be + * LWB_STATE_DONE before returning. + */ + zil_commit_impl(zilog, 0); + + /* + * Now that we've ensured all lwb's are LWB_STATE_DONE, we use + * txg_wait_synced() to ensure the data from the zilog has + * migrated to the main pool before calling zil_destroy(). + */ + txg_wait_synced(zilog->zl_dmu_pool, 0); + + zil_destroy(zilog, B_FALSE); + + mutex_enter(&zilog->zl_lock); + zilog->zl_suspending = B_FALSE; + cv_broadcast(&zilog->zl_cv_suspend); + mutex_exit(&zilog->zl_lock); + + if (cookiep == NULL) + zil_resume(os); + else + *cookiep = os; + return (0); +} + +void +zil_resume(void *cookie) +{ + objset_t *os = cookie; + zilog_t *zilog = dmu_objset_zil(os); + + mutex_enter(&zilog->zl_lock); + ASSERT(zilog->zl_suspend != 0); + zilog->zl_suspend--; + mutex_exit(&zilog->zl_lock); + dsl_dataset_long_rele(dmu_objset_ds(os), suspend_tag); + dsl_dataset_rele(dmu_objset_ds(os), suspend_tag); +} + +typedef struct zil_replay_arg { + zil_replay_func_t **zr_replay; + void *zr_arg; + boolean_t zr_byteswap; + char *zr_lr; +} zil_replay_arg_t; + +static int +zil_replay_error(zilog_t *zilog, lr_t *lr, int error) +{ + char name[ZFS_MAX_DATASET_NAME_LEN]; + + zilog->zl_replaying_seq--; /* didn't actually replay this one */ + + dmu_objset_name(zilog->zl_os, name); + + cmn_err(CE_WARN, "ZFS replay transaction error %d, " + "dataset %s, seq 0x%llx, txtype %llu %s\n", error, name, + (u_longlong_t)lr->lrc_seq, + (u_longlong_t)(lr->lrc_txtype & ~TX_CI), + (lr->lrc_txtype & TX_CI) ? "CI" : ""); + + return (error); +} + +static int +zil_replay_log_record(zilog_t *zilog, lr_t *lr, void *zra, uint64_t claim_txg) +{ + zil_replay_arg_t *zr = zra; + const zil_header_t *zh = zilog->zl_header; + uint64_t reclen = lr->lrc_reclen; + uint64_t txtype = lr->lrc_txtype; + int error = 0; + + zilog->zl_replaying_seq = lr->lrc_seq; + + if (lr->lrc_seq <= zh->zh_replay_seq) /* already replayed */ + return (0); + + if (lr->lrc_txg < claim_txg) /* already committed */ + return (0); + + /* Strip case-insensitive bit, still present in log record */ + txtype &= ~TX_CI; + + if (txtype == 0 || txtype >= TX_MAX_TYPE) + return (zil_replay_error(zilog, lr, EINVAL)); + + /* + * If this record type can be logged out of order, the object + * (lr_foid) may no longer exist. That's legitimate, not an error. + */ + if (TX_OOO(txtype)) { + error = dmu_object_info(zilog->zl_os, + LR_FOID_GET_OBJ(((lr_ooo_t *)lr)->lr_foid), NULL); + if (error == ENOENT || error == EEXIST) + return (0); + } + + /* + * Make a copy of the data so we can revise and extend it. + */ + bcopy(lr, zr->zr_lr, reclen); + + /* + * If this is a TX_WRITE with a blkptr, suck in the data. + */ + if (txtype == TX_WRITE && reclen == sizeof (lr_write_t)) { + error = zil_read_log_data(zilog, (lr_write_t *)lr, + zr->zr_lr + reclen); + if (error != 0) + return (zil_replay_error(zilog, lr, error)); + } + + /* + * The log block containing this lr may have been byteswapped + * so that we can easily examine common fields like lrc_txtype. + * However, the log is a mix of different record types, and only the + * replay vectors know how to byteswap their records. Therefore, if + * the lr was byteswapped, undo it before invoking the replay vector. + */ + if (zr->zr_byteswap) + byteswap_uint64_array(zr->zr_lr, reclen); + + /* + * We must now do two things atomically: replay this log record, + * and update the log header sequence number to reflect the fact that + * we did so. At the end of each replay function the sequence number + * is updated if we are in replay mode. + */ + error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, zr->zr_byteswap); + if (error != 0) { + /* + * The DMU's dnode layer doesn't see removes until the txg + * commits, so a subsequent claim can spuriously fail with + * EEXIST. So if we receive any error we try syncing out + * any removes then retry the transaction. Note that we + * specify B_FALSE for byteswap now, so we don't do it twice. + */ + txg_wait_synced(spa_get_dsl(zilog->zl_spa), 0); + error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, B_FALSE); + if (error != 0) + return (zil_replay_error(zilog, lr, error)); + } + return (0); +} + +/* ARGSUSED */ +static int +zil_incr_blks(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg) +{ + zilog->zl_replay_blks++; + + return (0); +} + +/* + * If this dataset has a non-empty intent log, replay it and destroy it. + */ +void +zil_replay(objset_t *os, void *arg, zil_replay_func_t *replay_func[TX_MAX_TYPE]) +{ + zilog_t *zilog = dmu_objset_zil(os); + const zil_header_t *zh = zilog->zl_header; + zil_replay_arg_t zr; + + if ((zh->zh_flags & ZIL_REPLAY_NEEDED) == 0) { + zil_destroy(zilog, B_TRUE); + return; + } + + zr.zr_replay = replay_func; + zr.zr_arg = arg; + zr.zr_byteswap = BP_SHOULD_BYTESWAP(&zh->zh_log); + zr.zr_lr = kmem_alloc(2 * SPA_MAXBLOCKSIZE, KM_SLEEP); + + /* + * Wait for in-progress removes to sync before starting replay. + */ + txg_wait_synced(zilog->zl_dmu_pool, 0); + + zilog->zl_replay = B_TRUE; + zilog->zl_replay_time = ddi_get_lbolt(); + ASSERT(zilog->zl_replay_blks == 0); + (void) zil_parse(zilog, zil_incr_blks, zil_replay_log_record, &zr, + zh->zh_claim_txg); + kmem_free(zr.zr_lr, 2 * SPA_MAXBLOCKSIZE); + + zil_destroy(zilog, B_FALSE); + txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); + zilog->zl_replay = B_FALSE; +} + +boolean_t +zil_replaying(zilog_t *zilog, dmu_tx_t *tx) +{ + if (zilog->zl_sync == ZFS_SYNC_DISABLED) + return (B_TRUE); + + if (zilog->zl_replay) { + dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); + zilog->zl_replayed_seq[dmu_tx_get_txg(tx) & TXG_MASK] = + zilog->zl_replaying_seq; + return (B_TRUE); + } + + return (B_FALSE); +} + +/* ARGSUSED */ +int +zil_reset(const char *osname, void *arg) +{ + int error; + + error = zil_suspend(osname, NULL); + if (error != 0) + return (SET_ERROR(EEXIST)); + return (0); +} |