diff options
Diffstat (limited to 'module/zfs/dsl_scan.c')
| -rw-r--r-- | module/zfs/dsl_scan.c | 4426 |
1 files changed, 4426 insertions, 0 deletions
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c new file mode 100644 index 000000000000..712af664e90f --- /dev/null +++ b/module/zfs/dsl_scan.c @@ -0,0 +1,4426 @@ +/* + * 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) 2008, 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2011, 2018 by Delphix. All rights reserved. + * Copyright 2016 Gary Mills + * Copyright (c) 2017, 2019, Datto Inc. All rights reserved. + * Copyright 2019 Joyent, Inc. + */ + +#include <sys/dsl_scan.h> +#include <sys/dsl_pool.h> +#include <sys/dsl_dataset.h> +#include <sys/dsl_prop.h> +#include <sys/dsl_dir.h> +#include <sys/dsl_synctask.h> +#include <sys/dnode.h> +#include <sys/dmu_tx.h> +#include <sys/dmu_objset.h> +#include <sys/arc.h> +#include <sys/zap.h> +#include <sys/zio.h> +#include <sys/zfs_context.h> +#include <sys/fs/zfs.h> +#include <sys/zfs_znode.h> +#include <sys/spa_impl.h> +#include <sys/vdev_impl.h> +#include <sys/zil_impl.h> +#include <sys/zio_checksum.h> +#include <sys/ddt.h> +#include <sys/sa.h> +#include <sys/sa_impl.h> +#include <sys/zfeature.h> +#include <sys/abd.h> +#include <sys/range_tree.h> +#ifdef _KERNEL +#include <sys/zfs_vfsops.h> +#endif + +/* + * Grand theory statement on scan queue sorting + * + * Scanning is implemented by recursively traversing all indirection levels + * in an object and reading all blocks referenced from said objects. This + * results in us approximately traversing the object from lowest logical + * offset to the highest. For best performance, we would want the logical + * blocks to be physically contiguous. However, this is frequently not the + * case with pools given the allocation patterns of copy-on-write filesystems. + * So instead, we put the I/Os into a reordering queue and issue them in a + * way that will most benefit physical disks (LBA-order). + * + * Queue management: + * + * Ideally, we would want to scan all metadata and queue up all block I/O + * prior to starting to issue it, because that allows us to do an optimal + * sorting job. This can however consume large amounts of memory. Therefore + * we continuously monitor the size of the queues and constrain them to 5% + * (zfs_scan_mem_lim_fact) of physmem. If the queues grow larger than this + * limit, we clear out a few of the largest extents at the head of the queues + * to make room for more scanning. Hopefully, these extents will be fairly + * large and contiguous, allowing us to approach sequential I/O throughput + * even without a fully sorted tree. + * + * Metadata scanning takes place in dsl_scan_visit(), which is called from + * dsl_scan_sync() every spa_sync(). If we have either fully scanned all + * metadata on the pool, or we need to make room in memory because our + * queues are too large, dsl_scan_visit() is postponed and + * scan_io_queues_run() is called from dsl_scan_sync() instead. This implies + * that metadata scanning and queued I/O issuing are mutually exclusive. This + * allows us to provide maximum sequential I/O throughput for the majority of + * I/O's issued since sequential I/O performance is significantly negatively + * impacted if it is interleaved with random I/O. + * + * Implementation Notes + * + * One side effect of the queued scanning algorithm is that the scanning code + * needs to be notified whenever a block is freed. This is needed to allow + * the scanning code to remove these I/Os from the issuing queue. Additionally, + * we do not attempt to queue gang blocks to be issued sequentially since this + * is very hard to do and would have an extremely limited performance benefit. + * Instead, we simply issue gang I/Os as soon as we find them using the legacy + * algorithm. + * + * Backwards compatibility + * + * This new algorithm is backwards compatible with the legacy on-disk data + * structures (and therefore does not require a new feature flag). + * Periodically during scanning (see zfs_scan_checkpoint_intval), the scan + * will stop scanning metadata (in logical order) and wait for all outstanding + * sorted I/O to complete. Once this is done, we write out a checkpoint + * bookmark, indicating that we have scanned everything logically before it. + * If the pool is imported on a machine without the new sorting algorithm, + * the scan simply resumes from the last checkpoint using the legacy algorithm. + */ + +typedef int (scan_cb_t)(dsl_pool_t *, const blkptr_t *, + const zbookmark_phys_t *); + +static scan_cb_t dsl_scan_scrub_cb; + +static int scan_ds_queue_compare(const void *a, const void *b); +static int scan_prefetch_queue_compare(const void *a, const void *b); +static void scan_ds_queue_clear(dsl_scan_t *scn); +static void scan_ds_prefetch_queue_clear(dsl_scan_t *scn); +static boolean_t scan_ds_queue_contains(dsl_scan_t *scn, uint64_t dsobj, + uint64_t *txg); +static void scan_ds_queue_insert(dsl_scan_t *scn, uint64_t dsobj, uint64_t txg); +static void scan_ds_queue_remove(dsl_scan_t *scn, uint64_t dsobj); +static void scan_ds_queue_sync(dsl_scan_t *scn, dmu_tx_t *tx); +static uint64_t dsl_scan_count_leaves(vdev_t *vd); + +extern int zfs_vdev_async_write_active_min_dirty_percent; + +/* + * By default zfs will check to ensure it is not over the hard memory + * limit before each txg. If finer-grained control of this is needed + * this value can be set to 1 to enable checking before scanning each + * block. + */ +int zfs_scan_strict_mem_lim = B_FALSE; + +/* + * Maximum number of parallelly executed bytes per leaf vdev. We attempt + * to strike a balance here between keeping the vdev queues full of I/Os + * at all times and not overflowing the queues to cause long latency, + * which would cause long txg sync times. No matter what, we will not + * overload the drives with I/O, since that is protected by + * zfs_vdev_scrub_max_active. + */ +unsigned long zfs_scan_vdev_limit = 4 << 20; + +int zfs_scan_issue_strategy = 0; +int zfs_scan_legacy = B_FALSE; /* don't queue & sort zios, go direct */ +unsigned long zfs_scan_max_ext_gap = 2 << 20; /* in bytes */ + +/* + * fill_weight is non-tunable at runtime, so we copy it at module init from + * zfs_scan_fill_weight. Runtime adjustments to zfs_scan_fill_weight would + * break queue sorting. + */ +int zfs_scan_fill_weight = 3; +static uint64_t fill_weight; + +/* See dsl_scan_should_clear() for details on the memory limit tunables */ +uint64_t zfs_scan_mem_lim_min = 16 << 20; /* bytes */ +uint64_t zfs_scan_mem_lim_soft_max = 128 << 20; /* bytes */ +int zfs_scan_mem_lim_fact = 20; /* fraction of physmem */ +int zfs_scan_mem_lim_soft_fact = 20; /* fraction of mem lim above */ + +int zfs_scrub_min_time_ms = 1000; /* min millisecs to scrub per txg */ +int zfs_obsolete_min_time_ms = 500; /* min millisecs to obsolete per txg */ +int zfs_free_min_time_ms = 1000; /* min millisecs to free per txg */ +int zfs_resilver_min_time_ms = 3000; /* min millisecs to resilver per txg */ +int zfs_scan_checkpoint_intval = 7200; /* in seconds */ +int zfs_scan_suspend_progress = 0; /* set to prevent scans from progressing */ +int zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */ +int zfs_no_scrub_prefetch = B_FALSE; /* set to disable scrub prefetch */ +enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE; +/* max number of blocks to free in a single TXG */ +unsigned long zfs_async_block_max_blocks = ULONG_MAX; +/* max number of dedup blocks to free in a single TXG */ +unsigned long zfs_max_async_dedup_frees = 100000; + +int zfs_resilver_disable_defer = 0; /* set to disable resilver deferring */ + +/* + * We wait a few txgs after importing a pool to begin scanning so that + * the import / mounting code isn't held up by scrub / resilver IO. + * Unfortunately, it is a bit difficult to determine exactly how long + * this will take since userspace will trigger fs mounts asynchronously + * and the kernel will create zvol minors asynchronously. As a result, + * the value provided here is a bit arbitrary, but represents a + * reasonable estimate of how many txgs it will take to finish fully + * importing a pool + */ +#define SCAN_IMPORT_WAIT_TXGS 5 + +#define DSL_SCAN_IS_SCRUB_RESILVER(scn) \ + ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \ + (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER) + +/* + * Enable/disable the processing of the free_bpobj object. + */ +int zfs_free_bpobj_enabled = 1; + +/* the order has to match pool_scan_type */ +static scan_cb_t *scan_funcs[POOL_SCAN_FUNCS] = { + NULL, + dsl_scan_scrub_cb, /* POOL_SCAN_SCRUB */ + dsl_scan_scrub_cb, /* POOL_SCAN_RESILVER */ +}; + +/* In core node for the scn->scn_queue. Represents a dataset to be scanned */ +typedef struct { + uint64_t sds_dsobj; + uint64_t sds_txg; + avl_node_t sds_node; +} scan_ds_t; + +/* + * This controls what conditions are placed on dsl_scan_sync_state(): + * SYNC_OPTIONAL) write out scn_phys iff scn_bytes_pending == 0 + * SYNC_MANDATORY) write out scn_phys always. scn_bytes_pending must be 0. + * SYNC_CACHED) if scn_bytes_pending == 0, write out scn_phys. Otherwise + * write out the scn_phys_cached version. + * See dsl_scan_sync_state for details. + */ +typedef enum { + SYNC_OPTIONAL, + SYNC_MANDATORY, + SYNC_CACHED +} state_sync_type_t; + +/* + * This struct represents the minimum information needed to reconstruct a + * zio for sequential scanning. This is useful because many of these will + * accumulate in the sequential IO queues before being issued, so saving + * memory matters here. + */ +typedef struct scan_io { + /* fields from blkptr_t */ + uint64_t sio_blk_prop; + uint64_t sio_phys_birth; + uint64_t sio_birth; + zio_cksum_t sio_cksum; + uint32_t sio_nr_dvas; + + /* fields from zio_t */ + uint32_t sio_flags; + zbookmark_phys_t sio_zb; + + /* members for queue sorting */ + union { + avl_node_t sio_addr_node; /* link into issuing queue */ + list_node_t sio_list_node; /* link for issuing to disk */ + } sio_nodes; + + /* + * There may be up to SPA_DVAS_PER_BP DVAs here from the bp, + * depending on how many were in the original bp. Only the + * first DVA is really used for sorting and issuing purposes. + * The other DVAs (if provided) simply exist so that the zio + * layer can find additional copies to repair from in the + * event of an error. This array must go at the end of the + * struct to allow this for the variable number of elements. + */ + dva_t sio_dva[0]; +} scan_io_t; + +#define SIO_SET_OFFSET(sio, x) DVA_SET_OFFSET(&(sio)->sio_dva[0], x) +#define SIO_SET_ASIZE(sio, x) DVA_SET_ASIZE(&(sio)->sio_dva[0], x) +#define SIO_GET_OFFSET(sio) DVA_GET_OFFSET(&(sio)->sio_dva[0]) +#define SIO_GET_ASIZE(sio) DVA_GET_ASIZE(&(sio)->sio_dva[0]) +#define SIO_GET_END_OFFSET(sio) \ + (SIO_GET_OFFSET(sio) + SIO_GET_ASIZE(sio)) +#define SIO_GET_MUSED(sio) \ + (sizeof (scan_io_t) + ((sio)->sio_nr_dvas * sizeof (dva_t))) + +struct dsl_scan_io_queue { + dsl_scan_t *q_scn; /* associated dsl_scan_t */ + vdev_t *q_vd; /* top-level vdev that this queue represents */ + + /* trees used for sorting I/Os and extents of I/Os */ + range_tree_t *q_exts_by_addr; + zfs_btree_t q_exts_by_size; + avl_tree_t q_sios_by_addr; + uint64_t q_sio_memused; + + /* members for zio rate limiting */ + uint64_t q_maxinflight_bytes; + uint64_t q_inflight_bytes; + kcondvar_t q_zio_cv; /* used under vd->vdev_scan_io_queue_lock */ + + /* per txg statistics */ + uint64_t q_total_seg_size_this_txg; + uint64_t q_segs_this_txg; + uint64_t q_total_zio_size_this_txg; + uint64_t q_zios_this_txg; +}; + +/* private data for dsl_scan_prefetch_cb() */ +typedef struct scan_prefetch_ctx { + zfs_refcount_t spc_refcnt; /* refcount for memory management */ + dsl_scan_t *spc_scn; /* dsl_scan_t for the pool */ + boolean_t spc_root; /* is this prefetch for an objset? */ + uint8_t spc_indblkshift; /* dn_indblkshift of current dnode */ + uint16_t spc_datablkszsec; /* dn_idatablkszsec of current dnode */ +} scan_prefetch_ctx_t; + +/* private data for dsl_scan_prefetch() */ +typedef struct scan_prefetch_issue_ctx { + avl_node_t spic_avl_node; /* link into scn->scn_prefetch_queue */ + scan_prefetch_ctx_t *spic_spc; /* spc for the callback */ + blkptr_t spic_bp; /* bp to prefetch */ + zbookmark_phys_t spic_zb; /* bookmark to prefetch */ +} scan_prefetch_issue_ctx_t; + +static void scan_exec_io(dsl_pool_t *dp, const blkptr_t *bp, int zio_flags, + const zbookmark_phys_t *zb, dsl_scan_io_queue_t *queue); +static void scan_io_queue_insert_impl(dsl_scan_io_queue_t *queue, + scan_io_t *sio); + +static dsl_scan_io_queue_t *scan_io_queue_create(vdev_t *vd); +static void scan_io_queues_destroy(dsl_scan_t *scn); + +static kmem_cache_t *sio_cache[SPA_DVAS_PER_BP]; + +/* sio->sio_nr_dvas must be set so we know which cache to free from */ +static void +sio_free(scan_io_t *sio) +{ + ASSERT3U(sio->sio_nr_dvas, >, 0); + ASSERT3U(sio->sio_nr_dvas, <=, SPA_DVAS_PER_BP); + + kmem_cache_free(sio_cache[sio->sio_nr_dvas - 1], sio); +} + +/* It is up to the caller to set sio->sio_nr_dvas for freeing */ +static scan_io_t * +sio_alloc(unsigned short nr_dvas) +{ + ASSERT3U(nr_dvas, >, 0); + ASSERT3U(nr_dvas, <=, SPA_DVAS_PER_BP); + + return (kmem_cache_alloc(sio_cache[nr_dvas - 1], KM_SLEEP)); +} + +void +scan_init(void) +{ + /* + * This is used in ext_size_compare() to weight segments + * based on how sparse they are. This cannot be changed + * mid-scan and the tree comparison functions don't currently + * have a mechanism for passing additional context to the + * compare functions. Thus we store this value globally and + * we only allow it to be set at module initialization time + */ + fill_weight = zfs_scan_fill_weight; + + for (int i = 0; i < SPA_DVAS_PER_BP; i++) { + char name[36]; + + (void) snprintf(name, sizeof (name), "sio_cache_%d", i); + sio_cache[i] = kmem_cache_create(name, + (sizeof (scan_io_t) + ((i + 1) * sizeof (dva_t))), + 0, NULL, NULL, NULL, NULL, NULL, 0); + } +} + +void +scan_fini(void) +{ + for (int i = 0; i < SPA_DVAS_PER_BP; i++) { + kmem_cache_destroy(sio_cache[i]); + } +} + +static inline boolean_t +dsl_scan_is_running(const dsl_scan_t *scn) +{ + return (scn->scn_phys.scn_state == DSS_SCANNING); +} + +boolean_t +dsl_scan_resilvering(dsl_pool_t *dp) +{ + return (dsl_scan_is_running(dp->dp_scan) && + dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER); +} + +static inline void +sio2bp(const scan_io_t *sio, blkptr_t *bp) +{ + bzero(bp, sizeof (*bp)); + bp->blk_prop = sio->sio_blk_prop; + bp->blk_phys_birth = sio->sio_phys_birth; + bp->blk_birth = sio->sio_birth; + bp->blk_fill = 1; /* we always only work with data pointers */ + bp->blk_cksum = sio->sio_cksum; + + ASSERT3U(sio->sio_nr_dvas, >, 0); + ASSERT3U(sio->sio_nr_dvas, <=, SPA_DVAS_PER_BP); + + bcopy(sio->sio_dva, bp->blk_dva, sio->sio_nr_dvas * sizeof (dva_t)); +} + +static inline void +bp2sio(const blkptr_t *bp, scan_io_t *sio, int dva_i) +{ + sio->sio_blk_prop = bp->blk_prop; + sio->sio_phys_birth = bp->blk_phys_birth; + sio->sio_birth = bp->blk_birth; + sio->sio_cksum = bp->blk_cksum; + sio->sio_nr_dvas = BP_GET_NDVAS(bp); + + /* + * Copy the DVAs to the sio. We need all copies of the block so + * that the self healing code can use the alternate copies if the + * first is corrupted. We want the DVA at index dva_i to be first + * in the sio since this is the primary one that we want to issue. + */ + for (int i = 0, j = dva_i; i < sio->sio_nr_dvas; i++, j++) { + sio->sio_dva[i] = bp->blk_dva[j % sio->sio_nr_dvas]; + } +} + +int +dsl_scan_init(dsl_pool_t *dp, uint64_t txg) +{ + int err; + dsl_scan_t *scn; + spa_t *spa = dp->dp_spa; + uint64_t f; + + scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP); + scn->scn_dp = dp; + + /* + * It's possible that we're resuming a scan after a reboot so + * make sure that the scan_async_destroying flag is initialized + * appropriately. + */ + ASSERT(!scn->scn_async_destroying); + scn->scn_async_destroying = spa_feature_is_active(dp->dp_spa, + SPA_FEATURE_ASYNC_DESTROY); + + /* + * Calculate the max number of in-flight bytes for pool-wide + * scanning operations (minimum 1MB). Limits for the issuing + * phase are done per top-level vdev and are handled separately. + */ + scn->scn_maxinflight_bytes = MAX(zfs_scan_vdev_limit * + dsl_scan_count_leaves(spa->spa_root_vdev), 1ULL << 20); + + avl_create(&scn->scn_queue, scan_ds_queue_compare, sizeof (scan_ds_t), + offsetof(scan_ds_t, sds_node)); + avl_create(&scn->scn_prefetch_queue, scan_prefetch_queue_compare, + sizeof (scan_prefetch_issue_ctx_t), + offsetof(scan_prefetch_issue_ctx_t, spic_avl_node)); + + err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT, + "scrub_func", sizeof (uint64_t), 1, &f); + if (err == 0) { + /* + * There was an old-style scrub in progress. Restart a + * new-style scrub from the beginning. + */ + scn->scn_restart_txg = txg; + zfs_dbgmsg("old-style scrub was in progress; " + "restarting new-style scrub in txg %llu", + (longlong_t)scn->scn_restart_txg); + + /* + * Load the queue obj from the old location so that it + * can be freed by dsl_scan_done(). + */ + (void) zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT, + "scrub_queue", sizeof (uint64_t), 1, + &scn->scn_phys.scn_queue_obj); + } else { + err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT, + DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS, + &scn->scn_phys); + /* + * Detect if the pool contains the signature of #2094. If it + * does properly update the scn->scn_phys structure and notify + * the administrator by setting an errata for the pool. + */ + if (err == EOVERFLOW) { + uint64_t zaptmp[SCAN_PHYS_NUMINTS + 1]; + VERIFY3S(SCAN_PHYS_NUMINTS, ==, 24); + VERIFY3S(offsetof(dsl_scan_phys_t, scn_flags), ==, + (23 * sizeof (uint64_t))); + + err = zap_lookup(dp->dp_meta_objset, + DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SCAN, + sizeof (uint64_t), SCAN_PHYS_NUMINTS + 1, &zaptmp); + if (err == 0) { + uint64_t overflow = zaptmp[SCAN_PHYS_NUMINTS]; + + if (overflow & ~DSL_SCAN_FLAGS_MASK || + scn->scn_async_destroying) { + spa->spa_errata = + ZPOOL_ERRATA_ZOL_2094_ASYNC_DESTROY; + return (EOVERFLOW); + } + + bcopy(zaptmp, &scn->scn_phys, + SCAN_PHYS_NUMINTS * sizeof (uint64_t)); + scn->scn_phys.scn_flags = overflow; + + /* Required scrub already in progress. */ + if (scn->scn_phys.scn_state == DSS_FINISHED || + scn->scn_phys.scn_state == DSS_CANCELED) + spa->spa_errata = + ZPOOL_ERRATA_ZOL_2094_SCRUB; + } + } + + if (err == ENOENT) + return (0); + else if (err) + return (err); + + /* + * We might be restarting after a reboot, so jump the issued + * counter to how far we've scanned. We know we're consistent + * up to here. + */ + scn->scn_issued_before_pass = scn->scn_phys.scn_examined; + + if (dsl_scan_is_running(scn) && + spa_prev_software_version(dp->dp_spa) < SPA_VERSION_SCAN) { + /* + * A new-type scrub was in progress on an old + * pool, and the pool was accessed by old + * software. Restart from the beginning, since + * the old software may have changed the pool in + * the meantime. + */ + scn->scn_restart_txg = txg; + zfs_dbgmsg("new-style scrub was modified " + "by old software; restarting in txg %llu", + (longlong_t)scn->scn_restart_txg); + } else if (dsl_scan_resilvering(dp)) { + /* + * If a resilver is in progress and there are already + * errors, restart it instead of finishing this scan and + * then restarting it. If there haven't been any errors + * then remember that the incore DTL is valid. + */ + if (scn->scn_phys.scn_errors > 0) { + scn->scn_restart_txg = txg; + zfs_dbgmsg("resilver can't excise DTL_MISSING " + "when finished; restarting in txg %llu", + (u_longlong_t)scn->scn_restart_txg); + } else { + /* it's safe to excise DTL when finished */ + spa->spa_scrub_started = B_TRUE; + } + } + } + + bcopy(&scn->scn_phys, &scn->scn_phys_cached, sizeof (scn->scn_phys)); + + /* reload the queue into the in-core state */ + if (scn->scn_phys.scn_queue_obj != 0) { + zap_cursor_t zc; + zap_attribute_t za; + + for (zap_cursor_init(&zc, dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj); + zap_cursor_retrieve(&zc, &za) == 0; + (void) zap_cursor_advance(&zc)) { + scan_ds_queue_insert(scn, + zfs_strtonum(za.za_name, NULL), + za.za_first_integer); + } + zap_cursor_fini(&zc); + } + + spa_scan_stat_init(spa); + return (0); +} + +void +dsl_scan_fini(dsl_pool_t *dp) +{ + if (dp->dp_scan != NULL) { + dsl_scan_t *scn = dp->dp_scan; + + if (scn->scn_taskq != NULL) + taskq_destroy(scn->scn_taskq); + + scan_ds_queue_clear(scn); + avl_destroy(&scn->scn_queue); + scan_ds_prefetch_queue_clear(scn); + avl_destroy(&scn->scn_prefetch_queue); + + kmem_free(dp->dp_scan, sizeof (dsl_scan_t)); + dp->dp_scan = NULL; + } +} + +static boolean_t +dsl_scan_restarting(dsl_scan_t *scn, dmu_tx_t *tx) +{ + return (scn->scn_restart_txg != 0 && + scn->scn_restart_txg <= tx->tx_txg); +} + +boolean_t +dsl_scan_resilver_scheduled(dsl_pool_t *dp) +{ + return ((dp->dp_scan && dp->dp_scan->scn_restart_txg != 0) || + (spa_async_tasks(dp->dp_spa) & SPA_ASYNC_RESILVER)); +} + +boolean_t +dsl_scan_scrubbing(const dsl_pool_t *dp) +{ + dsl_scan_phys_t *scn_phys = &dp->dp_scan->scn_phys; + + return (scn_phys->scn_state == DSS_SCANNING && + scn_phys->scn_func == POOL_SCAN_SCRUB); +} + +boolean_t +dsl_scan_is_paused_scrub(const dsl_scan_t *scn) +{ + return (dsl_scan_scrubbing(scn->scn_dp) && + scn->scn_phys.scn_flags & DSF_SCRUB_PAUSED); +} + +/* + * Writes out a persistent dsl_scan_phys_t record to the pool directory. + * Because we can be running in the block sorting algorithm, we do not always + * want to write out the record, only when it is "safe" to do so. This safety + * condition is achieved by making sure that the sorting queues are empty + * (scn_bytes_pending == 0). When this condition is not true, the sync'd state + * is inconsistent with how much actual scanning progress has been made. The + * kind of sync to be performed is specified by the sync_type argument. If the + * sync is optional, we only sync if the queues are empty. If the sync is + * mandatory, we do a hard ASSERT to make sure that the queues are empty. The + * third possible state is a "cached" sync. This is done in response to: + * 1) The dataset that was in the last sync'd dsl_scan_phys_t having been + * destroyed, so we wouldn't be able to restart scanning from it. + * 2) The snapshot that was in the last sync'd dsl_scan_phys_t having been + * superseded by a newer snapshot. + * 3) The dataset that was in the last sync'd dsl_scan_phys_t having been + * swapped with its clone. + * In all cases, a cached sync simply rewrites the last record we've written, + * just slightly modified. For the modifications that are performed to the + * last written dsl_scan_phys_t, see dsl_scan_ds_destroyed, + * dsl_scan_ds_snapshotted and dsl_scan_ds_clone_swapped. + */ +static void +dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx, state_sync_type_t sync_type) +{ + int i; + spa_t *spa = scn->scn_dp->dp_spa; + + ASSERT(sync_type != SYNC_MANDATORY || scn->scn_bytes_pending == 0); + if (scn->scn_bytes_pending == 0) { + for (i = 0; i < spa->spa_root_vdev->vdev_children; i++) { + vdev_t *vd = spa->spa_root_vdev->vdev_child[i]; + dsl_scan_io_queue_t *q = vd->vdev_scan_io_queue; + + if (q == NULL) + continue; + + mutex_enter(&vd->vdev_scan_io_queue_lock); + ASSERT3P(avl_first(&q->q_sios_by_addr), ==, NULL); + ASSERT3P(zfs_btree_first(&q->q_exts_by_size, NULL), ==, + NULL); + ASSERT3P(range_tree_first(q->q_exts_by_addr), ==, NULL); + mutex_exit(&vd->vdev_scan_io_queue_lock); + } + + if (scn->scn_phys.scn_queue_obj != 0) + scan_ds_queue_sync(scn, tx); + VERIFY0(zap_update(scn->scn_dp->dp_meta_objset, + DMU_POOL_DIRECTORY_OBJECT, + DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS, + &scn->scn_phys, tx)); + bcopy(&scn->scn_phys, &scn->scn_phys_cached, + sizeof (scn->scn_phys)); + + if (scn->scn_checkpointing) + zfs_dbgmsg("finish scan checkpoint"); + + scn->scn_checkpointing = B_FALSE; + scn->scn_last_checkpoint = ddi_get_lbolt(); + } else if (sync_type == SYNC_CACHED) { + VERIFY0(zap_update(scn->scn_dp->dp_meta_objset, + DMU_POOL_DIRECTORY_OBJECT, + DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS, + &scn->scn_phys_cached, tx)); + } +} + +/* ARGSUSED */ +static int +dsl_scan_setup_check(void *arg, dmu_tx_t *tx) +{ + dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan; + vdev_t *rvd = scn->scn_dp->dp_spa->spa_root_vdev; + + if (dsl_scan_is_running(scn) || vdev_rebuild_active(rvd)) + return (SET_ERROR(EBUSY)); + + return (0); +} + +static void +dsl_scan_setup_sync(void *arg, dmu_tx_t *tx) +{ + dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan; + pool_scan_func_t *funcp = arg; + dmu_object_type_t ot = 0; + dsl_pool_t *dp = scn->scn_dp; + spa_t *spa = dp->dp_spa; + + ASSERT(!dsl_scan_is_running(scn)); + ASSERT(*funcp > POOL_SCAN_NONE && *funcp < POOL_SCAN_FUNCS); + bzero(&scn->scn_phys, sizeof (scn->scn_phys)); + scn->scn_phys.scn_func = *funcp; + scn->scn_phys.scn_state = DSS_SCANNING; + scn->scn_phys.scn_min_txg = 0; + scn->scn_phys.scn_max_txg = tx->tx_txg; + scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */ + scn->scn_phys.scn_start_time = gethrestime_sec(); + scn->scn_phys.scn_errors = 0; + scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc; + scn->scn_issued_before_pass = 0; + scn->scn_restart_txg = 0; + scn->scn_done_txg = 0; + scn->scn_last_checkpoint = 0; + scn->scn_checkpointing = B_FALSE; + spa_scan_stat_init(spa); + + if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) { + scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max; + + /* rewrite all disk labels */ + vdev_config_dirty(spa->spa_root_vdev); + + if (vdev_resilver_needed(spa->spa_root_vdev, + &scn->scn_phys.scn_min_txg, &scn->scn_phys.scn_max_txg)) { + nvlist_t *aux = fnvlist_alloc(); + fnvlist_add_string(aux, ZFS_EV_RESILVER_TYPE, + "healing"); + spa_event_notify(spa, NULL, aux, + ESC_ZFS_RESILVER_START); + nvlist_free(aux); + } else { + spa_event_notify(spa, NULL, NULL, ESC_ZFS_SCRUB_START); + } + + spa->spa_scrub_started = B_TRUE; + /* + * If this is an incremental scrub, limit the DDT scrub phase + * to just the auto-ditto class (for correctness); the rest + * of the scrub should go faster using top-down pruning. + */ + if (scn->scn_phys.scn_min_txg > TXG_INITIAL) + scn->scn_phys.scn_ddt_class_max = DDT_CLASS_DITTO; + + /* + * When starting a resilver clear any existing rebuild state. + * This is required to prevent stale rebuild status from + * being reported when a rebuild is run, then a resilver and + * finally a scrub. In which case only the scrub status + * should be reported by 'zpool status'. + */ + if (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) { + vdev_t *rvd = spa->spa_root_vdev; + for (uint64_t i = 0; i < rvd->vdev_children; i++) { + vdev_t *vd = rvd->vdev_child[i]; + vdev_rebuild_clear_sync( + (void *)(uintptr_t)vd->vdev_id, tx); + } + } + } + + /* back to the generic stuff */ + + if (dp->dp_blkstats == NULL) { + dp->dp_blkstats = + vmem_alloc(sizeof (zfs_all_blkstats_t), KM_SLEEP); + mutex_init(&dp->dp_blkstats->zab_lock, NULL, + MUTEX_DEFAULT, NULL); + } + bzero(&dp->dp_blkstats->zab_type, sizeof (dp->dp_blkstats->zab_type)); + + if (spa_version(spa) < SPA_VERSION_DSL_SCRUB) + ot = DMU_OT_ZAP_OTHER; + + scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset, + ot ? ot : DMU_OT_SCAN_QUEUE, DMU_OT_NONE, 0, tx); + + bcopy(&scn->scn_phys, &scn->scn_phys_cached, sizeof (scn->scn_phys)); + + dsl_scan_sync_state(scn, tx, SYNC_MANDATORY); + + spa_history_log_internal(spa, "scan setup", tx, + "func=%u mintxg=%llu maxtxg=%llu", + *funcp, (u_longlong_t)scn->scn_phys.scn_min_txg, + (u_longlong_t)scn->scn_phys.scn_max_txg); +} + +/* + * Called by the ZFS_IOC_POOL_SCAN ioctl to start a scrub or resilver. + * Can also be called to resume a paused scrub. + */ +int +dsl_scan(dsl_pool_t *dp, pool_scan_func_t func) +{ + spa_t *spa = dp->dp_spa; + dsl_scan_t *scn = dp->dp_scan; + + /* + * Purge all vdev caches and probe all devices. We do this here + * rather than in sync context because this requires a writer lock + * on the spa_config lock, which we can't do from sync context. The + * spa_scrub_reopen flag indicates that vdev_open() should not + * attempt to start another scrub. + */ + spa_vdev_state_enter(spa, SCL_NONE); + spa->spa_scrub_reopen = B_TRUE; + vdev_reopen(spa->spa_root_vdev); + spa->spa_scrub_reopen = B_FALSE; + (void) spa_vdev_state_exit(spa, NULL, 0); + + if (func == POOL_SCAN_RESILVER) { + dsl_scan_restart_resilver(spa->spa_dsl_pool, 0); + return (0); + } + + if (func == POOL_SCAN_SCRUB && dsl_scan_is_paused_scrub(scn)) { + /* got scrub start cmd, resume paused scrub */ + int err = dsl_scrub_set_pause_resume(scn->scn_dp, + POOL_SCRUB_NORMAL); + if (err == 0) { + spa_event_notify(spa, NULL, NULL, ESC_ZFS_SCRUB_RESUME); + return (SET_ERROR(ECANCELED)); + } + + return (SET_ERROR(err)); + } + + return (dsl_sync_task(spa_name(spa), dsl_scan_setup_check, + dsl_scan_setup_sync, &func, 0, ZFS_SPACE_CHECK_EXTRA_RESERVED)); +} + +/* ARGSUSED */ +static void +dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx) +{ + static const char *old_names[] = { + "scrub_bookmark", + "scrub_ddt_bookmark", + "scrub_ddt_class_max", + "scrub_queue", + "scrub_min_txg", + "scrub_max_txg", + "scrub_func", + "scrub_errors", + NULL + }; + + dsl_pool_t *dp = scn->scn_dp; + spa_t *spa = dp->dp_spa; + int i; + + /* Remove any remnants of an old-style scrub. */ + for (i = 0; old_names[i]; i++) { + (void) zap_remove(dp->dp_meta_objset, + DMU_POOL_DIRECTORY_OBJECT, old_names[i], tx); + } + + if (scn->scn_phys.scn_queue_obj != 0) { + VERIFY0(dmu_object_free(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, tx)); + scn->scn_phys.scn_queue_obj = 0; + } + scan_ds_queue_clear(scn); + scan_ds_prefetch_queue_clear(scn); + + scn->scn_phys.scn_flags &= ~DSF_SCRUB_PAUSED; + + /* + * If we were "restarted" from a stopped state, don't bother + * with anything else. + */ + if (!dsl_scan_is_running(scn)) { + ASSERT(!scn->scn_is_sorted); + return; + } + + if (scn->scn_is_sorted) { + scan_io_queues_destroy(scn); + scn->scn_is_sorted = B_FALSE; + + if (scn->scn_taskq != NULL) { + taskq_destroy(scn->scn_taskq); + scn->scn_taskq = NULL; + } + } + + scn->scn_phys.scn_state = complete ? DSS_FINISHED : DSS_CANCELED; + + spa_notify_waiters(spa); + + if (dsl_scan_restarting(scn, tx)) + spa_history_log_internal(spa, "scan aborted, restarting", tx, + "errors=%llu", (u_longlong_t)spa_get_errlog_size(spa)); + else if (!complete) + spa_history_log_internal(spa, "scan cancelled", tx, + "errors=%llu", (u_longlong_t)spa_get_errlog_size(spa)); + else + spa_history_log_internal(spa, "scan done", tx, + "errors=%llu", (u_longlong_t)spa_get_errlog_size(spa)); + + if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) { + spa->spa_scrub_active = B_FALSE; + + /* + * If the scrub/resilver completed, update all DTLs to + * reflect this. Whether it succeeded or not, vacate + * all temporary scrub DTLs. + * + * As the scrub does not currently support traversing + * data that have been freed but are part of a checkpoint, + * we don't mark the scrub as done in the DTLs as faults + * may still exist in those vdevs. + */ + if (complete && + !spa_feature_is_active(spa, SPA_FEATURE_POOL_CHECKPOINT)) { + vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg, + scn->scn_phys.scn_max_txg, B_TRUE, B_FALSE); + + if (scn->scn_phys.scn_min_txg) { + nvlist_t *aux = fnvlist_alloc(); + fnvlist_add_string(aux, ZFS_EV_RESILVER_TYPE, + "healing"); + spa_event_notify(spa, NULL, aux, + ESC_ZFS_RESILVER_FINISH); + nvlist_free(aux); + } else { + spa_event_notify(spa, NULL, NULL, + ESC_ZFS_SCRUB_FINISH); + } + } else { + vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg, + 0, B_TRUE, B_FALSE); + } + spa_errlog_rotate(spa); + + /* + * Don't clear flag until after vdev_dtl_reassess to ensure that + * DTL_MISSING will get updated when possible. + */ + spa->spa_scrub_started = B_FALSE; + + /* + * We may have finished replacing a device. + * Let the async thread assess this and handle the detach. + */ + spa_async_request(spa, SPA_ASYNC_RESILVER_DONE); + + /* + * Clear any resilver_deferred flags in the config. + * If there are drives that need resilvering, kick + * off an asynchronous request to start resilver. + * vdev_clear_resilver_deferred() may update the config + * before the resilver can restart. In the event of + * a crash during this period, the spa loading code + * will find the drives that need to be resilvered + * and start the resilver then. + */ + if (spa_feature_is_enabled(spa, SPA_FEATURE_RESILVER_DEFER) && + vdev_clear_resilver_deferred(spa->spa_root_vdev, tx)) { + spa_history_log_internal(spa, + "starting deferred resilver", tx, "errors=%llu", + (u_longlong_t)spa_get_errlog_size(spa)); + spa_async_request(spa, SPA_ASYNC_RESILVER); + } + } + + scn->scn_phys.scn_end_time = gethrestime_sec(); + + if (spa->spa_errata == ZPOOL_ERRATA_ZOL_2094_SCRUB) + spa->spa_errata = 0; + + ASSERT(!dsl_scan_is_running(scn)); +} + +/* ARGSUSED */ +static int +dsl_scan_cancel_check(void *arg, dmu_tx_t *tx) +{ + dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan; + + if (!dsl_scan_is_running(scn)) + return (SET_ERROR(ENOENT)); + return (0); +} + +/* ARGSUSED */ +static void +dsl_scan_cancel_sync(void *arg, dmu_tx_t *tx) +{ + dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan; + + dsl_scan_done(scn, B_FALSE, tx); + dsl_scan_sync_state(scn, tx, SYNC_MANDATORY); + spa_event_notify(scn->scn_dp->dp_spa, NULL, NULL, ESC_ZFS_SCRUB_ABORT); +} + +int +dsl_scan_cancel(dsl_pool_t *dp) +{ + return (dsl_sync_task(spa_name(dp->dp_spa), dsl_scan_cancel_check, + dsl_scan_cancel_sync, NULL, 3, ZFS_SPACE_CHECK_RESERVED)); +} + +static int +dsl_scrub_pause_resume_check(void *arg, dmu_tx_t *tx) +{ + pool_scrub_cmd_t *cmd = arg; + dsl_pool_t *dp = dmu_tx_pool(tx); + dsl_scan_t *scn = dp->dp_scan; + + if (*cmd == POOL_SCRUB_PAUSE) { + /* can't pause a scrub when there is no in-progress scrub */ + if (!dsl_scan_scrubbing(dp)) + return (SET_ERROR(ENOENT)); + + /* can't pause a paused scrub */ + if (dsl_scan_is_paused_scrub(scn)) + return (SET_ERROR(EBUSY)); + } else if (*cmd != POOL_SCRUB_NORMAL) { + return (SET_ERROR(ENOTSUP)); + } + + return (0); +} + +static void +dsl_scrub_pause_resume_sync(void *arg, dmu_tx_t *tx) +{ + pool_scrub_cmd_t *cmd = arg; + dsl_pool_t *dp = dmu_tx_pool(tx); + spa_t *spa = dp->dp_spa; + dsl_scan_t *scn = dp->dp_scan; + + if (*cmd == POOL_SCRUB_PAUSE) { + /* can't pause a scrub when there is no in-progress scrub */ + spa->spa_scan_pass_scrub_pause = gethrestime_sec(); + scn->scn_phys.scn_flags |= DSF_SCRUB_PAUSED; + scn->scn_phys_cached.scn_flags |= DSF_SCRUB_PAUSED; + dsl_scan_sync_state(scn, tx, SYNC_CACHED); + spa_event_notify(spa, NULL, NULL, ESC_ZFS_SCRUB_PAUSED); + spa_notify_waiters(spa); + } else { + ASSERT3U(*cmd, ==, POOL_SCRUB_NORMAL); + if (dsl_scan_is_paused_scrub(scn)) { + /* + * We need to keep track of how much time we spend + * paused per pass so that we can adjust the scrub rate + * shown in the output of 'zpool status' + */ + spa->spa_scan_pass_scrub_spent_paused += + gethrestime_sec() - spa->spa_scan_pass_scrub_pause; + spa->spa_scan_pass_scrub_pause = 0; + scn->scn_phys.scn_flags &= ~DSF_SCRUB_PAUSED; + scn->scn_phys_cached.scn_flags &= ~DSF_SCRUB_PAUSED; + dsl_scan_sync_state(scn, tx, SYNC_CACHED); + } + } +} + +/* + * Set scrub pause/resume state if it makes sense to do so + */ +int +dsl_scrub_set_pause_resume(const dsl_pool_t *dp, pool_scrub_cmd_t cmd) +{ + return (dsl_sync_task(spa_name(dp->dp_spa), + dsl_scrub_pause_resume_check, dsl_scrub_pause_resume_sync, &cmd, 3, + ZFS_SPACE_CHECK_RESERVED)); +} + + +/* start a new scan, or restart an existing one. */ +void +dsl_scan_restart_resilver(dsl_pool_t *dp, uint64_t txg) +{ + if (txg == 0) { + dmu_tx_t *tx; + tx = dmu_tx_create_dd(dp->dp_mos_dir); + VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT)); + + txg = dmu_tx_get_txg(tx); + dp->dp_scan->scn_restart_txg = txg; + dmu_tx_commit(tx); + } else { + dp->dp_scan->scn_restart_txg = txg; + } + zfs_dbgmsg("restarting resilver txg=%llu", (longlong_t)txg); +} + +void +dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bp) +{ + zio_free(dp->dp_spa, txg, bp); +} + +void +dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp) +{ + ASSERT(dsl_pool_sync_context(dp)); + zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, pio->io_flags)); +} + +static int +scan_ds_queue_compare(const void *a, const void *b) +{ + const scan_ds_t *sds_a = a, *sds_b = b; + + if (sds_a->sds_dsobj < sds_b->sds_dsobj) + return (-1); + if (sds_a->sds_dsobj == sds_b->sds_dsobj) + return (0); + return (1); +} + +static void +scan_ds_queue_clear(dsl_scan_t *scn) +{ + void *cookie = NULL; + scan_ds_t *sds; + while ((sds = avl_destroy_nodes(&scn->scn_queue, &cookie)) != NULL) { + kmem_free(sds, sizeof (*sds)); + } +} + +static boolean_t +scan_ds_queue_contains(dsl_scan_t *scn, uint64_t dsobj, uint64_t *txg) +{ + scan_ds_t srch, *sds; + + srch.sds_dsobj = dsobj; + sds = avl_find(&scn->scn_queue, &srch, NULL); + if (sds != NULL && txg != NULL) + *txg = sds->sds_txg; + return (sds != NULL); +} + +static void +scan_ds_queue_insert(dsl_scan_t *scn, uint64_t dsobj, uint64_t txg) +{ + scan_ds_t *sds; + avl_index_t where; + + sds = kmem_zalloc(sizeof (*sds), KM_SLEEP); + sds->sds_dsobj = dsobj; + sds->sds_txg = txg; + + VERIFY3P(avl_find(&scn->scn_queue, sds, &where), ==, NULL); + avl_insert(&scn->scn_queue, sds, where); +} + +static void +scan_ds_queue_remove(dsl_scan_t *scn, uint64_t dsobj) +{ + scan_ds_t srch, *sds; + + srch.sds_dsobj = dsobj; + + sds = avl_find(&scn->scn_queue, &srch, NULL); + VERIFY(sds != NULL); + avl_remove(&scn->scn_queue, sds); + kmem_free(sds, sizeof (*sds)); +} + +static void +scan_ds_queue_sync(dsl_scan_t *scn, dmu_tx_t *tx) +{ + dsl_pool_t *dp = scn->scn_dp; + spa_t *spa = dp->dp_spa; + dmu_object_type_t ot = (spa_version(spa) >= SPA_VERSION_DSL_SCRUB) ? + DMU_OT_SCAN_QUEUE : DMU_OT_ZAP_OTHER; + + ASSERT0(scn->scn_bytes_pending); + ASSERT(scn->scn_phys.scn_queue_obj != 0); + + VERIFY0(dmu_object_free(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, tx)); + scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset, ot, + DMU_OT_NONE, 0, tx); + for (scan_ds_t *sds = avl_first(&scn->scn_queue); + sds != NULL; sds = AVL_NEXT(&scn->scn_queue, sds)) { + VERIFY0(zap_add_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, sds->sds_dsobj, + sds->sds_txg, tx)); + } +} + +/* + * Computes the memory limit state that we're currently in. A sorted scan + * needs quite a bit of memory to hold the sorting queue, so we need to + * reasonably constrain the size so it doesn't impact overall system + * performance. We compute two limits: + * 1) Hard memory limit: if the amount of memory used by the sorting + * queues on a pool gets above this value, we stop the metadata + * scanning portion and start issuing the queued up and sorted + * I/Os to reduce memory usage. + * This limit is calculated as a fraction of physmem (by default 5%). + * We constrain the lower bound of the hard limit to an absolute + * minimum of zfs_scan_mem_lim_min (default: 16 MiB). We also constrain + * the upper bound to 5% of the total pool size - no chance we'll + * ever need that much memory, but just to keep the value in check. + * 2) Soft memory limit: once we hit the hard memory limit, we start + * issuing I/O to reduce queue memory usage, but we don't want to + * completely empty out the queues, since we might be able to find I/Os + * that will fill in the gaps of our non-sequential IOs at some point + * in the future. So we stop the issuing of I/Os once the amount of + * memory used drops below the soft limit (at which point we stop issuing + * I/O and start scanning metadata again). + * + * This limit is calculated by subtracting a fraction of the hard + * limit from the hard limit. By default this fraction is 5%, so + * the soft limit is 95% of the hard limit. We cap the size of the + * difference between the hard and soft limits at an absolute + * maximum of zfs_scan_mem_lim_soft_max (default: 128 MiB) - this is + * sufficient to not cause too frequent switching between the + * metadata scan and I/O issue (even at 2k recordsize, 128 MiB's + * worth of queues is about 1.2 GiB of on-pool data, so scanning + * that should take at least a decent fraction of a second). + */ +static boolean_t +dsl_scan_should_clear(dsl_scan_t *scn) +{ + spa_t *spa = scn->scn_dp->dp_spa; + vdev_t *rvd = scn->scn_dp->dp_spa->spa_root_vdev; + uint64_t alloc, mlim_hard, mlim_soft, mused; + + alloc = metaslab_class_get_alloc(spa_normal_class(spa)); + alloc += metaslab_class_get_alloc(spa_special_class(spa)); + alloc += metaslab_class_get_alloc(spa_dedup_class(spa)); + + mlim_hard = MAX((physmem / zfs_scan_mem_lim_fact) * PAGESIZE, + zfs_scan_mem_lim_min); + mlim_hard = MIN(mlim_hard, alloc / 20); + mlim_soft = mlim_hard - MIN(mlim_hard / zfs_scan_mem_lim_soft_fact, + zfs_scan_mem_lim_soft_max); + mused = 0; + for (uint64_t i = 0; i < rvd->vdev_children; i++) { + vdev_t *tvd = rvd->vdev_child[i]; + dsl_scan_io_queue_t *queue; + + mutex_enter(&tvd->vdev_scan_io_queue_lock); + queue = tvd->vdev_scan_io_queue; + if (queue != NULL) { + /* # extents in exts_by_size = # in exts_by_addr */ + mused += zfs_btree_numnodes(&queue->q_exts_by_size) * + sizeof (range_seg_gap_t) + queue->q_sio_memused; + } + mutex_exit(&tvd->vdev_scan_io_queue_lock); + } + + dprintf("current scan memory usage: %llu bytes\n", (longlong_t)mused); + + if (mused == 0) + ASSERT0(scn->scn_bytes_pending); + + /* + * If we are above our hard limit, we need to clear out memory. + * If we are below our soft limit, we need to accumulate sequential IOs. + * Otherwise, we should keep doing whatever we are currently doing. + */ + if (mused >= mlim_hard) + return (B_TRUE); + else if (mused < mlim_soft) + return (B_FALSE); + else + return (scn->scn_clearing); +} + +static boolean_t +dsl_scan_check_suspend(dsl_scan_t *scn, const zbookmark_phys_t *zb) +{ + /* we never skip user/group accounting objects */ + if (zb && (int64_t)zb->zb_object < 0) + return (B_FALSE); + + if (scn->scn_suspending) + return (B_TRUE); /* we're already suspending */ + + if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark)) + return (B_FALSE); /* we're resuming */ + + /* We only know how to resume from level-0 and objset blocks. */ + if (zb && (zb->zb_level != 0 && zb->zb_level != ZB_ROOT_LEVEL)) + return (B_FALSE); + + /* + * We suspend if: + * - we have scanned for at least the minimum time (default 1 sec + * for scrub, 3 sec for resilver), and either we have sufficient + * dirty data that we are starting to write more quickly + * (default 30%), someone is explicitly waiting for this txg + * to complete, or we have used up all of the time in the txg + * timeout (default 5 sec). + * or + * - the spa is shutting down because this pool is being exported + * or the machine is rebooting. + * or + * - the scan queue has reached its memory use limit + */ + uint64_t curr_time_ns = gethrtime(); + uint64_t scan_time_ns = curr_time_ns - scn->scn_sync_start_time; + uint64_t sync_time_ns = curr_time_ns - + scn->scn_dp->dp_spa->spa_sync_starttime; + int dirty_pct = scn->scn_dp->dp_dirty_total * 100 / zfs_dirty_data_max; + int mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ? + zfs_resilver_min_time_ms : zfs_scrub_min_time_ms; + + if ((NSEC2MSEC(scan_time_ns) > mintime && + (dirty_pct >= zfs_vdev_async_write_active_min_dirty_percent || + txg_sync_waiting(scn->scn_dp) || + NSEC2SEC(sync_time_ns) >= zfs_txg_timeout)) || + spa_shutting_down(scn->scn_dp->dp_spa) || + (zfs_scan_strict_mem_lim && dsl_scan_should_clear(scn))) { + if (zb && zb->zb_level == ZB_ROOT_LEVEL) { + dprintf("suspending at first available bookmark " + "%llx/%llx/%llx/%llx\n", + (longlong_t)zb->zb_objset, + (longlong_t)zb->zb_object, + (longlong_t)zb->zb_level, + (longlong_t)zb->zb_blkid); + SET_BOOKMARK(&scn->scn_phys.scn_bookmark, + zb->zb_objset, 0, 0, 0); + } else if (zb != NULL) { + dprintf("suspending at bookmark %llx/%llx/%llx/%llx\n", + (longlong_t)zb->zb_objset, + (longlong_t)zb->zb_object, + (longlong_t)zb->zb_level, + (longlong_t)zb->zb_blkid); + scn->scn_phys.scn_bookmark = *zb; + } else { +#ifdef ZFS_DEBUG + dsl_scan_phys_t *scnp = &scn->scn_phys; + dprintf("suspending at at DDT bookmark " + "%llx/%llx/%llx/%llx\n", + (longlong_t)scnp->scn_ddt_bookmark.ddb_class, + (longlong_t)scnp->scn_ddt_bookmark.ddb_type, + (longlong_t)scnp->scn_ddt_bookmark.ddb_checksum, + (longlong_t)scnp->scn_ddt_bookmark.ddb_cursor); +#endif + } + scn->scn_suspending = B_TRUE; + return (B_TRUE); + } + return (B_FALSE); +} + +typedef struct zil_scan_arg { + dsl_pool_t *zsa_dp; + zil_header_t *zsa_zh; +} zil_scan_arg_t; + +/* ARGSUSED */ +static int +dsl_scan_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg) +{ + zil_scan_arg_t *zsa = arg; + dsl_pool_t *dp = zsa->zsa_dp; + dsl_scan_t *scn = dp->dp_scan; + zil_header_t *zh = zsa->zsa_zh; + zbookmark_phys_t zb; + + ASSERT(!BP_IS_REDACTED(bp)); + if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_cur_min_txg) + return (0); + + /* + * One block ("stubby") can be allocated a long time ago; we + * want to visit that one because it has been allocated + * (on-disk) even if it hasn't been claimed (even though for + * scrub there's nothing to do to it). + */ + if (claim_txg == 0 && bp->blk_birth >= spa_min_claim_txg(dp->dp_spa)) + return (0); + + SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET], + ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]); + + VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb)); + return (0); +} + +/* ARGSUSED */ +static int +dsl_scan_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg) +{ + if (lrc->lrc_txtype == TX_WRITE) { + zil_scan_arg_t *zsa = arg; + dsl_pool_t *dp = zsa->zsa_dp; + dsl_scan_t *scn = dp->dp_scan; + zil_header_t *zh = zsa->zsa_zh; + lr_write_t *lr = (lr_write_t *)lrc; + blkptr_t *bp = &lr->lr_blkptr; + zbookmark_phys_t zb; + + ASSERT(!BP_IS_REDACTED(bp)); + if (BP_IS_HOLE(bp) || + bp->blk_birth <= scn->scn_phys.scn_cur_min_txg) + return (0); + + /* + * birth can be < claim_txg if this record's txg is + * already txg sync'ed (but this log block contains + * other records that are not synced) + */ + if (claim_txg == 0 || bp->blk_birth < claim_txg) + return (0); + + SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET], + lr->lr_foid, ZB_ZIL_LEVEL, + lr->lr_offset / BP_GET_LSIZE(bp)); + + VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb)); + } + return (0); +} + +static void +dsl_scan_zil(dsl_pool_t *dp, zil_header_t *zh) +{ + uint64_t claim_txg = zh->zh_claim_txg; + zil_scan_arg_t zsa = { dp, zh }; + zilog_t *zilog; + + ASSERT(spa_writeable(dp->dp_spa)); + + /* + * We only want to visit blocks that have been claimed but not yet + * replayed (or, in read-only mode, blocks that *would* be claimed). + */ + if (claim_txg == 0) + return; + + zilog = zil_alloc(dp->dp_meta_objset, zh); + + (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa, + claim_txg, B_FALSE); + + zil_free(zilog); +} + +/* + * We compare scan_prefetch_issue_ctx_t's based on their bookmarks. The idea + * here is to sort the AVL tree by the order each block will be needed. + */ +static int +scan_prefetch_queue_compare(const void *a, const void *b) +{ + const scan_prefetch_issue_ctx_t *spic_a = a, *spic_b = b; + const scan_prefetch_ctx_t *spc_a = spic_a->spic_spc; + const scan_prefetch_ctx_t *spc_b = spic_b->spic_spc; + + return (zbookmark_compare(spc_a->spc_datablkszsec, + spc_a->spc_indblkshift, spc_b->spc_datablkszsec, + spc_b->spc_indblkshift, &spic_a->spic_zb, &spic_b->spic_zb)); +} + +static void +scan_prefetch_ctx_rele(scan_prefetch_ctx_t *spc, void *tag) +{ + if (zfs_refcount_remove(&spc->spc_refcnt, tag) == 0) { + zfs_refcount_destroy(&spc->spc_refcnt); + kmem_free(spc, sizeof (scan_prefetch_ctx_t)); + } +} + +static scan_prefetch_ctx_t * +scan_prefetch_ctx_create(dsl_scan_t *scn, dnode_phys_t *dnp, void *tag) +{ + scan_prefetch_ctx_t *spc; + + spc = kmem_alloc(sizeof (scan_prefetch_ctx_t), KM_SLEEP); + zfs_refcount_create(&spc->spc_refcnt); + zfs_refcount_add(&spc->spc_refcnt, tag); + spc->spc_scn = scn; + if (dnp != NULL) { + spc->spc_datablkszsec = dnp->dn_datablkszsec; + spc->spc_indblkshift = dnp->dn_indblkshift; + spc->spc_root = B_FALSE; + } else { + spc->spc_datablkszsec = 0; + spc->spc_indblkshift = 0; + spc->spc_root = B_TRUE; + } + + return (spc); +} + +static void +scan_prefetch_ctx_add_ref(scan_prefetch_ctx_t *spc, void *tag) +{ + zfs_refcount_add(&spc->spc_refcnt, tag); +} + +static void +scan_ds_prefetch_queue_clear(dsl_scan_t *scn) +{ + spa_t *spa = scn->scn_dp->dp_spa; + void *cookie = NULL; + scan_prefetch_issue_ctx_t *spic = NULL; + + mutex_enter(&spa->spa_scrub_lock); + while ((spic = avl_destroy_nodes(&scn->scn_prefetch_queue, + &cookie)) != NULL) { + scan_prefetch_ctx_rele(spic->spic_spc, scn); + kmem_free(spic, sizeof (scan_prefetch_issue_ctx_t)); + } + mutex_exit(&spa->spa_scrub_lock); +} + +static boolean_t +dsl_scan_check_prefetch_resume(scan_prefetch_ctx_t *spc, + const zbookmark_phys_t *zb) +{ + zbookmark_phys_t *last_zb = &spc->spc_scn->scn_prefetch_bookmark; + dnode_phys_t tmp_dnp; + dnode_phys_t *dnp = (spc->spc_root) ? NULL : &tmp_dnp; + + if (zb->zb_objset != last_zb->zb_objset) + return (B_TRUE); + if ((int64_t)zb->zb_object < 0) + return (B_FALSE); + + tmp_dnp.dn_datablkszsec = spc->spc_datablkszsec; + tmp_dnp.dn_indblkshift = spc->spc_indblkshift; + + if (zbookmark_subtree_completed(dnp, zb, last_zb)) + return (B_TRUE); + + return (B_FALSE); +} + +static void +dsl_scan_prefetch(scan_prefetch_ctx_t *spc, blkptr_t *bp, zbookmark_phys_t *zb) +{ + avl_index_t idx; + dsl_scan_t *scn = spc->spc_scn; + spa_t *spa = scn->scn_dp->dp_spa; + scan_prefetch_issue_ctx_t *spic; + + if (zfs_no_scrub_prefetch || BP_IS_REDACTED(bp)) + return; + + if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_cur_min_txg || + (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE && + BP_GET_TYPE(bp) != DMU_OT_OBJSET)) + return; + + if (dsl_scan_check_prefetch_resume(spc, zb)) + return; + + scan_prefetch_ctx_add_ref(spc, scn); + spic = kmem_alloc(sizeof (scan_prefetch_issue_ctx_t), KM_SLEEP); + spic->spic_spc = spc; + spic->spic_bp = *bp; + spic->spic_zb = *zb; + + /* + * Add the IO to the queue of blocks to prefetch. This allows us to + * prioritize blocks that we will need first for the main traversal + * thread. + */ + mutex_enter(&spa->spa_scrub_lock); + if (avl_find(&scn->scn_prefetch_queue, spic, &idx) != NULL) { + /* this block is already queued for prefetch */ + kmem_free(spic, sizeof (scan_prefetch_issue_ctx_t)); + scan_prefetch_ctx_rele(spc, scn); + mutex_exit(&spa->spa_scrub_lock); + return; + } + + avl_insert(&scn->scn_prefetch_queue, spic, idx); + cv_broadcast(&spa->spa_scrub_io_cv); + mutex_exit(&spa->spa_scrub_lock); +} + +static void +dsl_scan_prefetch_dnode(dsl_scan_t *scn, dnode_phys_t *dnp, + uint64_t objset, uint64_t object) +{ + int i; + zbookmark_phys_t zb; + scan_prefetch_ctx_t *spc; + + if (dnp->dn_nblkptr == 0 && !(dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) + return; + + SET_BOOKMARK(&zb, objset, object, 0, 0); + + spc = scan_prefetch_ctx_create(scn, dnp, FTAG); + + for (i = 0; i < dnp->dn_nblkptr; i++) { + zb.zb_level = BP_GET_LEVEL(&dnp->dn_blkptr[i]); + zb.zb_blkid = i; + dsl_scan_prefetch(spc, &dnp->dn_blkptr[i], &zb); + } + + if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) { + zb.zb_level = 0; + zb.zb_blkid = DMU_SPILL_BLKID; + dsl_scan_prefetch(spc, DN_SPILL_BLKPTR(dnp), &zb); + } + + scan_prefetch_ctx_rele(spc, FTAG); +} + +static void +dsl_scan_prefetch_cb(zio_t *zio, const zbookmark_phys_t *zb, const blkptr_t *bp, + arc_buf_t *buf, void *private) +{ + scan_prefetch_ctx_t *spc = private; + dsl_scan_t *scn = spc->spc_scn; + spa_t *spa = scn->scn_dp->dp_spa; + + /* broadcast that the IO has completed for rate limiting purposes */ + mutex_enter(&spa->spa_scrub_lock); + ASSERT3U(spa->spa_scrub_inflight, >=, BP_GET_PSIZE(bp)); + spa->spa_scrub_inflight -= BP_GET_PSIZE(bp); + cv_broadcast(&spa->spa_scrub_io_cv); + mutex_exit(&spa->spa_scrub_lock); + + /* if there was an error or we are done prefetching, just cleanup */ + if (buf == NULL || scn->scn_prefetch_stop) + goto out; + + if (BP_GET_LEVEL(bp) > 0) { + int i; + blkptr_t *cbp; + int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT; + zbookmark_phys_t czb; + + for (i = 0, cbp = buf->b_data; i < epb; i++, cbp++) { + SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object, + zb->zb_level - 1, zb->zb_blkid * epb + i); + dsl_scan_prefetch(spc, cbp, &czb); + } + } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) { + dnode_phys_t *cdnp; + int i; + int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT; + + for (i = 0, cdnp = buf->b_data; i < epb; + i += cdnp->dn_extra_slots + 1, + cdnp += cdnp->dn_extra_slots + 1) { + dsl_scan_prefetch_dnode(scn, cdnp, + zb->zb_objset, zb->zb_blkid * epb + i); + } + } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) { + objset_phys_t *osp = buf->b_data; + + dsl_scan_prefetch_dnode(scn, &osp->os_meta_dnode, + zb->zb_objset, DMU_META_DNODE_OBJECT); + + if (OBJSET_BUF_HAS_USERUSED(buf)) { + dsl_scan_prefetch_dnode(scn, + &osp->os_groupused_dnode, zb->zb_objset, + DMU_GROUPUSED_OBJECT); + dsl_scan_prefetch_dnode(scn, + &osp->os_userused_dnode, zb->zb_objset, + DMU_USERUSED_OBJECT); + } + } + +out: + if (buf != NULL) + arc_buf_destroy(buf, private); + scan_prefetch_ctx_rele(spc, scn); +} + +/* ARGSUSED */ +static void +dsl_scan_prefetch_thread(void *arg) +{ + dsl_scan_t *scn = arg; + spa_t *spa = scn->scn_dp->dp_spa; + scan_prefetch_issue_ctx_t *spic; + + /* loop until we are told to stop */ + while (!scn->scn_prefetch_stop) { + arc_flags_t flags = ARC_FLAG_NOWAIT | + ARC_FLAG_PRESCIENT_PREFETCH | ARC_FLAG_PREFETCH; + int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD; + + mutex_enter(&spa->spa_scrub_lock); + + /* + * Wait until we have an IO to issue and are not above our + * maximum in flight limit. + */ + while (!scn->scn_prefetch_stop && + (avl_numnodes(&scn->scn_prefetch_queue) == 0 || + spa->spa_scrub_inflight >= scn->scn_maxinflight_bytes)) { + cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock); + } + + /* recheck if we should stop since we waited for the cv */ + if (scn->scn_prefetch_stop) { + mutex_exit(&spa->spa_scrub_lock); + break; + } + + /* remove the prefetch IO from the tree */ + spic = avl_first(&scn->scn_prefetch_queue); + spa->spa_scrub_inflight += BP_GET_PSIZE(&spic->spic_bp); + avl_remove(&scn->scn_prefetch_queue, spic); + + mutex_exit(&spa->spa_scrub_lock); + + if (BP_IS_PROTECTED(&spic->spic_bp)) { + ASSERT(BP_GET_TYPE(&spic->spic_bp) == DMU_OT_DNODE || + BP_GET_TYPE(&spic->spic_bp) == DMU_OT_OBJSET); + ASSERT3U(BP_GET_LEVEL(&spic->spic_bp), ==, 0); + zio_flags |= ZIO_FLAG_RAW; + } + + /* issue the prefetch asynchronously */ + (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, + &spic->spic_bp, dsl_scan_prefetch_cb, spic->spic_spc, + ZIO_PRIORITY_SCRUB, zio_flags, &flags, &spic->spic_zb); + + kmem_free(spic, sizeof (scan_prefetch_issue_ctx_t)); + } + + ASSERT(scn->scn_prefetch_stop); + + /* free any prefetches we didn't get to complete */ + mutex_enter(&spa->spa_scrub_lock); + while ((spic = avl_first(&scn->scn_prefetch_queue)) != NULL) { + avl_remove(&scn->scn_prefetch_queue, spic); + scan_prefetch_ctx_rele(spic->spic_spc, scn); + kmem_free(spic, sizeof (scan_prefetch_issue_ctx_t)); + } + ASSERT0(avl_numnodes(&scn->scn_prefetch_queue)); + mutex_exit(&spa->spa_scrub_lock); +} + +static boolean_t +dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp, + const zbookmark_phys_t *zb) +{ + /* + * We never skip over user/group accounting objects (obj<0) + */ + if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark) && + (int64_t)zb->zb_object >= 0) { + /* + * If we already visited this bp & everything below (in + * a prior txg sync), don't bother doing it again. + */ + if (zbookmark_subtree_completed(dnp, zb, + &scn->scn_phys.scn_bookmark)) + return (B_TRUE); + + /* + * If we found the block we're trying to resume from, or + * we went past it to a different object, zero it out to + * indicate that it's OK to start checking for suspending + * again. + */ + if (bcmp(zb, &scn->scn_phys.scn_bookmark, sizeof (*zb)) == 0 || + zb->zb_object > scn->scn_phys.scn_bookmark.zb_object) { + dprintf("resuming at %llx/%llx/%llx/%llx\n", + (longlong_t)zb->zb_objset, + (longlong_t)zb->zb_object, + (longlong_t)zb->zb_level, + (longlong_t)zb->zb_blkid); + bzero(&scn->scn_phys.scn_bookmark, sizeof (*zb)); + } + } + return (B_FALSE); +} + +static void dsl_scan_visitbp(blkptr_t *bp, const zbookmark_phys_t *zb, + dnode_phys_t *dnp, dsl_dataset_t *ds, dsl_scan_t *scn, + dmu_objset_type_t ostype, dmu_tx_t *tx); +inline __attribute__((always_inline)) static void dsl_scan_visitdnode( + dsl_scan_t *, dsl_dataset_t *ds, dmu_objset_type_t ostype, + dnode_phys_t *dnp, uint64_t object, dmu_tx_t *tx); + +/* + * Return nonzero on i/o error. + * Return new buf to write out in *bufp. + */ +inline __attribute__((always_inline)) static int +dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype, + dnode_phys_t *dnp, const blkptr_t *bp, + const zbookmark_phys_t *zb, dmu_tx_t *tx) +{ + dsl_pool_t *dp = scn->scn_dp; + int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD; + int err; + + ASSERT(!BP_IS_REDACTED(bp)); + + if (BP_GET_LEVEL(bp) > 0) { + arc_flags_t flags = ARC_FLAG_WAIT; + int i; + blkptr_t *cbp; + int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT; + arc_buf_t *buf; + + err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf, + ZIO_PRIORITY_SCRUB, zio_flags, &flags, zb); + if (err) { + scn->scn_phys.scn_errors++; + return (err); + } + for (i = 0, cbp = buf->b_data; i < epb; i++, cbp++) { + zbookmark_phys_t czb; + + SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object, + zb->zb_level - 1, + zb->zb_blkid * epb + i); + dsl_scan_visitbp(cbp, &czb, dnp, + ds, scn, ostype, tx); + } + arc_buf_destroy(buf, &buf); + } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) { + arc_flags_t flags = ARC_FLAG_WAIT; + dnode_phys_t *cdnp; + int i; + int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT; + arc_buf_t *buf; + + if (BP_IS_PROTECTED(bp)) { + ASSERT3U(BP_GET_COMPRESS(bp), ==, ZIO_COMPRESS_OFF); + zio_flags |= ZIO_FLAG_RAW; + } + + err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf, + ZIO_PRIORITY_SCRUB, zio_flags, &flags, zb); + if (err) { + scn->scn_phys.scn_errors++; + return (err); + } + for (i = 0, cdnp = buf->b_data; i < epb; + i += cdnp->dn_extra_slots + 1, + cdnp += cdnp->dn_extra_slots + 1) { + dsl_scan_visitdnode(scn, ds, ostype, + cdnp, zb->zb_blkid * epb + i, tx); + } + + arc_buf_destroy(buf, &buf); + } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) { + arc_flags_t flags = ARC_FLAG_WAIT; + objset_phys_t *osp; + arc_buf_t *buf; + + err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf, + ZIO_PRIORITY_SCRUB, zio_flags, &flags, zb); + if (err) { + scn->scn_phys.scn_errors++; + return (err); + } + + osp = buf->b_data; + + dsl_scan_visitdnode(scn, ds, osp->os_type, + &osp->os_meta_dnode, DMU_META_DNODE_OBJECT, tx); + + if (OBJSET_BUF_HAS_USERUSED(buf)) { + /* + * We also always visit user/group/project accounting + * objects, and never skip them, even if we are + * suspending. This is necessary so that the + * space deltas from this txg get integrated. + */ + if (OBJSET_BUF_HAS_PROJECTUSED(buf)) + dsl_scan_visitdnode(scn, ds, osp->os_type, + &osp->os_projectused_dnode, + DMU_PROJECTUSED_OBJECT, tx); + dsl_scan_visitdnode(scn, ds, osp->os_type, + &osp->os_groupused_dnode, + DMU_GROUPUSED_OBJECT, tx); + dsl_scan_visitdnode(scn, ds, osp->os_type, + &osp->os_userused_dnode, + DMU_USERUSED_OBJECT, tx); + } + arc_buf_destroy(buf, &buf); + } + + return (0); +} + +inline __attribute__((always_inline)) static void +dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds, + dmu_objset_type_t ostype, dnode_phys_t *dnp, + uint64_t object, dmu_tx_t *tx) +{ + int j; + + for (j = 0; j < dnp->dn_nblkptr; j++) { + zbookmark_phys_t czb; + + SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object, + dnp->dn_nlevels - 1, j); + dsl_scan_visitbp(&dnp->dn_blkptr[j], + &czb, dnp, ds, scn, ostype, tx); + } + + if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) { + zbookmark_phys_t czb; + SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object, + 0, DMU_SPILL_BLKID); + dsl_scan_visitbp(DN_SPILL_BLKPTR(dnp), + &czb, dnp, ds, scn, ostype, tx); + } +} + +/* + * The arguments are in this order because mdb can only print the + * first 5; we want them to be useful. + */ +static void +dsl_scan_visitbp(blkptr_t *bp, const zbookmark_phys_t *zb, + dnode_phys_t *dnp, dsl_dataset_t *ds, dsl_scan_t *scn, + dmu_objset_type_t ostype, dmu_tx_t *tx) +{ + dsl_pool_t *dp = scn->scn_dp; + blkptr_t *bp_toread = NULL; + + if (dsl_scan_check_suspend(scn, zb)) + return; + + if (dsl_scan_check_resume(scn, dnp, zb)) + return; + + scn->scn_visited_this_txg++; + + /* + * This debugging is commented out to conserve stack space. This + * function is called recursively and the debugging adds several + * bytes to the stack for each call. It can be commented back in + * if required to debug an issue in dsl_scan_visitbp(). + * + * dprintf_bp(bp, + * "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx bp=%p", + * ds, ds ? ds->ds_object : 0, + * zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid, + * bp); + */ + + if (BP_IS_HOLE(bp)) { + scn->scn_holes_this_txg++; + return; + } + + if (BP_IS_REDACTED(bp)) { + ASSERT(dsl_dataset_feature_is_active(ds, + SPA_FEATURE_REDACTED_DATASETS)); + return; + } + + if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg) { + scn->scn_lt_min_this_txg++; + return; + } + + bp_toread = kmem_alloc(sizeof (blkptr_t), KM_SLEEP); + *bp_toread = *bp; + + if (dsl_scan_recurse(scn, ds, ostype, dnp, bp_toread, zb, tx) != 0) + goto out; + + /* + * If dsl_scan_ddt() has already visited this block, it will have + * already done any translations or scrubbing, so don't call the + * callback again. + */ + if (ddt_class_contains(dp->dp_spa, + scn->scn_phys.scn_ddt_class_max, bp)) { + scn->scn_ddt_contained_this_txg++; + goto out; + } + + /* + * If this block is from the future (after cur_max_txg), then we + * are doing this on behalf of a deleted snapshot, and we will + * revisit the future block on the next pass of this dataset. + * Don't scan it now unless we need to because something + * under it was modified. + */ + if (BP_PHYSICAL_BIRTH(bp) > scn->scn_phys.scn_cur_max_txg) { + scn->scn_gt_max_this_txg++; + goto out; + } + + scan_funcs[scn->scn_phys.scn_func](dp, bp, zb); + +out: + kmem_free(bp_toread, sizeof (blkptr_t)); +} + +static void +dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp, + dmu_tx_t *tx) +{ + zbookmark_phys_t zb; + scan_prefetch_ctx_t *spc; + + SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET, + ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID); + + if (ZB_IS_ZERO(&scn->scn_phys.scn_bookmark)) { + SET_BOOKMARK(&scn->scn_prefetch_bookmark, + zb.zb_objset, 0, 0, 0); + } else { + scn->scn_prefetch_bookmark = scn->scn_phys.scn_bookmark; + } + + scn->scn_objsets_visited_this_txg++; + + spc = scan_prefetch_ctx_create(scn, NULL, FTAG); + dsl_scan_prefetch(spc, bp, &zb); + scan_prefetch_ctx_rele(spc, FTAG); + + dsl_scan_visitbp(bp, &zb, NULL, ds, scn, DMU_OST_NONE, tx); + + dprintf_ds(ds, "finished scan%s", ""); +} + +static void +ds_destroyed_scn_phys(dsl_dataset_t *ds, dsl_scan_phys_t *scn_phys) +{ + if (scn_phys->scn_bookmark.zb_objset == ds->ds_object) { + if (ds->ds_is_snapshot) { + /* + * Note: + * - scn_cur_{min,max}_txg stays the same. + * - Setting the flag is not really necessary if + * scn_cur_max_txg == scn_max_txg, because there + * is nothing after this snapshot that we care + * about. However, we set it anyway and then + * ignore it when we retraverse it in + * dsl_scan_visitds(). + */ + scn_phys->scn_bookmark.zb_objset = + dsl_dataset_phys(ds)->ds_next_snap_obj; + zfs_dbgmsg("destroying ds %llu; currently traversing; " + "reset zb_objset to %llu", + (u_longlong_t)ds->ds_object, + (u_longlong_t)dsl_dataset_phys(ds)-> + ds_next_snap_obj); + scn_phys->scn_flags |= DSF_VISIT_DS_AGAIN; + } else { + SET_BOOKMARK(&scn_phys->scn_bookmark, + ZB_DESTROYED_OBJSET, 0, 0, 0); + zfs_dbgmsg("destroying ds %llu; currently traversing; " + "reset bookmark to -1,0,0,0", + (u_longlong_t)ds->ds_object); + } + } +} + +/* + * Invoked when a dataset is destroyed. We need to make sure that: + * + * 1) If it is the dataset that was currently being scanned, we write + * a new dsl_scan_phys_t and marking the objset reference in it + * as destroyed. + * 2) Remove it from the work queue, if it was present. + * + * If the dataset was actually a snapshot, instead of marking the dataset + * as destroyed, we instead substitute the next snapshot in line. + */ +void +dsl_scan_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx) +{ + dsl_pool_t *dp = ds->ds_dir->dd_pool; + dsl_scan_t *scn = dp->dp_scan; + uint64_t mintxg; + + if (!dsl_scan_is_running(scn)) + return; + + ds_destroyed_scn_phys(ds, &scn->scn_phys); + ds_destroyed_scn_phys(ds, &scn->scn_phys_cached); + + if (scan_ds_queue_contains(scn, ds->ds_object, &mintxg)) { + scan_ds_queue_remove(scn, ds->ds_object); + if (ds->ds_is_snapshot) + scan_ds_queue_insert(scn, + dsl_dataset_phys(ds)->ds_next_snap_obj, mintxg); + } + + if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj, + ds->ds_object, &mintxg) == 0) { + ASSERT3U(dsl_dataset_phys(ds)->ds_num_children, <=, 1); + VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds->ds_object, tx)); + if (ds->ds_is_snapshot) { + /* + * We keep the same mintxg; it could be > + * ds_creation_txg if the previous snapshot was + * deleted too. + */ + VERIFY(zap_add_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, + dsl_dataset_phys(ds)->ds_next_snap_obj, + mintxg, tx) == 0); + zfs_dbgmsg("destroying ds %llu; in queue; " + "replacing with %llu", + (u_longlong_t)ds->ds_object, + (u_longlong_t)dsl_dataset_phys(ds)-> + ds_next_snap_obj); + } else { + zfs_dbgmsg("destroying ds %llu; in queue; removing", + (u_longlong_t)ds->ds_object); + } + } + + /* + * dsl_scan_sync() should be called after this, and should sync + * out our changed state, but just to be safe, do it here. + */ + dsl_scan_sync_state(scn, tx, SYNC_CACHED); +} + +static void +ds_snapshotted_bookmark(dsl_dataset_t *ds, zbookmark_phys_t *scn_bookmark) +{ + if (scn_bookmark->zb_objset == ds->ds_object) { + scn_bookmark->zb_objset = + dsl_dataset_phys(ds)->ds_prev_snap_obj; + zfs_dbgmsg("snapshotting ds %llu; currently traversing; " + "reset zb_objset to %llu", + (u_longlong_t)ds->ds_object, + (u_longlong_t)dsl_dataset_phys(ds)->ds_prev_snap_obj); + } +} + +/* + * Called when a dataset is snapshotted. If we were currently traversing + * this snapshot, we reset our bookmark to point at the newly created + * snapshot. We also modify our work queue to remove the old snapshot and + * replace with the new one. + */ +void +dsl_scan_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx) +{ + dsl_pool_t *dp = ds->ds_dir->dd_pool; + dsl_scan_t *scn = dp->dp_scan; + uint64_t mintxg; + + if (!dsl_scan_is_running(scn)) + return; + + ASSERT(dsl_dataset_phys(ds)->ds_prev_snap_obj != 0); + + ds_snapshotted_bookmark(ds, &scn->scn_phys.scn_bookmark); + ds_snapshotted_bookmark(ds, &scn->scn_phys_cached.scn_bookmark); + + if (scan_ds_queue_contains(scn, ds->ds_object, &mintxg)) { + scan_ds_queue_remove(scn, ds->ds_object); + scan_ds_queue_insert(scn, + dsl_dataset_phys(ds)->ds_prev_snap_obj, mintxg); + } + + if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj, + ds->ds_object, &mintxg) == 0) { + VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds->ds_object, tx)); + VERIFY(zap_add_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, + dsl_dataset_phys(ds)->ds_prev_snap_obj, mintxg, tx) == 0); + zfs_dbgmsg("snapshotting ds %llu; in queue; " + "replacing with %llu", + (u_longlong_t)ds->ds_object, + (u_longlong_t)dsl_dataset_phys(ds)->ds_prev_snap_obj); + } + + dsl_scan_sync_state(scn, tx, SYNC_CACHED); +} + +static void +ds_clone_swapped_bookmark(dsl_dataset_t *ds1, dsl_dataset_t *ds2, + zbookmark_phys_t *scn_bookmark) +{ + if (scn_bookmark->zb_objset == ds1->ds_object) { + scn_bookmark->zb_objset = ds2->ds_object; + zfs_dbgmsg("clone_swap ds %llu; currently traversing; " + "reset zb_objset to %llu", + (u_longlong_t)ds1->ds_object, + (u_longlong_t)ds2->ds_object); + } else if (scn_bookmark->zb_objset == ds2->ds_object) { + scn_bookmark->zb_objset = ds1->ds_object; + zfs_dbgmsg("clone_swap ds %llu; currently traversing; " + "reset zb_objset to %llu", + (u_longlong_t)ds2->ds_object, + (u_longlong_t)ds1->ds_object); + } +} + +/* + * Called when an origin dataset and its clone are swapped. If we were + * currently traversing the dataset, we need to switch to traversing the + * newly promoted clone. + */ +void +dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx) +{ + dsl_pool_t *dp = ds1->ds_dir->dd_pool; + dsl_scan_t *scn = dp->dp_scan; + uint64_t mintxg1, mintxg2; + boolean_t ds1_queued, ds2_queued; + + if (!dsl_scan_is_running(scn)) + return; + + ds_clone_swapped_bookmark(ds1, ds2, &scn->scn_phys.scn_bookmark); + ds_clone_swapped_bookmark(ds1, ds2, &scn->scn_phys_cached.scn_bookmark); + + /* + * Handle the in-memory scan queue. + */ + ds1_queued = scan_ds_queue_contains(scn, ds1->ds_object, &mintxg1); + ds2_queued = scan_ds_queue_contains(scn, ds2->ds_object, &mintxg2); + + /* Sanity checking. */ + if (ds1_queued) { + ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg); + ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg); + } + if (ds2_queued) { + ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg); + ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg); + } + + if (ds1_queued && ds2_queued) { + /* + * If both are queued, we don't need to do anything. + * The swapping code below would not handle this case correctly, + * since we can't insert ds2 if it is already there. That's + * because scan_ds_queue_insert() prohibits a duplicate insert + * and panics. + */ + } else if (ds1_queued) { + scan_ds_queue_remove(scn, ds1->ds_object); + scan_ds_queue_insert(scn, ds2->ds_object, mintxg1); + } else if (ds2_queued) { + scan_ds_queue_remove(scn, ds2->ds_object); + scan_ds_queue_insert(scn, ds1->ds_object, mintxg2); + } + + /* + * Handle the on-disk scan queue. + * The on-disk state is an out-of-date version of the in-memory state, + * so the in-memory and on-disk values for ds1_queued and ds2_queued may + * be different. Therefore we need to apply the swap logic to the + * on-disk state independently of the in-memory state. + */ + ds1_queued = zap_lookup_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds1->ds_object, &mintxg1) == 0; + ds2_queued = zap_lookup_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg2) == 0; + + /* Sanity checking. */ + if (ds1_queued) { + ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg); + ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg); + } + if (ds2_queued) { + ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg); + ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg); + } + + if (ds1_queued && ds2_queued) { + /* + * If both are queued, we don't need to do anything. + * Alternatively, we could check for EEXIST from + * zap_add_int_key() and back out to the original state, but + * that would be more work than checking for this case upfront. + */ + } else if (ds1_queued) { + VERIFY3S(0, ==, zap_remove_int(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds1->ds_object, tx)); + VERIFY3S(0, ==, zap_add_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg1, tx)); + zfs_dbgmsg("clone_swap ds %llu; in queue; " + "replacing with %llu", + (u_longlong_t)ds1->ds_object, + (u_longlong_t)ds2->ds_object); + } else if (ds2_queued) { + VERIFY3S(0, ==, zap_remove_int(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds2->ds_object, tx)); + VERIFY3S(0, ==, zap_add_int_key(dp->dp_meta_objset, + scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg2, tx)); + zfs_dbgmsg("clone_swap ds %llu; in queue; " + "replacing with %llu", + (u_longlong_t)ds2->ds_object, + (u_longlong_t)ds1->ds_object); + } + + dsl_scan_sync_state(scn, tx, SYNC_CACHED); +} + +/* ARGSUSED */ +static int +enqueue_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg) +{ + uint64_t originobj = *(uint64_t *)arg; + dsl_dataset_t *ds; + int err; + dsl_scan_t *scn = dp->dp_scan; + + if (dsl_dir_phys(hds->ds_dir)->dd_origin_obj != originobj) + return (0); + + err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds); + if (err) + return (err); + + while (dsl_dataset_phys(ds)->ds_prev_snap_obj != originobj) { + dsl_dataset_t *prev; + err = dsl_dataset_hold_obj(dp, + dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev); + + dsl_dataset_rele(ds, FTAG); + if (err) + return (err); + ds = prev; + } + scan_ds_queue_insert(scn, ds->ds_object, + dsl_dataset_phys(ds)->ds_prev_snap_txg); + dsl_dataset_rele(ds, FTAG); + return (0); +} + +static void +dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx) +{ + dsl_pool_t *dp = scn->scn_dp; + dsl_dataset_t *ds; + + VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds)); + + if (scn->scn_phys.scn_cur_min_txg >= + scn->scn_phys.scn_max_txg) { + /* + * This can happen if this snapshot was created after the + * scan started, and we already completed a previous snapshot + * that was created after the scan started. This snapshot + * only references blocks with: + * + * birth < our ds_creation_txg + * cur_min_txg is no less than ds_creation_txg. + * We have already visited these blocks. + * or + * birth > scn_max_txg + * The scan requested not to visit these blocks. + * + * Subsequent snapshots (and clones) can reference our + * blocks, or blocks with even higher birth times. + * Therefore we do not need to visit them either, + * so we do not add them to the work queue. + * + * Note that checking for cur_min_txg >= cur_max_txg + * is not sufficient, because in that case we may need to + * visit subsequent snapshots. This happens when min_txg > 0, + * which raises cur_min_txg. In this case we will visit + * this dataset but skip all of its blocks, because the + * rootbp's birth time is < cur_min_txg. Then we will + * add the next snapshots/clones to the work queue. + */ + char *dsname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); + dsl_dataset_name(ds, dsname); + zfs_dbgmsg("scanning dataset %llu (%s) is unnecessary because " + "cur_min_txg (%llu) >= max_txg (%llu)", + (longlong_t)dsobj, dsname, + (longlong_t)scn->scn_phys.scn_cur_min_txg, + (longlong_t)scn->scn_phys.scn_max_txg); + kmem_free(dsname, MAXNAMELEN); + + goto out; + } + + /* + * Only the ZIL in the head (non-snapshot) is valid. Even though + * snapshots can have ZIL block pointers (which may be the same + * BP as in the head), they must be ignored. In addition, $ORIGIN + * doesn't have a objset (i.e. its ds_bp is a hole) so we don't + * need to look for a ZIL in it either. So we traverse the ZIL here, + * rather than in scan_recurse(), because the regular snapshot + * block-sharing rules don't apply to it. + */ + if (!dsl_dataset_is_snapshot(ds) && + (dp->dp_origin_snap == NULL || + ds->ds_dir != dp->dp_origin_snap->ds_dir)) { + objset_t *os; + if (dmu_objset_from_ds(ds, &os) != 0) { + goto out; + } + dsl_scan_zil(dp, &os->os_zil_header); + } + + /* + * Iterate over the bps in this ds. + */ + dmu_buf_will_dirty(ds->ds_dbuf, tx); + rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG); + dsl_scan_visit_rootbp(scn, ds, &dsl_dataset_phys(ds)->ds_bp, tx); + rrw_exit(&ds->ds_bp_rwlock, FTAG); + + char *dsname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); + dsl_dataset_name(ds, dsname); + zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; " + "suspending=%u", + (longlong_t)dsobj, dsname, + (longlong_t)scn->scn_phys.scn_cur_min_txg, + (longlong_t)scn->scn_phys.scn_cur_max_txg, + (int)scn->scn_suspending); + kmem_free(dsname, ZFS_MAX_DATASET_NAME_LEN); + + if (scn->scn_suspending) + goto out; + + /* + * We've finished this pass over this dataset. + */ + + /* + * If we did not completely visit this dataset, do another pass. + */ + if (scn->scn_phys.scn_flags & DSF_VISIT_DS_AGAIN) { + zfs_dbgmsg("incomplete pass; visiting again"); + scn->scn_phys.scn_flags &= ~DSF_VISIT_DS_AGAIN; + scan_ds_queue_insert(scn, ds->ds_object, + scn->scn_phys.scn_cur_max_txg); + goto out; + } + + /* + * Add descendant datasets to work queue. + */ + if (dsl_dataset_phys(ds)->ds_next_snap_obj != 0) { + scan_ds_queue_insert(scn, + dsl_dataset_phys(ds)->ds_next_snap_obj, + dsl_dataset_phys(ds)->ds_creation_txg); + } + if (dsl_dataset_phys(ds)->ds_num_children > 1) { + boolean_t usenext = B_FALSE; + if (dsl_dataset_phys(ds)->ds_next_clones_obj != 0) { + uint64_t count; + /* + * A bug in a previous version of the code could + * cause upgrade_clones_cb() to not set + * ds_next_snap_obj when it should, leading to a + * missing entry. Therefore we can only use the + * next_clones_obj when its count is correct. + */ + int err = zap_count(dp->dp_meta_objset, + dsl_dataset_phys(ds)->ds_next_clones_obj, &count); + if (err == 0 && + count == dsl_dataset_phys(ds)->ds_num_children - 1) + usenext = B_TRUE; + } + + if (usenext) { + zap_cursor_t zc; + zap_attribute_t za; + for (zap_cursor_init(&zc, dp->dp_meta_objset, + dsl_dataset_phys(ds)->ds_next_clones_obj); + zap_cursor_retrieve(&zc, &za) == 0; + (void) zap_cursor_advance(&zc)) { + scan_ds_queue_insert(scn, + zfs_strtonum(za.za_name, NULL), + dsl_dataset_phys(ds)->ds_creation_txg); + } + zap_cursor_fini(&zc); + } else { + VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, + enqueue_clones_cb, &ds->ds_object, + DS_FIND_CHILDREN)); + } + } + +out: + dsl_dataset_rele(ds, FTAG); +} + +/* ARGSUSED */ +static int +enqueue_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg) +{ + dsl_dataset_t *ds; + int err; + dsl_scan_t *scn = dp->dp_scan; + + err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds); + if (err) + return (err); + + while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) { + dsl_dataset_t *prev; + err = dsl_dataset_hold_obj(dp, + dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev); + if (err) { + dsl_dataset_rele(ds, FTAG); + return (err); + } + + /* + * If this is a clone, we don't need to worry about it for now. + */ + if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object) { + dsl_dataset_rele(ds, FTAG); + dsl_dataset_rele(prev, FTAG); + return (0); + } + dsl_dataset_rele(ds, FTAG); + ds = prev; + } + + scan_ds_queue_insert(scn, ds->ds_object, + dsl_dataset_phys(ds)->ds_prev_snap_txg); + dsl_dataset_rele(ds, FTAG); + return (0); +} + +/* ARGSUSED */ +void +dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum, + ddt_entry_t *dde, dmu_tx_t *tx) +{ + const ddt_key_t *ddk = &dde->dde_key; + ddt_phys_t *ddp = dde->dde_phys; + blkptr_t bp; + zbookmark_phys_t zb = { 0 }; + int p; + + if (!dsl_scan_is_running(scn)) + return; + + /* + * This function is special because it is the only thing + * that can add scan_io_t's to the vdev scan queues from + * outside dsl_scan_sync(). For the most part this is ok + * as long as it is called from within syncing context. + * However, dsl_scan_sync() expects that no new sio's will + * be added between when all the work for a scan is done + * and the next txg when the scan is actually marked as + * completed. This check ensures we do not issue new sio's + * during this period. + */ + if (scn->scn_done_txg != 0) + return; + + for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++) { + if (ddp->ddp_phys_birth == 0 || + ddp->ddp_phys_birth > scn->scn_phys.scn_max_txg) + continue; + ddt_bp_create(checksum, ddk, ddp, &bp); + + scn->scn_visited_this_txg++; + scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb); + } +} + +/* + * Scrub/dedup interaction. + * + * If there are N references to a deduped block, we don't want to scrub it + * N times -- ideally, we should scrub it exactly once. + * + * We leverage the fact that the dde's replication class (enum ddt_class) + * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest + * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order. + * + * To prevent excess scrubbing, the scrub begins by walking the DDT + * to find all blocks with refcnt > 1, and scrubs each of these once. + * Since there are two replication classes which contain blocks with + * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first. + * Finally the top-down scrub begins, only visiting blocks with refcnt == 1. + * + * There would be nothing more to say if a block's refcnt couldn't change + * during a scrub, but of course it can so we must account for changes + * in a block's replication class. + * + * Here's an example of what can occur: + * + * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1 + * when visited during the top-down scrub phase, it will be scrubbed twice. + * This negates our scrub optimization, but is otherwise harmless. + * + * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1 + * on each visit during the top-down scrub phase, it will never be scrubbed. + * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's + * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to + * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1 + * while a scrub is in progress, it scrubs the block right then. + */ +static void +dsl_scan_ddt(dsl_scan_t *scn, dmu_tx_t *tx) +{ + ddt_bookmark_t *ddb = &scn->scn_phys.scn_ddt_bookmark; + ddt_entry_t dde; + int error; + uint64_t n = 0; + + bzero(&dde, sizeof (ddt_entry_t)); + + while ((error = ddt_walk(scn->scn_dp->dp_spa, ddb, &dde)) == 0) { + ddt_t *ddt; + + if (ddb->ddb_class > scn->scn_phys.scn_ddt_class_max) + break; + dprintf("visiting ddb=%llu/%llu/%llu/%llx\n", + (longlong_t)ddb->ddb_class, + (longlong_t)ddb->ddb_type, + (longlong_t)ddb->ddb_checksum, + (longlong_t)ddb->ddb_cursor); + + /* There should be no pending changes to the dedup table */ + ddt = scn->scn_dp->dp_spa->spa_ddt[ddb->ddb_checksum]; + ASSERT(avl_first(&ddt->ddt_tree) == NULL); + + dsl_scan_ddt_entry(scn, ddb->ddb_checksum, &dde, tx); + n++; + + if (dsl_scan_check_suspend(scn, NULL)) + break; + } + + zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; " + "suspending=%u", (longlong_t)n, + (int)scn->scn_phys.scn_ddt_class_max, (int)scn->scn_suspending); + + ASSERT(error == 0 || error == ENOENT); + ASSERT(error != ENOENT || + ddb->ddb_class > scn->scn_phys.scn_ddt_class_max); +} + +static uint64_t +dsl_scan_ds_maxtxg(dsl_dataset_t *ds) +{ + uint64_t smt = ds->ds_dir->dd_pool->dp_scan->scn_phys.scn_max_txg; + if (ds->ds_is_snapshot) + return (MIN(smt, dsl_dataset_phys(ds)->ds_creation_txg)); + return (smt); +} + +static void +dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx) +{ + scan_ds_t *sds; + dsl_pool_t *dp = scn->scn_dp; + + if (scn->scn_phys.scn_ddt_bookmark.ddb_class <= + scn->scn_phys.scn_ddt_class_max) { + scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg; + scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg; + dsl_scan_ddt(scn, tx); + if (scn->scn_suspending) + return; + } + + if (scn->scn_phys.scn_bookmark.zb_objset == DMU_META_OBJSET) { + /* First do the MOS & ORIGIN */ + + scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg; + scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg; + dsl_scan_visit_rootbp(scn, NULL, + &dp->dp_meta_rootbp, tx); + spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp); + if (scn->scn_suspending) + return; + + if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) { + VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, + enqueue_cb, NULL, DS_FIND_CHILDREN)); + } else { + dsl_scan_visitds(scn, + dp->dp_origin_snap->ds_object, tx); + } + ASSERT(!scn->scn_suspending); + } else if (scn->scn_phys.scn_bookmark.zb_objset != + ZB_DESTROYED_OBJSET) { + uint64_t dsobj = scn->scn_phys.scn_bookmark.zb_objset; + /* + * If we were suspended, continue from here. Note if the + * ds we were suspended on was deleted, the zb_objset may + * be -1, so we will skip this and find a new objset + * below. + */ + dsl_scan_visitds(scn, dsobj, tx); + if (scn->scn_suspending) + return; + } + + /* + * In case we suspended right at the end of the ds, zero the + * bookmark so we don't think that we're still trying to resume. + */ + bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_phys_t)); + + /* + * Keep pulling things out of the dataset avl queue. Updates to the + * persistent zap-object-as-queue happen only at checkpoints. + */ + while ((sds = avl_first(&scn->scn_queue)) != NULL) { + dsl_dataset_t *ds; + uint64_t dsobj = sds->sds_dsobj; + uint64_t txg = sds->sds_txg; + + /* dequeue and free the ds from the queue */ + scan_ds_queue_remove(scn, dsobj); + sds = NULL; + + /* set up min / max txg */ + VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds)); + if (txg != 0) { + scn->scn_phys.scn_cur_min_txg = + MAX(scn->scn_phys.scn_min_txg, txg); + } else { + scn->scn_phys.scn_cur_min_txg = + MAX(scn->scn_phys.scn_min_txg, + dsl_dataset_phys(ds)->ds_prev_snap_txg); + } + scn->scn_phys.scn_cur_max_txg = dsl_scan_ds_maxtxg(ds); + dsl_dataset_rele(ds, FTAG); + + dsl_scan_visitds(scn, dsobj, tx); + if (scn->scn_suspending) + return; + } + + /* No more objsets to fetch, we're done */ + scn->scn_phys.scn_bookmark.zb_objset = ZB_DESTROYED_OBJSET; + ASSERT0(scn->scn_suspending); +} + +static uint64_t +dsl_scan_count_leaves(vdev_t *vd) +{ + uint64_t i, leaves = 0; + + /* we only count leaves that belong to the main pool and are readable */ + if (vd->vdev_islog || vd->vdev_isspare || + vd->vdev_isl2cache || !vdev_readable(vd)) + return (0); + + if (vd->vdev_ops->vdev_op_leaf) + return (1); + + for (i = 0; i < vd->vdev_children; i++) { + leaves += dsl_scan_count_leaves(vd->vdev_child[i]); + } + + return (leaves); +} + +static void +scan_io_queues_update_zio_stats(dsl_scan_io_queue_t *q, const blkptr_t *bp) +{ + int i; + uint64_t cur_size = 0; + + for (i = 0; i < BP_GET_NDVAS(bp); i++) { + cur_size += DVA_GET_ASIZE(&bp->blk_dva[i]); + } + + q->q_total_zio_size_this_txg += cur_size; + q->q_zios_this_txg++; +} + +static void +scan_io_queues_update_seg_stats(dsl_scan_io_queue_t *q, uint64_t start, + uint64_t end) +{ + q->q_total_seg_size_this_txg += end - start; + q->q_segs_this_txg++; +} + +static boolean_t +scan_io_queue_check_suspend(dsl_scan_t *scn) +{ + /* See comment in dsl_scan_check_suspend() */ + uint64_t curr_time_ns = gethrtime(); + uint64_t scan_time_ns = curr_time_ns - scn->scn_sync_start_time; + uint64_t sync_time_ns = curr_time_ns - + scn->scn_dp->dp_spa->spa_sync_starttime; + int dirty_pct = scn->scn_dp->dp_dirty_total * 100 / zfs_dirty_data_max; + int mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ? + zfs_resilver_min_time_ms : zfs_scrub_min_time_ms; + + return ((NSEC2MSEC(scan_time_ns) > mintime && + (dirty_pct >= zfs_vdev_async_write_active_min_dirty_percent || + txg_sync_waiting(scn->scn_dp) || + NSEC2SEC(sync_time_ns) >= zfs_txg_timeout)) || + spa_shutting_down(scn->scn_dp->dp_spa)); +} + +/* + * Given a list of scan_io_t's in io_list, this issues the I/Os out to + * disk. This consumes the io_list and frees the scan_io_t's. This is + * called when emptying queues, either when we're up against the memory + * limit or when we have finished scanning. Returns B_TRUE if we stopped + * processing the list before we finished. Any sios that were not issued + * will remain in the io_list. + */ +static boolean_t +scan_io_queue_issue(dsl_scan_io_queue_t *queue, list_t *io_list) +{ + dsl_scan_t *scn = queue->q_scn; + scan_io_t *sio; + int64_t bytes_issued = 0; + boolean_t suspended = B_FALSE; + + while ((sio = list_head(io_list)) != NULL) { + blkptr_t bp; + + if (scan_io_queue_check_suspend(scn)) { + suspended = B_TRUE; + break; + } + + sio2bp(sio, &bp); + bytes_issued += SIO_GET_ASIZE(sio); + scan_exec_io(scn->scn_dp, &bp, sio->sio_flags, + &sio->sio_zb, queue); + (void) list_remove_head(io_list); + scan_io_queues_update_zio_stats(queue, &bp); + sio_free(sio); + } + + atomic_add_64(&scn->scn_bytes_pending, -bytes_issued); + + return (suspended); +} + +/* + * This function removes sios from an IO queue which reside within a given + * range_seg_t and inserts them (in offset order) into a list. Note that + * we only ever return a maximum of 32 sios at once. If there are more sios + * to process within this segment that did not make it onto the list we + * return B_TRUE and otherwise B_FALSE. + */ +static boolean_t +scan_io_queue_gather(dsl_scan_io_queue_t *queue, range_seg_t *rs, list_t *list) +{ + scan_io_t *srch_sio, *sio, *next_sio; + avl_index_t idx; + uint_t num_sios = 0; + int64_t bytes_issued = 0; + + ASSERT(rs != NULL); + ASSERT(MUTEX_HELD(&queue->q_vd->vdev_scan_io_queue_lock)); + + srch_sio = sio_alloc(1); + srch_sio->sio_nr_dvas = 1; + SIO_SET_OFFSET(srch_sio, rs_get_start(rs, queue->q_exts_by_addr)); + + /* + * The exact start of the extent might not contain any matching zios, + * so if that's the case, examine the next one in the tree. + */ + sio = avl_find(&queue->q_sios_by_addr, srch_sio, &idx); + sio_free(srch_sio); + + if (sio == NULL) + sio = avl_nearest(&queue->q_sios_by_addr, idx, AVL_AFTER); + + while (sio != NULL && SIO_GET_OFFSET(sio) < rs_get_end(rs, + queue->q_exts_by_addr) && num_sios <= 32) { + ASSERT3U(SIO_GET_OFFSET(sio), >=, rs_get_start(rs, + queue->q_exts_by_addr)); + ASSERT3U(SIO_GET_END_OFFSET(sio), <=, rs_get_end(rs, + queue->q_exts_by_addr)); + + next_sio = AVL_NEXT(&queue->q_sios_by_addr, sio); + avl_remove(&queue->q_sios_by_addr, sio); + queue->q_sio_memused -= SIO_GET_MUSED(sio); + + bytes_issued += SIO_GET_ASIZE(sio); + num_sios++; + list_insert_tail(list, sio); + sio = next_sio; + } + + /* + * We limit the number of sios we process at once to 32 to avoid + * biting off more than we can chew. If we didn't take everything + * in the segment we update it to reflect the work we were able to + * complete. Otherwise, we remove it from the range tree entirely. + */ + if (sio != NULL && SIO_GET_OFFSET(sio) < rs_get_end(rs, + queue->q_exts_by_addr)) { + range_tree_adjust_fill(queue->q_exts_by_addr, rs, + -bytes_issued); + range_tree_resize_segment(queue->q_exts_by_addr, rs, + SIO_GET_OFFSET(sio), rs_get_end(rs, + queue->q_exts_by_addr) - SIO_GET_OFFSET(sio)); + + return (B_TRUE); + } else { + uint64_t rstart = rs_get_start(rs, queue->q_exts_by_addr); + uint64_t rend = rs_get_end(rs, queue->q_exts_by_addr); + range_tree_remove(queue->q_exts_by_addr, rstart, rend - rstart); + return (B_FALSE); + } +} + +/* + * This is called from the queue emptying thread and selects the next + * extent from which we are to issue I/Os. The behavior of this function + * depends on the state of the scan, the current memory consumption and + * whether or not we are performing a scan shutdown. + * 1) We select extents in an elevator algorithm (LBA-order) if the scan + * needs to perform a checkpoint + * 2) We select the largest available extent if we are up against the + * memory limit. + * 3) Otherwise we don't select any extents. + */ +static range_seg_t * +scan_io_queue_fetch_ext(dsl_scan_io_queue_t *queue) +{ + dsl_scan_t *scn = queue->q_scn; + range_tree_t *rt = queue->q_exts_by_addr; + + ASSERT(MUTEX_HELD(&queue->q_vd->vdev_scan_io_queue_lock)); + ASSERT(scn->scn_is_sorted); + + /* handle tunable overrides */ + if (scn->scn_checkpointing || scn->scn_clearing) { + if (zfs_scan_issue_strategy == 1) { + return (range_tree_first(rt)); + } else if (zfs_scan_issue_strategy == 2) { + /* + * We need to get the original entry in the by_addr + * tree so we can modify it. + */ + range_seg_t *size_rs = + zfs_btree_first(&queue->q_exts_by_size, NULL); + if (size_rs == NULL) + return (NULL); + uint64_t start = rs_get_start(size_rs, rt); + uint64_t size = rs_get_end(size_rs, rt) - start; + range_seg_t *addr_rs = range_tree_find(rt, start, + size); + ASSERT3P(addr_rs, !=, NULL); + ASSERT3U(rs_get_start(size_rs, rt), ==, + rs_get_start(addr_rs, rt)); + ASSERT3U(rs_get_end(size_rs, rt), ==, + rs_get_end(addr_rs, rt)); + return (addr_rs); + } + } + + /* + * During normal clearing, we want to issue our largest segments + * first, keeping IO as sequential as possible, and leaving the + * smaller extents for later with the hope that they might eventually + * grow to larger sequential segments. However, when the scan is + * checkpointing, no new extents will be added to the sorting queue, + * so the way we are sorted now is as good as it will ever get. + * In this case, we instead switch to issuing extents in LBA order. + */ + if (scn->scn_checkpointing) { + return (range_tree_first(rt)); + } else if (scn->scn_clearing) { + /* + * We need to get the original entry in the by_addr + * tree so we can modify it. + */ + range_seg_t *size_rs = zfs_btree_first(&queue->q_exts_by_size, + NULL); + if (size_rs == NULL) + return (NULL); + uint64_t start = rs_get_start(size_rs, rt); + uint64_t size = rs_get_end(size_rs, rt) - start; + range_seg_t *addr_rs = range_tree_find(rt, start, size); + ASSERT3P(addr_rs, !=, NULL); + ASSERT3U(rs_get_start(size_rs, rt), ==, rs_get_start(addr_rs, + rt)); + ASSERT3U(rs_get_end(size_rs, rt), ==, rs_get_end(addr_rs, rt)); + return (addr_rs); + } else { + return (NULL); + } +} + +static void +scan_io_queues_run_one(void *arg) +{ + dsl_scan_io_queue_t *queue = arg; + kmutex_t *q_lock = &queue->q_vd->vdev_scan_io_queue_lock; + boolean_t suspended = B_FALSE; + range_seg_t *rs = NULL; + scan_io_t *sio = NULL; + list_t sio_list; + uint64_t bytes_per_leaf = zfs_scan_vdev_limit; + uint64_t nr_leaves = dsl_scan_count_leaves(queue->q_vd); + + ASSERT(queue->q_scn->scn_is_sorted); + + list_create(&sio_list, sizeof (scan_io_t), + offsetof(scan_io_t, sio_nodes.sio_list_node)); + mutex_enter(q_lock); + + /* calculate maximum in-flight bytes for this txg (min 1MB) */ + queue->q_maxinflight_bytes = + MAX(nr_leaves * bytes_per_leaf, 1ULL << 20); + + /* reset per-queue scan statistics for this txg */ + queue->q_total_seg_size_this_txg = 0; + queue->q_segs_this_txg = 0; + queue->q_total_zio_size_this_txg = 0; + queue->q_zios_this_txg = 0; + + /* loop until we run out of time or sios */ + while ((rs = scan_io_queue_fetch_ext(queue)) != NULL) { + uint64_t seg_start = 0, seg_end = 0; + boolean_t more_left = B_TRUE; + + ASSERT(list_is_empty(&sio_list)); + + /* loop while we still have sios left to process in this rs */ + while (more_left) { + scan_io_t *first_sio, *last_sio; + + /* + * We have selected which extent needs to be + * processed next. Gather up the corresponding sios. + */ + more_left = scan_io_queue_gather(queue, rs, &sio_list); + ASSERT(!list_is_empty(&sio_list)); + first_sio = list_head(&sio_list); + last_sio = list_tail(&sio_list); + + seg_end = SIO_GET_END_OFFSET(last_sio); + if (seg_start == 0) + seg_start = SIO_GET_OFFSET(first_sio); + + /* + * Issuing sios can take a long time so drop the + * queue lock. The sio queue won't be updated by + * other threads since we're in syncing context so + * we can be sure that our trees will remain exactly + * as we left them. + */ + mutex_exit(q_lock); + suspended = scan_io_queue_issue(queue, &sio_list); + mutex_enter(q_lock); + + if (suspended) + break; + } + + /* update statistics for debugging purposes */ + scan_io_queues_update_seg_stats(queue, seg_start, seg_end); + + if (suspended) + break; + } + + /* + * If we were suspended in the middle of processing, + * requeue any unfinished sios and exit. + */ + while ((sio = list_head(&sio_list)) != NULL) { + list_remove(&sio_list, sio); + scan_io_queue_insert_impl(queue, sio); + } + + mutex_exit(q_lock); + list_destroy(&sio_list); +} + +/* + * Performs an emptying run on all scan queues in the pool. This just + * punches out one thread per top-level vdev, each of which processes + * only that vdev's scan queue. We can parallelize the I/O here because + * we know that each queue's I/Os only affect its own top-level vdev. + * + * This function waits for the queue runs to complete, and must be + * called from dsl_scan_sync (or in general, syncing context). + */ +static void +scan_io_queues_run(dsl_scan_t *scn) +{ + spa_t *spa = scn->scn_dp->dp_spa; + + ASSERT(scn->scn_is_sorted); + ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER)); + + if (scn->scn_bytes_pending == 0) + return; + + if (scn->scn_taskq == NULL) { + int nthreads = spa->spa_root_vdev->vdev_children; + + /* + * We need to make this taskq *always* execute as many + * threads in parallel as we have top-level vdevs and no + * less, otherwise strange serialization of the calls to + * scan_io_queues_run_one can occur during spa_sync runs + * and that significantly impacts performance. + */ + scn->scn_taskq = taskq_create("dsl_scan_iss", nthreads, + minclsyspri, nthreads, nthreads, TASKQ_PREPOPULATE); + } + + for (uint64_t i = 0; i < spa->spa_root_vdev->vdev_children; i++) { + vdev_t *vd = spa->spa_root_vdev->vdev_child[i]; + + mutex_enter(&vd->vdev_scan_io_queue_lock); + if (vd->vdev_scan_io_queue != NULL) { + VERIFY(taskq_dispatch(scn->scn_taskq, + scan_io_queues_run_one, vd->vdev_scan_io_queue, + TQ_SLEEP) != TASKQID_INVALID); + } + mutex_exit(&vd->vdev_scan_io_queue_lock); + } + + /* + * Wait for the queues to finish issuing their IOs for this run + * before we return. There may still be IOs in flight at this + * point. + */ + taskq_wait(scn->scn_taskq); +} + +static boolean_t +dsl_scan_async_block_should_pause(dsl_scan_t *scn) +{ + uint64_t elapsed_nanosecs; + + if (zfs_recover) + return (B_FALSE); + + if (zfs_async_block_max_blocks != 0 && + scn->scn_visited_this_txg >= zfs_async_block_max_blocks) { + return (B_TRUE); + } + + if (zfs_max_async_dedup_frees != 0 && + scn->scn_dedup_frees_this_txg >= zfs_max_async_dedup_frees) { + return (B_TRUE); + } + + elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time; + return (elapsed_nanosecs / NANOSEC > zfs_txg_timeout || + (NSEC2MSEC(elapsed_nanosecs) > scn->scn_async_block_min_time_ms && + txg_sync_waiting(scn->scn_dp)) || + spa_shutting_down(scn->scn_dp->dp_spa)); +} + +static int +dsl_scan_free_block_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx) +{ + dsl_scan_t *scn = arg; + + if (!scn->scn_is_bptree || + (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)) { + if (dsl_scan_async_block_should_pause(scn)) + return (SET_ERROR(ERESTART)); + } + + zio_nowait(zio_free_sync(scn->scn_zio_root, scn->scn_dp->dp_spa, + dmu_tx_get_txg(tx), bp, 0)); + dsl_dir_diduse_space(tx->tx_pool->dp_free_dir, DD_USED_HEAD, + -bp_get_dsize_sync(scn->scn_dp->dp_spa, bp), + -BP_GET_PSIZE(bp), -BP_GET_UCSIZE(bp), tx); + scn->scn_visited_this_txg++; + if (BP_GET_DEDUP(bp)) + scn->scn_dedup_frees_this_txg++; + return (0); +} + +static void +dsl_scan_update_stats(dsl_scan_t *scn) +{ + spa_t *spa = scn->scn_dp->dp_spa; + uint64_t i; + uint64_t seg_size_total = 0, zio_size_total = 0; + uint64_t seg_count_total = 0, zio_count_total = 0; + + for (i = 0; i < spa->spa_root_vdev->vdev_children; i++) { + vdev_t *vd = spa->spa_root_vdev->vdev_child[i]; + dsl_scan_io_queue_t *queue = vd->vdev_scan_io_queue; + + if (queue == NULL) + continue; + + seg_size_total += queue->q_total_seg_size_this_txg; + zio_size_total += queue->q_total_zio_size_this_txg; + seg_count_total += queue->q_segs_this_txg; + zio_count_total += queue->q_zios_this_txg; + } + + if (seg_count_total == 0 || zio_count_total == 0) { + scn->scn_avg_seg_size_this_txg = 0; + scn->scn_avg_zio_size_this_txg = 0; + scn->scn_segs_this_txg = 0; + scn->scn_zios_this_txg = 0; + return; + } + + scn->scn_avg_seg_size_this_txg = seg_size_total / seg_count_total; + scn->scn_avg_zio_size_this_txg = zio_size_total / zio_count_total; + scn->scn_segs_this_txg = seg_count_total; + scn->scn_zios_this_txg = zio_count_total; +} + +static int +bpobj_dsl_scan_free_block_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed, + dmu_tx_t *tx) +{ + ASSERT(!bp_freed); + return (dsl_scan_free_block_cb(arg, bp, tx)); +} + +static int +dsl_scan_obsolete_block_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed, + dmu_tx_t *tx) +{ + ASSERT(!bp_freed); + dsl_scan_t *scn = arg; + const dva_t *dva = &bp->blk_dva[0]; + + if (dsl_scan_async_block_should_pause(scn)) + return (SET_ERROR(ERESTART)); + + spa_vdev_indirect_mark_obsolete(scn->scn_dp->dp_spa, + DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), + DVA_GET_ASIZE(dva), tx); + scn->scn_visited_this_txg++; + return (0); +} + +boolean_t +dsl_scan_active(dsl_scan_t *scn) +{ + spa_t *spa = scn->scn_dp->dp_spa; + uint64_t used = 0, comp, uncomp; + boolean_t clones_left; + + if (spa->spa_load_state != SPA_LOAD_NONE) + return (B_FALSE); + if (spa_shutting_down(spa)) + return (B_FALSE); + if ((dsl_scan_is_running(scn) && !dsl_scan_is_paused_scrub(scn)) || + (scn->scn_async_destroying && !scn->scn_async_stalled)) + return (B_TRUE); + + if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) { + (void) bpobj_space(&scn->scn_dp->dp_free_bpobj, + &used, &comp, &uncomp); + } + clones_left = spa_livelist_delete_check(spa); + return ((used != 0) || (clones_left)); +} + +static boolean_t +dsl_scan_check_deferred(vdev_t *vd) +{ + boolean_t need_resilver = B_FALSE; + + for (int c = 0; c < vd->vdev_children; c++) { + need_resilver |= + dsl_scan_check_deferred(vd->vdev_child[c]); + } + + if (!vdev_is_concrete(vd) || vd->vdev_aux || + !vd->vdev_ops->vdev_op_leaf) + return (need_resilver); + + if (!vd->vdev_resilver_deferred) + need_resilver = B_TRUE; + + return (need_resilver); +} + +static boolean_t +dsl_scan_need_resilver(spa_t *spa, const dva_t *dva, size_t psize, + uint64_t phys_birth) +{ + vdev_t *vd; + + vd = vdev_lookup_top(spa, DVA_GET_VDEV(dva)); + + if (vd->vdev_ops == &vdev_indirect_ops) { + /* + * The indirect vdev can point to multiple + * vdevs. For simplicity, always create + * the resilver zio_t. zio_vdev_io_start() + * will bypass the child resilver i/o's if + * they are on vdevs that don't have DTL's. + */ + return (B_TRUE); + } + + if (DVA_GET_GANG(dva)) { + /* + * Gang members may be spread across multiple + * vdevs, so the best estimate we have is the + * scrub range, which has already been checked. + * XXX -- it would be better to change our + * allocation policy to ensure that all + * gang members reside on the same vdev. + */ + return (B_TRUE); + } + + /* + * Check if the txg falls within the range which must be + * resilvered. DVAs outside this range can always be skipped. + */ + if (!vdev_dtl_contains(vd, DTL_PARTIAL, phys_birth, 1)) + return (B_FALSE); + + /* + * Check if the top-level vdev must resilver this offset. + * When the offset does not intersect with a dirty leaf DTL + * then it may be possible to skip the resilver IO. The psize + * is provided instead of asize to simplify the check for RAIDZ. + */ + if (!vdev_dtl_need_resilver(vd, DVA_GET_OFFSET(dva), psize)) + return (B_FALSE); + + /* + * Check that this top-level vdev has a device under it which + * is resilvering and is not deferred. + */ + if (!dsl_scan_check_deferred(vd)) + return (B_FALSE); + + return (B_TRUE); +} + +static int +dsl_process_async_destroys(dsl_pool_t *dp, dmu_tx_t *tx) +{ + dsl_scan_t *scn = dp->dp_scan; + spa_t *spa = dp->dp_spa; + int err = 0; + + if (spa_suspend_async_destroy(spa)) + return (0); + + if (zfs_free_bpobj_enabled && + spa_version(spa) >= SPA_VERSION_DEADLISTS) { + scn->scn_is_bptree = B_FALSE; + scn->scn_async_block_min_time_ms = zfs_free_min_time_ms; + scn->scn_zio_root = zio_root(spa, NULL, + NULL, ZIO_FLAG_MUSTSUCCEED); + err = bpobj_iterate(&dp->dp_free_bpobj, + bpobj_dsl_scan_free_block_cb, scn, tx); + VERIFY0(zio_wait(scn->scn_zio_root)); + scn->scn_zio_root = NULL; + + if (err != 0 && err != ERESTART) + zfs_panic_recover("error %u from bpobj_iterate()", err); + } + + if (err == 0 && spa_feature_is_active(spa, SPA_FEATURE_ASYNC_DESTROY)) { + ASSERT(scn->scn_async_destroying); + scn->scn_is_bptree = B_TRUE; + scn->scn_zio_root = zio_root(spa, NULL, + NULL, ZIO_FLAG_MUSTSUCCEED); + err = bptree_iterate(dp->dp_meta_objset, + dp->dp_bptree_obj, B_TRUE, dsl_scan_free_block_cb, scn, tx); + VERIFY0(zio_wait(scn->scn_zio_root)); + scn->scn_zio_root = NULL; + + if (err == EIO || err == ECKSUM) { + err = 0; + } else if (err != 0 && err != ERESTART) { + zfs_panic_recover("error %u from " + "traverse_dataset_destroyed()", err); + } + + if (bptree_is_empty(dp->dp_meta_objset, dp->dp_bptree_obj)) { + /* finished; deactivate async destroy feature */ + spa_feature_decr(spa, SPA_FEATURE_ASYNC_DESTROY, tx); + ASSERT(!spa_feature_is_active(spa, + SPA_FEATURE_ASYNC_DESTROY)); + VERIFY0(zap_remove(dp->dp_meta_objset, + DMU_POOL_DIRECTORY_OBJECT, + DMU_POOL_BPTREE_OBJ, tx)); + VERIFY0(bptree_free(dp->dp_meta_objset, + dp->dp_bptree_obj, tx)); + dp->dp_bptree_obj = 0; + scn->scn_async_destroying = B_FALSE; + scn->scn_async_stalled = B_FALSE; + } else { + /* + * If we didn't make progress, mark the async + * destroy as stalled, so that we will not initiate + * a spa_sync() on its behalf. Note that we only + * check this if we are not finished, because if the + * bptree had no blocks for us to visit, we can + * finish without "making progress". + */ + scn->scn_async_stalled = + (scn->scn_visited_this_txg == 0); + } + } + if (scn->scn_visited_this_txg) { + zfs_dbgmsg("freed %llu blocks in %llums from " + "free_bpobj/bptree txg %llu; err=%u", + (longlong_t)scn->scn_visited_this_txg, + (longlong_t) + NSEC2MSEC(gethrtime() - scn->scn_sync_start_time), + (longlong_t)tx->tx_txg, err); + scn->scn_visited_this_txg = 0; + scn->scn_dedup_frees_this_txg = 0; + + /* + * Write out changes to the DDT that may be required as a + * result of the blocks freed. This ensures that the DDT + * is clean when a scrub/resilver runs. + */ + ddt_sync(spa, tx->tx_txg); + } + if (err != 0) + return (err); + if (dp->dp_free_dir != NULL && !scn->scn_async_destroying && + zfs_free_leak_on_eio && + (dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes != 0 || + dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes != 0 || + dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes != 0)) { + /* + * We have finished background destroying, but there is still + * some space left in the dp_free_dir. Transfer this leaked + * space to the dp_leak_dir. + */ + if (dp->dp_leak_dir == NULL) { + rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG); + (void) dsl_dir_create_sync(dp, dp->dp_root_dir, + LEAK_DIR_NAME, tx); + VERIFY0(dsl_pool_open_special_dir(dp, + LEAK_DIR_NAME, &dp->dp_leak_dir)); + rrw_exit(&dp->dp_config_rwlock, FTAG); + } + dsl_dir_diduse_space(dp->dp_leak_dir, DD_USED_HEAD, + dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes, + dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes, + dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes, tx); + dsl_dir_diduse_space(dp->dp_free_dir, DD_USED_HEAD, + -dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes, + -dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes, + -dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes, tx); + } + + if (dp->dp_free_dir != NULL && !scn->scn_async_destroying && + !spa_livelist_delete_check(spa)) { + /* finished; verify that space accounting went to zero */ + ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes); + ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes); + ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes); + } + + spa_notify_waiters(spa); + + EQUIV(bpobj_is_open(&dp->dp_obsolete_bpobj), + 0 == zap_contains(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT, + DMU_POOL_OBSOLETE_BPOBJ)); + if (err == 0 && bpobj_is_open(&dp->dp_obsolete_bpobj)) { + ASSERT(spa_feature_is_active(dp->dp_spa, + SPA_FEATURE_OBSOLETE_COUNTS)); + + scn->scn_is_bptree = B_FALSE; + scn->scn_async_block_min_time_ms = zfs_obsolete_min_time_ms; + err = bpobj_iterate(&dp->dp_obsolete_bpobj, + dsl_scan_obsolete_block_cb, scn, tx); + if (err != 0 && err != ERESTART) + zfs_panic_recover("error %u from bpobj_iterate()", err); + + if (bpobj_is_empty(&dp->dp_obsolete_bpobj)) + dsl_pool_destroy_obsolete_bpobj(dp, tx); + } + return (0); +} + +/* + * This is the primary entry point for scans that is called from syncing + * context. Scans must happen entirely during syncing context so that we + * can guarantee that blocks we are currently scanning will not change out + * from under us. While a scan is active, this function controls how quickly + * transaction groups proceed, instead of the normal handling provided by + * txg_sync_thread(). + */ +void +dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx) +{ + int err = 0; + dsl_scan_t *scn = dp->dp_scan; + spa_t *spa = dp->dp_spa; + state_sync_type_t sync_type = SYNC_OPTIONAL; + + if (spa->spa_resilver_deferred && + !spa_feature_is_active(dp->dp_spa, SPA_FEATURE_RESILVER_DEFER)) + spa_feature_incr(spa, SPA_FEATURE_RESILVER_DEFER, tx); + + /* + * Check for scn_restart_txg before checking spa_load_state, so + * that we can restart an old-style scan while the pool is being + * imported (see dsl_scan_init). We also restart scans if there + * is a deferred resilver and the user has manually disabled + * deferred resilvers via the tunable. + */ + if (dsl_scan_restarting(scn, tx) || + (spa->spa_resilver_deferred && zfs_resilver_disable_defer)) { + pool_scan_func_t func = POOL_SCAN_SCRUB; + dsl_scan_done(scn, B_FALSE, tx); + if (vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL)) + func = POOL_SCAN_RESILVER; + zfs_dbgmsg("restarting scan func=%u txg=%llu", + func, (longlong_t)tx->tx_txg); + dsl_scan_setup_sync(&func, tx); + } + + /* + * Only process scans in sync pass 1. + */ + if (spa_sync_pass(spa) > 1) + return; + + /* + * If the spa is shutting down, then stop scanning. This will + * ensure that the scan does not dirty any new data during the + * shutdown phase. + */ + if (spa_shutting_down(spa)) + return; + + /* + * If the scan is inactive due to a stalled async destroy, try again. + */ + if (!scn->scn_async_stalled && !dsl_scan_active(scn)) + return; + + /* reset scan statistics */ + scn->scn_visited_this_txg = 0; + scn->scn_dedup_frees_this_txg = 0; + scn->scn_holes_this_txg = 0; + scn->scn_lt_min_this_txg = 0; + scn->scn_gt_max_this_txg = 0; + scn->scn_ddt_contained_this_txg = 0; + scn->scn_objsets_visited_this_txg = 0; + scn->scn_avg_seg_size_this_txg = 0; + scn->scn_segs_this_txg = 0; + scn->scn_avg_zio_size_this_txg = 0; + scn->scn_zios_this_txg = 0; + scn->scn_suspending = B_FALSE; + scn->scn_sync_start_time = gethrtime(); + spa->spa_scrub_active = B_TRUE; + + /* + * First process the async destroys. If we suspend, don't do + * any scrubbing or resilvering. This ensures that there are no + * async destroys while we are scanning, so the scan code doesn't + * have to worry about traversing it. It is also faster to free the + * blocks than to scrub them. + */ + err = dsl_process_async_destroys(dp, tx); + if (err != 0) + return; + + if (!dsl_scan_is_running(scn) || dsl_scan_is_paused_scrub(scn)) + return; + + /* + * Wait a few txgs after importing to begin scanning so that + * we can get the pool imported quickly. + */ + if (spa->spa_syncing_txg < spa->spa_first_txg + SCAN_IMPORT_WAIT_TXGS) + return; + + /* + * zfs_scan_suspend_progress can be set to disable scan progress. + * We don't want to spin the txg_sync thread, so we add a delay + * here to simulate the time spent doing a scan. This is mostly + * useful for testing and debugging. + */ + if (zfs_scan_suspend_progress) { + uint64_t scan_time_ns = gethrtime() - scn->scn_sync_start_time; + int mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ? + zfs_resilver_min_time_ms : zfs_scrub_min_time_ms; + + while (zfs_scan_suspend_progress && + !txg_sync_waiting(scn->scn_dp) && + !spa_shutting_down(scn->scn_dp->dp_spa) && + NSEC2MSEC(scan_time_ns) < mintime) { + delay(hz); + scan_time_ns = gethrtime() - scn->scn_sync_start_time; + } + return; + } + + /* + * It is possible to switch from unsorted to sorted at any time, + * but afterwards the scan will remain sorted unless reloaded from + * a checkpoint after a reboot. + */ + if (!zfs_scan_legacy) { + scn->scn_is_sorted = B_TRUE; + if (scn->scn_last_checkpoint == 0) + scn->scn_last_checkpoint = ddi_get_lbolt(); + } + + /* + * For sorted scans, determine what kind of work we will be doing + * this txg based on our memory limitations and whether or not we + * need to perform a checkpoint. + */ + if (scn->scn_is_sorted) { + /* + * If we are over our checkpoint interval, set scn_clearing + * so that we can begin checkpointing immediately. The + * checkpoint allows us to save a consistent bookmark + * representing how much data we have scrubbed so far. + * Otherwise, use the memory limit to determine if we should + * scan for metadata or start issue scrub IOs. We accumulate + * metadata until we hit our hard memory limit at which point + * we issue scrub IOs until we are at our soft memory limit. + */ + if (scn->scn_checkpointing || + ddi_get_lbolt() - scn->scn_last_checkpoint > + SEC_TO_TICK(zfs_scan_checkpoint_intval)) { + if (!scn->scn_checkpointing) + zfs_dbgmsg("begin scan checkpoint"); + + scn->scn_checkpointing = B_TRUE; + scn->scn_clearing = B_TRUE; + } else { + boolean_t should_clear = dsl_scan_should_clear(scn); + if (should_clear && !scn->scn_clearing) { + zfs_dbgmsg("begin scan clearing"); + scn->scn_clearing = B_TRUE; + } else if (!should_clear && scn->scn_clearing) { + zfs_dbgmsg("finish scan clearing"); + scn->scn_clearing = B_FALSE; + } + } + } else { + ASSERT0(scn->scn_checkpointing); + ASSERT0(scn->scn_clearing); + } + + if (!scn->scn_clearing && scn->scn_done_txg == 0) { + /* Need to scan metadata for more blocks to scrub */ + dsl_scan_phys_t *scnp = &scn->scn_phys; + taskqid_t prefetch_tqid; + uint64_t bytes_per_leaf = zfs_scan_vdev_limit; + uint64_t nr_leaves = dsl_scan_count_leaves(spa->spa_root_vdev); + + /* + * Recalculate the max number of in-flight bytes for pool-wide + * scanning operations (minimum 1MB). Limits for the issuing + * phase are done per top-level vdev and are handled separately. + */ + scn->scn_maxinflight_bytes = + MAX(nr_leaves * bytes_per_leaf, 1ULL << 20); + + if (scnp->scn_ddt_bookmark.ddb_class <= + scnp->scn_ddt_class_max) { + ASSERT(ZB_IS_ZERO(&scnp->scn_bookmark)); + zfs_dbgmsg("doing scan sync txg %llu; " + "ddt bm=%llu/%llu/%llu/%llx", + (longlong_t)tx->tx_txg, + (longlong_t)scnp->scn_ddt_bookmark.ddb_class, + (longlong_t)scnp->scn_ddt_bookmark.ddb_type, + (longlong_t)scnp->scn_ddt_bookmark.ddb_checksum, + (longlong_t)scnp->scn_ddt_bookmark.ddb_cursor); + } else { + zfs_dbgmsg("doing scan sync txg %llu; " + "bm=%llu/%llu/%llu/%llu", + (longlong_t)tx->tx_txg, + (longlong_t)scnp->scn_bookmark.zb_objset, + (longlong_t)scnp->scn_bookmark.zb_object, + (longlong_t)scnp->scn_bookmark.zb_level, + (longlong_t)scnp->scn_bookmark.zb_blkid); + } + + scn->scn_zio_root = zio_root(dp->dp_spa, NULL, + NULL, ZIO_FLAG_CANFAIL); + + scn->scn_prefetch_stop = B_FALSE; + prefetch_tqid = taskq_dispatch(dp->dp_sync_taskq, + dsl_scan_prefetch_thread, scn, TQ_SLEEP); + ASSERT(prefetch_tqid != TASKQID_INVALID); + + dsl_pool_config_enter(dp, FTAG); + dsl_scan_visit(scn, tx); + dsl_pool_config_exit(dp, FTAG); + + mutex_enter(&dp->dp_spa->spa_scrub_lock); + scn->scn_prefetch_stop = B_TRUE; + cv_broadcast(&spa->spa_scrub_io_cv); + mutex_exit(&dp->dp_spa->spa_scrub_lock); + + taskq_wait_id(dp->dp_sync_taskq, prefetch_tqid); + (void) zio_wait(scn->scn_zio_root); + scn->scn_zio_root = NULL; + + zfs_dbgmsg("scan visited %llu blocks in %llums " + "(%llu os's, %llu holes, %llu < mintxg, " + "%llu in ddt, %llu > maxtxg)", + (longlong_t)scn->scn_visited_this_txg, + (longlong_t)NSEC2MSEC(gethrtime() - + scn->scn_sync_start_time), + (longlong_t)scn->scn_objsets_visited_this_txg, + (longlong_t)scn->scn_holes_this_txg, + (longlong_t)scn->scn_lt_min_this_txg, + (longlong_t)scn->scn_ddt_contained_this_txg, + (longlong_t)scn->scn_gt_max_this_txg); + + if (!scn->scn_suspending) { + ASSERT0(avl_numnodes(&scn->scn_queue)); + scn->scn_done_txg = tx->tx_txg + 1; + if (scn->scn_is_sorted) { + scn->scn_checkpointing = B_TRUE; + scn->scn_clearing = B_TRUE; + } + zfs_dbgmsg("scan complete txg %llu", + (longlong_t)tx->tx_txg); + } + } else if (scn->scn_is_sorted && scn->scn_bytes_pending != 0) { + ASSERT(scn->scn_clearing); + + /* need to issue scrubbing IOs from per-vdev queues */ + scn->scn_zio_root = zio_root(dp->dp_spa, NULL, + NULL, ZIO_FLAG_CANFAIL); + scan_io_queues_run(scn); + (void) zio_wait(scn->scn_zio_root); + scn->scn_zio_root = NULL; + + /* calculate and dprintf the current memory usage */ + (void) dsl_scan_should_clear(scn); + dsl_scan_update_stats(scn); + + zfs_dbgmsg("scan issued %llu blocks (%llu segs) in %llums " + "(avg_block_size = %llu, avg_seg_size = %llu)", + (longlong_t)scn->scn_zios_this_txg, + (longlong_t)scn->scn_segs_this_txg, + (longlong_t)NSEC2MSEC(gethrtime() - + scn->scn_sync_start_time), + (longlong_t)scn->scn_avg_zio_size_this_txg, + (longlong_t)scn->scn_avg_seg_size_this_txg); + } else if (scn->scn_done_txg != 0 && scn->scn_done_txg <= tx->tx_txg) { + /* Finished with everything. Mark the scrub as complete */ + zfs_dbgmsg("scan issuing complete txg %llu", + (longlong_t)tx->tx_txg); + ASSERT3U(scn->scn_done_txg, !=, 0); + ASSERT0(spa->spa_scrub_inflight); + ASSERT0(scn->scn_bytes_pending); + dsl_scan_done(scn, B_TRUE, tx); + sync_type = SYNC_MANDATORY; + } + + dsl_scan_sync_state(scn, tx, sync_type); +} + +static void +count_block(dsl_scan_t *scn, zfs_all_blkstats_t *zab, const blkptr_t *bp) +{ + int i; + + /* + * Don't count embedded bp's, since we already did the work of + * scanning these when we scanned the containing block. + */ + if (BP_IS_EMBEDDED(bp)) + return; + + /* + * Update the spa's stats on how many bytes we have issued. + * Sequential scrubs create a zio for each DVA of the bp. Each + * of these will include all DVAs for repair purposes, but the + * zio code will only try the first one unless there is an issue. + * Therefore, we should only count the first DVA for these IOs. + */ + if (scn->scn_is_sorted) { + atomic_add_64(&scn->scn_dp->dp_spa->spa_scan_pass_issued, + DVA_GET_ASIZE(&bp->blk_dva[0])); + } else { + spa_t *spa = scn->scn_dp->dp_spa; + + for (i = 0; i < BP_GET_NDVAS(bp); i++) { + atomic_add_64(&spa->spa_scan_pass_issued, + DVA_GET_ASIZE(&bp->blk_dva[i])); + } + } + + /* + * If we resume after a reboot, zab will be NULL; don't record + * incomplete stats in that case. + */ + if (zab == NULL) + return; + + mutex_enter(&zab->zab_lock); + + for (i = 0; i < 4; i++) { + int l = (i < 2) ? BP_GET_LEVEL(bp) : DN_MAX_LEVELS; + int t = (i & 1) ? BP_GET_TYPE(bp) : DMU_OT_TOTAL; + + if (t & DMU_OT_NEWTYPE) + t = DMU_OT_OTHER; + zfs_blkstat_t *zb = &zab->zab_type[l][t]; + int equal; + + zb->zb_count++; + zb->zb_asize += BP_GET_ASIZE(bp); + zb->zb_lsize += BP_GET_LSIZE(bp); + zb->zb_psize += BP_GET_PSIZE(bp); + zb->zb_gangs += BP_COUNT_GANG(bp); + + switch (BP_GET_NDVAS(bp)) { + case 2: + if (DVA_GET_VDEV(&bp->blk_dva[0]) == + DVA_GET_VDEV(&bp->blk_dva[1])) + zb->zb_ditto_2_of_2_samevdev++; + break; + case 3: + equal = (DVA_GET_VDEV(&bp->blk_dva[0]) == + DVA_GET_VDEV(&bp->blk_dva[1])) + + (DVA_GET_VDEV(&bp->blk_dva[0]) == + DVA_GET_VDEV(&bp->blk_dva[2])) + + (DVA_GET_VDEV(&bp->blk_dva[1]) == + DVA_GET_VDEV(&bp->blk_dva[2])); + if (equal == 1) + zb->zb_ditto_2_of_3_samevdev++; + else if (equal == 3) + zb->zb_ditto_3_of_3_samevdev++; + break; + } + } + + mutex_exit(&zab->zab_lock); +} + +static void +scan_io_queue_insert_impl(dsl_scan_io_queue_t *queue, scan_io_t *sio) +{ + avl_index_t idx; + int64_t asize = SIO_GET_ASIZE(sio); + dsl_scan_t *scn = queue->q_scn; + + ASSERT(MUTEX_HELD(&queue->q_vd->vdev_scan_io_queue_lock)); + + if (avl_find(&queue->q_sios_by_addr, sio, &idx) != NULL) { + /* block is already scheduled for reading */ + atomic_add_64(&scn->scn_bytes_pending, -asize); + sio_free(sio); + return; + } + avl_insert(&queue->q_sios_by_addr, sio, idx); + queue->q_sio_memused += SIO_GET_MUSED(sio); + range_tree_add(queue->q_exts_by_addr, SIO_GET_OFFSET(sio), asize); +} + +/* + * Given all the info we got from our metadata scanning process, we + * construct a scan_io_t and insert it into the scan sorting queue. The + * I/O must already be suitable for us to process. This is controlled + * by dsl_scan_enqueue(). + */ +static void +scan_io_queue_insert(dsl_scan_io_queue_t *queue, const blkptr_t *bp, int dva_i, + int zio_flags, const zbookmark_phys_t *zb) +{ + dsl_scan_t *scn = queue->q_scn; + scan_io_t *sio = sio_alloc(BP_GET_NDVAS(bp)); + + ASSERT0(BP_IS_GANG(bp)); + ASSERT(MUTEX_HELD(&queue->q_vd->vdev_scan_io_queue_lock)); + + bp2sio(bp, sio, dva_i); + sio->sio_flags = zio_flags; + sio->sio_zb = *zb; + + /* + * Increment the bytes pending counter now so that we can't + * get an integer underflow in case the worker processes the + * zio before we get to incrementing this counter. + */ + atomic_add_64(&scn->scn_bytes_pending, SIO_GET_ASIZE(sio)); + + scan_io_queue_insert_impl(queue, sio); +} + +/* + * Given a set of I/O parameters as discovered by the metadata traversal + * process, attempts to place the I/O into the sorted queues (if allowed), + * or immediately executes the I/O. + */ +static void +dsl_scan_enqueue(dsl_pool_t *dp, const blkptr_t *bp, int zio_flags, + const zbookmark_phys_t *zb) +{ + spa_t *spa = dp->dp_spa; + + ASSERT(!BP_IS_EMBEDDED(bp)); + + /* + * Gang blocks are hard to issue sequentially, so we just issue them + * here immediately instead of queuing them. + */ + if (!dp->dp_scan->scn_is_sorted || BP_IS_GANG(bp)) { + scan_exec_io(dp, bp, zio_flags, zb, NULL); + return; + } + + for (int i = 0; i < BP_GET_NDVAS(bp); i++) { + dva_t dva; + vdev_t *vdev; + + dva = bp->blk_dva[i]; + vdev = vdev_lookup_top(spa, DVA_GET_VDEV(&dva)); + ASSERT(vdev != NULL); + + mutex_enter(&vdev->vdev_scan_io_queue_lock); + if (vdev->vdev_scan_io_queue == NULL) + vdev->vdev_scan_io_queue = scan_io_queue_create(vdev); + ASSERT(dp->dp_scan != NULL); + scan_io_queue_insert(vdev->vdev_scan_io_queue, bp, + i, zio_flags, zb); + mutex_exit(&vdev->vdev_scan_io_queue_lock); + } +} + +static int +dsl_scan_scrub_cb(dsl_pool_t *dp, + const blkptr_t *bp, const zbookmark_phys_t *zb) +{ + dsl_scan_t *scn = dp->dp_scan; + spa_t *spa = dp->dp_spa; + uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp); + size_t psize = BP_GET_PSIZE(bp); + boolean_t needs_io = B_FALSE; + int zio_flags = ZIO_FLAG_SCAN_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL; + + + if (phys_birth <= scn->scn_phys.scn_min_txg || + phys_birth >= scn->scn_phys.scn_max_txg) { + count_block(scn, dp->dp_blkstats, bp); + return (0); + } + + /* Embedded BP's have phys_birth==0, so we reject them above. */ + ASSERT(!BP_IS_EMBEDDED(bp)); + + ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn)); + if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) { + zio_flags |= ZIO_FLAG_SCRUB; + needs_io = B_TRUE; + } else { + ASSERT3U(scn->scn_phys.scn_func, ==, POOL_SCAN_RESILVER); + zio_flags |= ZIO_FLAG_RESILVER; + needs_io = B_FALSE; + } + + /* If it's an intent log block, failure is expected. */ + if (zb->zb_level == ZB_ZIL_LEVEL) + zio_flags |= ZIO_FLAG_SPECULATIVE; + + for (int d = 0; d < BP_GET_NDVAS(bp); d++) { + const dva_t *dva = &bp->blk_dva[d]; + + /* + * Keep track of how much data we've examined so that + * zpool(1M) status can make useful progress reports. + */ + scn->scn_phys.scn_examined += DVA_GET_ASIZE(dva); + spa->spa_scan_pass_exam += DVA_GET_ASIZE(dva); + + /* if it's a resilver, this may not be in the target range */ + if (!needs_io) + needs_io = dsl_scan_need_resilver(spa, dva, psize, + phys_birth); + } + + if (needs_io && !zfs_no_scrub_io) { + dsl_scan_enqueue(dp, bp, zio_flags, zb); + } else { + count_block(scn, dp->dp_blkstats, bp); + } + + /* do not relocate this block */ + return (0); +} + +static void +dsl_scan_scrub_done(zio_t *zio) +{ + spa_t *spa = zio->io_spa; + blkptr_t *bp = zio->io_bp; + dsl_scan_io_queue_t *queue = zio->io_private; + + abd_free(zio->io_abd); + + if (queue == NULL) { + mutex_enter(&spa->spa_scrub_lock); + ASSERT3U(spa->spa_scrub_inflight, >=, BP_GET_PSIZE(bp)); + spa->spa_scrub_inflight -= BP_GET_PSIZE(bp); + cv_broadcast(&spa->spa_scrub_io_cv); + mutex_exit(&spa->spa_scrub_lock); + } else { + mutex_enter(&queue->q_vd->vdev_scan_io_queue_lock); + ASSERT3U(queue->q_inflight_bytes, >=, BP_GET_PSIZE(bp)); + queue->q_inflight_bytes -= BP_GET_PSIZE(bp); + cv_broadcast(&queue->q_zio_cv); + mutex_exit(&queue->q_vd->vdev_scan_io_queue_lock); + } + + if (zio->io_error && (zio->io_error != ECKSUM || + !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) { + atomic_inc_64(&spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors); + } +} + +/* + * Given a scanning zio's information, executes the zio. The zio need + * not necessarily be only sortable, this function simply executes the + * zio, no matter what it is. The optional queue argument allows the + * caller to specify that they want per top level vdev IO rate limiting + * instead of the legacy global limiting. + */ +static void +scan_exec_io(dsl_pool_t *dp, const blkptr_t *bp, int zio_flags, + const zbookmark_phys_t *zb, dsl_scan_io_queue_t *queue) +{ + spa_t *spa = dp->dp_spa; + dsl_scan_t *scn = dp->dp_scan; + size_t size = BP_GET_PSIZE(bp); + abd_t *data = abd_alloc_for_io(size, B_FALSE); + + ASSERT3U(scn->scn_maxinflight_bytes, >, 0); + + if (queue == NULL) { + mutex_enter(&spa->spa_scrub_lock); + while (spa->spa_scrub_inflight >= scn->scn_maxinflight_bytes) + cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock); + spa->spa_scrub_inflight += BP_GET_PSIZE(bp); + mutex_exit(&spa->spa_scrub_lock); + } else { + kmutex_t *q_lock = &queue->q_vd->vdev_scan_io_queue_lock; + + mutex_enter(q_lock); + while (queue->q_inflight_bytes >= queue->q_maxinflight_bytes) + cv_wait(&queue->q_zio_cv, q_lock); + queue->q_inflight_bytes += BP_GET_PSIZE(bp); + mutex_exit(q_lock); + } + + count_block(scn, dp->dp_blkstats, bp); + zio_nowait(zio_read(scn->scn_zio_root, spa, bp, data, size, + dsl_scan_scrub_done, queue, ZIO_PRIORITY_SCRUB, zio_flags, zb)); +} + +/* + * This is the primary extent sorting algorithm. We balance two parameters: + * 1) how many bytes of I/O are in an extent + * 2) how well the extent is filled with I/O (as a fraction of its total size) + * Since we allow extents to have gaps between their constituent I/Os, it's + * possible to have a fairly large extent that contains the same amount of + * I/O bytes than a much smaller extent, which just packs the I/O more tightly. + * The algorithm sorts based on a score calculated from the extent's size, + * the relative fill volume (in %) and a "fill weight" parameter that controls + * the split between whether we prefer larger extents or more well populated + * extents: + * + * SCORE = FILL_IN_BYTES + (FILL_IN_PERCENT * FILL_IN_BYTES * FILL_WEIGHT) + * + * Example: + * 1) assume extsz = 64 MiB + * 2) assume fill = 32 MiB (extent is half full) + * 3) assume fill_weight = 3 + * 4) SCORE = 32M + (((32M * 100) / 64M) * 3 * 32M) / 100 + * SCORE = 32M + (50 * 3 * 32M) / 100 + * SCORE = 32M + (4800M / 100) + * SCORE = 32M + 48M + * ^ ^ + * | +--- final total relative fill-based score + * +--------- final total fill-based score + * SCORE = 80M + * + * As can be seen, at fill_ratio=3, the algorithm is slightly biased towards + * extents that are more completely filled (in a 3:2 ratio) vs just larger. + * Note that as an optimization, we replace multiplication and division by + * 100 with bitshifting by 7 (which effectively multiplies and divides by 128). + */ +static int +ext_size_compare(const void *x, const void *y) +{ + const range_seg_gap_t *rsa = x, *rsb = y; + + uint64_t sa = rsa->rs_end - rsa->rs_start; + uint64_t sb = rsb->rs_end - rsb->rs_start; + uint64_t score_a, score_b; + + score_a = rsa->rs_fill + ((((rsa->rs_fill << 7) / sa) * + fill_weight * rsa->rs_fill) >> 7); + score_b = rsb->rs_fill + ((((rsb->rs_fill << 7) / sb) * + fill_weight * rsb->rs_fill) >> 7); + + if (score_a > score_b) + return (-1); + if (score_a == score_b) { + if (rsa->rs_start < rsb->rs_start) + return (-1); + if (rsa->rs_start == rsb->rs_start) + return (0); + return (1); + } + return (1); +} + +/* + * Comparator for the q_sios_by_addr tree. Sorting is simply performed + * based on LBA-order (from lowest to highest). + */ +static int +sio_addr_compare(const void *x, const void *y) +{ + const scan_io_t *a = x, *b = y; + + return (TREE_CMP(SIO_GET_OFFSET(a), SIO_GET_OFFSET(b))); +} + +/* IO queues are created on demand when they are needed. */ +static dsl_scan_io_queue_t * +scan_io_queue_create(vdev_t *vd) +{ + dsl_scan_t *scn = vd->vdev_spa->spa_dsl_pool->dp_scan; + dsl_scan_io_queue_t *q = kmem_zalloc(sizeof (*q), KM_SLEEP); + + q->q_scn = scn; + q->q_vd = vd; + q->q_sio_memused = 0; + cv_init(&q->q_zio_cv, NULL, CV_DEFAULT, NULL); + q->q_exts_by_addr = range_tree_create_impl(&rt_btree_ops, RANGE_SEG_GAP, + &q->q_exts_by_size, 0, 0, ext_size_compare, zfs_scan_max_ext_gap); + avl_create(&q->q_sios_by_addr, sio_addr_compare, + sizeof (scan_io_t), offsetof(scan_io_t, sio_nodes.sio_addr_node)); + + return (q); +} + +/* + * Destroys a scan queue and all segments and scan_io_t's contained in it. + * No further execution of I/O occurs, anything pending in the queue is + * simply freed without being executed. + */ +void +dsl_scan_io_queue_destroy(dsl_scan_io_queue_t *queue) +{ + dsl_scan_t *scn = queue->q_scn; + scan_io_t *sio; + void *cookie = NULL; + int64_t bytes_dequeued = 0; + + ASSERT(MUTEX_HELD(&queue->q_vd->vdev_scan_io_queue_lock)); + + while ((sio = avl_destroy_nodes(&queue->q_sios_by_addr, &cookie)) != + NULL) { + ASSERT(range_tree_contains(queue->q_exts_by_addr, + SIO_GET_OFFSET(sio), SIO_GET_ASIZE(sio))); + bytes_dequeued += SIO_GET_ASIZE(sio); + queue->q_sio_memused -= SIO_GET_MUSED(sio); + sio_free(sio); + } + + ASSERT0(queue->q_sio_memused); + atomic_add_64(&scn->scn_bytes_pending, -bytes_dequeued); + range_tree_vacate(queue->q_exts_by_addr, NULL, queue); + range_tree_destroy(queue->q_exts_by_addr); + avl_destroy(&queue->q_sios_by_addr); + cv_destroy(&queue->q_zio_cv); + + kmem_free(queue, sizeof (*queue)); +} + +/* + * Properly transfers a dsl_scan_queue_t from `svd' to `tvd'. This is + * called on behalf of vdev_top_transfer when creating or destroying + * a mirror vdev due to zpool attach/detach. + */ +void +dsl_scan_io_queue_vdev_xfer(vdev_t *svd, vdev_t *tvd) +{ + mutex_enter(&svd->vdev_scan_io_queue_lock); + mutex_enter(&tvd->vdev_scan_io_queue_lock); + + VERIFY3P(tvd->vdev_scan_io_queue, ==, NULL); + tvd->vdev_scan_io_queue = svd->vdev_scan_io_queue; + svd->vdev_scan_io_queue = NULL; + if (tvd->vdev_scan_io_queue != NULL) + tvd->vdev_scan_io_queue->q_vd = tvd; + + mutex_exit(&tvd->vdev_scan_io_queue_lock); + mutex_exit(&svd->vdev_scan_io_queue_lock); +} + +static void +scan_io_queues_destroy(dsl_scan_t *scn) +{ + vdev_t *rvd = scn->scn_dp->dp_spa->spa_root_vdev; + + for (uint64_t i = 0; i < rvd->vdev_children; i++) { + vdev_t *tvd = rvd->vdev_child[i]; + + mutex_enter(&tvd->vdev_scan_io_queue_lock); + if (tvd->vdev_scan_io_queue != NULL) + dsl_scan_io_queue_destroy(tvd->vdev_scan_io_queue); + tvd->vdev_scan_io_queue = NULL; + mutex_exit(&tvd->vdev_scan_io_queue_lock); + } +} + +static void +dsl_scan_freed_dva(spa_t *spa, const blkptr_t *bp, int dva_i) +{ + dsl_pool_t *dp = spa->spa_dsl_pool; + dsl_scan_t *scn = dp->dp_scan; + vdev_t *vdev; + kmutex_t *q_lock; + dsl_scan_io_queue_t *queue; + scan_io_t *srch_sio, *sio; + avl_index_t idx; + uint64_t start, size; + + vdev = vdev_lookup_top(spa, DVA_GET_VDEV(&bp->blk_dva[dva_i])); + ASSERT(vdev != NULL); + q_lock = &vdev->vdev_scan_io_queue_lock; + queue = vdev->vdev_scan_io_queue; + + mutex_enter(q_lock); + if (queue == NULL) { + mutex_exit(q_lock); + return; + } + + srch_sio = sio_alloc(BP_GET_NDVAS(bp)); + bp2sio(bp, srch_sio, dva_i); + start = SIO_GET_OFFSET(srch_sio); + size = SIO_GET_ASIZE(srch_sio); + + /* + * We can find the zio in two states: + * 1) Cold, just sitting in the queue of zio's to be issued at + * some point in the future. In this case, all we do is + * remove the zio from the q_sios_by_addr tree, decrement + * its data volume from the containing range_seg_t and + * resort the q_exts_by_size tree to reflect that the + * range_seg_t has lost some of its 'fill'. We don't shorten + * the range_seg_t - this is usually rare enough not to be + * worth the extra hassle of trying keep track of precise + * extent boundaries. + * 2) Hot, where the zio is currently in-flight in + * dsl_scan_issue_ios. In this case, we can't simply + * reach in and stop the in-flight zio's, so we instead + * block the caller. Eventually, dsl_scan_issue_ios will + * be done with issuing the zio's it gathered and will + * signal us. + */ + sio = avl_find(&queue->q_sios_by_addr, srch_sio, &idx); + sio_free(srch_sio); + + if (sio != NULL) { + int64_t asize = SIO_GET_ASIZE(sio); + blkptr_t tmpbp; + + /* Got it while it was cold in the queue */ + ASSERT3U(start, ==, SIO_GET_OFFSET(sio)); + ASSERT3U(size, ==, asize); + avl_remove(&queue->q_sios_by_addr, sio); + queue->q_sio_memused -= SIO_GET_MUSED(sio); + + ASSERT(range_tree_contains(queue->q_exts_by_addr, start, size)); + range_tree_remove_fill(queue->q_exts_by_addr, start, size); + + /* + * We only update scn_bytes_pending in the cold path, + * otherwise it will already have been accounted for as + * part of the zio's execution. + */ + atomic_add_64(&scn->scn_bytes_pending, -asize); + + /* count the block as though we issued it */ + sio2bp(sio, &tmpbp); + count_block(scn, dp->dp_blkstats, &tmpbp); + + sio_free(sio); + } + mutex_exit(q_lock); +} + +/* + * Callback invoked when a zio_free() zio is executing. This needs to be + * intercepted to prevent the zio from deallocating a particular portion + * of disk space and it then getting reallocated and written to, while we + * still have it queued up for processing. + */ +void +dsl_scan_freed(spa_t *spa, const blkptr_t *bp) +{ + dsl_pool_t *dp = spa->spa_dsl_pool; + dsl_scan_t *scn = dp->dp_scan; + + ASSERT(!BP_IS_EMBEDDED(bp)); + ASSERT(scn != NULL); + if (!dsl_scan_is_running(scn)) + return; + + for (int i = 0; i < BP_GET_NDVAS(bp); i++) + dsl_scan_freed_dva(spa, bp, i); +} + +/* + * Check if a vdev needs resilvering (non-empty DTL), if so, and resilver has + * not started, start it. Otherwise, only restart if max txg in DTL range is + * greater than the max txg in the current scan. If the DTL max is less than + * the scan max, then the vdev has not missed any new data since the resilver + * started, so a restart is not needed. + */ +void +dsl_scan_assess_vdev(dsl_pool_t *dp, vdev_t *vd) +{ + uint64_t min, max; + + if (!vdev_resilver_needed(vd, &min, &max)) + return; + + if (!dsl_scan_resilvering(dp)) { + spa_async_request(dp->dp_spa, SPA_ASYNC_RESILVER); + return; + } + + if (max <= dp->dp_scan->scn_phys.scn_max_txg) + return; + + /* restart is needed, check if it can be deferred */ + if (spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_RESILVER_DEFER)) + vdev_defer_resilver(vd); + else + spa_async_request(dp->dp_spa, SPA_ASYNC_RESILVER); +} + +/* BEGIN CSTYLED */ +ZFS_MODULE_PARAM(zfs, zfs_, scan_vdev_limit, ULONG, ZMOD_RW, + "Max bytes in flight per leaf vdev for scrubs and resilvers"); + +ZFS_MODULE_PARAM(zfs, zfs_, scrub_min_time_ms, INT, ZMOD_RW, + "Min millisecs to scrub per txg"); + +ZFS_MODULE_PARAM(zfs, zfs_, obsolete_min_time_ms, INT, ZMOD_RW, + "Min millisecs to obsolete per txg"); + +ZFS_MODULE_PARAM(zfs, zfs_, free_min_time_ms, INT, ZMOD_RW, + "Min millisecs to free per txg"); + +ZFS_MODULE_PARAM(zfs, zfs_, resilver_min_time_ms, INT, ZMOD_RW, + "Min millisecs to resilver per txg"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_suspend_progress, INT, ZMOD_RW, + "Set to prevent scans from progressing"); + +ZFS_MODULE_PARAM(zfs, zfs_, no_scrub_io, INT, ZMOD_RW, + "Set to disable scrub I/O"); + +ZFS_MODULE_PARAM(zfs, zfs_, no_scrub_prefetch, INT, ZMOD_RW, + "Set to disable scrub prefetching"); + +ZFS_MODULE_PARAM(zfs, zfs_, async_block_max_blocks, ULONG, ZMOD_RW, + "Max number of blocks freed in one txg"); + +ZFS_MODULE_PARAM(zfs, zfs_, max_async_dedup_frees, ULONG, ZMOD_RW, + "Max number of dedup blocks freed in one txg"); + +ZFS_MODULE_PARAM(zfs, zfs_, free_bpobj_enabled, INT, ZMOD_RW, + "Enable processing of the free_bpobj"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_mem_lim_fact, INT, ZMOD_RW, + "Fraction of RAM for scan hard limit"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_issue_strategy, INT, ZMOD_RW, + "IO issuing strategy during scrubbing. " + "0 = default, 1 = LBA, 2 = size"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_legacy, INT, ZMOD_RW, + "Scrub using legacy non-sequential method"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_checkpoint_intval, INT, ZMOD_RW, + "Scan progress on-disk checkpointing interval"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_max_ext_gap, ULONG, ZMOD_RW, + "Max gap in bytes between sequential scrub / resilver I/Os"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_mem_lim_soft_fact, INT, ZMOD_RW, + "Fraction of hard limit used as soft limit"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_strict_mem_lim, INT, ZMOD_RW, + "Tunable to attempt to reduce lock contention"); + +ZFS_MODULE_PARAM(zfs, zfs_, scan_fill_weight, INT, ZMOD_RW, + "Tunable to adjust bias towards more filled segments during scans"); + +ZFS_MODULE_PARAM(zfs, zfs_, resilver_disable_defer, INT, ZMOD_RW, + "Process all resilvers immediately"); +/* END CSTYLED */ |