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/*
* 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, 2017 by Delphix. All rights reserved.
* Copyright 2016 Gary Mills
* Copyright (c) 2017 Datto Inc.
* Copyright 2017 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 = 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_offset;
uint64_t sio_blk_prop;
uint64_t sio_phys_birth;
uint64_t sio_birth;
zio_cksum_t sio_cksum;
uint32_t sio_asize;
/* fields from zio_t */
int sio_flags;
zbookmark_phys_t sio_zb;
/* members for queue sorting */
union {
avl_node_t sio_addr_node; /* link into issueing queue */
list_node_t sio_list_node; /* link for issuing to disk */
} sio_nodes;
} scan_io_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;
avl_tree_t q_exts_by_size;
avl_tree_t q_sios_by_addr;
/* 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;
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;
sio_cache = kmem_cache_create("sio_cache",
sizeof (scan_io_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
}
void
scan_fini(void)
{
kmem_cache_destroy(sio_cache);
}
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, uint64_t vdev_id)
{
bzero(bp, sizeof (*bp));
DVA_SET_ASIZE(&bp->blk_dva[0], sio->sio_asize);
DVA_SET_VDEV(&bp->blk_dva[0], vdev_id);
DVA_SET_OFFSET(&bp->blk_dva[0], sio->sio_offset);
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;
}
static inline void
bp2sio(const blkptr_t *bp, scan_io_t *sio, int dva_i)
{
/* we discard the vdev id, since we can deduce it from the queue */
sio->sio_offset = DVA_GET_OFFSET(&bp->blk_dva[dva_i]);
sio->sio_asize = DVA_GET_ASIZE(&bp->blk_dva[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;
}
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);
}
}
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_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(avl_first(&q->q_exts_by_size), ==, 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;
if (dsl_scan_is_running(scn))
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)) {
spa_event_notify(spa, NULL, NULL,
ESC_ZFS_RESILVER_START);
} 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;
}
/* 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, scn->scn_phys.scn_min_txg, 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_resilver_restart(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 (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));
}
/*
* Sets the resilver defer flag to B_FALSE on all leaf devs under vd. Returns
* B_TRUE if we have devices that need to be resilvered and are available to
* accept resilver I/Os.
*/
static boolean_t
dsl_scan_clear_deferred(vdev_t *vd, dmu_tx_t *tx)
{
boolean_t resilver_needed = B_FALSE;
spa_t *spa = vd->vdev_spa;
for (int c = 0; c < vd->vdev_children; c++) {
resilver_needed |=
dsl_scan_clear_deferred(vd->vdev_child[c], tx);
}
if (vd == spa->spa_root_vdev &&
spa_feature_is_active(spa, SPA_FEATURE_RESILVER_DEFER)) {
spa_feature_decr(spa, SPA_FEATURE_RESILVER_DEFER, tx);
vdev_config_dirty(vd);
spa->spa_resilver_deferred = B_FALSE;
return (resilver_needed);
}
if (!vdev_is_concrete(vd) || vd->vdev_aux ||
!vd->vdev_ops->vdev_op_leaf)
return (resilver_needed);
if (vd->vdev_resilver_deferred)
vd->vdev_resilver_deferred = B_FALSE;
return (!vdev_is_dead(vd) && !vd->vdev_offline &&
vdev_resilver_needed(vd, NULL, NULL));
}
/* 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;
if (dsl_scan_restarting(scn, tx))
spa_history_log_internal(spa, "scan aborted, restarting", tx,
"errors=%llu", spa_get_errlog_size(spa));
else if (!complete)
spa_history_log_internal(spa, "scan cancelled", tx,
"errors=%llu", spa_get_errlog_size(spa));
else
spa_history_log_internal(spa, "scan done", tx,
"errors=%llu", spa_get_errlog_size(spa));
if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
spa->spa_scrub_started = B_FALSE;
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);
spa_event_notify(spa, NULL, NULL,
scn->scn_phys.scn_min_txg ?
ESC_ZFS_RESILVER_FINISH : ESC_ZFS_SCRUB_FINISH);
} else {
vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
0, B_TRUE);
}
spa_errlog_rotate(spa);
/*
* 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 deferred_resilver flags in the config.
* If there are drives that need resilvering, kick
* off an asynchronous request to start resilver.
* dsl_scan_clear_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
* when the machine reboots and start the resilver then.
*/
boolean_t resilver_needed =
dsl_scan_clear_deferred(spa->spa_root_vdev, tx);
if (resilver_needed) {
spa_history_log_internal(spa,
"starting deferred resilver", tx,
"errors=%llu", 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);
} 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_resilver_restart(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)
{
vdev_t *rvd = scn->scn_dp->dp_spa->spa_root_vdev;
uint64_t mlim_hard, mlim_soft, mused;
uint64_t alloc = metaslab_class_get_alloc(spa_normal_class(
scn->scn_dp->dp_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 += avl_numnodes(&queue->q_exts_by_size) *
sizeof (range_seg_t) +
avl_numnodes(&queue->q_sios_by_addr) *
sizeof (scan_io_t);
}
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 blocks. */
if (zb && zb->zb_level != 0)
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) {
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;
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;
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)
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);
}
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;
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 addes 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->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 a parent dataset and its clone are swapped. If we were
* currently traversing the dataset, we need to switch to traversing the
* newly promoted parent.
*/
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 mintxg;
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);
if (scan_ds_queue_contains(scn, ds1->ds_object, &mintxg)) {
scan_ds_queue_remove(scn, ds1->ds_object);
scan_ds_queue_insert(scn, ds2->ds_object, mintxg);
}
if (scan_ds_queue_contains(scn, ds2->ds_object, &mintxg)) {
scan_ds_queue_remove(scn, ds2->ds_object);
scan_ds_queue_insert(scn, ds1->ds_object, mintxg);
}
if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
ds1->ds_object, &mintxg) == 0) {
int err;
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
err = zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
VERIFY(err == 0 || err == EEXIST);
if (err == EEXIST) {
/* Both were there to begin with */
VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj,
ds1->ds_object, mintxg, tx));
}
zfs_dbgmsg("clone_swap ds %llu; in queue; "
"replacing with %llu",
(u_longlong_t)ds1->ds_object,
(u_longlong_t)ds2->ds_object);
}
if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
ds2->ds_object, &mintxg) == 0) {
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, 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, queue->q_vd->vdev_id);
bytes_issued += sio->sio_asize;
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);
kmem_cache_free(sio_cache, 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_offset = rs->rs_start;
/*
* 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);
if (sio == NULL)
sio = avl_nearest(&queue->q_sios_by_addr, idx, AVL_AFTER);
while (sio != NULL && sio->sio_offset < rs->rs_end && num_sios <= 32) {
ASSERT3U(sio->sio_offset, >=, rs->rs_start);
ASSERT3U(sio->sio_offset + sio->sio_asize, <=, rs->rs_end);
next_sio = AVL_NEXT(&queue->q_sios_by_addr, sio);
avl_remove(&queue->q_sios_by_addr, sio);
bytes_issued += sio->sio_asize;
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->sio_offset < rs->rs_end) {
range_tree_adjust_fill(queue->q_exts_by_addr, rs,
-bytes_issued);
range_tree_resize_segment(queue->q_exts_by_addr, rs,
sio->sio_offset, rs->rs_end - sio->sio_offset);
return (B_TRUE);
} else {
range_tree_remove(queue->q_exts_by_addr, rs->rs_start,
rs->rs_end - rs->rs_start);
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;
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(queue->q_exts_by_addr));
} else if (zfs_scan_issue_strategy == 2) {
return (avl_first(&queue->q_exts_by_size));
}
}
/*
* 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(queue->q_exts_by_addr));
} else if (scn->scn_clearing) {
return (avl_first(&queue->q_exts_by_size));
} 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 = last_sio->sio_offset + last_sio->sio_asize;
if (seg_start == 0)
seg_start = first_sio->sio_offset;
/*
* 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 (scn->scn_visited_this_txg >= zfs_async_block_max_blocks)
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++;
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
dsl_scan_obsolete_block_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
{
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;
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);
}
return (used != 0);
}
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,
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;
/*
* 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) {
/* 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);
}
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
* cna 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_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;
/* update the spa's stats on how many bytes we have issued */
for (i = 0; i < BP_GET_NDVAS(bp); i++) {
atomic_add_64(&scn->scn_dp->dp_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->sio_asize;
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);
kmem_cache_free(sio_cache, sio);
return;
}
avl_insert(&queue->q_sios_by_addr, sio, idx);
range_tree_add(queue->q_exts_by_addr, sio->sio_offset, 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 = kmem_cache_alloc(sio_cache, KM_SLEEP);
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->sio_asize);
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 effecitvely multiplies and divides by 128).
*/
static int
ext_size_compare(const void *x, const void *y)
{
const range_seg_t *rsa = x, *rsb = y;
uint64_t sa = rsa->rs_end - rsa->rs_start,
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