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-rw-r--r--uts/common/fs/zfs/dsl_scan.c1766
1 files changed, 1766 insertions, 0 deletions
diff --git a/uts/common/fs/zfs/dsl_scan.c b/uts/common/fs/zfs/dsl_scan.c
new file mode 100644
index 000000000000..56d41083673e
--- /dev/null
+++ b/uts/common/fs/zfs/dsl_scan.c
@@ -0,0 +1,1766 @@
+/*
+ * 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.
+ */
+
+#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>
+#ifdef _KERNEL
+#include <sys/zfs_vfsops.h>
+#endif
+
+typedef int (scan_cb_t)(dsl_pool_t *, const blkptr_t *, const zbookmark_t *);
+
+static scan_cb_t dsl_scan_defrag_cb;
+static scan_cb_t dsl_scan_scrub_cb;
+static scan_cb_t dsl_scan_remove_cb;
+static dsl_syncfunc_t dsl_scan_cancel_sync;
+static void dsl_scan_sync_state(dsl_scan_t *, dmu_tx_t *tx);
+
+int zfs_top_maxinflight = 32; /* maximum I/Os per top-level */
+int zfs_resilver_delay = 2; /* number of ticks to delay resilver */
+int zfs_scrub_delay = 4; /* number of ticks to delay scrub */
+int zfs_scan_idle = 50; /* idle window in clock ticks */
+
+int zfs_scan_min_time_ms = 1000; /* min millisecs to scrub 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 */
+boolean_t zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */
+boolean_t zfs_no_scrub_prefetch = B_FALSE; /* set to disable srub prefetching */
+enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE;
+int dsl_scan_delay_completion = B_FALSE; /* set to delay scan completion */
+
+#define DSL_SCAN_IS_SCRUB_RESILVER(scn) \
+ ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
+ (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER)
+
+extern int zfs_txg_timeout;
+
+/* 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 */
+};
+
+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;
+
+ 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",
+ 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);
+ if (err == ENOENT)
+ return (0);
+ else if (err)
+ return (err);
+
+ if (scn->scn_phys.scn_state == DSS_SCANNING &&
+ 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",
+ scn->scn_restart_txg);
+ }
+ }
+
+ spa_scan_stat_init(spa);
+ return (0);
+}
+
+void
+dsl_scan_fini(dsl_pool_t *dp)
+{
+ if (dp->dp_scan) {
+ kmem_free(dp->dp_scan, sizeof (dsl_scan_t));
+ dp->dp_scan = NULL;
+ }
+}
+
+/* ARGSUSED */
+static int
+dsl_scan_setup_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+ dsl_scan_t *scn = arg1;
+
+ if (scn->scn_phys.scn_state == DSS_SCANNING)
+ return (EBUSY);
+
+ return (0);
+}
+
+/* ARGSUSED */
+static void
+dsl_scan_setup_sync(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+ dsl_scan_t *scn = arg1;
+ pool_scan_func_t *funcp = arg2;
+ dmu_object_type_t ot = 0;
+ dsl_pool_t *dp = scn->scn_dp;
+ spa_t *spa = dp->dp_spa;
+
+ ASSERT(scn->scn_phys.scn_state != DSS_SCANNING);
+ 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_restart_txg = 0;
+ 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, ESC_ZFS_RESILVER_START);
+ } else {
+ spa_event_notify(spa, 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 =
+ kmem_alloc(sizeof (zfs_all_blkstats_t), KM_SLEEP);
+ }
+ bzero(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
+
+ 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);
+
+ dsl_scan_sync_state(scn, tx);
+
+ spa_history_log_internal(LOG_POOL_SCAN, spa, tx,
+ "func=%u mintxg=%llu maxtxg=%llu",
+ *funcp, scn->scn_phys.scn_min_txg, scn->scn_phys.scn_max_txg);
+}
+
+/* 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) {
+ VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, tx));
+ scn->scn_phys.scn_queue_obj = 0;
+ }
+
+ /*
+ * If we were "restarted" from a stopped state, don't bother
+ * with anything else.
+ */
+ if (scn->scn_phys.scn_state != DSS_SCANNING)
+ return;
+
+ if (complete)
+ scn->scn_phys.scn_state = DSS_FINISHED;
+ else
+ scn->scn_phys.scn_state = DSS_CANCELED;
+
+ spa_history_log_internal(LOG_POOL_SCAN_DONE, spa, tx,
+ "complete=%u", complete);
+
+ if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
+ mutex_enter(&spa->spa_scrub_lock);
+ while (spa->spa_scrub_inflight > 0) {
+ cv_wait(&spa->spa_scrub_io_cv,
+ &spa->spa_scrub_lock);
+ }
+ mutex_exit(&spa->spa_scrub_lock);
+ 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.
+ */
+ vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
+ complete ? scn->scn_phys.scn_max_txg : 0, B_TRUE);
+ if (complete) {
+ spa_event_notify(spa, NULL, scn->scn_phys.scn_min_txg ?
+ ESC_ZFS_RESILVER_FINISH : ESC_ZFS_SCRUB_FINISH);
+ }
+ 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);
+ }
+
+ scn->scn_phys.scn_end_time = gethrestime_sec();
+}
+
+/* ARGSUSED */
+static int
+dsl_scan_cancel_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+ dsl_scan_t *scn = arg1;
+
+ if (scn->scn_phys.scn_state != DSS_SCANNING)
+ return (ENOENT);
+ return (0);
+}
+
+/* ARGSUSED */
+static void
+dsl_scan_cancel_sync(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+ dsl_scan_t *scn = arg1;
+
+ dsl_scan_done(scn, B_FALSE, tx);
+ dsl_scan_sync_state(scn, tx);
+}
+
+int
+dsl_scan_cancel(dsl_pool_t *dp)
+{
+ boolean_t complete = B_FALSE;
+ int err;
+
+ err = dsl_sync_task_do(dp, dsl_scan_cancel_check,
+ dsl_scan_cancel_sync, dp->dp_scan, &complete, 3);
+ return (err);
+}
+
+static void dsl_scan_visitbp(blkptr_t *bp,
+ const zbookmark_t *zb, dnode_phys_t *dnp, arc_buf_t *pbuf,
+ dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
+ dmu_tx_t *tx);
+static void dsl_scan_visitdnode(dsl_scan_t *, dsl_dataset_t *ds,
+ dmu_objset_type_t ostype,
+ dnode_phys_t *dnp, arc_buf_t *buf, uint64_t object, dmu_tx_t *tx);
+
+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));
+}
+
+int
+dsl_read(zio_t *pio, spa_t *spa, const blkptr_t *bpp, arc_buf_t *pbuf,
+ arc_done_func_t *done, void *private, int priority, int zio_flags,
+ uint32_t *arc_flags, const zbookmark_t *zb)
+{
+ return (arc_read(pio, spa, bpp, pbuf, done, private,
+ priority, zio_flags, arc_flags, zb));
+}
+
+int
+dsl_read_nolock(zio_t *pio, spa_t *spa, const blkptr_t *bpp,
+ arc_done_func_t *done, void *private, int priority, int zio_flags,
+ uint32_t *arc_flags, const zbookmark_t *zb)
+{
+ return (arc_read_nolock(pio, spa, bpp, done, private,
+ priority, zio_flags, arc_flags, zb));
+}
+
+static boolean_t
+bookmark_is_zero(const zbookmark_t *zb)
+{
+ return (zb->zb_objset == 0 && zb->zb_object == 0 &&
+ zb->zb_level == 0 && zb->zb_blkid == 0);
+}
+
+/* dnp is the dnode for zb1->zb_object */
+static boolean_t
+bookmark_is_before(const dnode_phys_t *dnp, const zbookmark_t *zb1,
+ const zbookmark_t *zb2)
+{
+ uint64_t zb1nextL0, zb2thisobj;
+
+ ASSERT(zb1->zb_objset == zb2->zb_objset);
+ ASSERT(zb2->zb_level == 0);
+
+ /*
+ * A bookmark in the deadlist is considered to be after
+ * everything else.
+ */
+ if (zb2->zb_object == DMU_DEADLIST_OBJECT)
+ return (B_TRUE);
+
+ /* The objset_phys_t isn't before anything. */
+ if (dnp == NULL)
+ return (B_FALSE);
+
+ zb1nextL0 = (zb1->zb_blkid + 1) <<
+ ((zb1->zb_level) * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT));
+
+ zb2thisobj = zb2->zb_object ? zb2->zb_object :
+ zb2->zb_blkid << (DNODE_BLOCK_SHIFT - DNODE_SHIFT);
+
+ if (zb1->zb_object == DMU_META_DNODE_OBJECT) {
+ uint64_t nextobj = zb1nextL0 *
+ (dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT) >> DNODE_SHIFT;
+ return (nextobj <= zb2thisobj);
+ }
+
+ if (zb1->zb_object < zb2thisobj)
+ return (B_TRUE);
+ if (zb1->zb_object > zb2thisobj)
+ return (B_FALSE);
+ if (zb2->zb_object == DMU_META_DNODE_OBJECT)
+ return (B_FALSE);
+ return (zb1nextL0 <= zb2->zb_blkid);
+}
+
+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 (dsl_dataset_is_snapshot(ds))
+ return (MIN(smt, ds->ds_phys->ds_creation_txg));
+ return (smt);
+}
+
+static void
+dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
+{
+ VERIFY(0 == 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));
+}
+
+static boolean_t
+dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_t *zb)
+{
+ uint64_t elapsed_nanosecs;
+ int mintime;
+
+ /* we never skip user/group accounting objects */
+ if (zb && (int64_t)zb->zb_object < 0)
+ return (B_FALSE);
+
+ if (scn->scn_pausing)
+ return (B_TRUE); /* we're already pausing */
+
+ if (!bookmark_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);
+
+ mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
+ zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
+ elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
+ if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
+ (elapsed_nanosecs / MICROSEC > mintime &&
+ txg_sync_waiting(scn->scn_dp)) ||
+ spa_shutting_down(scn->scn_dp->dp_spa)) {
+ if (zb) {
+ dprintf("pausing 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;
+ }
+ dprintf("pausing at DDT bookmark %llx/%llx/%llx/%llx\n",
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
+ scn->scn_pausing = 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_t zb;
+
+ if (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_first_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_t zb;
+
+ if (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;
+
+ /*
+ * 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 && spa_writeable(dp->dp_spa))
+ return;
+
+ zilog = zil_alloc(dp->dp_meta_objset, zh);
+
+ (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa,
+ claim_txg);
+
+ zil_free(zilog);
+}
+
+/* ARGSUSED */
+static void
+dsl_scan_prefetch(dsl_scan_t *scn, arc_buf_t *buf, blkptr_t *bp,
+ uint64_t objset, uint64_t object, uint64_t blkid)
+{
+ zbookmark_t czb;
+ uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
+
+ if (zfs_no_scrub_prefetch)
+ return;
+
+ if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_min_txg ||
+ (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE))
+ return;
+
+ SET_BOOKMARK(&czb, objset, object, BP_GET_LEVEL(bp), blkid);
+
+ /*
+ * XXX need to make sure all of these arc_read() prefetches are
+ * done before setting xlateall (similar to dsl_read())
+ */
+ (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, bp,
+ buf, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
+ ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD, &flags, &czb);
+}
+
+static boolean_t
+dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp,
+ const zbookmark_t *zb)
+{
+ /*
+ * We never skip over user/group accounting objects (obj<0)
+ */
+ if (!bookmark_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 (bookmark_is_before(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 pausing
+ * 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);
+}
+
+/*
+ * Return nonzero on i/o error.
+ * Return new buf to write out in *bufp.
+ */
+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_t *zb, dmu_tx_t *tx, arc_buf_t **bufp)
+{
+ 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) {
+ uint32_t flags = ARC_WAIT;
+ int i;
+ blkptr_t *cbp;
+ int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
+
+ err = arc_read_nolock(NULL, dp->dp_spa, bp,
+ arc_getbuf_func, bufp,
+ ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
+ if (err) {
+ scn->scn_phys.scn_errors++;
+ return (err);
+ }
+ for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
+ dsl_scan_prefetch(scn, *bufp, cbp, zb->zb_objset,
+ zb->zb_object, zb->zb_blkid * epb + i);
+ }
+ for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
+ zbookmark_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,
+ *bufp, ds, scn, ostype, tx);
+ }
+ } else if (BP_GET_TYPE(bp) == DMU_OT_USERGROUP_USED) {
+ uint32_t flags = ARC_WAIT;
+
+ err = arc_read_nolock(NULL, dp->dp_spa, bp,
+ arc_getbuf_func, bufp,
+ ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
+ if (err) {
+ scn->scn_phys.scn_errors++;
+ return (err);
+ }
+ } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
+ uint32_t flags = ARC_WAIT;
+ dnode_phys_t *cdnp;
+ int i, j;
+ int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
+
+ err = arc_read_nolock(NULL, dp->dp_spa, bp,
+ arc_getbuf_func, bufp,
+ ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
+ if (err) {
+ scn->scn_phys.scn_errors++;
+ return (err);
+ }
+ for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
+ for (j = 0; j < cdnp->dn_nblkptr; j++) {
+ blkptr_t *cbp = &cdnp->dn_blkptr[j];
+ dsl_scan_prefetch(scn, *bufp, cbp,
+ zb->zb_objset, zb->zb_blkid * epb + i, j);
+ }
+ }
+ for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
+ dsl_scan_visitdnode(scn, ds, ostype,
+ cdnp, *bufp, zb->zb_blkid * epb + i, tx);
+ }
+
+ } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
+ uint32_t flags = ARC_WAIT;
+ objset_phys_t *osp;
+
+ err = arc_read_nolock(NULL, dp->dp_spa, bp,
+ arc_getbuf_func, bufp,
+ ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
+ if (err) {
+ scn->scn_phys.scn_errors++;
+ return (err);
+ }
+
+ osp = (*bufp)->b_data;
+
+ dsl_scan_visitdnode(scn, ds, osp->os_type,
+ &osp->os_meta_dnode, *bufp, DMU_META_DNODE_OBJECT, tx);
+
+ if (OBJSET_BUF_HAS_USERUSED(*bufp)) {
+ /*
+ * We also always visit user/group accounting
+ * objects, and never skip them, even if we are
+ * pausing. This is necessary so that the space
+ * deltas from this txg get integrated.
+ */
+ dsl_scan_visitdnode(scn, ds, osp->os_type,
+ &osp->os_groupused_dnode, *bufp,
+ DMU_GROUPUSED_OBJECT, tx);
+ dsl_scan_visitdnode(scn, ds, osp->os_type,
+ &osp->os_userused_dnode, *bufp,
+ DMU_USERUSED_OBJECT, tx);
+ }
+ }
+
+ return (0);
+}
+
+static void
+dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds,
+ dmu_objset_type_t ostype, dnode_phys_t *dnp, arc_buf_t *buf,
+ uint64_t object, dmu_tx_t *tx)
+{
+ int j;
+
+ for (j = 0; j < dnp->dn_nblkptr; j++) {
+ zbookmark_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, buf, ds, scn, ostype, tx);
+ }
+
+ if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
+ zbookmark_t czb;
+ SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
+ 0, DMU_SPILL_BLKID);
+ dsl_scan_visitbp(&dnp->dn_spill,
+ &czb, dnp, buf, 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_t *zb,
+ dnode_phys_t *dnp, arc_buf_t *pbuf,
+ dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
+ dmu_tx_t *tx)
+{
+ dsl_pool_t *dp = scn->scn_dp;
+ arc_buf_t *buf = NULL;
+ blkptr_t bp_toread = *bp;
+
+ /* ASSERT(pbuf == NULL || arc_released(pbuf)); */
+
+ if (dsl_scan_check_pause(scn, zb))
+ return;
+
+ if (dsl_scan_check_resume(scn, dnp, zb))
+ return;
+
+ if (bp->blk_birth == 0)
+ return;
+
+ scn->scn_visited_this_txg++;
+
+ dprintf_bp(bp,
+ "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx buf=%p bp=%p",
+ ds, ds ? ds->ds_object : 0,
+ zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid,
+ pbuf, bp);
+
+ if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
+ return;
+
+ if (BP_GET_TYPE(bp) != DMU_OT_USERGROUP_USED) {
+ /*
+ * For non-user-accounting blocks, we need to read the
+ * new bp (from a deleted snapshot, found in
+ * check_existing_xlation). If we used the old bp,
+ * pointers inside this block from before we resumed
+ * would be untranslated.
+ *
+ * For user-accounting blocks, we need to read the old
+ * bp, because we will apply the entire space delta to
+ * it (original untranslated -> translations from
+ * deleted snap -> now).
+ */
+ bp_toread = *bp;
+ }
+
+ if (dsl_scan_recurse(scn, ds, ostype, dnp, &bp_toread, zb, tx,
+ &buf) != 0)
+ return;
+
+ /*
+ * If dsl_scan_ddt() has aready 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)) {
+ ASSERT(buf == NULL);
+ return;
+ }
+
+ /*
+ * 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->blk_birth <= scn->scn_phys.scn_cur_max_txg) {
+ scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
+ }
+ if (buf)
+ (void) arc_buf_remove_ref(buf, &buf);
+}
+
+static void
+dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp,
+ dmu_tx_t *tx)
+{
+ zbookmark_t zb;
+
+ SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
+ ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
+ dsl_scan_visitbp(bp, &zb, NULL, NULL,
+ ds, scn, DMU_OST_NONE, tx);
+
+ dprintf_ds(ds, "finished scan%s", "");
+}
+
+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 (scn->scn_phys.scn_state != DSS_SCANNING)
+ return;
+
+ if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
+ if (dsl_dataset_is_snapshot(ds)) {
+ /* Note, scn_cur_{min,max}_txg stays the same. */
+ scn->scn_phys.scn_bookmark.zb_objset =
+ ds->ds_phys->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)ds->ds_phys->ds_next_snap_obj);
+ scn->scn_phys.scn_flags |= DSF_VISIT_DS_AGAIN;
+ } else {
+ SET_BOOKMARK(&scn->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);
+ }
+ } else if (zap_lookup_int_key(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
+ ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
+ VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
+ if (dsl_dataset_is_snapshot(ds)) {
+ /*
+ * 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,
+ ds->ds_phys->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)ds->ds_phys->ds_next_snap_obj);
+ } else {
+ zfs_dbgmsg("destroying ds %llu; in queue; removing",
+ (u_longlong_t)ds->ds_object);
+ }
+ } else {
+ zfs_dbgmsg("destroying ds %llu; ignoring",
+ (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);
+}
+
+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 (scn->scn_phys.scn_state != DSS_SCANNING)
+ return;
+
+ ASSERT(ds->ds_phys->ds_prev_snap_obj != 0);
+
+ if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
+ scn->scn_phys.scn_bookmark.zb_objset =
+ ds->ds_phys->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)ds->ds_phys->ds_prev_snap_obj);
+ } else 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,
+ ds->ds_phys->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)ds->ds_phys->ds_prev_snap_obj);
+ }
+ dsl_scan_sync_state(scn, tx);
+}
+
+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 (scn->scn_phys.scn_state != DSS_SCANNING)
+ return;
+
+ if (scn->scn_phys.scn_bookmark.zb_objset == ds1->ds_object) {
+ scn->scn_phys.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->scn_phys.scn_bookmark.zb_objset == ds2->ds_object) {
+ scn->scn_phys.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);
+ }
+
+ if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
+ ds1->ds_object, &mintxg) == 0) {
+ int err;
+
+ ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
+ ASSERT3U(mintxg, ==, ds2->ds_phys->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);
+ } else if (zap_lookup_int_key(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg) == 0) {
+ ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
+ ASSERT3U(mintxg, ==, ds2->ds_phys->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);
+}
+
+struct enqueue_clones_arg {
+ dmu_tx_t *tx;
+ uint64_t originobj;
+};
+
+/* ARGSUSED */
+static int
+enqueue_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
+{
+ struct enqueue_clones_arg *eca = arg;
+ dsl_dataset_t *ds;
+ int err;
+ dsl_pool_t *dp = spa->spa_dsl_pool;
+ dsl_scan_t *scn = dp->dp_scan;
+
+ err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
+ if (err)
+ return (err);
+
+ if (ds->ds_dir->dd_phys->dd_origin_obj == eca->originobj) {
+ while (ds->ds_phys->ds_prev_snap_obj != eca->originobj) {
+ dsl_dataset_t *prev;
+ err = dsl_dataset_hold_obj(dp,
+ ds->ds_phys->ds_prev_snap_obj, FTAG, &prev);
+
+ dsl_dataset_rele(ds, FTAG);
+ if (err)
+ return (err);
+ ds = prev;
+ }
+ VERIFY(zap_add_int_key(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, ds->ds_object,
+ ds->ds_phys->ds_prev_snap_txg, eca->tx) == 0);
+ }
+ 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;
+ objset_t *os;
+
+ VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
+
+ if (dmu_objset_from_ds(ds, &os))
+ 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. 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_SCAN_IS_SCRUB_RESILVER(scn) && !dsl_dataset_is_snapshot(ds))
+ dsl_scan_zil(dp, &os->os_zil_header);
+
+ /*
+ * Iterate over the bps in this ds.
+ */
+ dmu_buf_will_dirty(ds->ds_dbuf, tx);
+ dsl_scan_visit_rootbp(scn, ds, &ds->ds_phys->ds_bp, tx);
+
+ char *dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_SLEEP);
+ dsl_dataset_name(ds, dsname);
+ zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
+ "pausing=%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_pausing);
+ kmem_free(dsname, ZFS_MAXNAMELEN);
+
+ if (scn->scn_pausing)
+ 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;
+ VERIFY(zap_add_int_key(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, ds->ds_object,
+ scn->scn_phys.scn_cur_max_txg, tx) == 0);
+ goto out;
+ }
+
+ /*
+ * Add descendent datasets to work queue.
+ */
+ if (ds->ds_phys->ds_next_snap_obj != 0) {
+ VERIFY(zap_add_int_key(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, ds->ds_phys->ds_next_snap_obj,
+ ds->ds_phys->ds_creation_txg, tx) == 0);
+ }
+ if (ds->ds_phys->ds_num_children > 1) {
+ boolean_t usenext = B_FALSE;
+ if (ds->ds_phys->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,
+ ds->ds_phys->ds_next_clones_obj, &count);
+ if (err == 0 &&
+ count == ds->ds_phys->ds_num_children - 1)
+ usenext = B_TRUE;
+ }
+
+ if (usenext) {
+ VERIFY(zap_join_key(dp->dp_meta_objset,
+ ds->ds_phys->ds_next_clones_obj,
+ scn->scn_phys.scn_queue_obj,
+ ds->ds_phys->ds_creation_txg, tx) == 0);
+ } else {
+ struct enqueue_clones_arg eca;
+ eca.tx = tx;
+ eca.originobj = ds->ds_object;
+
+ (void) dmu_objset_find_spa(ds->ds_dir->dd_pool->dp_spa,
+ NULL, enqueue_clones_cb, &eca, DS_FIND_CHILDREN);
+ }
+ }
+
+out:
+ dsl_dataset_rele(ds, FTAG);
+}
+
+/* ARGSUSED */
+static int
+enqueue_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
+{
+ dmu_tx_t *tx = arg;
+ dsl_dataset_t *ds;
+ int err;
+ dsl_pool_t *dp = spa->spa_dsl_pool;
+ dsl_scan_t *scn = dp->dp_scan;
+
+ err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
+ if (err)
+ return (err);
+
+ while (ds->ds_phys->ds_prev_snap_obj != 0) {
+ dsl_dataset_t *prev;
+ err = dsl_dataset_hold_obj(dp, ds->ds_phys->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 (prev->ds_phys->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;
+ }
+
+ VERIFY(zap_add_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
+ ds->ds_object, ds->ds_phys->ds_prev_snap_txg, tx) == 0);
+ dsl_dataset_rele(ds, FTAG);
+ return (0);
+}
+
+/*
+ * 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 = { 0 };
+ int error;
+ uint64_t n = 0;
+
+ 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_pause(scn, NULL))
+ break;
+ }
+
+ zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
+ (longlong_t)n, (int)scn->scn_phys.scn_ddt_class_max,
+ (int)scn->scn_pausing);
+
+ ASSERT(error == 0 || error == ENOENT);
+ ASSERT(error != ENOENT ||
+ ddb->ddb_class > scn->scn_phys.scn_ddt_class_max);
+}
+
+/* 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_t zb = { 0 };
+
+ if (scn->scn_phys.scn_state != DSS_SCANNING)
+ return;
+
+ for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
+ if (ddp->ddp_phys_birth == 0 ||
+ ddp->ddp_phys_birth > scn->scn_phys.scn_cur_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);
+ }
+}
+
+static void
+dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
+{
+ dsl_pool_t *dp = scn->scn_dp;
+ zap_cursor_t zc;
+ zap_attribute_t za;
+
+ 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_pausing)
+ 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_pausing)
+ return;
+
+ if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
+ VERIFY(0 == dmu_objset_find_spa(dp->dp_spa,
+ NULL, enqueue_cb, tx, DS_FIND_CHILDREN));
+ } else {
+ dsl_scan_visitds(scn,
+ dp->dp_origin_snap->ds_object, tx);
+ }
+ ASSERT(!scn->scn_pausing);
+ } else if (scn->scn_phys.scn_bookmark.zb_objset !=
+ ZB_DESTROYED_OBJSET) {
+ /*
+ * If we were paused, continue from here. Note if the
+ * ds we were paused on was deleted, the zb_objset may
+ * be -1, so we will skip this and find a new objset
+ * below.
+ */
+ dsl_scan_visitds(scn, scn->scn_phys.scn_bookmark.zb_objset, tx);
+ if (scn->scn_pausing)
+ return;
+ }
+
+ /*
+ * In case we were paused 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_t));
+
+ /* keep pulling things out of the zap-object-as-queue */
+ while (zap_cursor_init(&zc, dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj),
+ zap_cursor_retrieve(&zc, &za) == 0) {
+ dsl_dataset_t *ds;
+ uint64_t dsobj;
+
+ dsobj = strtonum(za.za_name, NULL);
+ VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
+ scn->scn_phys.scn_queue_obj, dsobj, tx));
+
+ /* Set up min/max txg */
+ VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
+ if (za.za_first_integer != 0) {
+ scn->scn_phys.scn_cur_min_txg =
+ MAX(scn->scn_phys.scn_min_txg,
+ za.za_first_integer);
+ } else {
+ scn->scn_phys.scn_cur_min_txg =
+ MAX(scn->scn_phys.scn_min_txg,
+ ds->ds_phys->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);
+ zap_cursor_fini(&zc);
+ if (scn->scn_pausing)
+ return;
+ }
+ zap_cursor_fini(&zc);
+}
+
+static int
+dsl_scan_free_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
+{
+ dsl_scan_t *scn = arg;
+ uint64_t elapsed_nanosecs;
+
+ elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
+
+ if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
+ (elapsed_nanosecs / MICROSEC > zfs_free_min_time_ms &&
+ txg_sync_waiting(scn->scn_dp)) ||
+ spa_shutting_down(scn->scn_dp->dp_spa))
+ return (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);
+}
+
+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 (scn->scn_phys.scn_state == DSS_SCANNING)
+ 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);
+}
+
+void
+dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
+{
+ dsl_scan_t *scn = dp->dp_scan;
+ spa_t *spa = dp->dp_spa;
+ int err;
+
+ /*
+ * 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).
+ */
+ if (scn->scn_restart_txg != 0 &&
+ scn->scn_restart_txg <= tx->tx_txg) {
+ 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, tx->tx_txg);
+ dsl_scan_setup_sync(scn, &func, tx);
+ }
+
+ if (!dsl_scan_active(scn) ||
+ spa_sync_pass(dp->dp_spa) > 1)
+ return;
+
+ scn->scn_visited_this_txg = 0;
+ scn->scn_pausing = B_FALSE;
+ scn->scn_sync_start_time = gethrtime();
+ spa->spa_scrub_active = B_TRUE;
+
+ /*
+ * First process the free list. If we pause the free, don't do
+ * any scanning. This ensures that there is no free list when
+ * we are scanning, so the scan code doesn't have to worry about
+ * traversing it.
+ */
+ if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
+ scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
+ NULL, ZIO_FLAG_MUSTSUCCEED);
+ err = bpobj_iterate(&dp->dp_free_bpobj,
+ dsl_scan_free_cb, scn, tx);
+ VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
+ if (scn->scn_visited_this_txg) {
+ zfs_dbgmsg("freed %llu blocks in %llums from "
+ "free_bpobj txg %llu",
+ (longlong_t)scn->scn_visited_this_txg,
+ (longlong_t)
+ (gethrtime() - scn->scn_sync_start_time) / MICROSEC,
+ (longlong_t)tx->tx_txg);
+ scn->scn_visited_this_txg = 0;
+ /*
+ * Re-sync the ddt so that we can further modify
+ * it when doing bprewrite.
+ */
+ ddt_sync(spa, tx->tx_txg);
+ }
+ if (err == ERESTART)
+ return;
+ }
+
+ if (scn->scn_phys.scn_state != DSS_SCANNING)
+ return;
+
+ if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
+ scn->scn_phys.scn_ddt_class_max) {
+ zfs_dbgmsg("doing scan sync txg %llu; "
+ "ddt bm=%llu/%llu/%llu/%llx",
+ (longlong_t)tx->tx_txg,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
+ (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
+ ASSERT(scn->scn_phys.scn_bookmark.zb_objset == 0);
+ ASSERT(scn->scn_phys.scn_bookmark.zb_object == 0);
+ ASSERT(scn->scn_phys.scn_bookmark.zb_level == 0);
+ ASSERT(scn->scn_phys.scn_bookmark.zb_blkid == 0);
+ } else {
+ zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
+ (longlong_t)tx->tx_txg,
+ (longlong_t)scn->scn_phys.scn_bookmark.zb_objset,
+ (longlong_t)scn->scn_phys.scn_bookmark.zb_object,
+ (longlong_t)scn->scn_phys.scn_bookmark.zb_level,
+ (longlong_t)scn->scn_phys.scn_bookmark.zb_blkid);
+ }
+
+ scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
+ NULL, ZIO_FLAG_CANFAIL);
+ dsl_scan_visit(scn, tx);
+ (void) zio_wait(scn->scn_zio_root);
+ scn->scn_zio_root = NULL;
+
+ zfs_dbgmsg("visited %llu blocks in %llums",
+ (longlong_t)scn->scn_visited_this_txg,
+ (longlong_t)(gethrtime() - scn->scn_sync_start_time) / MICROSEC);
+
+ if (!scn->scn_pausing) {
+ /* finished with scan. */
+ zfs_dbgmsg("finished scan txg %llu", (longlong_t)tx->tx_txg);
+ dsl_scan_done(scn, B_TRUE, tx);
+ }
+
+ if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
+ mutex_enter(&spa->spa_scrub_lock);
+ while (spa->spa_scrub_inflight > 0) {
+ cv_wait(&spa->spa_scrub_io_cv,
+ &spa->spa_scrub_lock);
+ }
+ mutex_exit(&spa->spa_scrub_lock);
+ }
+
+ dsl_scan_sync_state(scn, tx);
+}
+
+/*
+ * This will 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", txg);
+}
+
+boolean_t
+dsl_scan_resilvering(dsl_pool_t *dp)
+{
+ return (dp->dp_scan->scn_phys.scn_state == DSS_SCANNING &&
+ dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER);
+}
+
+/*
+ * scrub consumers
+ */
+
+static void
+count_block(zfs_all_blkstats_t *zab, const blkptr_t *bp)
+{
+ int i;
+
+ /*
+ * If we resume after a reboot, zab will be NULL; don't record
+ * incomplete stats in that case.
+ */
+ if (zab == NULL)
+ return;
+
+ 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;
+ 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;
+ }
+ }
+}
+
+static void
+dsl_scan_scrub_done(zio_t *zio)
+{
+ spa_t *spa = zio->io_spa;
+
+ zio_data_buf_free(zio->io_data, zio->io_size);
+
+ mutex_enter(&spa->spa_scrub_lock);
+ spa->spa_scrub_inflight--;
+ cv_broadcast(&spa->spa_scrub_io_cv);
+
+ if (zio->io_error && (zio->io_error != ECKSUM ||
+ !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) {
+ spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors++;
+ }
+ mutex_exit(&spa->spa_scrub_lock);
+}
+
+static int
+dsl_scan_scrub_cb(dsl_pool_t *dp,
+ const blkptr_t *bp, const zbookmark_t *zb)
+{
+ dsl_scan_t *scn = dp->dp_scan;
+ size_t size = BP_GET_PSIZE(bp);
+ spa_t *spa = dp->dp_spa;
+ uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
+ boolean_t needs_io;
+ int zio_flags = ZIO_FLAG_SCAN_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL;
+ int zio_priority;
+ int scan_delay = 0;
+
+ if (phys_birth <= scn->scn_phys.scn_min_txg ||
+ phys_birth >= scn->scn_phys.scn_max_txg)
+ return (0);
+
+ count_block(dp->dp_blkstats, bp);
+
+ ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn));
+ if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) {
+ zio_flags |= ZIO_FLAG_SCRUB;
+ zio_priority = ZIO_PRIORITY_SCRUB;
+ needs_io = B_TRUE;
+ scan_delay = zfs_scrub_delay;
+ } else if (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) {
+ zio_flags |= ZIO_FLAG_RESILVER;
+ zio_priority = ZIO_PRIORITY_RESILVER;
+ needs_io = B_FALSE;
+ scan_delay = zfs_resilver_delay;
+ }
+
+ /* 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++) {
+ vdev_t *vd = vdev_lookup_top(spa,
+ DVA_GET_VDEV(&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(&bp->blk_dva[d]);
+ spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
+
+ /* if it's a resilver, this may not be in the target range */
+ if (!needs_io) {
+ if (DVA_GET_GANG(&bp->blk_dva[d])) {
+ /*
+ * 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.
+ */
+ needs_io = B_TRUE;
+ } else {
+ needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
+ phys_birth, 1);
+ }
+ }
+ }
+
+ if (needs_io && !zfs_no_scrub_io) {
+ vdev_t *rvd = spa->spa_root_vdev;
+ uint64_t maxinflight = rvd->vdev_children * zfs_top_maxinflight;
+ void *data = zio_data_buf_alloc(size);
+
+ mutex_enter(&spa->spa_scrub_lock);
+ while (spa->spa_scrub_inflight >= maxinflight)
+ cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
+ spa->spa_scrub_inflight++;
+ mutex_exit(&spa->spa_scrub_lock);
+
+ /*
+ * If we're seeing recent (zfs_scan_idle) "important" I/Os
+ * then throttle our workload to limit the impact of a scan.
+ */
+ if (ddi_get_lbolt64() - spa->spa_last_io <= zfs_scan_idle)
+ delay(scan_delay);
+
+ zio_nowait(zio_read(NULL, spa, bp, data, size,
+ dsl_scan_scrub_done, NULL, zio_priority,
+ zio_flags, zb));
+ }
+
+ /* do not relocate this block */
+ return (0);
+}
+
+int
+dsl_scan(dsl_pool_t *dp, pool_scan_func_t func)
+{
+ spa_t *spa = dp->dp_spa;
+
+ /*
+ * 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);
+
+ return (dsl_sync_task_do(dp, dsl_scan_setup_check,
+ dsl_scan_setup_sync, dp->dp_scan, &func, 0));
+}