1 files changed, 929 insertions, 0 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scrub.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scrub.c
new file mode 100644
index 0000000..5f675b7
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scrub.c
@@ -0,0 +1,929 @@
+/*
+ * 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 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#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>
+
+typedef int (scrub_cb_t)(dsl_pool_t *, const blkptr_t *, const zbookmark_t *);
+
+static scrub_cb_t dsl_pool_scrub_clean_cb;
+static dsl_syncfunc_t dsl_pool_scrub_cancel_sync;
+
+int zfs_scrub_min_time = 1; /* scrub for at least 1 sec each txg */
+int zfs_resilver_min_time = 3; /* resilver for at least 3 sec each txg */
+boolean_t zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */
+
+extern int zfs_txg_timeout;
+
+static scrub_cb_t *scrub_funcs[SCRUB_FUNC_NUMFUNCS] = {
+	NULL,
+	dsl_pool_scrub_clean_cb
+};
+
+#define	SET_BOOKMARK(zb, objset, object, level, blkid)  \
+{                                                       \
+	(zb)->zb_objset = objset;                       \
+	(zb)->zb_object = object;                       \
+	(zb)->zb_level = level;                         \
+	(zb)->zb_blkid = blkid;                         \
+}
+
+/* ARGSUSED */
+static void
+dsl_pool_scrub_setup_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+	dsl_pool_t *dp = arg1;
+	enum scrub_func *funcp = arg2;
+	dmu_object_type_t ot = 0;
+	boolean_t complete = B_FALSE;
+
+	dsl_pool_scrub_cancel_sync(dp, &complete, cr, tx);
+
+	ASSERT(dp->dp_scrub_func == SCRUB_FUNC_NONE);
+	ASSERT(*funcp > SCRUB_FUNC_NONE);
+	ASSERT(*funcp < SCRUB_FUNC_NUMFUNCS);
+
+	dp->dp_scrub_min_txg = 0;
+	dp->dp_scrub_max_txg = tx->tx_txg;
+
+	if (*funcp == SCRUB_FUNC_CLEAN) {
+		vdev_t *rvd = dp->dp_spa->spa_root_vdev;
+
+		/* rewrite all disk labels */
+		vdev_config_dirty(rvd);
+
+		if (vdev_resilver_needed(rvd,
+		    &dp->dp_scrub_min_txg, &dp->dp_scrub_max_txg)) {
+			spa_event_notify(dp->dp_spa, NULL,
+			    ESC_ZFS_RESILVER_START);
+			dp->dp_scrub_max_txg = MIN(dp->dp_scrub_max_txg,
+			    tx->tx_txg);
+		}
+
+		/* zero out the scrub stats in all vdev_stat_t's */
+		vdev_scrub_stat_update(rvd,
+		    dp->dp_scrub_min_txg ? POOL_SCRUB_RESILVER :
+		    POOL_SCRUB_EVERYTHING, B_FALSE);
+
+		dp->dp_spa->spa_scrub_started = B_TRUE;
+	}
+
+	/* back to the generic stuff */
+
+	if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB)
+		ot = DMU_OT_ZAP_OTHER;
+
+	dp->dp_scrub_func = *funcp;
+	dp->dp_scrub_queue_obj = zap_create(dp->dp_meta_objset,
+	    ot ? ot : DMU_OT_SCRUB_QUEUE, DMU_OT_NONE, 0, tx);
+	bzero(&dp->dp_scrub_bookmark, sizeof (zbookmark_t));
+	dp->dp_scrub_restart = B_FALSE;
+	dp->dp_spa->spa_scrub_errors = 0;
+
+	VERIFY(0 == zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_FUNC, sizeof (uint32_t), 1,
+	    &dp->dp_scrub_func, tx));
+	VERIFY(0 == zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_QUEUE, sizeof (uint64_t), 1,
+	    &dp->dp_scrub_queue_obj, tx));
+	VERIFY(0 == zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_MIN_TXG, sizeof (uint64_t), 1,
+	    &dp->dp_scrub_min_txg, tx));
+	VERIFY(0 == zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_MAX_TXG, sizeof (uint64_t), 1,
+	    &dp->dp_scrub_max_txg, tx));
+	VERIFY(0 == zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_BOOKMARK, sizeof (uint64_t), 4,
+	    &dp->dp_scrub_bookmark, tx));
+	VERIFY(0 == zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_ERRORS, sizeof (uint64_t), 1,
+	    &dp->dp_spa->spa_scrub_errors, tx));
+
+	spa_history_internal_log(LOG_POOL_SCRUB, dp->dp_spa, tx, cr,
+	    "func=%u mintxg=%llu maxtxg=%llu",
+	    *funcp, dp->dp_scrub_min_txg, dp->dp_scrub_max_txg);
+}
+
+int
+dsl_pool_scrub_setup(dsl_pool_t *dp, enum scrub_func func)
+{
+	return (dsl_sync_task_do(dp, NULL,
+	    dsl_pool_scrub_setup_sync, dp, &func, 0));
+}
+
+/* ARGSUSED */
+static void
+dsl_pool_scrub_cancel_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+{
+	dsl_pool_t *dp = arg1;
+	boolean_t *completep = arg2;
+
+	if (dp->dp_scrub_func == SCRUB_FUNC_NONE)
+		return;
+
+	mutex_enter(&dp->dp_scrub_cancel_lock);
+
+	if (dp->dp_scrub_restart) {
+		dp->dp_scrub_restart = B_FALSE;
+		*completep = B_FALSE;
+	}
+
+	/* XXX this is scrub-clean specific */
+	mutex_enter(&dp->dp_spa->spa_scrub_lock);
+	while (dp->dp_spa->spa_scrub_inflight > 0) {
+		cv_wait(&dp->dp_spa->spa_scrub_io_cv,
+		    &dp->dp_spa->spa_scrub_lock);
+	}
+	mutex_exit(&dp->dp_spa->spa_scrub_lock);
+	dp->dp_spa->spa_scrub_started = B_FALSE;
+	dp->dp_spa->spa_scrub_active = B_FALSE;
+
+	dp->dp_scrub_func = SCRUB_FUNC_NONE;
+	VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
+	    dp->dp_scrub_queue_obj, tx));
+	dp->dp_scrub_queue_obj = 0;
+	bzero(&dp->dp_scrub_bookmark, sizeof (zbookmark_t));
+
+	VERIFY(0 == zap_remove(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_QUEUE, tx));
+	VERIFY(0 == zap_remove(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_MIN_TXG, tx));
+	VERIFY(0 == zap_remove(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_MAX_TXG, tx));
+	VERIFY(0 == zap_remove(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_BOOKMARK, tx));
+	VERIFY(0 == zap_remove(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_FUNC, tx));
+	VERIFY(0 == zap_remove(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_ERRORS, tx));
+
+	spa_history_internal_log(LOG_POOL_SCRUB_DONE, dp->dp_spa, tx, cr,
+	    "complete=%u", *completep);
+
+	/* below is scrub-clean specific */
+	vdev_scrub_stat_update(dp->dp_spa->spa_root_vdev, POOL_SCRUB_NONE,
+	    *completep);
+	/*
+	 * If the scrub/resilver completed, update all DTLs to reflect this.
+	 * Whether it succeeded or not, vacate all temporary scrub DTLs.
+	 */
+	vdev_dtl_reassess(dp->dp_spa->spa_root_vdev, tx->tx_txg,
+	    *completep ? dp->dp_scrub_max_txg : 0, B_TRUE);
+	if (dp->dp_scrub_min_txg && *completep)
+		spa_event_notify(dp->dp_spa, NULL, ESC_ZFS_RESILVER_FINISH);
+	spa_errlog_rotate(dp->dp_spa);
+
+	/*
+	 * We may have finished replacing a device.
+	 * Let the async thread assess this and handle the detach.
+	 */
+	spa_async_request(dp->dp_spa, SPA_ASYNC_RESILVER_DONE);
+
+	dp->dp_scrub_min_txg = dp->dp_scrub_max_txg = 0;
+	mutex_exit(&dp->dp_scrub_cancel_lock);
+}
+
+int
+dsl_pool_scrub_cancel(dsl_pool_t *dp)
+{
+	boolean_t complete = B_FALSE;
+
+	return (dsl_sync_task_do(dp, NULL,
+	    dsl_pool_scrub_cancel_sync, dp, &complete, 3));
+}
+
+int
+dsl_free(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp,
+    zio_done_func_t *done, void *private, uint32_t arc_flags)
+{
+	/*
+	 * This function will be used by bp-rewrite wad to intercept frees.
+	 */
+	return (arc_free(pio, dp->dp_spa, txg, (blkptr_t *)bpp,
+	    done, private, arc_flags));
+}
+
+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(dnode_phys_t *dnp, const zbookmark_t *zb1,
+    const zbookmark_t *zb2)
+{
+	uint64_t zb1nextL0, zb2thisobj;
+
+	ASSERT(zb1->zb_objset == zb2->zb_objset);
+	ASSERT(zb1->zb_object != -1ULL);
+	ASSERT(zb2->zb_level == 0);
+
+	/*
+	 * A bookmark in the deadlist is considered to be after
+	 * everything else.
+	 */
+	if (zb2->zb_object == -1ULL)
+		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 == 0) {
+		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 == 0)
+		return (B_FALSE);
+	return (zb1nextL0 <= zb2->zb_blkid);
+}
+
+static boolean_t
+scrub_pause(dsl_pool_t *dp, const zbookmark_t *zb)
+{
+	int elapsed_ticks;
+	int mintime;
+
+	if (dp->dp_scrub_pausing)
+		return (B_TRUE); /* we're already pausing */
+
+	if (!bookmark_is_zero(&dp->dp_scrub_bookmark))
+		return (B_FALSE); /* we're resuming */
+
+	/* We only know how to resume from level-0 blocks. */
+	if (zb->zb_level != 0)
+		return (B_FALSE);
+
+	mintime = dp->dp_scrub_isresilver ? zfs_resilver_min_time :
+	    zfs_scrub_min_time;
+	elapsed_ticks = lbolt64 - dp->dp_scrub_start_time;
+	if (elapsed_ticks > hz * zfs_txg_timeout ||
+	    (elapsed_ticks > hz * mintime && txg_sync_waiting(dp))) {
+		dprintf("pausing 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);
+		dp->dp_scrub_pausing = B_TRUE;
+		dp->dp_scrub_bookmark = *zb;
+		return (B_TRUE);
+	}
+	return (B_FALSE);
+}
+
+typedef struct zil_traverse_arg {
+	dsl_pool_t	*zta_dp;
+	zil_header_t	*zta_zh;
+} zil_traverse_arg_t;
+
+/* ARGSUSED */
+static void
+traverse_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
+{
+	zil_traverse_arg_t *zta = arg;
+	dsl_pool_t *dp = zta->zta_dp;
+	zil_header_t *zh = zta->zta_zh;
+	zbookmark_t zb;
+
+	if (bp->blk_birth <= dp->dp_scrub_min_txg)
+		return;
+
+	if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(dp->dp_spa))
+		return;
+
+	zb.zb_objset = zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET];
+	zb.zb_object = 0;
+	zb.zb_level = -1;
+	zb.zb_blkid = bp->blk_cksum.zc_word[ZIL_ZC_SEQ];
+	VERIFY(0 == scrub_funcs[dp->dp_scrub_func](dp, bp, &zb));
+}
+
+/* ARGSUSED */
+static void
+traverse_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
+{
+	if (lrc->lrc_txtype == TX_WRITE) {
+		zil_traverse_arg_t *zta = arg;
+		dsl_pool_t *dp = zta->zta_dp;
+		zil_header_t *zh = zta->zta_zh;
+		lr_write_t *lr = (lr_write_t *)lrc;
+		blkptr_t *bp = &lr->lr_blkptr;
+		zbookmark_t zb;
+
+		if (bp->blk_birth <= dp->dp_scrub_min_txg)
+			return;
+
+		if (claim_txg == 0 || bp->blk_birth < claim_txg)
+			return;
+
+		zb.zb_objset = zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET];
+		zb.zb_object = lr->lr_foid;
+		zb.zb_level = BP_GET_LEVEL(bp);
+		zb.zb_blkid = lr->lr_offset / BP_GET_LSIZE(bp);
+		VERIFY(0 == scrub_funcs[dp->dp_scrub_func](dp, bp, &zb));
+	}
+}
+
+static void
+traverse_zil(dsl_pool_t *dp, zil_header_t *zh)
+{
+	uint64_t claim_txg = zh->zh_claim_txg;
+	zil_traverse_arg_t zta = { 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_mode & FWRITE))
+		return;
+
+	zilog = zil_alloc(dp->dp_meta_objset, zh);
+
+	(void) zil_parse(zilog, traverse_zil_block, traverse_zil_record, &zta,
+	    claim_txg);
+
+	zil_free(zilog);
+}
+
+static void
+scrub_visitbp(dsl_pool_t *dp, dnode_phys_t *dnp,
+    arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb)
+{
+	int err;
+	arc_buf_t *buf = NULL;
+
+	if (bp->blk_birth == 0)
+		return;
+
+	if (bp->blk_birth <= dp->dp_scrub_min_txg)
+		return;
+
+	if (scrub_pause(dp, zb))
+		return;
+
+	if (!bookmark_is_zero(&dp->dp_scrub_bookmark)) {
+		/*
+		 * If we already visited this bp & everything below (in
+		 * a prior txg), don't bother doing it again.
+		 */
+		if (bookmark_is_before(dnp, zb, &dp->dp_scrub_bookmark))
+			return;
+
+		/*
+		 * 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, &dp->dp_scrub_bookmark, sizeof (*zb)) == 0 ||
+		    zb->zb_object > dp->dp_scrub_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(&dp->dp_scrub_bookmark, sizeof (*zb));
+		}
+	}
+
+	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(NULL, dp->dp_spa, bp, pbuf,
+		    arc_getbuf_func, &buf,
+		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
+		if (err) {
+			mutex_enter(&dp->dp_spa->spa_scrub_lock);
+			dp->dp_spa->spa_scrub_errors++;
+			mutex_exit(&dp->dp_spa->spa_scrub_lock);
+			return;
+		}
+		cbp = buf->b_data;
+
+		for (i = 0; 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);
+			scrub_visitbp(dp, dnp, buf, cbp, &czb);
+		}
+	} else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
+		uint32_t flags = ARC_WAIT;
+		dnode_phys_t *child_dnp;
+		int i, j;
+		int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
+
+		err = arc_read(NULL, dp->dp_spa, bp, pbuf,
+		    arc_getbuf_func, &buf,
+		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
+		if (err) {
+			mutex_enter(&dp->dp_spa->spa_scrub_lock);
+			dp->dp_spa->spa_scrub_errors++;
+			mutex_exit(&dp->dp_spa->spa_scrub_lock);
+			return;
+		}
+		child_dnp = buf->b_data;
+
+		for (i = 0; i < epb; i++, child_dnp++) {
+			for (j = 0; j < child_dnp->dn_nblkptr; j++) {
+				zbookmark_t czb;
+
+				SET_BOOKMARK(&czb, zb->zb_objset,
+				    zb->zb_blkid * epb + i,
+				    child_dnp->dn_nlevels - 1, j);
+				scrub_visitbp(dp, child_dnp, buf,
+				    &child_dnp->dn_blkptr[j], &czb);
+			}
+		}
+	} else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
+		uint32_t flags = ARC_WAIT;
+		objset_phys_t *osp;
+		int j;
+
+		err = arc_read_nolock(NULL, dp->dp_spa, bp,
+		    arc_getbuf_func, &buf,
+		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
+		if (err) {
+			mutex_enter(&dp->dp_spa->spa_scrub_lock);
+			dp->dp_spa->spa_scrub_errors++;
+			mutex_exit(&dp->dp_spa->spa_scrub_lock);
+			return;
+		}
+
+		osp = buf->b_data;
+
+		traverse_zil(dp, &osp->os_zil_header);
+
+		for (j = 0; j < osp->os_meta_dnode.dn_nblkptr; j++) {
+			zbookmark_t czb;
+
+			SET_BOOKMARK(&czb, zb->zb_objset, 0,
+			    osp->os_meta_dnode.dn_nlevels - 1, j);
+			scrub_visitbp(dp, &osp->os_meta_dnode, buf,
+			    &osp->os_meta_dnode.dn_blkptr[j], &czb);
+		}
+	}
+
+	(void) scrub_funcs[dp->dp_scrub_func](dp, bp, zb);
+	if (buf)
+		(void) arc_buf_remove_ref(buf, &buf);
+}
+
+static void
+scrub_visit_rootbp(dsl_pool_t *dp, dsl_dataset_t *ds, blkptr_t *bp)
+{
+	zbookmark_t zb;
+
+	SET_BOOKMARK(&zb, ds ? ds->ds_object : 0, 0, -1, 0);
+	scrub_visitbp(dp, NULL, NULL, bp, &zb);
+}
+
+void
+dsl_pool_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx)
+{
+	dsl_pool_t *dp = ds->ds_dir->dd_pool;
+
+	if (dp->dp_scrub_func == SCRUB_FUNC_NONE)
+		return;
+
+	if (dp->dp_scrub_bookmark.zb_objset == ds->ds_object) {
+		SET_BOOKMARK(&dp->dp_scrub_bookmark, -1, 0, 0, 0);
+	} else if (zap_remove_int(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+	    ds->ds_object, tx) != 0) {
+		return;
+	}
+
+	if (ds->ds_phys->ds_next_snap_obj != 0) {
+		VERIFY(zap_add_int(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+		    ds->ds_phys->ds_next_snap_obj, tx) == 0);
+	}
+	ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
+}
+
+void
+dsl_pool_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx)
+{
+	dsl_pool_t *dp = ds->ds_dir->dd_pool;
+
+	if (dp->dp_scrub_func == SCRUB_FUNC_NONE)
+		return;
+
+	ASSERT(ds->ds_phys->ds_prev_snap_obj != 0);
+
+	if (dp->dp_scrub_bookmark.zb_objset == ds->ds_object) {
+		dp->dp_scrub_bookmark.zb_objset =
+		    ds->ds_phys->ds_prev_snap_obj;
+	} else if (zap_remove_int(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+	    ds->ds_object, tx) == 0) {
+		VERIFY(zap_add_int(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+		    ds->ds_phys->ds_prev_snap_obj, tx) == 0);
+	}
+}
+
+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;
+
+	err = dsl_dataset_hold_obj(spa->spa_dsl_pool, dsobj, FTAG, &ds);
+	if (err)
+		return (err);
+	dp = ds->ds_dir->dd_pool;
+
+	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(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+		    ds->ds_object, eca->tx) == 0);
+	}
+	dsl_dataset_rele(ds, FTAG);
+	return (0);
+}
+
+static void
+scrub_visitds(dsl_pool_t *dp, uint64_t dsobj, dmu_tx_t *tx)
+{
+	dsl_dataset_t *ds;
+	uint64_t min_txg_save;
+
+	VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
+
+	/*
+	 * Iterate over the bps in this ds.
+	 */
+	min_txg_save = dp->dp_scrub_min_txg;
+	dp->dp_scrub_min_txg =
+	    MAX(dp->dp_scrub_min_txg, ds->ds_phys->ds_prev_snap_txg);
+	scrub_visit_rootbp(dp, ds, &ds->ds_phys->ds_bp);
+	dp->dp_scrub_min_txg = min_txg_save;
+
+	if (dp->dp_scrub_pausing)
+		goto out;
+
+	/*
+	 * Add descendent datasets to work queue.
+	 */
+	if (ds->ds_phys->ds_next_snap_obj != 0) {
+		VERIFY(zap_add_int(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+		    ds->ds_phys->ds_next_snap_obj, tx) == 0);
+	}
+	if (ds->ds_phys->ds_num_children > 1) {
+		if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
+			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);
+		} else {
+			VERIFY(zap_join(dp->dp_meta_objset,
+			    ds->ds_phys->ds_next_clones_obj,
+			    dp->dp_scrub_queue_obj, tx) == 0);
+		}
+	}
+
+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;
+
+	err = dsl_dataset_hold_obj(spa->spa_dsl_pool, dsobj, FTAG, &ds);
+	if (err)
+		return (err);
+
+	dp = ds->ds_dir->dd_pool;
+
+	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(dp->dp_meta_objset, dp->dp_scrub_queue_obj,
+	    ds->ds_object, tx) == 0);
+	dsl_dataset_rele(ds, FTAG);
+	return (0);
+}
+
+void
+dsl_pool_scrub_sync(dsl_pool_t *dp, dmu_tx_t *tx)
+{
+	zap_cursor_t zc;
+	zap_attribute_t za;
+	boolean_t complete = B_TRUE;
+
+	if (dp->dp_scrub_func == SCRUB_FUNC_NONE)
+		return;
+
+	/* If the spa is not fully loaded, don't bother. */
+	if (dp->dp_spa->spa_load_state != SPA_LOAD_NONE)
+		return;
+
+	if (dp->dp_scrub_restart) {
+		enum scrub_func func = dp->dp_scrub_func;
+		dp->dp_scrub_restart = B_FALSE;
+		dsl_pool_scrub_setup_sync(dp, &func, kcred, tx);
+	}
+
+	if (dp->dp_spa->spa_root_vdev->vdev_stat.vs_scrub_type == 0) {
+		/*
+		 * We must have resumed after rebooting; reset the vdev
+		 * stats to know that we're doing a scrub (although it
+		 * will think we're just starting now).
+		 */
+		vdev_scrub_stat_update(dp->dp_spa->spa_root_vdev,
+		    dp->dp_scrub_min_txg ? POOL_SCRUB_RESILVER :
+		    POOL_SCRUB_EVERYTHING, B_FALSE);
+	}
+
+	dp->dp_scrub_pausing = B_FALSE;
+	dp->dp_scrub_start_time = lbolt64;
+	dp->dp_scrub_isresilver = (dp->dp_scrub_min_txg != 0);
+	dp->dp_spa->spa_scrub_active = B_TRUE;
+
+	if (dp->dp_scrub_bookmark.zb_objset == 0) {
+		/* First do the MOS & ORIGIN */
+		scrub_visit_rootbp(dp, NULL, &dp->dp_meta_rootbp);
+		if (dp->dp_scrub_pausing)
+			goto out;
+
+		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 {
+			scrub_visitds(dp, dp->dp_origin_snap->ds_object, tx);
+		}
+		ASSERT(!dp->dp_scrub_pausing);
+	} else if (dp->dp_scrub_bookmark.zb_objset != -1ULL) {
+		/*
+		 * If we were paused, continue from here.  Note if the
+		 * ds we were paused on was deleted, the zb_objset will
+		 * be -1, so we will skip this and find a new objset
+		 * below.
+		 */
+		scrub_visitds(dp, dp->dp_scrub_bookmark.zb_objset, tx);
+		if (dp->dp_scrub_pausing)
+			goto out;
+	}
+
+	/*
+	 * 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(&dp->dp_scrub_bookmark, sizeof (zbookmark_t));
+
+	/* keep pulling things out of the zap-object-as-queue */
+	while (zap_cursor_init(&zc, dp->dp_meta_objset, dp->dp_scrub_queue_obj),
+	    zap_cursor_retrieve(&zc, &za) == 0) {
+		VERIFY(0 == zap_remove(dp->dp_meta_objset,
+		    dp->dp_scrub_queue_obj, za.za_name, tx));
+		scrub_visitds(dp, za.za_first_integer, tx);
+		if (dp->dp_scrub_pausing)
+			break;
+		zap_cursor_fini(&zc);
+	}
+	zap_cursor_fini(&zc);
+	if (dp->dp_scrub_pausing)
+		goto out;
+
+	/* done. */
+
+	dsl_pool_scrub_cancel_sync(dp, &complete, kcred, tx);
+	return;
+out:
+	VERIFY(0 == zap_update(dp->dp_meta_objset,
+	    DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_BOOKMARK, sizeof (uint64_t), 4,
+	    &dp->dp_scrub_bookmark, tx));
+	VERIFY(0 == zap_update(dp->dp_meta_objset,
+	    DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_SCRUB_ERRORS, sizeof (uint64_t), 1,
+	    &dp->dp_spa->spa_scrub_errors, tx));
+
+	/* XXX this is scrub-clean specific */
+	mutex_enter(&dp->dp_spa->spa_scrub_lock);
+	while (dp->dp_spa->spa_scrub_inflight > 0) {
+		cv_wait(&dp->dp_spa->spa_scrub_io_cv,
+		    &dp->dp_spa->spa_scrub_lock);
+	}
+	mutex_exit(&dp->dp_spa->spa_scrub_lock);
+}
+
+void
+dsl_pool_scrub_restart(dsl_pool_t *dp)
+{
+	mutex_enter(&dp->dp_scrub_cancel_lock);
+	dp->dp_scrub_restart = B_TRUE;
+	mutex_exit(&dp->dp_scrub_cancel_lock);
+}
+
+/*
+ * scrub consumers
+ */
+
+static void
+dsl_pool_scrub_clean_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_scrub_errors++;
+	mutex_exit(&spa->spa_scrub_lock);
+}
+
+static int
+dsl_pool_scrub_clean_cb(dsl_pool_t *dp,
+    const blkptr_t *bp, const zbookmark_t *zb)
+{
+	size_t size = BP_GET_LSIZE(bp);
+	int d;
+	spa_t *spa = dp->dp_spa;
+	boolean_t needs_io;
+	int zio_flags = ZIO_FLAG_SCRUB_THREAD | ZIO_FLAG_CANFAIL;
+	int zio_priority;
+
+	if (dp->dp_scrub_isresilver == 0) {
+		/* It's a scrub */
+		zio_flags |= ZIO_FLAG_SCRUB;
+		zio_priority = ZIO_PRIORITY_SCRUB;
+		needs_io = B_TRUE;
+	} else {
+		/* It's a resilver */
+		zio_flags |= ZIO_FLAG_RESILVER;
+		zio_priority = ZIO_PRIORITY_RESILVER;
+		needs_io = B_FALSE;
+	}
+
+	/* If it's an intent log block, failure is expected. */
+	if (zb->zb_level == -1 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)
+		zio_flags |= ZIO_FLAG_SPECULATIVE;
+
+	for (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.
+		 */
+		mutex_enter(&vd->vdev_stat_lock);
+		vd->vdev_stat.vs_scrub_examined +=
+		    DVA_GET_ASIZE(&bp->blk_dva[d]);
+		mutex_exit(&vd->vdev_stat_lock);
+
+		/* 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 we can do is look at the
+				 * pool-wide DTL.
+				 * XXX -- it would be better to change our
+				 * allocation policy to ensure that this can't
+				 * happen.
+				 */
+				vd = spa->spa_root_vdev;
+			}
+			needs_io = vdev_dtl_contains(&vd->vdev_dtl_map,
+			    bp->blk_birth, 1);
+		}
+	}
+
+	if (needs_io && !zfs_no_scrub_io) {
+		void *data = zio_data_buf_alloc(size);
+
+		mutex_enter(&spa->spa_scrub_lock);
+		while (spa->spa_scrub_inflight >= spa->spa_scrub_maxinflight)
+			cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
+		spa->spa_scrub_inflight++;
+		mutex_exit(&spa->spa_scrub_lock);
+
+		zio_nowait(zio_read(NULL, spa, bp, data, size,
+		    dsl_pool_scrub_clean_done, NULL, zio_priority,
+		    zio_flags, zb));
+	}
+
+	/* do not relocate this block */
+	return (0);
+}
+
+int
+dsl_pool_scrub_clean(dsl_pool_t *dp)
+{
+	/*
+	 * Purge all vdev caches.  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_config_enter(dp->dp_spa, SCL_ALL, FTAG, RW_WRITER);
+	dp->dp_spa->spa_scrub_reopen = B_TRUE;
+	vdev_reopen(dp->dp_spa->spa_root_vdev);
+	dp->dp_spa->spa_scrub_reopen = B_FALSE;
+	spa_config_exit(dp->dp_spa, SCL_ALL, FTAG);
+
+	return (dsl_pool_scrub_setup(dp, SCRUB_FUNC_CLEAN));
+}