Update core ZFS code from build 121 to build 141.

1 files changed, 781 insertions, 692 deletions

diff --git a/module/zfs/dsl_dataset.c b/module/zfs/dsl_dataset.c
index edc36e72b..ddd83576c 100644
--- a/module/zfs/dsl_dataset.c
+++ b/module/zfs/dsl_dataset.c
@@ -19,8 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 #include <sys/dmu_objset.h>
@@ -38,17 +37,28 @@
 #include <sys/zfs_ioctl.h>
 #include <sys/spa.h>
 #include <sys/zfs_znode.h>
-#include <sys/sunddi.h>
 #include <sys/zvol.h>
+#include <sys/dsl_scan.h>
+#include <sys/dsl_deadlist.h>
+
+/*
+ * Enable/disable prefetching of dedup-ed blocks which are going to be freed.
+ */
+int zfs_dedup_prefetch = 1;
 
 static char *dsl_reaper = "the grim reaper";
 
 static dsl_checkfunc_t dsl_dataset_destroy_begin_check;
 static dsl_syncfunc_t dsl_dataset_destroy_begin_sync;
-static dsl_checkfunc_t dsl_dataset_rollback_check;
-static dsl_syncfunc_t dsl_dataset_rollback_sync;
 static dsl_syncfunc_t dsl_dataset_set_reservation_sync;
 
+#define	SWITCH64(x, y) \
+	{ \
+		uint64_t __tmp = (x); \
+		(x) = (y); \
+		(y) = __tmp; \
+	}
+
 #define	DS_REF_MAX	(1ULL << 62)
 
 #define	DSL_DEADLIST_BLOCKSIZE	SPA_MAXBLOCKSIZE
@@ -77,14 +87,14 @@ parent_delta(dsl_dataset_t *ds, int64_t delta)
 }
 
 void
-dsl_dataset_block_born(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
+dsl_dataset_block_born(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx)
 {
-	int used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
+	int used = bp_get_dsize_sync(tx->tx_pool->dp_spa, bp);
 	int compressed = BP_GET_PSIZE(bp);
 	int uncompressed = BP_GET_UCSIZE(bp);
 	int64_t delta;
 
-	dprintf_bp(bp, "born, ds=%p\n", ds);
+	dprintf_bp(bp, "ds=%p", ds);
 
 	ASSERT(dmu_tx_is_syncing(tx));
 	/* It could have been compressed away to nothing */
@@ -104,6 +114,7 @@ dsl_dataset_block_born(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
 		return;
 	}
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
+
 	mutex_enter(&ds->ds_dir->dd_lock);
 	mutex_enter(&ds->ds_lock);
 	delta = parent_delta(ds, used);
@@ -120,29 +131,26 @@ dsl_dataset_block_born(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
 }
 
 int
-dsl_dataset_block_kill(dsl_dataset_t *ds, blkptr_t *bp, zio_t *pio,
-    dmu_tx_t *tx)
+dsl_dataset_block_kill(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx,
+    boolean_t async)
 {
-	int used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
-	int compressed = BP_GET_PSIZE(bp);
-	int uncompressed = BP_GET_UCSIZE(bp);
-
-	ASSERT(pio != NULL);
-	ASSERT(dmu_tx_is_syncing(tx));
-	/* No block pointer => nothing to free */
 	if (BP_IS_HOLE(bp))
 		return (0);
 
+	ASSERT(dmu_tx_is_syncing(tx));
+	ASSERT(bp->blk_birth <= tx->tx_txg);
+
+	int used = bp_get_dsize_sync(tx->tx_pool->dp_spa, bp);
+	int compressed = BP_GET_PSIZE(bp);
+	int uncompressed = BP_GET_UCSIZE(bp);
+
 	ASSERT(used > 0);
 	if (ds == NULL) {
-		int err;
 		/*
 		 * Account for the meta-objset space in its placeholder
 		 * dataset.
 		 */
-		err = dsl_free(pio, tx->tx_pool,
-		    tx->tx_txg, bp, NULL, NULL, ARC_NOWAIT);
-		ASSERT(err == 0);
+		dsl_free(tx->tx_pool, tx->tx_txg, bp);
 
 		dsl_dir_diduse_space(tx->tx_pool->dp_mos_dir, DD_USED_HEAD,
 		    -used, -compressed, -uncompressed, tx);
@@ -155,13 +163,10 @@ dsl_dataset_block_kill(dsl_dataset_t *ds, blkptr_t *bp, zio_t *pio,
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
 
 	if (bp->blk_birth > ds->ds_phys->ds_prev_snap_txg) {
-		int err;
 		int64_t delta;
 
-		dprintf_bp(bp, "freeing: %s", "");
-		err = dsl_free(pio, tx->tx_pool,
-		    tx->tx_txg, bp, NULL, NULL, ARC_NOWAIT);
-		ASSERT(err == 0);
+		dprintf_bp(bp, "freeing ds=%llu", ds->ds_object);
+		dsl_free(tx->tx_pool, tx->tx_txg, bp);
 
 		mutex_enter(&ds->ds_dir->dd_lock);
 		mutex_enter(&ds->ds_lock);
@@ -177,7 +182,18 @@ dsl_dataset_block_kill(dsl_dataset_t *ds, blkptr_t *bp, zio_t *pio,
 		mutex_exit(&ds->ds_dir->dd_lock);
 	} else {
 		dprintf_bp(bp, "putting on dead list: %s", "");
-		VERIFY(0 == bplist_enqueue(&ds->ds_deadlist, bp, tx));
+		if (async) {
+			/*
+			 * We are here as part of zio's write done callback,
+			 * which means we're a zio interrupt thread.  We can't
+			 * call dsl_deadlist_insert() now because it may block
+			 * waiting for I/O.  Instead, put bp on the deferred
+			 * queue and let dsl_pool_sync() finish the job.
+			 */
+			bplist_append(&ds->ds_pending_deadlist, bp);
+		} else {
+			dsl_deadlist_insert(&ds->ds_deadlist, bp, tx);
+		}
 		ASSERT3U(ds->ds_prev->ds_object, ==,
 		    ds->ds_phys->ds_prev_snap_obj);
 		ASSERT(ds->ds_prev->ds_phys->ds_num_children > 0);
@@ -190,7 +206,7 @@ dsl_dataset_block_kill(dsl_dataset_t *ds, blkptr_t *bp, zio_t *pio,
 			ds->ds_prev->ds_phys->ds_unique_bytes += used;
 			mutex_exit(&ds->ds_prev->ds_lock);
 		}
-		if (bp->blk_birth > ds->ds_origin_txg) {
+		if (bp->blk_birth > ds->ds_dir->dd_origin_txg) {
 			dsl_dir_transfer_space(ds->ds_dir, used,
 			    DD_USED_HEAD, DD_USED_SNAP, tx);
 		}
@@ -231,9 +247,16 @@ dsl_dataset_prev_snap_txg(dsl_dataset_t *ds)
 }
 
 boolean_t
-dsl_dataset_block_freeable(dsl_dataset_t *ds, uint64_t blk_birth)
+dsl_dataset_block_freeable(dsl_dataset_t *ds, const blkptr_t *bp,
+    uint64_t blk_birth)
 {
-	return (blk_birth > dsl_dataset_prev_snap_txg(ds));
+	if (blk_birth <= dsl_dataset_prev_snap_txg(ds))
+		return (B_FALSE);
+
+	if (zfs_dedup_prefetch && bp && BP_GET_DEDUP(bp))
+		ddt_prefetch(dsl_dataset_get_spa(ds), bp);
+
+	return (B_TRUE);
 }
 
 /* ARGSUSED */
@@ -244,19 +267,23 @@ dsl_dataset_evict(dmu_buf_t *db, void *dsv)
 
 	ASSERT(ds->ds_owner == NULL || DSL_DATASET_IS_DESTROYED(ds));
 
-	dprintf_ds(ds, "evicting %s\n", "");
-
 	unique_remove(ds->ds_fsid_guid);
 
-	if (ds->ds_user_ptr != NULL)
-		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
+	if (ds->ds_objset != NULL)
+		dmu_objset_evict(ds->ds_objset);
 
 	if (ds->ds_prev) {
 		dsl_dataset_drop_ref(ds->ds_prev, ds);
 		ds->ds_prev = NULL;
 	}
 
-	bplist_close(&ds->ds_deadlist);
+	bplist_destroy(&ds->ds_pending_deadlist);
+	if (db != NULL) {
+		dsl_deadlist_close(&ds->ds_deadlist);
+	} else {
+		ASSERT(ds->ds_deadlist.dl_dbuf == NULL);
+		ASSERT(!ds->ds_deadlist.dl_oldfmt);
+	}
 	if (ds->ds_dir)
 		dsl_dir_close(ds->ds_dir, ds);
 
@@ -265,7 +292,6 @@ dsl_dataset_evict(dmu_buf_t *db, void *dsv)
 	mutex_destroy(&ds->ds_lock);
 	mutex_destroy(&ds->ds_recvlock);
 	mutex_destroy(&ds->ds_opening_lock);
-	mutex_destroy(&ds->ds_deadlist.bpl_lock);
 	rw_destroy(&ds->ds_rwlock);
 	cv_destroy(&ds->ds_exclusive_cv);
 
@@ -325,6 +351,8 @@ dsl_dataset_snap_remove(dsl_dataset_t *ds, char *name, dmu_tx_t *tx)
 	matchtype_t mt;
 	int err;
 
+	dsl_dir_snap_cmtime_update(ds->ds_dir);
+
 	if (ds->ds_phys->ds_flags & DS_FLAG_CI_DATASET)
 		mt = MT_FIRST;
 	else
@@ -363,28 +391,25 @@ dsl_dataset_get_ref(dsl_pool_t *dp, uint64_t dsobj, void *tag,
 		mutex_init(&ds->ds_lock, NULL, MUTEX_DEFAULT, NULL);
 		mutex_init(&ds->ds_recvlock, NULL, MUTEX_DEFAULT, NULL);
 		mutex_init(&ds->ds_opening_lock, NULL, MUTEX_DEFAULT, NULL);
-		mutex_init(&ds->ds_deadlist.bpl_lock, NULL, MUTEX_DEFAULT,
-		    NULL);
 		rw_init(&ds->ds_rwlock, 0, 0, 0);
 		cv_init(&ds->ds_exclusive_cv, NULL, CV_DEFAULT, NULL);
 
-		err = bplist_open(&ds->ds_deadlist,
+		bplist_create(&ds->ds_pending_deadlist);
+		dsl_deadlist_open(&ds->ds_deadlist,
 		    mos, ds->ds_phys->ds_deadlist_obj);
+
 		if (err == 0) {
 			err = dsl_dir_open_obj(dp,
 			    ds->ds_phys->ds_dir_obj, NULL, ds, &ds->ds_dir);
 		}
 		if (err) {
-			/*
-			 * we don't really need to close the blist if we
-			 * just opened it.
-			 */
 			mutex_destroy(&ds->ds_lock);
 			mutex_destroy(&ds->ds_recvlock);
 			mutex_destroy(&ds->ds_opening_lock);
-			mutex_destroy(&ds->ds_deadlist.bpl_lock);
 			rw_destroy(&ds->ds_rwlock);
 			cv_destroy(&ds->ds_exclusive_cv);
+			bplist_destroy(&ds->ds_pending_deadlist);
+			dsl_deadlist_close(&ds->ds_deadlist);
 			kmem_free(ds, sizeof (dsl_dataset_t));
 			dmu_buf_rele(dbuf, tag);
 			return (err);
@@ -397,19 +422,6 @@ dsl_dataset_get_ref(dsl_pool_t *dp, uint64_t dsobj, void *tag,
 				    ds->ds_phys->ds_prev_snap_obj,
 				    ds, &ds->ds_prev);
 			}
-
-			if (err == 0 && dsl_dir_is_clone(ds->ds_dir)) {
-				dsl_dataset_t *origin;
-
-				err = dsl_dataset_hold_obj(dp,
-				    ds->ds_dir->dd_phys->dd_origin_obj,
-				    FTAG, &origin);
-				if (err == 0) {
-					ds->ds_origin_txg =
-					    origin->ds_phys->ds_creation_txg;
-					dsl_dataset_rele(origin, FTAG);
-				}
-			}
 		} else {
 			if (zfs_flags & ZFS_DEBUG_SNAPNAMES)
 				err = dsl_dataset_get_snapname(ds);
@@ -454,14 +466,14 @@ dsl_dataset_get_ref(dsl_pool_t *dp, uint64_t dsobj, void *tag,
 			    dsl_dataset_evict);
 		}
 		if (err || winner) {
-			bplist_close(&ds->ds_deadlist);
+			bplist_destroy(&ds->ds_pending_deadlist);
+			dsl_deadlist_close(&ds->ds_deadlist);
 			if (ds->ds_prev)
 				dsl_dataset_drop_ref(ds->ds_prev, ds);
 			dsl_dir_close(ds->ds_dir, ds);
 			mutex_destroy(&ds->ds_lock);
 			mutex_destroy(&ds->ds_recvlock);
 			mutex_destroy(&ds->ds_opening_lock);
-			mutex_destroy(&ds->ds_deadlist.bpl_lock);
 			rw_destroy(&ds->ds_rwlock);
 			cv_destroy(&ds->ds_exclusive_cv);
 			kmem_free(ds, sizeof (dsl_dataset_t));
@@ -531,7 +543,15 @@ dsl_dataset_hold_ref(dsl_dataset_t *ds, void *tag)
 			rw_enter(&dp->dp_config_rwlock, RW_READER);
 			return (ENOENT);
 		}
+		/*
+		 * The dp_config_rwlock lives above the ds_lock. And
+		 * we need to check DSL_DATASET_IS_DESTROYED() while
+		 * holding the ds_lock, so we have to drop and reacquire
+		 * the ds_lock here.
+		 */
+		mutex_exit(&ds->ds_lock);
 		rw_enter(&dp->dp_config_rwlock, RW_READER);
+		mutex_enter(&ds->ds_lock);
 	}
 	mutex_exit(&ds->ds_lock);
 	return (0);
@@ -549,17 +569,14 @@ dsl_dataset_hold_obj(dsl_pool_t *dp, uint64_t dsobj, void *tag,
 }
 
 int
-dsl_dataset_own_obj(dsl_pool_t *dp, uint64_t dsobj, int flags, void *owner,
-    dsl_dataset_t **dsp)
+dsl_dataset_own_obj(dsl_pool_t *dp, uint64_t dsobj, boolean_t inconsistentok,
+    void *tag, dsl_dataset_t **dsp)
 {
-	int err = dsl_dataset_hold_obj(dp, dsobj, owner, dsp);
-
-	ASSERT(DS_MODE_TYPE(flags) != DS_MODE_USER);
-
+	int err = dsl_dataset_hold_obj(dp, dsobj, tag, dsp);
 	if (err)
 		return (err);
-	if (!dsl_dataset_tryown(*dsp, DS_MODE_IS_INCONSISTENT(flags), owner)) {
-		dsl_dataset_rele(*dsp, owner);
+	if (!dsl_dataset_tryown(*dsp, inconsistentok, tag)) {
+		dsl_dataset_rele(*dsp, tag);
 		*dsp = NULL;
 		return (EBUSY);
 	}
@@ -626,18 +643,14 @@ out:
 }
 
 int
-dsl_dataset_own(const char *name, int flags, void *owner, dsl_dataset_t **dsp)
+dsl_dataset_own(const char *name, boolean_t inconsistentok,
+    void *tag, dsl_dataset_t **dsp)
 {
-	int err = dsl_dataset_hold(name, owner, dsp);
+	int err = dsl_dataset_hold(name, tag, dsp);
 	if (err)
 		return (err);
-	if ((*dsp)->ds_phys->ds_num_children > 0 &&
-	    !DS_MODE_IS_READONLY(flags)) {
-		dsl_dataset_rele(*dsp, owner);
-		return (EROFS);
-	}
-	if (!dsl_dataset_tryown(*dsp, DS_MODE_IS_INCONSISTENT(flags), owner)) {
-		dsl_dataset_rele(*dsp, owner);
+	if (!dsl_dataset_tryown(*dsp, inconsistentok, tag)) {
+		dsl_dataset_rele(*dsp, tag);
 		return (EBUSY);
 	}
 	return (0);
@@ -709,9 +722,9 @@ dsl_dataset_rele(dsl_dataset_t *ds, void *tag)
 }
 
 void
-dsl_dataset_disown(dsl_dataset_t *ds, void *owner)
+dsl_dataset_disown(dsl_dataset_t *ds, void *tag)
 {
-	ASSERT((ds->ds_owner == owner && ds->ds_dbuf) ||
+	ASSERT((ds->ds_owner == tag && ds->ds_dbuf) ||
 	    (DSL_DATASET_IS_DESTROYED(ds) && ds->ds_dbuf == NULL));
 
 	mutex_enter(&ds->ds_lock);
@@ -722,20 +735,20 @@ dsl_dataset_disown(dsl_dataset_t *ds, void *owner)
 	}
 	mutex_exit(&ds->ds_lock);
 	if (ds->ds_dbuf)
-		dsl_dataset_drop_ref(ds, owner);
+		dsl_dataset_drop_ref(ds, tag);
 	else
-		dsl_dataset_evict(ds->ds_dbuf, ds);
+		dsl_dataset_evict(NULL, ds);
 }
 
 boolean_t
-dsl_dataset_tryown(dsl_dataset_t *ds, boolean_t inconsistentok, void *owner)
+dsl_dataset_tryown(dsl_dataset_t *ds, boolean_t inconsistentok, void *tag)
 {
 	boolean_t gotit = FALSE;
 
 	mutex_enter(&ds->ds_lock);
 	if (ds->ds_owner == NULL &&
 	    (!DS_IS_INCONSISTENT(ds) || inconsistentok)) {
-		ds->ds_owner = owner;
+		ds->ds_owner = tag;
 		if (!dsl_pool_sync_context(ds->ds_dir->dd_pool))
 			rw_exit(&ds->ds_rwlock);
 		gotit = TRUE;
@@ -786,10 +799,12 @@ dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
 	    DMU_OT_NONE, 0, tx);
 	dsphys->ds_creation_time = gethrestime_sec();
 	dsphys->ds_creation_txg = tx->tx_txg == TXG_INITIAL ? 1 : tx->tx_txg;
-	dsphys->ds_deadlist_obj =
-	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
 
-	if (origin) {
+	if (origin == NULL) {
+		dsphys->ds_deadlist_obj = dsl_deadlist_alloc(mos, tx);
+	} else {
+		dsl_dataset_t *ohds;
+
 		dsphys->ds_prev_snap_obj = origin->ds_object;
 		dsphys->ds_prev_snap_txg =
 		    origin->ds_phys->ds_creation_txg;
@@ -805,6 +820,12 @@ dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
 		dmu_buf_will_dirty(origin->ds_dbuf, tx);
 		origin->ds_phys->ds_num_children++;
 
+		VERIFY3U(0, ==, dsl_dataset_hold_obj(dp,
+		    origin->ds_dir->dd_phys->dd_head_dataset_obj, FTAG, &ohds));
+		dsphys->ds_deadlist_obj = dsl_deadlist_clone(&ohds->ds_deadlist,
+		    dsphys->ds_prev_snap_txg, dsphys->ds_prev_snap_obj, tx);
+		dsl_dataset_rele(ohds, FTAG);
+
 		if (spa_version(dp->dp_spa) >= SPA_VERSION_NEXT_CLONES) {
 			if (origin->ds_phys->ds_next_clones_obj == 0) {
 				origin->ds_phys->ds_next_clones_obj =
@@ -818,6 +839,16 @@ dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
 
 		dmu_buf_will_dirty(dd->dd_dbuf, tx);
 		dd->dd_phys->dd_origin_obj = origin->ds_object;
+		if (spa_version(dp->dp_spa) >= SPA_VERSION_DIR_CLONES) {
+			if (origin->ds_dir->dd_phys->dd_clones == 0) {
+				dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
+				origin->ds_dir->dd_phys->dd_clones =
+				    zap_create(mos,
+				    DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
+			}
+			VERIFY3U(0, ==, zap_add_int(mos,
+			    origin->ds_dir->dd_phys->dd_clones, dsobj, tx));
+		}
 	}
 
 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
@@ -861,29 +892,20 @@ struct destroyarg {
 };
 
 static int
-dsl_snapshot_destroy_one(char *name, void *arg)
+dsl_snapshot_destroy_one(const char *name, void *arg)
 {
 	struct destroyarg *da = arg;
 	dsl_dataset_t *ds;
 	int err;
 	char *dsname;
-	size_t buflen;
-
-	/* alloc a buffer to hold name@snapname, plus the terminating NULL */
-	buflen = strlen(name) + strlen(da->snapname) + 2;
-	dsname = kmem_alloc(buflen, KM_SLEEP);
-	(void) snprintf(dsname, buflen, "%s@%s", name, da->snapname);
-	err = dsl_dataset_own(dsname, DS_MODE_READONLY | DS_MODE_INCONSISTENT,
-	    da->dstg, &ds);
-	kmem_free(dsname, buflen);
+
+	dsname = kmem_asprintf("%s@%s", name, da->snapname);
+	err = dsl_dataset_own(dsname, B_TRUE, da->dstg, &ds);
+	strfree(dsname);
 	if (err == 0) {
 		struct dsl_ds_destroyarg *dsda;
 
 		dsl_dataset_make_exclusive(ds, da->dstg);
-		if (ds->ds_user_ptr) {
-			ds->ds_user_evict_func(ds, ds->ds_user_ptr);
-			ds->ds_user_ptr = NULL;
-		}
 		dsda = kmem_zalloc(sizeof (struct dsl_ds_destroyarg), KM_SLEEP);
 		dsda->ds = ds;
 		dsda->defer = da->defer;
@@ -959,25 +981,6 @@ dsl_dataset_might_destroy_origin(dsl_dataset_t *ds)
 	return (might_destroy);
 }
 
-#ifdef _KERNEL
-static int
-dsl_dataset_zvol_cleanup(dsl_dataset_t *ds, const char *name)
-{
-	int error;
-	objset_t *os;
-
-	error = dmu_objset_open_ds(ds, DMU_OST_ANY, &os);
-	if (error)
-		return (error);
-
-	if (dmu_objset_type(os) == DMU_OST_ZVOL)
-		error = zvol_remove_minor(name);
-	dmu_objset_close(os);
-
-	return (error);
-}
-#endif
-
 /*
  * If we're removing a clone, and these three conditions are true:
  *	1) the clone's origin has no other children
@@ -1005,15 +1008,8 @@ dsl_dataset_origin_rm_prep(struct dsl_ds_destroyarg *dsda, void *tag)
 			kmem_free(name, namelen);
 			return (error);
 		}
-		error = dsl_dataset_zvol_cleanup(origin, name);
-		if (error) {
-			kmem_free(name, namelen);
-			return (error);
-		}
 #endif
-		error = dsl_dataset_own(name,
-		    DS_MODE_READONLY | DS_MODE_INCONSISTENT,
-		    tag, &origin);
+		error = dsl_dataset_own(name, B_TRUE, tag, &origin);
 		kmem_free(name, namelen);
 		if (error)
 			return (error);
@@ -1036,7 +1032,8 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 	objset_t *os;
 	dsl_dir_t *dd;
 	uint64_t obj;
-	struct dsl_ds_destroyarg dsda = {0};
+	struct dsl_ds_destroyarg dsda = { 0 };
+	dsl_dataset_t dummy_ds = { 0 };
 
 	dsda.ds = ds;
 
@@ -1044,20 +1041,20 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 		/* Destroying a snapshot is simpler */
 		dsl_dataset_make_exclusive(ds, tag);
 
-		if (ds->ds_user_ptr) {
-			ds->ds_user_evict_func(ds, ds->ds_user_ptr);
-			ds->ds_user_ptr = NULL;
-		}
-		/* NOTE: defer is always B_FALSE for non-snapshots */
 		dsda.defer = defer;
 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
 		    dsl_dataset_destroy_check, dsl_dataset_destroy_sync,
 		    &dsda, tag, 0);
 		ASSERT3P(dsda.rm_origin, ==, NULL);
 		goto out;
+	} else if (defer) {
+		err = EINVAL;
+		goto out;
 	}
 
 	dd = ds->ds_dir;
+	dummy_ds.ds_dir = dd;
+	dummy_ds.ds_object = ds->ds_object;
 
 	/*
 	 * Check for errors and mark this ds as inconsistent, in
@@ -1068,7 +1065,7 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 	if (err)
 		goto out;
 
-	err = dmu_objset_open_ds(ds, DMU_OST_ANY, &os);
+	err = dmu_objset_from_ds(ds, &os);
 	if (err)
 		goto out;
 
@@ -1097,7 +1094,7 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 	 * context, the user space accounting should be zero.
 	 */
 	if (ds->ds_phys->ds_bp.blk_fill == 0 &&
-	    dmu_objset_userused_enabled(os->os)) {
+	    dmu_objset_userused_enabled(os)) {
 		uint64_t count;
 
 		ASSERT(zap_count(os, DMU_USERUSED_OBJECT, &count) != 0 ||
@@ -1106,7 +1103,6 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 		    count == 0);
 	}
 
-	dmu_objset_close(os);
 	if (err != ESRCH)
 		goto out;
 
@@ -1117,24 +1113,10 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 	if (err)
 		goto out;
 
-	if (ds->ds_user_ptr) {
-		/*
-		 * We need to sync out all in-flight IO before we try
-		 * to evict (the dataset evict func is trying to clear
-		 * the cached entries for this dataset in the ARC).
-		 */
-		txg_wait_synced(dd->dd_pool, 0);
-	}
-
 	/*
 	 * Blow away the dsl_dir + head dataset.
 	 */
 	dsl_dataset_make_exclusive(ds, tag);
-	if (ds->ds_user_ptr) {
-		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
-		ds->ds_user_ptr = NULL;
-	}
-
 	/*
 	 * If we're removing a clone, we might also need to remove its
 	 * origin.
@@ -1153,7 +1135,7 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 		dsl_sync_task_create(dstg, dsl_dataset_destroy_check,
 		    dsl_dataset_destroy_sync, &dsda, tag, 0);
 		dsl_sync_task_create(dstg, dsl_dir_destroy_check,
-		    dsl_dir_destroy_sync, dd, FTAG, 0);
+		    dsl_dir_destroy_sync, &dummy_ds, FTAG, 0);
 		err = dsl_sync_task_group_wait(dstg);
 		dsl_sync_task_group_destroy(dstg);
 
@@ -1181,47 +1163,6 @@ out:
 	return (err);
 }
 
-int
-dsl_dataset_rollback(dsl_dataset_t *ds, dmu_objset_type_t ost)
-{
-	int err;
-
-	ASSERT(ds->ds_owner);
-
-	dsl_dataset_make_exclusive(ds, ds->ds_owner);
-	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
-	    dsl_dataset_rollback_check, dsl_dataset_rollback_sync,
-	    ds, &ost, 0);
-	/* drop exclusive access */
-	mutex_enter(&ds->ds_lock);
-	rw_exit(&ds->ds_rwlock);
-	cv_broadcast(&ds->ds_exclusive_cv);
-	mutex_exit(&ds->ds_lock);
-	return (err);
-}
-
-void *
-dsl_dataset_set_user_ptr(dsl_dataset_t *ds,
-    void *p, dsl_dataset_evict_func_t func)
-{
-	void *old;
-
-	mutex_enter(&ds->ds_lock);
-	old = ds->ds_user_ptr;
-	if (old == NULL) {
-		ds->ds_user_ptr = p;
-		ds->ds_user_evict_func = func;
-	}
-	mutex_exit(&ds->ds_lock);
-	return (old);
-}
-
-void *
-dsl_dataset_get_user_ptr(dsl_dataset_t *ds)
-{
-	return (ds->ds_user_ptr);
-}
-
 blkptr_t *
 dsl_dataset_get_blkptr(dsl_dataset_t *ds)
 {
@@ -1255,7 +1196,7 @@ dsl_dataset_dirty(dsl_dataset_t *ds, dmu_tx_t *tx)
 	if (ds == NULL) /* this is the meta-objset */
 		return;
 
-	ASSERT(ds->ds_user_ptr != NULL);
+	ASSERT(ds->ds_objset != NULL);
 
 	if (ds->ds_phys->ds_next_snap_obj != 0)
 		panic("dirtying snapshot!");
@@ -1282,62 +1223,51 @@ dsl_dataset_recalc_head_uniq(dsl_dataset_t *ds)
 	uint64_t mrs_used;
 	uint64_t dlused, dlcomp, dluncomp;
 
-	ASSERT(ds->ds_object == ds->ds_dir->dd_phys->dd_head_dataset_obj);
+	ASSERT(!dsl_dataset_is_snapshot(ds));
 
 	if (ds->ds_phys->ds_prev_snap_obj != 0)
 		mrs_used = ds->ds_prev->ds_phys->ds_used_bytes;
 	else
 		mrs_used = 0;
 
-	VERIFY(0 == bplist_space(&ds->ds_deadlist, &dlused, &dlcomp,
-	    &dluncomp));
+	dsl_deadlist_space(&ds->ds_deadlist, &dlused, &dlcomp, &dluncomp);
 
 	ASSERT3U(dlused, <=, mrs_used);
 	ds->ds_phys->ds_unique_bytes =
 	    ds->ds_phys->ds_used_bytes - (mrs_used - dlused);
 
-	if (!DS_UNIQUE_IS_ACCURATE(ds) &&
-	    spa_version(ds->ds_dir->dd_pool->dp_spa) >=
+	if (spa_version(ds->ds_dir->dd_pool->dp_spa) >=
 	    SPA_VERSION_UNIQUE_ACCURATE)
 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
 }
 
-static uint64_t
-dsl_dataset_unique(dsl_dataset_t *ds)
-{
-	if (!DS_UNIQUE_IS_ACCURATE(ds) && !dsl_dataset_is_snapshot(ds))
-		dsl_dataset_recalc_head_uniq(ds);
-
-	return (ds->ds_phys->ds_unique_bytes);
-}
-
 struct killarg {
 	dsl_dataset_t *ds;
-	zio_t *zio;
 	dmu_tx_t *tx;
 };
 
 /* ARGSUSED */
 static int
-kill_blkptr(spa_t *spa, blkptr_t *bp, const zbookmark_t *zb,
-    const dnode_phys_t *dnp, void *arg)
+kill_blkptr(spa_t *spa, zilog_t *zilog, const blkptr_t *bp, arc_buf_t *pbuf,
+    const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
 {
 	struct killarg *ka = arg;
+	dmu_tx_t *tx = ka->tx;
 
 	if (bp == NULL)
 		return (0);
 
-	if ((zb->zb_level == -1ULL && zb->zb_blkid != 0) ||
-	    (zb->zb_object != 0 && dnp == NULL)) {
+	if (zb->zb_level == ZB_ZIL_LEVEL) {
+		ASSERT(zilog != NULL);
 		/*
 		 * It's a block in the intent log.  It has no
 		 * accounting, so just free it.
 		 */
-		VERIFY3U(0, ==, dsl_free(ka->zio, ka->tx->tx_pool,
-		    ka->tx->tx_txg, bp, NULL, NULL, ARC_NOWAIT));
+		dsl_free(ka->tx->tx_pool, ka->tx->tx_txg, bp);
 	} else {
+		ASSERT(zilog == NULL);
 		ASSERT3U(bp->blk_birth, >, ka->ds->ds_phys->ds_prev_snap_txg);
-		(void) dsl_dataset_block_kill(ka->ds, bp, ka->zio, ka->tx);
+		(void) dsl_dataset_block_kill(ka->ds, bp, tx, B_FALSE);
 	}
 
 	return (0);
@@ -1345,145 +1275,6 @@ kill_blkptr(spa_t *spa, blkptr_t *bp, const zbookmark_t *zb,
 
 /* ARGSUSED */
 static int
-dsl_dataset_rollback_check(void *arg1, void *arg2, dmu_tx_t *tx)
-{
-	dsl_dataset_t *ds = arg1;
-	dmu_objset_type_t *ost = arg2;
-
-	/*
-	 * We can only roll back to emptyness if it is a ZPL objset.
-	 */
-	if (*ost != DMU_OST_ZFS &&
-	    ds->ds_phys->ds_prev_snap_txg < TXG_INITIAL)
-		return (EINVAL);
-
-	/*
-	 * This must not be a snapshot.
-	 */
-	if (ds->ds_phys->ds_next_snap_obj != 0)
-		return (EINVAL);
-
-	/*
-	 * If we made changes this txg, traverse_dataset won't find
-	 * them.  Try again.
-	 */
-	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
-		return (EAGAIN);
-
-	return (0);
-}
-
-/* ARGSUSED */
-static void
-dsl_dataset_rollback_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
-{
-	dsl_dataset_t *ds = arg1;
-	dmu_objset_type_t *ost = arg2;
-	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
-
-	dmu_buf_will_dirty(ds->ds_dbuf, tx);
-
-	if (ds->ds_user_ptr != NULL) {
-		/*
-		 * We need to make sure that the objset_impl_t is reopened after
-		 * we do the rollback, otherwise it will have the wrong
-		 * objset_phys_t.  Normally this would happen when this
-		 * dataset-open is closed, thus causing the
-		 * dataset to be immediately evicted.  But when doing "zfs recv
-		 * -F", we reopen the objset before that, so that there is no
-		 * window where the dataset is closed and inconsistent.
-		 */
-		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
-		ds->ds_user_ptr = NULL;
-	}
-
-	/* Transfer space that was freed since last snap back to the head. */
-	{
-		uint64_t used;
-
-		VERIFY(0 == bplist_space_birthrange(&ds->ds_deadlist,
-		    ds->ds_origin_txg, UINT64_MAX, &used));
-		dsl_dir_transfer_space(ds->ds_dir, used,
-		    DD_USED_SNAP, DD_USED_HEAD, tx);
-	}
-
-	/* Zero out the deadlist. */
-	bplist_close(&ds->ds_deadlist);
-	bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
-	ds->ds_phys->ds_deadlist_obj =
-	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
-	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
-	    ds->ds_phys->ds_deadlist_obj));
-
-	{
-		/*
-		 * Free blkptrs that we gave birth to - this covers
-		 * claimed but not played log blocks too.
-		 */
-		zio_t *zio;
-		struct killarg ka;
-
-		zio = zio_root(tx->tx_pool->dp_spa, NULL, NULL,
-		    ZIO_FLAG_MUSTSUCCEED);
-		ka.ds = ds;
-		ka.zio = zio;
-		ka.tx = tx;
-		(void) traverse_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
-		    TRAVERSE_POST, kill_blkptr, &ka);
-		(void) zio_wait(zio);
-	}
-
-	ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) || ds->ds_phys->ds_unique_bytes == 0);
-
-	if (ds->ds_prev && ds->ds_prev != ds->ds_dir->dd_pool->dp_origin_snap) {
-		/* Change our contents to that of the prev snapshot */
-
-		ASSERT3U(ds->ds_prev->ds_object, ==,
-		    ds->ds_phys->ds_prev_snap_obj);
-		ASSERT3U(ds->ds_phys->ds_used_bytes, <=,
-		    ds->ds_prev->ds_phys->ds_used_bytes);
-
-		ds->ds_phys->ds_bp = ds->ds_prev->ds_phys->ds_bp;
-		ds->ds_phys->ds_used_bytes =
-		    ds->ds_prev->ds_phys->ds_used_bytes;
-		ds->ds_phys->ds_compressed_bytes =
-		    ds->ds_prev->ds_phys->ds_compressed_bytes;
-		ds->ds_phys->ds_uncompressed_bytes =
-		    ds->ds_prev->ds_phys->ds_uncompressed_bytes;
-		ds->ds_phys->ds_flags = ds->ds_prev->ds_phys->ds_flags;
-
-		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
-			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
-			ds->ds_prev->ds_phys->ds_unique_bytes = 0;
-		}
-	} else {
-		objset_impl_t *osi;
-
-		ASSERT(*ost != DMU_OST_ZVOL);
-		ASSERT3U(ds->ds_phys->ds_used_bytes, ==, 0);
-		ASSERT3U(ds->ds_phys->ds_compressed_bytes, ==, 0);
-		ASSERT3U(ds->ds_phys->ds_uncompressed_bytes, ==, 0);
-
-		bzero(&ds->ds_phys->ds_bp, sizeof (blkptr_t));
-		ds->ds_phys->ds_flags = 0;
-		ds->ds_phys->ds_unique_bytes = 0;
-		if (spa_version(ds->ds_dir->dd_pool->dp_spa) >=
-		    SPA_VERSION_UNIQUE_ACCURATE)
-			ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
-
-		osi = dmu_objset_create_impl(ds->ds_dir->dd_pool->dp_spa, ds,
-		    &ds->ds_phys->ds_bp, *ost, tx);
-#ifdef _KERNEL
-		zfs_create_fs(&osi->os, kcred, NULL, tx);
-#endif
-	}
-
-	spa_history_internal_log(LOG_DS_ROLLBACK, ds->ds_dir->dd_pool->dp_spa,
-	    tx, cr, "dataset = %llu", ds->ds_object);
-}
-
-/* ARGSUSED */
-static int
 dsl_dataset_destroy_begin_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
@@ -1498,7 +1289,7 @@ dsl_dataset_destroy_begin_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	 */
 	if (ds->ds_prev != NULL &&
 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
-		return (EINVAL);
+		return (EBUSY);
 
 	/*
 	 * This is really a dsl_dir thing, but check it here so that
@@ -1516,7 +1307,7 @@ dsl_dataset_destroy_begin_check(void *arg1, void *arg2, dmu_tx_t *tx)
 
 /* ARGSUSED */
 static void
-dsl_dataset_destroy_begin_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_destroy_begin_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
@@ -1525,8 +1316,8 @@ dsl_dataset_destroy_begin_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
 	ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
 
-	spa_history_internal_log(LOG_DS_DESTROY_BEGIN, dp->dp_spa, tx,
-	    cr, "dataset = %llu", ds->ds_object);
+	spa_history_log_internal(LOG_DS_DESTROY_BEGIN, dp->dp_spa, tx,
+	    "dataset = %llu", ds->ds_object);
 }
 
 static int
@@ -1594,7 +1385,7 @@ dsl_dataset_destroy_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	 */
 	if (ds->ds_prev != NULL &&
 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
-		return (EINVAL);
+		return (EBUSY);
 
 	/*
 	 * If we made changes this txg, traverse_dsl_dataset won't find
@@ -1672,12 +1463,135 @@ dsl_dataset_drain_refs(dsl_dataset_t *ds, void *tag)
 	cv_destroy(&arg.cv);
 }
 
+static void
+remove_from_next_clones(dsl_dataset_t *ds, uint64_t obj, dmu_tx_t *tx)
+{
+	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
+	uint64_t count;
+	int err;
+
+	ASSERT(ds->ds_phys->ds_num_children >= 2);
+	err = zap_remove_int(mos, ds->ds_phys->ds_next_clones_obj, obj, tx);
+	/*
+	 * The err should not be ENOENT, but 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.
+	 * If we knew that the pool was created after
+	 * SPA_VERSION_NEXT_CLONES, we could assert that it isn't
+	 * ENOENT.  However, at least we can check that we don't have
+	 * too many entries in the next_clones_obj even after failing to
+	 * remove this one.
+	 */
+	if (err != ENOENT) {
+		VERIFY3U(err, ==, 0);
+	}
+	ASSERT3U(0, ==, zap_count(mos, ds->ds_phys->ds_next_clones_obj,
+	    &count));
+	ASSERT3U(count, <=, ds->ds_phys->ds_num_children - 2);
+}
+
+static void
+dsl_dataset_remove_clones_key(dsl_dataset_t *ds, uint64_t mintxg, dmu_tx_t *tx)
+{
+	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
+	zap_cursor_t zc;
+	zap_attribute_t za;
+
+	/*
+	 * If it is the old version, dd_clones doesn't exist so we can't
+	 * find the clones, but deadlist_remove_key() is a no-op so it
+	 * doesn't matter.
+	 */
+	if (ds->ds_dir->dd_phys->dd_clones == 0)
+		return;
+
+	for (zap_cursor_init(&zc, mos, ds->ds_dir->dd_phys->dd_clones);
+	    zap_cursor_retrieve(&zc, &za) == 0;
+	    zap_cursor_advance(&zc)) {
+		dsl_dataset_t *clone;
+
+		VERIFY3U(0, ==, dsl_dataset_hold_obj(ds->ds_dir->dd_pool,
+		    za.za_first_integer, FTAG, &clone));
+		if (clone->ds_dir->dd_origin_txg > mintxg) {
+			dsl_deadlist_remove_key(&clone->ds_deadlist,
+			    mintxg, tx);
+			dsl_dataset_remove_clones_key(clone, mintxg, tx);
+		}
+		dsl_dataset_rele(clone, FTAG);
+	}
+	zap_cursor_fini(&zc);
+}
+
+struct process_old_arg {
+	dsl_dataset_t *ds;
+	dsl_dataset_t *ds_prev;
+	boolean_t after_branch_point;
+	zio_t *pio;
+	uint64_t used, comp, uncomp;
+};
+
+static int
+process_old_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
+{
+	struct process_old_arg *poa = arg;
+	dsl_pool_t *dp = poa->ds->ds_dir->dd_pool;
+
+	if (bp->blk_birth <= poa->ds->ds_phys->ds_prev_snap_txg) {
+		dsl_deadlist_insert(&poa->ds->ds_deadlist, bp, tx);
+		if (poa->ds_prev && !poa->after_branch_point &&
+		    bp->blk_birth >
+		    poa->ds_prev->ds_phys->ds_prev_snap_txg) {
+			poa->ds_prev->ds_phys->ds_unique_bytes +=
+			    bp_get_dsize_sync(dp->dp_spa, bp);
+		}
+	} else {
+		poa->used += bp_get_dsize_sync(dp->dp_spa, bp);
+		poa->comp += BP_GET_PSIZE(bp);
+		poa->uncomp += BP_GET_UCSIZE(bp);
+		dsl_free_sync(poa->pio, dp, tx->tx_txg, bp);
+	}
+	return (0);
+}
+
+static void
+process_old_deadlist(dsl_dataset_t *ds, dsl_dataset_t *ds_prev,
+    dsl_dataset_t *ds_next, boolean_t after_branch_point, dmu_tx_t *tx)
+{
+	struct process_old_arg poa = { 0 };
+	dsl_pool_t *dp = ds->ds_dir->dd_pool;
+	objset_t *mos = dp->dp_meta_objset;
+
+	ASSERT(ds->ds_deadlist.dl_oldfmt);
+	ASSERT(ds_next->ds_deadlist.dl_oldfmt);
+
+	poa.ds = ds;
+	poa.ds_prev = ds_prev;
+	poa.after_branch_point = after_branch_point;
+	poa.pio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
+	VERIFY3U(0, ==, bpobj_iterate(&ds_next->ds_deadlist.dl_bpobj,
+	    process_old_cb, &poa, tx));
+	VERIFY3U(zio_wait(poa.pio), ==, 0);
+	ASSERT3U(poa.used, ==, ds->ds_phys->ds_unique_bytes);
+
+	/* change snapused */
+	dsl_dir_diduse_space(ds->ds_dir, DD_USED_SNAP,
+	    -poa.used, -poa.comp, -poa.uncomp, tx);
+
+	/* swap next's deadlist to our deadlist */
+	dsl_deadlist_close(&ds->ds_deadlist);
+	dsl_deadlist_close(&ds_next->ds_deadlist);
+	SWITCH64(ds_next->ds_phys->ds_deadlist_obj,
+	    ds->ds_phys->ds_deadlist_obj);
+	dsl_deadlist_open(&ds->ds_deadlist, mos, ds->ds_phys->ds_deadlist_obj);
+	dsl_deadlist_open(&ds_next->ds_deadlist, mos,
+	    ds_next->ds_phys->ds_deadlist_obj);
+}
+
 void
-dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 {
 	struct dsl_ds_destroyarg *dsda = arg1;
 	dsl_dataset_t *ds = dsda->ds;
-	zio_t *zio;
 	int err;
 	int after_branch_point = FALSE;
 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
@@ -1706,16 +1620,28 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 	cv_broadcast(&ds->ds_exclusive_cv);
 	mutex_exit(&ds->ds_lock);
 
+	if (ds->ds_objset) {
+		dmu_objset_evict(ds->ds_objset);
+		ds->ds_objset = NULL;
+	}
+
 	/* Remove our reservation */
 	if (ds->ds_reserved != 0) {
-		uint64_t val = 0;
-		dsl_dataset_set_reservation_sync(ds, &val, cr, tx);
+		dsl_prop_setarg_t psa;
+		uint64_t value = 0;
+
+		dsl_prop_setarg_init_uint64(&psa, "refreservation",
+		    (ZPROP_SRC_NONE | ZPROP_SRC_LOCAL | ZPROP_SRC_RECEIVED),
+		    &value);
+		psa.psa_effective_value = 0;	/* predict default value */
+
+		dsl_dataset_set_reservation_sync(ds, &psa, tx);
 		ASSERT3U(ds->ds_reserved, ==, 0);
 	}
 
 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
 
-	dsl_pool_ds_destroyed(ds, tx);
+	dsl_scan_ds_destroyed(ds, tx);
 
 	obj = ds->ds_object;
 
@@ -1732,8 +1658,7 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		dmu_buf_will_dirty(ds_prev->ds_dbuf, tx);
 		if (after_branch_point &&
 		    ds_prev->ds_phys->ds_next_clones_obj != 0) {
-			VERIFY3U(0, ==, zap_remove_int(mos,
-			    ds_prev->ds_phys->ds_next_clones_obj, obj, tx));
+			remove_from_next_clones(ds_prev, obj, tx);
 			if (ds->ds_phys->ds_next_snap_obj != 0) {
 				VERIFY(0 == zap_add_int(mos,
 				    ds_prev->ds_phys->ds_next_clones_obj,
@@ -1765,20 +1690,16 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		}
 	}
 
-	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
-
-	if (ds->ds_phys->ds_next_snap_obj != 0) {
-		blkptr_t bp;
+	if (dsl_dataset_is_snapshot(ds)) {
 		dsl_dataset_t *ds_next;
-		uint64_t itor = 0;
 		uint64_t old_unique;
-		int64_t used = 0, compressed = 0, uncompressed = 0;
+		uint64_t used = 0, comp = 0, uncomp = 0;
 
 		VERIFY(0 == dsl_dataset_hold_obj(dp,
 		    ds->ds_phys->ds_next_snap_obj, FTAG, &ds_next));
 		ASSERT3U(ds_next->ds_phys->ds_prev_snap_obj, ==, obj);
 
-		old_unique = dsl_dataset_unique(ds_next);
+		old_unique = ds_next->ds_phys->ds_unique_bytes;
 
 		dmu_buf_will_dirty(ds_next->ds_dbuf, tx);
 		ds_next->ds_phys->ds_prev_snap_obj =
@@ -1788,53 +1709,49 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
 		    ds_prev ? ds_prev->ds_phys->ds_creation_txg : 0);
 
-		/*
-		 * Transfer to our deadlist (which will become next's
-		 * new deadlist) any entries from next's current
-		 * deadlist which were born before prev, and free the
-		 * other entries.
-		 *
-		 * XXX we're doing this long task with the config lock held
-		 */
-		while (bplist_iterate(&ds_next->ds_deadlist, &itor, &bp) == 0) {
-			if (bp.blk_birth <= ds->ds_phys->ds_prev_snap_txg) {
-				VERIFY(0 == bplist_enqueue(&ds->ds_deadlist,
-				    &bp, tx));
-				if (ds_prev && !after_branch_point &&
-				    bp.blk_birth >
-				    ds_prev->ds_phys->ds_prev_snap_txg) {
-					ds_prev->ds_phys->ds_unique_bytes +=
-					    bp_get_dasize(dp->dp_spa, &bp);
-				}
-			} else {
-				used += bp_get_dasize(dp->dp_spa, &bp);
-				compressed += BP_GET_PSIZE(&bp);
-				uncompressed += BP_GET_UCSIZE(&bp);
-				/* XXX check return value? */
-				(void) dsl_free(zio, dp, tx->tx_txg,
-				    &bp, NULL, NULL, ARC_NOWAIT);
-			}
-		}
 
-		ASSERT3U(used, ==, ds->ds_phys->ds_unique_bytes);
+		if (ds_next->ds_deadlist.dl_oldfmt) {
+			process_old_deadlist(ds, ds_prev, ds_next,
+			    after_branch_point, tx);
+		} else {
+			/* Adjust prev's unique space. */
+			if (ds_prev && !after_branch_point) {
+				dsl_deadlist_space_range(&ds_next->ds_deadlist,
+				    ds_prev->ds_phys->ds_prev_snap_txg,
+				    ds->ds_phys->ds_prev_snap_txg,
+				    &used, &comp, &uncomp);
+				ds_prev->ds_phys->ds_unique_bytes += used;
+			}
 
-		/* change snapused */
-		dsl_dir_diduse_space(ds->ds_dir, DD_USED_SNAP,
-		    -used, -compressed, -uncompressed, tx);
+			/* Adjust snapused. */
+			dsl_deadlist_space_range(&ds_next->ds_deadlist,
+			    ds->ds_phys->ds_prev_snap_txg, UINT64_MAX,
+			    &used, &comp, &uncomp);
+			dsl_dir_diduse_space(ds->ds_dir, DD_USED_SNAP,
+			    -used, -comp, -uncomp, tx);
+
+			/* Move blocks to be freed to pool's free list. */
+			dsl_deadlist_move_bpobj(&ds_next->ds_deadlist,
+			    &dp->dp_free_bpobj, ds->ds_phys->ds_prev_snap_txg,
+			    tx);
+			dsl_dir_diduse_space(tx->tx_pool->dp_free_dir,
+			    DD_USED_HEAD, used, comp, uncomp, tx);
+			dsl_dir_dirty(tx->tx_pool->dp_free_dir, tx);
+
+			/* Merge our deadlist into next's and free it. */
+			dsl_deadlist_merge(&ds_next->ds_deadlist,
+			    ds->ds_phys->ds_deadlist_obj, tx);
+		}
+		dsl_deadlist_close(&ds->ds_deadlist);
+		dsl_deadlist_free(mos, ds->ds_phys->ds_deadlist_obj, tx);
 
-		/* free next's deadlist */
-		bplist_close(&ds_next->ds_deadlist);
-		bplist_destroy(mos, ds_next->ds_phys->ds_deadlist_obj, tx);
+		/* Collapse range in clone heads */
+		dsl_dataset_remove_clones_key(ds,
+		    ds->ds_phys->ds_creation_txg, tx);
 
-		/* set next's deadlist to our deadlist */
-		bplist_close(&ds->ds_deadlist);
-		ds_next->ds_phys->ds_deadlist_obj =
-		    ds->ds_phys->ds_deadlist_obj;
-		VERIFY(0 == bplist_open(&ds_next->ds_deadlist, mos,
-		    ds_next->ds_phys->ds_deadlist_obj));
-		ds->ds_phys->ds_deadlist_obj = 0;
+		if (dsl_dataset_is_snapshot(ds_next)) {
+			dsl_dataset_t *ds_nextnext;
 
-		if (ds_next->ds_phys->ds_next_snap_obj != 0) {
 			/*
 			 * Update next's unique to include blocks which
 			 * were previously shared by only this snapshot
@@ -1843,25 +1760,27 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 			 * died after the next snap and before the one
 			 * after that (ie. be on the snap after next's
 			 * deadlist).
-			 *
-			 * XXX we're doing this long task with the
-			 * config lock held
 			 */
-			dsl_dataset_t *ds_after_next;
-			uint64_t space;
-
 			VERIFY(0 == dsl_dataset_hold_obj(dp,
 			    ds_next->ds_phys->ds_next_snap_obj,
-			    FTAG, &ds_after_next));
-
-			VERIFY(0 ==
-			    bplist_space_birthrange(&ds_after_next->ds_deadlist,
+			    FTAG, &ds_nextnext));
+			dsl_deadlist_space_range(&ds_nextnext->ds_deadlist,
 			    ds->ds_phys->ds_prev_snap_txg,
-			    ds->ds_phys->ds_creation_txg, &space));
-			ds_next->ds_phys->ds_unique_bytes += space;
-
-			dsl_dataset_rele(ds_after_next, FTAG);
+			    ds->ds_phys->ds_creation_txg,
+			    &used, &comp, &uncomp);
+			ds_next->ds_phys->ds_unique_bytes += used;
+			dsl_dataset_rele(ds_nextnext, FTAG);
 			ASSERT3P(ds_next->ds_prev, ==, NULL);
+
+			/* Collapse range in this head. */
+			dsl_dataset_t *hds;
+			VERIFY3U(0, ==, dsl_dataset_hold_obj(dp,
+			    ds->ds_dir->dd_phys->dd_head_dataset_obj,
+			    FTAG, &hds));
+			dsl_deadlist_remove_key(&hds->ds_deadlist,
+			    ds->ds_phys->ds_creation_txg, tx);
+			dsl_dataset_rele(hds, FTAG);
+
 		} else {
 			ASSERT3P(ds_next->ds_prev, ==, ds);
 			dsl_dataset_drop_ref(ds_next->ds_prev, ds_next);
@@ -1901,9 +1820,8 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		 */
 		struct killarg ka;
 
-		ASSERT(after_branch_point || bplist_empty(&ds->ds_deadlist));
-		bplist_close(&ds->ds_deadlist);
-		bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
+		dsl_deadlist_close(&ds->ds_deadlist);
+		dsl_deadlist_free(mos, ds->ds_phys->ds_deadlist_obj, tx);
 		ds->ds_phys->ds_deadlist_obj = 0;
 
 		/*
@@ -1914,17 +1832,23 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		 * freed all the objects in open context.
 		 */
 		ka.ds = ds;
-		ka.zio = zio;
 		ka.tx = tx;
 		err = traverse_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
 		    TRAVERSE_POST, kill_blkptr, &ka);
 		ASSERT3U(err, ==, 0);
 		ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) ||
 		    ds->ds_phys->ds_unique_bytes == 0);
-	}
 
-	err = zio_wait(zio);
-	ASSERT3U(err, ==, 0);
+		if (ds->ds_prev != NULL) {
+			if (spa_version(dp->dp_spa) >= SPA_VERSION_DIR_CLONES) {
+				VERIFY3U(0, ==, zap_remove_int(mos,
+				    ds->ds_prev->ds_dir->dd_phys->dd_clones,
+				    ds->ds_object, tx));
+			}
+			dsl_dataset_rele(ds->ds_prev, ds);
+			ds->ds_prev = ds_prev = NULL;
+		}
+	}
 
 	if (ds->ds_dir->dd_phys->dd_head_dataset_obj == ds->ds_object) {
 		/* Erase the link in the dir */
@@ -1959,8 +1883,8 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		dsl_dataset_rele(ds_prev, FTAG);
 
 	spa_prop_clear_bootfs(dp->dp_spa, ds->ds_object, tx);
-	spa_history_internal_log(LOG_DS_DESTROY, dp->dp_spa, tx,
-	    cr, "dataset = %llu", ds->ds_object);
+	spa_history_log_internal(LOG_DS_DESTROY, dp->dp_spa, tx,
+	    "dataset = %llu", ds->ds_object);
 
 	if (ds->ds_phys->ds_next_clones_obj != 0) {
 		uint64_t count;
@@ -1982,20 +1906,10 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		/*
 		 * Remove the origin of the clone we just destroyed.
 		 */
-		dsl_dataset_t *origin = ds->ds_prev;
 		struct dsl_ds_destroyarg ndsda = {0};
 
-		ASSERT3P(origin, ==, dsda->rm_origin);
-		if (origin->ds_user_ptr) {
-			origin->ds_user_evict_func(origin, origin->ds_user_ptr);
-			origin->ds_user_ptr = NULL;
-		}
-
-		dsl_dataset_rele(origin, tag);
-		ds->ds_prev = NULL;
-
-		ndsda.ds = origin;
-		dsl_dataset_destroy_sync(&ndsda, tag, cr, tx);
+		ndsda.ds = dsda->rm_origin;
+		dsl_dataset_destroy_sync(&ndsda, tag, tx);
 	}
 }
 
@@ -2012,7 +1926,8 @@ dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
 	 * owned by the snapshot dataset must be accommodated by space
 	 * outside of the reservation.
 	 */
-	asize = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
+	ASSERT(ds->ds_reserved == 0 || DS_UNIQUE_IS_ACCURATE(ds));
+	asize = MIN(ds->ds_phys->ds_unique_bytes, ds->ds_reserved);
 	if (asize > dsl_dir_space_available(ds->ds_dir, NULL, 0, FALSE))
 		return (ENOSPC);
 
@@ -2026,7 +1941,6 @@ dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
 	return (0);
 }
 
-/* ARGSUSED */
 int
 dsl_dataset_snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
@@ -2067,7 +1981,7 @@ dsl_dataset_snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
 }
 
 void
-dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_snapshot_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
 	const char *snapname = arg2;
@@ -2125,8 +2039,8 @@ dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 			    ds->ds_prev->ds_phys->ds_creation_txg);
 			ds->ds_prev->ds_phys->ds_next_snap_obj = dsobj;
 		} else if (next_clones_obj != 0) {
-			VERIFY3U(0, ==, zap_remove_int(mos,
-			    next_clones_obj, dsphys->ds_next_snap_obj, tx));
+			remove_from_next_clones(ds->ds_prev,
+			    dsphys->ds_next_snap_obj, tx);
 			VERIFY3U(0, ==, zap_add_int(mos,
 			    next_clones_obj, dsobj, tx));
 		}
@@ -2138,25 +2052,31 @@ dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 	 * since our unique space is going to zero.
 	 */
 	if (ds->ds_reserved) {
-		int64_t add = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
+		int64_t delta;
+		ASSERT(DS_UNIQUE_IS_ACCURATE(ds));
+		delta = MIN(ds->ds_phys->ds_unique_bytes, ds->ds_reserved);
 		dsl_dir_diduse_space(ds->ds_dir, DD_USED_REFRSRV,
-		    add, 0, 0, tx);
+		    delta, 0, 0, tx);
 	}
 
-	bplist_close(&ds->ds_deadlist);
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
+	zfs_dbgmsg("taking snapshot %s@%s/%llu; newkey=%llu",
+	    ds->ds_dir->dd_myname, snapname, dsobj,
+	    ds->ds_phys->ds_prev_snap_txg);
+	ds->ds_phys->ds_deadlist_obj = dsl_deadlist_clone(&ds->ds_deadlist,
+	    UINT64_MAX, ds->ds_phys->ds_prev_snap_obj, tx);
+	dsl_deadlist_close(&ds->ds_deadlist);
+	dsl_deadlist_open(&ds->ds_deadlist, mos, ds->ds_phys->ds_deadlist_obj);
+	dsl_deadlist_add_key(&ds->ds_deadlist,
+	    ds->ds_phys->ds_prev_snap_txg, tx);
+
 	ASSERT3U(ds->ds_phys->ds_prev_snap_txg, <, tx->tx_txg);
 	ds->ds_phys->ds_prev_snap_obj = dsobj;
 	ds->ds_phys->ds_prev_snap_txg = crtxg;
 	ds->ds_phys->ds_unique_bytes = 0;
 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
-	ds->ds_phys->ds_deadlist_obj =
-	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
-	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
-	    ds->ds_phys->ds_deadlist_obj));
 
-	dprintf("snap '%s' -> obj %llu\n", snapname, dsobj);
 	err = zap_add(mos, ds->ds_phys->ds_snapnames_zapobj,
 	    snapname, 8, 1, &dsobj, tx);
 	ASSERT(err == 0);
@@ -2166,9 +2086,11 @@ dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 	VERIFY(0 == dsl_dataset_get_ref(dp,
 	    ds->ds_phys->ds_prev_snap_obj, ds, &ds->ds_prev));
 
-	dsl_pool_ds_snapshotted(ds, tx);
+	dsl_scan_ds_snapshotted(ds, tx);
+
+	dsl_dir_snap_cmtime_update(ds->ds_dir);
 
-	spa_history_internal_log(LOG_DS_SNAPSHOT, dp->dp_spa, tx, cr,
+	spa_history_log_internal(LOG_DS_SNAPSHOT, dp->dp_spa, tx,
 	    "dataset = %llu", dsobj);
 }
 
@@ -2176,7 +2098,7 @@ void
 dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
 {
 	ASSERT(dmu_tx_is_syncing(tx));
-	ASSERT(ds->ds_user_ptr != NULL);
+	ASSERT(ds->ds_objset != NULL);
 	ASSERT(ds->ds_phys->ds_next_snap_obj == 0);
 
 	/*
@@ -2187,7 +2109,7 @@ dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
 	ds->ds_phys->ds_fsid_guid = ds->ds_fsid_guid;
 
 	dsl_dir_dirty(ds->ds_dir, tx);
-	dmu_objset_sync(ds->ds_user_ptr, zio, tx);
+	dmu_objset_sync(ds->ds_objset, zio, tx);
 }
 
 void
@@ -2211,7 +2133,12 @@ dsl_dataset_stats(dsl_dataset_t *ds, nvlist_t *nv)
 	    ds->ds_reserved);
 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_GUID,
 	    ds->ds_phys->ds_guid);
-	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERREFS, ds->ds_userrefs);
+	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_UNIQUE,
+	    ds->ds_phys->ds_unique_bytes);
+	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_OBJSETID,
+	    ds->ds_object);
+	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERREFS,
+	    ds->ds_userrefs);
 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_DEFER_DESTROY,
 	    DS_IS_DEFER_DESTROY(ds) ? 1 : 0);
 
@@ -2335,8 +2262,7 @@ dsl_dataset_snapshot_rename_check(void *arg1, void *arg2, dmu_tx_t *tx)
 }
 
 static void
-dsl_dataset_snapshot_rename_sync(void *arg1, void *arg2,
-    cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_snapshot_rename_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
 	const char *newsnapname = arg2;
@@ -2360,8 +2286,8 @@ dsl_dataset_snapshot_rename_sync(void *arg1, void *arg2,
 	    ds->ds_snapname, 8, 1, &ds->ds_object, tx);
 	ASSERT3U(err, ==, 0);
 
-	spa_history_internal_log(LOG_DS_RENAME, dd->dd_pool->dp_spa, tx,
-	    cr, "dataset = %llu", ds->ds_object);
+	spa_history_log_internal(LOG_DS_RENAME, dd->dd_pool->dp_spa, tx,
+	    "dataset = %llu", ds->ds_object);
 	dsl_dataset_rele(hds, FTAG);
 }
 
@@ -2373,43 +2299,36 @@ struct renamesnaparg {
 };
 
 static int
-dsl_snapshot_rename_one(char *name, void *arg)
+dsl_snapshot_rename_one(const char *name, void *arg)
 {
 	struct renamesnaparg *ra = arg;
 	dsl_dataset_t *ds = NULL;
-	char *cp;
+	char *snapname;
 	int err;
 
-	cp = name + strlen(name);
-	*cp = '@';
-	(void) strcpy(cp + 1, ra->oldsnap);
+	snapname = kmem_asprintf("%s@%s", name, ra->oldsnap);
+	(void) strlcpy(ra->failed, snapname, sizeof (ra->failed));
 
 	/*
 	 * For recursive snapshot renames the parent won't be changing
 	 * so we just pass name for both the to/from argument.
 	 */
-	err = zfs_secpolicy_rename_perms(name, name, CRED());
-	if (err == ENOENT) {
-		return (0);
-	} else if (err) {
-		(void) strcpy(ra->failed, name);
-		return (err);
+	err = zfs_secpolicy_rename_perms(snapname, snapname, CRED());
+	if (err != 0) {
+		strfree(snapname);
+		return (err == ENOENT ? 0 : err);
 	}
 
 #ifdef _KERNEL
 	/*
 	 * For all filesystems undergoing rename, we'll need to unmount it.
 	 */
-	(void) zfs_unmount_snap(name, NULL);
+	(void) zfs_unmount_snap(snapname, NULL);
 #endif
-	err = dsl_dataset_hold(name, ra->dstg, &ds);
-	*cp = '\0';
-	if (err == ENOENT) {
-		return (0);
-	} else if (err) {
-		(void) strcpy(ra->failed, name);
-		return (err);
-	}
+	err = dsl_dataset_hold(snapname, ra->dstg, &ds);
+	strfree(snapname);
+	if (err != 0)
+		return (err == ENOENT ? 0 : err);
 
 	dsl_sync_task_create(ra->dstg, dsl_dataset_snapshot_rename_check,
 	    dsl_dataset_snapshot_rename_sync, ds, ra->newsnap, 0);
@@ -2425,7 +2344,7 @@ dsl_recursive_rename(char *oldname, const char *newname)
 	dsl_sync_task_t *dst;
 	spa_t *spa;
 	char *cp, *fsname = spa_strdup(oldname);
-	int len = strlen(oldname);
+	int len = strlen(oldname) + 1;
 
 	/* truncate the snapshot name to get the fsname */
 	cp = strchr(fsname, '@');
@@ -2433,7 +2352,7 @@ dsl_recursive_rename(char *oldname, const char *newname)
 
 	err = spa_open(fsname, &spa, FTAG);
 	if (err) {
-		kmem_free(fsname, len + 1);
+		kmem_free(fsname, len);
 		return (err);
 	}
 	ra = kmem_alloc(sizeof (struct renamesnaparg), KM_SLEEP);
@@ -2445,7 +2364,7 @@ dsl_recursive_rename(char *oldname, const char *newname)
 
 	err = dmu_objset_find(fsname, dsl_snapshot_rename_one, ra,
 	    DS_FIND_CHILDREN);
-	kmem_free(fsname, len + 1);
+	kmem_free(fsname, len);
 
 	if (err == 0) {
 		err = dsl_sync_task_group_wait(ra->dstg);
@@ -2456,14 +2375,15 @@ dsl_recursive_rename(char *oldname, const char *newname)
 		dsl_dataset_t *ds = dst->dst_arg1;
 		if (dst->dst_err) {
 			dsl_dir_name(ds->ds_dir, ra->failed);
-			(void) strcat(ra->failed, "@");
-			(void) strcat(ra->failed, ra->newsnap);
+			(void) strlcat(ra->failed, "@", sizeof (ra->failed));
+			(void) strlcat(ra->failed, ra->newsnap,
+			    sizeof (ra->failed));
 		}
 		dsl_dataset_rele(ds, ra->dstg);
 	}
 
 	if (err)
-		(void) strcpy(oldname, ra->failed);
+		(void) strlcpy(oldname, ra->failed, sizeof (ra->failed));
 
 	dsl_sync_task_group_destroy(ra->dstg);
 	kmem_free(ra, sizeof (struct renamesnaparg));
@@ -2472,7 +2392,7 @@ dsl_recursive_rename(char *oldname, const char *newname)
 }
 
 static int
-dsl_valid_rename(char *oldname, void *arg)
+dsl_valid_rename(const char *oldname, void *arg)
 {
 	int delta = *(int *)arg;
 
@@ -2494,12 +2414,7 @@ dsl_dataset_rename(char *oldname, const char *newname, boolean_t recursive)
 	err = dsl_dir_open(oldname, FTAG, &dd, &tail);
 	if (err)
 		return (err);
-	/*
-	 * If there are more than 2 references there may be holds
-	 * hanging around that haven't been cleared out yet.
-	 */
-	if (dmu_buf_refcount(dd->dd_dbuf) > 2)
-		txg_wait_synced(dd->dd_pool, 0);
+
 	if (tail == NULL) {
 		int delta = strlen(newname) - strlen(oldname);
 
@@ -2508,13 +2423,14 @@ dsl_dataset_rename(char *oldname, const char *newname, boolean_t recursive)
 			err = dmu_objset_find(oldname, dsl_valid_rename,
 			    &delta, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
 
-		if (!err)
+		if (err == 0)
 			err = dsl_dir_rename(dd, newname);
 		dsl_dir_close(dd, FTAG);
 		return (err);
 	}
+
 	if (tail[0] != '@') {
-		/* the name ended in a nonexistant component */
+		/* the name ended in a nonexistent component */
 		dsl_dir_close(dd, FTAG);
 		return (ENOENT);
 	}
@@ -2553,13 +2469,14 @@ struct promotenode {
 
 struct promotearg {
 	list_t shared_snaps, origin_snaps, clone_snaps;
-	dsl_dataset_t *origin_origin, *origin_head;
+	dsl_dataset_t *origin_origin;
 	uint64_t used, comp, uncomp, unique, cloneusedsnap, originusedsnap;
+	char *err_ds;
 };
 
 static int snaplist_space(list_t *l, uint64_t mintxg, uint64_t *spacep);
+static boolean_t snaplist_unstable(list_t *l);
 
-/* ARGSUSED */
 static int
 dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
@@ -2568,6 +2485,7 @@ dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	struct promotenode *snap = list_head(&pa->shared_snaps);
 	dsl_dataset_t *origin_ds = snap->ds;
 	int err;
+	uint64_t unused;
 
 	/* Check that it is a real clone */
 	if (!dsl_dir_is_clone(hds->ds_dir))
@@ -2583,10 +2501,9 @@ dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	/* compute origin's new unique space */
 	snap = list_tail(&pa->clone_snaps);
 	ASSERT3U(snap->ds->ds_phys->ds_prev_snap_obj, ==, origin_ds->ds_object);
-	err = bplist_space_birthrange(&snap->ds->ds_deadlist,
-	    origin_ds->ds_phys->ds_prev_snap_txg, UINT64_MAX, &pa->unique);
-	if (err)
-		return (err);
+	dsl_deadlist_space_range(&snap->ds->ds_deadlist,
+	    origin_ds->ds_phys->ds_prev_snap_txg, UINT64_MAX,
+	    &pa->unique, &unused, &unused);
 
 	/*
 	 * Walk the snapshots that we are moving
@@ -2614,18 +2531,19 @@ dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
 		/* Check that the snapshot name does not conflict */
 		VERIFY(0 == dsl_dataset_get_snapname(ds));
 		err = dsl_dataset_snap_lookup(hds, ds->ds_snapname, &val);
-		if (err == 0)
-			return (EEXIST);
+		if (err == 0) {
+			err = EEXIST;
+			goto out;
+		}
 		if (err != ENOENT)
-			return (err);
+			goto out;
 
 		/* The very first snapshot does not have a deadlist */
 		if (ds->ds_phys->ds_prev_snap_obj == 0)
 			continue;
 
-		if (err = bplist_space(&ds->ds_deadlist,
-		    &dlused, &dlcomp, &dluncomp))
-			return (err);
+		dsl_deadlist_space(&ds->ds_deadlist,
+		    &dlused, &dlcomp, &dluncomp);
 		pa->used += dlused;
 		pa->comp += dlcomp;
 		pa->uncomp += dluncomp;
@@ -2658,19 +2576,19 @@ dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
 
 		/*
 		 * Note, typically this will not be a clone of a clone,
-		 * so snap->ds->ds_origin_txg will be < TXG_INITIAL, so
-		 * these snaplist_space() -> bplist_space_birthrange()
+		 * so dd_origin_txg will be < TXG_INITIAL, so
+		 * these snaplist_space() -> dsl_deadlist_space_range()
 		 * calls will be fast because they do not have to
 		 * iterate over all bps.
 		 */
 		snap = list_head(&pa->origin_snaps);
 		err = snaplist_space(&pa->shared_snaps,
-		    snap->ds->ds_origin_txg, &pa->cloneusedsnap);
+		    snap->ds->ds_dir->dd_origin_txg, &pa->cloneusedsnap);
 		if (err)
 			return (err);
 
 		err = snaplist_space(&pa->clone_snaps,
-		    snap->ds->ds_origin_txg, &space);
+		    snap->ds->ds_dir->dd_origin_txg, &space);
 		if (err)
 			return (err);
 		pa->cloneusedsnap += space;
@@ -2683,10 +2601,13 @@ dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	}
 
 	return (0);
+out:
+	pa->err_ds =  snap->ds->ds_snapname;
+	return (err);
 }
 
 static void
-dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_promote_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *hds = arg1;
 	struct promotearg *pa = arg2;
@@ -2720,9 +2641,7 @@ dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 
 	/* change the origin's next clone */
 	if (origin_ds->ds_phys->ds_next_clones_obj) {
-		VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
-		    origin_ds->ds_phys->ds_next_clones_obj,
-		    origin_ds->ds_phys->ds_next_snap_obj, tx));
+		remove_from_next_clones(origin_ds, snap->ds->ds_object, tx);
 		VERIFY3U(0, ==, zap_add_int(dp->dp_meta_objset,
 		    origin_ds->ds_phys->ds_next_clones_obj,
 		    oldnext_obj, tx));
@@ -2732,10 +2651,31 @@ dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
 	ASSERT3U(dd->dd_phys->dd_origin_obj, ==, origin_ds->ds_object);
 	dd->dd_phys->dd_origin_obj = odd->dd_phys->dd_origin_obj;
-	hds->ds_origin_txg = origin_head->ds_origin_txg;
+	dd->dd_origin_txg = origin_head->ds_dir->dd_origin_txg;
 	dmu_buf_will_dirty(odd->dd_dbuf, tx);
 	odd->dd_phys->dd_origin_obj = origin_ds->ds_object;
-	origin_head->ds_origin_txg = origin_ds->ds_phys->ds_creation_txg;
+	origin_head->ds_dir->dd_origin_txg =
+	    origin_ds->ds_phys->ds_creation_txg;
+
+	/* change dd_clone entries */
+	if (spa_version(dp->dp_spa) >= SPA_VERSION_DIR_CLONES) {
+		VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
+		    odd->dd_phys->dd_clones, hds->ds_object, tx));
+		VERIFY3U(0, ==, zap_add_int(dp->dp_meta_objset,
+		    pa->origin_origin->ds_dir->dd_phys->dd_clones,
+		    hds->ds_object, tx));
+
+		VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
+		    pa->origin_origin->ds_dir->dd_phys->dd_clones,
+		    origin_head->ds_object, tx));
+		if (dd->dd_phys->dd_clones == 0) {
+			dd->dd_phys->dd_clones = zap_create(dp->dp_meta_objset,
+			    DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
+		}
+		VERIFY3U(0, ==, zap_add_int(dp->dp_meta_objset,
+		    dd->dd_phys->dd_clones, origin_head->ds_object, tx));
+
+	}
 
 	/* move snapshots to this dir */
 	for (snap = list_head(&pa->shared_snaps); snap;
@@ -2743,9 +2683,9 @@ dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 		dsl_dataset_t *ds = snap->ds;
 
 		/* unregister props as dsl_dir is changing */
-		if (ds->ds_user_ptr) {
-			ds->ds_user_evict_func(ds, ds->ds_user_ptr);
-			ds->ds_user_ptr = NULL;
+		if (ds->ds_objset) {
+			dmu_objset_evict(ds->ds_objset);
+			ds->ds_objset = NULL;
 		}
 		/* move snap name entry */
 		VERIFY(0 == dsl_dataset_get_snapname(ds));
@@ -2754,6 +2694,7 @@ dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 		VERIFY(0 == zap_add(dp->dp_meta_objset,
 		    hds->ds_phys->ds_snapnames_zapobj, ds->ds_snapname,
 		    8, 1, &ds->ds_object, tx));
+
 		/* change containing dsl_dir */
 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
 		ASSERT3U(ds->ds_phys->ds_dir_obj, ==, odd->dd_object);
@@ -2763,6 +2704,40 @@ dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 		VERIFY(0 == dsl_dir_open_obj(dp, dd->dd_object,
 		    NULL, ds, &ds->ds_dir));
 
+		/* move any clone references */
+		if (ds->ds_phys->ds_next_clones_obj &&
+		    spa_version(dp->dp_spa) >= SPA_VERSION_DIR_CLONES) {
+			zap_cursor_t zc;
+			zap_attribute_t za;
+
+			for (zap_cursor_init(&zc, dp->dp_meta_objset,
+			    ds->ds_phys->ds_next_clones_obj);
+			    zap_cursor_retrieve(&zc, &za) == 0;
+			    zap_cursor_advance(&zc)) {
+				dsl_dataset_t *cnds;
+				uint64_t o;
+
+				if (za.za_first_integer == oldnext_obj) {
+					/*
+					 * We've already moved the
+					 * origin's reference.
+					 */
+					continue;
+				}
+
+				VERIFY3U(0, ==, dsl_dataset_hold_obj(dp,
+				    za.za_first_integer, FTAG, &cnds));
+				o = cnds->ds_dir->dd_phys->dd_head_dataset_obj;
+
+				VERIFY3U(zap_remove_int(dp->dp_meta_objset,
+				    odd->dd_phys->dd_clones, o, tx), ==, 0);
+				VERIFY3U(zap_add_int(dp->dp_meta_objset,
+				    dd->dd_phys->dd_clones, o, tx), ==, 0);
+				dsl_dataset_rele(cnds, FTAG);
+			}
+			zap_cursor_fini(&zc);
+		}
+
 		ASSERT3U(dsl_prop_numcb(ds), ==, 0);
 	}
 
@@ -2792,8 +2767,8 @@ dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 	origin_ds->ds_phys->ds_unique_bytes = pa->unique;
 
 	/* log history record */
-	spa_history_internal_log(LOG_DS_PROMOTE, dd->dd_pool->dp_spa, tx,
-	    cr, "dataset = %llu", hds->ds_object);
+	spa_history_log_internal(LOG_DS_PROMOTE, dd->dd_pool->dp_spa, tx,
+	    "dataset = %llu", hds->ds_object);
 
 	dsl_dir_close(odd, FTAG);
 }
@@ -2858,11 +2833,9 @@ snaplist_space(list_t *l, uint64_t mintxg, uint64_t *spacep)
 
 	*spacep = 0;
 	for (snap = list_head(l); snap; snap = list_next(l, snap)) {
-		uint64_t used;
-		int err = bplist_space_birthrange(&snap->ds->ds_deadlist,
-		    mintxg, UINT64_MAX, &used);
-		if (err)
-			return (err);
+		uint64_t used, comp, uncomp;
+		dsl_deadlist_space_range(&snap->ds->ds_deadlist,
+		    mintxg, UINT64_MAX, &used, &comp, &uncomp);
 		*spacep += used;
 	}
 	return (0);
@@ -2897,7 +2870,7 @@ snaplist_destroy(list_t *l, boolean_t own)
  * NULL, indicating that the clone is not a clone of a clone).
  */
 int
-dsl_dataset_promote(const char *name)
+dsl_dataset_promote(const char *name, char *conflsnap)
 {
 	dsl_dataset_t *ds;
 	dsl_dir_t *dd;
@@ -2949,10 +2922,10 @@ dsl_dataset_promote(const char *name)
 	if (err != 0)
 		goto out;
 
-	if (dsl_dir_is_clone(snap->ds->ds_dir)) {
-		err = dsl_dataset_own_obj(dp,
+	if (snap->ds->ds_dir->dd_phys->dd_origin_obj != 0) {
+		err = dsl_dataset_hold_obj(dp,
 		    snap->ds->ds_dir->dd_phys->dd_origin_obj,
-		    0, FTAG, &pa.origin_origin);
+		    FTAG, &pa.origin_origin);
 		if (err != 0)
 			goto out;
 	}
@@ -2968,14 +2941,16 @@ out:
 	if (err == 0) {
 		err = dsl_sync_task_do(dp, dsl_dataset_promote_check,
 		    dsl_dataset_promote_sync, ds, &pa,
-		    2 + 2 * doi.doi_physical_blks);
+		    2 + 2 * doi.doi_physical_blocks_512);
+		if (err && pa.err_ds && conflsnap)
+			(void) strncpy(conflsnap, pa.err_ds, MAXNAMELEN);
 	}
 
 	snaplist_destroy(&pa.shared_snaps, B_TRUE);
 	snaplist_destroy(&pa.clone_snaps, B_FALSE);
 	snaplist_destroy(&pa.origin_snaps, B_FALSE);
 	if (pa.origin_origin)
-		dsl_dataset_disown(pa.origin_origin, FTAG);
+		dsl_dataset_rele(pa.origin_origin, FTAG);
 	dsl_dataset_rele(ds, FTAG);
 	return (err);
 }
@@ -3002,9 +2977,11 @@ dsl_dataset_clone_swap_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	if (csa->cds->ds_prev != csa->ohds->ds_prev)
 		return (EINVAL);
 
-	/* cds should be the clone */
-	if (csa->cds->ds_prev->ds_phys->ds_next_snap_obj !=
-	    csa->ohds->ds_object)
+	/* cds should be the clone (unless they are unrelated) */
+	if (csa->cds->ds_prev != NULL &&
+	    csa->cds->ds_prev != csa->cds->ds_dir->dd_pool->dp_origin_snap &&
+	    csa->ohds->ds_object !=
+	    csa->cds->ds_prev->ds_phys->ds_next_snap_obj)
 		return (EINVAL);
 
 	/* the clone should be a child of the origin */
@@ -3027,38 +3004,49 @@ dsl_dataset_clone_swap_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	    dsl_dir_space_available(csa->ohds->ds_dir, NULL, 0, TRUE))
 		return (ENOSPC);
 
+	if (csa->ohds->ds_quota != 0 &&
+	    csa->cds->ds_phys->ds_unique_bytes > csa->ohds->ds_quota)
+		return (EDQUOT);
+
 	return (0);
 }
 
 /* ARGSUSED */
 static void
-dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_clone_swap_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	struct cloneswaparg *csa = arg1;
 	dsl_pool_t *dp = csa->cds->ds_dir->dd_pool;
 
 	ASSERT(csa->cds->ds_reserved == 0);
-	ASSERT(csa->cds->ds_quota == csa->ohds->ds_quota);
+	ASSERT(csa->ohds->ds_quota == 0 ||
+	    csa->cds->ds_phys->ds_unique_bytes <= csa->ohds->ds_quota);
 
 	dmu_buf_will_dirty(csa->cds->ds_dbuf, tx);
 	dmu_buf_will_dirty(csa->ohds->ds_dbuf, tx);
-	dmu_buf_will_dirty(csa->cds->ds_prev->ds_dbuf, tx);
 
-	if (csa->cds->ds_user_ptr != NULL) {
-		csa->cds->ds_user_evict_func(csa->cds, csa->cds->ds_user_ptr);
-		csa->cds->ds_user_ptr = NULL;
+	if (csa->cds->ds_objset != NULL) {
+		dmu_objset_evict(csa->cds->ds_objset);
+		csa->cds->ds_objset = NULL;
 	}
 
-	if (csa->ohds->ds_user_ptr != NULL) {
-		csa->ohds->ds_user_evict_func(csa->ohds,
-		    csa->ohds->ds_user_ptr);
-		csa->ohds->ds_user_ptr = NULL;
+	if (csa->ohds->ds_objset != NULL) {
+		dmu_objset_evict(csa->ohds->ds_objset);
+		csa->ohds->ds_objset = NULL;
 	}
 
-	/* reset origin's unique bytes */
-	VERIFY(0 == bplist_space_birthrange(&csa->cds->ds_deadlist,
-	    csa->cds->ds_prev->ds_phys->ds_prev_snap_txg, UINT64_MAX,
-	    &csa->cds->ds_prev->ds_phys->ds_unique_bytes));
+	/*
+	 * Reset origin's unique bytes, if it exists.
+	 */
+	if (csa->cds->ds_prev) {
+		dsl_dataset_t *origin = csa->cds->ds_prev;
+		uint64_t comp, uncomp;
+
+		dmu_buf_will_dirty(origin->ds_dbuf, tx);
+		dsl_deadlist_space_range(&csa->cds->ds_deadlist,
+		    origin->ds_phys->ds_prev_snap_txg, UINT64_MAX,
+		    &origin->ds_phys->ds_unique_bytes, &comp, &uncomp);
+	}
 
 	/* swap blkptrs */
 	{
@@ -3077,10 +3065,10 @@ dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 		ASSERT3U(csa->cds->ds_dir->dd_phys->
 		    dd_used_breakdown[DD_USED_SNAP], ==, 0);
 
-		VERIFY(0 == bplist_space(&csa->cds->ds_deadlist, &cdl_used,
-		    &cdl_comp, &cdl_uncomp));
-		VERIFY(0 == bplist_space(&csa->ohds->ds_deadlist, &odl_used,
-		    &odl_comp, &odl_uncomp));
+		dsl_deadlist_space(&csa->cds->ds_deadlist,
+		    &cdl_used, &cdl_comp, &cdl_uncomp);
+		dsl_deadlist_space(&csa->ohds->ds_deadlist,
+		    &odl_used, &odl_comp, &odl_uncomp);
 
 		dused = csa->cds->ds_phys->ds_used_bytes + cdl_used -
 		    (csa->ohds->ds_phys->ds_used_bytes + odl_used);
@@ -3101,21 +3089,16 @@ dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 		 * deadlist (since that's the only thing that's
 		 * changing that affects the snapused).
 		 */
-		VERIFY(0 == bplist_space_birthrange(&csa->cds->ds_deadlist,
-		    csa->ohds->ds_origin_txg, UINT64_MAX, &cdl_used));
-		VERIFY(0 == bplist_space_birthrange(&csa->ohds->ds_deadlist,
-		    csa->ohds->ds_origin_txg, UINT64_MAX, &odl_used));
+		dsl_deadlist_space_range(&csa->cds->ds_deadlist,
+		    csa->ohds->ds_dir->dd_origin_txg, UINT64_MAX,
+		    &cdl_used, &cdl_comp, &cdl_uncomp);
+		dsl_deadlist_space_range(&csa->ohds->ds_deadlist,
+		    csa->ohds->ds_dir->dd_origin_txg, UINT64_MAX,
+		    &odl_used, &odl_comp, &odl_uncomp);
 		dsl_dir_transfer_space(csa->ohds->ds_dir, cdl_used - odl_used,
 		    DD_USED_HEAD, DD_USED_SNAP, tx);
 	}
 
-#define	SWITCH64(x, y) \
-	{ \
-		uint64_t __tmp = (x); \
-		(x) = (y); \
-		(y) = __tmp; \
-	}
-
 	/* swap ds_*_bytes */
 	SWITCH64(csa->ohds->ds_phys->ds_used_bytes,
 	    csa->cds->ds_phys->ds_used_bytes);
@@ -3130,22 +3113,26 @@ dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 	dsl_dir_diduse_space(csa->ohds->ds_dir, DD_USED_REFRSRV,
 	    csa->unused_refres_delta, 0, 0, tx);
 
-	/* swap deadlists */
-	bplist_close(&csa->cds->ds_deadlist);
-	bplist_close(&csa->ohds->ds_deadlist);
+	/*
+	 * Swap deadlists.
+	 */
+	dsl_deadlist_close(&csa->cds->ds_deadlist);
+	dsl_deadlist_close(&csa->ohds->ds_deadlist);
 	SWITCH64(csa->ohds->ds_phys->ds_deadlist_obj,
 	    csa->cds->ds_phys->ds_deadlist_obj);
-	VERIFY(0 == bplist_open(&csa->cds->ds_deadlist, dp->dp_meta_objset,
-	    csa->cds->ds_phys->ds_deadlist_obj));
-	VERIFY(0 == bplist_open(&csa->ohds->ds_deadlist, dp->dp_meta_objset,
-	    csa->ohds->ds_phys->ds_deadlist_obj));
+	dsl_deadlist_open(&csa->cds->ds_deadlist, dp->dp_meta_objset,
+	    csa->cds->ds_phys->ds_deadlist_obj);
+	dsl_deadlist_open(&csa->ohds->ds_deadlist, dp->dp_meta_objset,
+	    csa->ohds->ds_phys->ds_deadlist_obj);
 
-	dsl_pool_ds_clone_swapped(csa->ohds, csa->cds, tx);
+	dsl_scan_ds_clone_swapped(csa->ohds, csa->cds, tx);
 }
 
 /*
- * Swap 'clone' with its origin head file system.  Used at the end
- * of "online recv" to swizzle the file system to the new version.
+ * Swap 'clone' with its origin head datasets.  Used at the end of "zfs
+ * recv" into an existing fs to swizzle the file system to the new
+ * version, and by "zfs rollback".  Can also be used to swap two
+ * independent head datasets if neither has any snapshots.
  */
 int
 dsl_dataset_clone_swap(dsl_dataset_t *clone, dsl_dataset_t *origin_head,
@@ -3254,62 +3241,70 @@ static int
 dsl_dataset_set_quota_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
-	uint64_t *quotap = arg2;
-	uint64_t new_quota = *quotap;
+	dsl_prop_setarg_t *psa = arg2;
+	int err;
 
 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) < SPA_VERSION_REFQUOTA)
 		return (ENOTSUP);
 
-	if (new_quota == 0)
+	if ((err = dsl_prop_predict_sync(ds->ds_dir, psa)) != 0)
+		return (err);
+
+	if (psa->psa_effective_value == 0)
 		return (0);
 
-	if (new_quota < ds->ds_phys->ds_used_bytes ||
-	    new_quota < ds->ds_reserved)
+	if (psa->psa_effective_value < ds->ds_phys->ds_used_bytes ||
+	    psa->psa_effective_value < ds->ds_reserved)
 		return (ENOSPC);
 
 	return (0);
 }
 
-/* ARGSUSED */
+extern void dsl_prop_set_sync(void *, void *, dmu_tx_t *);
+
 void
-dsl_dataset_set_quota_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_set_quota_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
-	uint64_t *quotap = arg2;
-	uint64_t new_quota = *quotap;
+	dsl_prop_setarg_t *psa = arg2;
+	uint64_t effective_value = psa->psa_effective_value;
 
-	dmu_buf_will_dirty(ds->ds_dbuf, tx);
-
-	ds->ds_quota = new_quota;
+	dsl_prop_set_sync(ds, psa, tx);
+	DSL_PROP_CHECK_PREDICTION(ds->ds_dir, psa);
 
-	dsl_dir_prop_set_uint64_sync(ds->ds_dir, "refquota", new_quota, cr, tx);
+	if (ds->ds_quota != effective_value) {
+		dmu_buf_will_dirty(ds->ds_dbuf, tx);
+		ds->ds_quota = effective_value;
 
-	spa_history_internal_log(LOG_DS_REFQUOTA, ds->ds_dir->dd_pool->dp_spa,
-	    tx, cr, "%lld dataset = %llu ",
-	    (longlong_t)new_quota, ds->ds_object);
+		spa_history_log_internal(LOG_DS_REFQUOTA,
+		    ds->ds_dir->dd_pool->dp_spa, tx, "%lld dataset = %llu ",
+		    (longlong_t)ds->ds_quota, ds->ds_object);
+	}
 }
 
 int
-dsl_dataset_set_quota(const char *dsname, uint64_t quota)
+dsl_dataset_set_quota(const char *dsname, zprop_source_t source, uint64_t quota)
 {
 	dsl_dataset_t *ds;
+	dsl_prop_setarg_t psa;
 	int err;
 
+	dsl_prop_setarg_init_uint64(&psa, "refquota", source, &quota);
+
 	err = dsl_dataset_hold(dsname, FTAG, &ds);
 	if (err)
 		return (err);
 
-	if (quota != ds->ds_quota) {
-		/*
-		 * If someone removes a file, then tries to set the quota, we
-		 * want to make sure the file freeing takes effect.
-		 */
-		txg_wait_open(ds->ds_dir->dd_pool, 0);
+	/*
+	 * If someone removes a file, then tries to set the quota, we
+	 * want to make sure the file freeing takes effect.
+	 */
+	txg_wait_open(ds->ds_dir->dd_pool, 0);
+
+	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
+	    dsl_dataset_set_quota_check, dsl_dataset_set_quota_sync,
+	    ds, &psa, 0);
 
-		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
-		    dsl_dataset_set_quota_check, dsl_dataset_set_quota_sync,
-		    ds, &quota, 0);
-	}
 	dsl_dataset_rele(ds, FTAG);
 	return (err);
 }
@@ -3318,9 +3313,10 @@ static int
 dsl_dataset_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
-	uint64_t *reservationp = arg2;
-	uint64_t new_reservation = *reservationp;
+	dsl_prop_setarg_t *psa = arg2;
+	uint64_t effective_value;
 	uint64_t unique;
+	int err;
 
 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) <
 	    SPA_VERSION_REFRESERVATION)
@@ -3329,6 +3325,11 @@ dsl_dataset_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	if (dsl_dataset_is_snapshot(ds))
 		return (EINVAL);
 
+	if ((err = dsl_prop_predict_sync(ds->ds_dir, psa)) != 0)
+		return (err);
+
+	effective_value = psa->psa_effective_value;
+
 	/*
 	 * If we are doing the preliminary check in open context, the
 	 * space estimates may be inaccurate.
@@ -3337,76 +3338,101 @@ dsl_dataset_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
 		return (0);
 
 	mutex_enter(&ds->ds_lock);
-	unique = dsl_dataset_unique(ds);
+	if (!DS_UNIQUE_IS_ACCURATE(ds))
+		dsl_dataset_recalc_head_uniq(ds);
+	unique = ds->ds_phys->ds_unique_bytes;
 	mutex_exit(&ds->ds_lock);
 
-	if (MAX(unique, new_reservation) > MAX(unique, ds->ds_reserved)) {
-		uint64_t delta = MAX(unique, new_reservation) -
+	if (MAX(unique, effective_value) > MAX(unique, ds->ds_reserved)) {
+		uint64_t delta = MAX(unique, effective_value) -
 		    MAX(unique, ds->ds_reserved);
 
 		if (delta > dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE))
 			return (ENOSPC);
 		if (ds->ds_quota > 0 &&
-		    new_reservation > ds->ds_quota)
+		    effective_value > ds->ds_quota)
 			return (ENOSPC);
 	}
 
 	return (0);
 }
 
-/* ARGSUSED */
 static void
-dsl_dataset_set_reservation_sync(void *arg1, void *arg2, cred_t *cr,
-    dmu_tx_t *tx)
+dsl_dataset_set_reservation_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
-	uint64_t *reservationp = arg2;
-	uint64_t new_reservation = *reservationp;
+	dsl_prop_setarg_t *psa = arg2;
+	uint64_t effective_value = psa->psa_effective_value;
 	uint64_t unique;
 	int64_t delta;
 
+	dsl_prop_set_sync(ds, psa, tx);
+	DSL_PROP_CHECK_PREDICTION(ds->ds_dir, psa);
+
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
 
 	mutex_enter(&ds->ds_dir->dd_lock);
 	mutex_enter(&ds->ds_lock);
-	unique = dsl_dataset_unique(ds);
-	delta = MAX(0, (int64_t)(new_reservation - unique)) -
+	ASSERT(DS_UNIQUE_IS_ACCURATE(ds));
+	unique = ds->ds_phys->ds_unique_bytes;
+	delta = MAX(0, (int64_t)(effective_value - unique)) -
 	    MAX(0, (int64_t)(ds->ds_reserved - unique));
-	ds->ds_reserved = new_reservation;
+	ds->ds_reserved = effective_value;
 	mutex_exit(&ds->ds_lock);
 
 	dsl_dir_diduse_space(ds->ds_dir, DD_USED_REFRSRV, delta, 0, 0, tx);
 	mutex_exit(&ds->ds_dir->dd_lock);
-	dsl_dir_prop_set_uint64_sync(ds->ds_dir, "refreservation",
-	    new_reservation, cr, tx);
 
-	spa_history_internal_log(LOG_DS_REFRESERV,
-	    ds->ds_dir->dd_pool->dp_spa, tx, cr, "%lld dataset = %llu",
-	    (longlong_t)new_reservation, ds->ds_object);
+	spa_history_log_internal(LOG_DS_REFRESERV,
+	    ds->ds_dir->dd_pool->dp_spa, tx, "%lld dataset = %llu",
+	    (longlong_t)effective_value, ds->ds_object);
 }
 
 int
-dsl_dataset_set_reservation(const char *dsname, uint64_t reservation)
+dsl_dataset_set_reservation(const char *dsname, zprop_source_t source,
+    uint64_t reservation)
 {
 	dsl_dataset_t *ds;
+	dsl_prop_setarg_t psa;
 	int err;
 
+	dsl_prop_setarg_init_uint64(&psa, "refreservation", source,
+	    &reservation);
+
 	err = dsl_dataset_hold(dsname, FTAG, &ds);
 	if (err)
 		return (err);
 
 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
 	    dsl_dataset_set_reservation_check,
-	    dsl_dataset_set_reservation_sync, ds, &reservation, 0);
+	    dsl_dataset_set_reservation_sync, ds, &psa, 0);
+
 	dsl_dataset_rele(ds, FTAG);
 	return (err);
 }
 
+struct dsl_ds_holdarg {
+	dsl_sync_task_group_t *dstg;
+	char *htag;
+	char *snapname;
+	boolean_t recursive;
+	boolean_t gotone;
+	boolean_t temphold;
+	char failed[MAXPATHLEN];
+};
+
+/*
+ * The max length of a temporary tag prefix is the number of hex digits
+ * required to express UINT64_MAX plus one for the hyphen.
+ */
+#define	MAX_TAG_PREFIX_LEN	17
+
 static int
 dsl_dataset_user_hold_check(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
-	char *htag = arg2;
+	struct dsl_ds_holdarg *ha = arg2;
+	char *htag = ha->htag;
 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
 	int error = 0;
 
@@ -3416,9 +3442,6 @@ dsl_dataset_user_hold_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	if (!dsl_dataset_is_snapshot(ds))
 		return (EINVAL);
 
-	if (strlen(htag) >= ZAP_MAXNAMELEN)
-		return (ENAMETOOLONG);
-
 	/* tags must be unique */
 	mutex_enter(&ds->ds_lock);
 	if (ds->ds_phys->ds_userrefs_obj) {
@@ -3431,16 +3454,22 @@ dsl_dataset_user_hold_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	}
 	mutex_exit(&ds->ds_lock);
 
+	if (error == 0 && ha->temphold &&
+	    strlen(htag) + MAX_TAG_PREFIX_LEN >= MAXNAMELEN)
+		error = E2BIG;
+
 	return (error);
 }
 
 static void
-dsl_dataset_user_hold_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_user_hold_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dataset_t *ds = arg1;
-	char *htag = arg2;
-	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
-	time_t now = gethrestime_sec();
+	struct dsl_ds_holdarg *ha = arg2;
+	char *htag = ha->htag;
+	dsl_pool_t *dp = ds->ds_dir->dd_pool;
+	objset_t *mos = dp->dp_meta_objset;
+	uint64_t now = gethrestime_sec();
 	uint64_t zapobj;
 
 	mutex_enter(&ds->ds_lock);
@@ -3460,48 +3489,43 @@ dsl_dataset_user_hold_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 
 	VERIFY(0 == zap_add(mos, zapobj, htag, 8, 1, &now, tx));
 
-	spa_history_internal_log(LOG_DS_USER_HOLD,
-	    ds->ds_dir->dd_pool->dp_spa, tx, cr, "<%s> dataset = %llu",
-	    htag, ds->ds_object);
-}
+	if (ha->temphold) {
+		VERIFY(0 == dsl_pool_user_hold(dp, ds->ds_object,
+		    htag, &now, tx));
+	}
 
-struct dsl_ds_holdarg {
-	dsl_sync_task_group_t *dstg;
-	char *htag;
-	char *snapname;
-	boolean_t recursive;
-	char failed[MAXPATHLEN];
-};
+	spa_history_log_internal(LOG_DS_USER_HOLD,
+	    dp->dp_spa, tx, "<%s> temp = %d dataset = %llu", htag,
+	    (int)ha->temphold, ds->ds_object);
+}
 
 static int
-dsl_dataset_user_hold_one(char *dsname, void *arg)
+dsl_dataset_user_hold_one(const char *dsname, void *arg)
 {
 	struct dsl_ds_holdarg *ha = arg;
 	dsl_dataset_t *ds;
 	int error;
 	char *name;
-	size_t buflen;
 
 	/* alloc a buffer to hold dsname@snapname plus terminating NULL */
-	buflen = strlen(dsname) + strlen(ha->snapname) + 2;
-	name = kmem_alloc(buflen, KM_SLEEP);
-	(void) snprintf(name, buflen, "%s@%s", dsname, ha->snapname);
+	name = kmem_asprintf("%s@%s", dsname, ha->snapname);
 	error = dsl_dataset_hold(name, ha->dstg, &ds);
-	kmem_free(name, buflen);
+	strfree(name);
 	if (error == 0) {
+		ha->gotone = B_TRUE;
 		dsl_sync_task_create(ha->dstg, dsl_dataset_user_hold_check,
-		    dsl_dataset_user_hold_sync, ds, ha->htag, 0);
+		    dsl_dataset_user_hold_sync, ds, ha, 0);
 	} else if (error == ENOENT && ha->recursive) {
 		error = 0;
 	} else {
-		(void) strcpy(ha->failed, dsname);
+		(void) strlcpy(ha->failed, dsname, sizeof (ha->failed));
 	}
 	return (error);
 }
 
 int
 dsl_dataset_user_hold(char *dsname, char *snapname, char *htag,
-    boolean_t recursive)
+    boolean_t recursive, boolean_t temphold)
 {
 	struct dsl_ds_holdarg *ha;
 	dsl_sync_task_t *dst;
@@ -3522,6 +3546,7 @@ dsl_dataset_user_hold(char *dsname, char *snapname, char *htag,
 	ha->htag = htag;
 	ha->snapname = snapname;
 	ha->recursive = recursive;
+	ha->temphold = temphold;
 	if (recursive) {
 		error = dmu_objset_find(dsname, dsl_dataset_user_hold_one,
 		    ha, DS_FIND_CHILDREN);
@@ -3542,8 +3567,11 @@ dsl_dataset_user_hold(char *dsname, char *snapname, char *htag,
 		dsl_dataset_rele(ds, ha->dstg);
 	}
 
+	if (error == 0 && recursive && !ha->gotone)
+		error = ENOENT;
+
 	if (error)
-		(void) strcpy(dsname, ha->failed);
+		(void) strlcpy(dsname, ha->failed, sizeof (ha->failed));
 
 	dsl_sync_task_group_destroy(ha->dstg);
 	kmem_free(ha, sizeof (struct dsl_ds_holdarg));
@@ -3618,10 +3646,6 @@ dsl_dataset_user_release_check(void *arg1, void *tag, dmu_tx_t *tx)
 			 */
 			if (!ra->own)
 				return (EBUSY);
-			if (ds->ds_user_ptr) {
-				ds->ds_user_evict_func(ds, ds->ds_user_ptr);
-				ds->ds_user_ptr = NULL;
-			}
 		}
 		dsda.ds = ds;
 		dsda.releasing = B_TRUE;
@@ -3632,20 +3656,28 @@ dsl_dataset_user_release_check(void *arg1, void *tag, dmu_tx_t *tx)
 }
 
 static void
-dsl_dataset_user_release_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
+dsl_dataset_user_release_sync(void *arg1, void *tag, dmu_tx_t *tx)
 {
 	struct dsl_ds_releasearg *ra = arg1;
 	dsl_dataset_t *ds = ra->ds;
-	spa_t *spa = ds->ds_dir->dd_pool->dp_spa;
-	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
+	dsl_pool_t *dp = ds->ds_dir->dd_pool;
+	objset_t *mos = dp->dp_meta_objset;
 	uint64_t zapobj;
 	uint64_t dsobj = ds->ds_object;
 	uint64_t refs;
+	int error;
+
+	if (ds->ds_objset) {
+		dmu_objset_evict(ds->ds_objset);
+		ds->ds_objset = NULL;
+	}
 
 	mutex_enter(&ds->ds_lock);
 	ds->ds_userrefs--;
 	refs = ds->ds_userrefs;
 	mutex_exit(&ds->ds_lock);
+	error = dsl_pool_user_release(dp, ds->ds_object, ra->htag, tx);
+	VERIFY(error == 0 || error == ENOENT);
 	zapobj = ds->ds_phys->ds_userrefs_obj;
 	VERIFY(0 == zap_remove(mos, zapobj, ra->htag, tx));
 	if (ds->ds_userrefs == 0 && ds->ds_phys->ds_num_children == 1 &&
@@ -3656,16 +3688,16 @@ dsl_dataset_user_release_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
 		dsda.ds = ds;
 		dsda.releasing = B_TRUE;
 		/* We already did the destroy_check */
-		dsl_dataset_destroy_sync(&dsda, tag, cr, tx);
+		dsl_dataset_destroy_sync(&dsda, tag, tx);
 	}
 
-	spa_history_internal_log(LOG_DS_USER_RELEASE,
-	    spa, tx, cr, "<%s> %lld dataset = %llu",
+	spa_history_log_internal(LOG_DS_USER_RELEASE,
+	    dp->dp_spa, tx, "<%s> %lld dataset = %llu",
 	    ra->htag, (longlong_t)refs, dsobj);
 }
 
 static int
-dsl_dataset_user_release_one(char *dsname, void *arg)
+dsl_dataset_user_release_one(const char *dsname, void *arg)
 {
 	struct dsl_ds_holdarg *ha = arg;
 	struct dsl_ds_releasearg *ra;
@@ -3673,25 +3705,21 @@ dsl_dataset_user_release_one(char *dsname, void *arg)
 	int error;
 	void *dtag = ha->dstg;
 	char *name;
-	size_t buflen;
 	boolean_t own = B_FALSE;
 	boolean_t might_destroy;
 
-	if (strlen(ha->htag) >= ZAP_MAXNAMELEN)
-		return (ENAMETOOLONG);
-
 	/* alloc a buffer to hold dsname@snapname, plus the terminating NULL */
-	buflen = strlen(dsname) + strlen(ha->snapname) + 2;
-	name = kmem_alloc(buflen, KM_SLEEP);
-	(void) snprintf(name, buflen, "%s@%s", dsname, ha->snapname);
+	name = kmem_asprintf("%s@%s", dsname, ha->snapname);
 	error = dsl_dataset_hold(name, dtag, &ds);
-	kmem_free(name, buflen);
+	strfree(name);
 	if (error == ENOENT && ha->recursive)
 		return (0);
-	(void) strcpy(ha->failed, dsname);
+	(void) strlcpy(ha->failed, dsname, sizeof (ha->failed));
 	if (error)
 		return (error);
 
+	ha->gotone = B_TRUE;
+
 	ASSERT(dsl_dataset_is_snapshot(ds));
 
 	error = dsl_dataset_release_might_destroy(ds, ha->htag, &might_destroy);
@@ -3702,19 +3730,15 @@ dsl_dataset_user_release_one(char *dsname, void *arg)
 
 	if (might_destroy) {
 #ifdef _KERNEL
+		name = kmem_asprintf("%s@%s", dsname, ha->snapname);
 		error = zfs_unmount_snap(name, NULL);
-		if (error) {
-			dsl_dataset_rele(ds, dtag);
-			return (error);
-		}
-		error = dsl_dataset_zvol_cleanup(ds, name);
+		strfree(name);
 		if (error) {
 			dsl_dataset_rele(ds, dtag);
 			return (error);
 		}
 #endif
-		if (!dsl_dataset_tryown(ds,
-		    DS_MODE_READONLY | DS_MODE_INCONSISTENT, dtag)) {
+		if (!dsl_dataset_tryown(ds, B_TRUE, dtag)) {
 			dsl_dataset_rele(ds, dtag);
 			return (EBUSY);
 		} else {
@@ -3742,6 +3766,7 @@ dsl_dataset_user_release(char *dsname, char *snapname, char *htag,
 	spa_t *spa;
 	int error;
 
+top:
 	ha = kmem_zalloc(sizeof (struct dsl_ds_holdarg), KM_SLEEP);
 
 	(void) strlcpy(ha->failed, dsname, sizeof (ha->failed));
@@ -3781,15 +3806,58 @@ dsl_dataset_user_release(char *dsname, char *snapname, char *htag,
 		kmem_free(ra, sizeof (struct dsl_ds_releasearg));
 	}
 
-	if (error)
-		(void) strcpy(dsname, ha->failed);
+	if (error == 0 && recursive && !ha->gotone)
+		error = ENOENT;
+
+	if (error && error != EBUSY)
+		(void) strlcpy(dsname, ha->failed, sizeof (ha->failed));
 
 	dsl_sync_task_group_destroy(ha->dstg);
 	kmem_free(ha, sizeof (struct dsl_ds_holdarg));
 	spa_close(spa, FTAG);
+
+	/*
+	 * We can get EBUSY if we were racing with deferred destroy and
+	 * dsl_dataset_user_release_check() hadn't done the necessary
+	 * open context setup.  We can also get EBUSY if we're racing
+	 * with destroy and that thread is the ds_owner.  Either way
+	 * the busy condition should be transient, and we should retry
+	 * the release operation.
+	 */
+	if (error == EBUSY)
+		goto top;
+
 	return (error);
 }
 
+/*
+ * Called at spa_load time to release a stale temporary user hold.
+ */
+int
+dsl_dataset_user_release_tmp(dsl_pool_t *dp, uint64_t dsobj, char *htag)
+{
+	dsl_dataset_t *ds;
+	char *snap;
+	char *name;
+	int namelen;
+	int error;
+
+	rw_enter(&dp->dp_config_rwlock, RW_READER);
+	error = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
+	rw_exit(&dp->dp_config_rwlock);
+	if (error)
+		return (error);
+	namelen = dsl_dataset_namelen(ds)+1;
+	name = kmem_alloc(namelen, KM_SLEEP);
+	dsl_dataset_name(ds, name);
+	dsl_dataset_rele(ds, FTAG);
+
+	snap = strchr(name, '@');
+	*snap = '\0';
+	++snap;
+	return (dsl_dataset_user_release(name, snap, htag, B_FALSE));
+}
+
 int
 dsl_dataset_get_holds(const char *dsname, nvlist_t **nvp)
 {
@@ -3819,3 +3887,24 @@ dsl_dataset_get_holds(const char *dsname, nvlist_t **nvp)
 	dsl_dataset_rele(ds, FTAG);
 	return (0);
 }
+
+/*
+ * Note, this fuction is used as the callback for dmu_objset_find().  We
+ * always return 0 so that we will continue to find and process
+ * inconsistent datasets, even if we encounter an error trying to
+ * process one of them.
+ */
+/* ARGSUSED */
+int
+dsl_destroy_inconsistent(const char *dsname, void *arg)
+{
+	dsl_dataset_t *ds;
+
+	if (dsl_dataset_own(dsname, B_TRUE, FTAG, &ds) == 0) {
+		if (DS_IS_INCONSISTENT(ds))
+			(void) dsl_dataset_destroy(ds, FTAG, B_FALSE);
+		else
+			dsl_dataset_disown(ds, FTAG);
+	}
+	return (0);
+}