diff --git a/cddl/contrib/opensolaris/cmd/ztest/ztest.c b/cddl/contrib/opensolaris/cmd/ztest/ztest.c
index db373e1c7ec6..1f83eee781cd 100644
--- a/cddl/contrib/opensolaris/cmd/ztest/ztest.c
+++ b/cddl/contrib/opensolaris/cmd/ztest/ztest.c
@@ -364,7 +364,7 @@ ztest_info_t ztest_info[] = {
 	{ ztest_spa_rename,			1,	&zopt_rarely	},
 	{ ztest_scrub,				1,	&zopt_rarely	},
 	{ ztest_dsl_dataset_promote_busy,	1,	&zopt_rarely	},
-	{ ztest_vdev_attach_detach,		1,	&zopt_rarely },
+	{ ztest_vdev_attach_detach,		1,	&zopt_rarely	},
 	{ ztest_vdev_LUN_growth,		1,	&zopt_rarely	},
 	{ ztest_vdev_add_remove,		1,
 	    &ztest_opts.zo_vdevtime				},
@@ -415,6 +415,13 @@ static spa_t *ztest_spa = NULL;
 static ztest_ds_t *ztest_ds;
 
 static mutex_t ztest_vdev_lock;
+
+/*
+ * The ztest_name_lock protects the pool and dataset namespace used by
+ * the individual tests. To modify the namespace, consumers must grab
+ * this lock as writer. Grabbing the lock as reader will ensure that the
+ * namespace does not change while the lock is held.
+ */
 static rwlock_t ztest_name_lock;
 
 static boolean_t ztest_dump_core = B_TRUE;
@@ -2225,6 +2232,7 @@ ztest_zil_remount(ztest_ds_t *zd, uint64_t id)
 {
 	objset_t *os = zd->zd_os;
 
+	VERIFY(mutex_lock(&zd->zd_dirobj_lock) == 0);
 	(void) rw_wrlock(&zd->zd_zilog_lock);
 
 	/* zfsvfs_teardown() */
@@ -2235,6 +2243,7 @@ ztest_zil_remount(ztest_ds_t *zd, uint64_t id)
 	zil_replay(os, zd, ztest_replay_vector);
 
 	(void) rw_unlock(&zd->zd_zilog_lock);
+	VERIFY(mutex_unlock(&zd->zd_dirobj_lock) == 0);
 }
 
 /*
@@ -4860,10 +4869,16 @@ ztest_reguid(ztest_ds_t *zd, uint64_t id)
 {
 	spa_t *spa = ztest_spa;
 	uint64_t orig, load;
+	int error;
 
 	orig = spa_guid(spa);
 	load = spa_load_guid(spa);
-	if (spa_change_guid(spa) != 0)
+
+	(void) rw_wrlock(&ztest_name_lock);
+	error = spa_change_guid(spa);
+	(void) rw_unlock(&ztest_name_lock);
+
+	if (error != 0)
 		return;
 
 	if (ztest_opts.zo_verbose >= 3) {
@@ -5540,8 +5555,15 @@ ztest_freeze(void)
 	 */
 	kernel_init(FREAD | FWRITE);
 	VERIFY3U(0, ==, spa_open(ztest_opts.zo_pool, &spa, FTAG));
+	ASSERT(spa_freeze_txg(spa) == UINT64_MAX);
 	VERIFY3U(0, ==, ztest_dataset_open(0));
 	ztest_dataset_close(0);
+
+	spa->spa_debug = B_TRUE;
+	ztest_spa = spa;
+	txg_wait_synced(spa_get_dsl(spa), 0);
+	ztest_reguid(NULL, 0);
+
 	spa_close(spa, FTAG);
 	kernel_fini();
 }
diff --git a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_import.c b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_import.c
index 7e73d0f9b688..7e39b0b78f2b 100644
--- a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_import.c
+++ b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_import.c
@@ -21,7 +21,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
- * Copyright (c) 2011 by Delphix. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /*
@@ -437,8 +437,8 @@ get_configs(libzfs_handle_t *hdl, pool_list_t *pl, boolean_t active_ok)
 	uint_t i, nspares, nl2cache;
 	boolean_t config_seen;
 	uint64_t best_txg;
-	char *name, *hostname, *comment;
-	uint64_t version, guid;
+	char *name, *hostname;
+	uint64_t guid;
 	uint_t children = 0;
 	nvlist_t **child = NULL;
 	uint_t holes;
@@ -524,61 +524,54 @@ get_configs(libzfs_handle_t *hdl, pool_list_t *pl, boolean_t active_ok)
 				 * configuration:
 				 *
 				 *	version
-				 * 	pool guid
-				 * 	name
+				 *	pool guid
+				 *	name
+				 *	pool txg (if available)
 				 *	comment (if available)
-				 * 	pool state
+				 *	pool state
 				 *	hostid (if available)
 				 *	hostname (if available)
 				 */
-				uint64_t state;
+				uint64_t state, version, pool_txg;
+				char *comment = NULL;
 
-				verify(nvlist_lookup_uint64(tmp,
-				    ZPOOL_CONFIG_VERSION, &version) == 0);
-				if (nvlist_add_uint64(config,
-				    ZPOOL_CONFIG_VERSION, version) != 0)
-					goto nomem;
-				verify(nvlist_lookup_uint64(tmp,
-				    ZPOOL_CONFIG_POOL_GUID, &guid) == 0);
-				if (nvlist_add_uint64(config,
-				    ZPOOL_CONFIG_POOL_GUID, guid) != 0)
-					goto nomem;
-				verify(nvlist_lookup_string(tmp,
-				    ZPOOL_CONFIG_POOL_NAME, &name) == 0);
-				if (nvlist_add_string(config,
-				    ZPOOL_CONFIG_POOL_NAME, name) != 0)
-					goto nomem;
+				version = fnvlist_lookup_uint64(tmp,
+				    ZPOOL_CONFIG_VERSION);
+				fnvlist_add_uint64(config,
+				    ZPOOL_CONFIG_VERSION, version);
+				guid = fnvlist_lookup_uint64(tmp,
+				    ZPOOL_CONFIG_POOL_GUID);
+				fnvlist_add_uint64(config,
+				    ZPOOL_CONFIG_POOL_GUID, guid);
+				name = fnvlist_lookup_string(tmp,
+				    ZPOOL_CONFIG_POOL_NAME);
+				fnvlist_add_string(config,
+				    ZPOOL_CONFIG_POOL_NAME, name);
+
+				if (nvlist_lookup_uint64(tmp,
+				    ZPOOL_CONFIG_POOL_TXG, &pool_txg) == 0)
+					fnvlist_add_uint64(config,
+					    ZPOOL_CONFIG_POOL_TXG, pool_txg);
 
-				/*
-				 * COMMENT is optional, don't bail if it's not
-				 * there, instead, set it to NULL.
-				 */
 				if (nvlist_lookup_string(tmp,
-				    ZPOOL_CONFIG_COMMENT, &comment) != 0)
-					comment = NULL;
-				else if (nvlist_add_string(config,
-				    ZPOOL_CONFIG_COMMENT, comment) != 0)
-					goto nomem;
+				    ZPOOL_CONFIG_COMMENT, &comment) == 0)
+					fnvlist_add_string(config,
+					    ZPOOL_CONFIG_COMMENT, comment);
 
-				verify(nvlist_lookup_uint64(tmp,
-				    ZPOOL_CONFIG_POOL_STATE, &state) == 0);
-				if (nvlist_add_uint64(config,
-				    ZPOOL_CONFIG_POOL_STATE, state) != 0)
-					goto nomem;
+				state = fnvlist_lookup_uint64(tmp,
+				    ZPOOL_CONFIG_POOL_STATE);
+				fnvlist_add_uint64(config,
+				    ZPOOL_CONFIG_POOL_STATE, state);
 
 				hostid = 0;
 				if (nvlist_lookup_uint64(tmp,
 				    ZPOOL_CONFIG_HOSTID, &hostid) == 0) {
-					if (nvlist_add_uint64(config,
-					    ZPOOL_CONFIG_HOSTID, hostid) != 0)
-						goto nomem;
-					verify(nvlist_lookup_string(tmp,
-					    ZPOOL_CONFIG_HOSTNAME,
-					    &hostname) == 0);
-					if (nvlist_add_string(config,
-					    ZPOOL_CONFIG_HOSTNAME,
-					    hostname) != 0)
-						goto nomem;
+					fnvlist_add_uint64(config,
+					    ZPOOL_CONFIG_HOSTID, hostid);
+					hostname = fnvlist_lookup_string(tmp,
+					    ZPOOL_CONFIG_HOSTNAME);
+					fnvlist_add_string(config,
+					    ZPOOL_CONFIG_HOSTNAME, hostname);
 				}
 
 				config_seen = B_TRUE;
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
index 2204e9d8bac4..a4c63f36e3c8 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
@@ -1769,15 +1769,15 @@ dmu_init(void)
 	dnode_init();
 	dbuf_init();
 	zfetch_init();
-	arc_init();
 	l2arc_init();
+	arc_init();
 }
 
 void
 dmu_fini(void)
 {
-	l2arc_fini();
 	arc_fini();
+	l2arc_fini();
 	zfetch_fini();
 	dbuf_fini();
 	dnode_fini();
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c
index 0b8cc6267b8a..7f554e553f81 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c
@@ -1649,13 +1649,6 @@ dmu_recv_existing_end(dmu_recv_cookie_t *drc)
 	dsl_dataset_t *ds = drc->drc_logical_ds;
 	int err, myerr;
 
-	/*
-	 * XXX hack; seems the ds is still dirty and dsl_pool_zil_clean()
-	 * expects it to have a ds_user_ptr (and zil), but clone_swap()
-	 * can close it.
-	 */
-	txg_wait_synced(ds->ds_dir->dd_pool, 0);
-
 	if (dsl_dataset_tryown(ds, FALSE, dmu_recv_tag)) {
 		err = dsl_dataset_clone_swap(drc->drc_real_ds, ds,
 		    drc->drc_force);
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c
index 4aad2c91aaba..49bf9fa40d6b 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c
@@ -106,14 +106,8 @@ dsl_dataset_block_born(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx)
 	ASSERT(BP_GET_TYPE(bp) != DMU_OT_NONE);
 	ASSERT(DMU_OT_IS_VALID(BP_GET_TYPE(bp)));
 	if (ds == NULL) {
-		/*
-		 * Account for the meta-objset space in its placeholder
-		 * dsl_dir.
-		 */
-		ASSERT3U(compressed, ==, uncompressed); /* it's all metadata */
-		dsl_dir_diduse_space(tx->tx_pool->dp_mos_dir, DD_USED_HEAD,
-		    used, compressed, uncompressed, tx);
-		dsl_dir_dirty(tx->tx_pool->dp_mos_dir, tx);
+		dsl_pool_mos_diduse_space(tx->tx_pool,
+		    used, compressed, uncompressed);
 		return;
 	}
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
@@ -149,15 +143,9 @@ dsl_dataset_block_kill(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx,
 
 	ASSERT(used > 0);
 	if (ds == NULL) {
-		/*
-		 * Account for the meta-objset space in its placeholder
-		 * dataset.
-		 */
 		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);
-		dsl_dir_dirty(tx->tx_pool->dp_mos_dir, tx);
+		dsl_pool_mos_diduse_space(tx->tx_pool,
+		    -used, -compressed, -uncompressed);
 		return (used);
 	}
 	ASSERT3P(tx->tx_pool, ==, ds->ds_dir->dd_pool);
@@ -1116,26 +1104,26 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 	dummy_ds.ds_dir = dd;
 	dummy_ds.ds_object = ds->ds_object;
 
-	/*
-	 * Check for errors and mark this ds as inconsistent, in
-	 * case we crash while freeing the objects.
-	 */
-	err = dsl_sync_task_do(dd->dd_pool, dsl_dataset_destroy_begin_check,
-	    dsl_dataset_destroy_begin_sync, ds, NULL, 0);
-	if (err)
-		goto out;
-
-	err = dmu_objset_from_ds(ds, &os);
-	if (err)
-		goto out;
-
-	/*
-	 * If async destruction is not enabled try to remove all objects
-	 * while in the open context so that there is less work to do in
-	 * the syncing context.
-	 */
 	if (!spa_feature_is_enabled(dsl_dataset_get_spa(ds),
 	    &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) {
+		/*
+		 * Check for errors and mark this ds as inconsistent, in
+		 * case we crash while freeing the objects.
+		 */
+		err = dsl_sync_task_do(dd->dd_pool,
+		    dsl_dataset_destroy_begin_check,
+		    dsl_dataset_destroy_begin_sync, ds, NULL, 0);
+		if (err)
+			goto out;
+
+		err = dmu_objset_from_ds(ds, &os);
+		if (err)
+			goto out;
+
+		/*
+		 * Remove all objects while in the open context so that
+		 * there is less work to do in the syncing context.
+		 */
 		for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE,
 		    ds->ds_phys->ds_prev_snap_txg)) {
 			/*
@@ -1146,30 +1134,25 @@ dsl_dataset_destroy(dsl_dataset_t *ds, void *tag, boolean_t defer)
 		}
 		if (err != ESRCH)
 			goto out;
-	}
 
-	/*
-	 * Only the ZIL knows how to free log blocks.
-	 */
-	zil_destroy(dmu_objset_zil(os), B_FALSE);
+		/*
+		 * Sync out all in-flight IO.
+		 */
+		txg_wait_synced(dd->dd_pool, 0);
 
-	/*
-	 * Sync out all in-flight IO.
-	 */
-	txg_wait_synced(dd->dd_pool, 0);
+		/*
+		 * If we managed to free all the objects in open
+		 * context, the user space accounting should be zero.
+		 */
+		if (ds->ds_phys->ds_bp.blk_fill == 0 &&
+		    dmu_objset_userused_enabled(os)) {
+			uint64_t count;
 
-	/*
-	 * If we managed to free all the objects in open
-	 * context, the user space accounting should be zero.
-	 */
-	if (ds->ds_phys->ds_bp.blk_fill == 0 &&
-	    dmu_objset_userused_enabled(os)) {
-		uint64_t count;
-
-		ASSERT(zap_count(os, DMU_USERUSED_OBJECT, &count) != 0 ||
-		    count == 0);
-		ASSERT(zap_count(os, DMU_GROUPUSED_OBJECT, &count) != 0 ||
-		    count == 0);
+			ASSERT(zap_count(os, DMU_USERUSED_OBJECT,
+			    &count) != 0 || count == 0);
+			ASSERT(zap_count(os, DMU_GROUPUSED_OBJECT,
+			    &count) != 0 || count == 0);
+		}
 	}
 
 	rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
@@ -1906,6 +1889,7 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 	} else {
 		zfeature_info_t *async_destroy =
 		    &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY];
+		objset_t *os;
 
 		/*
 		 * There's no next snapshot, so this is a head dataset.
@@ -1917,6 +1901,8 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 		dsl_deadlist_free(mos, ds->ds_phys->ds_deadlist_obj, tx);
 		ds->ds_phys->ds_deadlist_obj = 0;
 
+		VERIFY3U(0, ==, dmu_objset_from_ds(ds, &os));
+
 		if (!spa_feature_is_enabled(dp->dp_spa, async_destroy)) {
 			err = old_synchronous_dataset_destroy(ds, tx);
 		} else {
@@ -1926,12 +1912,12 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 			 */
 			uint64_t used, comp, uncomp;
 
-			ASSERT(err == 0 || err == EBUSY);
+			zil_destroy_sync(dmu_objset_zil(os), tx);
+
 			if (!spa_feature_is_active(dp->dp_spa, async_destroy)) {
 				spa_feature_incr(dp->dp_spa, async_destroy, tx);
-				dp->dp_bptree_obj = bptree_alloc(
-				    dp->dp_meta_objset, tx);
-				VERIFY(zap_add(dp->dp_meta_objset,
+				dp->dp_bptree_obj = bptree_alloc(mos, tx);
+				VERIFY(zap_add(mos,
 				    DMU_POOL_DIRECTORY_OBJECT,
 				    DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
 				    &dp->dp_bptree_obj, tx) == 0);
@@ -1944,7 +1930,7 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 			ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) ||
 			    ds->ds_phys->ds_unique_bytes == used);
 
-			bptree_add(dp->dp_meta_objset, dp->dp_bptree_obj,
+			bptree_add(mos, dp->dp_bptree_obj,
 			    &ds->ds_phys->ds_bp, ds->ds_phys->ds_prev_snap_txg,
 			    used, comp, uncomp, tx);
 			dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD,
@@ -2233,7 +2219,6 @@ dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
 	ds->ds_phys->ds_fsid_guid = ds->ds_fsid_guid;
 
-	dsl_dir_dirty(ds->ds_dir, tx);
 	dmu_objset_sync(ds->ds_objset, zio, tx);
 }
 
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c
index 1213445da81b..8472f465ec4e 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c
@@ -195,7 +195,6 @@ errout:
 	kmem_free(dd, sizeof (dsl_dir_t));
 	dmu_buf_rele(dbuf, tag);
 	return (err);
-
 }
 
 void
@@ -229,7 +228,7 @@ dsl_dir_name(dsl_dir_t *dd, char *buf)
 	}
 }
 
-/* Calculate name legnth, avoiding all the strcat calls of dsl_dir_name */
+/* Calculate name length, avoiding all the strcat calls of dsl_dir_name */
 int
 dsl_dir_namelen(dsl_dir_t *dd)
 {
@@ -593,8 +592,6 @@ dsl_dir_sync(dsl_dir_t *dd, dmu_tx_t *tx)
 {
 	ASSERT(dmu_tx_is_syncing(tx));
 
-	dmu_buf_will_dirty(dd->dd_dbuf, tx);
-
 	mutex_enter(&dd->dd_lock);
 	ASSERT3U(dd->dd_tempreserved[tx->tx_txg&TXG_MASK], ==, 0);
 	dprintf_dd(dd, "txg=%llu towrite=%lluK\n", tx->tx_txg,
@@ -951,8 +948,6 @@ dsl_dir_diduse_space(dsl_dir_t *dd, dd_used_t type,
 	ASSERT(dmu_tx_is_syncing(tx));
 	ASSERT(type < DD_USED_NUM);
 
-	dsl_dir_dirty(dd, tx);
-
 	if (needlock)
 		mutex_enter(&dd->dd_lock);
 	accounted_delta = parent_delta(dd, dd->dd_phys->dd_used_bytes, used);
@@ -961,6 +956,7 @@ dsl_dir_diduse_space(dsl_dir_t *dd, dd_used_t type,
 	    dd->dd_phys->dd_compressed_bytes >= -compressed);
 	ASSERT(uncompressed >= 0 ||
 	    dd->dd_phys->dd_uncompressed_bytes >= -uncompressed);
+	dmu_buf_will_dirty(dd->dd_dbuf, tx);
 	dd->dd_phys->dd_used_bytes += used;
 	dd->dd_phys->dd_uncompressed_bytes += uncompressed;
 	dd->dd_phys->dd_compressed_bytes += compressed;
@@ -1002,13 +998,13 @@ dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
 	if (delta == 0 || !(dd->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN))
 		return;
 
-	dsl_dir_dirty(dd, tx);
 	if (needlock)
 		mutex_enter(&dd->dd_lock);
 	ASSERT(delta > 0 ?
 	    dd->dd_phys->dd_used_breakdown[oldtype] >= delta :
 	    dd->dd_phys->dd_used_breakdown[newtype] >= -delta);
 	ASSERT(dd->dd_phys->dd_used_bytes >= ABS(delta));
+	dmu_buf_will_dirty(dd->dd_dbuf, tx);
 	dd->dd_phys->dd_used_breakdown[oldtype] -= delta;
 	dd->dd_phys->dd_used_breakdown[newtype] += delta;
 	if (needlock)
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c
index d698e594e2ff..97065096c990 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c
@@ -42,6 +42,7 @@
 #include <sys/dsl_deadlist.h>
 #include <sys/bptree.h>
 #include <sys/zfeature.h>
+#include <sys/zil_impl.h>
 
 int zfs_no_write_throttle = 0;
 int zfs_write_limit_shift = 3;			/* 1/8th of physical memory */
@@ -111,12 +112,12 @@ dsl_pool_open_impl(spa_t *spa, uint64_t txg)
 
 	txg_list_create(&dp->dp_dirty_datasets,
 	    offsetof(dsl_dataset_t, ds_dirty_link));
+	txg_list_create(&dp->dp_dirty_zilogs,
+	    offsetof(zilog_t, zl_dirty_link));
 	txg_list_create(&dp->dp_dirty_dirs,
 	    offsetof(dsl_dir_t, dd_dirty_link));
 	txg_list_create(&dp->dp_sync_tasks,
 	    offsetof(dsl_sync_task_group_t, dstg_node));
-	list_create(&dp->dp_synced_datasets, sizeof (dsl_dataset_t),
-	    offsetof(dsl_dataset_t, ds_synced_link));
 
 	mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
 
@@ -249,9 +250,9 @@ dsl_pool_close(dsl_pool_t *dp)
 		dmu_objset_evict(dp->dp_meta_objset);
 
 	txg_list_destroy(&dp->dp_dirty_datasets);
+	txg_list_destroy(&dp->dp_dirty_zilogs);
 	txg_list_destroy(&dp->dp_sync_tasks);
 	txg_list_destroy(&dp->dp_dirty_dirs);
-	list_destroy(&dp->dp_synced_datasets);
 
 	arc_flush(dp->dp_spa);
 	txg_fini(dp);
@@ -331,6 +332,21 @@ dsl_pool_create(spa_t *spa, nvlist_t *zplprops, uint64_t txg)
 	return (dp);
 }
 
+/*
+ * Account for the meta-objset space in its placeholder dsl_dir.
+ */
+void
+dsl_pool_mos_diduse_space(dsl_pool_t *dp,
+    int64_t used, int64_t comp, int64_t uncomp)
+{
+	ASSERT3U(comp, ==, uncomp); /* it's all metadata */
+	mutex_enter(&dp->dp_lock);
+	dp->dp_mos_used_delta += used;
+	dp->dp_mos_compressed_delta += comp;
+	dp->dp_mos_uncompressed_delta += uncomp;
+	mutex_exit(&dp->dp_lock);
+}
+
 static int
 deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
 {
@@ -349,11 +365,14 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 	dmu_tx_t *tx;
 	dsl_dir_t *dd;
 	dsl_dataset_t *ds;
-	dsl_sync_task_group_t *dstg;
 	objset_t *mos = dp->dp_meta_objset;
 	hrtime_t start, write_time;
 	uint64_t data_written;
 	int err;
+	list_t synced_datasets;
+
+	list_create(&synced_datasets, sizeof (dsl_dataset_t),
+	    offsetof(dsl_dataset_t, ds_synced_link));
 
 	/*
 	 * We need to copy dp_space_towrite() before doing
@@ -376,7 +395,7 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 		 * may sync newly-created datasets on pass 2.
 		 */
 		ASSERT(!list_link_active(&ds->ds_synced_link));
-		list_insert_tail(&dp->dp_synced_datasets, ds);
+		list_insert_tail(&synced_datasets, ds);
 		dsl_dataset_sync(ds, zio, tx);
 	}
 	DTRACE_PROBE(pool_sync__1setup);
@@ -386,15 +405,20 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 	ASSERT(err == 0);
 	DTRACE_PROBE(pool_sync__2rootzio);
 
-	for (ds = list_head(&dp->dp_synced_datasets); ds;
-	    ds = list_next(&dp->dp_synced_datasets, ds))
+	/*
+	 * After the data blocks have been written (ensured by the zio_wait()
+	 * above), update the user/group space accounting.
+	 */
+	for (ds = list_head(&synced_datasets); ds;
+	    ds = list_next(&synced_datasets, ds))
 		dmu_objset_do_userquota_updates(ds->ds_objset, tx);
 
 	/*
 	 * Sync the datasets again to push out the changes due to
 	 * userspace updates.  This must be done before we process the
-	 * sync tasks, because that could cause a snapshot of a dataset
-	 * whose ds_bp will be rewritten when we do this 2nd sync.
+	 * sync tasks, so that any snapshots will have the correct
+	 * user accounting information (and we won't get confused
+	 * about which blocks are part of the snapshot).
 	 */
 	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
 	while (ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) {
@@ -405,30 +429,42 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 	err = zio_wait(zio);
 
 	/*
-	 * Move dead blocks from the pending deadlist to the on-disk
-	 * deadlist.
+	 * Now that the datasets have been completely synced, we can
+	 * clean up our in-memory structures accumulated while syncing:
+	 *
+	 *  - move dead blocks from the pending deadlist to the on-disk deadlist
+	 *  - clean up zil records
+	 *  - release hold from dsl_dataset_dirty()
 	 */
-	for (ds = list_head(&dp->dp_synced_datasets); ds;
-	    ds = list_next(&dp->dp_synced_datasets, ds)) {
+	while (ds = list_remove_head(&synced_datasets)) {
+		objset_t *os = ds->ds_objset;
 		bplist_iterate(&ds->ds_pending_deadlist,
 		    deadlist_enqueue_cb, &ds->ds_deadlist, tx);
+		ASSERT(!dmu_objset_is_dirty(os, txg));
+		dmu_buf_rele(ds->ds_dbuf, ds);
 	}
 
-	while (dstg = txg_list_remove(&dp->dp_sync_tasks, txg)) {
-		/*
-		 * No more sync tasks should have been added while we
-		 * were syncing.
-		 */
-		ASSERT(spa_sync_pass(dp->dp_spa) == 1);
-		dsl_sync_task_group_sync(dstg, tx);
-	}
-	DTRACE_PROBE(pool_sync__3task);
-
 	start = gethrtime();
 	while (dd = txg_list_remove(&dp->dp_dirty_dirs, txg))
 		dsl_dir_sync(dd, tx);
 	write_time += gethrtime() - start;
 
+	/*
+	 * The MOS's space is accounted for in the pool/$MOS
+	 * (dp_mos_dir).  We can't modify the mos while we're syncing
+	 * it, so we remember the deltas and apply them here.
+	 */
+	if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
+	    dp->dp_mos_uncompressed_delta != 0) {
+		dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
+		    dp->dp_mos_used_delta,
+		    dp->dp_mos_compressed_delta,
+		    dp->dp_mos_uncompressed_delta, tx);
+		dp->dp_mos_used_delta = 0;
+		dp->dp_mos_compressed_delta = 0;
+		dp->dp_mos_uncompressed_delta = 0;
+	}
+
 	start = gethrtime();
 	if (list_head(&mos->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
 	    list_head(&mos->os_free_dnodes[txg & TXG_MASK]) != NULL) {
@@ -444,6 +480,27 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 	    hrtime_t, dp->dp_read_overhead);
 	write_time -= dp->dp_read_overhead;
 
+	/*
+	 * If we modify a dataset in the same txg that we want to destroy it,
+	 * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
+	 * dsl_dir_destroy_check() will fail if there are unexpected holds.
+	 * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
+	 * and clearing the hold on it) before we process the sync_tasks.
+	 * The MOS data dirtied by the sync_tasks will be synced on the next
+	 * pass.
+	 */
+	DTRACE_PROBE(pool_sync__3task);
+	if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
+		dsl_sync_task_group_t *dstg;
+		/*
+		 * No more sync tasks should have been added while we
+		 * were syncing.
+		 */
+		ASSERT(spa_sync_pass(dp->dp_spa) == 1);
+		while (dstg = txg_list_remove(&dp->dp_sync_tasks, txg))
+			dsl_sync_task_group_sync(dstg, tx);
+	}
+
 	dmu_tx_commit(tx);
 
 	dp->dp_space_towrite[txg & TXG_MASK] = 0;
@@ -492,15 +549,14 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 void
 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
 {
+	zilog_t *zilog;
 	dsl_dataset_t *ds;
-	objset_t *os;
 
-	while (ds = list_head(&dp->dp_synced_datasets)) {
-		list_remove(&dp->dp_synced_datasets, ds);
-		os = ds->ds_objset;
-		zil_clean(os->os_zil, txg);
-		ASSERT(!dmu_objset_is_dirty(os, txg));
-		dmu_buf_rele(ds->ds_dbuf, ds);
+	while (zilog = txg_list_remove(&dp->dp_dirty_zilogs, txg)) {
+		ds = dmu_objset_ds(zilog->zl_os);
+		zil_clean(zilog, txg);
+		ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
+		dmu_buf_rele(ds->ds_dbuf, zilog);
 	}
 	ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
 }
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c
index 53ce61f7f0db..8aa7172ca8a0 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c
@@ -120,6 +120,8 @@ const zio_taskq_info_t zio_taskqs[ZIO_TYPES][ZIO_TASKQ_TYPES] = {
 
 static dsl_syncfunc_t spa_sync_version;
 static dsl_syncfunc_t spa_sync_props;
+static dsl_checkfunc_t spa_change_guid_check;
+static dsl_syncfunc_t spa_change_guid_sync;
 static boolean_t spa_has_active_shared_spare(spa_t *spa);
 static int spa_load_impl(spa_t *spa, uint64_t, nvlist_t *config,
     spa_load_state_t state, spa_import_type_t type, boolean_t mosconfig,
@@ -683,6 +685,56 @@ spa_prop_clear_bootfs(spa_t *spa, uint64_t dsobj, dmu_tx_t *tx)
 	}
 }
 
+/*ARGSUSED*/
+static int
+spa_change_guid_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	spa_t *spa = arg1;
+	uint64_t *newguid = arg2;
+	vdev_t *rvd = spa->spa_root_vdev;
+	uint64_t vdev_state;
+
+	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
+	vdev_state = rvd->vdev_state;
+	spa_config_exit(spa, SCL_STATE, FTAG);
+
+	if (vdev_state != VDEV_STATE_HEALTHY)
+		return (ENXIO);
+
+	ASSERT3U(spa_guid(spa), !=, *newguid);
+
+	return (0);
+}
+
+static void
+spa_change_guid_sync(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	spa_t *spa = arg1;
+	uint64_t *newguid = arg2;
+	uint64_t oldguid;
+	vdev_t *rvd = spa->spa_root_vdev;
+
+	oldguid = spa_guid(spa);
+
+	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
+	rvd->vdev_guid = *newguid;
+	rvd->vdev_guid_sum += (*newguid - oldguid);
+	vdev_config_dirty(rvd);
+	spa_config_exit(spa, SCL_STATE, FTAG);
+
+#ifdef __FreeBSD__
+	/*
+	 * TODO: until recent illumos logging changes are merged
+	 *       log reguid as pool property change
+	 */
+	spa_history_log_internal(LOG_POOL_PROPSET, spa, tx,
+	    "guid change old=%llu new=%llu", oldguid, *newguid);
+#else
+	spa_history_log_internal(spa, "guid change", tx, "old=%lld new=%lld",
+	    oldguid, *newguid);
+#endif
+}
+
 /*
  * Change the GUID for the pool.  This is done so that we can later
  * re-import a pool built from a clone of our own vdevs.  We will modify
@@ -695,29 +747,23 @@ spa_prop_clear_bootfs(spa_t *spa, uint64_t dsobj, dmu_tx_t *tx)
 int
 spa_change_guid(spa_t *spa)
 {
-	uint64_t	oldguid, newguid;
-	uint64_t	txg;
+	int error;
+	uint64_t guid;
 
-	if (!(spa_mode_global & FWRITE))
-		return (EROFS);
+	mutex_enter(&spa_namespace_lock);
+	guid = spa_generate_guid(NULL);
 
-	txg = spa_vdev_enter(spa);
+	error = dsl_sync_task_do(spa_get_dsl(spa), spa_change_guid_check,
+	    spa_change_guid_sync, spa, &guid, 5);
 
-	if (spa->spa_root_vdev->vdev_state != VDEV_STATE_HEALTHY)
-		return (spa_vdev_exit(spa, NULL, txg, ENXIO));
+	if (error == 0) {
+		spa_config_sync(spa, B_FALSE, B_TRUE);
+		spa_event_notify(spa, NULL, ESC_ZFS_POOL_REGUID);
+	}
 
-	oldguid = spa_guid(spa);
-	newguid = spa_generate_guid(NULL);
-	ASSERT3U(oldguid, !=, newguid);
+	mutex_exit(&spa_namespace_lock);
 
-	spa->spa_root_vdev->vdev_guid = newguid;
-	spa->spa_root_vdev->vdev_guid_sum += (newguid - oldguid);
-
-	vdev_config_dirty(spa->spa_root_vdev);
-
-	spa_event_notify(spa, NULL, ESC_ZFS_POOL_REGUID);
-
-	return (spa_vdev_exit(spa, NULL, txg, 0));
+	return (error);
 }
 
 /*
@@ -6107,6 +6153,9 @@ spa_sync(spa_t *spa, uint64_t txg)
 				    rvd->vdev_children, txg, B_TRUE);
 		}
 
+		if (error == 0)
+			spa->spa_last_synced_guid = rvd->vdev_guid;
+
 		spa_config_exit(spa, SCL_STATE, FTAG);
 
 		if (error == 0)
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c
index 83c3d31fe313..caf1ce0ecd5e 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c
@@ -1352,16 +1352,29 @@ spa_name(spa_t *spa)
 uint64_t
 spa_guid(spa_t *spa)
 {
+	dsl_pool_t *dp = spa_get_dsl(spa);
+	uint64_t guid;
+
 	/*
 	 * If we fail to parse the config during spa_load(), we can go through
 	 * the error path (which posts an ereport) and end up here with no root
 	 * vdev.  We stash the original pool guid in 'spa_config_guid' to handle
 	 * this case.
 	 */
-	if (spa->spa_root_vdev != NULL)
+	if (spa->spa_root_vdev == NULL)
+		return (spa->spa_config_guid);
+
+	guid = spa->spa_last_synced_guid != 0 ?
+	    spa->spa_last_synced_guid : spa->spa_root_vdev->vdev_guid;
+
+	/*
+	 * Return the most recently synced out guid unless we're
+	 * in syncing context.
+	 */
+	if (dp && dsl_pool_sync_context(dp))
 		return (spa->spa_root_vdev->vdev_guid);
 	else
-		return (spa->spa_config_guid);
+		return (guid);
 }
 
 uint64_t
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_pool.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_pool.h
index e2c12ab46d32..2da251c05e84 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_pool.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_pool.h
@@ -82,7 +82,6 @@ typedef struct dsl_pool {
 
 	/* No lock needed - sync context only */
 	blkptr_t dp_meta_rootbp;
-	list_t dp_synced_datasets;
 	hrtime_t dp_read_overhead;
 	uint64_t dp_throughput; /* bytes per millisec */
 	uint64_t dp_write_limit;
@@ -96,10 +95,14 @@ typedef struct dsl_pool {
 	kmutex_t dp_lock;
 	uint64_t dp_space_towrite[TXG_SIZE];
 	uint64_t dp_tempreserved[TXG_SIZE];
+	uint64_t dp_mos_used_delta;
+	uint64_t dp_mos_compressed_delta;
+	uint64_t dp_mos_uncompressed_delta;
 
 	/* Has its own locking */
 	tx_state_t dp_tx;
 	txg_list_t dp_dirty_datasets;
+	txg_list_t dp_dirty_zilogs;
 	txg_list_t dp_dirty_dirs;
 	txg_list_t dp_sync_tasks;
 
@@ -139,6 +142,8 @@ int dsl_read_nolock(zio_t *pio, spa_t *spa, const blkptr_t *bpp,
 void dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx);
 void dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx);
 void dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx);
+void dsl_pool_mos_diduse_space(dsl_pool_t *dp,
+    int64_t used, int64_t comp, int64_t uncomp);
 
 taskq_t *dsl_pool_vnrele_taskq(dsl_pool_t *dp);
 
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/spa_impl.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/spa_impl.h
index b4276743b11d..da31a2243ecd 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/spa_impl.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/spa_impl.h
@@ -141,6 +141,7 @@ struct spa {
 	vdev_t		*spa_root_vdev;		/* top-level vdev container */
 	uint64_t	spa_config_guid;	/* config pool guid */
 	uint64_t	spa_load_guid;		/* spa_load initialized guid */
+	uint64_t	spa_last_synced_guid;	/* last synced guid */
 	list_t		spa_config_dirty_list;	/* vdevs with dirty config */
 	list_t		spa_state_dirty_list;	/* vdevs with dirty state */
 	spa_aux_vdev_t	spa_spares;		/* hot spares */
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg.h
index e323d5efabb7..1287f09c7ee8 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg.h
@@ -22,6 +22,9 @@
  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright (c) 2012 by Delphix. All rights reserved.
+ */
 
 #ifndef _SYS_TXG_H
 #define	_SYS_TXG_H
@@ -115,7 +118,7 @@ extern boolean_t txg_sync_waiting(struct dsl_pool *dp);
 
 extern void txg_list_create(txg_list_t *tl, size_t offset);
 extern void txg_list_destroy(txg_list_t *tl);
-extern int txg_list_empty(txg_list_t *tl, uint64_t txg);
+extern boolean_t txg_list_empty(txg_list_t *tl, uint64_t txg);
 extern int txg_list_add(txg_list_t *tl, void *p, uint64_t txg);
 extern int txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg);
 extern void *txg_list_remove(txg_list_t *tl, uint64_t txg);
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/vdev.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/vdev.h
index 2329d5b85c68..7e34889b61f0 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/vdev.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/vdev.h
@@ -142,7 +142,7 @@ extern nvlist_t *vdev_config_generate(spa_t *spa, vdev_t *vd,
 struct uberblock;
 extern uint64_t vdev_label_offset(uint64_t psize, int l, uint64_t offset);
 extern int vdev_label_number(uint64_t psise, uint64_t offset);
-extern nvlist_t *vdev_label_read_config(vdev_t *vd, int label);
+extern nvlist_t *vdev_label_read_config(vdev_t *vd, uint64_t txg);
 extern void vdev_uberblock_load(vdev_t *, struct uberblock *, nvlist_t **);
 
 typedef enum {
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h
index a4c5575b2dba..e52c65bb762f 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -395,6 +396,7 @@ extern void	zil_replay(objset_t *os, void *arg,
     zil_replay_func_t *replay_func[TX_MAX_TYPE]);
 extern boolean_t zil_replaying(zilog_t *zilog, dmu_tx_t *tx);
 extern void	zil_destroy(zilog_t *zilog, boolean_t keep_first);
+extern void	zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx);
 extern void	zil_rollback_destroy(zilog_t *zilog, dmu_tx_t *tx);
 
 extern itx_t	*zil_itx_create(uint64_t txtype, size_t lrsize);
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil_impl.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil_impl.h
index 1d4c0cc6c1de..58566203b697 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil_impl.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil_impl.h
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -130,6 +131,7 @@ struct zilog {
 	zil_header_t	zl_old_header;	/* debugging aid */
 	uint_t		zl_prev_blks[ZIL_PREV_BLKS]; /* size - sector rounded */
 	uint_t		zl_prev_rotor;	/* rotor for zl_prev[] */
+	txg_node_t	zl_dirty_link;	/* protected by dp_dirty_zilogs list */
 };
 
 typedef struct zil_bp_node {
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/txg.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/txg.c
index 2e35e9eb491c..dac619bea071 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/txg.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/txg.c
@@ -21,6 +21,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Portions Copyright 2011 Martin Matuska <mm@FreeBSD.org>
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -596,7 +597,7 @@ txg_list_destroy(txg_list_t *tl)
 	mutex_destroy(&tl->tl_lock);
 }
 
-int
+boolean_t
 txg_list_empty(txg_list_t *tl, uint64_t txg)
 {
 	return (tl->tl_head[txg & TXG_MASK] == NULL);
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
index 950f2f17be41..b07469a4d5ca 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
@@ -1328,9 +1328,9 @@ vdev_validate(vdev_t *vd, boolean_t strict)
 	if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
 		uint64_t aux_guid = 0;
 		nvlist_t *nvl;
+		uint64_t txg = strict ? spa->spa_config_txg : -1ULL;
 
-		if ((label = vdev_label_read_config(vd, VDEV_BEST_LABEL)) ==
-		    NULL) {
+		if ((label = vdev_label_read_config(vd, txg)) == NULL) {
 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
 			    VDEV_AUX_BAD_LABEL);
 			return (0);
@@ -1512,7 +1512,7 @@ vdev_reopen(vdev_t *vd)
 		    !l2arc_vdev_present(vd))
 			l2arc_add_vdev(spa, vd);
 	} else {
-		(void) vdev_validate(vd, B_TRUE);
+		(void) vdev_validate(vd, spa_last_synced_txg(spa));
 	}
 
 	/*
@@ -1971,7 +1971,7 @@ vdev_validate_aux(vdev_t *vd)
 	if (!vdev_readable(vd))
 		return (0);
 
-	if ((label = vdev_label_read_config(vd, VDEV_BEST_LABEL)) == NULL) {
+	if ((label = vdev_label_read_config(vd, -1ULL)) == NULL) {
 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
 		    VDEV_AUX_CORRUPT_DATA);
 		return (-1);
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c
index b9436472495d..e573feb5d239 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c
@@ -433,17 +433,22 @@ vdev_top_config_generate(spa_t *spa, nvlist_t *config)
 }
 
 /*
- * Returns the configuration from the label of the given vdev. If 'label' is
- * VDEV_BEST_LABEL, each label of the vdev will be read until a valid
- * configuration is found; otherwise, only the specified label will be read.
+ * Returns the configuration from the label of the given vdev. For vdevs
+ * which don't have a txg value stored on their label (i.e. spares/cache)
+ * or have not been completely initialized (txg = 0) just return
+ * the configuration from the first valid label we find. Otherwise,
+ * find the most up-to-date label that does not exceed the specified
+ * 'txg' value.
  */
 nvlist_t *
-vdev_label_read_config(vdev_t *vd, int label)
+vdev_label_read_config(vdev_t *vd, uint64_t txg)
 {
 	spa_t *spa = vd->vdev_spa;
 	nvlist_t *config = NULL;
 	vdev_phys_t *vp;
 	zio_t *zio;
+	uint64_t best_txg = 0;
+	int error = 0;
 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
 	    ZIO_FLAG_SPECULATIVE;
 
@@ -456,8 +461,7 @@ vdev_label_read_config(vdev_t *vd, int label)
 
 retry:
 	for (int l = 0; l < VDEV_LABELS; l++) {
-		if (label >= 0 && label < VDEV_LABELS && label != l)
-			continue;
+		nvlist_t *label = NULL;
 
 		zio = zio_root(spa, NULL, NULL, flags);
 
@@ -467,12 +471,31 @@ retry:
 
 		if (zio_wait(zio) == 0 &&
 		    nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
-		    &config, 0) == 0)
-			break;
+		    &label, 0) == 0) {
+			uint64_t label_txg = 0;
 
-		if (config != NULL) {
-			nvlist_free(config);
-			config = NULL;
+			/*
+			 * Auxiliary vdevs won't have txg values in their
+			 * labels and newly added vdevs may not have been
+			 * completely initialized so just return the
+			 * configuration from the first valid label we
+			 * encounter.
+			 */
+			error = nvlist_lookup_uint64(label,
+			    ZPOOL_CONFIG_POOL_TXG, &label_txg);
+			if ((error || label_txg == 0) && !config) {
+				config = label;
+				break;
+			} else if (label_txg <= txg && label_txg > best_txg) {
+				best_txg = label_txg;
+				nvlist_free(config);
+				config = fnvlist_dup(label);
+			}
+		}
+
+		if (label != NULL) {
+			nvlist_free(label);
+			label = NULL;
 		}
 	}
 
@@ -507,7 +530,7 @@ vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
 	/*
 	 * Read the label, if any, and perform some basic sanity checks.
 	 */
-	if ((label = vdev_label_read_config(vd, VDEV_BEST_LABEL)) == NULL)
+	if ((label = vdev_label_read_config(vd, -1ULL)) == NULL)
 		return (B_FALSE);
 
 	(void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
@@ -867,7 +890,6 @@ vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
 struct ubl_cbdata {
 	uberblock_t	*ubl_ubbest;	/* Best uberblock */
 	vdev_t		*ubl_vd;	/* vdev associated with the above */
-	int		ubl_label;	/* Label associated with the above */
 };
 
 static void
@@ -886,15 +908,13 @@ vdev_uberblock_load_done(zio_t *zio)
 		if (ub->ub_txg <= spa->spa_load_max_txg &&
 		    vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) {
 			/*
-			 * Keep track of the vdev and label in which this
-			 * uberblock was found. We will use this information
-			 * later to obtain the config nvlist associated with
+			 * Keep track of the vdev in which this uberblock
+			 * was found. We will use this information later
+			 * to obtain the config nvlist associated with
 			 * this uberblock.
 			 */
 			*cbp->ubl_ubbest = *ub;
 			cbp->ubl_vd = vd;
-			cbp->ubl_label = vdev_label_number(vd->vdev_psize,
-			    zio->io_offset);
 		}
 		mutex_exit(&rio->io_lock);
 	}
@@ -926,12 +946,11 @@ vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
  * Reads the 'best' uberblock from disk along with its associated
  * configuration. First, we read the uberblock array of each label of each
  * vdev, keeping track of the uberblock with the highest txg in each array.
- * Then, we read the configuration from the same label as the best uberblock.
+ * Then, we read the configuration from the same vdev as the best uberblock.
  */
 void
 vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
 {
-	int i;
 	zio_t *zio;
 	spa_t *spa = rvd->vdev_spa;
 	struct ubl_cbdata cb;
@@ -951,13 +970,15 @@ vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
 	zio = zio_root(spa, NULL, &cb, flags);
 	vdev_uberblock_load_impl(zio, rvd, flags, &cb);
 	(void) zio_wait(zio);
-	if (cb.ubl_vd != NULL) {
-		for (i = cb.ubl_label % 2; i < VDEV_LABELS; i += 2) {
-			*config = vdev_label_read_config(cb.ubl_vd, i);
-			if (*config != NULL)
-				break;
-		}
-	}
+
+	/*
+	 * It's possible that the best uberblock was discovered on a label
+	 * that has a configuration which was written in a future txg.
+	 * Search all labels on this vdev to find the configuration that
+	 * matches the txg for our uberblock.
+	 */
+	if (cb.ubl_vd != NULL)
+		*config = vdev_label_read_config(cb.ubl_vd, ub->ub_txg);
 	spa_config_exit(spa, SCL_ALL, FTAG);
 }
 
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c
index 515e613c27b7..c6a89c872cdb 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011 by Delphix. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -461,6 +461,37 @@ zil_alloc_lwb(zilog_t *zilog, blkptr_t *bp, uint64_t txg)
 	return (lwb);
 }
 
+/*
+ * Called when we create in-memory log transactions so that we know
+ * to cleanup the itxs at the end of spa_sync().
+ */
+void
+zilog_dirty(zilog_t *zilog, uint64_t txg)
+{
+	dsl_pool_t *dp = zilog->zl_dmu_pool;
+	dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
+
+	if (dsl_dataset_is_snapshot(ds))
+		panic("dirtying snapshot!");
+
+	if (txg_list_add(&dp->dp_dirty_zilogs, zilog, txg) == 0) {
+		/* up the hold count until we can be written out */
+		dmu_buf_add_ref(ds->ds_dbuf, zilog);
+	}
+}
+
+boolean_t
+zilog_is_dirty(zilog_t *zilog)
+{
+	dsl_pool_t *dp = zilog->zl_dmu_pool;
+
+	for (int t = 0; t < TXG_SIZE; t++) {
+		if (txg_list_member(&dp->dp_dirty_zilogs, zilog, t))
+			return (B_TRUE);
+	}
+	return (B_FALSE);
+}
+
 /*
  * Create an on-disk intent log.
  */
@@ -577,14 +608,21 @@ zil_destroy(zilog_t *zilog, boolean_t keep_first)
 			kmem_cache_free(zil_lwb_cache, lwb);
 		}
 	} else if (!keep_first) {
-		(void) zil_parse(zilog, zil_free_log_block,
-		    zil_free_log_record, tx, zh->zh_claim_txg);
+		zil_destroy_sync(zilog, tx);
 	}
 	mutex_exit(&zilog->zl_lock);
 
 	dmu_tx_commit(tx);
 }
 
+void
+zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx)
+{
+	ASSERT(list_is_empty(&zilog->zl_lwb_list));
+	(void) zil_parse(zilog, zil_free_log_block,
+	    zil_free_log_record, tx, zilog->zl_header->zh_claim_txg);
+}
+
 int
 zil_claim(const char *osname, void *txarg)
 {
@@ -998,6 +1036,8 @@ zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb)
 		return (NULL);
 
 	ASSERT(lwb->lwb_buf != NULL);
+	ASSERT(zilog_is_dirty(zilog) ||
+	    spa_freeze_txg(zilog->zl_spa) != UINT64_MAX);
 
 	if (lrc->lrc_txtype == TX_WRITE && itx->itx_wr_state == WR_NEED_COPY)
 		dlen = P2ROUNDUP_TYPED(
@@ -1218,7 +1258,7 @@ zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx)
 	if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_RENAME)
 		zil_async_to_sync(zilog, itx->itx_oid);
 
-	if (spa_freeze_txg(zilog->zl_spa) !=  UINT64_MAX)
+	if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX)
 		txg = ZILTEST_TXG;
 	else
 		txg = dmu_tx_get_txg(tx);
@@ -1269,6 +1309,7 @@ zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx)
 	}
 
 	itx->itx_lr.lrc_txg = dmu_tx_get_txg(tx);
+	zilog_dirty(zilog, txg);
 	mutex_exit(&itxg->itxg_lock);
 
 	/* Release the old itxs now we've dropped the lock */
@@ -1278,7 +1319,10 @@ zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx)
 
 /*
  * If there are any in-memory intent log transactions which have now been
- * synced then start up a taskq to free them.
+ * synced then start up a taskq to free them. We should only do this after we
+ * have written out the uberblocks (i.e. txg has been comitted) so that
+ * don't inadvertently clean out in-memory log records that would be required
+ * by zil_commit().
  */
 void
 zil_clean(zilog_t *zilog, uint64_t synced_txg)
@@ -1746,6 +1790,7 @@ zil_close(zilog_t *zilog)
 	mutex_exit(&zilog->zl_lock);
 	if (txg)
 		txg_wait_synced(zilog->zl_dmu_pool, txg);
+	ASSERT(!zilog_is_dirty(zilog));
 
 	taskq_destroy(zilog->zl_clean_taskq);
 	zilog->zl_clean_taskq = NULL;