Update core ZFS code from build 121 to build 141.

1 files changed, 604 insertions, 402 deletions

diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c
index 5a9d25b77..690e6ecde 100644
--- a/module/zfs/dmu_objset.c
+++ b/module/zfs/dmu_objset.c
@@ -19,10 +19,11 @@
  * 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.
  */
 
+/* Portions Copyright 2010 Robert Milkowski */
+
 #include <sys/cred.h>
 #include <sys/zfs_context.h>
 #include <sys/dmu_objset.h>
@@ -36,22 +37,23 @@
 #include <sys/dbuf.h>
 #include <sys/zvol.h>
 #include <sys/dmu_tx.h>
-#include <sys/zio_checksum.h>
 #include <sys/zap.h>
 #include <sys/zil.h>
 #include <sys/dmu_impl.h>
 #include <sys/zfs_ioctl.h>
+#include <sys/sunddi.h>
+#include <sys/sa.h>
 
 spa_t *
 dmu_objset_spa(objset_t *os)
 {
-	return (os->os->os_spa);
+	return (os->os_spa);
 }
 
 zilog_t *
 dmu_objset_zil(objset_t *os)
 {
-	return (os->os->os_zil);
+	return (os->os_zil);
 }
 
 dsl_pool_t *
@@ -59,82 +61,112 @@ dmu_objset_pool(objset_t *os)
 {
 	dsl_dataset_t *ds;
 
-	if ((ds = os->os->os_dsl_dataset) != NULL && ds->ds_dir)
+	if ((ds = os->os_dsl_dataset) != NULL && ds->ds_dir)
 		return (ds->ds_dir->dd_pool);
 	else
-		return (spa_get_dsl(os->os->os_spa));
+		return (spa_get_dsl(os->os_spa));
 }
 
 dsl_dataset_t *
 dmu_objset_ds(objset_t *os)
 {
-	return (os->os->os_dsl_dataset);
+	return (os->os_dsl_dataset);
 }
 
 dmu_objset_type_t
 dmu_objset_type(objset_t *os)
 {
-	return (os->os->os_phys->os_type);
+	return (os->os_phys->os_type);
 }
 
 void
 dmu_objset_name(objset_t *os, char *buf)
 {
-	dsl_dataset_name(os->os->os_dsl_dataset, buf);
+	dsl_dataset_name(os->os_dsl_dataset, buf);
 }
 
 uint64_t
 dmu_objset_id(objset_t *os)
 {
-	dsl_dataset_t *ds = os->os->os_dsl_dataset;
+	dsl_dataset_t *ds = os->os_dsl_dataset;
 
 	return (ds ? ds->ds_object : 0);
 }
 
+uint64_t
+dmu_objset_syncprop(objset_t *os)
+{
+	return (os->os_sync);
+}
+
+uint64_t
+dmu_objset_logbias(objset_t *os)
+{
+	return (os->os_logbias);
+}
+
 static void
 checksum_changed_cb(void *arg, uint64_t newval)
 {
-	objset_impl_t *osi = arg;
+	objset_t *os = arg;
 
 	/*
 	 * Inheritance should have been done by now.
 	 */
 	ASSERT(newval != ZIO_CHECKSUM_INHERIT);
 
-	osi->os_checksum = zio_checksum_select(newval, ZIO_CHECKSUM_ON_VALUE);
+	os->os_checksum = zio_checksum_select(newval, ZIO_CHECKSUM_ON_VALUE);
 }
 
 static void
 compression_changed_cb(void *arg, uint64_t newval)
 {
-	objset_impl_t *osi = arg;
+	objset_t *os = arg;
 
 	/*
 	 * Inheritance and range checking should have been done by now.
 	 */
 	ASSERT(newval != ZIO_COMPRESS_INHERIT);
 
-	osi->os_compress = zio_compress_select(newval, ZIO_COMPRESS_ON_VALUE);
+	os->os_compress = zio_compress_select(newval, ZIO_COMPRESS_ON_VALUE);
 }
 
 static void
 copies_changed_cb(void *arg, uint64_t newval)
 {
-	objset_impl_t *osi = arg;
+	objset_t *os = arg;
 
 	/*
 	 * Inheritance and range checking should have been done by now.
 	 */
 	ASSERT(newval > 0);
-	ASSERT(newval <= spa_max_replication(osi->os_spa));
+	ASSERT(newval <= spa_max_replication(os->os_spa));
 
-	osi->os_copies = newval;
+	os->os_copies = newval;
+}
+
+static void
+dedup_changed_cb(void *arg, uint64_t newval)
+{
+	objset_t *os = arg;
+	spa_t *spa = os->os_spa;
+	enum zio_checksum checksum;
+
+	/*
+	 * Inheritance should have been done by now.
+	 */
+	ASSERT(newval != ZIO_CHECKSUM_INHERIT);
+
+	checksum = zio_checksum_dedup_select(spa, newval, ZIO_CHECKSUM_OFF);
+
+	os->os_dedup_checksum = checksum & ZIO_CHECKSUM_MASK;
+	os->os_dedup_verify = !!(checksum & ZIO_CHECKSUM_VERIFY);
 }
 
 static void
 primary_cache_changed_cb(void *arg, uint64_t newval)
 {
-	objset_impl_t *osi = arg;
+	objset_t *os = arg;
 
 	/*
 	 * Inheritance and range checking should have been done by now.
@@ -142,13 +174,13 @@ primary_cache_changed_cb(void *arg, uint64_t newval)
 	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
 	    newval == ZFS_CACHE_METADATA);
 
-	osi->os_primary_cache = newval;
+	os->os_primary_cache = newval;
 }
 
 static void
 secondary_cache_changed_cb(void *arg, uint64_t newval)
 {
-	objset_impl_t *osi = arg;
+	objset_t *os = arg;
 
 	/*
 	 * Inheritance and range checking should have been done by now.
@@ -156,7 +188,35 @@ secondary_cache_changed_cb(void *arg, uint64_t newval)
 	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
 	    newval == ZFS_CACHE_METADATA);
 
-	osi->os_secondary_cache = newval;
+	os->os_secondary_cache = newval;
+}
+
+static void
+sync_changed_cb(void *arg, uint64_t newval)
+{
+	objset_t *os = arg;
+
+	/*
+	 * Inheritance and range checking should have been done by now.
+	 */
+	ASSERT(newval == ZFS_SYNC_STANDARD || newval == ZFS_SYNC_ALWAYS ||
+	    newval == ZFS_SYNC_DISABLED);
+
+	os->os_sync = newval;
+	if (os->os_zil)
+		zil_set_sync(os->os_zil, newval);
+}
+
+static void
+logbias_changed_cb(void *arg, uint64_t newval)
+{
+	objset_t *os = arg;
+
+	ASSERT(newval == ZFS_LOGBIAS_LATENCY ||
+	    newval == ZFS_LOGBIAS_THROUGHPUT);
+	os->os_logbias = newval;
+	if (os->os_zil)
+		zil_set_logbias(os->os_zil, newval);
 }
 
 void
@@ -177,39 +237,37 @@ dmu_objset_byteswap(void *buf, size_t size)
 
 int
 dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
-    objset_impl_t **osip)
+    objset_t **osp)
 {
-	objset_impl_t *osi;
+	objset_t *os;
 	int i, err;
 
 	ASSERT(ds == NULL || MUTEX_HELD(&ds->ds_opening_lock));
 
-	osi = kmem_zalloc(sizeof (objset_impl_t), KM_SLEEP);
-	osi->os.os = osi;
-	osi->os_dsl_dataset = ds;
-	osi->os_spa = spa;
-	osi->os_rootbp = bp;
-	if (!BP_IS_HOLE(osi->os_rootbp)) {
+	os = kmem_zalloc(sizeof (objset_t), KM_SLEEP);
+	os->os_dsl_dataset = ds;
+	os->os_spa = spa;
+	os->os_rootbp = bp;
+	if (!BP_IS_HOLE(os->os_rootbp)) {
 		uint32_t aflags = ARC_WAIT;
 		zbookmark_t zb;
-		zb.zb_objset = ds ? ds->ds_object : 0;
-		zb.zb_object = 0;
-		zb.zb_level = -1;
-		zb.zb_blkid = 0;
-		if (DMU_OS_IS_L2CACHEABLE(osi))
+		SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
+		    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
+
+		if (DMU_OS_IS_L2CACHEABLE(os))
 			aflags |= ARC_L2CACHE;
 
-		dprintf_bp(osi->os_rootbp, "reading %s", "");
+		dprintf_bp(os->os_rootbp, "reading %s", "");
 		/*
-		 * NB: when bprewrite scrub can change the bp,
+		 * XXX when bprewrite scrub can change the bp,
 		 * and this is called from dmu_objset_open_ds_os, the bp
 		 * could change, and we'll need a lock.
 		 */
-		err = arc_read_nolock(NULL, spa, osi->os_rootbp,
-		    arc_getbuf_func, &osi->os_phys_buf,
+		err = dsl_read_nolock(NULL, spa, os->os_rootbp,
+		    arc_getbuf_func, &os->os_phys_buf,
 		    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &aflags, &zb);
 		if (err) {
-			kmem_free(osi, sizeof (objset_impl_t));
+			kmem_free(os, sizeof (objset_t));
 			/* convert checksum errors into IO errors */
 			if (err == ECKSUM)
 				err = EIO;
@@ -218,27 +276,27 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
 
 		/* Increase the blocksize if we are permitted. */
 		if (spa_version(spa) >= SPA_VERSION_USERSPACE &&
-		    arc_buf_size(osi->os_phys_buf) < sizeof (objset_phys_t)) {
+		    arc_buf_size(os->os_phys_buf) < sizeof (objset_phys_t)) {
 			arc_buf_t *buf = arc_buf_alloc(spa,
-			    sizeof (objset_phys_t), &osi->os_phys_buf,
+			    sizeof (objset_phys_t), &os->os_phys_buf,
 			    ARC_BUFC_METADATA);
 			bzero(buf->b_data, sizeof (objset_phys_t));
-			bcopy(osi->os_phys_buf->b_data, buf->b_data,
-			    arc_buf_size(osi->os_phys_buf));
-			(void) arc_buf_remove_ref(osi->os_phys_buf,
-			    &osi->os_phys_buf);
-			osi->os_phys_buf = buf;
+			bcopy(os->os_phys_buf->b_data, buf->b_data,
+			    arc_buf_size(os->os_phys_buf));
+			(void) arc_buf_remove_ref(os->os_phys_buf,
+			    &os->os_phys_buf);
+			os->os_phys_buf = buf;
 		}
 
-		osi->os_phys = osi->os_phys_buf->b_data;
-		osi->os_flags = osi->os_phys->os_flags;
+		os->os_phys = os->os_phys_buf->b_data;
+		os->os_flags = os->os_phys->os_flags;
 	} else {
 		int size = spa_version(spa) >= SPA_VERSION_USERSPACE ?
 		    sizeof (objset_phys_t) : OBJSET_OLD_PHYS_SIZE;
-		osi->os_phys_buf = arc_buf_alloc(spa, size,
-		    &osi->os_phys_buf, ARC_BUFC_METADATA);
-		osi->os_phys = osi->os_phys_buf->b_data;
-		bzero(osi->os_phys, size);
+		os->os_phys_buf = arc_buf_alloc(spa, size,
+		    &os->os_phys_buf, ARC_BUFC_METADATA);
+		os->os_phys = os->os_phys_buf->b_data;
+		bzero(os->os_phys, size);
 	}
 
 	/*
@@ -249,61 +307,74 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
 	 */
 	if (ds) {
 		err = dsl_prop_register(ds, "primarycache",
-		    primary_cache_changed_cb, osi);
+		    primary_cache_changed_cb, os);
 		if (err == 0)
 			err = dsl_prop_register(ds, "secondarycache",
-			    secondary_cache_changed_cb, osi);
+			    secondary_cache_changed_cb, os);
 		if (!dsl_dataset_is_snapshot(ds)) {
 			if (err == 0)
 				err = dsl_prop_register(ds, "checksum",
-				    checksum_changed_cb, osi);
+				    checksum_changed_cb, os);
 			if (err == 0)
 				err = dsl_prop_register(ds, "compression",
-				    compression_changed_cb, osi);
+				    compression_changed_cb, os);
 			if (err == 0)
 				err = dsl_prop_register(ds, "copies",
-				    copies_changed_cb, osi);
+				    copies_changed_cb, os);
+			if (err == 0)
+				err = dsl_prop_register(ds, "dedup",
+				    dedup_changed_cb, os);
+			if (err == 0)
+				err = dsl_prop_register(ds, "logbias",
+				    logbias_changed_cb, os);
+			if (err == 0)
+				err = dsl_prop_register(ds, "sync",
+				    sync_changed_cb, os);
 		}
 		if (err) {
-			VERIFY(arc_buf_remove_ref(osi->os_phys_buf,
-			    &osi->os_phys_buf) == 1);
-			kmem_free(osi, sizeof (objset_impl_t));
+			VERIFY(arc_buf_remove_ref(os->os_phys_buf,
+			    &os->os_phys_buf) == 1);
+			kmem_free(os, sizeof (objset_t));
 			return (err);
 		}
 	} else if (ds == NULL) {
 		/* It's the meta-objset. */
-		osi->os_checksum = ZIO_CHECKSUM_FLETCHER_4;
-		osi->os_compress = ZIO_COMPRESS_LZJB;
-		osi->os_copies = spa_max_replication(spa);
-		osi->os_primary_cache = ZFS_CACHE_ALL;
-		osi->os_secondary_cache = ZFS_CACHE_ALL;
+		os->os_checksum = ZIO_CHECKSUM_FLETCHER_4;
+		os->os_compress = ZIO_COMPRESS_LZJB;
+		os->os_copies = spa_max_replication(spa);
+		os->os_dedup_checksum = ZIO_CHECKSUM_OFF;
+		os->os_dedup_verify = 0;
+		os->os_logbias = 0;
+		os->os_sync = 0;
+		os->os_primary_cache = ZFS_CACHE_ALL;
+		os->os_secondary_cache = ZFS_CACHE_ALL;
 	}
 
-	osi->os_zil_header = osi->os_phys->os_zil_header;
-	osi->os_zil = zil_alloc(&osi->os, &osi->os_zil_header);
+	os->os_zil_header = os->os_phys->os_zil_header;
+	os->os_zil = zil_alloc(os, &os->os_zil_header);
 
 	for (i = 0; i < TXG_SIZE; i++) {
-		list_create(&osi->os_dirty_dnodes[i], sizeof (dnode_t),
+		list_create(&os->os_dirty_dnodes[i], sizeof (dnode_t),
 		    offsetof(dnode_t, dn_dirty_link[i]));
-		list_create(&osi->os_free_dnodes[i], sizeof (dnode_t),
+		list_create(&os->os_free_dnodes[i], sizeof (dnode_t),
 		    offsetof(dnode_t, dn_dirty_link[i]));
 	}
-	list_create(&osi->os_dnodes, sizeof (dnode_t),
+	list_create(&os->os_dnodes, sizeof (dnode_t),
 	    offsetof(dnode_t, dn_link));
-	list_create(&osi->os_downgraded_dbufs, sizeof (dmu_buf_impl_t),
+	list_create(&os->os_downgraded_dbufs, sizeof (dmu_buf_impl_t),
 	    offsetof(dmu_buf_impl_t, db_link));
 
-	mutex_init(&osi->os_lock, NULL, MUTEX_DEFAULT, NULL);
-	mutex_init(&osi->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
-	mutex_init(&osi->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);
-
-	osi->os_meta_dnode = dnode_special_open(osi,
-	    &osi->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT);
-	if (arc_buf_size(osi->os_phys_buf) >= sizeof (objset_phys_t)) {
-		osi->os_userused_dnode = dnode_special_open(osi,
-		    &osi->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT);
-		osi->os_groupused_dnode = dnode_special_open(osi,
-		    &osi->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT);
+	mutex_init(&os->os_lock, NULL, MUTEX_DEFAULT, NULL);
+	mutex_init(&os->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
+	mutex_init(&os->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);
+
+	os->os_meta_dnode = dnode_special_open(os,
+	    &os->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT);
+	if (arc_buf_size(os->os_phys_buf) >= sizeof (objset_phys_t)) {
+		os->os_userused_dnode = dnode_special_open(os,
+		    &os->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT);
+		os->os_groupused_dnode = dnode_special_open(os,
+		    &os->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT);
 	}
 
 	/*
@@ -311,117 +382,96 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
 	 * have ds_opening_lock
 	 */
 	if (ds) {
-		VERIFY(NULL == dsl_dataset_set_user_ptr(ds, osi,
-		    dmu_objset_evict));
+		mutex_enter(&ds->ds_lock);
+		ASSERT(ds->ds_objset == NULL);
+		ds->ds_objset = os;
+		mutex_exit(&ds->ds_lock);
 	}
 
-	*osip = osi;
+	*osp = os;
 	return (0);
 }
 
-static int
-dmu_objset_open_ds_os(dsl_dataset_t *ds, objset_t *os, dmu_objset_type_t type)
+int
+dmu_objset_from_ds(dsl_dataset_t *ds, objset_t **osp)
 {
-	objset_impl_t *osi;
+	int err = 0;
 
 	mutex_enter(&ds->ds_opening_lock);
-	osi = dsl_dataset_get_user_ptr(ds);
-	if (osi == NULL) {
-		int err;
-
+	*osp = ds->ds_objset;
+	if (*osp == NULL) {
 		err = dmu_objset_open_impl(dsl_dataset_get_spa(ds),
-		    ds, &ds->ds_phys->ds_bp, &osi);
-		if (err) {
-			mutex_exit(&ds->ds_opening_lock);
-			return (err);
-		}
+		    ds, &ds->ds_phys->ds_bp, osp);
 	}
 	mutex_exit(&ds->ds_opening_lock);
-
-	os->os = osi;
-	os->os_mode = DS_MODE_NOHOLD;
-
-	if (type != DMU_OST_ANY && type != os->os->os_phys->os_type)
-		return (EINVAL);
-	return (0);
+	return (err);
 }
 
+/* called from zpl */
 int
-dmu_objset_open_ds(dsl_dataset_t *ds, dmu_objset_type_t type, objset_t **osp)
+dmu_objset_hold(const char *name, void *tag, objset_t **osp)
 {
-	objset_t *os;
+	dsl_dataset_t *ds;
 	int err;
 
-	os = kmem_alloc(sizeof (objset_t), KM_SLEEP);
-	err = dmu_objset_open_ds_os(ds, os, type);
+	err = dsl_dataset_hold(name, tag, &ds);
 	if (err)
-		kmem_free(os, sizeof (objset_t));
-	else
-		*osp = os;
+		return (err);
+
+	err = dmu_objset_from_ds(ds, osp);
+	if (err)
+		dsl_dataset_rele(ds, tag);
+
 	return (err);
 }
 
 /* called from zpl */
 int
-dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
-    objset_t **osp)
+dmu_objset_own(const char *name, dmu_objset_type_t type,
+    boolean_t readonly, void *tag, objset_t **osp)
 {
-	objset_t *os;
 	dsl_dataset_t *ds;
 	int err;
 
-	ASSERT(DS_MODE_TYPE(mode) == DS_MODE_USER ||
-	    DS_MODE_TYPE(mode) == DS_MODE_OWNER);
-
-	os = kmem_alloc(sizeof (objset_t), KM_SLEEP);
-	if (DS_MODE_TYPE(mode) == DS_MODE_USER)
-		err = dsl_dataset_hold(name, os, &ds);
-	else
-		err = dsl_dataset_own(name, mode, os, &ds);
-	if (err) {
-		kmem_free(os, sizeof (objset_t));
+	err = dsl_dataset_own(name, B_FALSE, tag, &ds);
+	if (err)
 		return (err);
-	}
 
-	err = dmu_objset_open_ds_os(ds, os, type);
+	err = dmu_objset_from_ds(ds, osp);
 	if (err) {
-		if (DS_MODE_TYPE(mode) == DS_MODE_USER)
-			dsl_dataset_rele(ds, os);
-		else
-			dsl_dataset_disown(ds, os);
-		kmem_free(os, sizeof (objset_t));
-	} else {
-		os->os_mode = mode;
-		*osp = os;
+		dsl_dataset_disown(ds, tag);
+	} else if (type != DMU_OST_ANY && type != (*osp)->os_phys->os_type) {
+		dmu_objset_disown(*osp, tag);
+		return (EINVAL);
+	} else if (!readonly && dsl_dataset_is_snapshot(ds)) {
+		dmu_objset_disown(*osp, tag);
+		return (EROFS);
 	}
 	return (err);
 }
 
 void
-dmu_objset_close(objset_t *os)
+dmu_objset_rele(objset_t *os, void *tag)
 {
-	ASSERT(DS_MODE_TYPE(os->os_mode) == DS_MODE_USER ||
-	    DS_MODE_TYPE(os->os_mode) == DS_MODE_OWNER ||
-	    DS_MODE_TYPE(os->os_mode) == DS_MODE_NOHOLD);
+	dsl_dataset_rele(os->os_dsl_dataset, tag);
+}
 
-	if (DS_MODE_TYPE(os->os_mode) == DS_MODE_USER)
-		dsl_dataset_rele(os->os->os_dsl_dataset, os);
-	else if (DS_MODE_TYPE(os->os_mode) == DS_MODE_OWNER)
-		dsl_dataset_disown(os->os->os_dsl_dataset, os);
-	kmem_free(os, sizeof (objset_t));
+void
+dmu_objset_disown(objset_t *os, void *tag)
+{
+	dsl_dataset_disown(os->os_dsl_dataset, tag);
 }
 
 int
 dmu_objset_evict_dbufs(objset_t *os)
 {
-	objset_impl_t *osi = os->os;
 	dnode_t *dn;
 
-	mutex_enter(&osi->os_lock);
+	mutex_enter(&os->os_lock);
 
 	/* process the mdn last, since the other dnodes have holds on it */
-	list_remove(&osi->os_dnodes, osi->os_meta_dnode);
-	list_insert_tail(&osi->os_dnodes, osi->os_meta_dnode);
+	list_remove(&os->os_dnodes, os->os_meta_dnode);
+	list_insert_tail(&os->os_dnodes, os->os_meta_dnode);
 
 	/*
 	 * Find the first dnode with holds.  We have to do this dance
@@ -429,93 +479,103 @@ dmu_objset_evict_dbufs(objset_t *os)
 	 * hold.  If there are no holds then it has no dbufs so OK to
 	 * skip.
 	 */
-	for (dn = list_head(&osi->os_dnodes);
+	for (dn = list_head(&os->os_dnodes);
 	    dn && !dnode_add_ref(dn, FTAG);
-	    dn = list_next(&osi->os_dnodes, dn))
+	    dn = list_next(&os->os_dnodes, dn))
 		continue;
 
 	while (dn) {
 		dnode_t *next_dn = dn;
 
 		do {
-			next_dn = list_next(&osi->os_dnodes, next_dn);
+			next_dn = list_next(&os->os_dnodes, next_dn);
 		} while (next_dn && !dnode_add_ref(next_dn, FTAG));
 
-		mutex_exit(&osi->os_lock);
+		mutex_exit(&os->os_lock);
 		dnode_evict_dbufs(dn);
 		dnode_rele(dn, FTAG);
-		mutex_enter(&osi->os_lock);
+		mutex_enter(&os->os_lock);
 		dn = next_dn;
 	}
-	mutex_exit(&osi->os_lock);
-	return (list_head(&osi->os_dnodes) != osi->os_meta_dnode);
+	mutex_exit(&os->os_lock);
+	return (list_head(&os->os_dnodes) != os->os_meta_dnode);
 }
 
 void
-dmu_objset_evict(dsl_dataset_t *ds, void *arg)
+dmu_objset_evict(objset_t *os)
 {
-	objset_impl_t *osi = arg;
-	objset_t os;
-	int i;
+	dsl_dataset_t *ds = os->os_dsl_dataset;
 
-	for (i = 0; i < TXG_SIZE; i++) {
-		ASSERT(list_head(&osi->os_dirty_dnodes[i]) == NULL);
-		ASSERT(list_head(&osi->os_free_dnodes[i]) == NULL);
-	}
+	for (int t = 0; t < TXG_SIZE; t++)
+		ASSERT(!dmu_objset_is_dirty(os, t));
 
 	if (ds) {
 		if (!dsl_dataset_is_snapshot(ds)) {
 			VERIFY(0 == dsl_prop_unregister(ds, "checksum",
-			    checksum_changed_cb, osi));
+			    checksum_changed_cb, os));
 			VERIFY(0 == dsl_prop_unregister(ds, "compression",
-			    compression_changed_cb, osi));
+			    compression_changed_cb, os));
 			VERIFY(0 == dsl_prop_unregister(ds, "copies",
-			    copies_changed_cb, osi));
+			    copies_changed_cb, os));
+			VERIFY(0 == dsl_prop_unregister(ds, "dedup",
+			    dedup_changed_cb, os));
+			VERIFY(0 == dsl_prop_unregister(ds, "logbias",
+			    logbias_changed_cb, os));
+			VERIFY(0 == dsl_prop_unregister(ds, "sync",
+			    sync_changed_cb, os));
 		}
 		VERIFY(0 == dsl_prop_unregister(ds, "primarycache",
-		    primary_cache_changed_cb, osi));
+		    primary_cache_changed_cb, os));
 		VERIFY(0 == dsl_prop_unregister(ds, "secondarycache",
-		    secondary_cache_changed_cb, osi));
+		    secondary_cache_changed_cb, os));
 	}
 
+	if (os->os_sa)
+		sa_tear_down(os);
+
 	/*
 	 * We should need only a single pass over the dnode list, since
 	 * nothing can be added to the list at this point.
 	 */
-	os.os = osi;
-	(void) dmu_objset_evict_dbufs(&os);
+	(void) dmu_objset_evict_dbufs(os);
 
-	dnode_special_close(osi->os_meta_dnode);
-	if (osi->os_userused_dnode) {
-		dnode_special_close(osi->os_userused_dnode);
-		dnode_special_close(osi->os_groupused_dnode);
+	dnode_special_close(os->os_meta_dnode);
+	if (os->os_userused_dnode) {
+		dnode_special_close(os->os_userused_dnode);
+		dnode_special_close(os->os_groupused_dnode);
 	}
-	zil_free(osi->os_zil);
+	zil_free(os->os_zil);
+
+	ASSERT3P(list_head(&os->os_dnodes), ==, NULL);
 
-	ASSERT3P(list_head(&osi->os_dnodes), ==, NULL);
+	VERIFY(arc_buf_remove_ref(os->os_phys_buf, &os->os_phys_buf) == 1);
+	mutex_destroy(&os->os_lock);
+	mutex_destroy(&os->os_obj_lock);
+	mutex_destroy(&os->os_user_ptr_lock);
+	kmem_free(os, sizeof (objset_t));
+}
 
-	VERIFY(arc_buf_remove_ref(osi->os_phys_buf, &osi->os_phys_buf) == 1);
-	mutex_destroy(&osi->os_lock);
-	mutex_destroy(&osi->os_obj_lock);
-	mutex_destroy(&osi->os_user_ptr_lock);
-	kmem_free(osi, sizeof (objset_impl_t));
+timestruc_t
+dmu_objset_snap_cmtime(objset_t *os)
+{
+	return (dsl_dir_snap_cmtime(os->os_dsl_dataset->ds_dir));
 }
 
 /* called from dsl for meta-objset */
-objset_impl_t *
+objset_t *
 dmu_objset_create_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
     dmu_objset_type_t type, dmu_tx_t *tx)
 {
-	objset_impl_t *osi;
+	objset_t *os;
 	dnode_t *mdn;
 
 	ASSERT(dmu_tx_is_syncing(tx));
 	if (ds)
 		mutex_enter(&ds->ds_opening_lock);
-	VERIFY(0 == dmu_objset_open_impl(spa, ds, bp, &osi));
+	VERIFY(0 == dmu_objset_open_impl(spa, ds, bp, &os));
 	if (ds)
 		mutex_exit(&ds->ds_opening_lock);
-	mdn = osi->os_meta_dnode;
+	mdn = os->os_meta_dnode;
 
 	dnode_allocate(mdn, DMU_OT_DNODE, 1 << DNODE_BLOCK_SHIFT,
 	    DN_MAX_INDBLKSHIFT, DMU_OT_NONE, 0, tx);
@@ -550,24 +610,25 @@ dmu_objset_create_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
 	ASSERT(type != DMU_OST_NONE);
 	ASSERT(type != DMU_OST_ANY);
 	ASSERT(type < DMU_OST_NUMTYPES);
-	osi->os_phys->os_type = type;
-	if (dmu_objset_userused_enabled(osi)) {
-		osi->os_phys->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
-		osi->os_flags = osi->os_phys->os_flags;
+	os->os_phys->os_type = type;
+	if (dmu_objset_userused_enabled(os)) {
+		os->os_phys->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
+		os->os_flags = os->os_phys->os_flags;
 	}
 
 	dsl_dataset_dirty(ds, tx);
 
-	return (osi);
+	return (os);
 }
 
 struct oscarg {
 	void (*userfunc)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
 	void *userarg;
-	dsl_dataset_t *clone_parent;
+	dsl_dataset_t *clone_origin;
 	const char *lastname;
 	dmu_objset_type_t type;
 	uint64_t flags;
+	cred_t *cr;
 };
 
 /*ARGSUSED*/
@@ -585,17 +646,13 @@ dmu_objset_create_check(void *arg1, void *arg2, dmu_tx_t *tx)
 	if (err != ENOENT)
 		return (err ? err : EEXIST);
 
-	if (oa->clone_parent != NULL) {
-		/*
-		 * You can't clone across pools.
-		 */
-		if (oa->clone_parent->ds_dir->dd_pool != dd->dd_pool)
+	if (oa->clone_origin != NULL) {
+		/* You can't clone across pools. */
+		if (oa->clone_origin->ds_dir->dd_pool != dd->dd_pool)
 			return (EXDEV);
 
-		/*
-		 * You can only clone snapshots, not the head datasets.
-		 */
-		if (oa->clone_parent->ds_phys->ds_num_children == 0)
+		/* You can only clone snapshots, not the head datasets. */
+		if (!dsl_dataset_is_snapshot(oa->clone_origin))
 			return (EINVAL);
 	}
 
@@ -603,41 +660,41 @@ dmu_objset_create_check(void *arg1, void *arg2, dmu_tx_t *tx)
 }
 
 static void
-dmu_objset_create_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+dmu_objset_create_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	dsl_dir_t *dd = arg1;
 	struct oscarg *oa = arg2;
-	dsl_dataset_t *ds;
-	blkptr_t *bp;
 	uint64_t dsobj;
 
 	ASSERT(dmu_tx_is_syncing(tx));
 
 	dsobj = dsl_dataset_create_sync(dd, oa->lastname,
-	    oa->clone_parent, oa->flags, cr, tx);
+	    oa->clone_origin, oa->flags, oa->cr, tx);
 
-	VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool, dsobj, FTAG, &ds));
-	bp = dsl_dataset_get_blkptr(ds);
-	if (BP_IS_HOLE(bp)) {
-		objset_impl_t *osi;
+	if (oa->clone_origin == NULL) {
+		dsl_dataset_t *ds;
+		blkptr_t *bp;
+		objset_t *os;
 
-		/* This is an empty dmu_objset; not a clone. */
-		osi = dmu_objset_create_impl(dsl_dataset_get_spa(ds),
+		VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool, dsobj,
+		    FTAG, &ds));
+		bp = dsl_dataset_get_blkptr(ds);
+		ASSERT(BP_IS_HOLE(bp));
+
+		os = dmu_objset_create_impl(dsl_dataset_get_spa(ds),
 		    ds, bp, oa->type, tx);
 
 		if (oa->userfunc)
-			oa->userfunc(&osi->os, oa->userarg, cr, tx);
+			oa->userfunc(os, oa->userarg, oa->cr, tx);
+		dsl_dataset_rele(ds, FTAG);
 	}
 
-	spa_history_internal_log(LOG_DS_CREATE, dd->dd_pool->dp_spa,
-	    tx, cr, "dataset = %llu", dsobj);
-
-	dsl_dataset_rele(ds, FTAG);
+	spa_history_log_internal(LOG_DS_CREATE, dd->dd_pool->dp_spa,
+	    tx, "dataset = %llu", dsobj);
 }
 
 int
-dmu_objset_create(const char *name, dmu_objset_type_t type,
-    objset_t *clone_parent, uint64_t flags,
+dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg)
 {
 	dsl_dir_t *pdd;
@@ -654,24 +711,13 @@ dmu_objset_create(const char *name, dmu_objset_type_t type,
 		return (EEXIST);
 	}
 
-	dprintf("name=%s\n", name);
-
 	oa.userfunc = func;
 	oa.userarg = arg;
 	oa.lastname = tail;
 	oa.type = type;
 	oa.flags = flags;
+	oa.cr = CRED();
 
-	if (clone_parent != NULL) {
-		/*
-		 * You can't clone to a different type.
-		 */
-		if (clone_parent->os->os_phys->os_type != type) {
-			dsl_dir_close(pdd, FTAG);
-			return (EINVAL);
-		}
-		oa.clone_parent = clone_parent->os->os_dsl_dataset;
-	}
 	err = dsl_sync_task_do(pdd->dd_pool, dmu_objset_create_check,
 	    dmu_objset_create_sync, pdd, &oa, 5);
 	dsl_dir_close(pdd, FTAG);
@@ -679,66 +725,63 @@ dmu_objset_create(const char *name, dmu_objset_type_t type,
 }
 
 int
-dmu_objset_destroy(const char *name, boolean_t defer)
+dmu_objset_clone(const char *name, dsl_dataset_t *clone_origin, uint64_t flags)
 {
-	objset_t *os;
-	int error;
-
-	/*
-	 * If it looks like we'll be able to destroy it, and there's
-	 * an unplayed replay log sitting around, destroy the log.
-	 * It would be nicer to do this in dsl_dataset_destroy_sync(),
-	 * but the replay log objset is modified in open context.
-	 */
-	error = dmu_objset_open(name, DMU_OST_ANY,
-	    DS_MODE_OWNER|DS_MODE_READONLY|DS_MODE_INCONSISTENT, &os);
-	if (error == 0) {
-		dsl_dataset_t *ds = os->os->os_dsl_dataset;
-		zil_destroy(dmu_objset_zil(os), B_FALSE);
+	dsl_dir_t *pdd;
+	const char *tail;
+	int err = 0;
+	struct oscarg oa = { 0 };
 
-		error = dsl_dataset_destroy(ds, os, defer);
-		/*
-		 * dsl_dataset_destroy() closes the ds.
-		 */
-		kmem_free(os, sizeof (objset_t));
+	ASSERT(strchr(name, '@') == NULL);
+	err = dsl_dir_open(name, FTAG, &pdd, &tail);
+	if (err)
+		return (err);
+	if (tail == NULL) {
+		dsl_dir_close(pdd, FTAG);
+		return (EEXIST);
 	}
 
-	return (error);
+	oa.lastname = tail;
+	oa.clone_origin = clone_origin;
+	oa.flags = flags;
+	oa.cr = CRED();
+
+	err = dsl_sync_task_do(pdd->dd_pool, dmu_objset_create_check,
+	    dmu_objset_create_sync, pdd, &oa, 5);
+	dsl_dir_close(pdd, FTAG);
+	return (err);
 }
 
-/*
- * This will close the objset.
- */
 int
-dmu_objset_rollback(objset_t *os)
+dmu_objset_destroy(const char *name, boolean_t defer)
 {
-	int err;
 	dsl_dataset_t *ds;
-
-	ds = os->os->os_dsl_dataset;
-
-	if (!dsl_dataset_tryown(ds, TRUE, os)) {
-		dmu_objset_close(os);
-		return (EBUSY);
-	}
-
-	err = dsl_dataset_rollback(ds, os->os->os_phys->os_type);
+	int error;
 
 	/*
-	 * NB: we close the objset manually because the rollback
-	 * actually implicitly called dmu_objset_evict(), thus freeing
-	 * the objset_impl_t.
+	 * dsl_dataset_destroy() can free any claimed-but-unplayed
+	 * intent log, but if there is an active log, it has blocks that
+	 * are allocated, but may not yet be reflected in the on-disk
+	 * structure.  Only the ZIL knows how to free them, so we have
+	 * to call into it here.
 	 */
-	dsl_dataset_disown(ds, os);
-	kmem_free(os, sizeof (objset_t));
-	return (err);
+	error = dsl_dataset_own(name, B_TRUE, FTAG, &ds);
+	if (error == 0) {
+		objset_t *os;
+		if (dmu_objset_from_ds(ds, &os) == 0)
+			zil_destroy(dmu_objset_zil(os), B_FALSE);
+		error = dsl_dataset_destroy(ds, FTAG, defer);
+		/* dsl_dataset_destroy() closes the ds. */
+	}
+
+	return (error);
 }
 
 struct snaparg {
 	dsl_sync_task_group_t *dstg;
 	char *snapname;
 	char failed[MAXPATHLEN];
-	boolean_t checkperms;
+	boolean_t recursive;
 	nvlist_t *props;
 };
 
@@ -750,49 +793,68 @@ snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
 
 	/* The props have already been checked by zfs_check_userprops(). */
 
-	return (dsl_dataset_snapshot_check(os->os->os_dsl_dataset,
+	return (dsl_dataset_snapshot_check(os->os_dsl_dataset,
 	    sn->snapname, tx));
 }
 
 static void
-snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+snapshot_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 {
 	objset_t *os = arg1;
-	dsl_dataset_t *ds = os->os->os_dsl_dataset;
+	dsl_dataset_t *ds = os->os_dsl_dataset;
 	struct snaparg *sn = arg2;
 
-	dsl_dataset_snapshot_sync(ds, sn->snapname, cr, tx);
+	dsl_dataset_snapshot_sync(ds, sn->snapname, tx);
 
-	if (sn->props)
-		dsl_props_set_sync(ds->ds_prev, sn->props, cr, tx);
+	if (sn->props) {
+		dsl_props_arg_t pa;
+		pa.pa_props = sn->props;
+		pa.pa_source = ZPROP_SRC_LOCAL;
+		dsl_props_set_sync(ds->ds_prev, &pa, tx);
+	}
 }
 
 static int
-dmu_objset_snapshot_one(char *name, void *arg)
+dmu_objset_snapshot_one(const char *name, void *arg)
 {
 	struct snaparg *sn = arg;
 	objset_t *os;
 	int err;
+	char *cp;
+
+	/*
+	 * If the objset starts with a '%', then ignore it unless it was
+	 * explicitly named (ie, not recursive).  These hidden datasets
+	 * are always inconsistent, and by not opening them here, we can
+	 * avoid a race with dsl_dir_destroy_check().
+	 */
+	cp = strrchr(name, '/');
+	if (cp && cp[1] == '%' && sn->recursive)
+		return (0);
 
 	(void) strcpy(sn->failed, name);
 
 	/*
-	 * Check permissions only when requested.  This only applies when
-	 * doing a recursive snapshot.  The permission checks for the starting
-	 * dataset have already been performed in zfs_secpolicy_snapshot()
+	 * Check permissions if we are doing a recursive snapshot.  The
+	 * permission checks for the starting dataset have already been
+	 * performed in zfs_secpolicy_snapshot()
 	 */
-	if (sn->checkperms == B_TRUE &&
-	    (err = zfs_secpolicy_snapshot_perms(name, CRED())))
+	if (sn->recursive && (err = zfs_secpolicy_snapshot_perms(name, CRED())))
 		return (err);
 
-	err = dmu_objset_open(name, DMU_OST_ANY, DS_MODE_USER, &os);
+	err = dmu_objset_hold(name, sn, &os);
 	if (err != 0)
 		return (err);
 
-	/* If the objset is in an inconsistent state, return busy */
-	if (os->os->os_dsl_dataset->ds_phys->ds_flags & DS_FLAG_INCONSISTENT) {
-		dmu_objset_close(os);
-		return (EBUSY);
+	/*
+	 * If the objset is in an inconsistent state (eg, in the process
+	 * of being destroyed), don't snapshot it.  As with %hidden
+	 * datasets, we return EBUSY if this name was explicitly
+	 * requested (ie, not recursive), and otherwise ignore it.
+	 */
+	if (os->os_dsl_dataset->ds_phys->ds_flags & DS_FLAG_INCONSISTENT) {
+		dmu_objset_rele(os, sn);
+		return (sn->recursive ? 0 : EBUSY);
 	}
 
 	/*
@@ -805,7 +867,7 @@ dmu_objset_snapshot_one(char *name, void *arg)
 		dsl_sync_task_create(sn->dstg, snapshot_check,
 		    snapshot_sync, os, sn, 3);
 	} else {
-		dmu_objset_close(os);
+		dmu_objset_rele(os, sn);
 	}
 
 	return (err);
@@ -829,13 +891,12 @@ dmu_objset_snapshot(char *fsname, char *snapname,
 	sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
 	sn.snapname = snapname;
 	sn.props = props;
+	sn.recursive = recursive;
 
 	if (recursive) {
-		sn.checkperms = B_TRUE;
 		err = dmu_objset_find(fsname,
 		    dmu_objset_snapshot_one, &sn, DS_FIND_CHILDREN);
 	} else {
-		sn.checkperms = B_FALSE;
 		err = dmu_objset_snapshot_one(fsname, &sn);
 	}
 
@@ -845,11 +906,11 @@ dmu_objset_snapshot(char *fsname, char *snapname,
 	for (dst = list_head(&sn.dstg->dstg_tasks); dst;
 	    dst = list_next(&sn.dstg->dstg_tasks, dst)) {
 		objset_t *os = dst->dst_arg1;
-		dsl_dataset_t *ds = os->os->os_dsl_dataset;
+		dsl_dataset_t *ds = os->os_dsl_dataset;
 		if (dst->dst_err)
 			dsl_dataset_name(ds, sn.failed);
 		zil_resume(dmu_objset_zil(os));
-		dmu_objset_close(os);
+		dmu_objset_rele(os, &sn);
 	}
 
 	if (err)
@@ -888,11 +949,10 @@ dmu_objset_sync_dnodes(list_t *list, list_t *newlist, dmu_tx_t *tx)
 
 /* ARGSUSED */
 static void
-ready(zio_t *zio, arc_buf_t *abuf, void *arg)
+dmu_objset_write_ready(zio_t *zio, arc_buf_t *abuf, void *arg)
 {
 	blkptr_t *bp = zio->io_bp;
-	blkptr_t *bp_orig = &zio->io_bp_orig;
-	objset_impl_t *os = arg;
+	objset_t *os = arg;
 	dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;
 
 	ASSERT(bp == os->os_rootbp);
@@ -908,24 +968,34 @@ ready(zio_t *zio, arc_buf_t *abuf, void *arg)
 	bp->blk_fill = 0;
 	for (int i = 0; i < dnp->dn_nblkptr; i++)
 		bp->blk_fill += dnp->dn_blkptr[i].blk_fill;
+}
+
+/* ARGSUSED */
+static void
+dmu_objset_write_done(zio_t *zio, arc_buf_t *abuf, void *arg)
+{
+	blkptr_t *bp = zio->io_bp;
+	blkptr_t *bp_orig = &zio->io_bp_orig;
+	objset_t *os = arg;
 
 	if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
-		ASSERT(DVA_EQUAL(BP_IDENTITY(bp), BP_IDENTITY(bp_orig)));
+		ASSERT(BP_EQUAL(bp, bp_orig));
 	} else {
-		if (zio->io_bp_orig.blk_birth == os->os_synctx->tx_txg)
-			(void) dsl_dataset_block_kill(os->os_dsl_dataset,
-			    &zio->io_bp_orig, zio, os->os_synctx);
-		dsl_dataset_block_born(os->os_dsl_dataset, bp, os->os_synctx);
+		dsl_dataset_t *ds = os->os_dsl_dataset;
+		dmu_tx_t *tx = os->os_synctx;
+
+		(void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
+		dsl_dataset_block_born(ds, bp, tx);
 	}
 }
 
 /* called from dsl */
 void
-dmu_objset_sync(objset_impl_t *os, zio_t *pio, dmu_tx_t *tx)
+dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
 {
 	int txgoff;
 	zbookmark_t zb;
-	writeprops_t wp = { 0 };
+	zio_prop_t zp;
 	zio_t *zio;
 	list_t *list;
 	list_t *newlist = NULL;
@@ -949,26 +1019,17 @@ dmu_objset_sync(objset_impl_t *os, zio_t *pio, dmu_tx_t *tx)
 	/*
 	 * Create the root block IO
 	 */
-	zb.zb_objset = os->os_dsl_dataset ? os->os_dsl_dataset->ds_object : 0;
-	zb.zb_object = 0;
-	zb.zb_level = -1;	/* for block ordering; it's level 0 on disk */
-	zb.zb_blkid = 0;
-
-	wp.wp_type = DMU_OT_OBJSET;
-	wp.wp_level = 0;	/* on-disk BP level; see above */
-	wp.wp_copies = os->os_copies;
-	wp.wp_oschecksum = os->os_checksum;
-	wp.wp_oscompress = os->os_compress;
-
-	if (BP_IS_OLDER(os->os_rootbp, tx->tx_txg)) {
-		(void) dsl_dataset_block_kill(os->os_dsl_dataset,
-		    os->os_rootbp, pio, tx);
-	}
+	SET_BOOKMARK(&zb, os->os_dsl_dataset ?
+	    os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
+	    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
+	VERIFY3U(0, ==, arc_release_bp(os->os_phys_buf, &os->os_phys_buf,
+	    os->os_rootbp, os->os_spa, &zb));
 
-	arc_release(os->os_phys_buf, &os->os_phys_buf);
+	dmu_write_policy(os, NULL, 0, 0, &zp);
 
-	zio = arc_write(pio, os->os_spa, &wp, DMU_OS_IS_L2CACHEABLE(os),
-	    tx->tx_txg, os->os_rootbp, os->os_phys_buf, ready, NULL, os,
+	zio = arc_write(pio, os->os_spa, tx->tx_txg,
+	    os->os_rootbp, os->os_phys_buf, DMU_OS_IS_L2CACHEABLE(os), &zp,
+	    dmu_objset_write_ready, dmu_objset_write_done, os,
 	    ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
 
 	/*
@@ -1017,7 +1078,14 @@ dmu_objset_sync(objset_impl_t *os, zio_t *pio, dmu_tx_t *tx)
 	zio_nowait(zio);
 }
 
-static objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
+boolean_t
+dmu_objset_is_dirty(objset_t *os, uint64_t txg)
+{
+	return (!list_is_empty(&os->os_dirty_dnodes[txg & TXG_MASK]) ||
+	    !list_is_empty(&os->os_free_dnodes[txg & TXG_MASK]));
+}
+
+objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
 
 void
 dmu_objset_register_type(dmu_objset_type_t ost, objset_used_cb_t *cb)
@@ -1026,74 +1094,84 @@ dmu_objset_register_type(dmu_objset_type_t ost, objset_used_cb_t *cb)
 }
 
 boolean_t
-dmu_objset_userused_enabled(objset_impl_t *os)
+dmu_objset_userused_enabled(objset_t *os)
 {
 	return (spa_version(os->os_spa) >= SPA_VERSION_USERSPACE &&
 	    used_cbs[os->os_phys->os_type] &&
 	    os->os_userused_dnode);
 }
 
+static void
+do_userquota_update(objset_t *os, uint64_t used, uint64_t flags,
+    uint64_t user, uint64_t group, boolean_t subtract, dmu_tx_t *tx)
+{
+	if ((flags & DNODE_FLAG_USERUSED_ACCOUNTED)) {
+		int64_t delta = DNODE_SIZE + used;
+		if (subtract)
+			delta = -delta;
+		VERIFY3U(0, ==, zap_increment_int(os, DMU_USERUSED_OBJECT,
+		    user, delta, tx));
+		VERIFY3U(0, ==, zap_increment_int(os, DMU_GROUPUSED_OBJECT,
+		    group, delta, tx));
+	}
+}
+
 void
-dmu_objset_do_userquota_callbacks(objset_impl_t *os, dmu_tx_t *tx)
+dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
 {
 	dnode_t *dn;
 	list_t *list = &os->os_synced_dnodes;
-	static const char zerobuf[DN_MAX_BONUSLEN] = {0};
 
 	ASSERT(list_head(list) == NULL || dmu_objset_userused_enabled(os));
 
 	while (dn = list_head(list)) {
-		dmu_object_type_t bonustype;
-
 		ASSERT(!DMU_OBJECT_IS_SPECIAL(dn->dn_object));
-		ASSERT(dn->dn_oldphys);
 		ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE ||
 		    dn->dn_phys->dn_flags &
 		    DNODE_FLAG_USERUSED_ACCOUNTED);
 
 		/* Allocate the user/groupused objects if necessary. */
 		if (os->os_userused_dnode->dn_type == DMU_OT_NONE) {
-			VERIFY(0 == zap_create_claim(&os->os,
+			VERIFY(0 == zap_create_claim(os,
 			    DMU_USERUSED_OBJECT,
 			    DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
-			VERIFY(0 == zap_create_claim(&os->os,
+			VERIFY(0 == zap_create_claim(os,
 			    DMU_GROUPUSED_OBJECT,
 			    DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
 		}
 
 		/*
-		 * If the object was not previously
-		 * accounted, pretend that it was free.
+		 * We intentionally modify the zap object even if the
+		 * net delta is zero.  Otherwise
+		 * the block of the zap obj could be shared between
+		 * datasets but need to be different between them after
+		 * a bprewrite.
 		 */
-		if (!(dn->dn_oldphys->dn_flags &
-		    DNODE_FLAG_USERUSED_ACCOUNTED)) {
-			bzero(dn->dn_oldphys, sizeof (dnode_phys_t));
-		}
-
-		/*
-		 * If the object was freed, use the previous bonustype.
-		 */
-		bonustype = dn->dn_phys->dn_bonustype ?
-		    dn->dn_phys->dn_bonustype : dn->dn_oldphys->dn_bonustype;
-		ASSERT(dn->dn_phys->dn_type != 0 ||
-		    (bcmp(DN_BONUS(dn->dn_phys), zerobuf,
-		    DN_MAX_BONUSLEN) == 0 &&
-		    DN_USED_BYTES(dn->dn_phys) == 0));
-		ASSERT(dn->dn_oldphys->dn_type != 0 ||
-		    (bcmp(DN_BONUS(dn->dn_oldphys), zerobuf,
-		    DN_MAX_BONUSLEN) == 0 &&
-		    DN_USED_BYTES(dn->dn_oldphys) == 0));
-		used_cbs[os->os_phys->os_type](&os->os, bonustype,
-		    DN_BONUS(dn->dn_oldphys), DN_BONUS(dn->dn_phys),
-		    DN_USED_BYTES(dn->dn_oldphys),
-		    DN_USED_BYTES(dn->dn_phys), tx);
 
-		/*
-		 * The mutex is needed here for interlock with dnode_allocate.
-		 */
 		mutex_enter(&dn->dn_mtx);
-		zio_buf_free(dn->dn_oldphys, sizeof (dnode_phys_t));
-		dn->dn_oldphys = NULL;
+		ASSERT(dn->dn_id_flags);
+		if (dn->dn_id_flags & DN_ID_OLD_EXIST)  {
+			do_userquota_update(os, dn->dn_oldused, dn->dn_oldflags,
+			    dn->dn_olduid, dn->dn_oldgid, B_TRUE, tx);
+		}
+		if (dn->dn_id_flags & DN_ID_NEW_EXIST) {
+			do_userquota_update(os, DN_USED_BYTES(dn->dn_phys),
+			    dn->dn_phys->dn_flags,  dn->dn_newuid,
+			    dn->dn_newgid, B_FALSE, tx);
+		}
+
+		dn->dn_oldused = 0;
+		dn->dn_oldflags = 0;
+		if (dn->dn_id_flags & DN_ID_NEW_EXIST) {
+			dn->dn_olduid = dn->dn_newuid;
+			dn->dn_oldgid = dn->dn_newgid;
+			dn->dn_id_flags |= DN_ID_OLD_EXIST;
+			if (dn->dn_bonuslen == 0)
+				dn->dn_id_flags |= DN_ID_CHKED_SPILL;
+			else
+				dn->dn_id_flags |= DN_ID_CHKED_BONUS;
+		}
+		dn->dn_id_flags &= ~(DN_ID_NEW_EXIST);
 		mutex_exit(&dn->dn_mtx);
 
 		list_remove(list, dn);
@@ -1101,10 +1179,140 @@ dmu_objset_do_userquota_callbacks(objset_impl_t *os, dmu_tx_t *tx)
 	}
 }
 
+/*
+ * Returns a pointer to data to find uid/gid from
+ *
+ * If a dirty record for transaction group that is syncing can't
+ * be found then NULL is returned.  In the NULL case it is assumed
+ * the uid/gid aren't changing.
+ */
+static void *
+dmu_objset_userquota_find_data(dmu_buf_impl_t *db, dmu_tx_t *tx)
+{
+	dbuf_dirty_record_t *dr, **drp;
+	void *data;
+
+	if (db->db_dirtycnt == 0)
+		return (db->db.db_data);  /* Nothing is changing */
+
+	for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
+		if (dr->dr_txg == tx->tx_txg)
+			break;
+
+	if (dr == NULL)
+		data = NULL;
+	else if (dr->dr_dbuf->db_dnode->dn_bonuslen == 0 &&
+	    dr->dr_dbuf->db_blkid == DMU_SPILL_BLKID)
+		data = dr->dt.dl.dr_data->b_data;
+	else
+		data = dr->dt.dl.dr_data;
+	return (data);
+}
+
+void
+dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx)
+{
+	objset_t *os = dn->dn_objset;
+	void *data = NULL;
+	dmu_buf_impl_t *db = NULL;
+	uint64_t *user, *group;
+	int flags = dn->dn_id_flags;
+	int error;
+	boolean_t have_spill = B_FALSE;
+
+	if (!dmu_objset_userused_enabled(dn->dn_objset))
+		return;
+
+	if (before && (flags & (DN_ID_CHKED_BONUS|DN_ID_OLD_EXIST|
+	    DN_ID_CHKED_SPILL)))
+		return;
+
+	if (before && dn->dn_bonuslen != 0)
+		data = DN_BONUS(dn->dn_phys);
+	else if (!before && dn->dn_bonuslen != 0) {
+		if (dn->dn_bonus) {
+			db = dn->dn_bonus;
+			mutex_enter(&db->db_mtx);
+			data = dmu_objset_userquota_find_data(db, tx);
+		} else {
+			data = DN_BONUS(dn->dn_phys);
+		}
+	} else if (dn->dn_bonuslen == 0 && dn->dn_bonustype == DMU_OT_SA) {
+			int rf = 0;
+
+			if (RW_WRITE_HELD(&dn->dn_struct_rwlock))
+				rf |= DB_RF_HAVESTRUCT;
+			error = dmu_spill_hold_by_dnode(dn, rf,
+			    FTAG, (dmu_buf_t **)&db);
+			ASSERT(error == 0);
+			mutex_enter(&db->db_mtx);
+			data = (before) ? db->db.db_data :
+			    dmu_objset_userquota_find_data(db, tx);
+			have_spill = B_TRUE;
+	} else {
+		mutex_enter(&dn->dn_mtx);
+		dn->dn_id_flags |= DN_ID_CHKED_BONUS;
+		mutex_exit(&dn->dn_mtx);
+		return;
+	}
+
+	if (before) {
+		ASSERT(data);
+		user = &dn->dn_olduid;
+		group = &dn->dn_oldgid;
+	} else if (data) {
+		user = &dn->dn_newuid;
+		group = &dn->dn_newgid;
+	}
+
+	/*
+	 * Must always call the callback in case the object
+	 * type has changed and that type isn't an object type to track
+	 */
+	error = used_cbs[os->os_phys->os_type](dn->dn_bonustype, data,
+	    user, group);
+
+	/*
+	 * Preserve existing uid/gid when the callback can't determine
+	 * what the new uid/gid are and the callback returned EEXIST.
+	 * The EEXIST error tells us to just use the existing uid/gid.
+	 * If we don't know what the old values are then just assign
+	 * them to 0, since that is a new file  being created.
+	 */
+	if (!before && data == NULL && error == EEXIST) {
+		if (flags & DN_ID_OLD_EXIST) {
+			dn->dn_newuid = dn->dn_olduid;
+			dn->dn_newgid = dn->dn_oldgid;
+		} else {
+			dn->dn_newuid = 0;
+			dn->dn_newgid = 0;
+		}
+		error = 0;
+	}
+
+	if (db)
+		mutex_exit(&db->db_mtx);
+
+	mutex_enter(&dn->dn_mtx);
+	if (error == 0 && before)
+		dn->dn_id_flags |= DN_ID_OLD_EXIST;
+	if (error == 0 && !before)
+		dn->dn_id_flags |= DN_ID_NEW_EXIST;
+
+	if (have_spill) {
+		dn->dn_id_flags |= DN_ID_CHKED_SPILL;
+	} else {
+		dn->dn_id_flags |= DN_ID_CHKED_BONUS;
+	}
+	mutex_exit(&dn->dn_mtx);
+	if (have_spill)
+		dmu_buf_rele((dmu_buf_t *)db, FTAG);
+}
+
 boolean_t
 dmu_objset_userspace_present(objset_t *os)
 {
-	return (os->os->os_phys->os_flags &
+	return (os->os_phys->os_flags &
 	    OBJSET_FLAG_USERACCOUNTING_COMPLETE);
 }
 
@@ -1116,7 +1324,7 @@ dmu_objset_userspace_upgrade(objset_t *os)
 
 	if (dmu_objset_userspace_present(os))
 		return (0);
-	if (!dmu_objset_userused_enabled(os->os))
+	if (!dmu_objset_userused_enabled(os))
 		return (ENOTSUP);
 	if (dmu_objset_is_snapshot(os))
 		return (EINVAL);
@@ -1152,7 +1360,7 @@ dmu_objset_userspace_upgrade(objset_t *os)
 		dmu_tx_commit(tx);
 	}
 
-	os->os->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
+	os->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
 	txg_wait_synced(dmu_objset_pool(os), 0);
 	return (0);
 }
@@ -1161,35 +1369,35 @@ void
 dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
     uint64_t *usedobjsp, uint64_t *availobjsp)
 {
-	dsl_dataset_space(os->os->os_dsl_dataset, refdbytesp, availbytesp,
+	dsl_dataset_space(os->os_dsl_dataset, refdbytesp, availbytesp,
 	    usedobjsp, availobjsp);
 }
 
 uint64_t
 dmu_objset_fsid_guid(objset_t *os)
 {
-	return (dsl_dataset_fsid_guid(os->os->os_dsl_dataset));
+	return (dsl_dataset_fsid_guid(os->os_dsl_dataset));
 }
 
 void
 dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat)
 {
-	stat->dds_type = os->os->os_phys->os_type;
-	if (os->os->os_dsl_dataset)
-		dsl_dataset_fast_stat(os->os->os_dsl_dataset, stat);
+	stat->dds_type = os->os_phys->os_type;
+	if (os->os_dsl_dataset)
+		dsl_dataset_fast_stat(os->os_dsl_dataset, stat);
 }
 
 void
 dmu_objset_stats(objset_t *os, nvlist_t *nv)
 {
-	ASSERT(os->os->os_dsl_dataset ||
-	    os->os->os_phys->os_type == DMU_OST_META);
+	ASSERT(os->os_dsl_dataset ||
+	    os->os_phys->os_type == DMU_OST_META);
 
-	if (os->os->os_dsl_dataset != NULL)
-		dsl_dataset_stats(os->os->os_dsl_dataset, nv);
+	if (os->os_dsl_dataset != NULL)
+		dsl_dataset_stats(os->os_dsl_dataset, nv);
 
 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_TYPE,
-	    os->os->os_phys->os_type);
+	    os->os_phys->os_type);
 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERACCOUNTING,
 	    dmu_objset_userspace_present(os));
 }
@@ -1197,8 +1405,8 @@ dmu_objset_stats(objset_t *os, nvlist_t *nv)
 int
 dmu_objset_is_snapshot(objset_t *os)
 {
-	if (os->os->os_dsl_dataset != NULL)
-		return (dsl_dataset_is_snapshot(os->os->os_dsl_dataset));
+	if (os->os_dsl_dataset != NULL)
+		return (dsl_dataset_is_snapshot(os->os_dsl_dataset));
 	else
 		return (B_FALSE);
 }
@@ -1207,7 +1415,7 @@ int
 dmu_snapshot_realname(objset_t *os, char *name, char *real, int maxlen,
     boolean_t *conflict)
 {
-	dsl_dataset_t *ds = os->os->os_dsl_dataset;
+	dsl_dataset_t *ds = os->os_dsl_dataset;
 	uint64_t ignored;
 
 	if (ds->ds_phys->ds_snapnames_zapobj == 0)
@@ -1222,7 +1430,7 @@ int
 dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
     uint64_t *idp, uint64_t *offp, boolean_t *case_conflict)
 {
-	dsl_dataset_t *ds = os->os->os_dsl_dataset;
+	dsl_dataset_t *ds = os->os_dsl_dataset;
 	zap_cursor_t cursor;
 	zap_attribute_t attr;
 
@@ -1259,12 +1467,12 @@ int
 dmu_dir_list_next(objset_t *os, int namelen, char *name,
     uint64_t *idp, uint64_t *offp)
 {
-	dsl_dir_t *dd = os->os->os_dsl_dataset->ds_dir;
+	dsl_dir_t *dd = os->os_dsl_dataset->ds_dir;
 	zap_cursor_t cursor;
 	zap_attribute_t attr;
 
 	/* there is no next dir on a snapshot! */
-	if (os->os->os_dsl_dataset->ds_object !=
+	if (os->os_dsl_dataset->ds_object !=
 	    dd->dd_phys->dd_head_dataset_obj)
 		return (ENOENT);
 
@@ -1293,7 +1501,7 @@ dmu_dir_list_next(objset_t *os, int namelen, char *name,
 }
 
 struct findarg {
-	int (*func)(char *, void *);
+	int (*func)(const char *, void *);
 	void *arg;
 };
 
@@ -1302,7 +1510,7 @@ static int
 findfunc(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
 {
 	struct findarg *fa = arg;
-	return (fa->func((char *)dsname, fa->arg));
+	return (fa->func(dsname, fa->arg));
 }
 
 /*
@@ -1310,7 +1518,8 @@ findfunc(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
  * Perhaps change all callers to use dmu_objset_find_spa()?
  */
 int
-dmu_objset_find(char *name, int func(char *, void *), void *arg, int flags)
+dmu_objset_find(char *name, int func(const char *, void *), void *arg,
+    int flags)
 {
 	struct findarg fa;
 	fa.func = func;
@@ -1361,12 +1570,9 @@ dmu_objset_find_spa(spa_t *spa, const char *name,
 			ASSERT(attr->za_integer_length == sizeof (uint64_t));
 			ASSERT(attr->za_num_integers == 1);
 
-			child = kmem_alloc(MAXPATHLEN, KM_SLEEP);
-			(void) strcpy(child, name);
-			(void) strcat(child, "/");
-			(void) strcat(child, attr->za_name);
+			child = kmem_asprintf("%s/%s", name, attr->za_name);
 			err = dmu_objset_find_spa(spa, child, func, arg, flags);
-			kmem_free(child, MAXPATHLEN);
+			strfree(child);
 			if (err)
 				break;
 		}
@@ -1400,13 +1606,11 @@ dmu_objset_find_spa(spa_t *spa, const char *name,
 				    sizeof (uint64_t));
 				ASSERT(attr->za_num_integers == 1);
 
-				child = kmem_alloc(MAXPATHLEN, KM_SLEEP);
-				(void) strcpy(child, name);
-				(void) strcat(child, "@");
-				(void) strcat(child, attr->za_name);
+				child = kmem_asprintf("%s@%s",
+				    name, attr->za_name);
 				err = func(spa, attr->za_first_integer,
 				    child, arg);
-				kmem_free(child, MAXPATHLEN);
+				strfree(child);
 				if (err)
 					break;
 			}
@@ -1429,7 +1633,7 @@ dmu_objset_find_spa(spa_t *spa, const char *name,
 
 /* ARGSUSED */
 int
-dmu_objset_prefetch(char *name, void *arg)
+dmu_objset_prefetch(const char *name, void *arg)
 {
 	dsl_dataset_t *ds;
 
@@ -1438,16 +1642,14 @@ dmu_objset_prefetch(char *name, void *arg)
 
 	if (!BP_IS_HOLE(&ds->ds_phys->ds_bp)) {
 		mutex_enter(&ds->ds_opening_lock);
-		if (!dsl_dataset_get_user_ptr(ds)) {
+		if (ds->ds_objset == NULL) {
 			uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
 			zbookmark_t zb;
 
-			zb.zb_objset = ds->ds_object;
-			zb.zb_object = 0;
-			zb.zb_level = -1;
-			zb.zb_blkid = 0;
+			SET_BOOKMARK(&zb, ds->ds_object, ZB_ROOT_OBJECT,
+			    ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 
-			(void) arc_read_nolock(NULL, dsl_dataset_get_spa(ds),
+			(void) dsl_read_nolock(NULL, dsl_dataset_get_spa(ds),
 			    &ds->ds_phys->ds_bp, NULL, NULL,
 			    ZIO_PRIORITY_ASYNC_READ,
 			    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
@@ -1463,13 +1665,13 @@ dmu_objset_prefetch(char *name, void *arg)
 void
 dmu_objset_set_user(objset_t *os, void *user_ptr)
 {
-	ASSERT(MUTEX_HELD(&os->os->os_user_ptr_lock));
-	os->os->os_user_ptr = user_ptr;
+	ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
+	os->os_user_ptr = user_ptr;
 }
 
 void *
 dmu_objset_get_user(objset_t *os)
 {
-	ASSERT(MUTEX_HELD(&os->os->os_user_ptr_lock));
-	return (os->os->os_user_ptr);
+	ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
+	return (os->os_user_ptr);
 }