Merge commit 'refs/top-bases/fix-pthreads' into fix-pthreads

1 files changed, 1228 insertions, 0 deletions

diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c
new file mode 100644
index 000000000..7981e0682
--- /dev/null
+++ b/module/zfs/dmu_objset.c
@@ -0,0 +1,1228 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <sys/cred.h>
+#include <sys/zfs_context.h>
+#include <sys/dmu_objset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_prop.h>
+#include <sys/dsl_pool.h>
+#include <sys/dsl_synctask.h>
+#include <sys/dsl_deleg.h>
+#include <sys/dnode.h>
+#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>
+
+spa_t *
+dmu_objset_spa(objset_t *os)
+{
+	return (os->os->os_spa);
+}
+
+zilog_t *
+dmu_objset_zil(objset_t *os)
+{
+	return (os->os->os_zil);
+}
+
+dsl_pool_t *
+dmu_objset_pool(objset_t *os)
+{
+	dsl_dataset_t *ds;
+
+	if ((ds = os->os->os_dsl_dataset) != NULL && ds->ds_dir)
+		return (ds->ds_dir->dd_pool);
+	else
+		return (spa_get_dsl(os->os->os_spa));
+}
+
+dsl_dataset_t *
+dmu_objset_ds(objset_t *os)
+{
+	return (os->os->os_dsl_dataset);
+}
+
+dmu_objset_type_t
+dmu_objset_type(objset_t *os)
+{
+	return (os->os->os_phys->os_type);
+}
+
+void
+dmu_objset_name(objset_t *os, char *buf)
+{
+	dsl_dataset_name(os->os->os_dsl_dataset, buf);
+}
+
+uint64_t
+dmu_objset_id(objset_t *os)
+{
+	dsl_dataset_t *ds = os->os->os_dsl_dataset;
+
+	return (ds ? ds->ds_object : 0);
+}
+
+static void
+checksum_changed_cb(void *arg, uint64_t newval)
+{
+	objset_impl_t *osi = arg;
+
+	/*
+	 * Inheritance should have been done by now.
+	 */
+	ASSERT(newval != ZIO_CHECKSUM_INHERIT);
+
+	osi->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;
+
+	/*
+	 * 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);
+}
+
+static void
+copies_changed_cb(void *arg, uint64_t newval)
+{
+	objset_impl_t *osi = arg;
+
+	/*
+	 * Inheritance and range checking should have been done by now.
+	 */
+	ASSERT(newval > 0);
+	ASSERT(newval <= spa_max_replication(osi->os_spa));
+
+	osi->os_copies = newval;
+}
+
+static void
+primary_cache_changed_cb(void *arg, uint64_t newval)
+{
+	objset_impl_t *osi = arg;
+
+	/*
+	 * Inheritance and range checking should have been done by now.
+	 */
+	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
+	    newval == ZFS_CACHE_METADATA);
+
+	osi->os_primary_cache = newval;
+}
+
+static void
+secondary_cache_changed_cb(void *arg, uint64_t newval)
+{
+	objset_impl_t *osi = arg;
+
+	/*
+	 * Inheritance and range checking should have been done by now.
+	 */
+	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
+	    newval == ZFS_CACHE_METADATA);
+
+	osi->os_secondary_cache = newval;
+}
+
+void
+dmu_objset_byteswap(void *buf, size_t size)
+{
+	objset_phys_t *osp = buf;
+
+	ASSERT(size == sizeof (objset_phys_t));
+	dnode_byteswap(&osp->os_meta_dnode);
+	byteswap_uint64_array(&osp->os_zil_header, sizeof (zil_header_t));
+	osp->os_type = BSWAP_64(osp->os_type);
+}
+
+int
+dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
+    objset_impl_t **osip)
+{
+	objset_impl_t *osi;
+	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)) {
+		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))
+			aflags |= ARC_L2CACHE;
+
+		dprintf_bp(osi->os_rootbp, "reading %s", "");
+		/*
+		 * NB: 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,
+		    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &aflags, &zb);
+		if (err) {
+			kmem_free(osi, sizeof (objset_impl_t));
+			/* convert checksum errors into IO errors */
+			if (err == ECKSUM)
+				err = EIO;
+			return (err);
+		}
+		osi->os_phys = osi->os_phys_buf->b_data;
+	} else {
+		osi->os_phys_buf = arc_buf_alloc(spa, sizeof (objset_phys_t),
+		    &osi->os_phys_buf, ARC_BUFC_METADATA);
+		osi->os_phys = osi->os_phys_buf->b_data;
+		bzero(osi->os_phys, sizeof (objset_phys_t));
+	}
+
+	/*
+	 * Note: the changed_cb will be called once before the register
+	 * func returns, thus changing the checksum/compression from the
+	 * default (fletcher2/off).  Snapshots don't need to know about
+	 * checksum/compression/copies.
+	 */
+	if (ds) {
+		err = dsl_prop_register(ds, "primarycache",
+		    primary_cache_changed_cb, osi);
+		if (err == 0)
+			err = dsl_prop_register(ds, "secondarycache",
+			    secondary_cache_changed_cb, osi);
+		if (!dsl_dataset_is_snapshot(ds)) {
+			if (err == 0)
+				err = dsl_prop_register(ds, "checksum",
+				    checksum_changed_cb, osi);
+			if (err == 0)
+				err = dsl_prop_register(ds, "compression",
+				    compression_changed_cb, osi);
+			if (err == 0)
+				err = dsl_prop_register(ds, "copies",
+				    copies_changed_cb, osi);
+		}
+		if (err) {
+			VERIFY(arc_buf_remove_ref(osi->os_phys_buf,
+			    &osi->os_phys_buf) == 1);
+			kmem_free(osi, sizeof (objset_impl_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;
+	}
+
+	osi->os_zil_header = osi->os_phys->os_zil_header;
+	osi->os_zil = zil_alloc(&osi->os, &osi->os_zil_header);
+
+	for (i = 0; i < TXG_SIZE; i++) {
+		list_create(&osi->os_dirty_dnodes[i], sizeof (dnode_t),
+		    offsetof(dnode_t, dn_dirty_link[i]));
+		list_create(&osi->os_free_dnodes[i], sizeof (dnode_t),
+		    offsetof(dnode_t, dn_dirty_link[i]));
+	}
+	list_create(&osi->os_dnodes, sizeof (dnode_t),
+	    offsetof(dnode_t, dn_link));
+	list_create(&osi->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);
+
+	/*
+	 * We should be the only thread trying to do this because we
+	 * have ds_opening_lock
+	 */
+	if (ds) {
+		VERIFY(NULL == dsl_dataset_set_user_ptr(ds, osi,
+		    dmu_objset_evict));
+	}
+
+	*osip = osi;
+	return (0);
+}
+
+static int
+dmu_objset_open_ds_os(dsl_dataset_t *ds, objset_t *os, dmu_objset_type_t type)
+{
+	objset_impl_t *osi;
+
+	mutex_enter(&ds->ds_opening_lock);
+	osi = dsl_dataset_get_user_ptr(ds);
+	if (osi == NULL) {
+		int err;
+
+		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);
+		}
+	}
+	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);
+}
+
+int
+dmu_objset_open_ds(dsl_dataset_t *ds, dmu_objset_type_t type, objset_t **osp)
+{
+	objset_t *os;
+	int err;
+
+	os = kmem_alloc(sizeof (objset_t), KM_SLEEP);
+	err = dmu_objset_open_ds_os(ds, os, type);
+	if (err)
+		kmem_free(os, sizeof (objset_t));
+	else
+		*osp = os;
+	return (err);
+}
+
+/* called from zpl */
+int
+dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
+    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));
+		return (err);
+	}
+
+	err = dmu_objset_open_ds_os(ds, os, type);
+	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;
+	}
+	return (err);
+}
+
+void
+dmu_objset_close(objset_t *os)
+{
+	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);
+
+	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));
+}
+
+int
+dmu_objset_evict_dbufs(objset_t *os)
+{
+	objset_impl_t *osi = os->os;
+	dnode_t *dn;
+
+	mutex_enter(&osi->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);
+
+	/*
+	 * Find the first dnode with holds.  We have to do this dance
+	 * because dnode_add_ref() only works if you already have a
+	 * hold.  If there are no holds then it has no dbufs so OK to
+	 * skip.
+	 */
+	for (dn = list_head(&osi->os_dnodes);
+	    dn && !dnode_add_ref(dn, FTAG);
+	    dn = list_next(&osi->os_dnodes, dn))
+		continue;
+
+	while (dn) {
+		dnode_t *next_dn = dn;
+
+		do {
+			next_dn = list_next(&osi->os_dnodes, next_dn);
+		} while (next_dn && !dnode_add_ref(next_dn, FTAG));
+
+		mutex_exit(&osi->os_lock);
+		dnode_evict_dbufs(dn);
+		dnode_rele(dn, FTAG);
+		mutex_enter(&osi->os_lock);
+		dn = next_dn;
+	}
+	mutex_exit(&osi->os_lock);
+	return (list_head(&osi->os_dnodes) != osi->os_meta_dnode);
+}
+
+void
+dmu_objset_evict(dsl_dataset_t *ds, void *arg)
+{
+	objset_impl_t *osi = arg;
+	objset_t os;
+	int i;
+
+	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);
+	}
+
+	if (ds) {
+		if (!dsl_dataset_is_snapshot(ds)) {
+			VERIFY(0 == dsl_prop_unregister(ds, "checksum",
+			    checksum_changed_cb, osi));
+			VERIFY(0 == dsl_prop_unregister(ds, "compression",
+			    compression_changed_cb, osi));
+			VERIFY(0 == dsl_prop_unregister(ds, "copies",
+			    copies_changed_cb, osi));
+		}
+		VERIFY(0 == dsl_prop_unregister(ds, "primarycache",
+		    primary_cache_changed_cb, osi));
+		VERIFY(0 == dsl_prop_unregister(ds, "secondarycache",
+		    secondary_cache_changed_cb, osi));
+	}
+
+	/*
+	 * 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);
+
+	ASSERT3P(list_head(&osi->os_dnodes), ==, osi->os_meta_dnode);
+	ASSERT3P(list_tail(&osi->os_dnodes), ==, osi->os_meta_dnode);
+	ASSERT3P(list_head(&osi->os_meta_dnode->dn_dbufs), ==, NULL);
+
+	dnode_special_close(osi->os_meta_dnode);
+	zil_free(osi->os_zil);
+
+	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));
+}
+
+/* called from dsl for meta-objset */
+objset_impl_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;
+	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));
+	if (ds)
+		mutex_exit(&ds->ds_opening_lock);
+	mdn = osi->os_meta_dnode;
+
+	dnode_allocate(mdn, DMU_OT_DNODE, 1 << DNODE_BLOCK_SHIFT,
+	    DN_MAX_INDBLKSHIFT, DMU_OT_NONE, 0, tx);
+
+	/*
+	 * We don't want to have to increase the meta-dnode's nlevels
+	 * later, because then we could do it in quescing context while
+	 * we are also accessing it in open context.
+	 *
+	 * This precaution is not necessary for the MOS (ds == NULL),
+	 * because the MOS is only updated in syncing context.
+	 * This is most fortunate: the MOS is the only objset that
+	 * needs to be synced multiple times as spa_sync() iterates
+	 * to convergence, so minimizing its dn_nlevels matters.
+	 */
+	if (ds != NULL) {
+		int levels = 1;
+
+		/*
+		 * Determine the number of levels necessary for the meta-dnode
+		 * to contain DN_MAX_OBJECT dnodes.
+		 */
+		while ((uint64_t)mdn->dn_nblkptr << (mdn->dn_datablkshift +
+		    (levels - 1) * (mdn->dn_indblkshift - SPA_BLKPTRSHIFT)) <
+		    DN_MAX_OBJECT * sizeof (dnode_phys_t))
+			levels++;
+
+		mdn->dn_next_nlevels[tx->tx_txg & TXG_MASK] =
+		    mdn->dn_nlevels = levels;
+	}
+
+	ASSERT(type != DMU_OST_NONE);
+	ASSERT(type != DMU_OST_ANY);
+	ASSERT(type < DMU_OST_NUMTYPES);
+	osi->os_phys->os_type = type;
+
+	dsl_dataset_dirty(ds, tx);
+
+	return (osi);
+}
+
+struct oscarg {
+	void (*userfunc)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
+	void *userarg;
+	dsl_dataset_t *clone_parent;
+	const char *lastname;
+	dmu_objset_type_t type;
+	uint64_t flags;
+};
+
+/*ARGSUSED*/
+static int
+dmu_objset_create_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	dsl_dir_t *dd = arg1;
+	struct oscarg *oa = arg2;
+	objset_t *mos = dd->dd_pool->dp_meta_objset;
+	int err;
+	uint64_t ddobj;
+
+	err = zap_lookup(mos, dd->dd_phys->dd_child_dir_zapobj,
+	    oa->lastname, sizeof (uint64_t), 1, &ddobj);
+	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)
+			return (EXDEV);
+
+		/*
+		 * You can only clone snapshots, not the head datasets.
+		 */
+		if (oa->clone_parent->ds_phys->ds_num_children == 0)
+			return (EINVAL);
+	}
+
+	return (0);
+}
+
+static void
+dmu_objset_create_sync(void *arg1, void *arg2, cred_t *cr, 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);
+
+	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;
+
+		/* This is an empty dmu_objset; not a clone. */
+		osi = 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);
+	}
+
+	spa_history_internal_log(LOG_DS_CREATE, dd->dd_pool->dp_spa,
+	    tx, cr, "dataset = %llu", dsobj);
+
+	dsl_dataset_rele(ds, FTAG);
+}
+
+int
+dmu_objset_create(const char *name, dmu_objset_type_t type,
+    objset_t *clone_parent, uint64_t flags,
+    void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg)
+{
+	dsl_dir_t *pdd;
+	const char *tail;
+	int err = 0;
+	struct oscarg oa = { 0 };
+
+	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);
+	}
+
+	dprintf("name=%s\n", name);
+
+	oa.userfunc = func;
+	oa.userarg = arg;
+	oa.lastname = tail;
+	oa.type = type;
+	oa.flags = flags;
+
+	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);
+	return (err);
+}
+
+int
+dmu_objset_destroy(const char *name)
+{
+	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);
+
+		error = dsl_dataset_destroy(ds, os);
+		/*
+		 * dsl_dataset_destroy() closes the ds.
+		 */
+		kmem_free(os, sizeof (objset_t));
+	}
+
+	return (error);
+}
+
+/*
+ * This will close the objset.
+ */
+int
+dmu_objset_rollback(objset_t *os)
+{
+	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);
+
+	/*
+	 * NB: we close the objset manually because the rollback
+	 * actually implicitly called dmu_objset_evict(), thus freeing
+	 * the objset_impl_t.
+	 */
+	dsl_dataset_disown(ds, os);
+	kmem_free(os, sizeof (objset_t));
+	return (err);
+}
+
+struct snaparg {
+	dsl_sync_task_group_t *dstg;
+	char *snapname;
+	char failed[MAXPATHLEN];
+	boolean_t checkperms;
+	list_t objsets;
+};
+
+struct osnode {
+	list_node_t node;
+	objset_t *os;
+};
+
+static int
+dmu_objset_snapshot_one(char *name, void *arg)
+{
+	struct snaparg *sn = arg;
+	objset_t *os;
+	int err;
+
+	(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()
+	 */
+	if (sn->checkperms == B_TRUE &&
+	    (err = zfs_secpolicy_snapshot_perms(name, CRED())))
+		return (err);
+
+	err = dmu_objset_open(name, DMU_OST_ANY, DS_MODE_USER, &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);
+	}
+
+	/*
+	 * NB: we need to wait for all in-flight changes to get to disk,
+	 * so that we snapshot those changes.  zil_suspend does this as
+	 * a side effect.
+	 */
+	err = zil_suspend(dmu_objset_zil(os));
+	if (err == 0) {
+		struct osnode *osn;
+		dsl_sync_task_create(sn->dstg, dsl_dataset_snapshot_check,
+		    dsl_dataset_snapshot_sync, os->os->os_dsl_dataset,
+		    sn->snapname, 3);
+		osn = kmem_alloc(sizeof (struct osnode), KM_SLEEP);
+		osn->os = os;
+		list_insert_tail(&sn->objsets, osn);
+	} else {
+		dmu_objset_close(os);
+	}
+
+	return (err);
+}
+
+int
+dmu_objset_snapshot(char *fsname, char *snapname, boolean_t recursive)
+{
+	dsl_sync_task_t *dst;
+	struct osnode *osn;
+	struct snaparg sn = { 0 };
+	spa_t *spa;
+	int err;
+
+	(void) strcpy(sn.failed, fsname);
+
+	err = spa_open(fsname, &spa, FTAG);
+	if (err)
+		return (err);
+
+	sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
+	sn.snapname = snapname;
+	list_create(&sn.objsets, sizeof (struct osnode),
+	    offsetof(struct osnode, node));
+
+	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);
+	}
+
+	if (err)
+		goto out;
+
+	err = dsl_sync_task_group_wait(sn.dstg);
+
+	for (dst = list_head(&sn.dstg->dstg_tasks); dst;
+	    dst = list_next(&sn.dstg->dstg_tasks, dst)) {
+		dsl_dataset_t *ds = dst->dst_arg1;
+		if (dst->dst_err)
+			dsl_dataset_name(ds, sn.failed);
+	}
+
+out:
+	while (osn = list_head(&sn.objsets)) {
+		list_remove(&sn.objsets, osn);
+		zil_resume(dmu_objset_zil(osn->os));
+		dmu_objset_close(osn->os);
+		kmem_free(osn, sizeof (struct osnode));
+	}
+	list_destroy(&sn.objsets);
+
+	if (err)
+		(void) strcpy(fsname, sn.failed);
+	dsl_sync_task_group_destroy(sn.dstg);
+	spa_close(spa, FTAG);
+	return (err);
+}
+
+static void
+dmu_objset_sync_dnodes(list_t *list, dmu_tx_t *tx)
+{
+	dnode_t *dn;
+
+	while (dn = list_head(list)) {
+		ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
+		ASSERT(dn->dn_dbuf->db_data_pending);
+		/*
+		 * Initialize dn_zio outside dnode_sync()
+		 * to accomodate meta-dnode
+		 */
+		dn->dn_zio = dn->dn_dbuf->db_data_pending->dr_zio;
+		ASSERT(dn->dn_zio);
+
+		ASSERT3U(dn->dn_nlevels, <=, DN_MAX_LEVELS);
+		list_remove(list, dn);
+		dnode_sync(dn, tx);
+	}
+}
+
+/* ARGSUSED */
+static void
+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;
+	dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;
+
+	ASSERT(bp == os->os_rootbp);
+	ASSERT(BP_GET_TYPE(bp) == DMU_OT_OBJSET);
+	ASSERT(BP_GET_LEVEL(bp) == 0);
+
+	/*
+	 * Update rootbp fill count.
+	 */
+	bp->blk_fill = 1;	/* count the meta-dnode */
+	for (int i = 0; i < dnp->dn_nblkptr; i++)
+		bp->blk_fill += dnp->dn_blkptr[i].blk_fill;
+
+	if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
+		ASSERT(DVA_EQUAL(BP_IDENTITY(bp), BP_IDENTITY(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);
+	}
+}
+
+/* called from dsl */
+void
+dmu_objset_sync(objset_impl_t *os, zio_t *pio, dmu_tx_t *tx)
+{
+	int txgoff;
+	zbookmark_t zb;
+	writeprops_t wp = { 0 };
+	zio_t *zio;
+	list_t *list;
+	dbuf_dirty_record_t *dr;
+
+	dprintf_ds(os->os_dsl_dataset, "txg=%llu\n", tx->tx_txg);
+
+	ASSERT(dmu_tx_is_syncing(tx));
+	/* XXX the write_done callback should really give us the tx... */
+	os->os_synctx = tx;
+
+	if (os->os_dsl_dataset == NULL) {
+		/*
+		 * This is the MOS.  If we have upgraded,
+		 * spa_max_replication() could change, so reset
+		 * os_copies here.
+		 */
+		os->os_copies = spa_max_replication(os->os_spa);
+	}
+
+	/*
+	 * 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);
+	}
+
+	arc_release(os->os_phys_buf, &os->os_phys_buf);
+	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_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
+
+	/*
+	 * Sync meta-dnode - the parent IO for the sync is the root block
+	 */
+	os->os_meta_dnode->dn_zio = zio;
+	dnode_sync(os->os_meta_dnode, tx);
+
+	txgoff = tx->tx_txg & TXG_MASK;
+
+	dmu_objset_sync_dnodes(&os->os_free_dnodes[txgoff], tx);
+	dmu_objset_sync_dnodes(&os->os_dirty_dnodes[txgoff], tx);
+
+	list = &os->os_meta_dnode->dn_dirty_records[txgoff];
+	while (dr = list_head(list)) {
+		ASSERT(dr->dr_dbuf->db_level == 0);
+		list_remove(list, dr);
+		if (dr->dr_zio)
+			zio_nowait(dr->dr_zio);
+	}
+	/*
+	 * Free intent log blocks up to this tx.
+	 */
+	zil_sync(os->os_zil, tx);
+	os->os_phys->os_zil_header = os->os_zil_header;
+	zio_nowait(zio);
+}
+
+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,
+	    usedobjsp, availobjsp);
+}
+
+uint64_t
+dmu_objset_fsid_guid(objset_t *os)
+{
+	return (dsl_dataset_fsid_guid(os->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);
+}
+
+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);
+
+	if (os->os->os_dsl_dataset != NULL)
+		dsl_dataset_stats(os->os->os_dsl_dataset, nv);
+
+	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_TYPE,
+	    os->os->os_phys->os_type);
+}
+
+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));
+	else
+		return (B_FALSE);
+}
+
+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;
+	uint64_t ignored;
+
+	if (ds->ds_phys->ds_snapnames_zapobj == 0)
+		return (ENOENT);
+
+	return (zap_lookup_norm(ds->ds_dir->dd_pool->dp_meta_objset,
+	    ds->ds_phys->ds_snapnames_zapobj, name, 8, 1, &ignored, MT_FIRST,
+	    real, maxlen, conflict));
+}
+
+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;
+	zap_cursor_t cursor;
+	zap_attribute_t attr;
+
+	if (ds->ds_phys->ds_snapnames_zapobj == 0)
+		return (ENOENT);
+
+	zap_cursor_init_serialized(&cursor,
+	    ds->ds_dir->dd_pool->dp_meta_objset,
+	    ds->ds_phys->ds_snapnames_zapobj, *offp);
+
+	if (zap_cursor_retrieve(&cursor, &attr) != 0) {
+		zap_cursor_fini(&cursor);
+		return (ENOENT);
+	}
+
+	if (strlen(attr.za_name) + 1 > namelen) {
+		zap_cursor_fini(&cursor);
+		return (ENAMETOOLONG);
+	}
+
+	(void) strcpy(name, attr.za_name);
+	if (idp)
+		*idp = attr.za_first_integer;
+	if (case_conflict)
+		*case_conflict = attr.za_normalization_conflict;
+	zap_cursor_advance(&cursor);
+	*offp = zap_cursor_serialize(&cursor);
+	zap_cursor_fini(&cursor);
+
+	return (0);
+}
+
+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;
+	zap_cursor_t cursor;
+	zap_attribute_t attr;
+
+	/* there is no next dir on a snapshot! */
+	if (os->os->os_dsl_dataset->ds_object !=
+	    dd->dd_phys->dd_head_dataset_obj)
+		return (ENOENT);
+
+	zap_cursor_init_serialized(&cursor,
+	    dd->dd_pool->dp_meta_objset,
+	    dd->dd_phys->dd_child_dir_zapobj, *offp);
+
+	if (zap_cursor_retrieve(&cursor, &attr) != 0) {
+		zap_cursor_fini(&cursor);
+		return (ENOENT);
+	}
+
+	if (strlen(attr.za_name) + 1 > namelen) {
+		zap_cursor_fini(&cursor);
+		return (ENAMETOOLONG);
+	}
+
+	(void) strcpy(name, attr.za_name);
+	if (idp)
+		*idp = attr.za_first_integer;
+	zap_cursor_advance(&cursor);
+	*offp = zap_cursor_serialize(&cursor);
+	zap_cursor_fini(&cursor);
+
+	return (0);
+}
+
+struct findarg {
+	int (*func)(char *, void *);
+	void *arg;
+};
+
+/* ARGSUSED */
+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));
+}
+
+/*
+ * Find all objsets under name, and for each, call 'func(child_name, 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)
+{
+	struct findarg fa;
+	fa.func = func;
+	fa.arg = arg;
+	return (dmu_objset_find_spa(NULL, name, findfunc, &fa, flags));
+}
+
+/*
+ * Find all objsets under name, call func on each
+ */
+int
+dmu_objset_find_spa(spa_t *spa, const char *name,
+    int func(spa_t *, uint64_t, const char *, void *), void *arg, int flags)
+{
+	dsl_dir_t *dd;
+	dsl_pool_t *dp;
+	dsl_dataset_t *ds;
+	zap_cursor_t zc;
+	zap_attribute_t *attr;
+	char *child;
+	uint64_t thisobj;
+	int err;
+
+	if (name == NULL)
+		name = spa_name(spa);
+	err = dsl_dir_open_spa(spa, name, FTAG, &dd, NULL);
+	if (err)
+		return (err);
+
+	/* Don't visit hidden ($MOS & $ORIGIN) objsets. */
+	if (dd->dd_myname[0] == '$') {
+		dsl_dir_close(dd, FTAG);
+		return (0);
+	}
+
+	thisobj = dd->dd_phys->dd_head_dataset_obj;
+	attr = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
+	dp = dd->dd_pool;
+
+	/*
+	 * Iterate over all children.
+	 */
+	if (flags & DS_FIND_CHILDREN) {
+		for (zap_cursor_init(&zc, dp->dp_meta_objset,
+		    dd->dd_phys->dd_child_dir_zapobj);
+		    zap_cursor_retrieve(&zc, attr) == 0;
+		    (void) zap_cursor_advance(&zc)) {
+			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);
+			err = dmu_objset_find_spa(spa, child, func, arg, flags);
+			kmem_free(child, MAXPATHLEN);
+			if (err)
+				break;
+		}
+		zap_cursor_fini(&zc);
+
+		if (err) {
+			dsl_dir_close(dd, FTAG);
+			kmem_free(attr, sizeof (zap_attribute_t));
+			return (err);
+		}
+	}
+
+	/*
+	 * Iterate over all snapshots.
+	 */
+	if (flags & DS_FIND_SNAPSHOTS) {
+		if (!dsl_pool_sync_context(dp))
+			rw_enter(&dp->dp_config_rwlock, RW_READER);
+		err = dsl_dataset_hold_obj(dp, thisobj, FTAG, &ds);
+		if (!dsl_pool_sync_context(dp))
+			rw_exit(&dp->dp_config_rwlock);
+
+		if (err == 0) {
+			uint64_t snapobj = ds->ds_phys->ds_snapnames_zapobj;
+			dsl_dataset_rele(ds, FTAG);
+
+			for (zap_cursor_init(&zc, dp->dp_meta_objset, snapobj);
+			    zap_cursor_retrieve(&zc, attr) == 0;
+			    (void) zap_cursor_advance(&zc)) {
+				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);
+				err = func(spa, attr->za_first_integer,
+				    child, arg);
+				kmem_free(child, MAXPATHLEN);
+				if (err)
+					break;
+			}
+			zap_cursor_fini(&zc);
+		}
+	}
+
+	dsl_dir_close(dd, FTAG);
+	kmem_free(attr, sizeof (zap_attribute_t));
+
+	if (err)
+		return (err);
+
+	/*
+	 * Apply to self if appropriate.
+	 */
+	err = func(spa, thisobj, name, arg);
+	return (err);
+}
+
+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;
+}
+
+void *
+dmu_objset_get_user(objset_t *os)
+{
+	ASSERT(MUTEX_HELD(&os->os->os_user_ptr_lock));
+	return (os->os->os_user_ptr);
+}