Please welcome ZFS - The last word in file systems.

ZFS file system was ported from OpenSolaris operating system. The code in under
CDDL license.

I'd like to thank all SUN developers that created this great piece of software.

Supported by:	Wheel LTD (http://www.wheel.pl/)
Supported by:	The FreeBSD Foundation (http://www.freebsdfoundation.org/)
Supported by:	Sentex (http://www.sentex.net/)

1 files changed, 1034 insertions, 0 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c
new file mode 100644
index 0000000..07f8c86
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c
@@ -0,0 +1,1034 @@
+/*
+ * 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 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#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/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>
+
+
+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;
+}
+
+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 *winner, *osi;
+	int i, err, checksum;
+
+	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;
+
+		dprintf_bp(osi->os_rootbp, "reading %s", "");
+		err = arc_read(NULL, spa, osi->os_rootbp,
+		    dmu_ot[DMU_OT_OBJSET].ot_byteswap,
+		    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));
+			return (err);
+		}
+		osi->os_phys = osi->os_phys_buf->b_data;
+		arc_release(osi->os_phys_buf, &osi->os_phys_buf);
+	} 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, and
+	 * registering would complicate clone promotion.
+	 */
+	if (ds && ds->ds_phys->ds_num_children == 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_zil = zil_alloc(&osi->os, &osi->os_phys->os_zil_header);
+
+	/*
+	 * Metadata always gets compressed and checksummed.
+	 * If the data checksum is multi-bit correctable, and it's not
+	 * a ZBT-style checksum, then it's suitable for metadata as well.
+	 * Otherwise, the metadata checksum defaults to fletcher4.
+	 */
+	checksum = osi->os_checksum;
+
+	if (zio_checksum_table[checksum].ci_correctable &&
+	    !zio_checksum_table[checksum].ci_zbt)
+		osi->os_md_checksum = checksum;
+	else
+		osi->os_md_checksum = ZIO_CHECKSUM_FLETCHER_4;
+	osi->os_md_compress = ZIO_COMPRESS_LZJB;
+
+	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);
+
+	osi->os_meta_dnode = dnode_special_open(osi,
+	    &osi->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT);
+
+	if (ds != NULL) {
+		winner = dsl_dataset_set_user_ptr(ds, osi, dmu_objset_evict);
+		if (winner) {
+			dmu_objset_evict(ds, osi);
+			osi = winner;
+		}
+	}
+
+	*osip = osi;
+	return (0);
+}
+
+/* called from zpl */
+int
+dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
+    objset_t **osp)
+{
+	dsl_dataset_t *ds;
+	int err;
+	objset_t *os;
+	objset_impl_t *osi;
+
+	os = kmem_alloc(sizeof (objset_t), KM_SLEEP);
+	err = dsl_dataset_open(name, mode, os, &ds);
+	if (err) {
+		kmem_free(os, sizeof (objset_t));
+		return (err);
+	}
+
+	osi = dsl_dataset_get_user_ptr(ds);
+	if (osi == NULL) {
+		err = dmu_objset_open_impl(dsl_dataset_get_spa(ds),
+		    ds, &ds->ds_phys->ds_bp, &osi);
+		if (err) {
+			dsl_dataset_close(ds, mode, os);
+			kmem_free(os, sizeof (objset_t));
+			return (err);
+		}
+	}
+
+	os->os = osi;
+	os->os_mode = mode;
+
+	if (type != DMU_OST_ANY && type != os->os->os_phys->os_type) {
+		dmu_objset_close(os);
+		return (EINVAL);
+	}
+	*osp = os;
+	return (0);
+}
+
+void
+dmu_objset_close(objset_t *os)
+{
+	dsl_dataset_close(os->os->os_dsl_dataset, os->os_mode, os);
+	kmem_free(os, sizeof (objset_t));
+}
+
+int
+dmu_objset_evict_dbufs(objset_t *os, int try)
+{
+	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 && refcount_is_zero(&dn->dn_holds);
+	    dn = list_next(&osi->os_dnodes, dn))
+		continue;
+	if (dn)
+		dnode_add_ref(dn, FTAG);
+
+	while (dn) {
+		dnode_t *next_dn = dn;
+
+		do {
+			next_dn = list_next(&osi->os_dnodes, next_dn);
+		} while (next_dn && refcount_is_zero(&next_dn->dn_holds));
+		if (next_dn)
+			dnode_add_ref(next_dn, FTAG);
+
+		mutex_exit(&osi->os_lock);
+		if (dnode_evict_dbufs(dn, try)) {
+			dnode_rele(dn, FTAG);
+			if (next_dn)
+				dnode_rele(next_dn, FTAG);
+			return (1);
+		}
+		dnode_rele(dn, FTAG);
+		mutex_enter(&osi->os_lock);
+		dn = next_dn;
+	}
+	mutex_exit(&osi->os_lock);
+	return (0);
+}
+
+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 && ds->ds_phys->ds_num_children == 0) {
+		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));
+	}
+
+	/*
+	 * 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, 0);
+
+	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);
+	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));
+	VERIFY(0 == dmu_objset_open_impl(spa, ds, bp, &osi));
+	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, dmu_tx_t *tx);
+	void *userarg;
+	dsl_dataset_t *clone_parent;
+	const char *lastname;
+	dmu_objset_type_t type;
+};
+
+/* 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, 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, tx);
+
+	VERIFY(0 == dsl_dataset_open_obj(dd->dd_pool, dsobj, NULL,
+	    DS_MODE_STANDARD | DS_MODE_READONLY, 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, tx);
+	}
+	dsl_dataset_close(ds, DS_MODE_STANDARD | DS_MODE_READONLY, FTAG);
+}
+
+int
+dmu_objset_create(const char *name, dmu_objset_type_t type,
+    objset_t *clone_parent,
+    void (*func)(objset_t *os, void *arg, 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;
+	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_EXCLUSIVE, &os);
+	if (error == 0) {
+		zil_destroy(dmu_objset_zil(os), B_FALSE);
+		dmu_objset_close(os);
+	}
+
+	return (dsl_dataset_destroy(name));
+}
+
+int
+dmu_objset_rollback(const char *name)
+{
+	int err;
+	objset_t *os;
+
+	err = dmu_objset_open(name, DMU_OST_ANY,
+	    DS_MODE_EXCLUSIVE | DS_MODE_INCONSISTENT, &os);
+	if (err == 0) {
+		err = zil_suspend(dmu_objset_zil(os));
+		if (err == 0)
+			zil_resume(dmu_objset_zil(os));
+		if (err == 0) {
+			/* XXX uncache everything? */
+			err = dsl_dataset_rollback(os->os->os_dsl_dataset);
+		}
+		dmu_objset_close(os);
+	}
+	return (err);
+}
+
+struct snaparg {
+	dsl_sync_task_group_t *dstg;
+	char *snapname;
+	char failed[MAXPATHLEN];
+};
+
+static int
+dmu_objset_snapshot_one(char *name, void *arg)
+{
+	struct snaparg *sn = arg;
+	objset_t *os;
+	dmu_objset_stats_t stat;
+	int err;
+
+	(void) strcpy(sn->failed, name);
+
+	err = dmu_objset_open(name, DMU_OST_ANY, DS_MODE_STANDARD, &os);
+	if (err != 0)
+		return (err);
+
+	/*
+	 * If the objset is in an inconsistent state, return busy.
+	 */
+	dmu_objset_fast_stat(os, &stat);
+	if (stat.dds_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) {
+		dsl_sync_task_create(sn->dstg, dsl_dataset_snapshot_check,
+		    dsl_dataset_snapshot_sync, os, sn->snapname, 3);
+	} else {
+		dmu_objset_close(os);
+	}
+
+	return (err);
+}
+
+int
+dmu_objset_snapshot(char *fsname, char *snapname, boolean_t recursive)
+{
+	dsl_sync_task_t *dst;
+	struct snaparg sn = { 0 };
+	char *cp;
+	spa_t *spa;
+	int err;
+
+	(void) strcpy(sn.failed, fsname);
+
+	cp = strchr(fsname, '/');
+	if (cp) {
+		*cp = '\0';
+		err = spa_open(fsname, &spa, FTAG);
+		*cp = '/';
+	} else {
+		err = spa_open(fsname, &spa, FTAG);
+	}
+	if (err)
+		return (err);
+
+	sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
+	sn.snapname = snapname;
+
+	if (recursive) {
+		err = dmu_objset_find(fsname,
+		    dmu_objset_snapshot_one, &sn, DS_FIND_CHILDREN);
+	} else {
+		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)) {
+		objset_t *os = dst->dst_arg1;
+		if (dst->dst_err)
+			dmu_objset_name(os, sn.failed);
+		zil_resume(dmu_objset_zil(os));
+		dmu_objset_close(os);
+	}
+out:
+	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)
+{
+	objset_impl_t *os = arg;
+	blkptr_t *bp = os->os_rootbp;
+	dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;
+	int i;
+
+	/*
+	 * Update rootbp fill count.
+	 */
+	bp->blk_fill = 1;	/* count the meta-dnode */
+	for (i = 0; i < dnp->dn_nblkptr; i++)
+		bp->blk_fill += dnp->dn_blkptr[i].blk_fill;
+}
+
+/* ARGSUSED */
+static void
+killer(zio_t *zio, arc_buf_t *abuf, void *arg)
+{
+	objset_impl_t *os = arg;
+
+	ASSERT3U(zio->io_error, ==, 0);
+
+	BP_SET_TYPE(zio->io_bp, DMU_OT_OBJSET);
+	BP_SET_LEVEL(zio->io_bp, 0);
+
+	if (!DVA_EQUAL(BP_IDENTITY(zio->io_bp),
+	    BP_IDENTITY(&zio->io_bp_orig))) {
+		if (zio->io_bp_orig.blk_birth == os->os_synctx->tx_txg)
+			dsl_dataset_block_kill(os->os_dsl_dataset,
+			    &zio->io_bp_orig, NULL, os->os_synctx);
+		dsl_dataset_block_born(os->os_dsl_dataset, zio->io_bp,
+		    os->os_synctx);
+	}
+	arc_release(os->os_phys_buf, &os->os_phys_buf);
+}
+
+/* called from dsl */
+void
+dmu_objset_sync(objset_impl_t *os, zio_t *pio, dmu_tx_t *tx)
+{
+	int txgoff;
+	zbookmark_t zb;
+	zio_t *zio;
+	list_t *list;
+	dbuf_dirty_record_t *dr;
+	int zio_flags;
+
+	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;
+	zb.zb_blkid = 0;
+	zio_flags = ZIO_FLAG_MUSTSUCCEED;
+	if (dmu_ot[DMU_OT_OBJSET].ot_metadata || zb.zb_level != 0)
+		zio_flags |= ZIO_FLAG_METADATA;
+	if (BP_IS_OLDER(os->os_rootbp, tx->tx_txg))
+		dsl_dataset_block_kill(os->os_dsl_dataset,
+		    os->os_rootbp, pio, tx);
+	zio = arc_write(pio, os->os_spa, os->os_md_checksum,
+	    os->os_md_compress,
+	    dmu_get_replication_level(os, &zb, DMU_OT_OBJSET),
+	    tx->tx_txg, os->os_rootbp, os->os_phys_buf, ready, killer, os,
+	    ZIO_PRIORITY_ASYNC_WRITE, zio_flags, &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);
+	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_list_next(objset_t *os, int namelen, char *name,
+    uint64_t *idp, uint64_t *offp)
+{
+	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;
+	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);
+}
+
+/*
+ * Find all objsets under name, and for each, call 'func(child_name, arg)'.
+ */
+int
+dmu_objset_find(char *name, int func(char *, void *), void *arg, int flags)
+{
+	dsl_dir_t *dd;
+	objset_t *os;
+	uint64_t snapobj;
+	zap_cursor_t zc;
+	zap_attribute_t attr;
+	char *child;
+	int do_self, err;
+
+	err = dsl_dir_open(name, FTAG, &dd, NULL);
+	if (err)
+		return (err);
+
+	/* NB: the $MOS dir doesn't have a head dataset */
+	do_self = (dd->dd_phys->dd_head_dataset_obj != 0);
+
+	/*
+	 * Iterate over all children.
+	 */
+	if (flags & DS_FIND_CHILDREN) {
+		for (zap_cursor_init(&zc, dd->dd_pool->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);
+
+			/*
+			 * No separating '/' because parent's name ends in /.
+			 */
+			child = kmem_alloc(MAXPATHLEN, KM_SLEEP);
+			/* XXX could probably just use name here */
+			dsl_dir_name(dd, child);
+			(void) strcat(child, "/");
+			(void) strcat(child, attr.za_name);
+			err = dmu_objset_find(child, func, arg, flags);
+			kmem_free(child, MAXPATHLEN);
+			if (err)
+				break;
+		}
+		zap_cursor_fini(&zc);
+
+		if (err) {
+			dsl_dir_close(dd, FTAG);
+			return (err);
+		}
+	}
+
+	/*
+	 * Iterate over all snapshots.
+	 */
+	if ((flags & DS_FIND_SNAPSHOTS) &&
+	    dmu_objset_open(name, DMU_OST_ANY,
+	    DS_MODE_STANDARD | DS_MODE_READONLY, &os) == 0) {
+
+		snapobj = os->os->os_dsl_dataset->ds_phys->ds_snapnames_zapobj;
+		dmu_objset_close(os);
+
+		for (zap_cursor_init(&zc, dd->dd_pool->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);
+			/* XXX could probably just use name here */
+			dsl_dir_name(dd, child);
+			(void) strcat(child, "@");
+			(void) strcat(child, attr.za_name);
+			err = func(child, arg);
+			kmem_free(child, MAXPATHLEN);
+			if (err)
+				break;
+		}
+		zap_cursor_fini(&zc);
+	}
+
+	dsl_dir_close(dd, FTAG);
+
+	if (err)
+		return (err);
+
+	/*
+	 * Apply to self if appropriate.
+	 */
+	if (do_self)
+		err = func(name, arg);
+	return (err);
+}