xref: /illumos-gate/usr/src/uts/common/fs/zfs/dsl_dataset.c (revision eb633035)

/*
 * 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
 * Copyright (c) 2014, Joyent, Inc. All rights reserved.
 * Copyright (c) 2014 RackTop Systems.
 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2016, OmniTI Computer Consulting, Inc. All rights reserved.
 * Copyright 2017 Nexenta Systems, Inc.
 */

#include <sys/dmu_objset.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_synctask.h>
#include <sys/dmu_traverse.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/arc.h>
#include <sys/zio.h>
#include <sys/zap.h>
#include <sys/zfeature.h>
#include <sys/unique.h>
#include <sys/zfs_context.h>
#include <sys/zfs_ioctl.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/vdev.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_onexit.h>
#include <sys/zvol.h>
#include <sys/dsl_scan.h>
#include <sys/dsl_deadlist.h>
#include <sys/dsl_destroy.h>
#include <sys/dsl_userhold.h>
#include <sys/dsl_bookmark.h>
#include <sys/dmu_recv.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <zfs_fletcher.h>

/*
 * The SPA supports block sizes up to 16MB.  However, very large blocks
 * can have an impact on i/o latency (e.g. tying up a spinning disk for
 * ~300ms), and also potentially on the memory allocator.  Therefore,
 * we do not allow the recordsize to be set larger than zfs_max_recordsize
 * (default 1MB).  Larger blocks can be created by changing this tunable,
 * and pools with larger blocks can always be imported and used, regardless
 * of this setting.
 */
int zfs_max_recordsize = 1 * 1024 * 1024;

#define	SWITCH64(x, y) \
	{ \
		uint64_t __tmp = (x); \
		(x) = (y); \
		(y) = __tmp; \
	}

#define	DS_REF_MAX	(1ULL << 62)

extern inline dsl_dataset_phys_t *dsl_dataset_phys(dsl_dataset_t *ds);

static void dsl_dataset_set_remap_deadlist_object(dsl_dataset_t *ds,
    uint64_t obj, dmu_tx_t *tx);
static void dsl_dataset_unset_remap_deadlist_object(dsl_dataset_t *ds,
    dmu_tx_t *tx);

extern int spa_asize_inflation;

static zil_header_t zero_zil;

/*
 * Figure out how much of this delta should be propogated to the dsl_dir
 * layer.  If there's a refreservation, that space has already been
 * partially accounted for in our ancestors.
 */
static int64_t
parent_delta(dsl_dataset_t *ds, int64_t delta)
{
	dsl_dataset_phys_t *ds_phys;
	uint64_t old_bytes, new_bytes;

	if (ds->ds_reserved == 0)
		return (delta);

	ds_phys = dsl_dataset_phys(ds);
	old_bytes = MAX(ds_phys->ds_unique_bytes, ds->ds_reserved);
	new_bytes = MAX(ds_phys->ds_unique_bytes + delta, ds->ds_reserved);

	ASSERT3U(ABS((int64_t)(new_bytes - old_bytes)), <=, ABS(delta));
	return (new_bytes - old_bytes);
}

void
dsl_dataset_block_born(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx)
{
	int used = bp_get_dsize_sync(tx->tx_pool->dp_spa, bp);
	int compressed = BP_GET_PSIZE(bp);
	int uncompressed = BP_GET_UCSIZE(bp);
	int64_t delta;

	dprintf_bp(bp, "ds=%p", ds);

	ASSERT(dmu_tx_is_syncing(tx));
	/* It could have been compressed away to nothing */
	if (BP_IS_HOLE(bp))
		return;
	ASSERT(BP_GET_TYPE(bp) != DMU_OT_NONE);
	ASSERT(DMU_OT_IS_VALID(BP_GET_TYPE(bp)));
	if (ds == NULL) {
		dsl_pool_mos_diduse_space(tx->tx_pool,
		    used, compressed, uncompressed);
		return;
	}

	ASSERT3U(bp->blk_birth, >, dsl_dataset_phys(ds)->ds_prev_snap_txg);
	dmu_buf_will_dirty(ds->ds_dbuf, tx);
	mutex_enter(&ds->ds_lock);
	delta = parent_delta(ds, used);
	dsl_dataset_phys(ds)->ds_referenced_bytes += used;
	dsl_dataset_phys(ds)->ds_compressed_bytes += compressed;
	dsl_dataset_phys(ds)->ds_uncompressed_bytes += uncompressed;
	dsl_dataset_phys(ds)->ds_unique_bytes += used;

	if (BP_GET_LSIZE(bp) > SPA_OLD_MAXBLOCKSIZE) {
		ds->ds_feature_activation_needed[SPA_FEATURE_LARGE_BLOCKS] =
		    B_TRUE;
	}

	spa_feature_t f = zio_checksum_to_feature(BP_GET_CHECKSUM(bp));
	if (f != SPA_FEATURE_NONE)
		ds->ds_feature_activation_needed[f] = B_TRUE;

	mutex_exit(&ds->ds_lock);
	dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD, delta,
	    compressed, uncompressed, tx);
	dsl_dir_transfer_space(ds->ds_dir, used - delta,
	    DD_USED_REFRSRV, DD_USED_HEAD, tx);
}

/*
 * Called when the specified segment has been remapped, and is thus no
 * longer referenced in the head dataset.  The vdev must be indirect.
 *
 * If the segment is referenced by a snapshot, put it on the remap deadlist.
 * Otherwise, add this segment to the obsolete spacemap.
 */
void
dsl_dataset_block_remapped(dsl_dataset_t *ds, uint64_t vdev, uint64_t offset,
    uint64_t size, uint64_t birth, dmu_tx_t *tx)
{
	spa_t *spa = ds->ds_dir->dd_pool->dp_spa;

	ASSERT(dmu_tx_is_syncing(tx));
	ASSERT(birth <= tx->tx_txg);
	ASSERT(!ds->ds_is_snapshot);

	if (birth > dsl_dataset_phys(ds)->ds_prev_snap_txg) {
		spa_vdev_indirect_mark_obsolete(spa, vdev, offset, size, tx);
	} else {
		blkptr_t fakebp;
		dva_t *dva = &fakebp.blk_dva[0];

		ASSERT(ds != NULL);

		mutex_enter(&ds->ds_remap_deadlist_lock);
		if (!dsl_dataset_remap_deadlist_exists(ds)) {
			dsl_dataset_create_remap_deadlist(ds, tx);
		}
		mutex_exit(&ds->ds_remap_deadlist_lock);

		BP_ZERO(&fakebp);
		fakebp.blk_birth = birth;
		DVA_SET_VDEV(dva, vdev);
		DVA_SET_OFFSET(dva, offset);
		DVA_SET_ASIZE(dva, size);

		dsl_deadlist_insert(&ds->ds_remap_deadlist, &fakebp, tx);
	}
}

int
dsl_dataset_block_kill(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx,
    boolean_t async)
{
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;

	int used = bp_get_dsize_sync(spa, bp);
	int compressed = BP_GET_PSIZE(bp);
	int uncompressed = BP_GET_UCSIZE(bp);

	if (BP_IS_HOLE(bp))
		return (0);

	ASSERT(dmu_tx_is_syncing(tx));
	ASSERT(bp->blk_birth <= tx->tx_txg);

	if (ds == NULL) {
		dsl_free(tx->tx_pool, tx->tx_txg, bp);
		dsl_pool_mos_diduse_space(tx->tx_pool,
		    -used, -compressed, -uncompressed);
		return (used);
	}
	ASSERT3P(tx->tx_pool, ==, ds->ds_dir->dd_pool);

	ASSERT(!ds->ds_is_snapshot);
	dmu_buf_will_dirty(ds->ds_dbuf, tx);

	if (bp->blk_birth > dsl_dataset_phys(ds)->ds_prev_snap_txg) {
		int64_t delta;

		dprintf_bp(bp, "freeing ds=%llu", ds->ds_object);
		dsl_free(tx->tx_pool, tx->tx_txg, bp);

		mutex_enter(&ds->ds_lock);
		ASSERT(dsl_dataset_phys(ds)->ds_unique_bytes >= used ||
		    !DS_UNIQUE_IS_ACCURATE(ds));
		delta = parent_delta(ds, -used);
		dsl_dataset_phys(ds)->ds_unique_bytes -= used;
		mutex_exit(&ds->ds_lock);
		dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD,
		    delta, -compressed, -uncompressed, tx);
		dsl_dir_transfer_space(ds->ds_dir, -used - delta,
		    DD_USED_REFRSRV, DD_USED_HEAD, tx);
	} else {
		dprintf_bp(bp, "putting on dead list: %s", "");
		if (async) {
			/*
			 * We are here as part of zio's write done callback,
			 * which means we're a zio interrupt thread.  We can't
			 * call dsl_deadlist_insert() now because it may block
			 * waiting for I/O.  Instead, put bp on the deferred
			 * queue and let dsl_pool_sync() finish the job.
			 */
			bplist_append(&ds->ds_pending_deadlist, bp);
		} else {
			dsl_deadlist_insert(&ds->ds_deadlist, bp, tx);
		}
		ASSERT3U(ds->ds_prev->ds_object, ==,
		    dsl_dataset_phys(ds)->ds_prev_snap_obj);
		ASSERT(dsl_dataset_phys(ds->ds_prev)->ds_num_children > 0);
		/* if (bp->blk_birth > prev prev snap txg) prev unique += bs */
		if (dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj ==
		    ds->ds_object && bp->blk_birth >
		    dsl_dataset_phys(ds->ds_prev)->ds_prev_snap_txg) {
			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
			mutex_enter(&ds->ds_prev->ds_lock);
			dsl_dataset_phys(ds->ds_prev)->ds_unique_bytes += used;
			mutex_exit(&ds->ds_prev->ds_lock);
		}
		if (bp->blk_birth > ds->ds_dir->dd_origin_txg) {
			dsl_dir_transfer_space(ds->ds_dir, used,
			    DD_USED_HEAD, DD_USED_SNAP, tx);
		}
	}
	mutex_enter(&ds->ds_lock);
	ASSERT3U(dsl_dataset_phys(ds)->ds_referenced_bytes, >=, used);
	dsl_dataset_phys(ds)->ds_referenced_bytes -= used;
	ASSERT3U(dsl_dataset_phys(ds)->ds_compressed_bytes, >=, compressed);
	dsl_dataset_phys(ds)->ds_compressed_bytes -= compressed;
	ASSERT3U(dsl_dataset_phys(ds)->ds_uncompressed_bytes, >=, uncompressed);
	dsl_dataset_phys(ds)->ds_uncompressed_bytes -= uncompressed;
	mutex_exit(&ds->ds_lock);

	return (used);
}

/*
 * We have to release the fsid syncronously or we risk that a subsequent
 * mount of the same dataset will fail to unique_insert the fsid.  This
 * failure would manifest itself as the fsid of this dataset changing
 * between mounts which makes NFS clients quite unhappy.
 */
static void
dsl_dataset_evict_sync(void *dbu)
{
	dsl_dataset_t *ds = dbu;

	ASSERT(ds->ds_owner == NULL);

	unique_remove(ds->ds_fsid_guid);
}

static void
dsl_dataset_evict_async(void *dbu)
{
	dsl_dataset_t *ds = dbu;

	ASSERT(ds->ds_owner == NULL);

	ds->ds_dbuf = NULL;

	if (ds->ds_objset != NULL)
		dmu_objset_evict(ds->ds_objset);

	if (ds->ds_prev) {
		dsl_dataset_rele(ds->ds_prev, ds);
		ds->ds_prev = NULL;
	}

	bplist_destroy(&ds->ds_pending_deadlist);
	if (dsl_deadlist_is_open(&ds->ds_deadlist))
		dsl_deadlist_close(&ds->ds_deadlist);
	if (dsl_deadlist_is_open(&ds->ds_remap_deadlist))
		dsl_deadlist_close(&ds->ds_remap_deadlist);
	if (ds->ds_dir)
		dsl_dir_async_rele(ds->ds_dir, ds);

	ASSERT(!list_link_active(&ds->ds_synced_link));

	list_destroy(&ds->ds_prop_cbs);
	mutex_destroy(&ds->ds_lock);
	mutex_destroy(&ds->ds_opening_lock);
	mutex_destroy(&ds->ds_sendstream_lock);
	mutex_destroy(&ds->ds_remap_deadlist_lock);
	zfs_refcount_destroy(&ds->ds_longholds);
	rrw_destroy(&ds->ds_bp_rwlock);

	kmem_free(ds, sizeof (dsl_dataset_t));
}

int
dsl_dataset_get_snapname(dsl_dataset_t *ds)
{
	dsl_dataset_phys_t *headphys;
	int err;
	dmu_buf_t *headdbuf;
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	objset_t *mos = dp->dp_meta_objset;

	if (ds->ds_snapname[0])
		return (0);
	if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0)
		return (0);

	err = dmu_bonus_hold(mos, dsl_dir_phys(ds->ds_dir)->dd_head_dataset_obj,
	    FTAG, &headdbuf);
	if (err != 0)
		return (err);
	headphys = headdbuf->db_data;
	err = zap_value_search(dp->dp_meta_objset,
	    headphys->ds_snapnames_zapobj, ds->ds_object, 0, ds->ds_snapname);
	dmu_buf_rele(headdbuf, FTAG);
	return (err);
}

int
dsl_dataset_snap_lookup(dsl_dataset_t *ds, const char *name, uint64_t *value)
{
	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
	uint64_t snapobj = dsl_dataset_phys(ds)->ds_snapnames_zapobj;
	matchtype_t mt = 0;
	int err;

	if (dsl_dataset_phys(ds)->ds_flags & DS_FLAG_CI_DATASET)
		mt = MT_NORMALIZE;

	err = zap_lookup_norm(mos, snapobj, name, 8, 1,
	    value, mt, NULL, 0, NULL);
	if (err == ENOTSUP && (mt & MT_NORMALIZE))
		err = zap_lookup(mos, snapobj, name, 8, 1, value);
	return (err);
}

int
dsl_dataset_snap_remove(dsl_dataset_t *ds, const char *name, dmu_tx_t *tx,
    boolean_t adj_cnt)
{
	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
	uint64_t snapobj = dsl_dataset_phys(ds)->ds_snapnames_zapobj;
	matchtype_t mt = 0;
	int err;

	dsl_dir_snap_cmtime_update(ds->ds_dir);

	if (dsl_dataset_phys(ds)->ds_flags & DS_FLAG_CI_DATASET)
		mt = MT_NORMALIZE;

	err = zap_remove_norm(mos, snapobj, name, mt, tx);
	if (err == ENOTSUP && (mt & MT_NORMALIZE))
		err = zap_remove(mos, snapobj, name, tx);

	if (err == 0 && adj_cnt)
		dsl_fs_ss_count_adjust(ds->ds_dir, -1,
		    DD_FIELD_SNAPSHOT_COUNT, tx);

	return (err);
}

boolean_t
dsl_dataset_try_add_ref(dsl_pool_t *dp, dsl_dataset_t *ds, void *tag)
{
	dmu_buf_t *dbuf = ds->ds_dbuf;
	boolean_t result = B_FALSE;

	if (dbuf != NULL && dmu_buf_try_add_ref(dbuf, dp->dp_meta_objset,
	    ds->ds_object, DMU_BONUS_BLKID, tag)) {

		if (ds == dmu_buf_get_user(dbuf))
			result = B_TRUE;
		else
			dmu_buf_rele(dbuf, tag);
	}

	return (result);
}

int
dsl_dataset_hold_obj(dsl_pool_t *dp, uint64_t dsobj, void *tag,
    dsl_dataset_t **dsp)
{
	objset_t *mos = dp->dp_meta_objset;
	dmu_buf_t *dbuf;
	dsl_dataset_t *ds;
	int err;
	dmu_object_info_t doi;

	ASSERT(dsl_pool_config_held(dp));

	err = dmu_bonus_hold(mos, dsobj, tag, &dbuf);
	if (err != 0)
		return (err);

	/* Make sure dsobj has the correct object type. */
	dmu_object_info_from_db(dbuf, &doi);
	if (doi.doi_bonus_type != DMU_OT_DSL_DATASET) {
		dmu_buf_rele(dbuf, tag);
		return (SET_ERROR(EINVAL));
	}

	ds = dmu_buf_get_user(dbuf);
	if (ds == NULL) {
		dsl_dataset_t *winner = NULL;

		ds = kmem_zalloc(sizeof (dsl_dataset_t), KM_SLEEP);
		ds->ds_dbuf = dbuf;
		ds->ds_object = dsobj;
		ds->ds_is_snapshot = dsl_dataset_phys(ds)->ds_num_children != 0;

		err = dsl_dir_hold_obj(dp, dsl_dataset_phys(ds)->ds_dir_obj,
		    NULL, ds, &ds->ds_dir);
		if (err != 0) {
			kmem_free(ds, sizeof (dsl_dataset_t));
			dmu_buf_rele(dbuf, tag);
			return (err);
		}

		mutex_init(&ds->ds_lock, NULL, MUTEX_DEFAULT, NULL);
		mutex_init(&ds->ds_opening_lock, NULL, MUTEX_DEFAULT, NULL);
		mutex_init(&ds->ds_sendstream_lock, NULL, MUTEX_DEFAULT, NULL);
		mutex_init(&ds->ds_remap_deadlist_lock,
		    NULL, MUTEX_DEFAULT, NULL);
		rrw_init(&ds->ds_bp_rwlock, B_FALSE);
		zfs_refcount_create(&ds->ds_longholds);

		bplist_create(&ds->ds_pending_deadlist);

		list_create(&ds->ds_sendstreams, sizeof (dmu_sendarg_t),
		    offsetof(dmu_sendarg_t, dsa_link));

		list_create(&ds->ds_prop_cbs, sizeof (dsl_prop_cb_record_t),
		    offsetof(dsl_prop_cb_record_t, cbr_ds_node));

		if (doi.doi_type == DMU_OTN_ZAP_METADATA) {
			for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
				if (!(spa_feature_table[f].fi_flags &
				    ZFEATURE_FLAG_PER_DATASET))
					continue;
				err = zap_contains(mos, dsobj,
				    spa_feature_table[f].fi_guid);
				if (err == 0) {
					ds->ds_feature_inuse[f] = B_TRUE;
				} else {
					ASSERT3U(err, ==, ENOENT);
					err = 0;
				}
			}
		}

		if (!ds->ds_is_snapshot) {
			ds->ds_snapname[0] = '\0';
			if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
				err = dsl_dataset_hold_obj(dp,
				    dsl_dataset_phys(ds)->ds_prev_snap_obj,
				    ds, &ds->ds_prev);
			}
			if (doi.doi_type == DMU_OTN_ZAP_METADATA) {
				int zaperr = zap_lookup(mos, ds->ds_object,
				    DS_FIELD_BOOKMARK_NAMES,
				    sizeof (ds->ds_bookmarks), 1,
				    &ds->ds_bookmarks);
				if (zaperr != ENOENT)
					VERIFY0(zaperr);
			}
		} else {
			if (zfs_flags & ZFS_DEBUG_SNAPNAMES)
				err = dsl_dataset_get_snapname(ds);
			if (err == 0 &&
			    dsl_dataset_phys(ds)->ds_userrefs_obj != 0) {
				err = zap_count(
				    ds->ds_dir->dd_pool->dp_meta_objset,
				    dsl_dataset_phys(ds)->ds_userrefs_obj,
				    &ds->ds_userrefs);
			}
		}

		if (err == 0 && !ds->ds_is_snapshot) {
			err = dsl_prop_get_int_ds(ds,
			    zfs_prop_to_name(ZFS_PROP_REFRESERVATION),
			    &ds->ds_reserved);
			if (err == 0) {
				err = dsl_prop_get_int_ds(ds,
				    zfs_prop_to_name(ZFS_PROP_REFQUOTA),
				    &ds->ds_quota);
			}
		} else {
			ds->ds_reserved = ds->ds_quota = 0;
		}

		if (err == 0 && ds->ds_dir->dd_crypto_obj != 0 &&
		    ds->ds_is_snapshot &&
		    zap_contains(mos, dsobj, DS_FIELD_IVSET_GUID) != 0) {
			dp->dp_spa->spa_errata =
			    ZPOOL_ERRATA_ZOL_8308_ENCRYPTION;
		}

		dsl_deadlist_open(&ds->ds_deadlist,
		    mos, dsl_dataset_phys(ds)->ds_deadlist_obj);
		uint64_t remap_deadlist_obj =
		    dsl_dataset_get_remap_deadlist_object(ds);
		if (remap_deadlist_obj != 0) {
			dsl_deadlist_open(&ds->ds_remap_deadlist, mos,
			    remap_deadlist_obj);
		}

		dmu_buf_init_user(&ds->ds_dbu, dsl_dataset_evict_sync,
		    dsl_dataset_evict_async, &ds->ds_dbuf);
		if (err == 0)
			winner = dmu_buf_set_user_ie(dbuf, &ds->ds_dbu);

		if (err != 0 || winner != NULL) {
			bplist_destroy(&ds->ds_pending_deadlist);
			dsl_deadlist_close(&ds->ds_deadlist);
			if (dsl_deadlist_is_open(&ds->ds_remap_deadlist))
				dsl_deadlist_close(&ds->ds_remap_deadlist);
			if (ds->ds_prev)
				dsl_dataset_rele(ds->ds_prev, ds);
			dsl_dir_rele(ds->ds_dir, ds);
			list_destroy(&ds->ds_prop_cbs);
			list_destroy(&ds->ds_sendstreams);
			mutex_destroy(&ds->ds_lock);
			mutex_destroy(&ds->ds_opening_lock);
			mutex_destroy(&ds->ds_sendstream_lock);
			mutex_destroy(&ds->ds_remap_deadlist_lock);
			zfs_refcount_destroy(&ds->ds_longholds);
			rrw_destroy(&ds->ds_bp_rwlock);
			kmem_free(ds, sizeof (dsl_dataset_t));
			if (err != 0) {
				dmu_buf_rele(dbuf, tag);
				return (err);
			}
			ds = winner;
		} else {
			ds->ds_fsid_guid =
			    unique_insert(dsl_dataset_phys(ds)->ds_fsid_guid);
			if (ds->ds_fsid_guid !=
			    dsl_dataset_phys(ds)->ds_fsid_guid) {
				zfs_dbgmsg("ds_fsid_guid changed from "
				    "%llx to %llx for pool %s dataset id %llu",
				    (long long)
				    dsl_dataset_phys(ds)->ds_fsid_guid,
				    (long long)ds->ds_fsid_guid,
				    spa_name(dp->dp_spa),
				    dsobj);
			}
		}
	}

	ASSERT3P(ds->ds_dbuf, ==, dbuf);
	ASSERT3P(dsl_dataset_phys(ds), ==, dbuf->db_data);
	ASSERT(dsl_dataset_phys(ds)->ds_prev_snap_obj != 0 ||
	    spa_version(dp->dp_spa) < SPA_VERSION_ORIGIN ||
	    dp->dp_origin_snap == NULL || ds == dp->dp_origin_snap);
	*dsp = ds;

	return (0);
}

int
dsl_dataset_create_key_mapping(dsl_dataset_t *ds)
{
	dsl_dir_t *dd = ds->ds_dir;

	if (dd->dd_crypto_obj == 0)
		return (0);

	return (spa_keystore_create_mapping(dd->dd_pool->dp_spa,
	    ds, ds, &ds->ds_key_mapping));
}

int
dsl_dataset_hold_obj_flags(dsl_pool_t *dp, uint64_t dsobj,
    ds_hold_flags_t flags, void *tag, dsl_dataset_t **dsp)
{
	int err;

	err = dsl_dataset_hold_obj(dp, dsobj, tag, dsp);
	if (err != 0)
		return (err);

	ASSERT3P(*dsp, !=, NULL);

	if (flags & DS_HOLD_FLAG_DECRYPT) {
		err = dsl_dataset_create_key_mapping(*dsp);
		if (err != 0)
			dsl_dataset_rele(*dsp, tag);
	}

	return (err);
}

int
dsl_dataset_hold_flags(dsl_pool_t *dp, const char *name, ds_hold_flags_t flags,
    void *tag, dsl_dataset_t **dsp)
{
	dsl_dir_t *dd;
	const char *snapname;
	uint64_t obj;
	int err = 0;
	dsl_dataset_t *ds;

	err = dsl_dir_hold(dp, name, FTAG, &dd, &snapname);
	if (err != 0)
		return (err);

	ASSERT(dsl_pool_config_held(dp));
	obj = dsl_dir_phys(dd)->dd_head_dataset_obj;
	if (obj != 0)
		err = dsl_dataset_hold_obj_flags(dp, obj, flags, tag, &ds);
	else
		err = SET_ERROR(ENOENT);

	/* we may be looking for a snapshot */
	if (err == 0 && snapname != NULL) {
		dsl_dataset_t *snap_ds;

		if (*snapname++ != '@') {
			dsl_dataset_rele_flags(ds, flags, tag);
			dsl_dir_rele(dd, FTAG);
			return (SET_ERROR(ENOENT));
		}

		dprintf("looking for snapshot '%s'\n", snapname);
		err = dsl_dataset_snap_lookup(ds, snapname, &obj);
		if (err == 0) {
			err = dsl_dataset_hold_obj_flags(dp, obj, flags, tag,
			    &snap_ds);
		}
		dsl_dataset_rele_flags(ds, flags, tag);

		if (err == 0) {
			mutex_enter(&snap_ds->ds_lock);
			if (snap_ds->ds_snapname[0] == 0)
				(void) strlcpy(snap_ds->ds_snapname, snapname,
				    sizeof (snap_ds->ds_snapname));
			mutex_exit(&snap_ds->ds_lock);
			ds = snap_ds;
		}
	}
	if (err == 0)
		*dsp = ds;
	dsl_dir_rele(dd, FTAG);
	return (err);
}

int
dsl_dataset_hold(dsl_pool_t *dp, const char *name, void *tag,
    dsl_dataset_t **dsp)
{
	return (dsl_dataset_hold_flags(dp, name, 0, tag, dsp));
}

int
dsl_dataset_own_obj(dsl_pool_t *dp, uint64_t dsobj, ds_hold_flags_t flags,
    void *tag, dsl_dataset_t **dsp)
{
	int err = dsl_dataset_hold_obj_flags(dp, dsobj, flags, tag, dsp);
	if (err != 0)
		return (err);
	if (!dsl_dataset_tryown(*dsp, tag)) {
		dsl_dataset_rele_flags(*dsp, flags, tag);
		*dsp = NULL;
		return (SET_ERROR(EBUSY));
	}
	return (0);
}

int
dsl_dataset_own(dsl_pool_t *dp, const char *name, ds_hold_flags_t flags,
    void *tag, dsl_dataset_t **dsp)
{
	int err = dsl_dataset_hold_flags(dp, name, flags, tag, dsp);
	if (err != 0)
		return (err);
	if (!dsl_dataset_tryown(*dsp, tag)) {
		dsl_dataset_rele_flags(*dsp, flags, tag);
		return (SET_ERROR(EBUSY));
	}
	return (0);
}

/*
 * See the comment above dsl_pool_hold() for details.  In summary, a long
 * hold is used to prevent destruction of a dataset while the pool hold
 * is dropped, allowing other concurrent operations (e.g. spa_sync()).
 *
 * The dataset and pool must be held when this function is called.  After it
 * is called, the pool hold may be released while the dataset is still held
 * and accessed.
 */
void
dsl_dataset_long_hold(dsl_dataset_t *ds, void *tag)
{
	ASSERT(dsl_pool_config_held(ds->ds_dir->dd_pool));
	(void) zfs_refcount_add(&ds->ds_longholds, tag);
}

void
dsl_dataset_long_rele(dsl_dataset_t *ds, void *tag)
{
	(void) zfs_refcount_remove(&ds->ds_longholds, tag);
}

/* Return B_TRUE if there are any long holds on this dataset. */
boolean_t
dsl_dataset_long_held(dsl_dataset_t *ds)
{
	return (!zfs_refcount_is_zero(&ds->ds_longholds));
}

void
dsl_dataset_name(dsl_dataset_t *ds, char *name)
{
	if (ds == NULL) {
		(void) strcpy(name, "mos");
	} else {
		dsl_dir_name(ds->ds_dir, name);
		VERIFY0(dsl_dataset_get_snapname(ds));
		if (ds->ds_snapname[0]) {
			VERIFY3U(strlcat(name, "@", ZFS_MAX_DATASET_NAME_LEN),
			    <, ZFS_MAX_DATASET_NAME_LEN);
			/*
			 * We use a "recursive" mutex so that we
			 * can call dprintf_ds() with ds_lock held.
			 */
			if (!MUTEX_HELD(&ds->ds_lock)) {
				mutex_enter(&ds->ds_lock);
				VERIFY3U(strlcat(name, ds->ds_snapname,
				    ZFS_MAX_DATASET_NAME_LEN), <,
				    ZFS_MAX_DATASET_NAME_LEN);
				mutex_exit(&ds->ds_lock);
			} else {
				VERIFY3U(strlcat(name, ds->ds_snapname,
				    ZFS_MAX_DATASET_NAME_LEN), <,
				    ZFS_MAX_DATASET_NAME_LEN);
			}
		}
	}
}

int
dsl_dataset_namelen(dsl_dataset_t *ds)
{
	VERIFY0(dsl_dataset_get_snapname(ds));
	mutex_enter(&ds->ds_lock);
	int len = dsl_dir_namelen(ds->ds_dir) + 1 + strlen(ds->ds_snapname);
	mutex_exit(&ds->ds_lock);
	return (len);
}

void
dsl_dataset_rele(dsl_dataset_t *ds, void *tag)
{
	dmu_buf_rele(ds->ds_dbuf, tag);
}

void
dsl_dataset_remove_key_mapping(dsl_dataset_t *ds)
{
	dsl_dir_t *dd = ds->ds_dir;

	if (dd == NULL || dd->dd_crypto_obj == 0)
		return;

	(void) spa_keystore_remove_mapping(dd->dd_pool->dp_spa,
	    ds->ds_object, ds);
}

void
dsl_dataset_rele_flags(dsl_dataset_t *ds, ds_hold_flags_t flags, void *tag)
{
	if (flags & DS_HOLD_FLAG_DECRYPT)
		dsl_dataset_remove_key_mapping(ds);

	dsl_dataset_rele(ds, tag);
}

void
dsl_dataset_disown(dsl_dataset_t *ds, ds_hold_flags_t flags, void *tag)
{
	ASSERT3P(ds->ds_owner, ==, tag);
	ASSERT(ds->ds_dbuf != NULL);

	mutex_enter(&ds->ds_lock);
	ds->ds_owner = NULL;
	mutex_exit(&ds->ds_lock);
	dsl_dataset_long_rele(ds, tag);
	dsl_dataset_rele_flags(ds, flags, tag);
}

boolean_t
dsl_dataset_tryown(dsl_dataset_t *ds, void *tag)
{
	boolean_t gotit = FALSE;

	ASSERT(dsl_pool_config_held(ds->ds_dir->dd_pool));
	mutex_enter(&ds->ds_lock);
	if (ds->ds_owner == NULL && !DS_IS_INCONSISTENT(ds)) {
		ds->ds_owner = tag;
		dsl_dataset_long_hold(ds, tag);
		gotit = TRUE;
	}
	mutex_exit(&ds->ds_lock);
	return (gotit);
}

boolean_t
dsl_dataset_has_owner(dsl_dataset_t *ds)
{
	boolean_t rv;
	mutex_enter(&ds->ds_lock);
	rv = (ds->ds_owner != NULL);
	mutex_exit(&ds->ds_lock);
	return (rv);
}

void
dsl_dataset_activate_feature(uint64_t dsobj, spa_feature_t f, dmu_tx_t *tx)
{
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
	objset_t *mos = dmu_tx_pool(tx)->dp_meta_objset;
	uint64_t zero = 0;

	VERIFY(spa_feature_table[f].fi_flags & ZFEATURE_FLAG_PER_DATASET);

	spa_feature_incr(spa, f, tx);
	dmu_object_zapify(mos, dsobj, DMU_OT_DSL_DATASET, tx);

	VERIFY0(zap_add(mos, dsobj, spa_feature_table[f].fi_guid,
	    sizeof (zero), 1, &zero, tx));
}

void
dsl_dataset_deactivate_feature(uint64_t dsobj, spa_feature_t f, dmu_tx_t *tx)
{
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
	objset_t *mos = dmu_tx_pool(tx)->dp_meta_objset;

	VERIFY(spa_feature_table[f].fi_flags & ZFEATURE_FLAG_PER_DATASET);

	VERIFY0(zap_remove(mos, dsobj, spa_feature_table[f].fi_guid, tx));
	spa_feature_decr(spa, f, tx);
}

uint64_t
dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
    dsl_crypto_params_t *dcp, uint64_t flags, dmu_tx_t *tx)
{
	dsl_pool_t *dp = dd->dd_pool;
	dmu_buf_t *dbuf;
	dsl_dataset_phys_t *dsphys;
	uint64_t dsobj;
	objset_t *mos = dp->dp_meta_objset;

	if (origin == NULL)
		origin = dp->dp_origin_snap;

	ASSERT(origin == NULL || origin->ds_dir->dd_pool == dp);
	ASSERT(origin == NULL || dsl_dataset_phys(origin)->ds_num_children > 0);
	ASSERT(dmu_tx_is_syncing(tx));
	ASSERT(dsl_dir_phys(dd)->dd_head_dataset_obj == 0);

	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
	VERIFY0(dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
	dmu_buf_will_dirty(dbuf, tx);
	dsphys = dbuf->db_data;
	bzero(dsphys, sizeof (dsl_dataset_phys_t));
	dsphys->ds_dir_obj = dd->dd_object;
	dsphys->ds_flags = flags;
	dsphys->ds_fsid_guid = unique_create();
	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
	    sizeof (dsphys->ds_guid));
	dsphys->ds_snapnames_zapobj =
	    zap_create_norm(mos, U8_TEXTPREP_TOUPPER, DMU_OT_DSL_DS_SNAP_MAP,
	    DMU_OT_NONE, 0, tx);
	dsphys->ds_creation_time = gethrestime_sec();
	dsphys->ds_creation_txg = tx->tx_txg == TXG_INITIAL ? 1 : tx->tx_txg;

	if (origin == NULL) {
		dsphys->ds_deadlist_obj = dsl_deadlist_alloc(mos, tx);
	} else {
		dsl_dataset_t *ohds; /* head of the origin snapshot */

		dsphys->ds_prev_snap_obj = origin->ds_object;
		dsphys->ds_prev_snap_txg =
		    dsl_dataset_phys(origin)->ds_creation_txg;
		dsphys->ds_referenced_bytes =
		    dsl_dataset_phys(origin)->ds_referenced_bytes;
		dsphys->ds_compressed_bytes =
		    dsl_dataset_phys(origin)->ds_compressed_bytes;
		dsphys->ds_uncompressed_bytes =
		    dsl_dataset_phys(origin)->ds_uncompressed_bytes;
		rrw_enter(&origin->ds_bp_rwlock, RW_READER, FTAG);
		dsphys->ds_bp = dsl_dataset_phys(origin)->ds_bp;
		rrw_exit(&origin->ds_bp_rwlock, FTAG);

		/*
		 * Inherit flags that describe the dataset's contents
		 * (INCONSISTENT) or properties (Case Insensitive).
		 */
		dsphys->ds_flags |= dsl_dataset_phys(origin)->ds_flags &
		    (DS_FLAG_INCONSISTENT | DS_FLAG_CI_DATASET);

		for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
			if (origin->ds_feature_inuse[f])
				dsl_dataset_activate_feature(dsobj, f, tx);
		}

		dmu_buf_will_dirty(origin->ds_dbuf, tx);
		dsl_dataset_phys(origin)->ds_num_children++;

		VERIFY0(dsl_dataset_hold_obj(dp,
		    dsl_dir_phys(origin->ds_dir)->dd_head_dataset_obj,
		    FTAG, &ohds));
		dsphys->ds_deadlist_obj = dsl_deadlist_clone(&ohds->ds_deadlist,
		    dsphys->ds_prev_snap_txg, dsphys->ds_prev_snap_obj, tx);
		dsl_dataset_rele(ohds, FTAG);

		if (spa_version(dp->dp_spa) >= SPA_VERSION_NEXT_CLONES) {
			if (dsl_dataset_phys(origin)->ds_next_clones_obj == 0) {
				dsl_dataset_phys(origin)->ds_next_clones_obj =
				    zap_create(mos,
				    DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
			}
			VERIFY0(zap_add_int(mos,
			    dsl_dataset_phys(origin)->ds_next_clones_obj,
			    dsobj, tx));
		}

		dmu_buf_will_dirty(dd->dd_dbuf, tx);
		dsl_dir_phys(dd)->dd_origin_obj = origin->ds_object;
		if (spa_version(dp->dp_spa) >= SPA_VERSION_DIR_CLONES) {
			if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) {
				dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
				dsl_dir_phys(origin->ds_dir)->dd_clones =
				    zap_create(mos,
				    DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
			}
			VERIFY0(zap_add_int(mos,
			    dsl_dir_phys(origin->ds_dir)->dd_clones,
			    dsobj, tx));
		}
	}

	/* handle encryption */
	dsl_dataset_create_crypt_sync(dsobj, dd, origin, dcp, tx);

	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
		dsphys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;

	dmu_buf_rele(dbuf, FTAG);

	dmu_buf_will_dirty(dd->dd_dbuf, tx);
	dsl_dir_phys(dd)->dd_head_dataset_obj = dsobj;

	return (dsobj);
}

static void
dsl_dataset_zero_zil(dsl_dataset_t *ds, dmu_tx_t *tx)
{
	objset_t *os;

	VERIFY0(dmu_objset_from_ds(ds, &os));
	if (bcmp(&os->os_zil_header, &zero_zil, sizeof (zero_zil)) != 0) {
		dsl_pool_t *dp = ds->ds_dir->dd_pool;
		zio_t *zio;

		bzero(&os->os_zil_header, sizeof (os->os_zil_header));
		if (os->os_encrypted)
			os->os_next_write_raw[tx->tx_txg & TXG_MASK] = B_TRUE;

		zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
		dsl_dataset_sync(ds, zio, tx);
		VERIFY0(zio_wait(zio));

		/* dsl_dataset_sync_done will drop this reference. */
		dmu_buf_add_ref(ds->ds_dbuf, ds);
		dsl_dataset_sync_done(ds, tx);
	}
}

uint64_t
dsl_dataset_create_sync(dsl_dir_t *pdd, const char *lastname,
    dsl_dataset_t *origin, uint64_t flags, cred_t *cr,
    dsl_crypto_params_t *dcp, dmu_tx_t *tx)
{
	dsl_pool_t *dp = pdd->dd_pool;
	uint64_t dsobj, ddobj;
	dsl_dir_t *dd;

	ASSERT(dmu_tx_is_syncing(tx));
	ASSERT(lastname[0] != '@');

	ddobj = dsl_dir_create_sync(dp, pdd, lastname, tx);
	VERIFY0(dsl_dir_hold_obj(dp, ddobj, lastname, FTAG, &dd));

	dsobj = dsl_dataset_create_sync_dd(dd, origin, dcp,
	    flags & ~DS_CREATE_FLAG_NODIRTY, tx);

	dsl_deleg_set_create_perms(dd, tx, cr);

	/*
	 * Since we're creating a new node we know it's a leaf, so we can
	 * initialize the counts if the limit feature is active.
	 */
	if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_FS_SS_LIMIT)) {
		uint64_t cnt = 0;
		objset_t *os = dd->dd_pool->dp_meta_objset;

		dsl_dir_zapify(dd, tx);
		VERIFY0(zap_add(os, dd->dd_object, DD_FIELD_FILESYSTEM_COUNT,
		    sizeof (cnt), 1, &cnt, tx));
		VERIFY0(zap_add(os, dd->dd_object, DD_FIELD_SNAPSHOT_COUNT,
		    sizeof (cnt), 1, &cnt, tx));
	}

	dsl_dir_rele(dd, FTAG);

	/*
	 * If we are creating a clone, make sure we zero out any stale
	 * data from the origin snapshots zil header.
	 */
	if (origin != NULL && !(flags & DS_CREATE_FLAG_NODIRTY)) {
		dsl_dataset_t *ds;

		VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
		dsl_dataset_zero_zil(ds, tx);
		dsl_dataset_rele(ds, FTAG);
	}

	return (dsobj);
}

/*
 * The unique space in the head dataset can be calculated by subtracting
 * the space used in the most recent snapshot, that is still being used
 * in this file system, from the space currently in use.  To figure out
 * the space in the most recent snapshot still in use, we need to take
 * the total space used in the snapshot and subtract out the space that
 * has been freed up since the snapshot was taken.
 */
void
dsl_dataset_recalc_head_uniq(dsl_dataset_t *ds)
{
	uint64_t mrs_used;
	uint64_t dlused, dlcomp, dluncomp;

	ASSERT(!ds->ds_is_snapshot);

	if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0)
		mrs_used = dsl_dataset_phys(ds->ds_prev)->ds_referenced_bytes;
	else
		mrs_used = 0;

	dsl_deadlist_space(&ds->ds_deadlist, &dlused, &dlcomp, &dluncomp);

	ASSERT3U(dlused, <=, mrs_used);
	dsl_dataset_phys(ds)->ds_unique_bytes =
	    dsl_dataset_phys(ds)->ds_referenced_bytes - (mrs_used - dlused);

	if (spa_version(ds->ds_dir->dd_pool->dp_spa) >=
	    SPA_VERSION_UNIQUE_ACCURATE)
		dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
}

void
dsl_dataset_remove_from_next_clones(dsl_dataset_t *ds, uint64_t obj,
    dmu_tx_t *tx)
{
	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
	uint64_t count;
	int err;

	ASSERT(dsl_dataset_phys(ds)->ds_num_children >= 2);
	err = zap_remove_int(mos, dsl_dataset_phys(ds)->ds_next_clones_obj,
	    obj, tx);
	/*
	 * The err should not be ENOENT, but a bug in a previous version
	 * of the code could cause upgrade_clones_cb() to not set
	 * ds_next_snap_obj when it should, leading to a missing entry.
	 * If we knew that the pool was created after
	 * SPA_VERSION_NEXT_CLONES, we could assert that it isn't
	 * ENOENT.  However, at least we can check that we don't have
	 * too many entries in the next_clones_obj even after failing to
	 * remove this one.
	 */
	if (err != ENOENT)
		VERIFY0(err);
	ASSERT0(zap_count(mos, dsl_dataset_phys(ds)->ds_next_clones_obj,
	    &count));
	ASSERT3U(count, <=, dsl_dataset_phys(ds)->ds_num_children - 2);
}


blkptr_t *
dsl_dataset_get_blkptr(dsl_dataset_t *ds)
{
	return (&dsl_dataset_phys(ds)->ds_bp);
}

spa_t *
dsl_dataset_get_spa(dsl_dataset_t *ds)
{
	return (ds->ds_dir->dd_pool->dp_spa);
}

void
dsl_dataset_dirty(dsl_dataset_t *ds, dmu_tx_t *tx)
{
	dsl_pool_t *dp;

	if (ds == NULL) /* this is the meta-objset */
		return;

	ASSERT(ds->ds_objset != NULL);

	if (dsl_dataset_phys(ds)->ds_next_snap_obj != 0)
		panic("dirtying snapshot!");

	/* Must not dirty a dataset in the same txg where it got snapshotted. */
	ASSERT3U(tx->tx_txg, >, dsl_dataset_phys(ds)->ds_prev_snap_txg);

	dp = ds->ds_dir->dd_pool;
	if (txg_list_add(&dp->dp_dirty_datasets, ds, tx->tx_txg)) {
		objset_t *os = ds->ds_objset;

		/* up the hold count until we can be written out */
		dmu_buf_add_ref(ds->ds_dbuf, ds);

		/* if this dataset is encrypted, grab a reference to the DCK */
		if (ds->ds_dir->dd_crypto_obj != 0 &&
		    !os->os_raw_receive &&
		    !os->os_next_write_raw[tx->tx_txg & TXG_MASK]) {
			ASSERT3P(ds->ds_key_mapping, !=, NULL);
			key_mapping_add_ref(ds->ds_key_mapping, ds);
		}
	}
}

boolean_t
dsl_dataset_is_dirty(dsl_dataset_t *ds)
{
	for (int t = 0; t < TXG_SIZE; t++) {
		if (txg_list_member(&ds->ds_dir->dd_pool->dp_dirty_datasets,
		    ds, t))
			return (B_TRUE);
	}
	return (B_FALSE);
}

static int
dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
{
	uint64_t asize;

	if (!dmu_tx_is_syncing(tx))
		return (0);

	/*
	 * If there's an fs-only reservation, any blocks that might become
	 * owned by the snapshot dataset must be accommodated by space
	 * outside of the reservation.
	 */
	ASSERT(ds->ds_reserved == 0 || DS_UNIQUE_IS_ACCURATE(ds));
	asize = MIN(dsl_dataset_phys(ds)->ds_unique_bytes, ds->ds_reserved);
	if (asize > dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE))
		return (SET_ERROR(ENOSPC));

	/*
	 * Propagate any reserved space for this snapshot to other
	 * snapshot checks in this sync group.
	 */
	if (asize > 0)
		dsl_dir_willuse_space(ds->ds_dir, asize, tx);

	return (0);
}

int
dsl_dataset_snapshot_check_impl(dsl_dataset_t *ds, const char *snapname,
    dmu_tx_t *tx, boolean_t recv, uint64_t cnt, cred_t *cr)
{
	int error;
	uint64_t value;

	ds->ds_trysnap_txg = tx->tx_txg;

	if (!dmu_tx_is_syncing(tx))
		return (0);

	/*
	 * We don't allow multiple snapshots of the same txg.  If there
	 * is already one, try again.
	 */
	if (dsl_dataset_phys(ds)->ds_prev_snap_txg >= tx->tx_txg)
		return (SET_ERROR(EAGAIN));

	/*
	 * Check for conflicting snapshot name.
	 */
	error = dsl_dataset_snap_lookup(ds, snapname, &value);
	if (error == 0)
		return (SET_ERROR(EEXIST));
	if (error != ENOENT)
		return (error);

	/*
	 * We don't allow taking snapshots of inconsistent datasets, such as
	 * those into which we are currently receiving.  However, if we are
	 * creating this snapshot as part of a receive, this check will be
	 * executed atomically with respect to the completion of the receive
	 * itself but prior to the clearing of DS_FLAG_INCONSISTENT; in this
	 * case we ignore this, knowing it will be fixed up for us shortly in
	 * dmu_recv_end_sync().
	 */
	if (!recv && DS_IS_INCONSISTENT(ds))
		return (SET_ERROR(EBUSY));

	/*
	 * Skip the check for temporary snapshots or if we have already checked
	 * the counts in dsl_dataset_snapshot_check. This means we really only
	 * check the count here when we're receiving a stream.
	 */
	if (cnt != 0 && cr != NULL) {
		error = dsl_fs_ss_limit_check(ds->ds_dir, cnt,
		    ZFS_PROP_SNAPSHOT_LIMIT, NULL, cr);
		if (error != 0)
			return (error);
	}

	error = dsl_dataset_snapshot_reserve_space(ds, tx);
	if (error != 0)
		return (error);

	return (0);
}

int
dsl_dataset_snapshot_check(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_snapshot_arg_t *ddsa = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	nvpair_t *pair;
	int rv = 0;

	/*
	 * Pre-compute how many total new snapshots will be created for each
	 * level in the tree and below. This is needed for validating the
	 * snapshot limit when either taking a recursive snapshot or when
	 * taking multiple snapshots.
	 *
	 * The problem is that the counts are not actually adjusted when
	 * we are checking, only when we finally sync. For a single snapshot,
	 * this is easy, the count will increase by 1 at each node up the tree,
	 * but its more complicated for the recursive/multiple snapshot case.
	 *
	 * The dsl_fs_ss_limit_check function does recursively check the count
	 * at each level up the tree but since it is validating each snapshot
	 * independently we need to be sure that we are validating the complete
	 * count for the entire set of snapshots. We do this by rolling up the
	 * counts for each component of the name into an nvlist and then
	 * checking each of those cases with the aggregated count.
	 *
	 * This approach properly handles not only the recursive snapshot
	 * case (where we get all of those on the ddsa_snaps list) but also
	 * the sibling case (e.g. snapshot a/b and a/c so that we will also
	 * validate the limit on 'a' using a count of 2).
	 *
	 * We validate the snapshot names in the third loop and only report
	 * name errors once.
	 */
	if (dmu_tx_is_syncing(tx)) {
		nvlist_t *cnt_track = NULL;
		cnt_track = fnvlist_alloc();

		/* Rollup aggregated counts into the cnt_track list */
		for (pair = nvlist_next_nvpair(ddsa->ddsa_snaps, NULL);
		    pair != NULL;
		    pair = nvlist_next_nvpair(ddsa->ddsa_snaps, pair)) {
			char *pdelim;
			uint64_t val;
			char nm[MAXPATHLEN];

			(void) strlcpy(nm, nvpair_name(pair), sizeof (nm));
			pdelim = strchr(nm, '@');
			if (pdelim == NULL)
				continue;
			*pdelim = '\0';

			do {
				if (nvlist_lookup_uint64(cnt_track, nm,
				    &val) == 0) {
					/* update existing entry */
					fnvlist_add_uint64(cnt_track, nm,
					    val + 1);
				} else {
					/* add to list */
					fnvlist_add_uint64(cnt_track, nm, 1);
				}

				pdelim = strrchr(nm, '/');
				if (pdelim != NULL)
					*pdelim = '\0';
			} while (pdelim != NULL);
		}

		/* Check aggregated counts at each level */
		for (pair = nvlist_next_nvpair(cnt_track, NULL);
		    pair != NULL; pair = nvlist_next_nvpair(cnt_track, pair)) {
			int error = 0;
			char *name;
			uint64_t cnt = 0;
			dsl_dataset_t *ds;

			name = nvpair_name(pair);
			cnt = fnvpair_value_uint64(pair);
			ASSERT(cnt > 0);

			error = dsl_dataset_hold(dp, name, FTAG, &ds);
			if (error == 0) {
				error = dsl_fs_ss_limit_check(ds->ds_dir, cnt,
				    ZFS_PROP_SNAPSHOT_LIMIT, NULL,
				    ddsa->ddsa_cr);
				dsl_dataset_rele(ds, FTAG);
			}

			if (error != 0) {
				if (ddsa->ddsa_errors != NULL)
					fnvlist_add_int32(ddsa->ddsa_errors,
					    name, error);
				rv = error;
				/* only report one error for this check */
				break;
			}
		}
		nvlist_free(cnt_track);
	}

	for (pair = nvlist_next_nvpair(ddsa->ddsa_snaps, NULL);
	    pair != NULL; pair = nvlist_next_nvpair(ddsa->ddsa_snaps, pair)) {
		int error = 0;
		dsl_dataset_t *ds;
		char *name, *atp;
		char dsname[ZFS_MAX_DATASET_NAME_LEN];

		name = nvpair_name(pair);
		if (strlen(name) >= ZFS_MAX_DATASET_NAME_LEN)
			error = SET_ERROR(ENAMETOOLONG);
		if (error == 0) {
			atp = strchr(name, '@');
			if (atp == NULL)
				error = SET_ERROR(EINVAL);
			if (error == 0)
				(void) strlcpy(dsname, name, atp - name + 1);
		}
		if (error == 0)
			error = dsl_dataset_hold(dp, dsname, FTAG, &ds);
		if (error == 0) {
			/* passing 0/NULL skips dsl_fs_ss_limit_check */
			error = dsl_dataset_snapshot_check_impl(ds,
			    atp + 1, tx, B_FALSE, 0, NULL);
			dsl_dataset_rele(ds, FTAG);
		}

		if (error != 0) {
			if (ddsa->ddsa_errors != NULL) {
				fnvlist_add_int32(ddsa->ddsa_errors,
				    name, error);
			}
			rv = error;
		}
	}

	return (rv);
}

void
dsl_dataset_snapshot_sync_impl(dsl_dataset_t *ds, const char *snapname,
    dmu_tx_t *tx)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	dmu_buf_t *dbuf;
	dsl_dataset_phys_t *dsphys;
	uint64_t dsobj, crtxg;
	objset_t *mos = dp->dp_meta_objset;
	objset_t *os;

	ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));

	/*
	 * If we are on an old pool, the zil must not be active, in which
	 * case it will be zeroed.  Usually zil_suspend() accomplishes this.
	 */
	ASSERT(spa_version(dmu_tx_pool(tx)->dp_spa) >= SPA_VERSION_FAST_SNAP ||
	    dmu_objset_from_ds(ds, &os) != 0 ||
	    bcmp(&os->os_phys->os_zil_header, &zero_zil,
	    sizeof (zero_zil)) == 0);

	/* Should not snapshot a dirty dataset. */
	ASSERT(!txg_list_member(&ds->ds_dir->dd_pool->dp_dirty_datasets,
	    ds, tx->tx_txg));

	dsl_fs_ss_count_adjust(ds->ds_dir, 1, DD_FIELD_SNAPSHOT_COUNT, tx);

	/*
	 * The origin's ds_creation_txg has to be < TXG_INITIAL
	 */
	if (strcmp(snapname, ORIGIN_DIR_NAME) == 0)
		crtxg = 1;
	else
		crtxg = tx->tx_txg;

	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
	VERIFY0(dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
	dmu_buf_will_dirty(dbuf, tx);
	dsphys = dbuf->db_data;
	bzero(dsphys, sizeof (dsl_dataset_phys_t));
	dsphys->ds_dir_obj = ds->ds_dir->dd_object;
	dsphys->ds_fsid_guid = unique_create();
	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
	    sizeof (dsphys->ds_guid));
	dsphys->ds_prev_snap_obj = dsl_dataset_phys(ds)->ds_prev_snap_obj;
	dsphys->ds_prev_snap_txg = dsl_dataset_phys(ds)->ds_prev_snap_txg;
	dsphys->ds_next_snap_obj = ds->ds_object;
	dsphys->ds_num_children = 1;
	dsphys->ds_creation_time = gethrestime_sec();
	dsphys->ds_creation_txg = crtxg;
	dsphys->ds_deadlist_obj = dsl_dataset_phys(ds)->ds_deadlist_obj;
	dsphys->ds_referenced_bytes = dsl_dataset_phys(ds)->ds_referenced_bytes;
	dsphys->ds_compressed_bytes = dsl_dataset_phys(ds)->ds_compressed_bytes;
	dsphys->ds_uncompressed_bytes =
	    dsl_dataset_phys(ds)->ds_uncompressed_bytes;
	dsphys->ds_flags = dsl_dataset_phys(ds)->ds_flags;
	rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
	dsphys->ds_bp = dsl_dataset_phys(ds)->ds_bp;
	rrw_exit(&ds->ds_bp_rwlock, FTAG);
	dmu_buf_rele(dbuf, FTAG);

	for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
		if (ds->ds_feature_inuse[f])
			dsl_dataset_activate_feature(dsobj, f, tx);
	}

	ASSERT3U(ds->ds_prev != 0, ==,
	    dsl_dataset_phys(ds)->ds_prev_snap_obj != 0);
	if (ds->ds_prev) {
		uint64_t next_clones_obj =
		    dsl_dataset_phys(ds->ds_prev)->ds_next_clones_obj;
		ASSERT(dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj ==
		    ds->ds_object ||
		    dsl_dataset_phys(ds->ds_prev)->ds_num_children > 1);
		if (dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj ==
		    ds->ds_object) {
			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
			ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_txg, ==,
			    dsl_dataset_phys(ds->ds_prev)->ds_creation_txg);
			dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj = dsobj;
		} else if (next_clones_obj != 0) {
			dsl_dataset_remove_from_next_clones(ds->ds_prev,
			    dsphys->ds_next_snap_obj, tx);
			VERIFY0(zap_add_int(mos,
			    next_clones_obj, dsobj, tx));
		}
	}

	/*
	 * If we have a reference-reservation on this dataset, we will
	 * need to increase the amount of refreservation being charged
	 * since our unique space is going to zero.
	 */
	if (ds->ds_reserved) {
		int64_t delta;
		ASSERT(DS_UNIQUE_IS_ACCURATE(ds));
		delta = MIN(dsl_dataset_phys(ds)->ds_unique_bytes,
		    ds->ds_reserved);
		dsl_dir_diduse_space(ds->ds_dir, DD_USED_REFRSRV,
		    delta, 0, 0, tx);
	}

	dmu_buf_will_dirty(ds->ds_dbuf, tx);
	dsl_dataset_phys(ds)->ds_deadlist_obj =
	    dsl_deadlist_clone(&ds->ds_deadlist, UINT64_MAX,
	    dsl_dataset_phys(ds)->ds_prev_snap_obj, tx);
	dsl_deadlist_close(&ds->ds_deadlist);
	dsl_deadlist_open(&ds->ds_deadlist, mos,
	    dsl_dataset_phys(ds)->ds_deadlist_obj);
	dsl_deadlist_add_key(&ds->ds_deadlist,
	    dsl_dataset_phys(ds)->ds_prev_snap_txg, tx);

	if (dsl_dataset_remap_deadlist_exists(ds)) {
		uint64_t remap_deadlist_obj =
		    dsl_dataset_get_remap_deadlist_object(ds);
		/*
		 * Move the remap_deadlist to the snapshot.  The head
		 * will create a new remap deadlist on demand, from
		 * dsl_dataset_block_remapped().
		 */
		dsl_dataset_unset_remap_deadlist_object(ds, tx);
		dsl_deadlist_close(&ds->ds_remap_deadlist);

		dmu_object_zapify(mos, dsobj, DMU_OT_DSL_DATASET, tx);
		VERIFY0(zap_add(mos, dsobj, DS_FIELD_REMAP_DEADLIST,
		    sizeof (remap_deadlist_obj), 1, &remap_deadlist_obj, tx));
	}

	/*
	 * Create a ivset guid for this snapshot if the dataset is
	 * encrypted. This may be overridden by a raw receive. A
	 * previous implementation of this code did not have this
	 * field as part of the on-disk format for ZFS encryption
	 * (see errata #4). As part of the remediation for this
	 * issue, we ask the user to enable the bookmark_v2 feature
	 * which is now a dependency of the encryption feature. We
	 * use this as a heuristic to determine when the user has
	 * elected to correct any datasets created with the old code.
	 * As a result, we only do this step if the bookmark_v2
	 * feature is enabled, which limits the number of states a
	 * given pool / dataset can be in with regards to terms of
	 * correcting the issue.
	 */
	if (ds->ds_dir->dd_crypto_obj != 0 &&
	    spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_BOOKMARK_V2)) {
		uint64_t ivset_guid = unique_create();

		dmu_object_zapify(mos, dsobj, DMU_OT_DSL_DATASET, tx);
		VERIFY0(zap_add(mos, dsobj, DS_FIELD_IVSET_GUID,
		    sizeof (ivset_guid), 1, &ivset_guid, tx));
	}

	ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_txg, <, tx->tx_txg);
	dsl_dataset_phys(ds)->ds_prev_snap_obj = dsobj;
	dsl_dataset_phys(ds)->ds_prev_snap_txg = crtxg;
	dsl_dataset_phys(ds)->ds_unique_bytes = 0;

	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
		dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;

	VERIFY0(zap_add(mos, dsl_dataset_phys(ds)->ds_snapnames_zapobj,
	    snapname, 8, 1, &dsobj, tx));

	if (ds->ds_prev)
		dsl_dataset_rele(ds->ds_prev, ds);
	VERIFY0(dsl_dataset_hold_obj(dp,
	    dsl_dataset_phys(ds)->ds_prev_snap_obj, ds, &ds->ds_prev));

	dsl_scan_ds_snapshotted(ds, tx);

	dsl_dir_snap_cmtime_update(ds->ds_dir);

	spa_history_log_internal_ds(ds->ds_prev, "snapshot", tx, "");
}

void
dsl_dataset_snapshot_sync(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_snapshot_arg_t *ddsa = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	nvpair_t *pair;

	for (pair = nvlist_next_nvpair(ddsa->ddsa_snaps, NULL);
	    pair != NULL; pair = nvlist_next_nvpair(ddsa->ddsa_snaps, pair)) {
		dsl_dataset_t *ds;
		char *name, *atp;
		char dsname[ZFS_MAX_DATASET_NAME_LEN];

		name = nvpair_name(pair);
		atp = strchr(name, '@');
		(void) strlcpy(dsname, name, atp - name + 1);
		VERIFY0(dsl_dataset_hold(dp, dsname, FTAG, &ds));

		dsl_dataset_snapshot_sync_impl(ds, atp + 1, tx);
		if (ddsa->ddsa_props != NULL) {
			dsl_props_set_sync_impl(ds->ds_prev,
			    ZPROP_SRC_LOCAL, ddsa->ddsa_props, tx);
		}
		dsl_dataset_rele(ds, FTAG);
	}
}

/*
 * The snapshots must all be in the same pool.
 * All-or-nothing: if there are any failures, nothing will be modified.
 */
int
dsl_dataset_snapshot(nvlist_t *snaps, nvlist_t *props, nvlist_t *errors)
{
	dsl_dataset_snapshot_arg_t ddsa;
	nvpair_t *pair;
	boolean_t needsuspend;
	int error;
	spa_t *spa;
	char *firstname;
	nvlist_t *suspended = NULL;

	pair = nvlist_next_nvpair(snaps, NULL);
	if (pair == NULL)
		return (0);
	firstname = nvpair_name(pair);

	error = spa_open(firstname, &spa, FTAG);
	if (error != 0)
		return (error);
	needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
	spa_close(spa, FTAG);

	if (needsuspend) {
		suspended = fnvlist_alloc();
		for (pair = nvlist_next_nvpair(snaps, NULL); pair != NULL;
		    pair = nvlist_next_nvpair(snaps, pair)) {
			char fsname[ZFS_MAX_DATASET_NAME_LEN];
			char *snapname = nvpair_name(pair);
			char *atp;
			void *cookie;

			atp = strchr(snapname, '@');
			if (atp == NULL) {
				error = SET_ERROR(EINVAL);
				break;
			}
			(void) strlcpy(fsname, snapname, atp - snapname + 1);

			error = zil_suspend(fsname, &cookie);
			if (error != 0)
				break;
			fnvlist_add_uint64(suspended, fsname,
			    (uintptr_t)cookie);
		}
	}

	ddsa.ddsa_snaps = snaps;
	ddsa.ddsa_props = props;
	ddsa.ddsa_errors = errors;
	ddsa.ddsa_cr = CRED();

	if (error == 0) {
		error = dsl_sync_task(firstname, dsl_dataset_snapshot_check,
		    dsl_dataset_snapshot_sync, &ddsa,
		    fnvlist_num_pairs(snaps) * 3, ZFS_SPACE_CHECK_NORMAL);
	}

	if (suspended != NULL) {
		for (pair = nvlist_next_nvpair(suspended, NULL); pair != NULL;
		    pair = nvlist_next_nvpair(suspended, pair)) {
			zil_resume((void *)(uintptr_t)
			    fnvpair_value_uint64(pair));
		}
		fnvlist_free(suspended);
	}

	return (error);
}

typedef struct dsl_dataset_snapshot_tmp_arg {
	const char *ddsta_fsname;
	const char *ddsta_snapname;
	minor_t ddsta_cleanup_minor;
	const char *ddsta_htag;
} dsl_dataset_snapshot_tmp_arg_t;

static int
dsl_dataset_snapshot_tmp_check(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_snapshot_tmp_arg_t *ddsta = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	dsl_dataset_t *ds;
	int error;

	error = dsl_dataset_hold(dp, ddsta->ddsta_fsname, FTAG, &ds);
	if (error != 0)
		return (error);

	/* NULL cred means no limit check for tmp snapshot */
	error = dsl_dataset_snapshot_check_impl(ds, ddsta->ddsta_snapname,
	    tx, B_FALSE, 0, NULL);
	if (error != 0) {
		dsl_dataset_rele(ds, FTAG);
		return (error);
	}

	if (spa_version(dp->dp_spa) < SPA_VERSION_USERREFS) {
		dsl_dataset_rele(ds, FTAG);
		return (SET_ERROR(ENOTSUP));
	}
	error = dsl_dataset_user_hold_check_one(NULL, ddsta->ddsta_htag,
	    B_TRUE, tx);
	if (error != 0) {
		dsl_dataset_rele(ds, FTAG);
		return (error);
	}

	dsl_dataset_rele(ds, FTAG);
	return (0);
}

static void
dsl_dataset_snapshot_tmp_sync(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_snapshot_tmp_arg_t *ddsta = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	dsl_dataset_t *ds;

	VERIFY0(dsl_dataset_hold(dp, ddsta->ddsta_fsname, FTAG, &ds));

	dsl_dataset_snapshot_sync_impl(ds, ddsta->ddsta_snapname, tx);
	dsl_dataset_user_hold_sync_one(ds->ds_prev, ddsta->ddsta_htag,
	    ddsta->ddsta_cleanup_minor, gethrestime_sec(), tx);
	dsl_destroy_snapshot_sync_impl(ds->ds_prev, B_TRUE, tx);

	dsl_dataset_rele(ds, FTAG);
}

int
dsl_dataset_snapshot_tmp(const char *fsname, const char *snapname,
    minor_t cleanup_minor, const char *htag)
{
	dsl_dataset_snapshot_tmp_arg_t ddsta;
	int error;
	spa_t *spa;
	boolean_t needsuspend;
	void *cookie;

	ddsta.ddsta_fsname = fsname;
	ddsta.ddsta_snapname = snapname;
	ddsta.ddsta_cleanup_minor = cleanup_minor;
	ddsta.ddsta_htag = htag;

	error = spa_open(fsname, &spa, FTAG);
	if (error != 0)
		return (error);
	needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
	spa_close(spa, FTAG);

	if (needsuspend) {
		error = zil_suspend(fsname, &cookie);
		if (error != 0)
			return (error);
	}

	error = dsl_sync_task(fsname, dsl_dataset_snapshot_tmp_check,
	    dsl_dataset_snapshot_tmp_sync, &ddsta, 3, ZFS_SPACE_CHECK_RESERVED);

	if (needsuspend)
		zil_resume(cookie);
	return (error);
}

void
dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
{
	ASSERT(dmu_tx_is_syncing(tx));
	ASSERT(ds->ds_objset != NULL);
	ASSERT(dsl_dataset_phys(ds)->ds_next_snap_obj == 0);

	/*
	 * in case we had to change ds_fsid_guid when we opened it,
	 * sync it out now.
	 */
	dmu_buf_will_dirty(ds->ds_dbuf, tx);
	dsl_dataset_phys(ds)->ds_fsid_guid = ds->ds_fsid_guid;

	if (ds->ds_resume_bytes[tx->tx_txg & TXG_MASK] != 0) {
		VERIFY0(zap_update(tx->tx_pool->dp_meta_objset,
		    ds->ds_object, DS_FIELD_RESUME_OBJECT, 8, 1,
		    &ds->ds_resume_object[tx->tx_txg & TXG_MASK], tx));
		VERIFY0(zap_update(tx->tx_pool->dp_meta_objset,
		    ds->ds_object, DS_FIELD_RESUME_OFFSET, 8, 1,
		    &ds->ds_resume_offset[tx->tx_txg & TXG_MASK], tx));
		VERIFY0(zap_update(tx->tx_pool->dp_meta_objset,
		    ds->ds_object, DS_FIELD_RESUME_BYTES, 8, 1,
		    &ds->ds_resume_bytes[tx->tx_txg & TXG_MASK], tx));
		ds->ds_resume_object[tx->tx_txg & TXG_MASK] = 0;
		ds->ds_resume_offset[tx->tx_txg & TXG_MASK] = 0;
		ds->ds_resume_bytes[tx->tx_txg & TXG_MASK] = 0;
	}

	dmu_objset_sync(ds->ds_objset, zio, tx);

	for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
		if (ds->ds_feature_activation_needed[f]) {
			if (ds->ds_feature_inuse[f])
				continue;
			dsl_dataset_activate_feature(ds->ds_object, f, tx);
			ds->ds_feature_inuse[f] = B_TRUE;
		}
	}
}

static int
deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
{
	dsl_deadlist_t *dl = arg;
	dsl_deadlist_insert(dl, bp, tx);
	return (0);
}

void
dsl_dataset_sync_done(dsl_dataset_t *ds, dmu_tx_t *tx)
{
	objset_t *os = ds->ds_objset;

	bplist_iterate(&ds->ds_pending_deadlist,
	    deadlist_enqueue_cb, &ds->ds_deadlist, tx);

	if (os->os_synced_dnodes != NULL) {
		multilist_destroy(os->os_synced_dnodes);
		os->os_synced_dnodes = NULL;
	}

	if (os->os_encrypted)
		os->os_next_write_raw[tx->tx_txg & TXG_MASK] = B_FALSE;
	else
		ASSERT0(os->os_next_write_raw[tx->tx_txg & TXG_MASK]);

	ASSERT(!dmu_objset_is_dirty(os, dmu_tx_get_txg(tx)));

	dmu_buf_rele(ds->ds_dbuf, ds);
}

int
get_clones_stat_impl(dsl_dataset_t *ds, nvlist_t *val)
{
	uint64_t count = 0;
	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
	zap_cursor_t zc;
	zap_attribute_t za;

	ASSERT(dsl_pool_config_held(ds->ds_dir->dd_pool));

	/*
	 * There may be missing entries in ds_next_clones_obj
	 * due to a bug in a previous version of the code.
	 * Only trust it if it has the right number of entries.
	 */
	if (dsl_dataset_phys(ds)->ds_next_clones_obj != 0) {
		VERIFY0(zap_count(mos, dsl_dataset_phys(ds)->ds_next_clones_obj,
		    &count));
	}
	if (count != dsl_dataset_phys(ds)->ds_num_children - 1) {
		return (ENOENT);
	}
	for (zap_cursor_init(&zc, mos,
	    dsl_dataset_phys(ds)->ds_next_clones_obj);
	    zap_cursor_retrieve(&zc, &za) == 0;
	    zap_cursor_advance(&zc)) {
		dsl_dataset_t *clone;
		char buf[ZFS_MAX_DATASET_NAME_LEN];
		VERIFY0(dsl_dataset_hold_obj(ds->ds_dir->dd_pool,
		    za.za_first_integer, FTAG, &clone));
		dsl_dir_name(clone->ds_dir, buf);
		fnvlist_add_boolean(val, buf);
		dsl_dataset_rele(clone, FTAG);
	}
	zap_cursor_fini(&zc);
	return (0);
}

void
get_clones_stat(dsl_dataset_t *ds, nvlist_t *nv)
{
	nvlist_t *propval = fnvlist_alloc();
	nvlist_t *val;

	/*
	 * We use nvlist_alloc() instead of fnvlist_alloc() because the
	 * latter would allocate the list with NV_UNIQUE_NAME flag.
	 * As a result, every time a clone name is appended to the list
	 * it would be (linearly) searched for for a duplicate name.
	 * We already know that all clone names must be unique and we
	 * want avoid the quadratic complexity of double-checking that
	 * because we can have a large number of clones.
	 */
	VERIFY0(nvlist_alloc(&val, 0, KM_SLEEP));

	if (get_clones_stat_impl(ds, val) == 0) {
		fnvlist_add_nvlist(propval, ZPROP_VALUE, val);
		fnvlist_add_nvlist(nv, zfs_prop_to_name(ZFS_PROP_CLONES),
		    propval);
	}

	nvlist_free(val);
	nvlist_free(propval);
}

/*
 * Returns a string that represents the receive resume stats token. It should
 * be freed with strfree().
 */
char *
get_receive_resume_stats_impl(dsl_dataset_t *ds)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;

	if (dsl_dataset_has_resume_receive_state(ds)) {
		char *str;
		void *packed;
		uint8_t *compressed;
		uint64_t val;
		nvlist_t *token_nv = fnvlist_alloc();
		size_t packed_size, compressed_size;

		if (zap_lookup(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_FROMGUID, sizeof (val), 1, &val) == 0) {
			fnvlist_add_uint64(token_nv, "fromguid", val);
		}
		if (zap_lookup(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_OBJECT, sizeof (val), 1, &val) == 0) {
			fnvlist_add_uint64(token_nv, "object", val);
		}
		if (zap_lookup(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_OFFSET, sizeof (val), 1, &val) == 0) {
			fnvlist_add_uint64(token_nv, "offset", val);
		}
		if (zap_lookup(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_BYTES, sizeof (val), 1, &val) == 0) {
			fnvlist_add_uint64(token_nv, "bytes", val);
		}
		if (zap_lookup(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_TOGUID, sizeof (val), 1, &val) == 0) {
			fnvlist_add_uint64(token_nv, "toguid", val);
		}
		char buf[256];
		if (zap_lookup(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_TONAME, 1, sizeof (buf), buf) == 0) {
			fnvlist_add_string(token_nv, "toname", buf);
		}
		if (zap_contains(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_LARGEBLOCK) == 0) {
			fnvlist_add_boolean(token_nv, "largeblockok");
		}
		if (zap_contains(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_EMBEDOK) == 0) {
			fnvlist_add_boolean(token_nv, "embedok");
		}
		if (zap_contains(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_COMPRESSOK) == 0) {
			fnvlist_add_boolean(token_nv, "compressok");
		}
		if (zap_contains(dp->dp_meta_objset, ds->ds_object,
		    DS_FIELD_RESUME_RAWOK) == 0) {
			fnvlist_add_boolean(token_nv, "rawok");
		}
		packed = fnvlist_pack(token_nv, &packed_size);
		fnvlist_free(token_nv);
		compressed = kmem_alloc(packed_size, KM_SLEEP);

		compressed_size = gzip_compress(packed, compressed,
		    packed_size, packed_size, 6);

		zio_cksum_t cksum;
		fletcher_4_native(compressed, compressed_size, NULL, &cksum);

		str = kmem_alloc(compressed_size * 2 + 1, KM_SLEEP);
		for (int i = 0; i < compressed_size; i++) {
			(void) sprintf(str + i * 2, "%02x", compressed[i]);
		}
		str[compressed_size * 2] = '\0';
		char *propval = kmem_asprintf("%u-%llx-%llx-%s",
		    ZFS_SEND_RESUME_TOKEN_VERSION,
		    (longlong_t)cksum.zc_word[0],
		    (longlong_t)packed_size, str);
		kmem_free(packed, packed_size);
		kmem_free(str, compressed_size * 2 + 1);
		kmem_free(compressed, packed_size);
		return (propval);
	}
	return (strdup(""));
}

/*
 * Returns a string that represents the receive resume stats token of the
 * dataset's child. It should be freed with strfree().
 */
char *
get_child_receive_stats(dsl_dataset_t *ds)
{
	char recvname[ZFS_MAX_DATASET_NAME_LEN + 6];
	dsl_dataset_t *recv_ds;
	dsl_dataset_name(ds, recvname);
	if (strlcat(recvname, "/", sizeof (recvname)) <
	    sizeof (recvname) &&
	    strlcat(recvname, recv_clone_name, sizeof (recvname)) <
	    sizeof (recvname) &&
	    dsl_dataset_hold(ds->ds_dir->dd_pool, recvname, FTAG,
	    &recv_ds)  == 0) {
		char *propval = get_receive_resume_stats_impl(recv_ds);
		dsl_dataset_rele(recv_ds, FTAG);
		return (propval);
	}
	return (strdup(""));
}

static void
get_receive_resume_stats(dsl_dataset_t *ds, nvlist_t *nv)
{
	char *propval = get_receive_resume_stats_impl(ds);
	if (strcmp(propval, "") != 0) {
		dsl_prop_nvlist_add_string(nv,
		    ZFS_PROP_RECEIVE_RESUME_TOKEN, propval);
	} else {
		char *childval = get_child_receive_stats(ds);
		if (strcmp(childval, "") != 0) {
			dsl_prop_nvlist_add_string(nv,
			    ZFS_PROP_RECEIVE_RESUME_TOKEN, childval);
		}
		strfree(childval);
	}
	strfree(propval);
}

uint64_t
dsl_get_refratio(dsl_dataset_t *ds)
{
	uint64_t ratio = dsl_dataset_phys(ds)->ds_compressed_bytes == 0 ? 100 :
	    (dsl_dataset_phys(ds)->ds_uncompressed_bytes * 100 /
	    dsl_dataset_phys(ds)->ds_compressed_bytes);
	return (ratio);
}

uint64_t
dsl_get_logicalreferenced(dsl_dataset_t *ds)
{
	return (dsl_dataset_phys(ds)->ds_uncompressed_bytes);
}

uint64_t
dsl_get_compressratio(dsl_dataset_t *ds)
{
	if (ds->ds_is_snapshot) {
		return (dsl_get_refratio(ds));
	} else {
		dsl_dir_t *dd = ds->ds_dir;
		mutex_enter(&dd->dd_lock);
		uint64_t val = dsl_dir_get_compressratio(dd);
		mutex_exit(&dd->dd_lock);
		return (val);
	}
}

uint64_t
dsl_get_used(dsl_dataset_t *ds)
{
	if (ds->ds_is_snapshot) {
		return (dsl_dataset_phys(ds)->ds_unique_bytes);
	} else {
		dsl_dir_t *dd = ds->ds_dir;
		mutex_enter(&dd->dd_lock);
		uint64_t val = dsl_dir_get_used(dd);
		mutex_exit(&dd->dd_lock);
		return (val);
	}
}

uint64_t
dsl_get_creation(dsl_dataset_t *ds)
{
	return (dsl_dataset_phys(ds)->ds_creation_time);
}

uint64_t
dsl_get_creationtxg(dsl_dataset_t *ds)
{
	return (dsl_dataset_phys(ds)->ds_creation_txg);
}

uint64_t
dsl_get_refquota(dsl_dataset_t *ds)
{
	return (ds->ds_quota);
}

uint64_t
dsl_get_refreservation(dsl_dataset_t *ds)
{
	return (ds->ds_reserved);
}

uint64_t
dsl_get_guid(dsl_dataset_t *ds)
{
	return (dsl_dataset_phys(ds)->ds_guid);
}

uint64_t
dsl_get_unique(dsl_dataset_t *ds)
{
	return (dsl_dataset_phys(ds)->ds_unique_bytes);
}

uint64_t
dsl_get_objsetid(dsl_dataset_t *ds)
{
	return (ds->ds_object);
}

uint64_t
dsl_get_userrefs(dsl_dataset_t *ds)
{
	return (ds->ds_userrefs);
}

uint64_t
dsl_get_defer_destroy(dsl_dataset_t *ds)
{
	return (DS_IS_DEFER_DESTROY(ds) ? 1 : 0);
}

uint64_t
dsl_get_referenced(dsl_dataset_t *ds)
{
	return (dsl_dataset_phys(ds)->ds_referenced_bytes);
}

uint64_t
dsl_get_numclones(dsl_dataset_t *ds)
{
	ASSERT(ds->ds_is_snapshot);
	return (dsl_dataset_phys(ds)->ds_num_children - 1);
}

uint64_t
dsl_get_inconsistent(dsl_dataset_t *ds)
{
	return ((dsl_dataset_phys(ds)->ds_flags & DS_FLAG_INCONSISTENT) ?
	    1 : 0);
}

uint64_t
dsl_get_available(dsl_dataset_t *ds)
{
	uint64_t refdbytes = dsl_get_referenced(ds);
	uint64_t availbytes = dsl_dir_space_available(ds->ds_dir,
	    NULL, 0, TRUE);
	if (ds->ds_reserved > dsl_dataset_phys(ds)->ds_unique_bytes) {
		availbytes +=
		    ds->ds_reserved - dsl_dataset_phys(ds)->ds_unique_bytes;
	}
	if (ds->ds_quota != 0) {
		/*
		 * Adjust available bytes according to refquota
		 */
		if (refdbytes < ds->ds_quota) {
			availbytes = MIN(availbytes,
			    ds->ds_quota - refdbytes);
		} else {
			availbytes = 0;
		}
	}
	return (availbytes);
}

int
dsl_get_written(dsl_dataset_t *ds, uint64_t *written)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	dsl_dataset_t *prev;
	int err = dsl_dataset_hold_obj(dp,
	    dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
	if (err == 0) {
		uint64_t comp, uncomp;
		err = dsl_dataset_space_written(prev, ds, written,
		    &comp, &uncomp);
		dsl_dataset_rele(prev, FTAG);
	}
	return (err);
}

/*
 * 'snap' should be a buffer of size ZFS_MAX_DATASET_NAME_LEN.
 */
int
dsl_get_prev_snap(dsl_dataset_t *ds, char *snap)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	if (ds->ds_prev != NULL && ds->ds_prev != dp->dp_origin_snap) {
		dsl_dataset_name(ds->ds_prev, snap);
		return (0);
	} else {
		return (ENOENT);
	}
}

/*
 * Returns the mountpoint property and source for the given dataset in the value
 * and source buffers. The value buffer must be at least as large as MAXPATHLEN
 * and the source buffer as least as large a ZFS_MAX_DATASET_NAME_LEN.
 * Returns 0 on success and an error on failure.
 */
int
dsl_get_mountpoint(dsl_dataset_t *ds, const char *dsname, char *value,
    char *source)
{
	int error;
	dsl_pool_t *dp = ds->ds_dir->dd_pool;

	/* Retrieve the mountpoint value stored in the zap opbject */
	error = dsl_prop_get_ds(ds, zfs_prop_to_name(ZFS_PROP_MOUNTPOINT), 1,
	    ZAP_MAXVALUELEN, value, source);
	if (error != 0) {
		return (error);
	}

	/*
	 * Process the dsname and source to find the full mountpoint string.
	 * Can be skipped for 'legacy' or 'none'.
	 */
	if (value[0] == '/') {
		char *buf = kmem_alloc(ZAP_MAXVALUELEN, KM_SLEEP);
		char *root = buf;
		const char *relpath;

		/*
		 * If we inherit the mountpoint, even from a dataset
		 * with a received value, the source will be the path of
		 * the dataset we inherit from. If source is
		 * ZPROP_SOURCE_VAL_RECVD, the received value is not
		 * inherited.
		 */
		if (strcmp(source, ZPROP_SOURCE_VAL_RECVD) == 0) {
			relpath = "";
		} else {
			ASSERT0(strncmp(dsname, source, strlen(source)));
			relpath = dsname + strlen(source);
			if (relpath[0] == '/')
				relpath++;
		}

		spa_altroot(dp->dp_spa, root, ZAP_MAXVALUELEN);

		/*
		 * Special case an alternate root of '/'. This will
		 * avoid having multiple leading slashes in the
		 * mountpoint path.
		 */
		if (strcmp(root, "/") == 0)
			root++;

		/*
		 * If the mountpoint is '/' then skip over this
		 * if we are obtaining either an alternate root or
		 * an inherited mountpoint.
		 */
		char *mnt = value;
		if (value[1] == '\0' && (root[0] != '\0' ||
		    relpath[0] != '\0'))
			mnt = value + 1;

		if (relpath[0] == '\0') {
			(void) snprintf(value, ZAP_MAXVALUELEN, "%s%s",
			    root, mnt);
		} else {
			(void) snprintf(value, ZAP_MAXVALUELEN, "%s%s%s%s",
			    root, mnt, relpath[0] == '@' ? "" : "/",
			    relpath);
		}
		kmem_free(buf, ZAP_MAXVALUELEN);
	}

	return (0);
}

void
dsl_dataset_stats(dsl_dataset_t *ds, nvlist_t *nv)
{
	int err;
	dsl_pool_t *dp = ds->ds_dir->dd_pool;

	ASSERT(dsl_pool_config_held(dp));

	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFRATIO,
	    dsl_get_refratio(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_LOGICALREFERENCED,
	    dsl_get_logicalreferenced(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
	    dsl_get_compressratio(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
	    dsl_get_used(ds));

	if (ds->ds_is_snapshot) {
		get_clones_stat(ds, nv);
	} else {
		char buf[ZFS_MAX_DATASET_NAME_LEN];
		if (dsl_get_prev_snap(ds, buf) == 0)
			dsl_prop_nvlist_add_string(nv, ZFS_PROP_PREV_SNAP,
			    buf);
		dsl_dir_stats(ds->ds_dir, nv);
	}

	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_AVAILABLE,
	    dsl_get_available(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFERENCED,
	    dsl_get_referenced(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATION,
	    dsl_get_creation(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATETXG,
	    dsl_get_creationtxg(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFQUOTA,
	    dsl_get_refquota(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFRESERVATION,
	    dsl_get_refreservation(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_GUID,
	    dsl_get_guid(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_UNIQUE,
	    dsl_get_unique(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_OBJSETID,
	    dsl_get_objsetid(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERREFS,
	    dsl_get_userrefs(ds));
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_DEFER_DESTROY,
	    DS_IS_DEFER_DESTROY(ds) ? 1 : 0);
	dsl_dataset_crypt_stats(ds, nv);

	if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
		uint64_t written, comp, uncomp;
		dsl_pool_t *dp = ds->ds_dir->dd_pool;
		dsl_dataset_t *prev;

		err = dsl_dataset_hold_obj(dp,
		    dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
		if (err == 0) {
			err = dsl_dataset_space_written(prev, ds, &written,
			    &comp, &uncomp);
			dsl_dataset_rele(prev, FTAG);
			if (err == 0) {
				dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_WRITTEN,
				    written);
			}
		}
	}

	if (!dsl_dataset_is_snapshot(ds)) {
		/*
		 * A failed "newfs" (e.g. full) resumable receive leaves
		 * the stats set on this dataset.  Check here for the prop.
		 */
		get_receive_resume_stats(ds, nv);

		/*
		 * A failed incremental resumable receive leaves the
		 * stats set on our child named "%recv".  Check the child
		 * for the prop.
		 */
		/* 6 extra bytes for /%recv */
		char recvname[ZFS_MAX_DATASET_NAME_LEN + 6];
		dsl_dataset_t *recv_ds;
		dsl_dataset_name(ds, recvname);
		if (strlcat(recvname, "/", sizeof (recvname)) <
		    sizeof (recvname) &&
		    strlcat(recvname, recv_clone_name, sizeof (recvname)) <
		    sizeof (recvname) &&
		    dsl_dataset_hold(dp, recvname, FTAG, &recv_ds) == 0) {
			get_receive_resume_stats(recv_ds, nv);
			dsl_dataset_rele(recv_ds, FTAG);
		}
	}
}

void
dsl_dataset_fast_stat(dsl_dataset_t *ds, dmu_objset_stats_t *stat)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	ASSERT(dsl_pool_config_held(dp));

	stat->dds_creation_txg = dsl_get_creationtxg(ds);
	stat->dds_inconsistent = dsl_get_inconsistent(ds);
	stat->dds_guid = dsl_get_guid(ds);
	stat->dds_origin[0] = '\0';
	if (ds->ds_is_snapshot) {
		stat->dds_is_snapshot = B_TRUE;
		stat->dds_num_clones = dsl_get_numclones(ds);
	} else {
		stat->dds_is_snapshot = B_FALSE;
		stat->dds_num_clones = 0;

		if (dsl_dir_is_clone(ds->ds_dir)) {
			dsl_dir_get_origin(ds->ds_dir, stat->dds_origin);
		}
	}
}

uint64_t
dsl_dataset_fsid_guid(dsl_dataset_t *ds)
{
	return (ds->ds_fsid_guid);
}

void
dsl_dataset_space(dsl_dataset_t *ds,
    uint64_t *refdbytesp, uint64_t *availbytesp,
    uint64_t *usedobjsp, uint64_t *availobjsp)
{
	*refdbytesp = dsl_dataset_phys(ds)->ds_referenced_bytes;
	*availbytesp = dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE);
	if (ds->ds_reserved > dsl_dataset_phys(ds)->ds_unique_bytes)
		*availbytesp +=
		    ds->ds_reserved - dsl_dataset_phys(ds)->ds_unique_bytes;
	if (ds->ds_quota != 0) {
		/*
		 * Adjust available bytes according to refquota
		 */
		if (*refdbytesp < ds->ds_quota)
			*availbytesp = MIN(*availbytesp,
			    ds->ds_quota - *refdbytesp);
		else
			*availbytesp = 0;
	}
	rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
	*usedobjsp = BP_GET_FILL(&dsl_dataset_phys(ds)->ds_bp);
	rrw_exit(&ds->ds_bp_rwlock, FTAG);
	*availobjsp = DN_MAX_OBJECT - *usedobjsp;
}

boolean_t
dsl_dataset_modified_since_snap(dsl_dataset_t *ds, dsl_dataset_t *snap)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	uint64_t birth;

	ASSERT(dsl_pool_config_held(dp));
	if (snap == NULL)
		return (B_FALSE);
	rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
	birth = dsl_dataset_get_blkptr(ds)->blk_birth;
	rrw_exit(&ds->ds_bp_rwlock, FTAG);
	if (birth > dsl_dataset_phys(snap)->ds_creation_txg) {
		objset_t *os, *os_snap;
		/*
		 * It may be that only the ZIL differs, because it was
		 * reset in the head.  Don't count that as being
		 * modified.
		 */
		if (dmu_objset_from_ds(ds, &os) != 0)
			return (B_TRUE);
		if (dmu_objset_from_ds(snap, &os_snap) != 0)
			return (B_TRUE);
		return (bcmp(&os->os_phys->os_meta_dnode,
		    &os_snap->os_phys->os_meta_dnode,
		    sizeof (os->os_phys->os_meta_dnode)) != 0);
	}
	return (B_FALSE);
}

typedef struct dsl_dataset_rename_snapshot_arg {
	const char *ddrsa_fsname;
	const char *ddrsa_oldsnapname;
	const char *ddrsa_newsnapname;
	boolean_t ddrsa_recursive;
	dmu_tx_t *ddrsa_tx;
} dsl_dataset_rename_snapshot_arg_t;

/* ARGSUSED */
static int
dsl_dataset_rename_snapshot_check_impl(dsl_pool_t *dp,
    dsl_dataset_t *hds, void *arg)
{
	dsl_dataset_rename_snapshot_arg_t *ddrsa = arg;
	int error;
	uint64_t val;

	error = dsl_dataset_snap_lookup(hds, ddrsa->ddrsa_oldsnapname, &val);
	if (error != 0) {
		/* ignore nonexistent snapshots */
		return (error == ENOENT ? 0 : error);
	}

	/* new name should not exist */
	error = dsl_dataset_snap_lookup(hds, ddrsa->ddrsa_newsnapname, &val);
	if (error == 0)
		error = SET_ERROR(EEXIST);
	else if (error == ENOENT)
		error = 0;

	/* dataset name + 1 for the "@" + the new snapshot name must fit */
	if (dsl_dir_namelen(hds->ds_dir) + 1 +
	    strlen(ddrsa->ddrsa_newsnapname) >= ZFS_MAX_DATASET_NAME_LEN)
		error = SET_ERROR(ENAMETOOLONG);

	return (error);
}

static int
dsl_dataset_rename_snapshot_check(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_rename_snapshot_arg_t *ddrsa = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	dsl_dataset_t *hds;
	int error;

	error = dsl_dataset_hold(dp, ddrsa->ddrsa_fsname, FTAG, &hds);
	if (error != 0)
		return (error);

	if (ddrsa->ddrsa_recursive) {
		error = dmu_objset_find_dp(dp, hds->ds_dir->dd_object,
		    dsl_dataset_rename_snapshot_check_impl, ddrsa,
		    DS_FIND_CHILDREN);
	} else {
		error = dsl_dataset_rename_snapshot_check_impl(dp, hds, ddrsa);
	}
	dsl_dataset_rele(hds, FTAG);
	return (error);
}

static int
dsl_dataset_rename_snapshot_sync_impl(dsl_pool_t *dp,
    dsl_dataset_t *hds, void *arg)
{
	dsl_dataset_rename_snapshot_arg_t *ddrsa = arg;
	dsl_dataset_t *ds;
	uint64_t val;
	dmu_tx_t *tx = ddrsa->ddrsa_tx;
	int error;

	error = dsl_dataset_snap_lookup(hds, ddrsa->ddrsa_oldsnapname, &val);
	ASSERT(error == 0 || error == ENOENT);
	if (error == ENOENT) {
		/* ignore nonexistent snapshots */
		return (0);
	}

	VERIFY0(dsl_dataset_hold_obj(dp, val, FTAG, &ds));

	/* log before we change the name */
	spa_history_log_internal_ds(ds, "rename", tx,
	    "-> @%s", ddrsa->ddrsa_newsnapname);

	VERIFY0(dsl_dataset_snap_remove(hds, ddrsa->ddrsa_oldsnapname, tx,
	    B_FALSE));
	mutex_enter(&ds->ds_lock);
	(void) strcpy(ds->ds_snapname, ddrsa->ddrsa_newsnapname);
	mutex_exit(&ds->ds_lock);
	VERIFY0(zap_add(dp->dp_meta_objset,
	    dsl_dataset_phys(hds)->ds_snapnames_zapobj,
	    ds->ds_snapname, 8, 1, &ds->ds_object, tx));

	dsl_dataset_rele(ds, FTAG);
	return (0);
}

static void
dsl_dataset_rename_snapshot_sync(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_rename_snapshot_arg_t *ddrsa = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	dsl_dataset_t *hds;

	VERIFY0(dsl_dataset_hold(dp, ddrsa->ddrsa_fsname, FTAG, &hds));
	ddrsa->ddrsa_tx = tx;
	if (ddrsa->ddrsa_recursive) {
		VERIFY0(dmu_objset_find_dp(dp, hds->ds_dir->dd_object,
		    dsl_dataset_rename_snapshot_sync_impl, ddrsa,
		    DS_FIND_CHILDREN));
	} else {
		VERIFY0(dsl_dataset_rename_snapshot_sync_impl(dp, hds, ddrsa));
	}
	dsl_dataset_rele(hds, FTAG);
}

int
dsl_dataset_rename_snapshot(const char *fsname,
    const char *oldsnapname, const char *newsnapname, boolean_t recursive)
{
	dsl_dataset_rename_snapshot_arg_t ddrsa;

	ddrsa.ddrsa_fsname = fsname;
	ddrsa.ddrsa_oldsnapname = oldsnapname;
	ddrsa.ddrsa_newsnapname = newsnapname;
	ddrsa.ddrsa_recursive = recursive;

	return (dsl_sync_task(fsname, dsl_dataset_rename_snapshot_check,
	    dsl_dataset_rename_snapshot_sync, &ddrsa,
	    1, ZFS_SPACE_CHECK_RESERVED));
}

/*
 * If we're doing an ownership handoff, we need to make sure that there is
 * only one long hold on the dataset.  We're not allowed to change anything here
 * so we don't permanently release the long hold or regular hold here.  We want
 * to do this only when syncing to avoid the dataset unexpectedly going away
 * when we release the long hold.
 */
static int
dsl_dataset_handoff_check(dsl_dataset_t *ds, void *owner, dmu_tx_t *tx)
{
	boolean_t held;

	if (!dmu_tx_is_syncing(tx))
		return (0);

	if (owner != NULL) {
		VERIFY3P(ds->ds_owner, ==, owner);
		dsl_dataset_long_rele(ds, owner);
	}

	held = dsl_dataset_long_held(ds);

	if (owner != NULL)
		dsl_dataset_long_hold(ds, owner);

	if (held)
		return (SET_ERROR(EBUSY));

	return (0);
}

int
dsl_dataset_rollback_check(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_rollback_arg_t *ddra = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	dsl_dataset_t *ds;
	int64_t unused_refres_delta;
	int error;

	error = dsl_dataset_hold(dp, ddra->ddra_fsname, FTAG, &ds);
	if (error != 0)
		return (error);

	/* must not be a snapshot */
	if (ds->ds_is_snapshot) {
		dsl_dataset_rele(ds, FTAG);
		return (SET_ERROR(EINVAL));
	}

	/* must have a most recent snapshot */
	if (dsl_dataset_phys(ds)->ds_prev_snap_txg < TXG_INITIAL) {
		dsl_dataset_rele(ds, FTAG);
		return (SET_ERROR(ESRCH));
	}

	/*
	 * No rollback to a snapshot created in the current txg, because
	 * the rollback may dirty the dataset and create blocks that are
	 * not reachable from the rootbp while having a birth txg that
	 * falls into the snapshot's range.
	 */
	if (dmu_tx_is_syncing(tx) &&
	    dsl_dataset_phys(ds)->ds_prev_snap_txg >= tx->tx_txg) {
		dsl_dataset_rele(ds, FTAG);
		return (SET_ERROR(EAGAIN));
	}

	/*
	 * If the expected target snapshot is specified, then check that
	 * the latest snapshot is it.
	 */
	if (ddra->ddra_tosnap != NULL) {
		dsl_dataset_t *snapds;

		/* Check if the target snapshot exists at all. */
		error = dsl_dataset_hold(dp, ddra->ddra_tosnap, FTAG, &snapds);
		if (error != 0) {
			/*
			 * ESRCH is used to signal that the target snapshot does
			 * not exist, while ENOENT is used to report that
			 * the rolled back dataset does not exist.
			 * ESRCH is also used to cover other cases where the
			 * target snapshot is not related to the dataset being
			 * rolled back such as being in a different pool.
			 */
			if (error == ENOENT || error == EXDEV)
				error = SET_ERROR(ESRCH);
			dsl_dataset_rele(ds, FTAG);
			return (error);
		}
		ASSERT(snapds->ds_is_snapshot);

		/* Check if the snapshot is the latest snapshot indeed. */
		if (snapds != ds->ds_prev) {
			/*
			 * Distinguish between the case where the only problem
			 * is intervening snapshots (EEXIST) vs the snapshot
			 * not being a valid target for rollback (ESRCH).
			 */
			if (snapds->ds_dir == ds->ds_dir ||
			    (dsl_dir_is_clone(ds->ds_dir) &&
			    dsl_dir_phys(ds->ds_dir)->dd_origin_obj ==
			    snapds->ds_object)) {
				error = SET_ERROR(EEXIST);
			} else {
				error = SET_ERROR(ESRCH);
			}
			dsl_dataset_rele(snapds, FTAG);
			dsl_dataset_rele(ds, FTAG);
			return (error);
		}
		dsl_dataset_rele(snapds, FTAG);
	}

	/* must not have any bookmarks after the most recent snapshot */
	nvlist_t *proprequest = fnvlist_alloc();
	fnvlist_add_boolean(proprequest, zfs_prop_to_name(ZFS_PROP_CREATETXG));
	nvlist_t *bookmarks = fnvlist_alloc();
	error = dsl_get_bookmarks_impl(ds, proprequest, bookmarks);
	fnvlist_free(proprequest);
	if (error != 0) {
		dsl_dataset_rele(ds, FTAG);
		return (error);
	}
	for (nvpair_t *pair = nvlist_next_nvpair(bookmarks, NULL);
	    pair != NULL; pair = nvlist_next_nvpair(bookmarks, pair)) {
		nvlist_t *valuenv =
		    fnvlist_lookup_nvlist(fnvpair_value_nvlist(pair),
		    zfs_prop_to_name(ZFS_PROP_CREATETXG));
		uint64_t createtxg = fnvlist_lookup_uint64(valuenv, "value");
		if (createtxg > dsl_dataset_phys(ds)->ds_prev_snap_txg) {
			fnvlist_free(bookmarks);
			dsl_dataset_rele(ds, FTAG);
			return (SET_ERROR(EEXIST));
		}
	}
	fnvlist_free(bookmarks);

	error = dsl_dataset_handoff_check(ds, ddra->ddra_owner, tx);
	if (error != 0) {
		dsl_dataset_rele(ds, FTAG);
		return (error);
	}

	/*
	 * Check if the snap we are rolling back to uses more than
	 * the refquota.
	 */
	if (ds->ds_quota != 0 &&
	    dsl_dataset_phys(ds->ds_prev)->ds_referenced_bytes > ds->ds_quota) {
		dsl_dataset_rele(ds, FTAG);
		return (SET_ERROR(EDQUOT));
	}

	/*
	 * When we do the clone swap, we will temporarily use more space
	 * due to the refreservation (the head will no longer have any
	 * unique space, so the entire amount of the refreservation will need
	 * to be free).  We will immediately destroy the clone, freeing
	 * this space, but the freeing happens over many txg's.
	 */
	unused_refres_delta = (int64_t)MIN(ds->ds_reserved,
	    dsl_dataset_phys(ds)->ds_unique_bytes);

	if (unused_refres_delta > 0 &&
	    unused_refres_delta >
	    dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE)) {
		dsl_dataset_rele(ds, FTAG);
		return (SET_ERROR(ENOSPC));
	}

	dsl_dataset_rele(ds, FTAG);
	return (0);
}

void
dsl_dataset_rollback_sync(void *arg, dmu_tx_t *tx)
{
	dsl_dataset_rollback_arg_t *ddra = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	dsl_dataset_t *ds, *clone;
	uint64_t cloneobj;
	char namebuf[ZFS_MAX_DATASET_NAME_LEN];

	VERIFY0(dsl_dataset_hold(dp, ddra->ddra_fsname, FTAG, &ds));

	dsl_dataset_name(ds->ds_prev, namebuf);
	fnvlist_add_string(ddra->ddra_result, "target", namebuf);

	cloneobj = dsl_dataset_create_sync(