1949 crash during reguid causes stale config

[unleashed.git] / usr / src / uts / common / fs / zfs / dmu_objset.c

/*
 * 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.
 */

/* Portions Copyright 2010 Robert Milkowski */

#include <sys/cred.h>
#include <sys/zfs_context.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_synctask.h>
#include <sys/dsl_deleg.h>
#include <sys/dnode.h>
#include <sys/dbuf.h>
#include <sys/zvol.h>
#include <sys/dmu_tx.h>
#include <sys/zap.h>
#include <sys/zil.h>
#include <sys/dmu_impl.h>
#include <sys/zfs_ioctl.h>
#include <sys/sa.h>
#include <sys/zfs_onexit.h>

/*
 * Needed to close a window in dnode_move() that allows the objset to be freed
 * before it can be safely accessed.
 */
krwlock_t os_lock;

void
dmu_objset_init(void)
{
        rw_init(&os_lock, NULL, RW_DEFAULT, NULL);
}

void
dmu_objset_fini(void)
{
        rw_destroy(&os_lock);
}

spa_t *
dmu_objset_spa(objset_t *os)
{
        return (os->os_spa);
}

zilog_t *
dmu_objset_zil(objset_t *os)
{
        return (os->os_zil);
}

dsl_pool_t *
dmu_objset_pool(objset_t *os)
{
        dsl_dataset_t *ds;

        if ((ds = os->os_dsl_dataset) != NULL && ds->ds_dir)
                return (ds->ds_dir->dd_pool);
        else
                return (spa_get_dsl(os->os_spa));
}

dsl_dataset_t *
dmu_objset_ds(objset_t *os)
{
        return (os->os_dsl_dataset);
}

dmu_objset_type_t
dmu_objset_type(objset_t *os)
{
        return (os->os_phys->os_type);
}

void
dmu_objset_name(objset_t *os, char *buf)
{
        dsl_dataset_name(os->os_dsl_dataset, buf);
}

uint64_t
dmu_objset_id(objset_t *os)
{
        dsl_dataset_t *ds = os->os_dsl_dataset;

        return (ds ? ds->ds_object : 0);
}

uint64_t
dmu_objset_syncprop(objset_t *os)
{
        return (os->os_sync);
}

uint64_t
dmu_objset_logbias(objset_t *os)
{
        return (os->os_logbias);
}

static void
checksum_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        /*
         * Inheritance should have been done by now.
         */
        ASSERT(newval != ZIO_CHECKSUM_INHERIT);

        os->os_checksum = zio_checksum_select(newval, ZIO_CHECKSUM_ON_VALUE);
}

static void
compression_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        /*
         * Inheritance and range checking should have been done by now.
         */
        ASSERT(newval != ZIO_COMPRESS_INHERIT);

        os->os_compress = zio_compress_select(newval, ZIO_COMPRESS_ON_VALUE);
}

static void
copies_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        /*
         * Inheritance and range checking should have been done by now.
         */
        ASSERT(newval > 0);
        ASSERT(newval <= spa_max_replication(os->os_spa));

        os->os_copies = newval;
}

static void
dedup_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;
        spa_t *spa = os->os_spa;
        enum zio_checksum checksum;

        /*
         * Inheritance should have been done by now.
         */
        ASSERT(newval != ZIO_CHECKSUM_INHERIT);

        checksum = zio_checksum_dedup_select(spa, newval, ZIO_CHECKSUM_OFF);

        os->os_dedup_checksum = checksum & ZIO_CHECKSUM_MASK;
        os->os_dedup_verify = !!(checksum & ZIO_CHECKSUM_VERIFY);
}

static void
primary_cache_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        /*
         * Inheritance and range checking should have been done by now.
         */
        ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
            newval == ZFS_CACHE_METADATA);

        os->os_primary_cache = newval;
}

static void
secondary_cache_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        /*
         * Inheritance and range checking should have been done by now.
         */
        ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
            newval == ZFS_CACHE_METADATA);

        os->os_secondary_cache = newval;
}

static void
sync_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        /*
         * Inheritance and range checking should have been done by now.
         */
        ASSERT(newval == ZFS_SYNC_STANDARD || newval == ZFS_SYNC_ALWAYS ||
            newval == ZFS_SYNC_DISABLED);

        os->os_sync = newval;
        if (os->os_zil)
                zil_set_sync(os->os_zil, newval);
}

static void
logbias_changed_cb(void *arg, uint64_t newval)
{
        objset_t *os = arg;

        ASSERT(newval == ZFS_LOGBIAS_LATENCY ||
            newval == ZFS_LOGBIAS_THROUGHPUT);
        os->os_logbias = newval;
        if (os->os_zil)
                zil_set_logbias(os->os_zil, newval);
}

void
dmu_objset_byteswap(void *buf, size_t size)
{
        objset_phys_t *osp = buf;

        ASSERT(size == OBJSET_OLD_PHYS_SIZE || 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);
        osp->os_flags = BSWAP_64(osp->os_flags);
        if (size == sizeof (objset_phys_t)) {
                dnode_byteswap(&osp->os_userused_dnode);
                dnode_byteswap(&osp->os_groupused_dnode);
        }
}

int
dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
    objset_t **osp)
{
        objset_t *os;
        int i, err;

        ASSERT(ds == NULL || MUTEX_HELD(&ds->ds_opening_lock));

        os = kmem_zalloc(sizeof (objset_t), KM_SLEEP);
        os->os_dsl_dataset = ds;
        os->os_spa = spa;
        os->os_rootbp = bp;
        if (!BP_IS_HOLE(os->os_rootbp)) {
                uint32_t aflags = ARC_WAIT;
                zbookmark_t zb;
                SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
                    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);

                if (DMU_OS_IS_L2CACHEABLE(os))
                        aflags |= ARC_L2CACHE;

                dprintf_bp(os->os_rootbp, "reading %s", "");
                /*
                 * XXX when bprewrite scrub can change the bp,
                 * and this is called from dmu_objset_open_ds_os, the bp
                 * could change, and we'll need a lock.
                 */
                err = dsl_read_nolock(NULL, spa, os->os_rootbp,
                    arc_getbuf_func, &os->os_phys_buf,
                    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &aflags, &zb);
                if (err) {
                        kmem_free(os, sizeof (objset_t));
                        /* convert checksum errors into IO errors */
                        if (err == ECKSUM)
                                err = EIO;
                        return (err);
                }

                /* Increase the blocksize if we are permitted. */
                if (spa_version(spa) >= SPA_VERSION_USERSPACE &&
                    arc_buf_size(os->os_phys_buf) < sizeof (objset_phys_t)) {
                        arc_buf_t *buf = arc_buf_alloc(spa,
                            sizeof (objset_phys_t), &os->os_phys_buf,
                            ARC_BUFC_METADATA);
                        bzero(buf->b_data, sizeof (objset_phys_t));
                        bcopy(os->os_phys_buf->b_data, buf->b_data,
                            arc_buf_size(os->os_phys_buf));
                        (void) arc_buf_remove_ref(os->os_phys_buf,
                            &os->os_phys_buf);
                        os->os_phys_buf = buf;
                }

                os->os_phys = os->os_phys_buf->b_data;
                os->os_flags = os->os_phys->os_flags;
        } else {
                int size = spa_version(spa) >= SPA_VERSION_USERSPACE ?
                    sizeof (objset_phys_t) : OBJSET_OLD_PHYS_SIZE;
                os->os_phys_buf = arc_buf_alloc(spa, size,
                    &os->os_phys_buf, ARC_BUFC_METADATA);
                os->os_phys = os->os_phys_buf->b_data;
                bzero(os->os_phys, size);
        }

        /*
         * Note: the changed_cb will be called once before the register
         * func returns, thus changing the checksum/compression from the
         * default (fletcher2/off).  Snapshots don't need to know about
         * checksum/compression/copies.
         */
        if (ds) {
                err = dsl_prop_register(ds, "primarycache",
                    primary_cache_changed_cb, os);
                if (err == 0)
                        err = dsl_prop_register(ds, "secondarycache",
                            secondary_cache_changed_cb, os);
                if (!dsl_dataset_is_snapshot(ds)) {
                        if (err == 0)
                                err = dsl_prop_register(ds, "checksum",
                                    checksum_changed_cb, os);
                        if (err == 0)
                                err = dsl_prop_register(ds, "compression",
                                    compression_changed_cb, os);
                        if (err == 0)
                                err = dsl_prop_register(ds, "copies",
                                    copies_changed_cb, os);
                        if (err == 0)
                                err = dsl_prop_register(ds, "dedup",
                                    dedup_changed_cb, os);
                        if (err == 0)
                                err = dsl_prop_register(ds, "logbias",
                                    logbias_changed_cb, os);
                        if (err == 0)
                                err = dsl_prop_register(ds, "sync",
                                    sync_changed_cb, os);
                }
                if (err) {
                        VERIFY(arc_buf_remove_ref(os->os_phys_buf,
                            &os->os_phys_buf) == 1);
                        kmem_free(os, sizeof (objset_t));
                        return (err);
                }
        } else if (ds == NULL) {
                /* It's the meta-objset. */
                os->os_checksum = ZIO_CHECKSUM_FLETCHER_4;
                os->os_compress = ZIO_COMPRESS_LZJB;
                os->os_copies = spa_max_replication(spa);
                os->os_dedup_checksum = ZIO_CHECKSUM_OFF;
                os->os_dedup_verify = 0;
                os->os_logbias = 0;
                os->os_sync = 0;
                os->os_primary_cache = ZFS_CACHE_ALL;
                os->os_secondary_cache = ZFS_CACHE_ALL;
        }

        if (ds == NULL || !dsl_dataset_is_snapshot(ds))
                os->os_zil_header = os->os_phys->os_zil_header;
        os->os_zil = zil_alloc(os, &os->os_zil_header);

        for (i = 0; i < TXG_SIZE; i++) {
                list_create(&os->os_dirty_dnodes[i], sizeof (dnode_t),
                    offsetof(dnode_t, dn_dirty_link[i]));
                list_create(&os->os_free_dnodes[i], sizeof (dnode_t),
                    offsetof(dnode_t, dn_dirty_link[i]));
        }
        list_create(&os->os_dnodes, sizeof (dnode_t),
            offsetof(dnode_t, dn_link));
        list_create(&os->os_downgraded_dbufs, sizeof (dmu_buf_impl_t),
            offsetof(dmu_buf_impl_t, db_link));

        mutex_init(&os->os_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&os->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&os->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);

        DMU_META_DNODE(os) = dnode_special_open(os,
            &os->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT,
            &os->os_meta_dnode);
        if (arc_buf_size(os->os_phys_buf) >= sizeof (objset_phys_t)) {
                DMU_USERUSED_DNODE(os) = dnode_special_open(os,
                    &os->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT,
                    &os->os_userused_dnode);
                DMU_GROUPUSED_DNODE(os) = dnode_special_open(os,
                    &os->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT,
                    &os->os_groupused_dnode);
        }

        /*
         * We should be the only thread trying to do this because we
         * have ds_opening_lock
         */
        if (ds) {
                mutex_enter(&ds->ds_lock);
                ASSERT(ds->ds_objset == NULL);
                ds->ds_objset = os;
                mutex_exit(&ds->ds_lock);
        }

        *osp = os;
        return (0);
}

int
dmu_objset_from_ds(dsl_dataset_t *ds, objset_t **osp)
{
        int err = 0;

        mutex_enter(&ds->ds_opening_lock);
        *osp = ds->ds_objset;
        if (*osp == NULL) {
                err = dmu_objset_open_impl(dsl_dataset_get_spa(ds),
                    ds, dsl_dataset_get_blkptr(ds), osp);
        }
        mutex_exit(&ds->ds_opening_lock);
        return (err);
}

/* called from zpl */
int
dmu_objset_hold(const char *name, void *tag, objset_t **osp)
{
        dsl_dataset_t *ds;
        int err;

        err = dsl_dataset_hold(name, tag, &ds);
        if (err)
                return (err);

        err = dmu_objset_from_ds(ds, osp);
        if (err)
                dsl_dataset_rele(ds, tag);

        return (err);
}

/* called from zpl */
int
dmu_objset_own(const char *name, dmu_objset_type_t type,
    boolean_t readonly, void *tag, objset_t **osp)
{
        dsl_dataset_t *ds;
        int err;

        err = dsl_dataset_own(name, B_FALSE, tag, &ds);
        if (err)
                return (err);

        err = dmu_objset_from_ds(ds, osp);
        if (err) {
                dsl_dataset_disown(ds, tag);
        } else if (type != DMU_OST_ANY && type != (*osp)->os_phys->os_type) {
                dmu_objset_disown(*osp, tag);
                return (EINVAL);
        } else if (!readonly && dsl_dataset_is_snapshot(ds)) {
                dmu_objset_disown(*osp, tag);
                return (EROFS);
        }
        return (err);
}

void
dmu_objset_rele(objset_t *os, void *tag)
{
        dsl_dataset_rele(os->os_dsl_dataset, tag);
}

void
dmu_objset_disown(objset_t *os, void *tag)
{
        dsl_dataset_disown(os->os_dsl_dataset, tag);
}

int
dmu_objset_evict_dbufs(objset_t *os)
{
        dnode_t *dn;

        mutex_enter(&os->os_lock);

        /* process the mdn last, since the other dnodes have holds on it */
        list_remove(&os->os_dnodes, DMU_META_DNODE(os));
        list_insert_tail(&os->os_dnodes, DMU_META_DNODE(os));

        /*
         * 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(&os->os_dnodes);
            dn && !dnode_add_ref(dn, FTAG);
            dn = list_next(&os->os_dnodes, dn))
                continue;

        while (dn) {
                dnode_t *next_dn = dn;

                do {
                        next_dn = list_next(&os->os_dnodes, next_dn);
                } while (next_dn && !dnode_add_ref(next_dn, FTAG));

                mutex_exit(&os->os_lock);
                dnode_evict_dbufs(dn);
                dnode_rele(dn, FTAG);
                mutex_enter(&os->os_lock);
                dn = next_dn;
        }
        dn = list_head(&os->os_dnodes);
        mutex_exit(&os->os_lock);
        return (dn != DMU_META_DNODE(os));
}

void
dmu_objset_evict(objset_t *os)
{
        dsl_dataset_t *ds = os->os_dsl_dataset;

        for (int t = 0; t < TXG_SIZE; t++)
                ASSERT(!dmu_objset_is_dirty(os, t));

        if (ds) {
                if (!dsl_dataset_is_snapshot(ds)) {
                        VERIFY(0 == dsl_prop_unregister(ds, "checksum",
                            checksum_changed_cb, os));
                        VERIFY(0 == dsl_prop_unregister(ds, "compression",
                            compression_changed_cb, os));
                        VERIFY(0 == dsl_prop_unregister(ds, "copies",
                            copies_changed_cb, os));
                        VERIFY(0 == dsl_prop_unregister(ds, "dedup",
                            dedup_changed_cb, os));
                        VERIFY(0 == dsl_prop_unregister(ds, "logbias",
                            logbias_changed_cb, os));
                        VERIFY(0 == dsl_prop_unregister(ds, "sync",
                            sync_changed_cb, os));
                }
                VERIFY(0 == dsl_prop_unregister(ds, "primarycache",
                    primary_cache_changed_cb, os));
                VERIFY(0 == dsl_prop_unregister(ds, "secondarycache",
                    secondary_cache_changed_cb, os));
        }

        if (os->os_sa)
                sa_tear_down(os);

        /*
         * We should need only a single pass over the dnode list, since
         * nothing can be added to the list at this point.
         */
        (void) dmu_objset_evict_dbufs(os);

        dnode_special_close(&os->os_meta_dnode);
        if (DMU_USERUSED_DNODE(os)) {
                dnode_special_close(&os->os_userused_dnode);
                dnode_special_close(&os->os_groupused_dnode);
        }
        zil_free(os->os_zil);

        ASSERT3P(list_head(&os->os_dnodes), ==, NULL);

        VERIFY(arc_buf_remove_ref(os->os_phys_buf, &os->os_phys_buf) == 1);

        /*
         * This is a barrier to prevent the objset from going away in
         * dnode_move() until we can safely ensure that the objset is still in
         * use. We consider the objset valid before the barrier and invalid
         * after the barrier.
         */
        rw_enter(&os_lock, RW_READER);
        rw_exit(&os_lock);

        mutex_destroy(&os->os_lock);
        mutex_destroy(&os->os_obj_lock);
        mutex_destroy(&os->os_user_ptr_lock);
        kmem_free(os, sizeof (objset_t));
}

timestruc_t
dmu_objset_snap_cmtime(objset_t *os)
{
        return (dsl_dir_snap_cmtime(os->os_dsl_dataset->ds_dir));
}

/* called from dsl for meta-objset */
objset_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_t *os;
        dnode_t *mdn;

        ASSERT(dmu_tx_is_syncing(tx));
        if (ds != NULL)
                VERIFY(0 == dmu_objset_from_ds(ds, &os));
        else
                VERIFY(0 == dmu_objset_open_impl(spa, NULL, bp, &os));

        mdn = DMU_META_DNODE(os);

        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);
        os->os_phys->os_type = type;
        if (dmu_objset_userused_enabled(os)) {
                os->os_phys->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
                os->os_flags = os->os_phys->os_flags;
        }

        dsl_dataset_dirty(ds, tx);

        return (os);
}

struct oscarg {
        void (*userfunc)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
        void *userarg;
        dsl_dataset_t *clone_origin;
        const char *lastname;
        dmu_objset_type_t type;
        uint64_t flags;
        cred_t *cr;
};

/*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_origin != NULL) {
                /* You can't clone across pools. */
                if (oa->clone_origin->ds_dir->dd_pool != dd->dd_pool)
                        return (EXDEV);

                /* You can only clone snapshots, not the head datasets. */
                if (!dsl_dataset_is_snapshot(oa->clone_origin))
                        return (EINVAL);
        }

        return (0);
}

static void
dmu_objset_create_sync(void *arg1, void *arg2, dmu_tx_t *tx)
{
        dsl_dir_t *dd = arg1;
        spa_t *spa = dd->dd_pool->dp_spa;
        struct oscarg *oa = arg2;
        uint64_t obj;

        ASSERT(dmu_tx_is_syncing(tx));

        obj = dsl_dataset_create_sync(dd, oa->lastname,
            oa->clone_origin, oa->flags, oa->cr, tx);

        if (oa->clone_origin == NULL) {
                dsl_pool_t *dp = dd->dd_pool;
                dsl_dataset_t *ds;
                blkptr_t *bp;
                objset_t *os;

                VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
                bp = dsl_dataset_get_blkptr(ds);
                ASSERT(BP_IS_HOLE(bp));

                os = dmu_objset_create_impl(spa, ds, bp, oa->type, tx);

                if (oa->userfunc)
                        oa->userfunc(os, oa->userarg, oa->cr, tx);
                dsl_dataset_rele(ds, FTAG);
        }

        spa_history_log_internal(LOG_DS_CREATE, spa, tx, "dataset = %llu", obj);
}

int
dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
    void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg)
{
        dsl_dir_t *pdd;
        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);
        }

        oa.userfunc = func;
        oa.userarg = arg;
        oa.lastname = tail;
        oa.type = type;
        oa.flags = flags;
        oa.cr = CRED();

        err = dsl_sync_task_do(pdd->dd_pool, dmu_objset_create_check,
            dmu_objset_create_sync, pdd, &oa, 5);
        dsl_dir_close(pdd, FTAG);
        return (err);
}

int
dmu_objset_clone(const char *name, dsl_dataset_t *clone_origin, uint64_t flags)
{
        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);
        }

        oa.lastname = tail;
        oa.clone_origin = clone_origin;
        oa.flags = flags;
        oa.cr = CRED();

        err = dsl_sync_task_do(pdd->dd_pool, dmu_objset_create_check,
            dmu_objset_create_sync, pdd, &oa, 5);
        dsl_dir_close(pdd, FTAG);
        return (err);
}

int
dmu_objset_destroy(const char *name, boolean_t defer)
{
        dsl_dataset_t *ds;
        int error;

        error = dsl_dataset_own(name, B_TRUE, FTAG, &ds);
        if (error == 0) {
                error = dsl_dataset_destroy(ds, FTAG, defer);
                /* dsl_dataset_destroy() closes the ds. */
        }

        return (error);
}

struct snaparg {
        dsl_sync_task_group_t *dstg;
        char *snapname;
        char *htag;
        char failed[MAXPATHLEN];
        boolean_t recursive;
        boolean_t needsuspend;
        boolean_t temporary;
        nvlist_t *props;
        struct dsl_ds_holdarg *ha;      /* only needed in the temporary case */
        dsl_dataset_t *newds;
};

static int
snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
{
        objset_t *os = arg1;
        struct snaparg *sn = arg2;
        int error;

        /* The props have already been checked by zfs_check_userprops(). */

        error = dsl_dataset_snapshot_check(os->os_dsl_dataset,
            sn->snapname, tx);
        if (error)
                return (error);

        if (sn->temporary) {
                /*
                 * Ideally we would just call
                 * dsl_dataset_user_hold_check() and
                 * dsl_dataset_destroy_check() here.  However the
                 * dataset we want to hold and destroy is the snapshot
                 * that we just confirmed we can create, but it won't
                 * exist until after these checks are run.  Do any
                 * checks we can here and if more checks are added to
                 * those routines in the future, similar checks may be
                 * necessary here.
                 */
                if (spa_version(os->os_spa) < SPA_VERSION_USERREFS)
                        return (ENOTSUP);
                /*
                 * Not checking number of tags because the tag will be
                 * unique, as it will be the only tag.
                 */
                if (strlen(sn->htag) + MAX_TAG_PREFIX_LEN >= MAXNAMELEN)
                        return (E2BIG);

                sn->ha = kmem_alloc(sizeof (struct dsl_ds_holdarg), KM_SLEEP);
                sn->ha->temphold = B_TRUE;
                sn->ha->htag = sn->htag;
        }
        return (error);
}

static void
snapshot_sync(void *arg1, void *arg2, dmu_tx_t *tx)
{
        objset_t *os = arg1;
        dsl_dataset_t *ds = os->os_dsl_dataset;
        struct snaparg *sn = arg2;

        dsl_dataset_snapshot_sync(ds, sn->snapname, tx);

        if (sn->props) {
                dsl_props_arg_t pa;
                pa.pa_props = sn->props;
                pa.pa_source = ZPROP_SRC_LOCAL;
                dsl_props_set_sync(ds->ds_prev, &pa, tx);
        }

        if (sn->temporary) {
                struct dsl_ds_destroyarg da;

                dsl_dataset_user_hold_sync(ds->ds_prev, sn->ha, tx);
                kmem_free(sn->ha, sizeof (struct dsl_ds_holdarg));
                sn->ha = NULL;
                sn->newds = ds->ds_prev;

                da.ds = ds->ds_prev;
                da.defer = B_TRUE;
                dsl_dataset_destroy_sync(&da, FTAG, tx);
        }
}

static int
dmu_objset_snapshot_one(const char *name, void *arg)
{
        struct snaparg *sn = arg;
        objset_t *os;
        int err;
        char *cp;

        /*
         * If the objset starts with a '%', then ignore it unless it was
         * explicitly named (ie, not recursive).  These hidden datasets
         * are always inconsistent, and by not opening them here, we can
         * avoid a race with dsl_dir_destroy_check().
         */
        cp = strrchr(name, '/');
        if (cp && cp[1] == '%' && sn->recursive)
                return (0);

        (void) strcpy(sn->failed, name);

        /*
         * Check permissions if we are doing a recursive snapshot.  The
         * permission checks for the starting dataset have already been
         * performed in zfs_secpolicy_snapshot()
         */
        if (sn->recursive && (err = zfs_secpolicy_snapshot_perms(name, CRED())))
                return (err);

        err = dmu_objset_hold(name, sn, &os);
        if (err != 0)
                return (err);

        /*
         * If the objset is in an inconsistent state (eg, in the process
         * of being destroyed), don't snapshot it.  As with %hidden
         * datasets, we return EBUSY if this name was explicitly
         * requested (ie, not recursive), and otherwise ignore it.
         */
        if (os->os_dsl_dataset->ds_phys->ds_flags & DS_FLAG_INCONSISTENT) {
                dmu_objset_rele(os, sn);
                return (sn->recursive ? 0 : EBUSY);
        }

        if (sn->needsuspend) {
                err = zil_suspend(dmu_objset_zil(os));
                if (err) {
                        dmu_objset_rele(os, sn);
                        return (err);
                }
        }
        dsl_sync_task_create(sn->dstg, snapshot_check, snapshot_sync,
            os, sn, 3);

        return (0);
}

int
dmu_objset_snapshot(char *fsname, char *snapname, char *tag,
    nvlist_t *props, boolean_t recursive, boolean_t temporary, int cleanup_fd)
{
        dsl_sync_task_t *dst;
        struct snaparg sn;
        spa_t *spa;
        minor_t minor;
        int err;

        (void) strcpy(sn.failed, fsname);

        err = spa_open(fsname, &spa, FTAG);
        if (err)
                return (err);

        if (temporary) {
                if (cleanup_fd < 0) {
                        spa_close(spa, FTAG);
                        return (EINVAL);
                }
                if ((err = zfs_onexit_fd_hold(cleanup_fd, &minor)) != 0) {
                        spa_close(spa, FTAG);
                        return (err);
                }
        }

        sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
        sn.snapname = snapname;
        sn.htag = tag;
        sn.props = props;
        sn.recursive = recursive;
        sn.needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
        sn.temporary = temporary;
        sn.ha = NULL;
        sn.newds = NULL;

        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 == 0)
                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;
                dsl_dataset_t *ds = os->os_dsl_dataset;
                if (dst->dst_err) {
                        dsl_dataset_name(ds, sn.failed);
                } else if (temporary) {
                        dsl_register_onexit_hold_cleanup(sn.newds, tag, minor);
                }
                if (sn.needsuspend)
                        zil_resume(dmu_objset_zil(os));
                dmu_objset_rele(os, &sn);
        }

        if (err)
                (void) strcpy(fsname, sn.failed);
        if (temporary)
                zfs_onexit_fd_rele(cleanup_fd);
        dsl_sync_task_group_destroy(sn.dstg);
        spa_close(spa, FTAG);
        return (err);
}

static void
dmu_objset_sync_dnodes(list_t *list, list_t *newlist, 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() because the
                 * meta-dnode needs to set it ouside dnode_sync().
                 */
                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);

                if (newlist) {
                        (void) dnode_add_ref(dn, newlist);
                        list_insert_tail(newlist, dn);
                }

                dnode_sync(dn, tx);
        }
}

/* ARGSUSED */
static void
dmu_objset_write_ready(zio_t *zio, arc_buf_t *abuf, void *arg)
{
        blkptr_t *bp = zio->io_bp;
        objset_t *os = arg;
        dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;

        ASSERT(bp == os->os_rootbp);
        ASSERT(BP_GET_TYPE(bp) == DMU_OT_OBJSET);
        ASSERT(BP_GET_LEVEL(bp) == 0);

        /*
         * Update rootbp fill count: it should be the number of objects
         * allocated in the object set (not counting the "special"
         * objects that are stored in the objset_phys_t -- the meta
         * dnode and user/group accounting objects).
         */
        bp->blk_fill = 0;
        for (int i = 0; i < dnp->dn_nblkptr; i++)
                bp->blk_fill += dnp->dn_blkptr[i].blk_fill;
}

/* ARGSUSED */
static void
dmu_objset_write_done(zio_t *zio, arc_buf_t *abuf, void *arg)
{
        blkptr_t *bp = zio->io_bp;
        blkptr_t *bp_orig = &zio->io_bp_orig;
        objset_t *os = arg;

        if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
                ASSERT(BP_EQUAL(bp, bp_orig));
        } else {
                dsl_dataset_t *ds = os->os_dsl_dataset;
                dmu_tx_t *tx = os->os_synctx;

                (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
                dsl_dataset_block_born(ds, bp, tx);
        }
}

/* called from dsl */
void
dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
{
        int txgoff;
        zbookmark_t zb;
        zio_prop_t zp;
        zio_t *zio;
        list_t *list;
        list_t *newlist = NULL;
        dbuf_dirty_record_t *dr;

        dprintf_ds(os->os_dsl_dataset, "txg=%llu\n", tx->tx_txg);

        ASSERT(dmu_tx_is_syncing(tx));
        /* XXX the write_done callback should really give us the tx... */
        os->os_synctx = tx;

        if (os->os_dsl_dataset == NULL) {
                /*
                 * This is the MOS.  If we have upgraded,
                 * spa_max_replication() could change, so reset
                 * os_copies here.
                 */
                os->os_copies = spa_max_replication(os->os_spa);
        }

        /*
         * Create the root block IO
         */
        SET_BOOKMARK(&zb, os->os_dsl_dataset ?
            os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
            ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
        VERIFY3U(0, ==, arc_release_bp(os->os_phys_buf, &os->os_phys_buf,
            os->os_rootbp, os->os_spa, &zb));

        dmu_write_policy(os, NULL, 0, 0, &zp);

        zio = arc_write(pio, os->os_spa, tx->tx_txg,
            os->os_rootbp, os->os_phys_buf, DMU_OS_IS_L2CACHEABLE(os), &zp,
            dmu_objset_write_ready, dmu_objset_write_done, os,
            ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);

        /*
         * Sync special dnodes - the parent IO for the sync is the root block
         */
        DMU_META_DNODE(os)->dn_zio = zio;
        dnode_sync(DMU_META_DNODE(os), tx);

        os->os_phys->os_flags = os->os_flags;

        if (DMU_USERUSED_DNODE(os) &&
            DMU_USERUSED_DNODE(os)->dn_type != DMU_OT_NONE) {
                DMU_USERUSED_DNODE(os)->dn_zio = zio;
                dnode_sync(DMU_USERUSED_DNODE(os), tx);
                DMU_GROUPUSED_DNODE(os)->dn_zio = zio;
                dnode_sync(DMU_GROUPUSED_DNODE(os), tx);
        }

        txgoff = tx->tx_txg & TXG_MASK;

        if (dmu_objset_userused_enabled(os)) {
                newlist = &os->os_synced_dnodes;
                /*
                 * We must create the list here because it uses the
                 * dn_dirty_link[] of this txg.
                 */
                list_create(newlist, sizeof (dnode_t),
                    offsetof(dnode_t, dn_dirty_link[txgoff]));
        }

        dmu_objset_sync_dnodes(&os->os_free_dnodes[txgoff], newlist, tx);
        dmu_objset_sync_dnodes(&os->os_dirty_dnodes[txgoff], newlist, tx);

        list = &DMU_META_DNODE(os)->dn_dirty_records[txgoff];
        while (dr = list_head(list)) {
                ASSERT(dr->dr_dbuf->db_level == 0);
                list_remove(list, dr);
                if (dr->dr_zio)
                        zio_nowait(dr->dr_zio);
        }
        /*
         * Free intent log blocks up to this tx.
         */
        zil_sync(os->os_zil, tx);
        os->os_phys->os_zil_header = os->os_zil_header;
        zio_nowait(zio);
}

boolean_t
dmu_objset_is_dirty(objset_t *os, uint64_t txg)
{
        return (!list_is_empty(&os->os_dirty_dnodes[txg & TXG_MASK]) ||
            !list_is_empty(&os->os_free_dnodes[txg & TXG_MASK]));
}

boolean_t
dmu_objset_is_dirty_anywhere(objset_t *os)
{
        for (int t = 0; t < TXG_SIZE; t++)
                if (dmu_objset_is_dirty(os, t))
                        return (B_TRUE);
        return (B_FALSE);
}

static objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];

void
dmu_objset_register_type(dmu_objset_type_t ost, objset_used_cb_t *cb)
{
        used_cbs[ost] = cb;
}

boolean_t
dmu_objset_userused_enabled(objset_t *os)
{
        return (spa_version(os->os_spa) >= SPA_VERSION_USERSPACE &&
            used_cbs[os->os_phys->os_type] != NULL &&
            DMU_USERUSED_DNODE(os) != NULL);
}

static void
do_userquota_update(objset_t *os, uint64_t used, uint64_t flags,
    uint64_t user, uint64_t group, boolean_t subtract, dmu_tx_t *tx)
{
        if ((flags & DNODE_FLAG_USERUSED_ACCOUNTED)) {
                int64_t delta = DNODE_SIZE + used;
                if (subtract)
                        delta = -delta;
                VERIFY3U(0, ==, zap_increment_int(os, DMU_USERUSED_OBJECT,
                    user, delta, tx));
                VERIFY3U(0, ==, zap_increment_int(os, DMU_GROUPUSED_OBJECT,
                    group, delta, tx));
        }
}

void
dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
{
        dnode_t *dn;
        list_t *list = &os->os_synced_dnodes;

        ASSERT(list_head(list) == NULL || dmu_objset_userused_enabled(os));

        while (dn = list_head(list)) {
                int flags;
                ASSERT(!DMU_OBJECT_IS_SPECIAL(dn->dn_object));
                ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE ||
                    dn->dn_phys->dn_flags &
                    DNODE_FLAG_USERUSED_ACCOUNTED);

                /* Allocate the user/groupused objects if necessary. */
                if (DMU_USERUSED_DNODE(os)->dn_type == DMU_OT_NONE) {
                        VERIFY(0 == zap_create_claim(os,
                            DMU_USERUSED_OBJECT,
                            DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
                        VERIFY(0 == zap_create_claim(os,
                            DMU_GROUPUSED_OBJECT,
                            DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
                }

                /*
                 * We intentionally modify the zap object even if the
                 * net delta is zero.  Otherwise
                 * the block of the zap obj could be shared between
                 * datasets but need to be different between them after
                 * a bprewrite.
                 */

                flags = dn->dn_id_flags;
                ASSERT(flags);
                if (flags & DN_ID_OLD_EXIST)  {
                        do_userquota_update(os, dn->dn_oldused, dn->dn_oldflags,
                            dn->dn_olduid, dn->dn_oldgid, B_TRUE, tx);
                }
                if (flags & DN_ID_NEW_EXIST) {
                        do_userquota_update(os, DN_USED_BYTES(dn->dn_phys),
                            dn->dn_phys->dn_flags,  dn->dn_newuid,
                            dn->dn_newgid, B_FALSE, tx);
                }

                mutex_enter(&dn->dn_mtx);
                dn->dn_oldused = 0;
                dn->dn_oldflags = 0;
                if (dn->dn_id_flags & DN_ID_NEW_EXIST) {
                        dn->dn_olduid = dn->dn_newuid;
                        dn->dn_oldgid = dn->dn_newgid;
                        dn->dn_id_flags |= DN_ID_OLD_EXIST;
                        if (dn->dn_bonuslen == 0)
                                dn->dn_id_flags |= DN_ID_CHKED_SPILL;
                        else
                                dn->dn_id_flags |= DN_ID_CHKED_BONUS;
                }
                dn->dn_id_flags &= ~(DN_ID_NEW_EXIST);
                mutex_exit(&dn->dn_mtx);

                list_remove(list, dn);
                dnode_rele(dn, list);
        }
}

/*
 * Returns a pointer to data to find uid/gid from
 *
 * If a dirty record for transaction group that is syncing can't
 * be found then NULL is returned.  In the NULL case it is assumed
 * the uid/gid aren't changing.
 */
static void *
dmu_objset_userquota_find_data(dmu_buf_impl_t *db, dmu_tx_t *tx)
{
        dbuf_dirty_record_t *dr, **drp;
        void *data;

        if (db->db_dirtycnt == 0)
                return (db->db.db_data);  /* Nothing is changing */

        for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
                if (dr->dr_txg == tx->tx_txg)
                        break;

        if (dr == NULL) {
                data = NULL;
        } else {
                dnode_t *dn;

                DB_DNODE_ENTER(dr->dr_dbuf);
                dn = DB_DNODE(dr->dr_dbuf);

                if (dn->dn_bonuslen == 0 &&
                    dr->dr_dbuf->db_blkid == DMU_SPILL_BLKID)
                        data = dr->dt.dl.dr_data->b_data;
                else
                        data = dr->dt.dl.dr_data;

                DB_DNODE_EXIT(dr->dr_dbuf);
        }

        return (data);
}

void
dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx)
{
        objset_t *os = dn->dn_objset;
        void *data = NULL;
        dmu_buf_impl_t *db = NULL;
        uint64_t *user, *group;
        int flags = dn->dn_id_flags;
        int error;
        boolean_t have_spill = B_FALSE;

        if (!dmu_objset_userused_enabled(dn->dn_objset))
                return;

        if (before && (flags & (DN_ID_CHKED_BONUS|DN_ID_OLD_EXIST|
            DN_ID_CHKED_SPILL)))
                return;

        if (before && dn->dn_bonuslen != 0)
                data = DN_BONUS(dn->dn_phys);
        else if (!before && dn->dn_bonuslen != 0) {
                if (dn->dn_bonus) {
                        db = dn->dn_bonus;
                        mutex_enter(&db->db_mtx);
                        data = dmu_objset_userquota_find_data(db, tx);
                } else {
                        data = DN_BONUS(dn->dn_phys);
                }
        } else if (dn->dn_bonuslen == 0 && dn->dn_bonustype == DMU_OT_SA) {
                        int rf = 0;

                        if (RW_WRITE_HELD(&dn->dn_struct_rwlock))
                                rf |= DB_RF_HAVESTRUCT;
                        error = dmu_spill_hold_by_dnode(dn,
                            rf | DB_RF_MUST_SUCCEED,
                            FTAG, (dmu_buf_t **)&db);
                        ASSERT(error == 0);
                        mutex_enter(&db->db_mtx);
                        data = (before) ? db->db.db_data :
                            dmu_objset_userquota_find_data(db, tx);
                        have_spill = B_TRUE;
        } else {
                mutex_enter(&dn->dn_mtx);
                dn->dn_id_flags |= DN_ID_CHKED_BONUS;
                mutex_exit(&dn->dn_mtx);
                return;
        }

        if (before) {
                ASSERT(data);
                user = &dn->dn_olduid;
                group = &dn->dn_oldgid;
        } else if (data) {
                user = &dn->dn_newuid;
                group = &dn->dn_newgid;
        }

        /*
         * Must always call the callback in case the object
         * type has changed and that type isn't an object type to track
         */
        error = used_cbs[os->os_phys->os_type](dn->dn_bonustype, data,
            user, group);

        /*
         * Preserve existing uid/gid when the callback can't determine
         * what the new uid/gid are and the callback returned EEXIST.
         * The EEXIST error tells us to just use the existing uid/gid.
         * If we don't know what the old values are then just assign
         * them to 0, since that is a new file  being created.
         */
        if (!before && data == NULL && error == EEXIST) {
                if (flags & DN_ID_OLD_EXIST) {
                        dn->dn_newuid = dn->dn_olduid;
                        dn->dn_newgid = dn->dn_oldgid;
                } else {
                        dn->dn_newuid = 0;
                        dn->dn_newgid = 0;
                }
                error = 0;
        }

        if (db)
                mutex_exit(&db->db_mtx);

        mutex_enter(&dn->dn_mtx);
        if (error == 0 && before)
                dn->dn_id_flags |= DN_ID_OLD_EXIST;
        if (error == 0 && !before)
                dn->dn_id_flags |= DN_ID_NEW_EXIST;

        if (have_spill) {
                dn->dn_id_flags |= DN_ID_CHKED_SPILL;
        } else {
                dn->dn_id_flags |= DN_ID_CHKED_BONUS;
        }
        mutex_exit(&dn->dn_mtx);
        if (have_spill)
                dmu_buf_rele((dmu_buf_t *)db, FTAG);
}

boolean_t
dmu_objset_userspace_present(objset_t *os)
{
        return (os->os_phys->os_flags &
            OBJSET_FLAG_USERACCOUNTING_COMPLETE);
}

int
dmu_objset_userspace_upgrade(objset_t *os)
{
        uint64_t obj;
        int err = 0;

        if (dmu_objset_userspace_present(os))
                return (0);
        if (!dmu_objset_userused_enabled(os))
                return (ENOTSUP);
        if (dmu_objset_is_snapshot(os))
                return (EINVAL);

        /*
         * We simply need to mark every object dirty, so that it will be
         * synced out and now accounted.  If this is called
         * concurrently, or if we already did some work before crashing,
         * that's fine, since we track each object's accounted state
         * independently.
         */

        for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE, 0)) {
                dmu_tx_t *tx;
                dmu_buf_t *db;
                int objerr;

                if (issig(JUSTLOOKING) && issig(FORREAL))
                        return (EINTR);

                objerr = dmu_bonus_hold(os, obj, FTAG, &db);
                if (objerr)
                        continue;
                tx = dmu_tx_create(os);
                dmu_tx_hold_bonus(tx, obj);
                objerr = dmu_tx_assign(tx, TXG_WAIT);
                if (objerr) {
                        dmu_tx_abort(tx);
                        continue;
                }
                dmu_buf_will_dirty(db, tx);
                dmu_buf_rele(db, FTAG);
                dmu_tx_commit(tx);
        }

        os->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
        txg_wait_synced(dmu_objset_pool(os), 0);
        return (0);
}

void
dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
    uint64_t *usedobjsp, uint64_t *availobjsp)
{
        dsl_dataset_space(os->os_dsl_dataset, refdbytesp, availbytesp,
            usedobjsp, availobjsp);
}

uint64_t
dmu_objset_fsid_guid(objset_t *os)
{
        return (dsl_dataset_fsid_guid(os->os_dsl_dataset));
}

void
dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat)
{
        stat->dds_type = os->os_phys->os_type;
        if (os->os_dsl_dataset)
                dsl_dataset_fast_stat(os->os_dsl_dataset, stat);
}

void
dmu_objset_stats(objset_t *os, nvlist_t *nv)
{
        ASSERT(os->os_dsl_dataset ||
            os->os_phys->os_type == DMU_OST_META);

        if (os->os_dsl_dataset != NULL)
                dsl_dataset_stats(os->os_dsl_dataset, nv);

        dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_TYPE,
            os->os_phys->os_type);
        dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERACCOUNTING,
            dmu_objset_userspace_present(os));
}

int
dmu_objset_is_snapshot(objset_t *os)
{
        if (os->os_dsl_dataset != NULL)
                return (dsl_dataset_is_snapshot(os->os_dsl_dataset));
        else
                return (B_FALSE);
}

int
dmu_snapshot_realname(objset_t *os, char *name, char *real, int maxlen,
    boolean_t *conflict)
{
        dsl_dataset_t *ds = os->os_dsl_dataset;
        uint64_t ignored;

        if (ds->ds_phys->ds_snapnames_zapobj == 0)
                return (ENOENT);

        return (zap_lookup_norm(ds->ds_dir->dd_pool->dp_meta_objset,
            ds->ds_phys->ds_snapnames_zapobj, name, 8, 1, &ignored, MT_FIRST,
            real, maxlen, conflict));
}

int
dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
    uint64_t *idp, uint64_t *offp, boolean_t *case_conflict)
{
        dsl_dataset_t *ds = os->os_dsl_dataset;
        zap_cursor_t cursor;
        zap_attribute_t attr;

        if (ds->ds_phys->ds_snapnames_zapobj == 0)
                return (ENOENT);

        zap_cursor_init_serialized(&cursor,
            ds->ds_dir->dd_pool->dp_meta_objset,
            ds->ds_phys->ds_snapnames_zapobj, *offp);

        if (zap_cursor_retrieve(&cursor, &attr) != 0) {
                zap_cursor_fini(&cursor);
                return (ENOENT);
        }

        if (strlen(attr.za_name) + 1 > namelen) {
                zap_cursor_fini(&cursor);
                return (ENAMETOOLONG);
        }

        (void) strcpy(name, attr.za_name);
        if (idp)
                *idp = attr.za_first_integer;
        if (case_conflict)
                *case_conflict = attr.za_normalization_conflict;
        zap_cursor_advance(&cursor);
        *offp = zap_cursor_serialize(&cursor);
        zap_cursor_fini(&cursor);

        return (0);
}

int
dmu_dir_list_next(objset_t *os, int namelen, char *name,
    uint64_t *idp, uint64_t *offp)
{
        dsl_dir_t *dd = os->os_dsl_dataset->ds_dir;
        zap_cursor_t cursor;
        zap_attribute_t attr;

        /* there is no next dir on a snapshot! */
        if (os->os_dsl_dataset->ds_object !=
            dd->dd_phys->dd_head_dataset_obj)
                return (ENOENT);

        zap_cursor_init_serialized(&cursor,
            dd->dd_pool->dp_meta_objset,
            dd->dd_phys->dd_child_dir_zapobj, *offp);

        if (zap_cursor_retrieve(&cursor, &attr) != 0) {
                zap_cursor_fini(&cursor);
                return (ENOENT);
        }

        if (strlen(attr.za_name) + 1 > namelen) {
                zap_cursor_fini(&cursor);
                return (ENAMETOOLONG);
        }

        (void) strcpy(name, attr.za_name);
        if (idp)
                *idp = attr.za_first_integer;
        zap_cursor_advance(&cursor);
        *offp = zap_cursor_serialize(&cursor);
        zap_cursor_fini(&cursor);

        return (0);
}

struct findarg {
        int (*func)(const char *, void *);
        void *arg;
};

/* ARGSUSED */
static int
findfunc(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
{
        struct findarg *fa = arg;
        return (fa->func(dsname, fa->arg));
}

/*
 * Find all objsets under name, and for each, call 'func(child_name, arg)'.
 * Perhaps change all callers to use dmu_objset_find_spa()?
 */
int
dmu_objset_find(char *name, int func(const char *, void *), void *arg,
    int flags)
{
        struct findarg fa;
        fa.func = func;
        fa.arg = arg;
        return (dmu_objset_find_spa(NULL, name, findfunc, &fa, flags));
}

/*
 * Find all objsets under name, call func on each
 */
int
dmu_objset_find_spa(spa_t *spa, const char *name,
    int func(spa_t *, uint64_t, const char *, void *), void *arg, int flags)
{
        dsl_dir_t *dd;
        dsl_pool_t *dp;
        dsl_dataset_t *ds;
        zap_cursor_t zc;
        zap_attribute_t *attr;
        char *child;
        uint64_t thisobj;
        int err;

        if (name == NULL)
                name = spa_name(spa);
        err = dsl_dir_open_spa(spa, name, FTAG, &dd, NULL);
        if (err)
                return (err);

        /* Don't visit hidden ($MOS & $ORIGIN) objsets. */
        if (dd->dd_myname[0] == '$') {
                dsl_dir_close(dd, FTAG);
                return (0);
        }

        thisobj = dd->dd_phys->dd_head_dataset_obj;
        attr = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
        dp = dd->dd_pool;

        /*
         * Iterate over all children.
         */
        if (flags & DS_FIND_CHILDREN) {
                for (zap_cursor_init(&zc, dp->dp_meta_objset,
                    dd->dd_phys->dd_child_dir_zapobj);
                    zap_cursor_retrieve(&zc, attr) == 0;
                    (void) zap_cursor_advance(&zc)) {
                        ASSERT(attr->za_integer_length == sizeof (uint64_t));
                        ASSERT(attr->za_num_integers == 1);

                        child = kmem_asprintf("%s/%s", name, attr->za_name);
                        err = dmu_objset_find_spa(spa, child, func, arg, flags);
                        strfree(child);
                        if (err)
                                break;
                }
                zap_cursor_fini(&zc);

                if (err) {
                        dsl_dir_close(dd, FTAG);
                        kmem_free(attr, sizeof (zap_attribute_t));
                        return (err);
                }
        }

        /*
         * Iterate over all snapshots.
         */
        if (flags & DS_FIND_SNAPSHOTS) {
                if (!dsl_pool_sync_context(dp))
                        rw_enter(&dp->dp_config_rwlock, RW_READER);
                err = dsl_dataset_hold_obj(dp, thisobj, FTAG, &ds);
                if (!dsl_pool_sync_context(dp))
                        rw_exit(&dp->dp_config_rwlock);

                if (err == 0) {
                        uint64_t snapobj = ds->ds_phys->ds_snapnames_zapobj;
                        dsl_dataset_rele(ds, FTAG);

                        for (zap_cursor_init(&zc, dp->dp_meta_objset, snapobj);
                            zap_cursor_retrieve(&zc, attr) == 0;
                            (void) zap_cursor_advance(&zc)) {
                                ASSERT(attr->za_integer_length ==
                                    sizeof (uint64_t));
                                ASSERT(attr->za_num_integers == 1);

                                child = kmem_asprintf("%s@%s",
                                    name, attr->za_name);
                                err = func(spa, attr->za_first_integer,
                                    child, arg);
                                strfree(child);
                                if (err)
                                        break;
                        }
                        zap_cursor_fini(&zc);
                }
        }

        dsl_dir_close(dd, FTAG);
        kmem_free(attr, sizeof (zap_attribute_t));

        if (err)
                return (err);

        /*
         * Apply to self if appropriate.
         */
        err = func(spa, thisobj, name, arg);
        return (err);
}

/* ARGSUSED */
int
dmu_objset_prefetch(const char *name, void *arg)
{
        dsl_dataset_t *ds;

        if (dsl_dataset_hold(name, FTAG, &ds))
                return (0);

        if (!BP_IS_HOLE(&ds->ds_phys->ds_bp)) {
                mutex_enter(&ds->ds_opening_lock);
                if (ds->ds_objset == NULL) {
                        uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
                        zbookmark_t zb;

                        SET_BOOKMARK(&zb, ds->ds_object, ZB_ROOT_OBJECT,
                            ZB_ROOT_LEVEL, ZB_ROOT_BLKID);

                        (void) dsl_read_nolock(NULL, dsl_dataset_get_spa(ds),
                            &ds->ds_phys->ds_bp, NULL, NULL,
                            ZIO_PRIORITY_ASYNC_READ,
                            ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
                            &aflags, &zb);
                }
                mutex_exit(&ds->ds_opening_lock);
        }

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

void
dmu_objset_set_user(objset_t *os, void *user_ptr)
{
        ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
        os->os_user_ptr = user_ptr;
}

void *
dmu_objset_get_user(objset_t *os)
{
        ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
        return (os->os_user_ptr);
}