void
fzap_upgrade(zap_t *zap, dmu_tx_t *tx, zap_flags_t flags)
{
	dmu_buf_t *db;
	zap_leaf_t *l;
	int i;
	zap_phys_t *zp;

	ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
	zap->zap_ismicro = FALSE;

	(void) dmu_buf_update_user(zap->zap_dbuf, zap, zap,
	    &zap->zap_f.zap_phys, zap_evict);

	mutex_init(&zap->zap_f.zap_num_entries_mtx, 0, 0, 0);
	zap->zap_f.zap_block_shift = highbit64(zap->zap_dbuf->db_size) - 1;

	zp = zap->zap_f.zap_phys;
	/*
	 * explicitly zero it since it might be coming from an
	 * initialized microzap
	 */
	bzero(zap->zap_dbuf->db_data, zap->zap_dbuf->db_size);
	zp->zap_block_type = ZBT_HEADER;
	zp->zap_magic = ZAP_MAGIC;

	zp->zap_ptrtbl.zt_shift = ZAP_EMBEDDED_PTRTBL_SHIFT(zap);

	zp->zap_freeblk = 2;		/* block 1 will be the first leaf */
	zp->zap_num_leafs = 1;
	zp->zap_num_entries = 0;
	zp->zap_salt = zap->zap_salt;
	zp->zap_normflags = zap->zap_normflags;
	zp->zap_flags = flags;

	/* block 1 will be the first leaf */
	for (i = 0; i < (1<<zp->zap_ptrtbl.zt_shift); i++)
		ZAP_EMBEDDED_PTRTBL_ENT(zap, i) = 1;

	/*
	 * set up block 1 - the first leaf
	 */
	VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
	    1<<FZAP_BLOCK_SHIFT(zap), FTAG, &db, DMU_READ_NO_PREFETCH));
	dmu_buf_will_dirty(db, tx);

	l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
	l->l_dbuf = db;
	l->l_phys = db->db_data;

	zap_leaf_init(l, zp->zap_normflags != 0);

	kmem_free(l, sizeof (zap_leaf_t));
	dmu_buf_rele(db, FTAG);
}

/*
 * Link zp into dl.  Can only fail if zp has been unlinked.
 */
int
zfs_link_create(zfs_dirlock_t *dl, znode_t *zp, dmu_tx_t *tx, int flag)
{
	znode_t *dzp = dl->dl_dzp;
	vnode_t *vp = ZTOV(zp);
	uint64_t value;
	int zp_is_dir = (vp->v_type == VDIR);
	int error;

	dmu_buf_will_dirty(zp->z_dbuf, tx);
	mutex_enter(&zp->z_lock);

	if (!(flag & ZRENAMING)) {
		if (zp->z_unlinked) {	/* no new links to unlinked zp */
			ASSERT(!(flag & (ZNEW | ZEXISTS)));
			mutex_exit(&zp->z_lock);
			return (ENOENT);
		}
		zp->z_phys->zp_links++;
	}
	zp->z_phys->zp_parent = dzp->z_id;	/* dzp is now zp's parent */

	if (!(flag & ZNEW))
		zfs_time_stamper_locked(zp, STATE_CHANGED, tx);
	mutex_exit(&zp->z_lock);

	dmu_buf_will_dirty(dzp->z_dbuf, tx);
	mutex_enter(&dzp->z_lock);
	dzp->z_phys->zp_size++;			/* one dirent added */
	dzp->z_phys->zp_links += zp_is_dir;	/* ".." link from zp */
	zfs_time_stamper_locked(dzp, CONTENT_MODIFIED, tx);
	mutex_exit(&dzp->z_lock);

	value = zfs_dirent(zp);
	error = zap_add(zp->z_zfsvfs->z_os, dzp->z_id, dl->dl_name,
	    8, 1, &value, tx);
	ASSERT(error == 0);

	dnlc_update(ZTOV(dzp), dl->dl_name, vp);

	return (0);
}

static int
zap_tryupgradedir(zap_t *zap, dmu_tx_t *tx)
{
	if (RW_WRITE_HELD(&zap->zap_rwlock))
		return (1);
	if (rw_tryupgrade(&zap->zap_rwlock)) {
		dmu_buf_will_dirty(zap->zap_dbuf, tx);
		return (1);
	}
	return (0);
}

static int
zap_table_store(zap_t *zap, zap_table_phys_t *tbl, uint64_t idx, uint64_t val,
    dmu_tx_t *tx)
{
	int err;
	uint64_t blk, off;
	int bs = FZAP_BLOCK_SHIFT(zap);
	dmu_buf_t *db;

	ASSERT(RW_LOCK_HELD(&zap->zap_rwlock));
	ASSERT(tbl->zt_blk != 0);

	dprintf("storing %llx at index %llx\n", val, idx);

	blk = idx >> (bs-3);
	off = idx & ((1<<(bs-3))-1);

	err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
	    (tbl->zt_blk + blk) << bs, FTAG, &db, DMU_READ_NO_PREFETCH);
	if (err)
		return (err);
	dmu_buf_will_dirty(db, tx);

	if (tbl->zt_nextblk != 0) {
		uint64_t idx2 = idx * 2;
		uint64_t blk2 = idx2 >> (bs-3);
		uint64_t off2 = idx2 & ((1<<(bs-3))-1);
		dmu_buf_t *db2;

		err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
		    (tbl->zt_nextblk + blk2) << bs, FTAG, &db2,
		    DMU_READ_NO_PREFETCH);
		if (err) {
			dmu_buf_rele(db, FTAG);
			return (err);
		}
		dmu_buf_will_dirty(db2, tx);
		((uint64_t *)db2->db_data)[off2] = val;
		((uint64_t *)db2->db_data)[off2+1] = val;
		dmu_buf_rele(db2, FTAG);
	}

static int
zfs_vfs_sync(struct mount *mp, __unused int waitfor, __unused vfs_context_t context)
{
	zfsvfs_t *zfsvfs = vfs_fsprivate(mp);

	ZFS_ENTER(zfsvfs);

	/*
	 * Mac OS X needs a file system modify time
	 *
	 * We use the mtime of the "com.apple.system.mtime" 
	 * extended attribute, which is associated with the
	 * file system root directory.
	 *
	 * Here we sync any mtime changes to this attribute.
	 */
	if (zfsvfs->z_mtime_vp != NULL) {
		timestruc_t  mtime;
		znode_t  *zp;
top:
		zp = VTOZ(zfsvfs->z_mtime_vp);
		ZFS_TIME_DECODE(&mtime, zp->z_phys->zp_mtime);
		if (zfsvfs->z_last_mtime_synced < mtime.tv_sec) {
			dmu_tx_t  *tx;
			int  error;

			tx = dmu_tx_create(zfsvfs->z_os);
			dmu_tx_hold_bonus(tx, zp->z_id);
			error = dmu_tx_assign(tx, zfsvfs->z_assign);
			if (error) {
				if (error == ERESTART && zfsvfs->z_assign == TXG_NOWAIT) {
					dmu_tx_wait(tx);
					dmu_tx_abort(tx);
					goto top;
				}
				dmu_tx_abort(tx);
			} else {
				dmu_buf_will_dirty(zp->z_dbuf, tx);
				dmu_tx_commit(tx);
				zfsvfs->z_last_mtime_synced = mtime.tv_sec;
			}
		}
	}

	if (zfsvfs->z_log != NULL)
		zil_commit(zfsvfs->z_log, UINT64_MAX, 0);
	else
		txg_wait_synced(dmu_objset_pool(zfsvfs->z_os), 0);
	ZFS_EXIT(zfsvfs);

	return (0);
}

int
zfs_make_xattrdir(znode_t *zp, vattr_t *vap, vnode_t **xvpp, cred_t *cr)
{
	zfsvfs_t *zfsvfs = zp->z_zfsvfs;
	znode_t *xzp;
	dmu_tx_t *tx;
	int error;
	zfs_fuid_info_t *fuidp = NULL;

	*xvpp = NULL;

	if (error = zfs_zaccess(zp, ACE_WRITE_NAMED_ATTRS, 0, B_FALSE, cr))
		return (error);

	tx = dmu_tx_create(zfsvfs->z_os);
	dmu_tx_hold_bonus(tx, zp->z_id);
	dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
	if (IS_EPHEMERAL(crgetuid(cr)) || IS_EPHEMERAL(crgetgid(cr))) {
		if (zfsvfs->z_fuid_obj == 0) {
			dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
			dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
			    FUID_SIZE_ESTIMATE(zfsvfs));
			dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, FALSE, NULL);
		} else {
			dmu_tx_hold_bonus(tx, zfsvfs->z_fuid_obj);
			dmu_tx_hold_write(tx, zfsvfs->z_fuid_obj, 0,
			    FUID_SIZE_ESTIMATE(zfsvfs));
		}
	}
	error = dmu_tx_assign(tx, zfsvfs->z_assign);
	if (error) {
		if (error == ERESTART && zfsvfs->z_assign == TXG_NOWAIT)
			dmu_tx_wait(tx);
		dmu_tx_abort(tx);
		return (error);
	}
	zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, 0, NULL, &fuidp);
	ASSERT(xzp->z_phys->zp_parent == zp->z_id);
	dmu_buf_will_dirty(zp->z_dbuf, tx);
	zp->z_phys->zp_xattr = xzp->z_id;

	(void) zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp,
	    xzp, "", NULL, fuidp, vap);
	if (fuidp)
		zfs_fuid_info_free(fuidp);
	dmu_tx_commit(tx);

	*xvpp = ZTOV(xzp);

	return (0);
}

static void
dsl_dataset_user_hold_sync_one_impl(nvlist_t *tmpholds, dsl_dataset_t *ds,
    const char *htag, minor_t minor, uint64_t now, dmu_tx_t *tx)
{
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	objset_t *mos = dp->dp_meta_objset;
	uint64_t zapobj;

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

	if (ds->ds_phys->ds_userrefs_obj == 0) {
		/*
		 * This is the first user hold for this dataset.  Create
		 * the userrefs zap object.
		 */
		dmu_buf_will_dirty(ds->ds_dbuf, tx);
		zapobj = ds->ds_phys->ds_userrefs_obj =
		    zap_create(mos, DMU_OT_USERREFS, DMU_OT_NONE, 0, tx);
	} else {
		zapobj = ds->ds_phys->ds_userrefs_obj;
	}
	ds->ds_userrefs++;

	VERIFY0(zap_add(mos, zapobj, htag, 8, 1, &now, tx));

	if (minor != 0) {
		char name[MAXNAMELEN];
		nvlist_t *tags;

		VERIFY0(dsl_pool_user_hold(dp, ds->ds_object,
		    htag, now, tx));
		(void) snprintf(name, sizeof (name), "%llx",
		    (u_longlong_t)ds->ds_object);

		if (nvlist_lookup_nvlist(tmpholds, name, &tags) != 0) {
			VERIFY0(nvlist_alloc(&tags, NV_UNIQUE_NAME,
			    KM_PUSHPAGE));
			fnvlist_add_boolean(tags, htag);
			fnvlist_add_nvlist(tmpholds, name, tags);
			fnvlist_free(tags);
		} else {
			fnvlist_add_boolean(tags, htag);
		}
	}

	spa_history_log_internal_ds(ds, "hold", tx,
	    "tag=%s temp=%d refs=%llu",
	    htag, minor != 0, ds->ds_userrefs);
}

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

void
bplist_vacate(bplist_t *bpl, dmu_tx_t *tx)
{
	mutex_enter(&bpl->bpl_lock);
	ASSERT3P(bpl->bpl_queue, ==, NULL);
	VERIFY(0 == bplist_hold(bpl));
	dmu_buf_will_dirty(bpl->bpl_dbuf, tx);
	VERIFY(0 == dmu_free_range(bpl->bpl_mos,
	    bpl->bpl_object, 0, -1ULL, tx));
	bpl->bpl_phys->bpl_entries = 0;
	bpl->bpl_phys->bpl_bytes = 0;
	if (bpl->bpl_havecomp) {
		bpl->bpl_phys->bpl_comp = 0;
		bpl->bpl_phys->bpl_uncomp = 0;
	}
	mutex_exit(&bpl->bpl_lock);
}

void
dsl_dir_sync(dsl_dir_t *dd, dmu_tx_t *tx)
{
	ASSERT(dmu_tx_is_syncing(tx));

	dmu_buf_will_dirty(dd->dd_dbuf, tx);

	mutex_enter(&dd->dd_lock);
	ASSERT3U(dd->dd_tempreserved[tx->tx_txg&TXG_MASK], ==, 0);
	dprintf_dd(dd, "txg=%llu towrite=%lluK\n", tx->tx_txg,
	    dd->dd_space_towrite[tx->tx_txg&TXG_MASK] / 1024);
	dd->dd_space_towrite[tx->tx_txg&TXG_MASK] = 0;
	mutex_exit(&dd->dd_lock);

	/* release the hold from dsl_dir_dirty */
	dmu_buf_rele(dd->dd_dbuf, dd);
}

int
zfs_make_xattrdir(znode_t *zp, vattr_t *vap, vnode_t **xvpp, cred_t *cr)
{
	zfsvfs_t *zfsvfs = zp->z_zfsvfs;
	znode_t *xzp;
	dmu_tx_t *tx;
	uint64_t xoid;
	int error;

	*xvpp = NULL;

#ifndef __APPLE__
	/* In Mac OS X access preflighting is done above the file system. */
	if (error = zfs_zaccess(zp, ACE_WRITE_NAMED_ATTRS, cr))
		return (error);
#endif /*!__APPLE__*/

	tx = dmu_tx_create(zfsvfs->z_os);
	dmu_tx_hold_bonus(tx, zp->z_id);
	dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
	error = dmu_tx_assign(tx, zfsvfs->z_assign);
	if (error) {
		if (error == ERESTART && zfsvfs->z_assign == TXG_NOWAIT)
			dmu_tx_wait(tx);
		dmu_tx_abort(tx);
		return (error);
	}
	zfs_mknode(zp, vap, &xoid, tx, cr, IS_XATTR, &xzp, 0);
	ASSERT(xzp->z_id == xoid);
	ASSERT(xzp->z_phys->zp_parent == zp->z_id);
	dmu_buf_will_dirty(zp->z_dbuf, tx);
	zp->z_phys->zp_xattr = xoid;

	(void) zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp, xzp, "");
	dmu_tx_commit(tx);
#ifdef __APPLE__
	/*
	 * Obtain and attach the vnode after committing the transaction
	 */
	zfs_attach_vnode(xzp);
#endif
	*xvpp = ZTOV(xzp);

	return (0);
}

static void
dsl_deleg_set_sync(void *arg, dmu_tx_t *tx)
{
    dsl_deleg_arg_t *dda = arg;
    dsl_dir_t *dd;
    dsl_pool_t *dp = dmu_tx_pool(tx);
    objset_t *mos = dp->dp_meta_objset;
    nvpair_t *whopair = NULL;
    uint64_t zapobj;

    VERIFY0(dsl_dir_hold(dp, dda->dda_name, FTAG, &dd, NULL));

    zapobj = dd->dd_phys->dd_deleg_zapobj;
    if (zapobj == 0) {
        dmu_buf_will_dirty(dd->dd_dbuf, tx);
        zapobj = dd->dd_phys->dd_deleg_zapobj = zap_create(mos,
                                                DMU_OT_DSL_PERMS, DMU_OT_NONE, 0, tx);
    }

    while ((whopair = nvlist_next_nvpair(dda->dda_nvlist, whopair))) {
        const char *whokey = nvpair_name(whopair);
        nvlist_t *perms;
        nvpair_t *permpair = NULL;
        uint64_t jumpobj;

        perms = fnvpair_value_nvlist(whopair);

        if (zap_lookup(mos, zapobj, whokey, 8, 1, &jumpobj) != 0) {
            jumpobj = zap_create_link(mos, DMU_OT_DSL_PERMS,
                                      zapobj, whokey, tx);
        }

        while ((permpair = nvlist_next_nvpair(perms, permpair))) {
            const char *perm = nvpair_name(permpair);
            uint64_t n = 0;

            VERIFY(zap_update(mos, jumpobj,
                              perm, 8, 1, &n, tx) == 0);
            spa_history_log_internal_dd(dd, "permission update", tx,
                                        "%s %s", whokey, perm);
        }
    }
    dsl_dir_rele(dd, FTAG);
}

static void
dsl_bookmark_destroy_sync(void *arg, dmu_tx_t *tx)
{
	dsl_bookmark_destroy_arg_t *dbda = arg;
	dsl_pool_t *dp = dmu_tx_pool(tx);
	objset_t *mos = dp->dp_meta_objset;
	nvpair_t *pair;

	for (pair = nvlist_next_nvpair(dbda->dbda_success, NULL);
	    pair != NULL; pair = nvlist_next_nvpair(dbda->dbda_success, pair)) {
		dsl_dataset_t *ds;
		char *shortname;
		uint64_t zap_cnt;

		VERIFY0(dsl_bookmark_hold_ds(dp, nvpair_name(pair),
		    &ds, FTAG, &shortname));
		VERIFY0(dsl_dataset_bookmark_remove(ds, shortname, tx));

		/*
		 * If all of this dataset's bookmarks have been destroyed,
		 * free the zap object and decrement the feature's use count.
		 */
		VERIFY0(zap_count(mos, ds->ds_bookmarks,
		    &zap_cnt));
		if (zap_cnt == 0) {
			dmu_buf_will_dirty(ds->ds_dbuf, tx);
			VERIFY0(zap_destroy(mos, ds->ds_bookmarks, tx));
			ds->ds_bookmarks = 0;
			spa_feature_decr(dp->dp_spa, SPA_FEATURE_BOOKMARKS, tx);
			VERIFY0(zap_remove(mos, ds->ds_object,
			    DS_FIELD_BOOKMARK_NAMES, tx));
		}

		spa_history_log_internal_ds(ds, "remove bookmark", tx,
		    "name=%s", shortname);

		dsl_dataset_rele(ds, FTAG);
	}
}

int
zfs_make_xattrdir(znode_t *zp, vattr_t *vap, vnode_t **xvpp, cred_t *cr)
{
	zfsvfs_t *zfsvfs = zp->z_zfsvfs;
	znode_t *xzp;
	dmu_tx_t *tx;
	uint64_t xoid;
	int error;

	*xvpp = NULL;

	if (error = zfs_zaccess(zp, ACE_WRITE_NAMED_ATTRS, cr))
		return (error);

	tx = dmu_tx_create(zfsvfs->z_os);
	dmu_tx_hold_bonus(tx, zp->z_id);
	dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
	error = dmu_tx_assign(tx, zfsvfs->z_assign);
	if (error) {
		if (error == ERESTART && zfsvfs->z_assign == TXG_NOWAIT)
			dmu_tx_wait(tx);
		dmu_tx_abort(tx);
		return (error);
	}
	zfs_mknode(zp, vap, &xoid, tx, cr, IS_XATTR, &xzp, 0);
	ASSERT(xzp->z_id == xoid);
	ASSERT(xzp->z_phys->zp_parent == zp->z_id);
	dmu_buf_will_dirty(zp->z_dbuf, tx);
	zp->z_phys->zp_xattr = xoid;

	(void) zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp, xzp, "");
	dmu_tx_commit(tx);

	*xvpp = ZTOV(xzp);

	return (0);
}

uint64_t
dsl_dir_create_sync(dsl_pool_t *dp, dsl_dir_t *pds, const char *name,
    dmu_tx_t *tx)
{
	objset_t *mos = dp->dp_meta_objset;
	uint64_t ddobj;
	dsl_dir_phys_t *ddphys;
	dmu_buf_t *dbuf;

	ddobj = dmu_object_alloc(mos, DMU_OT_DSL_DIR, 0,
	    DMU_OT_DSL_DIR, sizeof (dsl_dir_phys_t), tx);
	if (pds) {
		VERIFY(0 == zap_add(mos, pds->dd_phys->dd_child_dir_zapobj,
		    name, sizeof (uint64_t), 1, &ddobj, tx));
	} else {
		/* it's the root dir */
		VERIFY(0 == zap_add(mos, DMU_POOL_DIRECTORY_OBJECT,
		    DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1, &ddobj, tx));
	}
	VERIFY(0 == dmu_bonus_hold(mos, ddobj, FTAG, &dbuf));
	dmu_buf_will_dirty(dbuf, tx);
	ddphys = dbuf->db_data;

	ddphys->dd_creation_time = gethrestime_sec();
	if (pds)
		ddphys->dd_parent_obj = pds->dd_object;
	ddphys->dd_props_zapobj = zap_create(mos,
	    DMU_OT_DSL_PROPS, DMU_OT_NONE, 0, tx);
	ddphys->dd_child_dir_zapobj = zap_create(mos,
	    DMU_OT_DSL_DIR_CHILD_MAP, DMU_OT_NONE, 0, tx);
	if (spa_version(dp->dp_spa) >= SPA_VERSION_USED_BREAKDOWN)
		ddphys->dd_flags |= DD_FLAG_USED_BREAKDOWN;
	dmu_buf_rele(dbuf, FTAG);

	return (ddobj);
}

static int
zap_table_grow(zap_t *zap, zap_table_phys_t *tbl,
    void (*transfer_func)(const uint64_t *src, uint64_t *dst, int n),
    dmu_tx_t *tx)
{
	uint64_t b, newblk;
	dmu_buf_t *db_old, *db_new;
	int err;
	int bs = FZAP_BLOCK_SHIFT(zap);
	int hepb = 1<<(bs-4);
	/* hepb = half the number of entries in a block */

	ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
	ASSERT(tbl->zt_blk != 0);
	ASSERT(tbl->zt_numblks > 0);

	if (tbl->zt_nextblk != 0) {
		newblk = tbl->zt_nextblk;
	} else {
		newblk = zap_allocate_blocks(zap, tbl->zt_numblks * 2);
		tbl->zt_nextblk = newblk;
		ASSERT0(tbl->zt_blks_copied);
		dmu_prefetch(zap->zap_objset, zap->zap_object,
		    tbl->zt_blk << bs, tbl->zt_numblks << bs);
	}

	/*
	 * Copy the ptrtbl from the old to new location.
	 */

	b = tbl->zt_blks_copied;
	err = dmu_buf_hold(zap->zap_objset, zap->zap_object,
	    (tbl->zt_blk + b) << bs, FTAG, &db_old, DMU_READ_NO_PREFETCH);
	if (err)
		return (err);

	/* first half of entries in old[b] go to new[2*b+0] */
	VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
	    (newblk + 2*b+0) << bs, FTAG, &db_new, DMU_READ_NO_PREFETCH));
	dmu_buf_will_dirty(db_new, tx);
	transfer_func(db_old->db_data, db_new->db_data, hepb);
	dmu_buf_rele(db_new, FTAG);

	/* second half of entries in old[b] go to new[2*b+1] */
	VERIFY(0 == dmu_buf_hold(zap->zap_objset, zap->zap_object,
	    (newblk + 2*b+1) << bs, FTAG, &db_new, DMU_READ_NO_PREFETCH));
	dmu_buf_will_dirty(db_new, tx);
	transfer_func((uint64_t *)db_old->db_data + hepb,
	    db_new->db_data, hepb);
	dmu_buf_rele(db_new, FTAG);

	dmu_buf_rele(db_old, FTAG);

	tbl->zt_blks_copied++;

	dprintf("copied block %llu of %llu\n",
	    tbl->zt_blks_copied, tbl->zt_numblks);

	if (tbl->zt_blks_copied == tbl->zt_numblks) {
		(void) dmu_free_range(zap->zap_objset, zap->zap_object,
		    tbl->zt_blk << bs, tbl->zt_numblks << bs, tx);

		tbl->zt_blk = newblk;
		tbl->zt_numblks *= 2;
		tbl->zt_shift++;
		tbl->zt_nextblk = 0;
		tbl->zt_blks_copied = 0;

		dprintf("finished; numblocks now %llu (%lluk entries)\n",
		    tbl->zt_numblks, 1<<(tbl->zt_shift-10));
	}

	return (0);
}

/*ARGSUSED*/
static void
spa_history_log_sync(void *arg, dmu_tx_t *tx)
{
	nvlist_t	*nvl = arg;
	spa_t		*spa = dmu_tx_pool(tx)->dp_spa;
	objset_t	*mos = spa->spa_meta_objset;
	dmu_buf_t	*dbp;
	spa_history_phys_t *shpp;
	size_t		reclen;
	uint64_t	le_len;
	char		*record_packed = NULL;
	int		ret;

	/*
	 * If we have an older pool that doesn't have a command
	 * history object, create it now.
	 */
	mutex_enter(&spa->spa_history_lock);
	if (!spa->spa_history)
		spa_history_create_obj(spa, tx);
	mutex_exit(&spa->spa_history_lock);

	/*
	 * Get the offset of where we need to write via the bonus buffer.
	 * Update the offset when the write completes.
	 */
	VERIFY0(dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp));
	shpp = dbp->db_data;

	dmu_buf_will_dirty(dbp, tx);

#ifdef ZFS_DEBUG
	{
		dmu_object_info_t doi;
		dmu_object_info_from_db(dbp, &doi);
		ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_SPA_HISTORY_OFFSETS);
	}
#endif

	fnvlist_add_uint64(nvl, ZPOOL_HIST_TIME, gethrestime_sec());
	fnvlist_add_string(nvl, ZPOOL_HIST_HOST, utsname()->nodename);

	if (nvlist_exists(nvl, ZPOOL_HIST_CMD)) {
		zfs_dbgmsg("command: %s",
		    fnvlist_lookup_string(nvl, ZPOOL_HIST_CMD));
	} else if (nvlist_exists(nvl, ZPOOL_HIST_INT_NAME)) {
		if (nvlist_exists(nvl, ZPOOL_HIST_DSNAME)) {
			zfs_dbgmsg("txg %lld %s %s (id %llu) %s",
			    fnvlist_lookup_uint64(nvl, ZPOOL_HIST_TXG),
			    fnvlist_lookup_string(nvl, ZPOOL_HIST_INT_NAME),
			    fnvlist_lookup_string(nvl, ZPOOL_HIST_DSNAME),
			    fnvlist_lookup_uint64(nvl, ZPOOL_HIST_DSID),
			    fnvlist_lookup_string(nvl, ZPOOL_HIST_INT_STR));
		} else {
			zfs_dbgmsg("txg %lld %s %s",
			    fnvlist_lookup_uint64(nvl, ZPOOL_HIST_TXG),
			    fnvlist_lookup_string(nvl, ZPOOL_HIST_INT_NAME),
			    fnvlist_lookup_string(nvl, ZPOOL_HIST_INT_STR));
		}
		/*
		 * The history sysevent is posted only for internal history
		 * messages to show what has happened, not how it happened. For
		 * example, the following command:
		 *
		 * # zfs destroy -r tank/foo
		 *
		 * will result in one sysevent posted per dataset that is
		 * destroyed as a result of the command - which could be more
		 * than one event in total.  By contrast, if the sysevent was
		 * posted as a result of the ZPOOL_HIST_CMD key being present
		 * it would result in only one sysevent being posted with the
		 * full command line arguments, requiring the consumer to know
		 * how to parse and understand zfs(1M) command invocations.
		 */
		spa_history_log_notify(spa, nvl);
	} else if (nvlist_exists(nvl, ZPOOL_HIST_IOCTL)) {
		zfs_dbgmsg("ioctl %s",
		    fnvlist_lookup_string(nvl, ZPOOL_HIST_IOCTL));
	}

	VERIFY3U(nvlist_pack(nvl, &record_packed, &reclen, NV_ENCODE_NATIVE,
	    KM_SLEEP), ==, 0);

	mutex_enter(&spa->spa_history_lock);

	/* write out the packed length as little endian */
	le_len = LE_64((uint64_t)reclen);
	ret = spa_history_write(spa, &le_len, sizeof (le_len), shpp, tx);
	if (!ret)
		ret = spa_history_write(spa, record_packed, reclen, shpp, tx);

	/* The first command is the create, which we keep forever */
	if (ret == 0 && shpp->sh_pool_create_len == 0 &&
	    nvlist_exists(nvl, ZPOOL_HIST_CMD)) {
		shpp->sh_pool_create_len = shpp->sh_bof = shpp->sh_eof;
	}

	mutex_exit(&spa->spa_history_lock);
	fnvlist_pack_free(record_packed, reclen);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	 * replay record as complete. We deadlock trying to start a tx in
	 * a new txg to further the deletion but can't because the replay
	 * tx hasn't finished.
	 *
	 * We actually delete the object if we get a failure to create an
	 * object in zil_replay_log_record(), or after calling zil_replay().
	 */
	if (zfsvfs->z_assign >= TXG_INITIAL) {
		zfs_znode_dmu_fini(zp);
		zfs_znode_free(zp);
		return;
	}

	/*
	 * If this is an attribute directory, purge its contents.
	 */
	if (ZTOV(zp) != NULL && ZTOV(zp)->v_type == VDIR &&
	    (zp->z_phys->zp_flags & ZFS_XATTR)) {
		if (zfs_purgedir(zp) != 0) {
			/*
			 * Not enough space to delete some xattrs.
			 * Leave it in the unlinked set.
			 */
			zfs_znode_dmu_fini(zp);
			zfs_znode_free(zp);
			VFS_UNLOCK_GIANT(vfslocked);
			return;
		}
	}

	/*
	 * Free up all the data in the file.
	 */
	error = dmu_free_long_range(os, zp->z_id, 0, DMU_OBJECT_END);
	if (error) {
		/*
		 * Not enough space.  Leave the file in the unlinked set.
		 */
		zfs_znode_dmu_fini(zp);
		zfs_znode_free(zp);
		return;
	}

	/*
	 * If the file has extended attributes, we're going to unlink
	 * the xattr dir.
	 */
	if (zp->z_phys->zp_xattr) {
		error = zfs_zget(zfsvfs, zp->z_phys->zp_xattr, &xzp);
		ASSERT(error == 0);
	}

	acl_obj = zp->z_phys->zp_acl.z_acl_extern_obj;

	/*
	 * Set up the final transaction.
	 */
	tx = dmu_tx_create(os);
	dmu_tx_hold_free(tx, zp->z_id, 0, DMU_OBJECT_END);
	dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
	if (xzp) {
		dmu_tx_hold_bonus(tx, xzp->z_id);
		dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, TRUE, NULL);
	}
	if (acl_obj)
		dmu_tx_hold_free(tx, acl_obj, 0, DMU_OBJECT_END);
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error) {
		/*
		 * Not enough space to delete the file.  Leave it in the
		 * unlinked set, leaking it until the fs is remounted (at
		 * which point we'll call zfs_unlinked_drain() to process it).
		 */
		dmu_tx_abort(tx);
		zfs_znode_dmu_fini(zp);
		zfs_znode_free(zp);
		goto out;
	}

	if (xzp) {
		dmu_buf_will_dirty(xzp->z_dbuf, tx);
		mutex_enter(&xzp->z_lock);
		xzp->z_unlinked = B_TRUE;	/* mark xzp for deletion */
		xzp->z_phys->zp_links = 0;	/* no more links to it */
		mutex_exit(&xzp->z_lock);
		zfs_unlinked_add(xzp, tx);
	}

	/* Remove this znode from the unlinked set */
	VERIFY3U(0, ==,
	    zap_remove_int(zfsvfs->z_os, zfsvfs->z_unlinkedobj, zp->z_id, tx));

	zfs_znode_delete(zp, tx);

	dmu_tx_commit(tx);
out:
	if (xzp)
		VN_RELE(ZTOV(xzp));
	VFS_UNLOCK_GIANT(vfslocked);
}

/*ARGSUSED*/
static void
spa_history_log_sync(void *arg1, void *arg2, dmu_tx_t *tx)
{
	spa_t		*spa = arg1;
	history_arg_t	*hap = arg2;
	const char	*history_str = hap->ha_history_str;
	objset_t	*mos = spa->spa_meta_objset;
	dmu_buf_t	*dbp;
	spa_history_phys_t *shpp;
	size_t		reclen;
	uint64_t	le_len;
	nvlist_t	*nvrecord;
	char		*record_packed = NULL;
	int		ret;

	/*
	 * If we have an older pool that doesn't have a command
	 * history object, create it now.
	 */
	mutex_enter(&spa->spa_history_lock);
	if (!spa->spa_history)
		spa_history_create_obj(spa, tx);
	mutex_exit(&spa->spa_history_lock);

	/*
	 * Get the offset of where we need to write via the bonus buffer.
	 * Update the offset when the write completes.
	 */
	VERIFY(0 == dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp));
	shpp = dbp->db_data;

	dmu_buf_will_dirty(dbp, tx);

#ifdef ZFS_DEBUG
	{
		dmu_object_info_t doi;
		dmu_object_info_from_db(dbp, &doi);
		ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_SPA_HISTORY_OFFSETS);
	}
#endif

	VERIFY(nvlist_alloc(&nvrecord, NV_UNIQUE_NAME, KM_SLEEP) == 0);
	VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_TIME,
	    gethrestime_sec()) == 0);
	VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_WHO, hap->ha_uid) == 0);
	if (hap->ha_zone != NULL)
		VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_ZONE,
		    hap->ha_zone) == 0);
#ifdef _KERNEL
	VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_HOST,
	    utsname.nodename) == 0);
#endif
	if (hap->ha_log_type == LOG_CMD_POOL_CREATE ||
	    hap->ha_log_type == LOG_CMD_NORMAL) {
		VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_CMD,
		    history_str) == 0);

		zfs_dbgmsg("command: %s", history_str);
	} else {
		VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_INT_EVENT,
		    hap->ha_event) == 0);
		VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_TXG,
		    tx->tx_txg) == 0);
		VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_INT_STR,
		    history_str) == 0);

		zfs_dbgmsg("internal %s pool:%s txg:%llu %s",
		    zfs_history_event_names[hap->ha_event], spa_name(spa),
		    (longlong_t)tx->tx_txg, history_str);

	}

	VERIFY(nvlist_size(nvrecord, &reclen, NV_ENCODE_XDR) == 0);
	record_packed = kmem_alloc(reclen, KM_SLEEP);

	VERIFY(nvlist_pack(nvrecord, &record_packed, &reclen,
	    NV_ENCODE_XDR, KM_SLEEP) == 0);

	mutex_enter(&spa->spa_history_lock);
	if (hap->ha_log_type == LOG_CMD_POOL_CREATE)
		VERIFY(shpp->sh_eof == shpp->sh_pool_create_len);

	/* write out the packed length as little endian */
	le_len = LE_64((uint64_t)reclen);
	ret = spa_history_write(spa, &le_len, sizeof (le_len), shpp, tx);
	if (!ret)
		ret = spa_history_write(spa, record_packed, reclen, shpp, tx);

	if (!ret && hap->ha_log_type == LOG_CMD_POOL_CREATE) {
		shpp->sh_pool_create_len += sizeof (le_len) + reclen;
		shpp->sh_bof = shpp->sh_pool_create_len;
	}

	mutex_exit(&spa->spa_history_lock);
	nvlist_free(nvrecord);
	kmem_free(record_packed, reclen);
	dmu_buf_rele(dbp, FTAG);

	strfree(hap->ha_history_str);
//.........这里部分代码省略.........

void
dsl_destroy_snapshot_sync_impl(dsl_dataset_t *ds, boolean_t defer, dmu_tx_t *tx)
{
#ifdef ZFS_DEBUG
	int err;
#endif
	spa_feature_t f;
	int after_branch_point = FALSE;
	dsl_pool_t *dp = ds->ds_dir->dd_pool;
	objset_t *mos = dp->dp_meta_objset;
	dsl_dataset_t *ds_prev = NULL;
	uint64_t obj, old_unique, used = 0, comp = 0, uncomp = 0;
	dsl_dataset_t *ds_next, *ds_head, *hds;


	ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));
	ASSERT3U(dsl_dataset_phys(ds)->ds_bp.blk_birth, <=, tx->tx_txg);
	ASSERT(refcount_is_zero(&ds->ds_longholds));

	if (defer &&
	    (ds->ds_userrefs > 0 ||
	    dsl_dataset_phys(ds)->ds_num_children > 1)) {
		ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
		dmu_buf_will_dirty(ds->ds_dbuf, tx);
		dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_DEFER_DESTROY;
		spa_history_log_internal_ds(ds, "defer_destroy", tx, "");
		return;
	}

	ASSERT3U(dsl_dataset_phys(ds)->ds_num_children, <=, 1);

	/* We need to log before removing it from the namespace. */
	spa_history_log_internal_ds(ds, "destroy", tx, "");

	dsl_scan_ds_destroyed(ds, tx);

	obj = ds->ds_object;

	for (f = 0; f < SPA_FEATURES; f++) {
		if (ds->ds_feature_inuse[f]) {
			dsl_dataset_deactivate_feature(obj, f, tx);
			ds->ds_feature_inuse[f] = B_FALSE;
		}
	}
	if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
		ASSERT3P(ds->ds_prev, ==, NULL);
		VERIFY0(dsl_dataset_hold_obj(dp,
		    dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &ds_prev));
		after_branch_point =
		    (dsl_dataset_phys(ds_prev)->ds_next_snap_obj != obj);

		dmu_buf_will_dirty(ds_prev->ds_dbuf, tx);
		if (after_branch_point &&
		    dsl_dataset_phys(ds_prev)->ds_next_clones_obj != 0) {
			dsl_dataset_remove_from_next_clones(ds_prev, obj, tx);
			if (dsl_dataset_phys(ds)->ds_next_snap_obj != 0) {
				VERIFY0(zap_add_int(mos,
				    dsl_dataset_phys(ds_prev)->
				    ds_next_clones_obj,
				    dsl_dataset_phys(ds)->ds_next_snap_obj,
				    tx));
			}
		}
		if (!after_branch_point) {
			dsl_dataset_phys(ds_prev)->ds_next_snap_obj =
			    dsl_dataset_phys(ds)->ds_next_snap_obj;
		}
	}