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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 /*
     22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 #include <sys/dmu_objset.h>
     27 #include <sys/dsl_dataset.h>
     28 #include <sys/dsl_dir.h>
     29 #include <sys/dsl_prop.h>
     30 #include <sys/dsl_synctask.h>
     31 #include <sys/dmu_traverse.h>
     32 #include <sys/dmu_tx.h>
     33 #include <sys/arc.h>
     34 #include <sys/zio.h>
     35 #include <sys/zap.h>
     36 #include <sys/unique.h>
     37 #include <sys/zfs_context.h>
     38 #include <sys/zfs_ioctl.h>
     39 #include <sys/spa.h>
     40 #include <sys/zfs_znode.h>
     41 #include <sys/sunddi.h>
     42 
     43 static char *dsl_reaper = "the grim reaper";
     44 
     45 static dsl_checkfunc_t dsl_dataset_destroy_begin_check;
     46 static dsl_syncfunc_t dsl_dataset_destroy_begin_sync;
     47 static dsl_checkfunc_t dsl_dataset_rollback_check;
     48 static dsl_syncfunc_t dsl_dataset_rollback_sync;
     49 static dsl_syncfunc_t dsl_dataset_set_reservation_sync;
     50 
     51 #define	DS_REF_MAX	(1ULL << 62)
     52 
     53 #define	DSL_DEADLIST_BLOCKSIZE	SPA_MAXBLOCKSIZE
     54 
     55 #define	DSL_DATASET_IS_DESTROYED(ds)	((ds)->ds_owner == dsl_reaper)
     56 
     57 
     58 /*
     59  * Figure out how much of this delta should be propogated to the dsl_dir
     60  * layer.  If there's a refreservation, that space has already been
     61  * partially accounted for in our ancestors.
     62  */
     63 static int64_t
     64 parent_delta(dsl_dataset_t *ds, int64_t delta)
     65 {
     66 	uint64_t old_bytes, new_bytes;
     67 
     68 	if (ds->ds_reserved == 0)
     69 		return (delta);
     70 
     71 	old_bytes = MAX(ds->ds_phys->ds_unique_bytes, ds->ds_reserved);
     72 	new_bytes = MAX(ds->ds_phys->ds_unique_bytes + delta, ds->ds_reserved);
     73 
     74 	ASSERT3U(ABS((int64_t)(new_bytes - old_bytes)), <=, ABS(delta));
     75 	return (new_bytes - old_bytes);
     76 }
     77 
     78 void
     79 dsl_dataset_block_born(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
     80 {
     81 	int used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
     82 	int compressed = BP_GET_PSIZE(bp);
     83 	int uncompressed = BP_GET_UCSIZE(bp);
     84 	int64_t delta;
     85 
     86 	dprintf_bp(bp, "born, ds=%p\n", ds);
     87 
     88 	ASSERT(dmu_tx_is_syncing(tx));
     89 	/* It could have been compressed away to nothing */
     90 	if (BP_IS_HOLE(bp))
     91 		return;
     92 	ASSERT(BP_GET_TYPE(bp) != DMU_OT_NONE);
     93 	ASSERT3U(BP_GET_TYPE(bp), <, DMU_OT_NUMTYPES);
     94 	if (ds == NULL) {
     95 		/*
     96 		 * Account for the meta-objset space in its placeholder
     97 		 * dsl_dir.
     98 		 */
     99 		ASSERT3U(compressed, ==, uncompressed); /* it's all metadata */
    100 		dsl_dir_diduse_space(tx->tx_pool->dp_mos_dir, DD_USED_HEAD,
    101 		    used, compressed, uncompressed, tx);
    102 		dsl_dir_dirty(tx->tx_pool->dp_mos_dir, tx);
    103 		return;
    104 	}
    105 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
    106 	mutex_enter(&ds->ds_dir->dd_lock);
    107 	mutex_enter(&ds->ds_lock);
    108 	delta = parent_delta(ds, used);
    109 	ds->ds_phys->ds_used_bytes += used;
    110 	ds->ds_phys->ds_compressed_bytes += compressed;
    111 	ds->ds_phys->ds_uncompressed_bytes += uncompressed;
    112 	ds->ds_phys->ds_unique_bytes += used;
    113 	mutex_exit(&ds->ds_lock);
    114 	dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD, delta,
    115 	    compressed, uncompressed, tx);
    116 	dsl_dir_transfer_space(ds->ds_dir, used - delta,
    117 	    DD_USED_REFRSRV, DD_USED_HEAD, tx);
    118 	mutex_exit(&ds->ds_dir->dd_lock);
    119 }
    120 
    121 int
    122 dsl_dataset_block_kill(dsl_dataset_t *ds, blkptr_t *bp, zio_t *pio,
    123     dmu_tx_t *tx)
    124 {
    125 	int used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
    126 	int compressed = BP_GET_PSIZE(bp);
    127 	int uncompressed = BP_GET_UCSIZE(bp);
    128 
    129 	ASSERT(pio != NULL);
    130 	ASSERT(dmu_tx_is_syncing(tx));
    131 	/* No block pointer => nothing to free */
    132 	if (BP_IS_HOLE(bp))
    133 		return (0);
    134 
    135 	ASSERT(used > 0);
    136 	if (ds == NULL) {
    137 		int err;
    138 		/*
    139 		 * Account for the meta-objset space in its placeholder
    140 		 * dataset.
    141 		 */
    142 		err = dsl_free(pio, tx->tx_pool,
    143 		    tx->tx_txg, bp, NULL, NULL, ARC_NOWAIT);
    144 		ASSERT(err == 0);
    145 
    146 		dsl_dir_diduse_space(tx->tx_pool->dp_mos_dir, DD_USED_HEAD,
    147 		    -used, -compressed, -uncompressed, tx);
    148 		dsl_dir_dirty(tx->tx_pool->dp_mos_dir, tx);
    149 		return (used);
    150 	}
    151 	ASSERT3P(tx->tx_pool, ==, ds->ds_dir->dd_pool);
    152 
    153 	ASSERT(!dsl_dataset_is_snapshot(ds));
    154 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
    155 
    156 	if (bp->blk_birth > ds->ds_phys->ds_prev_snap_txg) {
    157 		int err;
    158 		int64_t delta;
    159 
    160 		dprintf_bp(bp, "freeing: %s", "");
    161 		err = dsl_free(pio, tx->tx_pool,
    162 		    tx->tx_txg, bp, NULL, NULL, ARC_NOWAIT);
    163 		ASSERT(err == 0);
    164 
    165 		mutex_enter(&ds->ds_dir->dd_lock);
    166 		mutex_enter(&ds->ds_lock);
    167 		ASSERT(ds->ds_phys->ds_unique_bytes >= used ||
    168 		    !DS_UNIQUE_IS_ACCURATE(ds));
    169 		delta = parent_delta(ds, -used);
    170 		ds->ds_phys->ds_unique_bytes -= used;
    171 		mutex_exit(&ds->ds_lock);
    172 		dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD,
    173 		    delta, -compressed, -uncompressed, tx);
    174 		dsl_dir_transfer_space(ds->ds_dir, -used - delta,
    175 		    DD_USED_REFRSRV, DD_USED_HEAD, tx);
    176 		mutex_exit(&ds->ds_dir->dd_lock);
    177 	} else {
    178 		dprintf_bp(bp, "putting on dead list: %s", "");
    179 		VERIFY(0 == bplist_enqueue(&ds->ds_deadlist, bp, tx));
    180 		ASSERT3U(ds->ds_prev->ds_object, ==,
    181 		    ds->ds_phys->ds_prev_snap_obj);
    182 		ASSERT(ds->ds_prev->ds_phys->ds_num_children > 0);
    183 		/* if (bp->blk_birth > prev prev snap txg) prev unique += bs */
    184 		if (ds->ds_prev->ds_phys->ds_next_snap_obj ==
    185 		    ds->ds_object && bp->blk_birth >
    186 		    ds->ds_prev->ds_phys->ds_prev_snap_txg) {
    187 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
    188 			mutex_enter(&ds->ds_prev->ds_lock);
    189 			ds->ds_prev->ds_phys->ds_unique_bytes += used;
    190 			mutex_exit(&ds->ds_prev->ds_lock);
    191 		}
    192 		if (bp->blk_birth > ds->ds_origin_txg) {
    193 			dsl_dir_transfer_space(ds->ds_dir, used,
    194 			    DD_USED_HEAD, DD_USED_SNAP, tx);
    195 		}
    196 	}
    197 	mutex_enter(&ds->ds_lock);
    198 	ASSERT3U(ds->ds_phys->ds_used_bytes, >=, used);
    199 	ds->ds_phys->ds_used_bytes -= used;
    200 	ASSERT3U(ds->ds_phys->ds_compressed_bytes, >=, compressed);
    201 	ds->ds_phys->ds_compressed_bytes -= compressed;
    202 	ASSERT3U(ds->ds_phys->ds_uncompressed_bytes, >=, uncompressed);
    203 	ds->ds_phys->ds_uncompressed_bytes -= uncompressed;
    204 	mutex_exit(&ds->ds_lock);
    205 
    206 	return (used);
    207 }
    208 
    209 uint64_t
    210 dsl_dataset_prev_snap_txg(dsl_dataset_t *ds)
    211 {
    212 	uint64_t trysnap = 0;
    213 
    214 	if (ds == NULL)
    215 		return (0);
    216 	/*
    217 	 * The snapshot creation could fail, but that would cause an
    218 	 * incorrect FALSE return, which would only result in an
    219 	 * overestimation of the amount of space that an operation would
    220 	 * consume, which is OK.
    221 	 *
    222 	 * There's also a small window where we could miss a pending
    223 	 * snapshot, because we could set the sync task in the quiescing
    224 	 * phase.  So this should only be used as a guess.
    225 	 */
    226 	if (ds->ds_trysnap_txg >
    227 	    spa_last_synced_txg(ds->ds_dir->dd_pool->dp_spa))
    228 		trysnap = ds->ds_trysnap_txg;
    229 	return (MAX(ds->ds_phys->ds_prev_snap_txg, trysnap));
    230 }
    231 
    232 boolean_t
    233 dsl_dataset_block_freeable(dsl_dataset_t *ds, uint64_t blk_birth)
    234 {
    235 	return (blk_birth > dsl_dataset_prev_snap_txg(ds));
    236 }
    237 
    238 /* ARGSUSED */
    239 static void
    240 dsl_dataset_evict(dmu_buf_t *db, void *dsv)
    241 {
    242 	dsl_dataset_t *ds = dsv;
    243 
    244 	ASSERT(ds->ds_owner == NULL || DSL_DATASET_IS_DESTROYED(ds));
    245 
    246 	dprintf_ds(ds, "evicting %s\n", "");
    247 
    248 	unique_remove(ds->ds_fsid_guid);
    249 
    250 	if (ds->ds_user_ptr != NULL)
    251 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
    252 
    253 	if (ds->ds_prev) {
    254 		dsl_dataset_drop_ref(ds->ds_prev, ds);
    255 		ds->ds_prev = NULL;
    256 	}
    257 
    258 	bplist_close(&ds->ds_deadlist);
    259 	if (ds->ds_dir)
    260 		dsl_dir_close(ds->ds_dir, ds);
    261 
    262 	ASSERT(!list_link_active(&ds->ds_synced_link));
    263 
    264 	mutex_destroy(&ds->ds_lock);
    265 	mutex_destroy(&ds->ds_opening_lock);
    266 	mutex_destroy(&ds->ds_deadlist.bpl_lock);
    267 	rw_destroy(&ds->ds_rwlock);
    268 	cv_destroy(&ds->ds_exclusive_cv);
    269 
    270 	kmem_free(ds, sizeof (dsl_dataset_t));
    271 }
    272 
    273 static int
    274 dsl_dataset_get_snapname(dsl_dataset_t *ds)
    275 {
    276 	dsl_dataset_phys_t *headphys;
    277 	int err;
    278 	dmu_buf_t *headdbuf;
    279 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
    280 	objset_t *mos = dp->dp_meta_objset;
    281 
    282 	if (ds->ds_snapname[0])
    283 		return (0);
    284 	if (ds->ds_phys->ds_next_snap_obj == 0)
    285 		return (0);
    286 
    287 	err = dmu_bonus_hold(mos, ds->ds_dir->dd_phys->dd_head_dataset_obj,
    288 	    FTAG, &headdbuf);
    289 	if (err)
    290 		return (err);
    291 	headphys = headdbuf->db_data;
    292 	err = zap_value_search(dp->dp_meta_objset,
    293 	    headphys->ds_snapnames_zapobj, ds->ds_object, 0, ds->ds_snapname);
    294 	dmu_buf_rele(headdbuf, FTAG);
    295 	return (err);
    296 }
    297 
    298 static int
    299 dsl_dataset_snap_lookup(dsl_dataset_t *ds, const char *name, uint64_t *value)
    300 {
    301 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
    302 	uint64_t snapobj = ds->ds_phys->ds_snapnames_zapobj;
    303 	matchtype_t mt;
    304 	int err;
    305 
    306 	if (ds->ds_phys->ds_flags & DS_FLAG_CI_DATASET)
    307 		mt = MT_FIRST;
    308 	else
    309 		mt = MT_EXACT;
    310 
    311 	err = zap_lookup_norm(mos, snapobj, name, 8, 1,
    312 	    value, mt, NULL, 0, NULL);
    313 	if (err == ENOTSUP && mt == MT_FIRST)
    314 		err = zap_lookup(mos, snapobj, name, 8, 1, value);
    315 	return (err);
    316 }
    317 
    318 static int
    319 dsl_dataset_snap_remove(dsl_dataset_t *ds, char *name, dmu_tx_t *tx)
    320 {
    321 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
    322 	uint64_t snapobj = ds->ds_phys->ds_snapnames_zapobj;
    323 	matchtype_t mt;
    324 	int err;
    325 
    326 	if (ds->ds_phys->ds_flags & DS_FLAG_CI_DATASET)
    327 		mt = MT_FIRST;
    328 	else
    329 		mt = MT_EXACT;
    330 
    331 	err = zap_remove_norm(mos, snapobj, name, mt, tx);
    332 	if (err == ENOTSUP && mt == MT_FIRST)
    333 		err = zap_remove(mos, snapobj, name, tx);
    334 	return (err);
    335 }
    336 
    337 static int
    338 dsl_dataset_get_ref(dsl_pool_t *dp, uint64_t dsobj, void *tag,
    339     dsl_dataset_t **dsp)
    340 {
    341 	objset_t *mos = dp->dp_meta_objset;
    342 	dmu_buf_t *dbuf;
    343 	dsl_dataset_t *ds;
    344 	int err;
    345 
    346 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
    347 	    dsl_pool_sync_context(dp));
    348 
    349 	err = dmu_bonus_hold(mos, dsobj, tag, &dbuf);
    350 	if (err)
    351 		return (err);
    352 	ds = dmu_buf_get_user(dbuf);
    353 	if (ds == NULL) {
    354 		dsl_dataset_t *winner;
    355 
    356 		ds = kmem_zalloc(sizeof (dsl_dataset_t), KM_SLEEP);
    357 		ds->ds_dbuf = dbuf;
    358 		ds->ds_object = dsobj;
    359 		ds->ds_phys = dbuf->db_data;
    360 
    361 		mutex_init(&ds->ds_lock, NULL, MUTEX_DEFAULT, NULL);
    362 		mutex_init(&ds->ds_opening_lock, NULL, MUTEX_DEFAULT, NULL);
    363 		mutex_init(&ds->ds_deadlist.bpl_lock, NULL, MUTEX_DEFAULT,
    364 		    NULL);
    365 		rw_init(&ds->ds_rwlock, 0, 0, 0);
    366 		cv_init(&ds->ds_exclusive_cv, NULL, CV_DEFAULT, NULL);
    367 
    368 		err = bplist_open(&ds->ds_deadlist,
    369 		    mos, ds->ds_phys->ds_deadlist_obj);
    370 		if (err == 0) {
    371 			err = dsl_dir_open_obj(dp,
    372 			    ds->ds_phys->ds_dir_obj, NULL, ds, &ds->ds_dir);
    373 		}
    374 		if (err) {
    375 			/*
    376 			 * we don't really need to close the blist if we
    377 			 * just opened it.
    378 			 */
    379 			mutex_destroy(&ds->ds_lock);
    380 			mutex_destroy(&ds->ds_opening_lock);
    381 			mutex_destroy(&ds->ds_deadlist.bpl_lock);
    382 			rw_destroy(&ds->ds_rwlock);
    383 			cv_destroy(&ds->ds_exclusive_cv);
    384 			kmem_free(ds, sizeof (dsl_dataset_t));
    385 			dmu_buf_rele(dbuf, tag);
    386 			return (err);
    387 		}
    388 
    389 		if (!dsl_dataset_is_snapshot(ds)) {
    390 			ds->ds_snapname[0] = '\0';
    391 			if (ds->ds_phys->ds_prev_snap_obj) {
    392 				err = dsl_dataset_get_ref(dp,
    393 				    ds->ds_phys->ds_prev_snap_obj,
    394 				    ds, &ds->ds_prev);
    395 			}
    396 
    397 			if (err == 0 && dsl_dir_is_clone(ds->ds_dir)) {
    398 				dsl_dataset_t *origin;
    399 
    400 				err = dsl_dataset_hold_obj(dp,
    401 				    ds->ds_dir->dd_phys->dd_origin_obj,
    402 				    FTAG, &origin);
    403 				if (err == 0) {
    404 					ds->ds_origin_txg =
    405 					    origin->ds_phys->ds_creation_txg;
    406 					dsl_dataset_rele(origin, FTAG);
    407 				}
    408 			}
    409 		} else if (zfs_flags & ZFS_DEBUG_SNAPNAMES) {
    410 			err = dsl_dataset_get_snapname(ds);
    411 		}
    412 
    413 		if (err == 0 && !dsl_dataset_is_snapshot(ds)) {
    414 			/*
    415 			 * In sync context, we're called with either no lock
    416 			 * or with the write lock.  If we're not syncing,
    417 			 * we're always called with the read lock held.
    418 			 */
    419 			boolean_t need_lock =
    420 			    !RW_WRITE_HELD(&dp->dp_config_rwlock) &&
    421 			    dsl_pool_sync_context(dp);
    422 
    423 			if (need_lock)
    424 				rw_enter(&dp->dp_config_rwlock, RW_READER);
    425 
    426 			err = dsl_prop_get_ds(ds,
    427 			    "refreservation", sizeof (uint64_t), 1,
    428 			    &ds->ds_reserved, NULL);
    429 			if (err == 0) {
    430 				err = dsl_prop_get_ds(ds,
    431 				    "refquota", sizeof (uint64_t), 1,
    432 				    &ds->ds_quota, NULL);
    433 			}
    434 
    435 			if (need_lock)
    436 				rw_exit(&dp->dp_config_rwlock);
    437 		} else {
    438 			ds->ds_reserved = ds->ds_quota = 0;
    439 		}
    440 
    441 		if (err == 0) {
    442 			winner = dmu_buf_set_user_ie(dbuf, ds, &ds->ds_phys,
    443 			    dsl_dataset_evict);
    444 		}
    445 		if (err || winner) {
    446 			bplist_close(&ds->ds_deadlist);
    447 			if (ds->ds_prev)
    448 				dsl_dataset_drop_ref(ds->ds_prev, ds);
    449 			dsl_dir_close(ds->ds_dir, ds);
    450 			mutex_destroy(&ds->ds_lock);
    451 			mutex_destroy(&ds->ds_opening_lock);
    452 			mutex_destroy(&ds->ds_deadlist.bpl_lock);
    453 			rw_destroy(&ds->ds_rwlock);
    454 			cv_destroy(&ds->ds_exclusive_cv);
    455 			kmem_free(ds, sizeof (dsl_dataset_t));
    456 			if (err) {
    457 				dmu_buf_rele(dbuf, tag);
    458 				return (err);
    459 			}
    460 			ds = winner;
    461 		} else {
    462 			ds->ds_fsid_guid =
    463 			    unique_insert(ds->ds_phys->ds_fsid_guid);
    464 		}
    465 	}
    466 	ASSERT3P(ds->ds_dbuf, ==, dbuf);
    467 	ASSERT3P(ds->ds_phys, ==, dbuf->db_data);
    468 	ASSERT(ds->ds_phys->ds_prev_snap_obj != 0 ||
    469 	    spa_version(dp->dp_spa) < SPA_VERSION_ORIGIN ||
    470 	    dp->dp_origin_snap == NULL || ds == dp->dp_origin_snap);
    471 	mutex_enter(&ds->ds_lock);
    472 	if (!dsl_pool_sync_context(dp) && DSL_DATASET_IS_DESTROYED(ds)) {
    473 		mutex_exit(&ds->ds_lock);
    474 		dmu_buf_rele(ds->ds_dbuf, tag);
    475 		return (ENOENT);
    476 	}
    477 	mutex_exit(&ds->ds_lock);
    478 	*dsp = ds;
    479 	return (0);
    480 }
    481 
    482 static int
    483 dsl_dataset_hold_ref(dsl_dataset_t *ds, void *tag)
    484 {
    485 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
    486 
    487 	/*
    488 	 * In syncing context we don't want the rwlock lock: there
    489 	 * may be an existing writer waiting for sync phase to
    490 	 * finish.  We don't need to worry about such writers, since
    491 	 * sync phase is single-threaded, so the writer can't be
    492 	 * doing anything while we are active.
    493 	 */
    494 	if (dsl_pool_sync_context(dp)) {
    495 		ASSERT(!DSL_DATASET_IS_DESTROYED(ds));
    496 		return (0);
    497 	}
    498 
    499 	/*
    500 	 * Normal users will hold the ds_rwlock as a READER until they
    501 	 * are finished (i.e., call dsl_dataset_rele()).  "Owners" will
    502 	 * drop their READER lock after they set the ds_owner field.
    503 	 *
    504 	 * If the dataset is being destroyed, the destroy thread will
    505 	 * obtain a WRITER lock for exclusive access after it's done its
    506 	 * open-context work and then change the ds_owner to
    507 	 * dsl_reaper once destruction is assured.  So threads
    508 	 * may block here temporarily, until the "destructability" of
    509 	 * the dataset is determined.
    510 	 */
    511 	ASSERT(!RW_WRITE_HELD(&dp->dp_config_rwlock));
    512 	mutex_enter(&ds->ds_lock);
    513 	while (!rw_tryenter(&ds->ds_rwlock, RW_READER)) {
    514 		rw_exit(&dp->dp_config_rwlock);
    515 		cv_wait(&ds->ds_exclusive_cv, &ds->ds_lock);
    516 		if (DSL_DATASET_IS_DESTROYED(ds)) {
    517 			mutex_exit(&ds->ds_lock);
    518 			dsl_dataset_drop_ref(ds, tag);
    519 			rw_enter(&dp->dp_config_rwlock, RW_READER);
    520 			return (ENOENT);
    521 		}
    522 		rw_enter(&dp->dp_config_rwlock, RW_READER);
    523 	}
    524 	mutex_exit(&ds->ds_lock);
    525 	return (0);
    526 }
    527 
    528 int
    529 dsl_dataset_hold_obj(dsl_pool_t *dp, uint64_t dsobj, void *tag,
    530     dsl_dataset_t **dsp)
    531 {
    532 	int err = dsl_dataset_get_ref(dp, dsobj, tag, dsp);
    533 
    534 	if (err)
    535 		return (err);
    536 	return (dsl_dataset_hold_ref(*dsp, tag));
    537 }
    538 
    539 int
    540 dsl_dataset_own_obj(dsl_pool_t *dp, uint64_t dsobj, int flags, void *owner,
    541     dsl_dataset_t **dsp)
    542 {
    543 	int err = dsl_dataset_hold_obj(dp, dsobj, owner, dsp);
    544 
    545 	ASSERT(DS_MODE_TYPE(flags) != DS_MODE_USER);
    546 
    547 	if (err)
    548 		return (err);
    549 	if (!dsl_dataset_tryown(*dsp, DS_MODE_IS_INCONSISTENT(flags), owner)) {
    550 		dsl_dataset_rele(*dsp, owner);
    551 		*dsp = NULL;
    552 		return (EBUSY);
    553 	}
    554 	return (0);
    555 }
    556 
    557 int
    558 dsl_dataset_hold(const char *name, void *tag, dsl_dataset_t **dsp)
    559 {
    560 	dsl_dir_t *dd;
    561 	dsl_pool_t *dp;
    562 	const char *snapname;
    563 	uint64_t obj;
    564 	int err = 0;
    565 
    566 	err = dsl_dir_open_spa(NULL, name, FTAG, &dd, &snapname);
    567 	if (err)
    568 		return (err);
    569 
    570 	dp = dd->dd_pool;
    571 	obj = dd->dd_phys->dd_head_dataset_obj;
    572 	rw_enter(&dp->dp_config_rwlock, RW_READER);
    573 	if (obj)
    574 		err = dsl_dataset_get_ref(dp, obj, tag, dsp);
    575 	else
    576 		err = ENOENT;
    577 	if (err)
    578 		goto out;
    579 
    580 	err = dsl_dataset_hold_ref(*dsp, tag);
    581 
    582 	/* we may be looking for a snapshot */
    583 	if (err == 0 && snapname != NULL) {
    584 		dsl_dataset_t *ds = NULL;
    585 
    586 		if (*snapname++ != '@') {
    587 			dsl_dataset_rele(*dsp, tag);
    588 			err = ENOENT;
    589 			goto out;
    590 		}
    591 
    592 		dprintf("looking for snapshot '%s'\n", snapname);
    593 		err = dsl_dataset_snap_lookup(*dsp, snapname, &obj);
    594 		if (err == 0)
    595 			err = dsl_dataset_get_ref(dp, obj, tag, &ds);
    596 		dsl_dataset_rele(*dsp, tag);
    597 
    598 		ASSERT3U((err == 0), ==, (ds != NULL));
    599 
    600 		if (ds) {
    601 			mutex_enter(&ds->ds_lock);
    602 			if (ds->ds_snapname[0] == 0)
    603 				(void) strlcpy(ds->ds_snapname, snapname,
    604 				    sizeof (ds->ds_snapname));
    605 			mutex_exit(&ds->ds_lock);
    606 			err = dsl_dataset_hold_ref(ds, tag);
    607 			*dsp = err ? NULL : ds;
    608 		}
    609 	}
    610 out:
    611 	rw_exit(&dp->dp_config_rwlock);
    612 	dsl_dir_close(dd, FTAG);
    613 	return (err);
    614 }
    615 
    616 int
    617 dsl_dataset_own(const char *name, int flags, void *owner, dsl_dataset_t **dsp)
    618 {
    619 	int err = dsl_dataset_hold(name, owner, dsp);
    620 	if (err)
    621 		return (err);
    622 	if ((*dsp)->ds_phys->ds_num_children > 0 &&
    623 	    !DS_MODE_IS_READONLY(flags)) {
    624 		dsl_dataset_rele(*dsp, owner);
    625 		return (EROFS);
    626 	}
    627 	if (!dsl_dataset_tryown(*dsp, DS_MODE_IS_INCONSISTENT(flags), owner)) {
    628 		dsl_dataset_rele(*dsp, owner);
    629 		return (EBUSY);
    630 	}
    631 	return (0);
    632 }
    633 
    634 void
    635 dsl_dataset_name(dsl_dataset_t *ds, char *name)
    636 {
    637 	if (ds == NULL) {
    638 		(void) strcpy(name, "mos");
    639 	} else {
    640 		dsl_dir_name(ds->ds_dir, name);
    641 		VERIFY(0 == dsl_dataset_get_snapname(ds));
    642 		if (ds->ds_snapname[0]) {
    643 			(void) strcat(name, "@");
    644 			/*
    645 			 * We use a "recursive" mutex so that we
    646 			 * can call dprintf_ds() with ds_lock held.
    647 			 */
    648 			if (!MUTEX_HELD(&ds->ds_lock)) {
    649 				mutex_enter(&ds->ds_lock);
    650 				(void) strcat(name, ds->ds_snapname);
    651 				mutex_exit(&ds->ds_lock);
    652 			} else {
    653 				(void) strcat(name, ds->ds_snapname);
    654 			}
    655 		}
    656 	}
    657 }
    658 
    659 static int
    660 dsl_dataset_namelen(dsl_dataset_t *ds)
    661 {
    662 	int result;
    663 
    664 	if (ds == NULL) {
    665 		result = 3;	/* "mos" */
    666 	} else {
    667 		result = dsl_dir_namelen(ds->ds_dir);
    668 		VERIFY(0 == dsl_dataset_get_snapname(ds));
    669 		if (ds->ds_snapname[0]) {
    670 			++result;	/* adding one for the @-sign */
    671 			if (!MUTEX_HELD(&ds->ds_lock)) {
    672 				mutex_enter(&ds->ds_lock);
    673 				result += strlen(ds->ds_snapname);
    674 				mutex_exit(&ds->ds_lock);
    675 			} else {
    676 				result += strlen(ds->ds_snapname);
    677 			}
    678 		}
    679 	}
    680 
    681 	return (result);
    682 }
    683 
    684 void
    685 dsl_dataset_drop_ref(dsl_dataset_t *ds, void *tag)
    686 {
    687 	dmu_buf_rele(ds->ds_dbuf, tag);
    688 }
    689 
    690 void
    691 dsl_dataset_rele(dsl_dataset_t *ds, void *tag)
    692 {
    693 	if (!dsl_pool_sync_context(ds->ds_dir->dd_pool)) {
    694 		rw_exit(&ds->ds_rwlock);
    695 	}
    696 	dsl_dataset_drop_ref(ds, tag);
    697 }
    698 
    699 void
    700 dsl_dataset_disown(dsl_dataset_t *ds, void *owner)
    701 {
    702 	ASSERT((ds->ds_owner == owner && ds->ds_dbuf) ||
    703 	    (DSL_DATASET_IS_DESTROYED(ds) && ds->ds_dbuf == NULL));
    704 
    705 	mutex_enter(&ds->ds_lock);
    706 	ds->ds_owner = NULL;
    707 	if (RW_WRITE_HELD(&ds->ds_rwlock)) {
    708 		rw_exit(&ds->ds_rwlock);
    709 		cv_broadcast(&ds->ds_exclusive_cv);
    710 	}
    711 	mutex_exit(&ds->ds_lock);
    712 	if (ds->ds_dbuf)
    713 		dsl_dataset_drop_ref(ds, owner);
    714 	else
    715 		dsl_dataset_evict(ds->ds_dbuf, ds);
    716 }
    717 
    718 boolean_t
    719 dsl_dataset_tryown(dsl_dataset_t *ds, boolean_t inconsistentok, void *owner)
    720 {
    721 	boolean_t gotit = FALSE;
    722 
    723 	mutex_enter(&ds->ds_lock);
    724 	if (ds->ds_owner == NULL &&
    725 	    (!DS_IS_INCONSISTENT(ds) || inconsistentok)) {
    726 		ds->ds_owner = owner;
    727 		if (!dsl_pool_sync_context(ds->ds_dir->dd_pool))
    728 			rw_exit(&ds->ds_rwlock);
    729 		gotit = TRUE;
    730 	}
    731 	mutex_exit(&ds->ds_lock);
    732 	return (gotit);
    733 }
    734 
    735 void
    736 dsl_dataset_make_exclusive(dsl_dataset_t *ds, void *owner)
    737 {
    738 	ASSERT3P(owner, ==, ds->ds_owner);
    739 	if (!RW_WRITE_HELD(&ds->ds_rwlock))
    740 		rw_enter(&ds->ds_rwlock, RW_WRITER);
    741 }
    742 
    743 uint64_t
    744 dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
    745     uint64_t flags, dmu_tx_t *tx)
    746 {
    747 	dsl_pool_t *dp = dd->dd_pool;
    748 	dmu_buf_t *dbuf;
    749 	dsl_dataset_phys_t *dsphys;
    750 	uint64_t dsobj;
    751 	objset_t *mos = dp->dp_meta_objset;
    752 
    753 	if (origin == NULL)
    754 		origin = dp->dp_origin_snap;
    755 
    756 	ASSERT(origin == NULL || origin->ds_dir->dd_pool == dp);
    757 	ASSERT(origin == NULL || origin->ds_phys->ds_num_children > 0);
    758 	ASSERT(dmu_tx_is_syncing(tx));
    759 	ASSERT(dd->dd_phys->dd_head_dataset_obj == 0);
    760 
    761 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
    762 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
    763 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
    764 	dmu_buf_will_dirty(dbuf, tx);
    765 	dsphys = dbuf->db_data;
    766 	bzero(dsphys, sizeof (dsl_dataset_phys_t));
    767 	dsphys->ds_dir_obj = dd->dd_object;
    768 	dsphys->ds_flags = flags;
    769 	dsphys->ds_fsid_guid = unique_create();
    770 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
    771 	    sizeof (dsphys->ds_guid));
    772 	dsphys->ds_snapnames_zapobj =
    773 	    zap_create_norm(mos, U8_TEXTPREP_TOUPPER, DMU_OT_DSL_DS_SNAP_MAP,
    774 	    DMU_OT_NONE, 0, tx);
    775 	dsphys->ds_creation_time = gethrestime_sec();
    776 	dsphys->ds_creation_txg = tx->tx_txg == TXG_INITIAL ? 1 : tx->tx_txg;
    777 	dsphys->ds_deadlist_obj =
    778 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
    779 
    780 	if (origin) {
    781 		dsphys->ds_prev_snap_obj = origin->ds_object;
    782 		dsphys->ds_prev_snap_txg =
    783 		    origin->ds_phys->ds_creation_txg;
    784 		dsphys->ds_used_bytes =
    785 		    origin->ds_phys->ds_used_bytes;
    786 		dsphys->ds_compressed_bytes =
    787 		    origin->ds_phys->ds_compressed_bytes;
    788 		dsphys->ds_uncompressed_bytes =
    789 		    origin->ds_phys->ds_uncompressed_bytes;
    790 		dsphys->ds_bp = origin->ds_phys->ds_bp;
    791 		dsphys->ds_flags |= origin->ds_phys->ds_flags;
    792 
    793 		dmu_buf_will_dirty(origin->ds_dbuf, tx);
    794 		origin->ds_phys->ds_num_children++;
    795 
    796 		if (spa_version(dp->dp_spa) >= SPA_VERSION_NEXT_CLONES) {
    797 			if (origin->ds_phys->ds_next_clones_obj == 0) {
    798 				origin->ds_phys->ds_next_clones_obj =
    799 				    zap_create(mos,
    800 				    DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
    801 			}
    802 			VERIFY(0 == zap_add_int(mos,
    803 			    origin->ds_phys->ds_next_clones_obj,
    804 			    dsobj, tx));
    805 		}
    806 
    807 		dmu_buf_will_dirty(dd->dd_dbuf, tx);
    808 		dd->dd_phys->dd_origin_obj = origin->ds_object;
    809 	}
    810 
    811 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
    812 		dsphys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
    813 
    814 	dmu_buf_rele(dbuf, FTAG);
    815 
    816 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
    817 	dd->dd_phys->dd_head_dataset_obj = dsobj;
    818 
    819 	return (dsobj);
    820 }
    821 
    822 uint64_t
    823 dsl_dataset_create_sync(dsl_dir_t *pdd, const char *lastname,
    824     dsl_dataset_t *origin, uint64_t flags, cred_t *cr, dmu_tx_t *tx)
    825 {
    826 	dsl_pool_t *dp = pdd->dd_pool;
    827 	uint64_t dsobj, ddobj;
    828 	dsl_dir_t *dd;
    829 
    830 	ASSERT(lastname[0] != '@');
    831 
    832 	ddobj = dsl_dir_create_sync(dp, pdd, lastname, tx);
    833 	VERIFY(0 == dsl_dir_open_obj(dp, ddobj, lastname, FTAG, &dd));
    834 
    835 	dsobj = dsl_dataset_create_sync_dd(dd, origin, flags, tx);
    836 
    837 	dsl_deleg_set_create_perms(dd, tx, cr);
    838 
    839 	dsl_dir_close(dd, FTAG);
    840 
    841 	return (dsobj);
    842 }
    843 
    844 struct destroyarg {
    845 	dsl_sync_task_group_t *dstg;
    846 	char *snapname;
    847 	char *failed;
    848 };
    849 
    850 static int
    851 dsl_snapshot_destroy_one(char *name, void *arg)
    852 {
    853 	struct destroyarg *da = arg;
    854 	dsl_dataset_t *ds;
    855 	char *cp;
    856 	int err;
    857 
    858 	(void) strcat(name, "@");
    859 	(void) strcat(name, da->snapname);
    860 	err = dsl_dataset_own(name, DS_MODE_READONLY | DS_MODE_INCONSISTENT,
    861 	    da->dstg, &ds);
    862 	cp = strchr(name, '@');
    863 	*cp = '\0';
    864 	if (err == 0) {
    865 		dsl_dataset_make_exclusive(ds, da->dstg);
    866 		if (ds->ds_user_ptr) {
    867 			ds->ds_user_evict_func(ds, ds->ds_user_ptr);
    868 			ds->ds_user_ptr = NULL;
    869 		}
    870 		dsl_sync_task_create(da->dstg, dsl_dataset_destroy_check,
    871 		    dsl_dataset_destroy_sync, ds, da->dstg, 0);
    872 	} else if (err == ENOENT) {
    873 		err = 0;
    874 	} else {
    875 		(void) strcpy(da->failed, name);
    876 	}
    877 	return (err);
    878 }
    879 
    880 /*
    881  * Destroy 'snapname' in all descendants of 'fsname'.
    882  */
    883 #pragma weak dmu_snapshots_destroy = dsl_snapshots_destroy
    884 int
    885 dsl_snapshots_destroy(char *fsname, char *snapname)
    886 {
    887 	int err;
    888 	struct destroyarg da;
    889 	dsl_sync_task_t *dst;
    890 	spa_t *spa;
    891 
    892 	err = spa_open(fsname, &spa, FTAG);
    893 	if (err)
    894 		return (err);
    895 	da.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
    896 	da.snapname = snapname;
    897 	da.failed = fsname;
    898 
    899 	err = dmu_objset_find(fsname,
    900 	    dsl_snapshot_destroy_one, &da, DS_FIND_CHILDREN);
    901 
    902 	if (err == 0)
    903 		err = dsl_sync_task_group_wait(da.dstg);
    904 
    905 	for (dst = list_head(&da.dstg->dstg_tasks); dst;
    906 	    dst = list_next(&da.dstg->dstg_tasks, dst)) {
    907 		dsl_dataset_t *ds = dst->dst_arg1;
    908 		/*
    909 		 * Return the file system name that triggered the error
    910 		 */
    911 		if (dst->dst_err) {
    912 			dsl_dataset_name(ds, fsname);
    913 			*strchr(fsname, '@') = '\0';
    914 		}
    915 		dsl_dataset_disown(ds, da.dstg);
    916 	}
    917 
    918 	dsl_sync_task_group_destroy(da.dstg);
    919 	spa_close(spa, FTAG);
    920 	return (err);
    921 }
    922 
    923 /*
    924  * ds must be opened as OWNER.  On return (whether successful or not),
    925  * ds will be closed and caller can no longer dereference it.
    926  */
    927 int
    928 dsl_dataset_destroy(dsl_dataset_t *ds, void *tag)
    929 {
    930 	int err;
    931 	dsl_sync_task_group_t *dstg;
    932 	objset_t *os;
    933 	dsl_dir_t *dd;
    934 	uint64_t obj;
    935 
    936 	if (dsl_dataset_is_snapshot(ds)) {
    937 		/* Destroying a snapshot is simpler */
    938 		dsl_dataset_make_exclusive(ds, tag);
    939 
    940 		if (ds->ds_user_ptr) {
    941 			ds->ds_user_evict_func(ds, ds->ds_user_ptr);
    942 			ds->ds_user_ptr = NULL;
    943 		}
    944 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
    945 		    dsl_dataset_destroy_check, dsl_dataset_destroy_sync,
    946 		    ds, tag, 0);
    947 		goto out;
    948 	}
    949 
    950 	dd = ds->ds_dir;
    951 
    952 	/*
    953 	 * Check for errors and mark this ds as inconsistent, in
    954 	 * case we crash while freeing the objects.
    955 	 */
    956 	err = dsl_sync_task_do(dd->dd_pool, dsl_dataset_destroy_begin_check,
    957 	    dsl_dataset_destroy_begin_sync, ds, NULL, 0);
    958 	if (err)
    959 		goto out;
    960 
    961 	err = dmu_objset_open_ds(ds, DMU_OST_ANY, &os);
    962 	if (err)
    963 		goto out;
    964 
    965 	/*
    966 	 * remove the objects in open context, so that we won't
    967 	 * have too much to do in syncing context.
    968 	 */
    969 	for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE,
    970 	    ds->ds_phys->ds_prev_snap_txg)) {
    971 		/*
    972 		 * Ignore errors, if there is not enough disk space
    973 		 * we will deal with it in dsl_dataset_destroy_sync().
    974 		 */
    975 		(void) dmu_free_object(os, obj);
    976 	}
    977 
    978 	/*
    979 	 * We need to sync out all in-flight IO before we try to evict
    980 	 * (the dataset evict func is trying to clear the cached entries
    981 	 * for this dataset in the ARC).
    982 	 */
    983 	txg_wait_synced(dd->dd_pool, 0);
    984 
    985 	/*
    986 	 * If we managed to free all the objects in open
    987 	 * context, the user space accounting should be zero.
    988 	 */
    989 	if (ds->ds_phys->ds_bp.blk_fill == 0 &&
    990 	    dmu_objset_userused_enabled(os->os)) {
    991 		uint64_t count;
    992 
    993 		ASSERT(zap_count(os, DMU_USERUSED_OBJECT, &count) != 0 ||
    994 		    count == 0);
    995 		ASSERT(zap_count(os, DMU_GROUPUSED_OBJECT, &count) != 0 ||
    996 		    count == 0);
    997 	}
    998 
    999 	dmu_objset_close(os);
   1000 	if (err != ESRCH)
   1001 		goto out;
   1002 
   1003 	rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
   1004 	err = dsl_dir_open_obj(dd->dd_pool, dd->dd_object, NULL, FTAG, &dd);
   1005 	rw_exit(&dd->dd_pool->dp_config_rwlock);
   1006 
   1007 	if (err)
   1008 		goto out;
   1009 
   1010 	if (ds->ds_user_ptr) {
   1011 		/*
   1012 		 * We need to sync out all in-flight IO before we try
   1013 		 * to evict (the dataset evict func is trying to clear
   1014 		 * the cached entries for this dataset in the ARC).
   1015 		 */
   1016 		txg_wait_synced(dd->dd_pool, 0);
   1017 	}
   1018 
   1019 	/*
   1020 	 * Blow away the dsl_dir + head dataset.
   1021 	 */
   1022 	dsl_dataset_make_exclusive(ds, tag);
   1023 	if (ds->ds_user_ptr) {
   1024 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
   1025 		ds->ds_user_ptr = NULL;
   1026 	}
   1027 	dstg = dsl_sync_task_group_create(ds->ds_dir->dd_pool);
   1028 	dsl_sync_task_create(dstg, dsl_dataset_destroy_check,
   1029 	    dsl_dataset_destroy_sync, ds, tag, 0);
   1030 	dsl_sync_task_create(dstg, dsl_dir_destroy_check,
   1031 	    dsl_dir_destroy_sync, dd, FTAG, 0);
   1032 	err = dsl_sync_task_group_wait(dstg);
   1033 	dsl_sync_task_group_destroy(dstg);
   1034 	/* if it is successful, dsl_dir_destroy_sync will close the dd */
   1035 	if (err)
   1036 		dsl_dir_close(dd, FTAG);
   1037 out:
   1038 	dsl_dataset_disown(ds, tag);
   1039 	return (err);
   1040 }
   1041 
   1042 int
   1043 dsl_dataset_rollback(dsl_dataset_t *ds, dmu_objset_type_t ost)
   1044 {
   1045 	int err;
   1046 
   1047 	ASSERT(ds->ds_owner);
   1048 
   1049 	dsl_dataset_make_exclusive(ds, ds->ds_owner);
   1050 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
   1051 	    dsl_dataset_rollback_check, dsl_dataset_rollback_sync,
   1052 	    ds, &ost, 0);
   1053 	/* drop exclusive access */
   1054 	mutex_enter(&ds->ds_lock);
   1055 	rw_exit(&ds->ds_rwlock);
   1056 	cv_broadcast(&ds->ds_exclusive_cv);
   1057 	mutex_exit(&ds->ds_lock);
   1058 	return (err);
   1059 }
   1060 
   1061 void *
   1062 dsl_dataset_set_user_ptr(dsl_dataset_t *ds,
   1063     void *p, dsl_dataset_evict_func_t func)
   1064 {
   1065 	void *old;
   1066 
   1067 	mutex_enter(&ds->ds_lock);
   1068 	old = ds->ds_user_ptr;
   1069 	if (old == NULL) {
   1070 		ds->ds_user_ptr = p;
   1071 		ds->ds_user_evict_func = func;
   1072 	}
   1073 	mutex_exit(&ds->ds_lock);
   1074 	return (old);
   1075 }
   1076 
   1077 void *
   1078 dsl_dataset_get_user_ptr(dsl_dataset_t *ds)
   1079 {
   1080 	return (ds->ds_user_ptr);
   1081 }
   1082 
   1083 blkptr_t *
   1084 dsl_dataset_get_blkptr(dsl_dataset_t *ds)
   1085 {
   1086 	return (&ds->ds_phys->ds_bp);
   1087 }
   1088 
   1089 void
   1090 dsl_dataset_set_blkptr(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
   1091 {
   1092 	ASSERT(dmu_tx_is_syncing(tx));
   1093 	/* If it's the meta-objset, set dp_meta_rootbp */
   1094 	if (ds == NULL) {
   1095 		tx->tx_pool->dp_meta_rootbp = *bp;
   1096 	} else {
   1097 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
   1098 		ds->ds_phys->ds_bp = *bp;
   1099 	}
   1100 }
   1101 
   1102 spa_t *
   1103 dsl_dataset_get_spa(dsl_dataset_t *ds)
   1104 {
   1105 	return (ds->ds_dir->dd_pool->dp_spa);
   1106 }
   1107 
   1108 void
   1109 dsl_dataset_dirty(dsl_dataset_t *ds, dmu_tx_t *tx)
   1110 {
   1111 	dsl_pool_t *dp;
   1112 
   1113 	if (ds == NULL) /* this is the meta-objset */
   1114 		return;
   1115 
   1116 	ASSERT(ds->ds_user_ptr != NULL);
   1117 
   1118 	if (ds->ds_phys->ds_next_snap_obj != 0)
   1119 		panic("dirtying snapshot!");
   1120 
   1121 	dp = ds->ds_dir->dd_pool;
   1122 
   1123 	if (txg_list_add(&dp->dp_dirty_datasets, ds, tx->tx_txg) == 0) {
   1124 		/* up the hold count until we can be written out */
   1125 		dmu_buf_add_ref(ds->ds_dbuf, ds);
   1126 	}
   1127 }
   1128 
   1129 /*
   1130  * The unique space in the head dataset can be calculated by subtracting
   1131  * the space used in the most recent snapshot, that is still being used
   1132  * in this file system, from the space currently in use.  To figure out
   1133  * the space in the most recent snapshot still in use, we need to take
   1134  * the total space used in the snapshot and subtract out the space that
   1135  * has been freed up since the snapshot was taken.
   1136  */
   1137 static void
   1138 dsl_dataset_recalc_head_uniq(dsl_dataset_t *ds)
   1139 {
   1140 	uint64_t mrs_used;
   1141 	uint64_t dlused, dlcomp, dluncomp;
   1142 
   1143 	ASSERT(ds->ds_object == ds->ds_dir->dd_phys->dd_head_dataset_obj);
   1144 
   1145 	if (ds->ds_phys->ds_prev_snap_obj != 0)
   1146 		mrs_used = ds->ds_prev->ds_phys->ds_used_bytes;
   1147 	else
   1148 		mrs_used = 0;
   1149 
   1150 	VERIFY(0 == bplist_space(&ds->ds_deadlist, &dlused, &dlcomp,
   1151 	    &dluncomp));
   1152 
   1153 	ASSERT3U(dlused, <=, mrs_used);
   1154 	ds->ds_phys->ds_unique_bytes =
   1155 	    ds->ds_phys->ds_used_bytes - (mrs_used - dlused);
   1156 
   1157 	if (!DS_UNIQUE_IS_ACCURATE(ds) &&
   1158 	    spa_version(ds->ds_dir->dd_pool->dp_spa) >=
   1159 	    SPA_VERSION_UNIQUE_ACCURATE)
   1160 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
   1161 }
   1162 
   1163 static uint64_t
   1164 dsl_dataset_unique(dsl_dataset_t *ds)
   1165 {
   1166 	if (!DS_UNIQUE_IS_ACCURATE(ds) && !dsl_dataset_is_snapshot(ds))
   1167 		dsl_dataset_recalc_head_uniq(ds);
   1168 
   1169 	return (ds->ds_phys->ds_unique_bytes);
   1170 }
   1171 
   1172 struct killarg {
   1173 	dsl_dataset_t *ds;
   1174 	zio_t *zio;
   1175 	dmu_tx_t *tx;
   1176 };
   1177 
   1178 /* ARGSUSED */
   1179 static int
   1180 kill_blkptr(spa_t *spa, blkptr_t *bp, const zbookmark_t *zb,
   1181     const dnode_phys_t *dnp, void *arg)
   1182 {
   1183 	struct killarg *ka = arg;
   1184 
   1185 	if (bp == NULL)
   1186 		return (0);
   1187 
   1188 	if ((zb->zb_level == -1ULL && zb->zb_blkid != 0) ||
   1189 	    (zb->zb_object != 0 && dnp == NULL)) {
   1190 		/*
   1191 		 * It's a block in the intent log.  It has no
   1192 		 * accounting, so just free it.
   1193 		 */
   1194 		VERIFY3U(0, ==, dsl_free(ka->zio, ka->tx->tx_pool,
   1195 		    ka->tx->tx_txg, bp, NULL, NULL, ARC_NOWAIT));
   1196 	} else {
   1197 		ASSERT3U(bp->blk_birth, >, ka->ds->ds_phys->ds_prev_snap_txg);
   1198 		(void) dsl_dataset_block_kill(ka->ds, bp, ka->zio, ka->tx);
   1199 	}
   1200 
   1201 	return (0);
   1202 }
   1203 
   1204 /* ARGSUSED */
   1205 static int
   1206 dsl_dataset_rollback_check(void *arg1, void *arg2, dmu_tx_t *tx)
   1207 {
   1208 	dsl_dataset_t *ds = arg1;
   1209 	dmu_objset_type_t *ost = arg2;
   1210 
   1211 	/*
   1212 	 * We can only roll back to emptyness if it is a ZPL objset.
   1213 	 */
   1214 	if (*ost != DMU_OST_ZFS &&
   1215 	    ds->ds_phys->ds_prev_snap_txg < TXG_INITIAL)
   1216 		return (EINVAL);
   1217 
   1218 	/*
   1219 	 * This must not be a snapshot.
   1220 	 */
   1221 	if (ds->ds_phys->ds_next_snap_obj != 0)
   1222 		return (EINVAL);
   1223 
   1224 	/*
   1225 	 * If we made changes this txg, traverse_dataset won't find
   1226 	 * them.  Try again.
   1227 	 */
   1228 	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
   1229 		return (EAGAIN);
   1230 
   1231 	return (0);
   1232 }
   1233 
   1234 /* ARGSUSED */
   1235 static void
   1236 dsl_dataset_rollback_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
   1237 {
   1238 	dsl_dataset_t *ds = arg1;
   1239 	dmu_objset_type_t *ost = arg2;
   1240 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
   1241 
   1242 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
   1243 
   1244 	if (ds->ds_user_ptr != NULL) {
   1245 		/*
   1246 		 * We need to make sure that the objset_impl_t is reopened after
   1247 		 * we do the rollback, otherwise it will have the wrong
   1248 		 * objset_phys_t.  Normally this would happen when this
   1249 		 * dataset-open is closed, thus causing the
   1250 		 * dataset to be immediately evicted.  But when doing "zfs recv
   1251 		 * -F", we reopen the objset before that, so that there is no
   1252 		 * window where the dataset is closed and inconsistent.
   1253 		 */
   1254 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
   1255 		ds->ds_user_ptr = NULL;
   1256 	}
   1257 
   1258 	/* Transfer space that was freed since last snap back to the head. */
   1259 	{
   1260 		uint64_t used;
   1261 
   1262 		VERIFY(0 == bplist_space_birthrange(&ds->ds_deadlist,
   1263 		    ds->ds_origin_txg, UINT64_MAX, &used));
   1264 		dsl_dir_transfer_space(ds->ds_dir, used,
   1265 		    DD_USED_SNAP, DD_USED_HEAD, tx);
   1266 	}
   1267 
   1268 	/* Zero out the deadlist. */
   1269 	bplist_close(&ds->ds_deadlist);
   1270 	bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
   1271 	ds->ds_phys->ds_deadlist_obj =
   1272 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
   1273 	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
   1274 	    ds->ds_phys->ds_deadlist_obj));
   1275 
   1276 	{
   1277 		/*
   1278 		 * Free blkptrs that we gave birth to - this covers
   1279 		 * claimed but not played log blocks too.
   1280 		 */
   1281 		zio_t *zio;
   1282 		struct killarg ka;
   1283 
   1284 		zio = zio_root(tx->tx_pool->dp_spa, NULL, NULL,
   1285 		    ZIO_FLAG_MUSTSUCCEED);
   1286 		ka.ds = ds;
   1287 		ka.zio = zio;
   1288 		ka.tx = tx;
   1289 		(void) traverse_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
   1290 		    TRAVERSE_POST, kill_blkptr, &ka);
   1291 		(void) zio_wait(zio);
   1292 	}
   1293 
   1294 	ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) || ds->ds_phys->ds_unique_bytes == 0);
   1295 
   1296 	if (ds->ds_prev && ds->ds_prev != ds->ds_dir->dd_pool->dp_origin_snap) {
   1297 		/* Change our contents to that of the prev snapshot */
   1298 
   1299 		ASSERT3U(ds->ds_prev->ds_object, ==,
   1300 		    ds->ds_phys->ds_prev_snap_obj);
   1301 		ASSERT3U(ds->ds_phys->ds_used_bytes, <=,
   1302 		    ds->ds_prev->ds_phys->ds_used_bytes);
   1303 
   1304 		ds->ds_phys->ds_bp = ds->ds_prev->ds_phys->ds_bp;
   1305 		ds->ds_phys->ds_used_bytes =
   1306 		    ds->ds_prev->ds_phys->ds_used_bytes;
   1307 		ds->ds_phys->ds_compressed_bytes =
   1308 		    ds->ds_prev->ds_phys->ds_compressed_bytes;
   1309 		ds->ds_phys->ds_uncompressed_bytes =
   1310 		    ds->ds_prev->ds_phys->ds_uncompressed_bytes;
   1311 		ds->ds_phys->ds_flags = ds->ds_prev->ds_phys->ds_flags;
   1312 
   1313 		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
   1314 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
   1315 			ds->ds_prev->ds_phys->ds_unique_bytes = 0;
   1316 		}
   1317 	} else {
   1318 		objset_impl_t *osi;
   1319 
   1320 		ASSERT(*ost != DMU_OST_ZVOL);
   1321 		ASSERT3U(ds->ds_phys->ds_used_bytes, ==, 0);
   1322 		ASSERT3U(ds->ds_phys->ds_compressed_bytes, ==, 0);
   1323 		ASSERT3U(ds->ds_phys->ds_uncompressed_bytes, ==, 0);
   1324 
   1325 		bzero(&ds->ds_phys->ds_bp, sizeof (blkptr_t));
   1326 		ds->ds_phys->ds_flags = 0;
   1327 		ds->ds_phys->ds_unique_bytes = 0;
   1328 		if (spa_version(ds->ds_dir->dd_pool->dp_spa) >=
   1329 		    SPA_VERSION_UNIQUE_ACCURATE)
   1330 			ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
   1331 
   1332 		osi = dmu_objset_create_impl(ds->ds_dir->dd_pool->dp_spa, ds,
   1333 		    &ds->ds_phys->ds_bp, *ost, tx);
   1334 #ifdef _KERNEL
   1335 		zfs_create_fs(&osi->os, kcred, NULL, tx);
   1336 #endif
   1337 	}
   1338 
   1339 	spa_history_internal_log(LOG_DS_ROLLBACK, ds->ds_dir->dd_pool->dp_spa,
   1340 	    tx, cr, "dataset = %llu", ds->ds_object);
   1341 }
   1342 
   1343 /* ARGSUSED */
   1344 static int
   1345 dsl_dataset_destroy_begin_check(void *arg1, void *arg2, dmu_tx_t *tx)
   1346 {
   1347 	dsl_dataset_t *ds = arg1;
   1348 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
   1349 	uint64_t count;
   1350 	int err;
   1351 
   1352 	/*
   1353 	 * Can't delete a head dataset if there are snapshots of it.
   1354 	 * (Except if the only snapshots are from the branch we cloned
   1355 	 * from.)
   1356 	 */
   1357 	if (ds->ds_prev != NULL &&
   1358 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
   1359 		return (EINVAL);
   1360 
   1361 	/*
   1362 	 * This is really a dsl_dir thing, but check it here so that
   1363 	 * we'll be less likely to leave this dataset inconsistent &
   1364 	 * nearly destroyed.
   1365 	 */
   1366 	err = zap_count(mos, ds->ds_dir->dd_phys->dd_child_dir_zapobj, &count);
   1367 	if (err)
   1368 		return (err);
   1369 	if (count != 0)
   1370 		return (EEXIST);
   1371 
   1372 	return (0);
   1373 }
   1374 
   1375 /* ARGSUSED */
   1376 static void
   1377 dsl_dataset_destroy_begin_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
   1378 {
   1379 	dsl_dataset_t *ds = arg1;
   1380 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
   1381 
   1382 	/* Mark it as inconsistent on-disk, in case we crash */
   1383 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
   1384 	ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
   1385 
   1386 	spa_history_internal_log(LOG_DS_DESTROY_BEGIN, dp->dp_spa, tx,
   1387 	    cr, "dataset = %llu", ds->ds_object);
   1388 }
   1389 
   1390 /* ARGSUSED */
   1391 int
   1392 dsl_dataset_destroy_check(void *arg1, void *arg2, dmu_tx_t *tx)
   1393 {
   1394 	dsl_dataset_t *ds = arg1;
   1395 
   1396 	/* we have an owner hold, so noone else can destroy us */
   1397 	ASSERT(!DSL_DATASET_IS_DESTROYED(ds));
   1398 
   1399 	/* Can't delete a branch point. */
   1400 	if (ds->ds_phys->ds_num_children > 1)
   1401 		return (EEXIST);
   1402 
   1403 	/*
   1404 	 * Can't delete a head dataset if there are snapshots of it.
   1405 	 * (Except if the only snapshots are from the branch we cloned
   1406 	 * from.)
   1407 	 */
   1408 	if (ds->ds_prev != NULL &&
   1409 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
   1410 		return (EINVAL);
   1411 
   1412 	/*
   1413 	 * If we made changes this txg, traverse_dsl_dataset won't find
   1414 	 * them.  Try again.
   1415 	 */
   1416 	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
   1417 		return (EAGAIN);
   1418 
   1419 	/* XXX we should do some i/o error checking... */
   1420 	return (0);
   1421 }
   1422 
   1423 struct refsarg {
   1424 	kmutex_t lock;
   1425 	boolean_t gone;
   1426 	kcondvar_t cv;
   1427 };
   1428 
   1429 /* ARGSUSED */
   1430 static void
   1431 dsl_dataset_refs_gone(dmu_buf_t *db, void *argv)
   1432 {
   1433 	struct refsarg *arg = argv;
   1434 
   1435 	mutex_enter(&arg->lock);
   1436 	arg->gone = TRUE;
   1437 	cv_signal(&arg->cv);
   1438 	mutex_exit(&arg->lock);
   1439 }
   1440 
   1441 static void
   1442 dsl_dataset_drain_refs(dsl_dataset_t *ds, void *tag)
   1443 {
   1444 	struct refsarg arg;
   1445 
   1446 	mutex_init(&arg.lock, NULL, MUTEX_DEFAULT, NULL);
   1447 	cv_init(&arg.cv, NULL, CV_DEFAULT, NULL);
   1448 	arg.gone = FALSE;
   1449 	(void) dmu_buf_update_user(ds->ds_dbuf, ds, &arg, &ds->ds_phys,
   1450 	    dsl_dataset_refs_gone);
   1451 	dmu_buf_rele(ds->ds_dbuf, tag);
   1452 	mutex_enter(&arg.lock);
   1453 	while (!arg.gone)
   1454 		cv_wait(&arg.cv, &arg.lock);
   1455 	ASSERT(arg.gone);
   1456 	mutex_exit(&arg.lock);
   1457 	ds->ds_dbuf = NULL;
   1458 	ds->ds_phys = NULL;
   1459 	mutex_destroy(&arg.lock);
   1460 	cv_destroy(&arg.cv);
   1461 }
   1462 
   1463 void
   1464 dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
   1465 {
   1466 	dsl_dataset_t *ds = arg1;
   1467 	zio_t *zio;
   1468 	int err;
   1469 	int after_branch_point = FALSE;
   1470 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
   1471 	objset_t *mos = dp->dp_meta_objset;
   1472 	dsl_dataset_t *ds_prev = NULL;
   1473 	uint64_t obj;
   1474 
   1475 	ASSERT(ds->ds_owner);
   1476 	ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
   1477 	ASSERT(ds->ds_prev == NULL ||
   1478 	    ds->ds_prev->ds_phys->ds_next_snap_obj != ds->ds_object);
   1479 	ASSERT3U(ds->ds_phys->ds_bp.blk_birth, <=, tx->tx_txg);
   1480 
   1481 	/* signal any waiters that this dataset is going away */
   1482 	mutex_enter(&ds->ds_lock);
   1483 	ds->ds_owner = dsl_reaper;
   1484 	cv_broadcast(&ds->ds_exclusive_cv);
   1485 	mutex_exit(&ds->ds_lock);
   1486 
   1487 	/* Remove our reservation */
   1488 	if (ds->ds_reserved != 0) {
   1489 		uint64_t val = 0;
   1490 		dsl_dataset_set_reservation_sync(ds, &val, cr, tx);
   1491 		ASSERT3U(ds->ds_reserved, ==, 0);
   1492 	}
   1493 
   1494 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
   1495 
   1496 	dsl_pool_ds_destroyed(ds, tx);
   1497 
   1498 	obj = ds->ds_object;
   1499 
   1500 	if (ds->ds_phys->ds_prev_snap_obj != 0) {
   1501 		if (ds->ds_prev) {
   1502 			ds_prev = ds->ds_prev;
   1503 		} else {
   1504 			VERIFY(0 == dsl_dataset_hold_obj(dp,
   1505 			    ds->ds_phys->ds_prev_snap_obj, FTAG, &ds_prev));
   1506 		}
   1507 		after_branch_point =
   1508 		    (ds_prev->ds_phys->ds_next_snap_obj != obj);
   1509 
   1510 		dmu_buf_will_dirty(ds_prev->ds_dbuf, tx);
   1511 		if (after_branch_point &&
   1512 		    ds_prev->ds_phys->ds_next_clones_obj != 0) {
   1513 			VERIFY3U(0, ==, zap_remove_int(mos,
   1514 			    ds_prev->ds_phys->ds_next_clones_obj, obj, tx));
   1515 			if (ds->ds_phys->ds_next_snap_obj != 0) {
   1516 				VERIFY(0 == zap_add_int(mos,
   1517 				    ds_prev->ds_phys->ds_next_clones_obj,
   1518 				    ds->ds_phys->ds_next_snap_obj, tx));
   1519 			}
   1520 		}
   1521 		if (after_branch_point &&
   1522 		    ds->ds_phys->ds_next_snap_obj == 0) {
   1523 			/* This clone is toast. */
   1524 			ASSERT(ds_prev->ds_phys->ds_num_children > 1);
   1525 			ds_prev->ds_phys->ds_num_children--;
   1526 		} else if (!after_branch_point) {
   1527 			ds_prev->ds_phys->ds_next_snap_obj =
   1528 			    ds->ds_phys->ds_next_snap_obj;
   1529 		}
   1530 	}
   1531 
   1532 	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
   1533 
   1534 	if (ds->ds_phys->ds_next_snap_obj != 0) {
   1535 		blkptr_t bp;
   1536 		dsl_dataset_t *ds_next;
   1537 		uint64_t itor = 0;
   1538 		uint64_t old_unique;
   1539 		int64_t used = 0, compressed = 0, uncompressed = 0;
   1540 
   1541 		VERIFY(0 == dsl_dataset_hold_obj(dp,
   1542 		    ds->ds_phys->ds_next_snap_obj, FTAG, &ds_next));
   1543 		ASSERT3U(ds_next->ds_phys->ds_prev_snap_obj, ==, obj);
   1544 
   1545 		old_unique = dsl_dataset_unique(ds_next);
   1546 
   1547 		dmu_buf_will_dirty(ds_next->ds_dbuf, tx);
   1548 		ds_next->ds_phys->ds_prev_snap_obj =
   1549 		    ds->ds_phys->ds_prev_snap_obj;
   1550 		ds_next->ds_phys->ds_prev_snap_txg =
   1551 		    ds->ds_phys->ds_prev_snap_txg;
   1552 		ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
   1553 		    ds_prev ? ds_prev->ds_phys->ds_creation_txg : 0);
   1554 
   1555 		/*
   1556 		 * Transfer to our deadlist (which will become next's
   1557 		 * new deadlist) any entries from next's current
   1558 		 * deadlist which were born before prev, and free the
   1559 		 * other entries.
   1560 		 *
   1561 		 * XXX we're doing this long task with the config lock held
   1562 		 */
   1563 		while (bplist_iterate(&ds_next->ds_deadlist, &itor, &bp) == 0) {
   1564 			if (bp.blk_birth <= ds->ds_phys->ds_prev_snap_txg) {
   1565 				VERIFY(0 == bplist_enqueue(&ds->ds_deadlist,
   1566 				    &bp, tx));
   1567 				if (ds_prev && !after_branch_point &&
   1568 				    bp.blk_birth >
   1569 				    ds_prev->ds_phys->ds_prev_snap_txg) {
   1570 					ds_prev->ds_phys->ds_unique_bytes +=
   1571 					    bp_get_dasize(dp->dp_spa, &bp);
   1572 				}
   1573 			} else {
   1574 				used += bp_get_dasize(dp->dp_spa, &bp);
   1575 				compressed += BP_GET_PSIZE(&bp);
   1576 				uncompressed += BP_GET_UCSIZE(&bp);
   1577 				/* XXX check return value? */
   1578 				(void) dsl_free(zio, dp, tx->tx_txg,
   1579 				    &bp, NULL, NULL, ARC_NOWAIT);
   1580 			}
   1581 		}
   1582 
   1583 		ASSERT3U(used, ==, ds->ds_phys->ds_unique_bytes);
   1584 
   1585 		/* change snapused */
   1586 		dsl_dir_diduse_space(ds->ds_dir, DD_USED_SNAP,
   1587 		    -used, -compressed, -uncompressed, tx);
   1588 
   1589 		/* free next's deadlist */
   1590 		bplist_close(&ds_next->ds_deadlist);
   1591 		bplist_destroy(mos, ds_next->ds_phys->ds_deadlist_obj, tx);
   1592 
   1593 		/* set next's deadlist to our deadlist */
   1594 		bplist_close(&ds->ds_deadlist);
   1595 		ds_next->ds_phys->ds_deadlist_obj =
   1596 		    ds->ds_phys->ds_deadlist_obj;
   1597 		VERIFY(0 == bplist_open(&ds_next->ds_deadlist, mos,
   1598 		    ds_next->ds_phys->ds_deadlist_obj));
   1599 		ds->ds_phys->ds_deadlist_obj = 0;
   1600 
   1601 		if (ds_next->ds_phys->ds_next_snap_obj != 0) {
   1602 			/*
   1603 			 * Update next's unique to include blocks which
   1604 			 * were previously shared by only this snapshot
   1605 			 * and it.  Those blocks will be born after the
   1606 			 * prev snap and before this snap, and will have
   1607 			 * died after the next snap and before the one
   1608 			 * after that (ie. be on the snap after next's
   1609 			 * deadlist).
   1610 			 *
   1611 			 * XXX we're doing this long task with the
   1612 			 * config lock held
   1613 			 */
   1614 			dsl_dataset_t *ds_after_next;
   1615 			uint64_t space;
   1616 
   1617 			VERIFY(0 == dsl_dataset_hold_obj(dp,
   1618 			    ds_next->ds_phys->ds_next_snap_obj,
   1619 			    FTAG, &ds_after_next));
   1620 
   1621 			VERIFY(0 ==
   1622 			    bplist_space_birthrange(&ds_after_next->ds_deadlist,
   1623 			    ds->ds_phys->ds_prev_snap_txg,
   1624 			    ds->ds_phys->ds_creation_txg, &space));
   1625 			ds_next->ds_phys->ds_unique_bytes += space;
   1626 
   1627 			dsl_dataset_rele(ds_after_next, FTAG);
   1628 			ASSERT3P(ds_next->ds_prev, ==, NULL);
   1629 		} else {
   1630 			ASSERT3P(ds_next->ds_prev, ==, ds);
   1631 			dsl_dataset_drop_ref(ds_next->ds_prev, ds_next);
   1632 			ds_next->ds_prev = NULL;
   1633 			if (ds_prev) {
   1634 				VERIFY(0 == dsl_dataset_get_ref(dp,
   1635 				    ds->ds_phys->ds_prev_snap_obj,
   1636 				    ds_next, &ds_next->ds_prev));
   1637 			}
   1638 
   1639 			dsl_dataset_recalc_head_uniq(ds_next);
   1640 
   1641 			/*
   1642 			 * Reduce the amount of our unconsmed refreservation
   1643 			 * being charged to our parent by the amount of
   1644 			 * new unique data we have gained.
   1645 			 */
   1646 			if (old_unique < ds_next->ds_reserved) {
   1647 				int64_t mrsdelta;
   1648 				uint64_t new_unique =
   1649 				    ds_next->ds_phys->ds_unique_bytes;
   1650 
   1651 				ASSERT(old_unique <= new_unique);
   1652 				mrsdelta = MIN(new_unique - old_unique,
   1653 				    ds_next->ds_reserved - old_unique);
   1654 				dsl_dir_diduse_space(ds->ds_dir,
   1655 				    DD_USED_REFRSRV, -mrsdelta, 0, 0, tx);
   1656 			}
   1657 		}
   1658 		dsl_dataset_rele(ds_next, FTAG);
   1659 	} else {
   1660 		/*
   1661 		 * There's no next snapshot, so this is a head dataset.
   1662 		 * Destroy the deadlist.  Unless it's a clone, the
   1663 		 * deadlist should be empty.  (If it's a clone, it's
   1664 		 * safe to ignore the deadlist contents.)
   1665 		 */
   1666 		struct killarg ka;
   1667 
   1668 		ASSERT(after_branch_point || bplist_empty(&ds->ds_deadlist));
   1669 		bplist_close(&ds->ds_deadlist);
   1670 		bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
   1671 		ds->ds_phys->ds_deadlist_obj = 0;
   1672 
   1673 		/*
   1674 		 * Free everything that we point to (that's born after
   1675 		 * the previous snapshot, if we are a clone)
   1676 		 *
   1677 		 * NB: this should be very quick, because we already
   1678 		 * freed all the objects in open context.
   1679 		 */
   1680 		ka.ds = ds;
   1681 		ka.zio = zio;
   1682 		ka.tx = tx;
   1683 		err = traverse_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
   1684 		    TRAVERSE_POST, kill_blkptr, &ka);
   1685 		ASSERT3U(err, ==, 0);
   1686 		ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) ||
   1687 		    ds->ds_phys->ds_unique_bytes == 0);
   1688 	}
   1689 
   1690 	err = zio_wait(zio);
   1691 	ASSERT3U(err, ==, 0);
   1692 
   1693 	if (ds->ds_dir->dd_phys->dd_head_dataset_obj == ds->ds_object) {
   1694 		/* Erase the link in the dir */
   1695 		dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
   1696 		ds->ds_dir->dd_phys->dd_head_dataset_obj = 0;
   1697 		ASSERT(ds->ds_phys->ds_snapnames_zapobj != 0);
   1698 		err = zap_destroy(mos, ds->ds_phys->ds_snapnames_zapobj, tx);
   1699 		ASSERT(err == 0);
   1700 	} else {
   1701 		/* remove from snapshot namespace */
   1702 		dsl_dataset_t *ds_head;
   1703 		ASSERT(ds->ds_phys->ds_snapnames_zapobj == 0);
   1704 		VERIFY(0 == dsl_dataset_hold_obj(dp,
   1705 		    ds->ds_dir->dd_phys->dd_head_dataset_obj, FTAG, &ds_head));
   1706 		VERIFY(0 == dsl_dataset_get_snapname(ds));
   1707 #ifdef ZFS_DEBUG
   1708 		{
   1709 			uint64_t val;
   1710 
   1711 			err = dsl_dataset_snap_lookup(ds_head,
   1712 			    ds->ds_snapname, &val);
   1713 			ASSERT3U(err, ==, 0);
   1714 			ASSERT3U(val, ==, obj);
   1715 		}
   1716 #endif
   1717 		err = dsl_dataset_snap_remove(ds_head, ds->ds_snapname, tx);
   1718 		ASSERT(err == 0);
   1719 		dsl_dataset_rele(ds_head, FTAG);
   1720 	}
   1721 
   1722 	if (ds_prev && ds->ds_prev != ds_prev)
   1723 		dsl_dataset_rele(ds_prev, FTAG);
   1724 
   1725 	spa_prop_clear_bootfs(dp->dp_spa, ds->ds_object, tx);
   1726 	spa_history_internal_log(LOG_DS_DESTROY, dp->dp_spa, tx,
   1727 	    cr, "dataset = %llu", ds->ds_object);
   1728 
   1729 	if (ds->ds_phys->ds_next_clones_obj != 0) {
   1730 		uint64_t count;
   1731 		ASSERT(0 == zap_count(mos,
   1732 		    ds->ds_phys->ds_next_clones_obj, &count) && count == 0);
   1733 		VERIFY(0 == dmu_object_free(mos,
   1734 		    ds->ds_phys->ds_next_clones_obj, tx));
   1735 	}
   1736 	if (ds->ds_phys->ds_props_obj != 0)
   1737 		VERIFY(0 == zap_destroy(mos, ds->ds_phys->ds_props_obj, tx));
   1738 	dsl_dir_close(ds->ds_dir, ds);
   1739 	ds->ds_dir = NULL;
   1740 	dsl_dataset_drain_refs(ds, tag);
   1741 	VERIFY(0 == dmu_object_free(mos, obj, tx));
   1742 }
   1743 
   1744 static int
   1745 dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
   1746 {
   1747 	uint64_t asize;
   1748 
   1749 	if (!dmu_tx_is_syncing(tx))
   1750 		return (0);
   1751 
   1752 	/*
   1753 	 * If there's an fs-only reservation, any blocks that might become
   1754 	 * owned by the snapshot dataset must be accommodated by space
   1755 	 * outside of the reservation.
   1756 	 */
   1757 	asize = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
   1758 	if (asize > dsl_dir_space_available(ds->ds_dir, NULL, 0, FALSE))
   1759 		return (ENOSPC);
   1760 
   1761 	/*
   1762 	 * Propogate any reserved space for this snapshot to other
   1763 	 * snapshot checks in this sync group.
   1764 	 */
   1765 	if (asize > 0)
   1766 		dsl_dir_willuse_space(ds->ds_dir, asize, tx);
   1767 
   1768 	return (0);
   1769 }
   1770 
   1771 /* ARGSUSED */
   1772 int
   1773 dsl_dataset_snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
   1774 {
   1775 	dsl_dataset_t *ds = arg1;
   1776 	const char *snapname = arg2;
   1777 	int err;
   1778 	uint64_t value;
   1779 
   1780 	/*
   1781 	 * We don't allow multiple snapshots of the same txg.  If there
   1782 	 * is already one, try again.
   1783 	 */
   1784 	if (ds->ds_phys->ds_prev_snap_txg >= tx->tx_txg)
   1785 		return (EAGAIN);
   1786 
   1787 	/*
   1788 	 * Check for conflicting name snapshot name.
   1789 	 */
   1790 	err = dsl_dataset_snap_lookup(ds, snapname, &value);
   1791 	if (err == 0)
   1792 		return (EEXIST);
   1793 	if (err != ENOENT)
   1794 		return (err);
   1795 
   1796 	/*
   1797 	 * Check that the dataset's name is not too long.  Name consists
   1798 	 * of the dataset's length + 1 for the @-sign + snapshot name's length
   1799 	 */
   1800 	if (dsl_dataset_namelen(ds) + 1 + strlen(snapname) >= MAXNAMELEN)
   1801 		return (ENAMETOOLONG);
   1802 
   1803 	err = dsl_dataset_snapshot_reserve_space(ds, tx);
   1804 	if (err)
   1805 		return (err);
   1806 
   1807 	ds->ds_trysnap_txg = tx->tx_txg;
   1808 	return (0);
   1809 }
   1810 
   1811 void
   1812 dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
   1813 {
   1814 	dsl_dataset_t *ds = arg1;
   1815 	const char *snapname = arg2;
   1816 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
   1817 	dmu_buf_t *dbuf;
   1818 	dsl_dataset_phys_t *dsphys;
   1819 	uint64_t dsobj, crtxg;
   1820 	objset_t *mos = dp->dp_meta_objset;
   1821 	int err;
   1822 
   1823 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
   1824 
   1825 	/*
   1826 	 * The origin's ds_creation_txg has to be < TXG_INITIAL
   1827 	 */
   1828 	if (strcmp(snapname, ORIGIN_DIR_NAME) == 0)
   1829 		crtxg = 1;
   1830 	else
   1831 		crtxg = tx->tx_txg;
   1832 
   1833 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
   1834 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
   1835 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
   1836 	dmu_buf_will_dirty(dbuf, tx);
   1837 	dsphys = dbuf->db_data;
   1838 	bzero(dsphys, sizeof (dsl_dataset_phys_t));
   1839 	dsphys->ds_dir_obj = ds->ds_dir->dd_object;
   1840 	dsphys->ds_fsid_guid = unique_create();
   1841 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
   1842 	    sizeof (dsphys->ds_guid));
   1843 	dsphys->ds_prev_snap_obj = ds->ds_phys->ds_prev_snap_obj;
   1844 	dsphys->ds_prev_snap_txg = ds->ds_phys->ds_prev_snap_txg;
   1845 	dsphys->ds_next_snap_obj = ds->ds_object;
   1846 	dsphys->ds_num_children = 1;
   1847 	dsphys->ds_creation_time = gethrestime_sec();
   1848 	dsphys->ds_creation_txg = crtxg;
   1849 	dsphys->ds_deadlist_obj = ds->ds_phys->ds_deadlist_obj;
   1850 	dsphys->ds_used_bytes = ds->ds_phys->ds_used_bytes;
   1851 	dsphys->ds_compressed_bytes = ds->ds_phys->ds_compressed_bytes;
   1852 	dsphys->ds_uncompressed_bytes = ds->ds_phys->ds_uncompressed_bytes;
   1853 	dsphys->ds_flags = ds->ds_phys->ds_flags;
   1854 	dsphys->ds_bp = ds->ds_phys->ds_bp;
   1855 	dmu_buf_rele(dbuf, FTAG);
   1856 
   1857 	ASSERT3U(ds->ds_prev != 0, ==, ds->ds_phys->ds_prev_snap_obj != 0);
   1858 	if (ds->ds_prev) {
   1859 		uint64_t next_clones_obj =
   1860 		    ds->ds_prev->ds_phys->ds_next_clones_obj;
   1861 		ASSERT(ds->ds_prev->ds_phys->ds_next_snap_obj ==
   1862 		    ds->ds_object ||
   1863 		    ds->ds_prev->ds_phys->ds_num_children > 1);
   1864 		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
   1865 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
   1866 			ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
   1867 			    ds->ds_prev->ds_phys->ds_creation_txg);
   1868 			ds->ds_prev->ds_phys->ds_next_snap_obj = dsobj;
   1869 		} else if (next_clones_obj != 0) {
   1870 			VERIFY3U(0, ==, zap_remove_int(mos,
   1871 			    next_clones_obj, dsphys->ds_next_snap_obj, tx));
   1872 			VERIFY3U(0, ==, zap_add_int(mos,
   1873 			    next_clones_obj, dsobj, tx));
   1874 		}
   1875 	}
   1876 
   1877 	/*
   1878 	 * If we have a reference-reservation on this dataset, we will
   1879 	 * need to increase the amount of refreservation being charged
   1880 	 * since our unique space is going to zero.
   1881 	 */
   1882 	if (ds->ds_reserved) {
   1883 		int64_t add = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
   1884 		dsl_dir_diduse_space(ds->ds_dir, DD_USED_REFRSRV,
   1885 		    add, 0, 0, tx);
   1886 	}
   1887 
   1888 	bplist_close(&ds->ds_deadlist);
   1889 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
   1890 	ASSERT3U(ds->ds_phys->ds_prev_snap_txg, <, tx->tx_txg);
   1891 	ds->ds_phys->ds_prev_snap_obj = dsobj;
   1892 	ds->ds_phys->ds_prev_snap_txg = crtxg;
   1893 	ds->ds_phys->ds_unique_bytes = 0;
   1894 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
   1895 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
   1896 	ds->ds_phys->ds_deadlist_obj =
   1897 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
   1898 	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
   1899 	    ds->ds_phys->ds_deadlist_obj));
   1900 
   1901 	dprintf("snap '%s' -> obj %llu\n", snapname, dsobj);
   1902 	err = zap_add(mos, ds->ds_phys->ds_snapnames_zapobj,
   1903 	    snapname, 8, 1, &dsobj, tx);
   1904 	ASSERT(err == 0);
   1905 
   1906 	if (ds->ds_prev)
   1907 		dsl_dataset_drop_ref(ds->ds_prev, ds);
   1908 	VERIFY(0 == dsl_dataset_get_ref(dp,
   1909 	    ds->ds_phys->ds_prev_snap_obj, ds, &ds->ds_prev));
   1910 
   1911 	dsl_pool_ds_snapshotted(ds, tx);
   1912 
   1913 	spa_history_internal_log(LOG_DS_SNAPSHOT, dp->dp_spa, tx, cr,
   1914 	    "dataset = %llu", dsobj);
   1915 }
   1916 
   1917 void
   1918 dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
   1919 {
   1920 	ASSERT(dmu_tx_is_syncing(tx));
   1921 	ASSERT(ds->ds_user_ptr != NULL);
   1922 	ASSERT(ds->ds_phys->ds_next_snap_obj == 0);
   1923 
   1924 	/*
   1925 	 * in case we had to change ds_fsid_guid when we opened it,
   1926 	 * sync it out now.
   1927 	 */
   1928 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
   1929 	ds->ds_phys->ds_fsid_guid = ds->ds_fsid_guid;
   1930 
   1931 	dsl_dir_dirty(ds->ds_dir, tx);
   1932 	dmu_objset_sync(ds->ds_user_ptr, zio, tx);
   1933 }
   1934 
   1935 void
   1936 dsl_dataset_stats(dsl_dataset_t *ds, nvlist_t *nv)
   1937 {
   1938 	uint64_t refd, avail, uobjs, aobjs;
   1939 
   1940 	dsl_dir_stats(ds->ds_dir, nv);
   1941 
   1942 	dsl_dataset_space(ds, &refd, &avail, &uobjs, &aobjs);
   1943 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_AVAILABLE, avail);
   1944 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFERENCED, refd);
   1945 
   1946 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATION,
   1947 	    ds->ds_phys->ds_creation_time);
   1948 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATETXG,
   1949 	    ds->ds_phys->ds_creation_txg);
   1950 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFQUOTA,
   1951 	    ds->ds_quota);
   1952 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFRESERVATION,
   1953 	    ds->ds_reserved);
   1954 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_GUID,
   1955 	    ds->ds_phys->ds_guid);
   1956 
   1957 	if (ds->ds_phys->ds_next_snap_obj) {
   1958 		/*
   1959 		 * This is a snapshot; override the dd's space used with
   1960 		 * our unique space and compression ratio.
   1961 		 */
   1962 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
   1963 		    ds->ds_phys->ds_unique_bytes);
   1964 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
   1965 		    ds->ds_phys->ds_compressed_bytes == 0 ? 100 :
   1966 		    (ds->ds_phys->ds_uncompressed_bytes * 100 /
   1967 		    ds->ds_phys->ds_compressed_bytes));
   1968 	}
   1969 }
   1970 
   1971 void
   1972 dsl_dataset_fast_stat(dsl_dataset_t *ds, dmu_objset_stats_t *stat)
   1973 {
   1974 	stat->dds_creation_txg = ds->ds_phys->ds_creation_txg;
   1975 	stat->dds_inconsistent = ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT;
   1976 	stat->dds_guid = ds->ds_phys->ds_guid;
   1977 	if (ds->ds_phys->ds_next_snap_obj) {
   1978 		stat->dds_is_snapshot = B_TRUE;
   1979 		stat->dds_num_clones = ds->ds_phys->ds_num_children - 1;
   1980 	} else {
   1981 		stat->dds_is_snapshot = B_FALSE;
   1982 		stat->dds_num_clones = 0;
   1983 	}
   1984 
   1985 	/* clone origin is really a dsl_dir thing... */
   1986 	rw_enter(&ds->ds_dir->dd_pool->dp_config_rwlock, RW_READER);
   1987 	if (dsl_dir_is_clone(ds->ds_dir)) {
   1988 		dsl_dataset_t *ods;
   1989 
   1990 		VERIFY(0 == dsl_dataset_get_ref(ds->ds_dir->dd_pool,
   1991 		    ds->ds_dir->dd_phys->dd_origin_obj, FTAG, &ods));
   1992 		dsl_dataset_name(ods, stat->dds_origin);
   1993 		dsl_dataset_drop_ref(ods, FTAG);
   1994 	} else {
   1995 		stat->dds_origin[0] = '\0';
   1996 	}
   1997 	rw_exit(&ds->ds_dir->dd_pool->dp_config_rwlock);
   1998 }
   1999 
   2000 uint64_t
   2001 dsl_dataset_fsid_guid(dsl_dataset_t *ds)
   2002 {
   2003 	return (ds->ds_fsid_guid);
   2004 }
   2005 
   2006 void
   2007 dsl_dataset_space(dsl_dataset_t *ds,
   2008     uint64_t *refdbytesp, uint64_t *availbytesp,
   2009     uint64_t *usedobjsp, uint64_t *availobjsp)
   2010 {
   2011 	*refdbytesp = ds->ds_phys->ds_used_bytes;
   2012 	*availbytesp = dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE);
   2013 	if (ds->ds_reserved > ds->ds_phys->ds_unique_bytes)
   2014 		*availbytesp += ds->ds_reserved - ds->ds_phys->ds_unique_bytes;
   2015 	if (ds->ds_quota != 0) {
   2016 		/*
   2017 		 * Adjust available bytes according to refquota
   2018 		 */
   2019 		if (*refdbytesp < ds->ds_quota)
   2020 			*availbytesp = MIN(*availbytesp,
   2021 			    ds->ds_quota - *refdbytesp);
   2022 		else
   2023 			*availbytesp = 0;
   2024 	}
   2025 	*usedobjsp = ds->ds_phys->ds_bp.blk_fill;
   2026 	*availobjsp = DN_MAX_OBJECT - *usedobjsp;
   2027 }
   2028 
   2029 boolean_t
   2030 dsl_dataset_modified_since_lastsnap(dsl_dataset_t *ds)
   2031 {
   2032 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
   2033 
   2034 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
   2035 	    dsl_pool_sync_context(dp));
   2036 	if (ds->ds_prev == NULL)
   2037 		return (B_FALSE);
   2038 	if (ds->ds_phys->ds_bp.blk_birth >
   2039 	    ds->ds_prev->ds_phys->ds_creation_txg)
   2040 		return (B_TRUE);
   2041 	return (B_FALSE);
   2042 }
   2043 
   2044 /* ARGSUSED */
   2045 static int
   2046 dsl_dataset_snapshot_rename_check(void *arg1, void *arg2, dmu_tx_t *tx)
   2047 {
   2048 	dsl_dataset_t *ds = arg1;
   2049 	char *newsnapname = arg2;
   2050 	dsl_dir_t *dd = ds->ds_dir;
   2051 	dsl_dataset_t *hds;
   2052 	uint64_t val;
   2053 	int err;
   2054 
   2055 	err = dsl_dataset_hold_obj(dd->dd_pool,
   2056 	    dd->dd_phys->dd_head_dataset_obj, FTAG, &hds);
   2057 	if (err)
   2058 		return (err);
   2059 
   2060 	/* new name better not be in use */
   2061 	err = dsl_dataset_snap_lookup(hds, newsnapname, &val);
   2062 	dsl_dataset_rele(hds, FTAG);
   2063 
   2064 	if (err == 0)
   2065 		err = EEXIST;
   2066 	else if (err == ENOENT)
   2067 		err = 0;
   2068 
   2069 	/* dataset name + 1 for the "@" + the new snapshot name must fit */
   2070 	if (dsl_dir_namelen(ds->ds_dir) + 1 + strlen(newsnapname) >= MAXNAMELEN)
   2071 		err = ENAMETOOLONG;
   2072 
   2073 	return (err);
   2074 }
   2075 
   2076 static void
   2077 dsl_dataset_snapshot_rename_sync(void *arg1, void *arg2,
   2078     cred_t *cr, dmu_tx_t *tx)
   2079 {
   2080 	dsl_dataset_t *ds = arg1;
   2081 	const char *newsnapname = arg2;
   2082 	dsl_dir_t *dd = ds->ds_dir;
   2083 	objset_t *mos = dd->dd_pool->dp_meta_objset;
   2084 	dsl_dataset_t *hds;
   2085 	int err;
   2086 
   2087 	ASSERT(ds->ds_phys->ds_next_snap_obj != 0);
   2088 
   2089 	VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool,
   2090 	    dd->dd_phys->dd_head_dataset_obj, FTAG, &hds));
   2091 
   2092 	VERIFY(0 == dsl_dataset_get_snapname(ds));
   2093 	err = dsl_dataset_snap_remove(hds, ds->ds_snapname, tx);
   2094 	ASSERT3U(err, ==, 0);
   2095 	mutex_enter(&ds->ds_lock);
   2096 	(void) strcpy(ds->ds_snapname, newsnapname);
   2097 	mutex_exit(&ds->ds_lock);
   2098 	err = zap_add(mos, hds->ds_phys->ds_snapnames_zapobj,
   2099 	    ds->ds_snapname, 8, 1, &ds->ds_object, tx);
   2100 	ASSERT3U(err, ==, 0);
   2101 
   2102 	spa_history_internal_log(LOG_DS_RENAME, dd->dd_pool->dp_spa, tx,
   2103 	    cr, "dataset = %llu", ds->ds_object);
   2104 	dsl_dataset_rele(hds, FTAG);
   2105 }
   2106 
   2107 struct renamesnaparg {
   2108 	dsl_sync_task_group_t *dstg;
   2109 	char failed[MAXPATHLEN];
   2110 	char *oldsnap;
   2111 	char *newsnap;
   2112 };
   2113 
   2114 static int
   2115 dsl_snapshot_rename_one(char *name, void *arg)
   2116 {
   2117 	struct renamesnaparg *ra = arg;
   2118 	dsl_dataset_t *ds = NULL;
   2119 	char *cp;
   2120 	int err;
   2121 
   2122 	cp = name + strlen(name);
   2123 	*cp = '@';
   2124 	(void) strcpy(cp + 1, ra->oldsnap);
   2125 
   2126 	/*
   2127 	 * For recursive snapshot renames the parent won't be changing
   2128 	 * so we just pass name for both the to/from argument.
   2129 	 */
   2130 	err = zfs_secpolicy_rename_perms(name, name, CRED());
   2131 	if (err == ENOENT) {
   2132 		return (0);
   2133 	} else if (err) {
   2134 		(void) strcpy(ra->failed, name);
   2135 		return (err);
   2136 	}
   2137 
   2138 #ifdef _KERNEL
   2139 	/*
   2140 	 * For all filesystems undergoing rename, we'll need to unmount it.
   2141 	 */
   2142 	(void) zfs_unmount_snap(name, NULL);
   2143 #endif
   2144 	err = dsl_dataset_hold(name, ra->dstg, &ds);
   2145 	*cp = '\0';
   2146 	if (err == ENOENT) {
   2147 		return (0);
   2148 	} else if (err) {
   2149 		(void) strcpy(ra->failed, name);
   2150 		return (err);
   2151 	}
   2152 
   2153 	dsl_sync_task_create(ra->dstg, dsl_dataset_snapshot_rename_check,
   2154 	    dsl_dataset_snapshot_rename_sync, ds, ra->newsnap, 0);
   2155 
   2156 	return (0);
   2157 }
   2158 
   2159 static int
   2160 dsl_recursive_rename(char *oldname, const char *newname)
   2161 {
   2162 	int err;
   2163 	struct renamesnaparg *ra;
   2164 	dsl_sync_task_t *dst;
   2165 	spa_t *spa;
   2166 	char *cp, *fsname = spa_strdup(oldname);
   2167 	int len = strlen(oldname);
   2168 
   2169 	/* truncate the snapshot name to get the fsname */
   2170 	cp = strchr(fsname, '@');
   2171 	*cp = '\0';
   2172 
   2173 	err = spa_open(fsname, &spa, FTAG);
   2174 	if (err) {
   2175 		kmem_free(fsname, len + 1);
   2176 		return (err);
   2177 	}
   2178 	ra = kmem_alloc(sizeof (struct renamesnaparg), KM_SLEEP);
   2179 	ra->dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
   2180 
   2181 	ra->oldsnap = strchr(oldname, '@') + 1;
   2182 	ra->newsnap = strchr(newname, '@') + 1;
   2183 	*ra->failed = '\0';
   2184 
   2185 	err = dmu_objset_find(fsname, dsl_snapshot_rename_one, ra,
   2186 	    DS_FIND_CHILDREN);
   2187 	kmem_free(fsname, len + 1);
   2188 
   2189 	if (err == 0) {
   2190 		err = dsl_sync_task_group_wait(ra->dstg);
   2191 	}
   2192 
   2193 	for (dst = list_head(&ra->dstg->dstg_tasks); dst;
   2194 	    dst = list_next(&ra->dstg->dstg_tasks, dst)) {
   2195 		dsl_dataset_t *ds = dst->dst_arg1;
   2196 		if (dst->dst_err) {
   2197 			dsl_dir_name(ds->ds_dir, ra->failed);
   2198 			(void) strcat(ra->failed, "@");
   2199 			(void) strcat(ra->failed, ra->newsnap);
   2200 		}
   2201 		dsl_dataset_rele(ds, ra->dstg);
   2202 	}
   2203 
   2204 	if (err)
   2205 		(void) strcpy(oldname, ra->failed);
   2206 
   2207 	dsl_sync_task_group_destroy(ra->dstg);
   2208 	kmem_free(ra, sizeof (struct renamesnaparg));
   2209 	spa_close(spa, FTAG);
   2210 	return (err);
   2211 }
   2212 
   2213 static int
   2214 dsl_valid_rename(char *oldname, void *arg)
   2215 {
   2216 	int delta = *(int *)arg;
   2217 
   2218 	if (strlen(oldname) + delta >= MAXNAMELEN)
   2219 		return (ENAMETOOLONG);
   2220 
   2221 	return (0);
   2222 }
   2223 
   2224 #pragma weak dmu_objset_rename = dsl_dataset_rename
   2225 int
   2226 dsl_dataset_rename(char *oldname, const char *newname, boolean_t recursive)
   2227 {
   2228 	dsl_dir_t *dd;
   2229 	dsl_dataset_t *ds;
   2230 	const char *tail;
   2231 	int err;
   2232 
   2233 	err = dsl_dir_open(oldname, FTAG, &dd, &tail);
   2234 	if (err)
   2235 		return (err);
   2236 	/*
   2237 	 * If there are more than 2 references there may be holds
   2238 	 * hanging around that haven't been cleared out yet.
   2239 	 */
   2240 	if (dmu_buf_refcount(dd->dd_dbuf) > 2)
   2241 		txg_wait_synced(dd->dd_pool, 0);
   2242 	if (tail == NULL) {
   2243 		int delta = strlen(newname) - strlen(oldname);
   2244 
   2245 		/* if we're growing, validate child name lengths */
   2246 		if (delta > 0)
   2247 			err = dmu_objset_find(oldname, dsl_valid_rename,
   2248 			    &delta, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
   2249 
   2250 		if (!err)
   2251 			err = dsl_dir_rename(dd, newname);
   2252 		dsl_dir_close(dd, FTAG);
   2253 		return (err);
   2254 	}
   2255 	if (tail[0] != '@') {
   2256 		/* the name ended in a nonexistant component */
   2257 		dsl_dir_close(dd, FTAG);
   2258 		return (ENOENT);
   2259 	}
   2260 
   2261 	dsl_dir_close(dd, FTAG);
   2262 
   2263 	/* new name must be snapshot in same filesystem */
   2264 	tail = strchr(newname, '@');
   2265 	if (tail == NULL)
   2266 		return (EINVAL);
   2267 	tail++;
   2268 	if (strncmp(oldname, newname, tail - newname) != 0)
   2269 		return (EXDEV);
   2270 
   2271 	if (recursive) {
   2272 		err = dsl_recursive_rename(oldname, newname);
   2273 	} else {
   2274 		err = dsl_dataset_hold(oldname, FTAG, &ds);
   2275 		if (err)
   2276 			return (err);
   2277 
   2278 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
   2279 		    dsl_dataset_snapshot_rename_check,
   2280 		    dsl_dataset_snapshot_rename_sync, ds, (char *)tail, 1);
   2281 
   2282 		dsl_dataset_rele(ds, FTAG);
   2283 	}
   2284 
   2285 	return (err);
   2286 }
   2287 
   2288 struct promotenode {
   2289 	list_node_t link;
   2290 	dsl_dataset_t *ds;
   2291 };
   2292 
   2293 struct promotearg {
   2294 	list_t shared_snaps, origin_snaps, clone_snaps;
   2295 	dsl_dataset_t *origin_origin, *origin_head;
   2296 	uint64_t used, comp, uncomp, unique, cloneusedsnap, originusedsnap;
   2297 };
   2298 
   2299 static int snaplist_space(list_t *l, uint64_t mintxg, uint64_t *spacep);
   2300 
   2301 /* ARGSUSED */
   2302 static int
   2303 dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
   2304 {
   2305 	dsl_dataset_t *hds = arg1;
   2306 	struct promotearg *pa = arg2;
   2307 	struct promotenode *snap = list_head(&pa->shared_snaps);
   2308 	dsl_dataset_t *origin_ds = snap->ds;
   2309 	int err;
   2310 
   2311 	/* Check that it is a real clone */
   2312 	if (!dsl_dir_is_clone(hds->ds_dir))
   2313 		return (EINVAL);
   2314 
   2315 	/* Since this is so expensive, don't do the preliminary check */
   2316 	if (!dmu_tx_is_syncing(tx))
   2317 		return (0);
   2318 
   2319 	if (hds->ds_phys->ds_flags & DS_FLAG_NOPROMOTE)
   2320 		return (EXDEV);
   2321 
   2322 	/* compute origin's new unique space */
   2323 	snap = list_tail(&pa->clone_snaps);
   2324 	ASSERT3U(snap->ds->ds_phys->ds_prev_snap_obj, ==, origin_ds->ds_object);
   2325 	err = bplist_space_birthrange(&snap->ds->ds_deadlist,
   2326 	    origin_ds->ds_phys->ds_prev_snap_txg, UINT64_MAX, &pa->unique);
   2327 	if (err)
   2328 		return (err);
   2329 
   2330 	/*
   2331 	 * Walk the snapshots that we are moving
   2332 	 *
   2333 	 * Compute space to transfer.  Consider the incremental changes
   2334 	 * to used for each snapshot:
   2335 	 * (my used) = (prev's used) + (blocks born) - (blocks killed)
   2336 	 * So each snapshot gave birth to:
   2337 	 * (blocks born) = (my used) - (prev's used) + (blocks killed)
   2338 	 * So a sequence would look like:
   2339 	 * (uN - u(N-1) + kN) + ... + (u1 - u0 + k1) + (u0 - 0 + k0)
   2340 	 * Which simplifies to:
   2341 	 * uN + kN + kN-1 + ... + k1 + k0
   2342 	 * Note however, if we stop before we reach the ORIGIN we get:
   2343 	 * uN + kN + kN-1 + ... + kM - uM-1
   2344 	 */
   2345 	pa->used = origin_ds->ds_phys->ds_used_bytes;
   2346 	pa->comp = origin_ds->ds_phys->ds_compressed_bytes;
   2347 	pa->uncomp = origin_ds->ds_phys->ds_uncompressed_bytes;
   2348 	for (snap = list_head(&pa->shared_snaps); snap;
   2349 	    snap = list_next(&pa->shared_snaps, snap)) {
   2350 		uint64_t val, dlused, dlcomp, dluncomp;
   2351 		dsl_dataset_t *ds = snap->ds;
   2352 
   2353 		/* Check that the snapshot name does not conflict */
   2354 		VERIFY(0 == dsl_dataset_get_snapname(ds));
   2355 		err = dsl_dataset_snap_lookup(hds, ds->ds_snapname, &val);
   2356 		if (err == 0)
   2357 			return (EEXIST);
   2358 		if (err != ENOENT)
   2359 			return (err);
   2360 
   2361 		/* The very first snapshot does not have a deadlist */
   2362 		if (ds->ds_phys->ds_prev_snap_obj == 0)
   2363 			continue;
   2364 
   2365 		if (err = bplist_space(&ds->ds_deadlist,
   2366 		    &dlused, &dlcomp, &dluncomp))
   2367 			return (err);
   2368 		pa->used += dlused;
   2369 		pa->comp += dlcomp;
   2370 		pa->uncomp += dluncomp;
   2371 	}
   2372 
   2373 	/*
   2374 	 * If we are a clone of a clone then we never reached ORIGIN,
   2375 	 * so we need to subtract out the clone origin's used space.
   2376 	 */
   2377 	if (pa->origin_origin) {
   2378 		pa->used -= pa->origin_origin->ds_phys->ds_used_bytes;
   2379 		pa->comp -= pa->origin_origin->ds_phys->ds_compressed_bytes;
   2380 		pa->uncomp -= pa->origin_origin->ds_phys->ds_uncompressed_bytes;
   2381 	}
   2382 
   2383 	/* Check that there is enough space here */
   2384 	err = dsl_dir_transfer_possible(origin_ds->ds_dir, hds->ds_dir,
   2385 	    pa->used);
   2386 	if (err)
   2387 		return (err);
   2388 
   2389 	/*
   2390 	 * Compute the amounts of space that will be used by snapshots
   2391 	 * after the promotion (for both origin and clone).  For each,
   2392 	 * it is the amount of space that will be on all of their
   2393 	 * deadlists (that was not born before their new origin).
   2394 	 */
   2395 	if (hds->ds_dir->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN) {
   2396 		uint64_t space;
   2397 
   2398 		/*
   2399 		 * Note, typically this will not be a clone of a clone,
   2400 		 * so snap->ds->ds_origin_txg will be < TXG_INITIAL, so
   2401 		 * these snaplist_space() -> bplist_space_birthrange()
   2402 		 * calls will be fast because they do not have to
   2403 		 * iterate over all bps.
   2404 		 */
   2405 		snap = list_head(&pa->origin_snaps);
   2406 		err = snaplist_space(&pa->shared_snaps,
   2407 		    snap->ds->ds_origin_txg, &pa->cloneusedsnap);
   2408 		if (err)
   2409 			return (err);
   2410 
   2411 		err = snaplist_space(&pa->clone_snaps,
   2412 		    snap->ds->ds_origin_txg, &space);
   2413 		if (err)
   2414 			return (err);
   2415 		pa->cloneusedsnap += space;
   2416 	}
   2417 	if (origin_ds->ds_dir->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN) {
   2418 		err = snaplist_space(&pa->origin_snaps,
   2419 		    origin_ds->ds_phys->ds_creation_txg, &pa->originusedsnap);
   2420 		if (err)
   2421 			return (err);
   2422 	}
   2423 
   2424 	return (0);
   2425 }
   2426 
   2427 static void
   2428 dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
   2429 {
   2430 	dsl_dataset_t *hds = arg1;
   2431 	struct promotearg *pa = arg2;
   2432 	struct promotenode *snap = list_head(&pa->shared_snaps);
   2433 	dsl_dataset_t *origin_ds = snap->ds;
   2434 	dsl_dataset_t *origin_head;
   2435 	dsl_dir_t *dd = hds->ds_dir;
   2436 	dsl_pool_t *dp = hds->ds_dir->dd_pool;
   2437 	dsl_dir_t *odd = NULL;
   2438 	uint64_t oldnext_obj;
   2439 	int64_t delta;
   2440 
   2441 	ASSERT(0 == (hds->ds_phys->ds_flags & DS_FLAG_NOPROMOTE));
   2442 
   2443 	snap = list_head(&pa->origin_snaps);
   2444 	origin_head = snap->ds;
   2445 
   2446 	/*
   2447 	 * We need to explicitly open odd, since origin_ds's dd will be
   2448 	 * changing.
   2449 	 */
   2450 	VERIFY(0 == dsl_dir_open_obj(dp, origin_ds->ds_dir->dd_object,
   2451 	    NULL, FTAG, &odd));
   2452 
   2453 	/* change origin's next snap */
   2454 	dmu_buf_will_dirty(origin_ds->ds_dbuf, tx);
   2455 	oldnext_obj = origin_ds->ds_phys->ds_next_snap_obj;
   2456 	snap = list_tail(&pa->clone_snaps);
   2457 	ASSERT3U(snap->ds->ds_phys->ds_prev_snap_obj, ==, origin_ds->ds_object);
   2458 	origin_ds->ds_phys->ds_next_snap_obj = snap->ds->ds_object;
   2459 
   2460 	/* change the origin's next clone */
   2461 	if (origin_ds->ds_phys->ds_next_clones_obj) {
   2462 		VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
   2463 		    origin_ds->ds_phys->ds_next_clones_obj,
   2464 		    origin_ds->ds_phys->ds_next_snap_obj, tx));
   2465 		VERIFY3U(0, ==, zap_add_int(dp->dp_meta_objset,
   2466 		    origin_ds->ds_phys->ds_next_clones_obj,
   2467 		    oldnext_obj, tx));
   2468 	}
   2469 
   2470 	/* change origin */
   2471 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
   2472 	ASSERT3U(dd->dd_phys->dd_origin_obj, ==, origin_ds->ds_object);
   2473 	dd->dd_phys->dd_origin_obj = odd->dd_phys->dd_origin_obj;
   2474 	hds->ds_origin_txg = origin_head->ds_origin_txg;
   2475 	dmu_buf_will_dirty(odd->dd_dbuf, tx);
   2476 	odd->dd_phys->dd_origin_obj = origin_ds->ds_object;
   2477 	origin_head->ds_origin_txg = origin_ds->ds_phys->ds_creation_txg;
   2478 
   2479 	/* move snapshots to this dir */
   2480 	for (snap = list_head(&pa->shared_snaps); snap;
   2481 	    snap = list_next(&pa->shared_snaps, snap)) {
   2482 		dsl_dataset_t *ds = snap->ds;
   2483 
   2484 		/* unregister props as dsl_dir is changing */
   2485 		if (ds->ds_user_ptr) {
   2486 			ds->ds_user_evict_func(ds, ds->ds_user_ptr);
   2487 			ds->ds_user_ptr = NULL;
   2488 		}
   2489 		/* move snap name entry */
   2490 		VERIFY(0 == dsl_dataset_get_snapname(ds));
   2491 		VERIFY(0 == dsl_dataset_snap_remove(origin_head,
   2492 		    ds->ds_snapname, tx));
   2493 		VERIFY(0 == zap_add(dp->dp_meta_objset,
   2494 		    hds->ds_phys->ds_snapnames_zapobj, ds->ds_snapname,
   2495 		    8, 1, &ds->ds_object, tx));
   2496 		/* change containing dsl_dir */
   2497 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
   2498 		ASSERT3U(ds->ds_phys->ds_dir_obj, ==, odd->dd_object);
   2499 		ds->ds_phys->ds_dir_obj = dd->dd_object;
   2500 		ASSERT3P(ds->ds_dir, ==, odd);
   2501 		dsl_dir_close(ds->ds_dir, ds);
   2502 		VERIFY(0 == dsl_dir_open_obj(dp, dd->dd_object,
   2503 		    NULL, ds, &ds->ds_dir));
   2504 
   2505 		ASSERT3U(dsl_prop_numcb(ds), ==, 0);
   2506 	}
   2507 
   2508 	/*
   2509 	 * Change space accounting.
   2510 	 * Note, pa->*usedsnap and dd_used_breakdown[SNAP] will either
   2511 	 * both be valid, or both be 0 (resulting in delta == 0).  This
   2512 	 * is true for each of {clone,origin} independently.
   2513 	 */
   2514 
   2515 	delta = pa->cloneusedsnap -
   2516 	    dd->dd_phys->dd_used_breakdown[DD_USED_SNAP];
   2517 	ASSERT3S(delta, >=, 0);
   2518 	ASSERT3U(pa->used, >=, delta);
   2519 	dsl_dir_diduse_space(dd, DD_USED_SNAP, delta, 0, 0, tx);
   2520 	dsl_dir_diduse_space(dd, DD_USED_HEAD,
   2521 	    pa->used - delta, pa->comp, pa->uncomp, tx);
   2522 
   2523 	delta = pa->originusedsnap -
   2524 	    odd->dd_phys->dd_used_breakdown[DD_USED_SNAP];
   2525 	ASSERT3S(delta, <=, 0);
   2526 	ASSERT3U(pa->used, >=, -delta);
   2527 	dsl_dir_diduse_space(odd, DD_USED_SNAP, delta, 0, 0, tx);
   2528 	dsl_dir_diduse_space(odd, DD_USED_HEAD,
   2529 	    -pa->used - delta, -pa->comp, -pa->uncomp, tx);
   2530 
   2531 	origin_ds->ds_phys->ds_unique_bytes = pa->unique;
   2532 
   2533 	/* log history record */
   2534 	spa_history_internal_log(LOG_DS_PROMOTE, dd->dd_pool->dp_spa, tx,
   2535 	    cr, "dataset = %llu", hds->ds_object);
   2536 
   2537 	dsl_dir_close(odd, FTAG);
   2538 }
   2539 
   2540 static char *snaplist_tag = "snaplist";
   2541 /*
   2542  * Make a list of dsl_dataset_t's for the snapshots between first_obj
   2543  * (exclusive) and last_obj (inclusive).  The list will be in reverse
   2544  * order (last_obj will be the list_head()).  If first_obj == 0, do all
   2545  * snapshots back to this dataset's origin.
   2546  */
   2547 static int
   2548 snaplist_make(dsl_pool_t *dp, boolean_t own,
   2549     uint64_t first_obj, uint64_t last_obj, list_t *l)
   2550 {
   2551 	uint64_t obj = last_obj;
   2552 
   2553 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock));
   2554 
   2555 	list_create(l, sizeof (struct promotenode),
   2556 	    offsetof(struct promotenode, link));
   2557 
   2558 	while (obj != first_obj) {
   2559 		dsl_dataset_t *ds;
   2560 		struct promotenode *snap;
   2561 		int err;
   2562 
   2563 		if (own) {
   2564 			err = dsl_dataset_own_obj(dp, obj,
   2565 			    0, snaplist_tag, &ds);
   2566 			if (err == 0)
   2567 				dsl_dataset_make_exclusive(ds, snaplist_tag);
   2568 		} else {
   2569 			err = dsl_dataset_hold_obj(dp, obj, snaplist_tag, &ds);
   2570 		}
   2571 		if (err == ENOENT) {
   2572 			/* lost race with snapshot destroy */
   2573 			struct promotenode *last = list_tail(l);
   2574 			ASSERT(obj != last->ds->ds_phys->ds_prev_snap_obj);
   2575 			obj = last->ds->ds_phys->ds_prev_snap_obj;
   2576 			continue;
   2577 		} else if (err) {
   2578 			return (err);
   2579 		}
   2580 
   2581 		if (first_obj == 0)
   2582 			first_obj = ds->ds_dir->dd_phys->dd_origin_obj;
   2583 
   2584 		snap = kmem_alloc(sizeof (struct promotenode), KM_SLEEP);
   2585 		snap->ds = ds;
   2586 		list_insert_tail(l, snap);
   2587 		obj = ds->ds_phys->ds_prev_snap_obj;
   2588 	}
   2589 
   2590 	return (0);
   2591 }
   2592 
   2593 static int
   2594 snaplist_space(list_t *l, uint64_t mintxg, uint64_t *spacep)
   2595 {
   2596 	struct promotenode *snap;
   2597 
   2598 	*spacep = 0;
   2599 	for (snap = list_head(l); snap; snap = list_next(l, snap)) {
   2600 		uint64_t used;
   2601 		int err = bplist_space_birthrange(&snap->ds->ds_deadlist,
   2602 		    mintxg, UINT64_MAX, &used);
   2603 		if (err)
   2604 			return (err);
   2605 		*spacep += used;
   2606 	}
   2607 	return (0);
   2608 }
   2609 
   2610 static void
   2611 snaplist_destroy(list_t *l, boolean_t own)
   2612 {
   2613 	struct promotenode *snap;
   2614 
   2615 	if (!l || !list_link_active(&l->list_head))
   2616 		return;
   2617 
   2618 	while ((snap = list_tail(l)) != NULL) {
   2619 		list_remove(l, snap);
   2620 		if (own)
   2621 			dsl_dataset_disown(snap->ds, snaplist_tag);
   2622 		else
   2623 			dsl_dataset_rele(snap->ds, snaplist_tag);
   2624 		kmem_free(snap, sizeof (struct promotenode));
   2625 	}
   2626 	list_destroy(l);
   2627 }
   2628 
   2629 /*
   2630  * Promote a clone.  Nomenclature note:
   2631  * "clone" or "cds": the original clone which is being promoted
   2632  * "origin" or "ods": the snapshot which is originally clone's origin
   2633  * "origin head" or "ohds": the dataset which is the head
   2634  * (filesystem/volume) for the origin
   2635  * "origin origin": the origin of the origin's filesystem (typically
   2636  * NULL, indicating that the clone is not a clone of a clone).
   2637  */
   2638 int
   2639 dsl_dataset_promote(const char *name)
   2640 {
   2641 	dsl_dataset_t *ds;
   2642 	dsl_dir_t *dd;
   2643 	dsl_pool_t *dp;
   2644 	dmu_object_info_t doi;
   2645 	struct promotearg pa = { 0 };
   2646 	struct promotenode *snap;
   2647 	int err;
   2648 
   2649 	err = dsl_dataset_hold(name, FTAG, &ds);
   2650 	if (err)
   2651 		return (err);
   2652 	dd = ds->ds_dir;
   2653 	dp = dd->dd_pool;
   2654 
   2655 	err = dmu_object_info(dp->dp_meta_objset,
   2656 	    ds->ds_phys->ds_snapnames_zapobj, &doi);
   2657 	if (err) {
   2658 		dsl_dataset_rele(ds, FTAG);
   2659 		return (err);
   2660 	}
   2661 
   2662 	if (dsl_dataset_is_snapshot(ds) || dd->dd_phys->dd_origin_obj == 0) {
   2663 		dsl_dataset_rele(ds, FTAG);
   2664 		return (EINVAL);
   2665 	}
   2666 
   2667 	/*
   2668 	 * We are going to inherit all the snapshots taken before our
   2669 	 * origin (i.e., our new origin will be our parent's origin).
   2670 	 * Take ownership of them so that we can rename them into our
   2671 	 * namespace.
   2672 	 */
   2673 	rw_enter(&dp->dp_config_rwlock, RW_READER);
   2674 
   2675 	err = snaplist_make(dp, B_TRUE, 0, dd->dd_phys->dd_origin_obj,
   2676 	    &pa.shared_snaps);
   2677 	if (err != 0)
   2678 		goto out;
   2679 
   2680 	err = snaplist_make(dp, B_FALSE, 0, ds->ds_object, &pa.clone_snaps);
   2681 	if (err != 0)
   2682 		goto out;
   2683 
   2684 	snap = list_head(&pa.shared_snaps);
   2685 	ASSERT3U(snap->ds->ds_object, ==, dd->dd_phys->dd_origin_obj);
   2686 	err = snaplist_make(dp, B_FALSE, dd->dd_phys->dd_origin_obj,
   2687 	    snap->ds->ds_dir->dd_phys->dd_head_dataset_obj, &pa.origin_snaps);
   2688 	if (err != 0)
   2689 		goto out;
   2690 
   2691 	if (dsl_dir_is_clone(snap->ds->ds_dir)) {
   2692 		err = dsl_dataset_own_obj(dp,
   2693 		    snap->ds->ds_dir->dd_phys->dd_origin_obj,
   2694 		    0, FTAG, &pa.origin_origin);
   2695 		if (err != 0)
   2696 			goto out;
   2697 	}
   2698 
   2699 out:
   2700 	rw_exit(&dp->dp_config_rwlock);
   2701 
   2702 	/*
   2703 	 * Add in 128x the snapnames zapobj size, since we will be moving
   2704 	 * a bunch of snapnames to the promoted ds, and dirtying their
   2705 	 * bonus buffers.
   2706 	 */
   2707 	if (err == 0) {
   2708 		err = dsl_sync_task_do(dp, dsl_dataset_promote_check,
   2709 		    dsl_dataset_promote_sync, ds, &pa,
   2710 		    2 + 2 * doi.doi_physical_blks);
   2711 	}
   2712 
   2713 	snaplist_destroy(&pa.shared_snaps, B_TRUE);
   2714 	snaplist_destroy(&pa.clone_snaps, B_FALSE);
   2715 	snaplist_destroy(&pa.origin_snaps, B_FALSE);
   2716 	if (pa.origin_origin)
   2717 		dsl_dataset_disown(pa.origin_origin, FTAG);
   2718 	dsl_dataset_rele(ds, FTAG);
   2719 	return (err);
   2720 }
   2721 
   2722 struct cloneswaparg {
   2723 	dsl_dataset_t *cds; /* clone dataset */
   2724 	dsl_dataset_t *ohds; /* origin's head dataset */
   2725 	boolean_t force;
   2726 	int64_t unused_refres_delta; /* change in unconsumed refreservation */
   2727 };
   2728 
   2729 /* ARGSUSED */
   2730 static int
   2731 dsl_dataset_clone_swap_check(void *arg1, void *arg2, dmu_tx_t *tx)
   2732 {
   2733 	struct cloneswaparg *csa = arg1;
   2734 
   2735 	/* they should both be heads */
   2736 	if (dsl_dataset_is_snapshot(csa->cds) ||
   2737 	    dsl_dataset_is_snapshot(csa->ohds))
   2738 		return (EINVAL);
   2739 
   2740 	/* the branch point should be just before them */
   2741 	if (csa->cds->ds_prev != csa->ohds->ds_prev)
   2742 		return (EINVAL);
   2743 
   2744 	/* cds should be the clone */
   2745 	if (csa->cds->ds_prev->ds_phys->ds_next_snap_obj !=
   2746 	    csa->ohds->ds_object)
   2747 		return (EINVAL);
   2748 
   2749 	/* the clone should be a child of the origin */
   2750 	if (csa->cds->ds_dir->dd_parent != csa->ohds->ds_dir)
   2751 		return (EINVAL);
   2752 
   2753 	/* ohds shouldn't be modified unless 'force' */
   2754 	if (!csa->force && dsl_dataset_modified_since_lastsnap(csa->ohds))
   2755 		return (ETXTBSY);
   2756 
   2757 	/* adjust amount of any unconsumed refreservation */
   2758 	csa->unused_refres_delta =
   2759 	    (int64_t)MIN(csa->ohds->ds_reserved,
   2760 	    csa->ohds->ds_phys->ds_unique_bytes) -
   2761 	    (int64_t)MIN(csa->ohds->ds_reserved,
   2762 	    csa->cds->ds_phys->ds_unique_bytes);
   2763 
   2764 	if (csa->unused_refres_delta > 0 &&
   2765 	    csa->unused_refres_delta >
   2766 	    dsl_dir_space_available(csa->ohds->ds_dir, NULL, 0, TRUE))
   2767 		return (ENOSPC);
   2768 
   2769 	return (0);
   2770 }
   2771 
   2772 /* ARGSUSED */
   2773 static void
   2774 dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
   2775 {
   2776 	struct cloneswaparg *csa = arg1;
   2777 	dsl_pool_t *dp = csa->cds->ds_dir->dd_pool;
   2778 
   2779 	ASSERT(csa->cds->ds_reserved == 0);
   2780 	ASSERT(csa->cds->ds_quota == csa->ohds->ds_quota);
   2781 
   2782 	dmu_buf_will_dirty(csa->cds->ds_dbuf, tx);
   2783 	dmu_buf_will_dirty(csa->ohds->ds_dbuf, tx);
   2784 	dmu_buf_will_dirty(csa->cds->ds_prev->ds_dbuf, tx);
   2785 
   2786 	if (csa->cds->ds_user_ptr != NULL) {
   2787 		csa->cds->ds_user_evict_func(csa->cds, csa->cds->ds_user_ptr);
   2788 		csa->cds->ds_user_ptr = NULL;
   2789 	}
   2790 
   2791 	if (csa->ohds->ds_user_ptr != NULL) {
   2792 		csa->ohds->ds_user_evict_func(csa->ohds,
   2793 		    csa->ohds->ds_user_ptr);
   2794 		csa->ohds->ds_user_ptr = NULL;
   2795 	}
   2796 
   2797 	/* reset origin's unique bytes */
   2798 	VERIFY(0 == bplist_space_birthrange(&csa->cds->ds_deadlist,
   2799 	    csa->cds->ds_prev->ds_phys->ds_prev_snap_txg, UINT64_MAX,
   2800 	    &csa->cds->ds_prev->ds_phys->ds_unique_bytes));
   2801 
   2802 	/* swap blkptrs */
   2803 	{
   2804 		blkptr_t tmp;
   2805 		tmp = csa->ohds->ds_phys->ds_bp;
   2806 		csa->ohds->ds_phys->ds_bp = csa->cds->ds_phys->ds_bp;
   2807 		csa->cds->ds_phys->ds_bp = tmp;
   2808 	}
   2809 
   2810 	/* set dd_*_bytes */
   2811 	{
   2812 		int64_t dused, dcomp, duncomp;
   2813 		uint64_t cdl_used, cdl_comp, cdl_uncomp;
   2814 		uint64_t odl_used, odl_comp, odl_uncomp;
   2815 
   2816 		ASSERT3U(csa->cds->ds_dir->dd_phys->
   2817 		    dd_used_breakdown[DD_USED_SNAP], ==, 0);
   2818 
   2819 		VERIFY(0 == bplist_space(&csa->cds->ds_deadlist, &cdl_used,
   2820 		    &cdl_comp, &cdl_uncomp));
   2821 		VERIFY(0 == bplist_space(&csa->ohds->ds_deadlist, &odl_used,
   2822 		    &odl_comp, &odl_uncomp));
   2823 
   2824 		dused = csa->cds->ds_phys->ds_used_bytes + cdl_used -
   2825 		    (csa->ohds->ds_phys->ds_used_bytes + odl_used);
   2826 		dcomp = csa->cds->ds_phys->ds_compressed_bytes + cdl_comp -
   2827 		    (csa->ohds->ds_phys->ds_compressed_bytes + odl_comp);
   2828 		duncomp = csa->cds->ds_phys->ds_uncompressed_bytes +
   2829 		    cdl_uncomp -
   2830 		    (csa->ohds->ds_phys->ds_uncompressed_bytes + odl_uncomp);
   2831 
   2832 		dsl_dir_diduse_space(csa->ohds->ds_dir, DD_USED_HEAD,
   2833 		    dused, dcomp, duncomp, tx);
   2834 		dsl_dir_diduse_space(csa->cds->ds_dir, DD_USED_HEAD,
   2835 		    -dused, -dcomp, -duncomp, tx);
   2836 
   2837 		/*
   2838 		 * The difference in the space used by snapshots is the
   2839 		 * difference in snapshot space due to the head's
   2840 		 * deadlist (since that's the only thing that's
   2841 		 * changing that affects the snapused).
   2842 		 */
   2843 		VERIFY(0 == bplist_space_birthrange(&csa->cds->ds_deadlist,
   2844 		    csa->ohds->ds_origin_txg, UINT64_MAX, &cdl_used));
   2845 		VERIFY(0 == bplist_space_birthrange(&csa->ohds->ds_deadlist,
   2846 		    csa->ohds->ds_origin_txg, UINT64_MAX, &odl_used));
   2847 		dsl_dir_transfer_space(csa->ohds->ds_dir, cdl_used - odl_used,
   2848 		    DD_USED_HEAD, DD_USED_SNAP, tx);
   2849 	}
   2850 
   2851 #define	SWITCH64(x, y) \
   2852 	{ \
   2853 		uint64_t __tmp = (x); \
   2854 		(x) = (y); \
   2855 		(y) = __tmp; \
   2856 	}
   2857 
   2858 	/* swap ds_*_bytes */
   2859 	SWITCH64(csa->ohds->ds_phys->ds_used_bytes,
   2860 	    csa->cds->ds_phys->ds_used_bytes);
   2861 	SWITCH64(csa->ohds->ds_phys->ds_compressed_bytes,
   2862 	    csa->cds->ds_phys->ds_compressed_bytes);
   2863 	SWITCH64(csa->ohds->ds_phys->ds_uncompressed_bytes,
   2864 	    csa->cds->ds_phys->ds_uncompressed_bytes);
   2865 	SWITCH64(csa->ohds->ds_phys->ds_unique_bytes,
   2866 	    csa->cds->ds_phys->ds_unique_bytes);
   2867 
   2868 	/* apply any parent delta for change in unconsumed refreservation */
   2869 	dsl_dir_diduse_space(csa->ohds->ds_dir, DD_USED_REFRSRV,
   2870 	    csa->unused_refres_delta, 0, 0, tx);
   2871 
   2872 	/* swap deadlists */
   2873 	bplist_close(&csa->cds->ds_deadlist);
   2874 	bplist_close(&csa->ohds->ds_deadlist);
   2875 	SWITCH64(csa->ohds->ds_phys->ds_deadlist_obj,
   2876 	    csa->cds->ds_phys->ds_deadlist_obj);
   2877 	VERIFY(0 == bplist_open(&csa->cds->ds_deadlist, dp->dp_meta_objset,
   2878 	    csa->cds->ds_phys->ds_deadlist_obj));
   2879 	VERIFY(0 == bplist_open(&csa->ohds->ds_deadlist, dp->dp_meta_objset,
   2880 	    csa->ohds->ds_phys->ds_deadlist_obj));
   2881 
   2882 	dsl_pool_ds_clone_swapped(csa->ohds, csa->cds, tx);
   2883 }
   2884 
   2885 /*
   2886  * Swap 'clone' with its origin head file system.  Used at the end
   2887  * of "online recv" to swizzle the file system to the new version.
   2888  */
   2889 int
   2890 dsl_dataset_clone_swap(dsl_dataset_t *clone, dsl_dataset_t *origin_head,
   2891     boolean_t force)
   2892 {
   2893 	struct cloneswaparg csa;
   2894 	int error;
   2895 
   2896 	ASSERT(clone->ds_owner);
   2897 	ASSERT(origin_head->ds_owner);
   2898 retry:
   2899 	/* Need exclusive access for the swap */
   2900 	rw_enter(&clone->ds_rwlock, RW_WRITER);
   2901 	if (!rw_tryenter(&origin_head->ds_rwlock, RW_WRITER)) {
   2902 		rw_exit(&clone->ds_rwlock);
   2903 		rw_enter(&origin_head->ds_rwlock, RW_WRITER);
   2904 		if (!rw_tryenter(&clone->ds_rwlock, RW_WRITER)) {
   2905 			rw_exit(&origin_head->ds_rwlock);
   2906 			goto retry;
   2907 		}
   2908 	}
   2909 	csa.cds = clone;
   2910 	csa.ohds = origin_head;
   2911 	csa.force = force;
   2912 	error = dsl_sync_task_do(clone->ds_dir->dd_pool,
   2913 	    dsl_dataset_clone_swap_check,
   2914 	    dsl_dataset_clone_swap_sync, &csa, NULL, 9);
   2915 	return (error);
   2916 }
   2917 
   2918 /*
   2919  * Given a pool name and a dataset object number in that pool,
   2920  * return the name of that dataset.
   2921  */
   2922 int
   2923 dsl_dsobj_to_dsname(char *pname, uint64_t obj, char *buf)
   2924 {
   2925 	spa_t *spa;
   2926 	dsl_pool_t *dp;
   2927 	dsl_dataset_t *ds;
   2928 	int error;
   2929 
   2930 	if ((error = spa_open(pname, &spa, FTAG)) != 0)
   2931 		return (error);
   2932 	dp = spa_get_dsl(spa);
   2933 	rw_enter(&dp->dp_config_rwlock, RW_READER);
   2934 	if ((error = dsl_dataset_hold_obj(dp, obj, FTAG, &ds)) == 0) {
   2935 		dsl_dataset_name(ds, buf);
   2936 		dsl_dataset_rele(ds, FTAG);
   2937 	}
   2938 	rw_exit(&dp->dp_config_rwlock);
   2939 	spa_close(spa, FTAG);
   2940 
   2941 	return (error);
   2942 }
   2943 
   2944 int
   2945 dsl_dataset_check_quota(dsl_dataset_t *ds, boolean_t check_quota,
   2946     uint64_t asize, uint64_t inflight, uint64_t *used, uint64_t *ref_rsrv)
   2947 {
   2948 	int error = 0;
   2949 
   2950 	ASSERT3S(asize, >, 0);
   2951 
   2952 	/*
   2953 	 * *ref_rsrv is the portion of asize that will come from any
   2954 	 * unconsumed refreservation space.
   2955 	 */
   2956 	*ref_rsrv = 0;
   2957 
   2958 	mutex_enter(&ds->ds_lock);
   2959 	/*
   2960 	 * Make a space adjustment for reserved bytes.
   2961 	 */
   2962 	if (ds->ds_reserved > ds->ds_phys->ds_unique_bytes) {
   2963 		ASSERT3U(*used, >=,
   2964 		    ds->ds_reserved - ds->ds_phys->ds_unique_bytes);
   2965 		*used -= (ds->ds_reserved - ds->ds_phys->ds_unique_bytes);
   2966 		*ref_rsrv =
   2967 		    asize - MIN(asize, parent_delta(ds, asize + inflight));
   2968 	}
   2969 
   2970 	if (!check_quota || ds->ds_quota == 0) {
   2971 		mutex_exit(&ds->ds_lock);
   2972 		return (0);
   2973 	}
   2974 	/*
   2975 	 * If they are requesting more space, and our current estimate
   2976 	 * is over quota, they get to try again unless the actual
   2977 	 * on-disk is over quota and there are no pending changes (which
   2978 	 * may free up space for us).
   2979 	 */
   2980 	if (ds->ds_phys->ds_used_bytes + inflight >= ds->ds_quota) {
   2981 		if (inflight > 0 || ds->ds_phys->ds_used_bytes < ds->ds_quota)
   2982 			error = ERESTART;
   2983 		else
   2984 			error = EDQUOT;
   2985 	}
   2986 	mutex_exit(&ds->ds_lock);
   2987 
   2988 	return (error);
   2989 }
   2990 
   2991 /* ARGSUSED */
   2992 static int
   2993 dsl_dataset_set_quota_check(void *arg1, void *arg2, dmu_tx_t *tx)
   2994 {
   2995 	dsl_dataset_t *ds = arg1;
   2996 	uint64_t *quotap = arg2;
   2997 	uint64_t new_quota = *quotap;
   2998 
   2999 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) < SPA_VERSION_REFQUOTA)
   3000 		return (ENOTSUP);
   3001 
   3002 	if (new_quota == 0)
   3003 		return (0);
   3004 
   3005 	if (new_quota < ds->ds_phys->ds_used_bytes ||
   3006 	    new_quota < ds->ds_reserved)
   3007 		return (ENOSPC);
   3008 
   3009 	return (0);
   3010 }
   3011 
   3012 /* ARGSUSED */
   3013 void
   3014 dsl_dataset_set_quota_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
   3015 {
   3016 	dsl_dataset_t *ds = arg1;
   3017 	uint64_t *quotap = arg2;
   3018 	uint64_t new_quota = *quotap;
   3019 
   3020 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
   3021 
   3022 	ds->ds_quota = new_quota;
   3023 
   3024 	dsl_prop_set_uint64_sync(ds->ds_dir, "refquota", new_quota, cr, tx);
   3025 
   3026 	spa_history_internal_log(LOG_DS_REFQUOTA, ds->ds_dir->dd_pool->dp_spa,
   3027 	    tx, cr, "%lld dataset = %llu ",
   3028 	    (longlong_t)new_quota, ds->ds_object);
   3029 }
   3030 
   3031 int
   3032 dsl_dataset_set_quota(const char *dsname, uint64_t quota)
   3033 {
   3034 	dsl_dataset_t *ds;
   3035 	int err;
   3036 
   3037 	err = dsl_dataset_hold(dsname, FTAG, &ds);
   3038 	if (err)
   3039 		return (err);
   3040 
   3041 	if (quota != ds->ds_quota) {
   3042 		/*
   3043 		 * If someone removes a file, then tries to set the quota, we
   3044 		 * want to make sure the file freeing takes effect.
   3045 		 */
   3046 		txg_wait_open(ds->ds_dir->dd_pool, 0);
   3047 
   3048 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
   3049 		    dsl_dataset_set_quota_check, dsl_dataset_set_quota_sync,
   3050 		    ds, &quota, 0);
   3051 	}
   3052 	dsl_dataset_rele(ds, FTAG);
   3053 	return (err);
   3054 }
   3055 
   3056 static int
   3057 dsl_dataset_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
   3058 {
   3059 	dsl_dataset_t *ds = arg1;
   3060 	uint64_t *reservationp = arg2;
   3061 	uint64_t new_reservation = *reservationp;
   3062 	uint64_t unique;
   3063 
   3064 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) <
   3065 	    SPA_VERSION_REFRESERVATION)
   3066 		return (ENOTSUP);
   3067 
   3068 	if (dsl_dataset_is_snapshot(ds))
   3069 		return (EINVAL);
   3070 
   3071 	/*
   3072 	 * If we are doing the preliminary check in open context, the
   3073 	 * space estimates may be inaccurate.
   3074 	 */
   3075 	if (!dmu_tx_is_syncing(tx))
   3076 		return (0);
   3077 
   3078 	mutex_enter(&ds->ds_lock);
   3079 	unique = dsl_dataset_unique(ds);
   3080 	mutex_exit(&ds->ds_lock);
   3081 
   3082 	if (MAX(unique, new_reservation) > MAX(unique, ds->ds_reserved)) {
   3083 		uint64_t delta = MAX(unique, new_reservation) -
   3084 		    MAX(unique, ds->ds_reserved);
   3085 
   3086 		if (delta > dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE))
   3087 			return (ENOSPC);
   3088 		if (ds->ds_quota > 0 &&
   3089 		    new_reservation > ds->ds_quota)
   3090 			return (ENOSPC);
   3091 	}
   3092 
   3093 	return (0);
   3094 }
   3095 
   3096 /* ARGSUSED */
   3097 static void
   3098 dsl_dataset_set_reservation_sync(void *arg1, void *arg2, cred_t *cr,
   3099     dmu_tx_t *tx)
   3100 {
   3101 	dsl_dataset_t *ds = arg1;
   3102 	uint64_t *reservationp = arg2;
   3103 	uint64_t new_reservation = *reservationp;
   3104 	uint64_t unique;
   3105 	int64_t delta;
   3106 
   3107 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
   3108 
   3109 	mutex_enter(&ds->ds_dir->dd_lock);
   3110 	mutex_enter(&ds->ds_lock);
   3111 	unique = dsl_dataset_unique(ds);
   3112 	delta = MAX(0, (int64_t)(new_reservation - unique)) -
   3113 	    MAX(0, (int64_t)(ds->ds_reserved - unique));
   3114 	ds->ds_reserved = new_reservation;
   3115 	mutex_exit(&ds->ds_lock);
   3116 
   3117 	dsl_dir_diduse_space(ds->ds_dir, DD_USED_REFRSRV, delta, 0, 0, tx);
   3118 	mutex_exit(&ds->ds_dir->dd_lock);
   3119 	dsl_prop_set_uint64_sync(ds->ds_dir, "refreservation",
   3120 	    new_reservation, cr, tx);
   3121 
   3122 	spa_history_internal_log(LOG_DS_REFRESERV,
   3123 	    ds->ds_dir->dd_pool->dp_spa, tx, cr, "%lld dataset = %llu",
   3124 	    (longlong_t)new_reservation, ds->ds_object);
   3125 }
   3126 
   3127 int
   3128 dsl_dataset_set_reservation(const char *dsname, uint64_t reservation)
   3129 {
   3130 	dsl_dataset_t *ds;
   3131 	int err;
   3132 
   3133 	err = dsl_dataset_hold(dsname, FTAG, &ds);
   3134 	if (err)
   3135 		return (err);
   3136 
   3137 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
   3138 	    dsl_dataset_set_reservation_check,
   3139 	    dsl_dataset_set_reservation_sync, ds, &reservation, 0);
   3140 	dsl_dataset_rele(ds, FTAG);
   3141 	return (err);
   3142 }
   3143