xref: /titanic_50/usr/src/uts/common/fs/zfs/dsl_dataset.c (revision 5b7f77ad52bf657ba49d64d16f527e958d0fb820)
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 2007 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #pragma ident	"%Z%%M%	%I%	%E% SMI"
27 
28 #include <sys/dmu_objset.h>
29 #include <sys/dsl_dataset.h>
30 #include <sys/dsl_dir.h>
31 #include <sys/dsl_prop.h>
32 #include <sys/dsl_synctask.h>
33 #include <sys/dmu_traverse.h>
34 #include <sys/dmu_tx.h>
35 #include <sys/arc.h>
36 #include <sys/zio.h>
37 #include <sys/zap.h>
38 #include <sys/unique.h>
39 #include <sys/zfs_context.h>
40 #include <sys/zfs_ioctl.h>
41 #include <sys/spa.h>
42 #include <sys/sunddi.h>
43 
44 static dsl_checkfunc_t dsl_dataset_destroy_begin_check;
45 static dsl_syncfunc_t dsl_dataset_destroy_begin_sync;
46 static dsl_checkfunc_t dsl_dataset_rollback_check;
47 static dsl_syncfunc_t dsl_dataset_rollback_sync;
48 static dsl_syncfunc_t dsl_dataset_set_reservation_sync;
49 
50 #define	DS_REF_MAX	(1ULL << 62)
51 
52 #define	DSL_DEADLIST_BLOCKSIZE	SPA_MAXBLOCKSIZE
53 
54 /*
55  * We use weighted reference counts to express the various forms of exclusion
56  * between different open modes.  A STANDARD open is 1 point, an EXCLUSIVE open
57  * is DS_REF_MAX, and a PRIMARY open is little more than half of an EXCLUSIVE.
58  * This makes the exclusion logic simple: the total refcnt for all opens cannot
59  * exceed DS_REF_MAX.  For example, EXCLUSIVE opens are exclusive because their
60  * weight (DS_REF_MAX) consumes the entire refcnt space.  PRIMARY opens consume
61  * just over half of the refcnt space, so there can't be more than one, but it
62  * can peacefully coexist with any number of STANDARD opens.
63  */
64 static uint64_t ds_refcnt_weight[DS_MODE_LEVELS] = {
65 	0,			/* DS_MODE_NONE - invalid		*/
66 	1,			/* DS_MODE_STANDARD - unlimited number	*/
67 	(DS_REF_MAX >> 1) + 1,	/* DS_MODE_PRIMARY - only one of these	*/
68 	DS_REF_MAX		/* DS_MODE_EXCLUSIVE - no other opens	*/
69 };
70 
71 /*
72  * Figure out how much of this delta should be propogated to the dsl_dir
73  * layer.  If there's a refreservation, that space has already been
74  * partially accounted for in our ancestors.
75  */
76 static int64_t
77 parent_delta(dsl_dataset_t *ds, int64_t delta)
78 {
79 	uint64_t old_bytes, new_bytes;
80 
81 	if (ds->ds_reserved == 0)
82 		return (delta);
83 
84 	old_bytes = MAX(ds->ds_phys->ds_unique_bytes, ds->ds_reserved);
85 	new_bytes = MAX(ds->ds_phys->ds_unique_bytes + delta, ds->ds_reserved);
86 
87 	ASSERT3U(ABS((int64_t)(new_bytes - old_bytes)), <=, ABS(delta));
88 	return (new_bytes - old_bytes);
89 }
90 
91 void
92 dsl_dataset_block_born(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
93 {
94 	int used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
95 	int compressed = BP_GET_PSIZE(bp);
96 	int uncompressed = BP_GET_UCSIZE(bp);
97 	int64_t delta;
98 
99 	dprintf_bp(bp, "born, ds=%p\n", ds);
100 
101 	ASSERT(dmu_tx_is_syncing(tx));
102 	/* It could have been compressed away to nothing */
103 	if (BP_IS_HOLE(bp))
104 		return;
105 	ASSERT(BP_GET_TYPE(bp) != DMU_OT_NONE);
106 	ASSERT3U(BP_GET_TYPE(bp), <, DMU_OT_NUMTYPES);
107 	if (ds == NULL) {
108 		/*
109 		 * Account for the meta-objset space in its placeholder
110 		 * dsl_dir.
111 		 */
112 		ASSERT3U(compressed, ==, uncompressed); /* it's all metadata */
113 		dsl_dir_diduse_space(tx->tx_pool->dp_mos_dir,
114 		    used, compressed, uncompressed, tx);
115 		dsl_dir_dirty(tx->tx_pool->dp_mos_dir, tx);
116 		return;
117 	}
118 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
119 	mutex_enter(&ds->ds_lock);
120 	delta = parent_delta(ds, used);
121 	ds->ds_phys->ds_used_bytes += used;
122 	ds->ds_phys->ds_compressed_bytes += compressed;
123 	ds->ds_phys->ds_uncompressed_bytes += uncompressed;
124 	ds->ds_phys->ds_unique_bytes += used;
125 	mutex_exit(&ds->ds_lock);
126 	dsl_dir_diduse_space(ds->ds_dir, delta, compressed, uncompressed, tx);
127 }
128 
129 void
130 dsl_dataset_block_kill(dsl_dataset_t *ds, blkptr_t *bp, zio_t *pio,
131     dmu_tx_t *tx)
132 {
133 	int used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
134 	int compressed = BP_GET_PSIZE(bp);
135 	int uncompressed = BP_GET_UCSIZE(bp);
136 
137 	ASSERT(dmu_tx_is_syncing(tx));
138 	/* No block pointer => nothing to free */
139 	if (BP_IS_HOLE(bp))
140 		return;
141 
142 	ASSERT(used > 0);
143 	if (ds == NULL) {
144 		int err;
145 		/*
146 		 * Account for the meta-objset space in its placeholder
147 		 * dataset.
148 		 */
149 		err = arc_free(pio, tx->tx_pool->dp_spa,
150 		    tx->tx_txg, bp, NULL, NULL, pio ? ARC_NOWAIT: ARC_WAIT);
151 		ASSERT(err == 0);
152 
153 		dsl_dir_diduse_space(tx->tx_pool->dp_mos_dir,
154 		    -used, -compressed, -uncompressed, tx);
155 		dsl_dir_dirty(tx->tx_pool->dp_mos_dir, tx);
156 		return;
157 	}
158 	ASSERT3P(tx->tx_pool, ==, ds->ds_dir->dd_pool);
159 
160 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
161 
162 	if (bp->blk_birth > ds->ds_phys->ds_prev_snap_txg) {
163 		int err;
164 		int64_t delta;
165 
166 		dprintf_bp(bp, "freeing: %s", "");
167 		err = arc_free(pio, tx->tx_pool->dp_spa,
168 		    tx->tx_txg, bp, NULL, NULL, pio ? ARC_NOWAIT: ARC_WAIT);
169 		ASSERT(err == 0);
170 
171 		mutex_enter(&ds->ds_lock);
172 		ASSERT(ds->ds_phys->ds_unique_bytes >= used ||
173 		    !DS_UNIQUE_IS_ACCURATE(ds));
174 		delta = parent_delta(ds, -used);
175 		ds->ds_phys->ds_unique_bytes -= used;
176 		mutex_exit(&ds->ds_lock);
177 		dsl_dir_diduse_space(ds->ds_dir,
178 		    delta, -compressed, -uncompressed, tx);
179 	} else {
180 		dprintf_bp(bp, "putting on dead list: %s", "");
181 		VERIFY(0 == bplist_enqueue(&ds->ds_deadlist, bp, tx));
182 		ASSERT3U(ds->ds_prev->ds_object, ==,
183 		    ds->ds_phys->ds_prev_snap_obj);
184 		ASSERT(ds->ds_prev->ds_phys->ds_num_children > 0);
185 		/* if (bp->blk_birth > prev prev snap txg) prev unique += bs */
186 		if (ds->ds_prev->ds_phys->ds_next_snap_obj ==
187 		    ds->ds_object && bp->blk_birth >
188 		    ds->ds_prev->ds_phys->ds_prev_snap_txg) {
189 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
190 			mutex_enter(&ds->ds_prev->ds_lock);
191 			ds->ds_prev->ds_phys->ds_unique_bytes += used;
192 			mutex_exit(&ds->ds_prev->ds_lock);
193 		}
194 	}
195 	mutex_enter(&ds->ds_lock);
196 	ASSERT3U(ds->ds_phys->ds_used_bytes, >=, used);
197 	ds->ds_phys->ds_used_bytes -= used;
198 	ASSERT3U(ds->ds_phys->ds_compressed_bytes, >=, compressed);
199 	ds->ds_phys->ds_compressed_bytes -= compressed;
200 	ASSERT3U(ds->ds_phys->ds_uncompressed_bytes, >=, uncompressed);
201 	ds->ds_phys->ds_uncompressed_bytes -= uncompressed;
202 	mutex_exit(&ds->ds_lock);
203 }
204 
205 uint64_t
206 dsl_dataset_prev_snap_txg(dsl_dataset_t *ds)
207 {
208 	uint64_t trysnap = 0;
209 
210 	if (ds == NULL)
211 		return (0);
212 	/*
213 	 * The snapshot creation could fail, but that would cause an
214 	 * incorrect FALSE return, which would only result in an
215 	 * overestimation of the amount of space that an operation would
216 	 * consume, which is OK.
217 	 *
218 	 * There's also a small window where we could miss a pending
219 	 * snapshot, because we could set the sync task in the quiescing
220 	 * phase.  So this should only be used as a guess.
221 	 */
222 	if (ds->ds_trysnap_txg >
223 	    spa_last_synced_txg(ds->ds_dir->dd_pool->dp_spa))
224 		trysnap = ds->ds_trysnap_txg;
225 	return (MAX(ds->ds_phys->ds_prev_snap_txg, trysnap));
226 }
227 
228 int
229 dsl_dataset_block_freeable(dsl_dataset_t *ds, uint64_t blk_birth)
230 {
231 	return (blk_birth > dsl_dataset_prev_snap_txg(ds));
232 }
233 
234 /* ARGSUSED */
235 static void
236 dsl_dataset_evict(dmu_buf_t *db, void *dsv)
237 {
238 	dsl_dataset_t *ds = dsv;
239 
240 	/* open_refcount == DS_REF_MAX when deleting */
241 	ASSERT(ds->ds_open_refcount == 0 ||
242 	    ds->ds_open_refcount == DS_REF_MAX);
243 
244 	dprintf_ds(ds, "evicting %s\n", "");
245 
246 	unique_remove(ds->ds_fsid_guid);
247 
248 	if (ds->ds_user_ptr != NULL)
249 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
250 
251 	if (ds->ds_prev) {
252 		dsl_dataset_close(ds->ds_prev, DS_MODE_NONE, ds);
253 		ds->ds_prev = NULL;
254 	}
255 
256 	bplist_close(&ds->ds_deadlist);
257 	dsl_dir_close(ds->ds_dir, ds);
258 
259 	ASSERT(!list_link_active(&ds->ds_synced_link));
260 
261 	mutex_destroy(&ds->ds_lock);
262 	mutex_destroy(&ds->ds_opening_lock);
263 	mutex_destroy(&ds->ds_deadlist.bpl_lock);
264 
265 	kmem_free(ds, sizeof (dsl_dataset_t));
266 }
267 
268 static int
269 dsl_dataset_get_snapname(dsl_dataset_t *ds)
270 {
271 	dsl_dataset_phys_t *headphys;
272 	int err;
273 	dmu_buf_t *headdbuf;
274 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
275 	objset_t *mos = dp->dp_meta_objset;
276 
277 	if (ds->ds_snapname[0])
278 		return (0);
279 	if (ds->ds_phys->ds_next_snap_obj == 0)
280 		return (0);
281 
282 	err = dmu_bonus_hold(mos, ds->ds_dir->dd_phys->dd_head_dataset_obj,
283 	    FTAG, &headdbuf);
284 	if (err)
285 		return (err);
286 	headphys = headdbuf->db_data;
287 	err = zap_value_search(dp->dp_meta_objset,
288 	    headphys->ds_snapnames_zapobj, ds->ds_object, 0, ds->ds_snapname);
289 	dmu_buf_rele(headdbuf, FTAG);
290 	return (err);
291 }
292 
293 int
294 dsl_dataset_open_obj(dsl_pool_t *dp, uint64_t dsobj, const char *snapname,
295     int mode, void *tag, dsl_dataset_t **dsp)
296 {
297 	uint64_t weight = ds_refcnt_weight[DS_MODE_LEVEL(mode)];
298 	objset_t *mos = dp->dp_meta_objset;
299 	dmu_buf_t *dbuf;
300 	dsl_dataset_t *ds;
301 	int err;
302 
303 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
304 	    dsl_pool_sync_context(dp));
305 
306 	err = dmu_bonus_hold(mos, dsobj, tag, &dbuf);
307 	if (err)
308 		return (err);
309 	ds = dmu_buf_get_user(dbuf);
310 	if (ds == NULL) {
311 		dsl_dataset_t *winner;
312 
313 		ds = kmem_zalloc(sizeof (dsl_dataset_t), KM_SLEEP);
314 		ds->ds_dbuf = dbuf;
315 		ds->ds_object = dsobj;
316 		ds->ds_phys = dbuf->db_data;
317 
318 		mutex_init(&ds->ds_lock, NULL, MUTEX_DEFAULT, NULL);
319 		mutex_init(&ds->ds_opening_lock, NULL, MUTEX_DEFAULT, NULL);
320 		mutex_init(&ds->ds_deadlist.bpl_lock, NULL, MUTEX_DEFAULT,
321 		    NULL);
322 
323 		err = bplist_open(&ds->ds_deadlist,
324 		    mos, ds->ds_phys->ds_deadlist_obj);
325 		if (err == 0) {
326 			err = dsl_dir_open_obj(dp,
327 			    ds->ds_phys->ds_dir_obj, NULL, ds, &ds->ds_dir);
328 		}
329 		if (err) {
330 			/*
331 			 * we don't really need to close the blist if we
332 			 * just opened it.
333 			 */
334 			mutex_destroy(&ds->ds_lock);
335 			mutex_destroy(&ds->ds_opening_lock);
336 			mutex_destroy(&ds->ds_deadlist.bpl_lock);
337 			kmem_free(ds, sizeof (dsl_dataset_t));
338 			dmu_buf_rele(dbuf, tag);
339 			return (err);
340 		}
341 
342 		if (ds->ds_dir->dd_phys->dd_head_dataset_obj == dsobj) {
343 			ds->ds_snapname[0] = '\0';
344 			if (ds->ds_phys->ds_prev_snap_obj) {
345 				err = dsl_dataset_open_obj(dp,
346 				    ds->ds_phys->ds_prev_snap_obj, NULL,
347 				    DS_MODE_NONE, ds, &ds->ds_prev);
348 			}
349 		} else {
350 			if (snapname) {
351 #ifdef ZFS_DEBUG
352 				dsl_dataset_phys_t *headphys;
353 				dmu_buf_t *headdbuf;
354 				err = dmu_bonus_hold(mos,
355 				    ds->ds_dir->dd_phys->dd_head_dataset_obj,
356 				    FTAG, &headdbuf);
357 				if (err == 0) {
358 					headphys = headdbuf->db_data;
359 					uint64_t foundobj;
360 					err = zap_lookup(dp->dp_meta_objset,
361 					    headphys->ds_snapnames_zapobj,
362 					    snapname, sizeof (foundobj), 1,
363 					    &foundobj);
364 					ASSERT3U(foundobj, ==, dsobj);
365 					dmu_buf_rele(headdbuf, FTAG);
366 				}
367 #endif
368 				(void) strcat(ds->ds_snapname, snapname);
369 			} else if (zfs_flags & ZFS_DEBUG_SNAPNAMES) {
370 				err = dsl_dataset_get_snapname(ds);
371 			}
372 		}
373 
374 		if (!dsl_dataset_is_snapshot(ds)) {
375 			/*
376 			 * In sync context, we're called with either no lock
377 			 * or with the write lock.  If we're not syncing,
378 			 * we're always called with the read lock held.
379 			 */
380 			boolean_t need_lock =
381 			    !RW_WRITE_HELD(&dp->dp_config_rwlock) &&
382 			    dsl_pool_sync_context(dp);
383 
384 			if (need_lock)
385 				rw_enter(&dp->dp_config_rwlock, RW_READER);
386 
387 			err = dsl_prop_get_ds_locked(ds->ds_dir,
388 			    "refreservation", sizeof (uint64_t), 1,
389 			    &ds->ds_reserved, NULL);
390 			if (err == 0) {
391 				err = dsl_prop_get_ds_locked(ds->ds_dir,
392 				    "refquota", sizeof (uint64_t), 1,
393 				    &ds->ds_quota, NULL);
394 			}
395 
396 			if (need_lock)
397 				rw_exit(&dp->dp_config_rwlock);
398 		} else {
399 			ds->ds_reserved = ds->ds_quota = 0;
400 		}
401 
402 		if (err == 0) {
403 			winner = dmu_buf_set_user_ie(dbuf, ds, &ds->ds_phys,
404 			    dsl_dataset_evict);
405 		}
406 		if (err || winner) {
407 			bplist_close(&ds->ds_deadlist);
408 			if (ds->ds_prev) {
409 				dsl_dataset_close(ds->ds_prev,
410 				    DS_MODE_NONE, ds);
411 			}
412 			dsl_dir_close(ds->ds_dir, ds);
413 			mutex_destroy(&ds->ds_lock);
414 			mutex_destroy(&ds->ds_opening_lock);
415 			mutex_destroy(&ds->ds_deadlist.bpl_lock);
416 			kmem_free(ds, sizeof (dsl_dataset_t));
417 			if (err) {
418 				dmu_buf_rele(dbuf, tag);
419 				return (err);
420 			}
421 			ds = winner;
422 		} else {
423 			ds->ds_fsid_guid =
424 			    unique_insert(ds->ds_phys->ds_fsid_guid);
425 		}
426 	}
427 	ASSERT3P(ds->ds_dbuf, ==, dbuf);
428 	ASSERT3P(ds->ds_phys, ==, dbuf->db_data);
429 
430 	mutex_enter(&ds->ds_lock);
431 	if ((DS_MODE_LEVEL(mode) == DS_MODE_PRIMARY &&
432 	    (ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT) &&
433 	    !DS_MODE_IS_INCONSISTENT(mode)) ||
434 	    (ds->ds_open_refcount + weight > DS_REF_MAX)) {
435 		mutex_exit(&ds->ds_lock);
436 		dsl_dataset_close(ds, DS_MODE_NONE, tag);
437 		return (EBUSY);
438 	}
439 	ds->ds_open_refcount += weight;
440 	mutex_exit(&ds->ds_lock);
441 
442 	*dsp = ds;
443 	return (0);
444 }
445 
446 int
447 dsl_dataset_open_spa(spa_t *spa, const char *name, int mode,
448     void *tag, dsl_dataset_t **dsp)
449 {
450 	dsl_dir_t *dd;
451 	dsl_pool_t *dp;
452 	const char *tail;
453 	uint64_t obj;
454 	dsl_dataset_t *ds = NULL;
455 	int err = 0;
456 
457 	err = dsl_dir_open_spa(spa, name, FTAG, &dd, &tail);
458 	if (err)
459 		return (err);
460 
461 	dp = dd->dd_pool;
462 	obj = dd->dd_phys->dd_head_dataset_obj;
463 	rw_enter(&dp->dp_config_rwlock, RW_READER);
464 	if (obj == 0) {
465 		/* A dataset with no associated objset */
466 		err = ENOENT;
467 		goto out;
468 	}
469 
470 	if (tail != NULL) {
471 		objset_t *mos = dp->dp_meta_objset;
472 
473 		err = dsl_dataset_open_obj(dp, obj, NULL,
474 		    DS_MODE_NONE, tag, &ds);
475 		if (err)
476 			goto out;
477 		obj = ds->ds_phys->ds_snapnames_zapobj;
478 		dsl_dataset_close(ds, DS_MODE_NONE, tag);
479 		ds = NULL;
480 
481 		if (tail[0] != '@') {
482 			err = ENOENT;
483 			goto out;
484 		}
485 		tail++;
486 
487 		/* Look for a snapshot */
488 		if (!DS_MODE_IS_READONLY(mode)) {
489 			err = EROFS;
490 			goto out;
491 		}
492 		dprintf("looking for snapshot '%s'\n", tail);
493 		err = zap_lookup(mos, obj, tail, 8, 1, &obj);
494 		if (err)
495 			goto out;
496 	}
497 	err = dsl_dataset_open_obj(dp, obj, tail, mode, tag, &ds);
498 
499 out:
500 	rw_exit(&dp->dp_config_rwlock);
501 	dsl_dir_close(dd, FTAG);
502 
503 	ASSERT3U((err == 0), ==, (ds != NULL));
504 	/* ASSERT(ds == NULL || strcmp(name, ds->ds_name) == 0); */
505 
506 	*dsp = ds;
507 	return (err);
508 }
509 
510 int
511 dsl_dataset_open(const char *name, int mode, void *tag, dsl_dataset_t **dsp)
512 {
513 	return (dsl_dataset_open_spa(NULL, name, mode, tag, dsp));
514 }
515 
516 void
517 dsl_dataset_name(dsl_dataset_t *ds, char *name)
518 {
519 	if (ds == NULL) {
520 		(void) strcpy(name, "mos");
521 	} else {
522 		dsl_dir_name(ds->ds_dir, name);
523 		VERIFY(0 == dsl_dataset_get_snapname(ds));
524 		if (ds->ds_snapname[0]) {
525 			(void) strcat(name, "@");
526 			if (!MUTEX_HELD(&ds->ds_lock)) {
527 				/*
528 				 * We use a "recursive" mutex so that we
529 				 * can call dprintf_ds() with ds_lock held.
530 				 */
531 				mutex_enter(&ds->ds_lock);
532 				(void) strcat(name, ds->ds_snapname);
533 				mutex_exit(&ds->ds_lock);
534 			} else {
535 				(void) strcat(name, ds->ds_snapname);
536 			}
537 		}
538 	}
539 }
540 
541 static int
542 dsl_dataset_namelen(dsl_dataset_t *ds)
543 {
544 	int result;
545 
546 	if (ds == NULL) {
547 		result = 3;	/* "mos" */
548 	} else {
549 		result = dsl_dir_namelen(ds->ds_dir);
550 		VERIFY(0 == dsl_dataset_get_snapname(ds));
551 		if (ds->ds_snapname[0]) {
552 			++result;	/* adding one for the @-sign */
553 			if (!MUTEX_HELD(&ds->ds_lock)) {
554 				/* see dsl_datset_name */
555 				mutex_enter(&ds->ds_lock);
556 				result += strlen(ds->ds_snapname);
557 				mutex_exit(&ds->ds_lock);
558 			} else {
559 				result += strlen(ds->ds_snapname);
560 			}
561 		}
562 	}
563 
564 	return (result);
565 }
566 
567 void
568 dsl_dataset_close(dsl_dataset_t *ds, int mode, void *tag)
569 {
570 	uint64_t weight = ds_refcnt_weight[DS_MODE_LEVEL(mode)];
571 	mutex_enter(&ds->ds_lock);
572 	ASSERT3U(ds->ds_open_refcount, >=, weight);
573 	ds->ds_open_refcount -= weight;
574 	dprintf_ds(ds, "closing mode %u refcount now 0x%llx\n",
575 	    mode, ds->ds_open_refcount);
576 	mutex_exit(&ds->ds_lock);
577 
578 	dmu_buf_rele(ds->ds_dbuf, tag);
579 }
580 
581 void
582 dsl_dataset_downgrade(dsl_dataset_t *ds, int oldmode, int newmode)
583 {
584 	uint64_t oldweight = ds_refcnt_weight[DS_MODE_LEVEL(oldmode)];
585 	uint64_t newweight = ds_refcnt_weight[DS_MODE_LEVEL(newmode)];
586 	mutex_enter(&ds->ds_lock);
587 	ASSERT3U(ds->ds_open_refcount, >=, oldweight);
588 	ASSERT3U(oldweight, >=, newweight);
589 	ds->ds_open_refcount -= oldweight;
590 	ds->ds_open_refcount += newweight;
591 	mutex_exit(&ds->ds_lock);
592 }
593 
594 boolean_t
595 dsl_dataset_tryupgrade(dsl_dataset_t *ds, int oldmode, int newmode)
596 {
597 	boolean_t rv;
598 	uint64_t oldweight = ds_refcnt_weight[DS_MODE_LEVEL(oldmode)];
599 	uint64_t newweight = ds_refcnt_weight[DS_MODE_LEVEL(newmode)];
600 	mutex_enter(&ds->ds_lock);
601 	ASSERT3U(ds->ds_open_refcount, >=, oldweight);
602 	ASSERT3U(newweight, >=, oldweight);
603 	if (ds->ds_open_refcount - oldweight + newweight > DS_REF_MAX) {
604 		rv = B_FALSE;
605 	} else {
606 		ds->ds_open_refcount -= oldweight;
607 		ds->ds_open_refcount += newweight;
608 		rv = B_TRUE;
609 	}
610 	mutex_exit(&ds->ds_lock);
611 	return (rv);
612 }
613 
614 void
615 dsl_dataset_create_root(dsl_pool_t *dp, uint64_t *ddobjp, dmu_tx_t *tx)
616 {
617 	objset_t *mos = dp->dp_meta_objset;
618 	dmu_buf_t *dbuf;
619 	dsl_dataset_phys_t *dsphys;
620 	dsl_dataset_t *ds;
621 	uint64_t dsobj;
622 	dsl_dir_t *dd;
623 
624 	dsl_dir_create_root(mos, ddobjp, tx);
625 	VERIFY(0 == dsl_dir_open_obj(dp, *ddobjp, NULL, FTAG, &dd));
626 
627 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
628 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
629 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
630 	dmu_buf_will_dirty(dbuf, tx);
631 	dsphys = dbuf->db_data;
632 	dsphys->ds_dir_obj = dd->dd_object;
633 	dsphys->ds_fsid_guid = unique_create();
634 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
635 	    sizeof (dsphys->ds_guid));
636 	dsphys->ds_snapnames_zapobj =
637 	    zap_create(mos, DMU_OT_DSL_DS_SNAP_MAP, DMU_OT_NONE, 0, tx);
638 	dsphys->ds_creation_time = gethrestime_sec();
639 	dsphys->ds_creation_txg = tx->tx_txg;
640 	dsphys->ds_deadlist_obj =
641 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
642 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
643 		dsphys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
644 	dmu_buf_rele(dbuf, FTAG);
645 
646 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
647 	dd->dd_phys->dd_head_dataset_obj = dsobj;
648 	dsl_dir_close(dd, FTAG);
649 
650 	VERIFY(0 ==
651 	    dsl_dataset_open_obj(dp, dsobj, NULL, DS_MODE_NONE, FTAG, &ds));
652 	(void) dmu_objset_create_impl(dp->dp_spa, ds,
653 	    &ds->ds_phys->ds_bp, DMU_OST_ZFS, tx);
654 	dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
655 }
656 
657 uint64_t
658 dsl_dataset_create_sync_impl(dsl_dir_t *dd, dsl_dataset_t *origin, dmu_tx_t *tx)
659 {
660 	dsl_pool_t *dp = dd->dd_pool;
661 	dmu_buf_t *dbuf;
662 	dsl_dataset_phys_t *dsphys;
663 	uint64_t dsobj;
664 	objset_t *mos = dp->dp_meta_objset;
665 
666 	ASSERT(origin == NULL || origin->ds_dir->dd_pool == dp);
667 	ASSERT(origin == NULL || origin->ds_phys->ds_num_children > 0);
668 	ASSERT(dmu_tx_is_syncing(tx));
669 	ASSERT(dd->dd_phys->dd_head_dataset_obj == 0);
670 
671 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
672 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
673 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
674 	dmu_buf_will_dirty(dbuf, tx);
675 	dsphys = dbuf->db_data;
676 	dsphys->ds_dir_obj = dd->dd_object;
677 	dsphys->ds_fsid_guid = unique_create();
678 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
679 	    sizeof (dsphys->ds_guid));
680 	dsphys->ds_snapnames_zapobj =
681 	    zap_create(mos, DMU_OT_DSL_DS_SNAP_MAP, DMU_OT_NONE, 0, tx);
682 	dsphys->ds_creation_time = gethrestime_sec();
683 	dsphys->ds_creation_txg = tx->tx_txg;
684 	dsphys->ds_deadlist_obj =
685 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
686 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
687 		dsphys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
688 
689 	if (origin) {
690 		dsphys->ds_prev_snap_obj = origin->ds_object;
691 		dsphys->ds_prev_snap_txg =
692 		    origin->ds_phys->ds_creation_txg;
693 		dsphys->ds_used_bytes =
694 		    origin->ds_phys->ds_used_bytes;
695 		dsphys->ds_compressed_bytes =
696 		    origin->ds_phys->ds_compressed_bytes;
697 		dsphys->ds_uncompressed_bytes =
698 		    origin->ds_phys->ds_uncompressed_bytes;
699 		dsphys->ds_bp = origin->ds_phys->ds_bp;
700 
701 		dmu_buf_will_dirty(origin->ds_dbuf, tx);
702 		origin->ds_phys->ds_num_children++;
703 
704 		dmu_buf_will_dirty(dd->dd_dbuf, tx);
705 		dd->dd_phys->dd_origin_obj = origin->ds_object;
706 	}
707 	dmu_buf_rele(dbuf, FTAG);
708 
709 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
710 	dd->dd_phys->dd_head_dataset_obj = dsobj;
711 
712 	return (dsobj);
713 }
714 
715 uint64_t
716 dsl_dataset_create_sync(dsl_dir_t *pdd,
717     const char *lastname, dsl_dataset_t *origin, cred_t *cr, dmu_tx_t *tx)
718 {
719 	dsl_pool_t *dp = pdd->dd_pool;
720 	uint64_t dsobj, ddobj;
721 	dsl_dir_t *dd;
722 
723 	ASSERT(lastname[0] != '@');
724 
725 	ddobj = dsl_dir_create_sync(pdd, lastname, tx);
726 	VERIFY(0 == dsl_dir_open_obj(dp, ddobj, lastname, FTAG, &dd));
727 
728 	dsobj = dsl_dataset_create_sync_impl(dd, origin, tx);
729 
730 	dsl_deleg_set_create_perms(dd, tx, cr);
731 
732 	dsl_dir_close(dd, FTAG);
733 
734 	return (dsobj);
735 }
736 
737 struct destroyarg {
738 	dsl_sync_task_group_t *dstg;
739 	char *snapname;
740 	char *failed;
741 };
742 
743 static int
744 dsl_snapshot_destroy_one(char *name, void *arg)
745 {
746 	struct destroyarg *da = arg;
747 	dsl_dataset_t *ds;
748 	char *cp;
749 	int err;
750 
751 	(void) strcat(name, "@");
752 	(void) strcat(name, da->snapname);
753 	err = dsl_dataset_open(name,
754 	    DS_MODE_EXCLUSIVE | DS_MODE_READONLY | DS_MODE_INCONSISTENT,
755 	    da->dstg, &ds);
756 	cp = strchr(name, '@');
757 	*cp = '\0';
758 	if (err == ENOENT)
759 		return (0);
760 	if (err) {
761 		(void) strcpy(da->failed, name);
762 		return (err);
763 	}
764 
765 	dsl_sync_task_create(da->dstg, dsl_dataset_destroy_check,
766 	    dsl_dataset_destroy_sync, ds, da->dstg, 0);
767 	return (0);
768 }
769 
770 /*
771  * Destroy 'snapname' in all descendants of 'fsname'.
772  */
773 #pragma weak dmu_snapshots_destroy = dsl_snapshots_destroy
774 int
775 dsl_snapshots_destroy(char *fsname, char *snapname)
776 {
777 	int err;
778 	struct destroyarg da;
779 	dsl_sync_task_t *dst;
780 	spa_t *spa;
781 
782 	err = spa_open(fsname, &spa, FTAG);
783 	if (err)
784 		return (err);
785 	da.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
786 	da.snapname = snapname;
787 	da.failed = fsname;
788 
789 	err = dmu_objset_find(fsname,
790 	    dsl_snapshot_destroy_one, &da, DS_FIND_CHILDREN);
791 
792 	if (err == 0)
793 		err = dsl_sync_task_group_wait(da.dstg);
794 
795 	for (dst = list_head(&da.dstg->dstg_tasks); dst;
796 	    dst = list_next(&da.dstg->dstg_tasks, dst)) {
797 		dsl_dataset_t *ds = dst->dst_arg1;
798 		if (dst->dst_err) {
799 			dsl_dataset_name(ds, fsname);
800 			*strchr(fsname, '@') = '\0';
801 		}
802 		/*
803 		 * If it was successful, destroy_sync would have
804 		 * closed the ds
805 		 */
806 		if (err)
807 			dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, da.dstg);
808 	}
809 
810 	dsl_sync_task_group_destroy(da.dstg);
811 	spa_close(spa, FTAG);
812 	return (err);
813 }
814 
815 /*
816  * ds must be opened EXCLUSIVE or PRIMARY.  on return (whether
817  * successful or not), ds will be closed and caller can no longer
818  * dereference it.
819  */
820 int
821 dsl_dataset_destroy(dsl_dataset_t *ds, void *tag)
822 {
823 	int err;
824 	dsl_sync_task_group_t *dstg;
825 	objset_t *os;
826 	dsl_dir_t *dd;
827 	uint64_t obj;
828 
829 	if (ds->ds_open_refcount != DS_REF_MAX) {
830 		if (dsl_dataset_tryupgrade(ds, DS_MODE_PRIMARY,
831 		    DS_MODE_EXCLUSIVE) == 0) {
832 			dsl_dataset_close(ds, DS_MODE_PRIMARY, tag);
833 			return (EBUSY);
834 		}
835 	}
836 
837 	if (dsl_dataset_is_snapshot(ds)) {
838 		/* Destroying a snapshot is simpler */
839 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
840 		    dsl_dataset_destroy_check, dsl_dataset_destroy_sync,
841 		    ds, tag, 0);
842 		goto out;
843 	}
844 
845 	dd = ds->ds_dir;
846 
847 	/*
848 	 * Check for errors and mark this ds as inconsistent, in
849 	 * case we crash while freeing the objects.
850 	 */
851 	err = dsl_sync_task_do(dd->dd_pool, dsl_dataset_destroy_begin_check,
852 	    dsl_dataset_destroy_begin_sync, ds, NULL, 0);
853 	if (err)
854 		goto out;
855 
856 	err = dmu_objset_open_ds(ds, DMU_OST_ANY, &os);
857 	if (err)
858 		goto out;
859 
860 	/*
861 	 * remove the objects in open context, so that we won't
862 	 * have too much to do in syncing context.
863 	 */
864 	for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE,
865 	    ds->ds_phys->ds_prev_snap_txg)) {
866 		dmu_tx_t *tx = dmu_tx_create(os);
867 		dmu_tx_hold_free(tx, obj, 0, DMU_OBJECT_END);
868 		dmu_tx_hold_bonus(tx, obj);
869 		err = dmu_tx_assign(tx, TXG_WAIT);
870 		if (err) {
871 			/*
872 			 * Perhaps there is not enough disk
873 			 * space.  Just deal with it from
874 			 * dsl_dataset_destroy_sync().
875 			 */
876 			dmu_tx_abort(tx);
877 			continue;
878 		}
879 		VERIFY(0 == dmu_object_free(os, obj, tx));
880 		dmu_tx_commit(tx);
881 	}
882 	/* Make sure it's not dirty before we finish destroying it. */
883 	txg_wait_synced(dd->dd_pool, 0);
884 
885 	dmu_objset_close(os);
886 	if (err != ESRCH)
887 		goto out;
888 
889 	if (ds->ds_user_ptr) {
890 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
891 		ds->ds_user_ptr = NULL;
892 	}
893 
894 	rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
895 	err = dsl_dir_open_obj(dd->dd_pool, dd->dd_object, NULL, FTAG, &dd);
896 	rw_exit(&dd->dd_pool->dp_config_rwlock);
897 
898 	if (err)
899 		goto out;
900 
901 	/*
902 	 * Blow away the dsl_dir + head dataset.
903 	 */
904 	dstg = dsl_sync_task_group_create(ds->ds_dir->dd_pool);
905 	dsl_sync_task_create(dstg, dsl_dataset_destroy_check,
906 	    dsl_dataset_destroy_sync, ds, tag, 0);
907 	dsl_sync_task_create(dstg, dsl_dir_destroy_check,
908 	    dsl_dir_destroy_sync, dd, FTAG, 0);
909 	err = dsl_sync_task_group_wait(dstg);
910 	dsl_sync_task_group_destroy(dstg);
911 	/* if it is successful, *destroy_sync will close the ds+dd */
912 	if (err)
913 		dsl_dir_close(dd, FTAG);
914 out:
915 	if (err)
916 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, tag);
917 	return (err);
918 }
919 
920 int
921 dsl_dataset_rollback(dsl_dataset_t *ds, dmu_objset_type_t ost)
922 {
923 	ASSERT3U(ds->ds_open_refcount, ==, DS_REF_MAX);
924 
925 	return (dsl_sync_task_do(ds->ds_dir->dd_pool,
926 	    dsl_dataset_rollback_check, dsl_dataset_rollback_sync,
927 	    ds, &ost, 0));
928 }
929 
930 void *
931 dsl_dataset_set_user_ptr(dsl_dataset_t *ds,
932     void *p, dsl_dataset_evict_func_t func)
933 {
934 	void *old;
935 
936 	mutex_enter(&ds->ds_lock);
937 	old = ds->ds_user_ptr;
938 	if (old == NULL) {
939 		ds->ds_user_ptr = p;
940 		ds->ds_user_evict_func = func;
941 	}
942 	mutex_exit(&ds->ds_lock);
943 	return (old);
944 }
945 
946 void *
947 dsl_dataset_get_user_ptr(dsl_dataset_t *ds)
948 {
949 	return (ds->ds_user_ptr);
950 }
951 
952 
953 blkptr_t *
954 dsl_dataset_get_blkptr(dsl_dataset_t *ds)
955 {
956 	return (&ds->ds_phys->ds_bp);
957 }
958 
959 void
960 dsl_dataset_set_blkptr(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
961 {
962 	ASSERT(dmu_tx_is_syncing(tx));
963 	/* If it's the meta-objset, set dp_meta_rootbp */
964 	if (ds == NULL) {
965 		tx->tx_pool->dp_meta_rootbp = *bp;
966 	} else {
967 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
968 		ds->ds_phys->ds_bp = *bp;
969 	}
970 }
971 
972 spa_t *
973 dsl_dataset_get_spa(dsl_dataset_t *ds)
974 {
975 	return (ds->ds_dir->dd_pool->dp_spa);
976 }
977 
978 void
979 dsl_dataset_dirty(dsl_dataset_t *ds, dmu_tx_t *tx)
980 {
981 	dsl_pool_t *dp;
982 
983 	if (ds == NULL) /* this is the meta-objset */
984 		return;
985 
986 	ASSERT(ds->ds_user_ptr != NULL);
987 
988 	if (ds->ds_phys->ds_next_snap_obj != 0)
989 		panic("dirtying snapshot!");
990 
991 	dp = ds->ds_dir->dd_pool;
992 
993 	if (txg_list_add(&dp->dp_dirty_datasets, ds, tx->tx_txg) == 0) {
994 		/* up the hold count until we can be written out */
995 		dmu_buf_add_ref(ds->ds_dbuf, ds);
996 	}
997 }
998 
999 /*
1000  * The unique space in the head dataset can be calculated by subtracting
1001  * the space used in the most recent snapshot, that is still being used
1002  * in this file system, from the space currently in use.  To figure out
1003  * the space in the most recent snapshot still in use, we need to take
1004  * the total space used in the snapshot and subtract out the space that
1005  * has been freed up since the snapshot was taken.
1006  */
1007 static void
1008 dsl_dataset_recalc_head_uniq(dsl_dataset_t *ds)
1009 {
1010 	uint64_t mrs_used;
1011 	uint64_t dlused, dlcomp, dluncomp;
1012 
1013 	ASSERT(ds->ds_object == ds->ds_dir->dd_phys->dd_head_dataset_obj);
1014 
1015 	if (ds->ds_phys->ds_prev_snap_obj != 0)
1016 		mrs_used = ds->ds_prev->ds_phys->ds_used_bytes;
1017 	else
1018 		mrs_used = 0;
1019 
1020 	VERIFY(0 == bplist_space(&ds->ds_deadlist, &dlused, &dlcomp,
1021 	    &dluncomp));
1022 
1023 	ASSERT3U(dlused, <=, mrs_used);
1024 	ds->ds_phys->ds_unique_bytes =
1025 	    ds->ds_phys->ds_used_bytes - (mrs_used - dlused);
1026 
1027 	if (!DS_UNIQUE_IS_ACCURATE(ds) &&
1028 	    spa_version(ds->ds_dir->dd_pool->dp_spa) >=
1029 	    SPA_VERSION_UNIQUE_ACCURATE)
1030 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
1031 }
1032 
1033 static uint64_t
1034 dsl_dataset_unique(dsl_dataset_t *ds)
1035 {
1036 	if (!DS_UNIQUE_IS_ACCURATE(ds) && !dsl_dataset_is_snapshot(ds))
1037 		dsl_dataset_recalc_head_uniq(ds);
1038 
1039 	return (ds->ds_phys->ds_unique_bytes);
1040 }
1041 
1042 struct killarg {
1043 	int64_t *usedp;
1044 	int64_t *compressedp;
1045 	int64_t *uncompressedp;
1046 	zio_t *zio;
1047 	dmu_tx_t *tx;
1048 };
1049 
1050 static int
1051 kill_blkptr(traverse_blk_cache_t *bc, spa_t *spa, void *arg)
1052 {
1053 	struct killarg *ka = arg;
1054 	blkptr_t *bp = &bc->bc_blkptr;
1055 
1056 	ASSERT3U(bc->bc_errno, ==, 0);
1057 
1058 	/*
1059 	 * Since this callback is not called concurrently, no lock is
1060 	 * needed on the accounting values.
1061 	 */
1062 	*ka->usedp += bp_get_dasize(spa, bp);
1063 	*ka->compressedp += BP_GET_PSIZE(bp);
1064 	*ka->uncompressedp += BP_GET_UCSIZE(bp);
1065 	/* XXX check for EIO? */
1066 	(void) arc_free(ka->zio, spa, ka->tx->tx_txg, bp, NULL, NULL,
1067 	    ARC_NOWAIT);
1068 	return (0);
1069 }
1070 
1071 /* ARGSUSED */
1072 static int
1073 dsl_dataset_rollback_check(void *arg1, void *arg2, dmu_tx_t *tx)
1074 {
1075 	dsl_dataset_t *ds = arg1;
1076 	dmu_objset_type_t *ost = arg2;
1077 
1078 	/*
1079 	 * We can only roll back to emptyness if it is a ZPL objset.
1080 	 */
1081 	if (*ost != DMU_OST_ZFS && ds->ds_phys->ds_prev_snap_txg == 0)
1082 		return (EINVAL);
1083 
1084 	/*
1085 	 * This must not be a snapshot.
1086 	 */
1087 	if (ds->ds_phys->ds_next_snap_obj != 0)
1088 		return (EINVAL);
1089 
1090 	/*
1091 	 * If we made changes this txg, traverse_dsl_dataset won't find
1092 	 * them.  Try again.
1093 	 */
1094 	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
1095 		return (EAGAIN);
1096 
1097 	return (0);
1098 }
1099 
1100 /* ARGSUSED */
1101 static void
1102 dsl_dataset_rollback_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1103 {
1104 	dsl_dataset_t *ds = arg1;
1105 	dmu_objset_type_t *ost = arg2;
1106 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
1107 
1108 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1109 
1110 	/*
1111 	 * Before the roll back destroy the zil.
1112 	 */
1113 	if (ds->ds_user_ptr != NULL) {
1114 		zil_rollback_destroy(
1115 		    ((objset_impl_t *)ds->ds_user_ptr)->os_zil, tx);
1116 
1117 		/*
1118 		 * We need to make sure that the objset_impl_t is reopened after
1119 		 * we do the rollback, otherwise it will have the wrong
1120 		 * objset_phys_t.  Normally this would happen when this
1121 		 * DS_MODE_EXCLUSIVE dataset-open is closed, thus causing the
1122 		 * dataset to be immediately evicted.  But when doing "zfs recv
1123 		 * -F", we reopen the objset before that, so that there is no
1124 		 * window where the dataset is closed and inconsistent.
1125 		 */
1126 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
1127 		ds->ds_user_ptr = NULL;
1128 	}
1129 
1130 	/* Zero out the deadlist. */
1131 	bplist_close(&ds->ds_deadlist);
1132 	bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
1133 	ds->ds_phys->ds_deadlist_obj =
1134 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
1135 	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
1136 	    ds->ds_phys->ds_deadlist_obj));
1137 
1138 	{
1139 		/* Free blkptrs that we gave birth to */
1140 		zio_t *zio;
1141 		int64_t used = 0, compressed = 0, uncompressed = 0;
1142 		struct killarg ka;
1143 		int64_t delta;
1144 
1145 		zio = zio_root(tx->tx_pool->dp_spa, NULL, NULL,
1146 		    ZIO_FLAG_MUSTSUCCEED);
1147 		ka.usedp = &used;
1148 		ka.compressedp = &compressed;
1149 		ka.uncompressedp = &uncompressed;
1150 		ka.zio = zio;
1151 		ka.tx = tx;
1152 		(void) traverse_dsl_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
1153 		    ADVANCE_POST, kill_blkptr, &ka);
1154 		(void) zio_wait(zio);
1155 
1156 		/* only deduct space beyond any refreservation */
1157 		delta = parent_delta(ds, -used);
1158 		dsl_dir_diduse_space(ds->ds_dir,
1159 		    delta, -compressed, -uncompressed, tx);
1160 	}
1161 
1162 	if (ds->ds_prev) {
1163 		/* Change our contents to that of the prev snapshot */
1164 		ASSERT3U(ds->ds_prev->ds_object, ==,
1165 		    ds->ds_phys->ds_prev_snap_obj);
1166 		ds->ds_phys->ds_bp = ds->ds_prev->ds_phys->ds_bp;
1167 		ds->ds_phys->ds_used_bytes =
1168 		    ds->ds_prev->ds_phys->ds_used_bytes;
1169 		ds->ds_phys->ds_compressed_bytes =
1170 		    ds->ds_prev->ds_phys->ds_compressed_bytes;
1171 		ds->ds_phys->ds_uncompressed_bytes =
1172 		    ds->ds_prev->ds_phys->ds_uncompressed_bytes;
1173 		ds->ds_phys->ds_flags = ds->ds_prev->ds_phys->ds_flags;
1174 		ds->ds_phys->ds_unique_bytes = 0;
1175 
1176 		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
1177 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
1178 			ds->ds_prev->ds_phys->ds_unique_bytes = 0;
1179 		}
1180 	} else {
1181 		/* Zero out our contents, recreate objset */
1182 		bzero(&ds->ds_phys->ds_bp, sizeof (blkptr_t));
1183 		ds->ds_phys->ds_used_bytes = 0;
1184 		ds->ds_phys->ds_compressed_bytes = 0;
1185 		ds->ds_phys->ds_uncompressed_bytes = 0;
1186 		ds->ds_phys->ds_flags = 0;
1187 		ds->ds_phys->ds_unique_bytes = 0;
1188 		(void) dmu_objset_create_impl(ds->ds_dir->dd_pool->dp_spa, ds,
1189 		    &ds->ds_phys->ds_bp, *ost, tx);
1190 	}
1191 
1192 	spa_history_internal_log(LOG_DS_ROLLBACK, ds->ds_dir->dd_pool->dp_spa,
1193 	    tx, cr, "dataset = %llu", ds->ds_object);
1194 }
1195 
1196 /* ARGSUSED */
1197 static int
1198 dsl_dataset_destroy_begin_check(void *arg1, void *arg2, dmu_tx_t *tx)
1199 {
1200 	dsl_dataset_t *ds = arg1;
1201 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
1202 	uint64_t count;
1203 	int err;
1204 
1205 	/*
1206 	 * Can't delete a head dataset if there are snapshots of it.
1207 	 * (Except if the only snapshots are from the branch we cloned
1208 	 * from.)
1209 	 */
1210 	if (ds->ds_prev != NULL &&
1211 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
1212 		return (EINVAL);
1213 
1214 	/*
1215 	 * This is really a dsl_dir thing, but check it here so that
1216 	 * we'll be less likely to leave this dataset inconsistent &
1217 	 * nearly destroyed.
1218 	 */
1219 	err = zap_count(mos, ds->ds_dir->dd_phys->dd_child_dir_zapobj, &count);
1220 	if (err)
1221 		return (err);
1222 	if (count != 0)
1223 		return (EEXIST);
1224 
1225 	return (0);
1226 }
1227 
1228 /* ARGSUSED */
1229 static void
1230 dsl_dataset_destroy_begin_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1231 {
1232 	dsl_dataset_t *ds = arg1;
1233 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1234 
1235 	/* Mark it as inconsistent on-disk, in case we crash */
1236 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1237 	ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
1238 
1239 	spa_history_internal_log(LOG_DS_DESTROY_BEGIN, dp->dp_spa, tx,
1240 	    cr, "dataset = %llu", ds->ds_object);
1241 }
1242 
1243 /* ARGSUSED */
1244 int
1245 dsl_dataset_destroy_check(void *arg1, void *arg2, dmu_tx_t *tx)
1246 {
1247 	dsl_dataset_t *ds = arg1;
1248 
1249 	/* Can't delete a branch point. */
1250 	if (ds->ds_phys->ds_num_children > 1)
1251 		return (EEXIST);
1252 
1253 	/*
1254 	 * Can't delete a head dataset if there are snapshots of it.
1255 	 * (Except if the only snapshots are from the branch we cloned
1256 	 * from.)
1257 	 */
1258 	if (ds->ds_prev != NULL &&
1259 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
1260 		return (EINVAL);
1261 
1262 	/*
1263 	 * If we made changes this txg, traverse_dsl_dataset won't find
1264 	 * them.  Try again.
1265 	 */
1266 	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
1267 		return (EAGAIN);
1268 
1269 	/* XXX we should do some i/o error checking... */
1270 	return (0);
1271 }
1272 
1273 void
1274 dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
1275 {
1276 	dsl_dataset_t *ds = arg1;
1277 	int64_t used = 0, compressed = 0, uncompressed = 0;
1278 	zio_t *zio;
1279 	int err;
1280 	int after_branch_point = FALSE;
1281 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1282 	objset_t *mos = dp->dp_meta_objset;
1283 	dsl_dataset_t *ds_prev = NULL;
1284 	uint64_t obj;
1285 
1286 	ASSERT3U(ds->ds_open_refcount, ==, DS_REF_MAX);
1287 	ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
1288 	ASSERT(ds->ds_prev == NULL ||
1289 	    ds->ds_prev->ds_phys->ds_next_snap_obj != ds->ds_object);
1290 	ASSERT3U(ds->ds_phys->ds_bp.blk_birth, <=, tx->tx_txg);
1291 
1292 	/* Remove our reservation */
1293 	if (ds->ds_reserved != 0) {
1294 		uint64_t val = 0;
1295 		dsl_dataset_set_reservation_sync(ds, &val, cr, tx);
1296 		ASSERT3U(ds->ds_reserved, ==, 0);
1297 	}
1298 
1299 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
1300 
1301 	obj = ds->ds_object;
1302 
1303 	if (ds->ds_phys->ds_prev_snap_obj != 0) {
1304 		if (ds->ds_prev) {
1305 			ds_prev = ds->ds_prev;
1306 		} else {
1307 			VERIFY(0 == dsl_dataset_open_obj(dp,
1308 			    ds->ds_phys->ds_prev_snap_obj, NULL,
1309 			    DS_MODE_NONE, FTAG, &ds_prev));
1310 		}
1311 		after_branch_point =
1312 		    (ds_prev->ds_phys->ds_next_snap_obj != obj);
1313 
1314 		dmu_buf_will_dirty(ds_prev->ds_dbuf, tx);
1315 		if (after_branch_point &&
1316 		    ds->ds_phys->ds_next_snap_obj == 0) {
1317 			/* This clone is toast. */
1318 			ASSERT(ds_prev->ds_phys->ds_num_children > 1);
1319 			ds_prev->ds_phys->ds_num_children--;
1320 		} else if (!after_branch_point) {
1321 			ds_prev->ds_phys->ds_next_snap_obj =
1322 			    ds->ds_phys->ds_next_snap_obj;
1323 		}
1324 	}
1325 
1326 	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
1327 
1328 	if (ds->ds_phys->ds_next_snap_obj != 0) {
1329 		blkptr_t bp;
1330 		dsl_dataset_t *ds_next;
1331 		uint64_t itor = 0;
1332 		uint64_t old_unique;
1333 
1334 		spa_scrub_restart(dp->dp_spa, tx->tx_txg);
1335 
1336 		VERIFY(0 == dsl_dataset_open_obj(dp,
1337 		    ds->ds_phys->ds_next_snap_obj, NULL,
1338 		    DS_MODE_NONE, FTAG, &ds_next));
1339 		ASSERT3U(ds_next->ds_phys->ds_prev_snap_obj, ==, obj);
1340 
1341 		old_unique = dsl_dataset_unique(ds_next);
1342 
1343 		dmu_buf_will_dirty(ds_next->ds_dbuf, tx);
1344 		ds_next->ds_phys->ds_prev_snap_obj =
1345 		    ds->ds_phys->ds_prev_snap_obj;
1346 		ds_next->ds_phys->ds_prev_snap_txg =
1347 		    ds->ds_phys->ds_prev_snap_txg;
1348 		ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
1349 		    ds_prev ? ds_prev->ds_phys->ds_creation_txg : 0);
1350 
1351 		/*
1352 		 * Transfer to our deadlist (which will become next's
1353 		 * new deadlist) any entries from next's current
1354 		 * deadlist which were born before prev, and free the
1355 		 * other entries.
1356 		 *
1357 		 * XXX we're doing this long task with the config lock held
1358 		 */
1359 		while (bplist_iterate(&ds_next->ds_deadlist, &itor,
1360 		    &bp) == 0) {
1361 			if (bp.blk_birth <= ds->ds_phys->ds_prev_snap_txg) {
1362 				VERIFY(0 == bplist_enqueue(&ds->ds_deadlist,
1363 				    &bp, tx));
1364 				if (ds_prev && !after_branch_point &&
1365 				    bp.blk_birth >
1366 				    ds_prev->ds_phys->ds_prev_snap_txg) {
1367 					ds_prev->ds_phys->ds_unique_bytes +=
1368 					    bp_get_dasize(dp->dp_spa, &bp);
1369 				}
1370 			} else {
1371 				used += bp_get_dasize(dp->dp_spa, &bp);
1372 				compressed += BP_GET_PSIZE(&bp);
1373 				uncompressed += BP_GET_UCSIZE(&bp);
1374 				/* XXX check return value? */
1375 				(void) arc_free(zio, dp->dp_spa, tx->tx_txg,
1376 				    &bp, NULL, NULL, ARC_NOWAIT);
1377 			}
1378 		}
1379 
1380 		/* free next's deadlist */
1381 		bplist_close(&ds_next->ds_deadlist);
1382 		bplist_destroy(mos, ds_next->ds_phys->ds_deadlist_obj, tx);
1383 
1384 		/* set next's deadlist to our deadlist */
1385 		ds_next->ds_phys->ds_deadlist_obj =
1386 		    ds->ds_phys->ds_deadlist_obj;
1387 		VERIFY(0 == bplist_open(&ds_next->ds_deadlist, mos,
1388 		    ds_next->ds_phys->ds_deadlist_obj));
1389 		ds->ds_phys->ds_deadlist_obj = 0;
1390 
1391 		if (ds_next->ds_phys->ds_next_snap_obj != 0) {
1392 			/*
1393 			 * Update next's unique to include blocks which
1394 			 * were previously shared by only this snapshot
1395 			 * and it.  Those blocks will be born after the
1396 			 * prev snap and before this snap, and will have
1397 			 * died after the next snap and before the one
1398 			 * after that (ie. be on the snap after next's
1399 			 * deadlist).
1400 			 *
1401 			 * XXX we're doing this long task with the
1402 			 * config lock held
1403 			 */
1404 			dsl_dataset_t *ds_after_next;
1405 
1406 			VERIFY(0 == dsl_dataset_open_obj(dp,
1407 			    ds_next->ds_phys->ds_next_snap_obj, NULL,
1408 			    DS_MODE_NONE, FTAG, &ds_after_next));
1409 			itor = 0;
1410 			while (bplist_iterate(&ds_after_next->ds_deadlist,
1411 			    &itor, &bp) == 0) {
1412 				if (bp.blk_birth >
1413 				    ds->ds_phys->ds_prev_snap_txg &&
1414 				    bp.blk_birth <=
1415 				    ds->ds_phys->ds_creation_txg) {
1416 					ds_next->ds_phys->ds_unique_bytes +=
1417 					    bp_get_dasize(dp->dp_spa, &bp);
1418 				}
1419 			}
1420 
1421 			dsl_dataset_close(ds_after_next, DS_MODE_NONE, FTAG);
1422 			ASSERT3P(ds_next->ds_prev, ==, NULL);
1423 		} else {
1424 			ASSERT3P(ds_next->ds_prev, ==, ds);
1425 			dsl_dataset_close(ds_next->ds_prev, DS_MODE_NONE,
1426 			    ds_next);
1427 			if (ds_prev) {
1428 				VERIFY(0 == dsl_dataset_open_obj(dp,
1429 				    ds->ds_phys->ds_prev_snap_obj, NULL,
1430 				    DS_MODE_NONE, ds_next, &ds_next->ds_prev));
1431 			} else {
1432 				ds_next->ds_prev = NULL;
1433 			}
1434 
1435 			dsl_dataset_recalc_head_uniq(ds_next);
1436 
1437 			/*
1438 			 * Reduce the amount of our unconsmed refreservation
1439 			 * being charged to our parent by the amount of
1440 			 * new unique data we have gained.
1441 			 */
1442 			if (old_unique < ds_next->ds_reserved) {
1443 				int64_t mrsdelta;
1444 				uint64_t new_unique =
1445 				    ds_next->ds_phys->ds_unique_bytes;
1446 
1447 				ASSERT(old_unique <= new_unique);
1448 				mrsdelta = MIN(new_unique - old_unique,
1449 				    ds_next->ds_reserved - old_unique);
1450 				dsl_dir_diduse_space(ds->ds_dir, -mrsdelta,
1451 				    0, 0, tx);
1452 			}
1453 		}
1454 		dsl_dataset_close(ds_next, DS_MODE_NONE, FTAG);
1455 
1456 		/*
1457 		 * NB: unique_bytes might not be accurate for the head objset.
1458 		 * Before SPA_VERSION 9, we didn't update its value when we
1459 		 * deleted the most recent snapshot.
1460 		 */
1461 		ASSERT3U(used, ==, ds->ds_phys->ds_unique_bytes);
1462 	} else {
1463 		/*
1464 		 * There's no next snapshot, so this is a head dataset.
1465 		 * Destroy the deadlist.  Unless it's a clone, the
1466 		 * deadlist should be empty.  (If it's a clone, it's
1467 		 * safe to ignore the deadlist contents.)
1468 		 */
1469 		struct killarg ka;
1470 
1471 		ASSERT(after_branch_point || bplist_empty(&ds->ds_deadlist));
1472 		bplist_close(&ds->ds_deadlist);
1473 		bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
1474 		ds->ds_phys->ds_deadlist_obj = 0;
1475 
1476 		/*
1477 		 * Free everything that we point to (that's born after
1478 		 * the previous snapshot, if we are a clone)
1479 		 *
1480 		 * XXX we're doing this long task with the config lock held
1481 		 */
1482 		ka.usedp = &used;
1483 		ka.compressedp = &compressed;
1484 		ka.uncompressedp = &uncompressed;
1485 		ka.zio = zio;
1486 		ka.tx = tx;
1487 		err = traverse_dsl_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
1488 		    ADVANCE_POST, kill_blkptr, &ka);
1489 		ASSERT3U(err, ==, 0);
1490 		ASSERT(spa_version(dp->dp_spa) <
1491 		    SPA_VERSION_UNIQUE_ACCURATE ||
1492 		    used == ds->ds_phys->ds_unique_bytes);
1493 	}
1494 
1495 	err = zio_wait(zio);
1496 	ASSERT3U(err, ==, 0);
1497 
1498 	dsl_dir_diduse_space(ds->ds_dir, -used, -compressed, -uncompressed, tx);
1499 
1500 	if (ds->ds_phys->ds_snapnames_zapobj) {
1501 		err = zap_destroy(mos, ds->ds_phys->ds_snapnames_zapobj, tx);
1502 		ASSERT(err == 0);
1503 	}
1504 
1505 	if (ds->ds_dir->dd_phys->dd_head_dataset_obj == ds->ds_object) {
1506 		/* Erase the link in the dataset */
1507 		dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
1508 		ds->ds_dir->dd_phys->dd_head_dataset_obj = 0;
1509 		/*
1510 		 * dsl_dir_sync_destroy() called us, they'll destroy
1511 		 * the dataset.
1512 		 */
1513 	} else {
1514 		/* remove from snapshot namespace */
1515 		dsl_dataset_t *ds_head;
1516 		VERIFY(0 == dsl_dataset_open_obj(dp,
1517 		    ds->ds_dir->dd_phys->dd_head_dataset_obj, NULL,
1518 		    DS_MODE_NONE, FTAG, &ds_head));
1519 		VERIFY(0 == dsl_dataset_get_snapname(ds));
1520 #ifdef ZFS_DEBUG
1521 		{
1522 			uint64_t val;
1523 			err = zap_lookup(mos,
1524 			    ds_head->ds_phys->ds_snapnames_zapobj,
1525 			    ds->ds_snapname, 8, 1, &val);
1526 			ASSERT3U(err, ==, 0);
1527 			ASSERT3U(val, ==, obj);
1528 		}
1529 #endif
1530 		err = zap_remove(mos, ds_head->ds_phys->ds_snapnames_zapobj,
1531 		    ds->ds_snapname, tx);
1532 		ASSERT(err == 0);
1533 		dsl_dataset_close(ds_head, DS_MODE_NONE, FTAG);
1534 	}
1535 
1536 	if (ds_prev && ds->ds_prev != ds_prev)
1537 		dsl_dataset_close(ds_prev, DS_MODE_NONE, FTAG);
1538 
1539 	spa_prop_clear_bootfs(dp->dp_spa, ds->ds_object, tx);
1540 	spa_history_internal_log(LOG_DS_DESTROY, dp->dp_spa, tx,
1541 	    cr, "dataset = %llu", ds->ds_object);
1542 
1543 	dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, tag);
1544 	VERIFY(0 == dmu_object_free(mos, obj, tx));
1545 
1546 }
1547 
1548 static int
1549 dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
1550 {
1551 	uint64_t asize;
1552 
1553 	if (!dmu_tx_is_syncing(tx))
1554 		return (0);
1555 
1556 	/*
1557 	 * If there's an fs-only reservation, any blocks that might become
1558 	 * owned by the snapshot dataset must be accommodated by space
1559 	 * outside of the reservation.
1560 	 */
1561 	asize = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
1562 	if (asize > dsl_dir_space_available(ds->ds_dir, NULL, 0, FALSE))
1563 		return (ENOSPC);
1564 
1565 	/*
1566 	 * Propogate any reserved space for this snapshot to other
1567 	 * snapshot checks in this sync group.
1568 	 */
1569 	if (asize > 0)
1570 		dsl_dir_willuse_space(ds->ds_dir, asize, tx);
1571 
1572 	return (0);
1573 }
1574 
1575 /* ARGSUSED */
1576 int
1577 dsl_dataset_snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
1578 {
1579 	dsl_dataset_t *ds = arg1;
1580 	const char *snapname = arg2;
1581 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
1582 	int err;
1583 	uint64_t value;
1584 
1585 	/*
1586 	 * We don't allow multiple snapshots of the same txg.  If there
1587 	 * is already one, try again.
1588 	 */
1589 	if (ds->ds_phys->ds_prev_snap_txg >= tx->tx_txg)
1590 		return (EAGAIN);
1591 
1592 	/*
1593 	 * Check for conflicting name snapshot name.
1594 	 */
1595 	err = zap_lookup(mos, ds->ds_phys->ds_snapnames_zapobj,
1596 	    snapname, 8, 1, &value);
1597 	if (err == 0)
1598 		return (EEXIST);
1599 	if (err != ENOENT)
1600 		return (err);
1601 
1602 	/*
1603 	 * Check that the dataset's name is not too long.  Name consists
1604 	 * of the dataset's length + 1 for the @-sign + snapshot name's length
1605 	 */
1606 	if (dsl_dataset_namelen(ds) + 1 + strlen(snapname) >= MAXNAMELEN)
1607 		return (ENAMETOOLONG);
1608 
1609 	err = dsl_dataset_snapshot_reserve_space(ds, tx);
1610 	if (err)
1611 		return (err);
1612 
1613 	ds->ds_trysnap_txg = tx->tx_txg;
1614 	return (0);
1615 }
1616 
1617 void
1618 dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1619 {
1620 	dsl_dataset_t *ds = arg1;
1621 	const char *snapname = arg2;
1622 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1623 	dmu_buf_t *dbuf;
1624 	dsl_dataset_phys_t *dsphys;
1625 	uint64_t dsobj;
1626 	objset_t *mos = dp->dp_meta_objset;
1627 	int err;
1628 
1629 	spa_scrub_restart(dp->dp_spa, tx->tx_txg);
1630 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
1631 
1632 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
1633 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
1634 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
1635 	dmu_buf_will_dirty(dbuf, tx);
1636 	dsphys = dbuf->db_data;
1637 	dsphys->ds_dir_obj = ds->ds_dir->dd_object;
1638 	dsphys->ds_fsid_guid = unique_create();
1639 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
1640 	    sizeof (dsphys->ds_guid));
1641 	dsphys->ds_prev_snap_obj = ds->ds_phys->ds_prev_snap_obj;
1642 	dsphys->ds_prev_snap_txg = ds->ds_phys->ds_prev_snap_txg;
1643 	dsphys->ds_next_snap_obj = ds->ds_object;
1644 	dsphys->ds_num_children = 1;
1645 	dsphys->ds_creation_time = gethrestime_sec();
1646 	dsphys->ds_creation_txg = tx->tx_txg;
1647 	dsphys->ds_deadlist_obj = ds->ds_phys->ds_deadlist_obj;
1648 	dsphys->ds_used_bytes = ds->ds_phys->ds_used_bytes;
1649 	dsphys->ds_compressed_bytes = ds->ds_phys->ds_compressed_bytes;
1650 	dsphys->ds_uncompressed_bytes = ds->ds_phys->ds_uncompressed_bytes;
1651 	dsphys->ds_flags = ds->ds_phys->ds_flags;
1652 	dsphys->ds_bp = ds->ds_phys->ds_bp;
1653 	dmu_buf_rele(dbuf, FTAG);
1654 
1655 	ASSERT3U(ds->ds_prev != 0, ==, ds->ds_phys->ds_prev_snap_obj != 0);
1656 	if (ds->ds_prev) {
1657 		ASSERT(ds->ds_prev->ds_phys->ds_next_snap_obj ==
1658 		    ds->ds_object ||
1659 		    ds->ds_prev->ds_phys->ds_num_children > 1);
1660 		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
1661 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
1662 			ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
1663 			    ds->ds_prev->ds_phys->ds_creation_txg);
1664 			ds->ds_prev->ds_phys->ds_next_snap_obj = dsobj;
1665 		}
1666 	}
1667 
1668 	/*
1669 	 * If we have a reference-reservation on this dataset, we will
1670 	 * need to increase the amount of refreservation being charged
1671 	 * since our unique space is going to zero.
1672 	 */
1673 	if (ds->ds_reserved) {
1674 		int64_t add = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
1675 		dsl_dir_diduse_space(ds->ds_dir, add, 0, 0, tx);
1676 	}
1677 
1678 	bplist_close(&ds->ds_deadlist);
1679 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1680 	ASSERT3U(ds->ds_phys->ds_prev_snap_txg, <, tx->tx_txg);
1681 	ds->ds_phys->ds_prev_snap_obj = dsobj;
1682 	ds->ds_phys->ds_prev_snap_txg = tx->tx_txg;
1683 	ds->ds_phys->ds_unique_bytes = 0;
1684 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
1685 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
1686 	ds->ds_phys->ds_deadlist_obj =
1687 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
1688 	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
1689 	    ds->ds_phys->ds_deadlist_obj));
1690 
1691 	dprintf("snap '%s' -> obj %llu\n", snapname, dsobj);
1692 	err = zap_add(mos, ds->ds_phys->ds_snapnames_zapobj,
1693 	    snapname, 8, 1, &dsobj, tx);
1694 	ASSERT(err == 0);
1695 
1696 	if (ds->ds_prev)
1697 		dsl_dataset_close(ds->ds_prev, DS_MODE_NONE, ds);
1698 	VERIFY(0 == dsl_dataset_open_obj(dp,
1699 	    ds->ds_phys->ds_prev_snap_obj, snapname,
1700 	    DS_MODE_NONE, ds, &ds->ds_prev));
1701 
1702 	spa_history_internal_log(LOG_DS_SNAPSHOT, dp->dp_spa, tx, cr,
1703 	    "dataset = %llu", dsobj);
1704 }
1705 
1706 void
1707 dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
1708 {
1709 	ASSERT(dmu_tx_is_syncing(tx));
1710 	ASSERT(ds->ds_user_ptr != NULL);
1711 	ASSERT(ds->ds_phys->ds_next_snap_obj == 0);
1712 
1713 	/*
1714 	 * in case we had to change ds_fsid_guid when we opened it,
1715 	 * sync it out now.
1716 	 */
1717 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1718 	ds->ds_phys->ds_fsid_guid = ds->ds_fsid_guid;
1719 
1720 	dsl_dir_dirty(ds->ds_dir, tx);
1721 	dmu_objset_sync(ds->ds_user_ptr, zio, tx);
1722 }
1723 
1724 void
1725 dsl_dataset_stats(dsl_dataset_t *ds, nvlist_t *nv)
1726 {
1727 	uint64_t refd, avail, uobjs, aobjs;
1728 
1729 	dsl_dir_stats(ds->ds_dir, nv);
1730 
1731 	dsl_dataset_space(ds, &refd, &avail, &uobjs, &aobjs);
1732 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_AVAILABLE, avail);
1733 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFERENCED, refd);
1734 
1735 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATION,
1736 	    ds->ds_phys->ds_creation_time);
1737 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATETXG,
1738 	    ds->ds_phys->ds_creation_txg);
1739 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFQUOTA,
1740 	    ds->ds_quota);
1741 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFRESERVATION,
1742 	    ds->ds_reserved);
1743 
1744 	if (ds->ds_phys->ds_next_snap_obj) {
1745 		/*
1746 		 * This is a snapshot; override the dd's space used with
1747 		 * our unique space and compression ratio.
1748 		 */
1749 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
1750 		    ds->ds_phys->ds_unique_bytes);
1751 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
1752 		    ds->ds_phys->ds_compressed_bytes == 0 ? 100 :
1753 		    (ds->ds_phys->ds_uncompressed_bytes * 100 /
1754 		    ds->ds_phys->ds_compressed_bytes));
1755 	}
1756 }
1757 
1758 void
1759 dsl_dataset_fast_stat(dsl_dataset_t *ds, dmu_objset_stats_t *stat)
1760 {
1761 	stat->dds_creation_txg = ds->ds_phys->ds_creation_txg;
1762 	stat->dds_inconsistent = ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT;
1763 	stat->dds_guid = ds->ds_phys->ds_guid;
1764 	if (ds->ds_phys->ds_next_snap_obj) {
1765 		stat->dds_is_snapshot = B_TRUE;
1766 		stat->dds_num_clones = ds->ds_phys->ds_num_children - 1;
1767 	}
1768 
1769 	/* clone origin is really a dsl_dir thing... */
1770 	rw_enter(&ds->ds_dir->dd_pool->dp_config_rwlock, RW_READER);
1771 	if (ds->ds_dir->dd_phys->dd_origin_obj) {
1772 		dsl_dataset_t *ods;
1773 
1774 		VERIFY(0 == dsl_dataset_open_obj(ds->ds_dir->dd_pool,
1775 		    ds->ds_dir->dd_phys->dd_origin_obj,
1776 		    NULL, DS_MODE_NONE, FTAG, &ods));
1777 		dsl_dataset_name(ods, stat->dds_origin);
1778 		dsl_dataset_close(ods, DS_MODE_NONE, FTAG);
1779 	}
1780 	rw_exit(&ds->ds_dir->dd_pool->dp_config_rwlock);
1781 }
1782 
1783 uint64_t
1784 dsl_dataset_fsid_guid(dsl_dataset_t *ds)
1785 {
1786 	return (ds->ds_fsid_guid);
1787 }
1788 
1789 void
1790 dsl_dataset_space(dsl_dataset_t *ds,
1791     uint64_t *refdbytesp, uint64_t *availbytesp,
1792     uint64_t *usedobjsp, uint64_t *availobjsp)
1793 {
1794 	*refdbytesp = ds->ds_phys->ds_used_bytes;
1795 	*availbytesp = dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE);
1796 	if (ds->ds_reserved > ds->ds_phys->ds_unique_bytes)
1797 		*availbytesp += ds->ds_reserved - ds->ds_phys->ds_unique_bytes;
1798 	if (ds->ds_quota != 0) {
1799 		/*
1800 		 * Adjust available bytes according to refquota
1801 		 */
1802 		if (*refdbytesp < ds->ds_quota)
1803 			*availbytesp = MIN(*availbytesp,
1804 			    ds->ds_quota - *refdbytesp);
1805 		else
1806 			*availbytesp = 0;
1807 	}
1808 	*usedobjsp = ds->ds_phys->ds_bp.blk_fill;
1809 	*availobjsp = DN_MAX_OBJECT - *usedobjsp;
1810 }
1811 
1812 boolean_t
1813 dsl_dataset_modified_since_lastsnap(dsl_dataset_t *ds)
1814 {
1815 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1816 
1817 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
1818 	    dsl_pool_sync_context(dp));
1819 	if (ds->ds_prev == NULL)
1820 		return (B_FALSE);
1821 	if (ds->ds_phys->ds_bp.blk_birth >
1822 	    ds->ds_prev->ds_phys->ds_creation_txg)
1823 		return (B_TRUE);
1824 	return (B_FALSE);
1825 }
1826 
1827 /* ARGSUSED */
1828 static int
1829 dsl_dataset_snapshot_rename_check(void *arg1, void *arg2, dmu_tx_t *tx)
1830 {
1831 	dsl_dataset_t *ds = arg1;
1832 	char *newsnapname = arg2;
1833 	dsl_dir_t *dd = ds->ds_dir;
1834 	objset_t *mos = dd->dd_pool->dp_meta_objset;
1835 	dsl_dataset_t *hds;
1836 	uint64_t val;
1837 	int err;
1838 
1839 	err = dsl_dataset_open_obj(dd->dd_pool,
1840 	    dd->dd_phys->dd_head_dataset_obj, NULL, DS_MODE_NONE, FTAG, &hds);
1841 	if (err)
1842 		return (err);
1843 
1844 	/* new name better not be in use */
1845 	err = zap_lookup(mos, hds->ds_phys->ds_snapnames_zapobj,
1846 	    newsnapname, 8, 1, &val);
1847 	dsl_dataset_close(hds, DS_MODE_NONE, FTAG);
1848 
1849 	if (err == 0)
1850 		err = EEXIST;
1851 	else if (err == ENOENT)
1852 		err = 0;
1853 
1854 	/* dataset name + 1 for the "@" + the new snapshot name must fit */
1855 	if (dsl_dir_namelen(ds->ds_dir) + 1 + strlen(newsnapname) >= MAXNAMELEN)
1856 		err = ENAMETOOLONG;
1857 
1858 	return (err);
1859 }
1860 
1861 static void
1862 dsl_dataset_snapshot_rename_sync(void *arg1, void *arg2,
1863     cred_t *cr, dmu_tx_t *tx)
1864 {
1865 	dsl_dataset_t *ds = arg1;
1866 	const char *newsnapname = arg2;
1867 	dsl_dir_t *dd = ds->ds_dir;
1868 	objset_t *mos = dd->dd_pool->dp_meta_objset;
1869 	dsl_dataset_t *hds;
1870 	int err;
1871 
1872 	ASSERT(ds->ds_phys->ds_next_snap_obj != 0);
1873 
1874 	VERIFY(0 == dsl_dataset_open_obj(dd->dd_pool,
1875 	    dd->dd_phys->dd_head_dataset_obj, NULL, DS_MODE_NONE, FTAG, &hds));
1876 
1877 	VERIFY(0 == dsl_dataset_get_snapname(ds));
1878 	err = zap_remove(mos, hds->ds_phys->ds_snapnames_zapobj,
1879 	    ds->ds_snapname, tx);
1880 	ASSERT3U(err, ==, 0);
1881 	mutex_enter(&ds->ds_lock);
1882 	(void) strcpy(ds->ds_snapname, newsnapname);
1883 	mutex_exit(&ds->ds_lock);
1884 	err = zap_add(mos, hds->ds_phys->ds_snapnames_zapobj,
1885 	    ds->ds_snapname, 8, 1, &ds->ds_object, tx);
1886 	ASSERT3U(err, ==, 0);
1887 
1888 	spa_history_internal_log(LOG_DS_RENAME, dd->dd_pool->dp_spa, tx,
1889 	    cr, "dataset = %llu", ds->ds_object);
1890 	dsl_dataset_close(hds, DS_MODE_NONE, FTAG);
1891 }
1892 
1893 struct renamesnaparg {
1894 	dsl_sync_task_group_t *dstg;
1895 	char failed[MAXPATHLEN];
1896 	char *oldsnap;
1897 	char *newsnap;
1898 };
1899 
1900 static int
1901 dsl_snapshot_rename_one(char *name, void *arg)
1902 {
1903 	struct renamesnaparg *ra = arg;
1904 	dsl_dataset_t *ds = NULL;
1905 	char *cp;
1906 	int err;
1907 
1908 	cp = name + strlen(name);
1909 	*cp = '@';
1910 	(void) strcpy(cp + 1, ra->oldsnap);
1911 
1912 	/*
1913 	 * For recursive snapshot renames the parent won't be changing
1914 	 * so we just pass name for both the to/from argument.
1915 	 */
1916 	if (err = zfs_secpolicy_rename_perms(name, name, CRED())) {
1917 		(void) strcpy(ra->failed, name);
1918 		return (err);
1919 	}
1920 
1921 	err = dsl_dataset_open(name, DS_MODE_READONLY | DS_MODE_STANDARD,
1922 	    ra->dstg, &ds);
1923 	if (err == ENOENT) {
1924 		*cp = '\0';
1925 		return (0);
1926 	}
1927 	if (err) {
1928 		(void) strcpy(ra->failed, name);
1929 		*cp = '\0';
1930 		dsl_dataset_close(ds, DS_MODE_STANDARD, ra->dstg);
1931 		return (err);
1932 	}
1933 
1934 #ifdef _KERNEL
1935 	/* for all filesystems undergoing rename, we'll need to unmount it */
1936 	(void) zfs_unmount_snap(name, NULL);
1937 #endif
1938 
1939 	*cp = '\0';
1940 
1941 	dsl_sync_task_create(ra->dstg, dsl_dataset_snapshot_rename_check,
1942 	    dsl_dataset_snapshot_rename_sync, ds, ra->newsnap, 0);
1943 
1944 	return (0);
1945 }
1946 
1947 static int
1948 dsl_recursive_rename(char *oldname, const char *newname)
1949 {
1950 	int err;
1951 	struct renamesnaparg *ra;
1952 	dsl_sync_task_t *dst;
1953 	spa_t *spa;
1954 	char *cp, *fsname = spa_strdup(oldname);
1955 	int len = strlen(oldname);
1956 
1957 	/* truncate the snapshot name to get the fsname */
1958 	cp = strchr(fsname, '@');
1959 	*cp = '\0';
1960 
1961 	err = spa_open(fsname, &spa, FTAG);
1962 	if (err) {
1963 		kmem_free(fsname, len + 1);
1964 		return (err);
1965 	}
1966 	ra = kmem_alloc(sizeof (struct renamesnaparg), KM_SLEEP);
1967 	ra->dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
1968 
1969 	ra->oldsnap = strchr(oldname, '@') + 1;
1970 	ra->newsnap = strchr(newname, '@') + 1;
1971 	*ra->failed = '\0';
1972 
1973 	err = dmu_objset_find(fsname, dsl_snapshot_rename_one, ra,
1974 	    DS_FIND_CHILDREN);
1975 	kmem_free(fsname, len + 1);
1976 
1977 	if (err == 0) {
1978 		err = dsl_sync_task_group_wait(ra->dstg);
1979 	}
1980 
1981 	for (dst = list_head(&ra->dstg->dstg_tasks); dst;
1982 	    dst = list_next(&ra->dstg->dstg_tasks, dst)) {
1983 		dsl_dataset_t *ds = dst->dst_arg1;
1984 		if (dst->dst_err) {
1985 			dsl_dir_name(ds->ds_dir, ra->failed);
1986 			(void) strcat(ra->failed, "@");
1987 			(void) strcat(ra->failed, ra->newsnap);
1988 		}
1989 		dsl_dataset_close(ds, DS_MODE_STANDARD, ra->dstg);
1990 	}
1991 
1992 	if (err)
1993 		(void) strcpy(oldname, ra->failed);
1994 
1995 	dsl_sync_task_group_destroy(ra->dstg);
1996 	kmem_free(ra, sizeof (struct renamesnaparg));
1997 	spa_close(spa, FTAG);
1998 	return (err);
1999 }
2000 
2001 static int
2002 dsl_valid_rename(char *oldname, void *arg)
2003 {
2004 	int delta = *(int *)arg;
2005 
2006 	if (strlen(oldname) + delta >= MAXNAMELEN)
2007 		return (ENAMETOOLONG);
2008 
2009 	return (0);
2010 }
2011 
2012 #pragma weak dmu_objset_rename = dsl_dataset_rename
2013 int
2014 dsl_dataset_rename(char *oldname, const char *newname,
2015     boolean_t recursive)
2016 {
2017 	dsl_dir_t *dd;
2018 	dsl_dataset_t *ds;
2019 	const char *tail;
2020 	int err;
2021 
2022 	err = dsl_dir_open(oldname, FTAG, &dd, &tail);
2023 	if (err)
2024 		return (err);
2025 	if (tail == NULL) {
2026 		int delta = strlen(newname) - strlen(oldname);
2027 
2028 		/* if we're growing, validate child size lengths */
2029 		if (delta > 0)
2030 			err = dmu_objset_find(oldname, dsl_valid_rename,
2031 			    &delta, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
2032 
2033 		if (!err)
2034 			err = dsl_dir_rename(dd, newname);
2035 		dsl_dir_close(dd, FTAG);
2036 		return (err);
2037 	}
2038 	if (tail[0] != '@') {
2039 		/* the name ended in a nonexistant component */
2040 		dsl_dir_close(dd, FTAG);
2041 		return (ENOENT);
2042 	}
2043 
2044 	dsl_dir_close(dd, FTAG);
2045 
2046 	/* new name must be snapshot in same filesystem */
2047 	tail = strchr(newname, '@');
2048 	if (tail == NULL)
2049 		return (EINVAL);
2050 	tail++;
2051 	if (strncmp(oldname, newname, tail - newname) != 0)
2052 		return (EXDEV);
2053 
2054 	if (recursive) {
2055 		err = dsl_recursive_rename(oldname, newname);
2056 	} else {
2057 		err = dsl_dataset_open(oldname,
2058 		    DS_MODE_READONLY | DS_MODE_STANDARD, FTAG, &ds);
2059 		if (err)
2060 			return (err);
2061 
2062 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2063 		    dsl_dataset_snapshot_rename_check,
2064 		    dsl_dataset_snapshot_rename_sync, ds, (char *)tail, 1);
2065 
2066 		dsl_dataset_close(ds, DS_MODE_STANDARD, FTAG);
2067 	}
2068 
2069 	return (err);
2070 }
2071 
2072 struct promotearg {
2073 	uint64_t used, comp, uncomp, unique;
2074 	uint64_t newnext_obj, snapnames_obj;
2075 };
2076 
2077 /* ARGSUSED */
2078 static int
2079 dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
2080 {
2081 	dsl_dataset_t *hds = arg1;
2082 	struct promotearg *pa = arg2;
2083 	dsl_dir_t *dd = hds->ds_dir;
2084 	dsl_pool_t *dp = hds->ds_dir->dd_pool;
2085 	dsl_dir_t *odd = NULL;
2086 	dsl_dataset_t *ds = NULL;
2087 	dsl_dataset_t *origin_ds = NULL;
2088 	dsl_dataset_t *newnext_ds = NULL;
2089 	int err;
2090 	char *name = NULL;
2091 	uint64_t itor = 0;
2092 	blkptr_t bp;
2093 
2094 	bzero(pa, sizeof (*pa));
2095 
2096 	/* Check that it is a clone */
2097 	if (dd->dd_phys->dd_origin_obj == 0)
2098 		return (EINVAL);
2099 
2100 	/* Since this is so expensive, don't do the preliminary check */
2101 	if (!dmu_tx_is_syncing(tx))
2102 		return (0);
2103 
2104 	if (err = dsl_dataset_open_obj(dp, dd->dd_phys->dd_origin_obj,
2105 	    NULL, DS_MODE_EXCLUSIVE, FTAG, &origin_ds))
2106 		goto out;
2107 	odd = origin_ds->ds_dir;
2108 
2109 	{
2110 		dsl_dataset_t *phds;
2111 		if (err = dsl_dataset_open_obj(dd->dd_pool,
2112 		    odd->dd_phys->dd_head_dataset_obj,
2113 		    NULL, DS_MODE_NONE, FTAG, &phds))
2114 			goto out;
2115 		pa->snapnames_obj = phds->ds_phys->ds_snapnames_zapobj;
2116 		dsl_dataset_close(phds, DS_MODE_NONE, FTAG);
2117 	}
2118 
2119 	if (hds->ds_phys->ds_flags & DS_FLAG_NOPROMOTE) {
2120 		err = EXDEV;
2121 		goto out;
2122 	}
2123 
2124 	/* find origin's new next ds */
2125 	VERIFY(0 == dsl_dataset_open_obj(dd->dd_pool, hds->ds_object,
2126 	    NULL, DS_MODE_NONE, FTAG, &newnext_ds));
2127 	while (newnext_ds->ds_phys->ds_prev_snap_obj != origin_ds->ds_object) {
2128 		dsl_dataset_t *prev;
2129 
2130 		if (err = dsl_dataset_open_obj(dd->dd_pool,
2131 		    newnext_ds->ds_phys->ds_prev_snap_obj,
2132 		    NULL, DS_MODE_NONE, FTAG, &prev))
2133 			goto out;
2134 		dsl_dataset_close(newnext_ds, DS_MODE_NONE, FTAG);
2135 		newnext_ds = prev;
2136 	}
2137 	pa->newnext_obj = newnext_ds->ds_object;
2138 
2139 	/* compute origin's new unique space */
2140 	while ((err = bplist_iterate(&newnext_ds->ds_deadlist,
2141 	    &itor, &bp)) == 0) {
2142 		if (bp.blk_birth > origin_ds->ds_phys->ds_prev_snap_txg)
2143 			pa->unique += bp_get_dasize(dd->dd_pool->dp_spa, &bp);
2144 	}
2145 	if (err != ENOENT)
2146 		goto out;
2147 
2148 	/* Walk the snapshots that we are moving */
2149 	name = kmem_alloc(MAXPATHLEN, KM_SLEEP);
2150 	ds = origin_ds;
2151 	/* CONSTCOND */
2152 	while (TRUE) {
2153 		uint64_t val, dlused, dlcomp, dluncomp;
2154 		dsl_dataset_t *prev;
2155 
2156 		/* Check that the snapshot name does not conflict */
2157 		dsl_dataset_name(ds, name);
2158 		err = zap_lookup(dd->dd_pool->dp_meta_objset,
2159 		    hds->ds_phys->ds_snapnames_zapobj, ds->ds_snapname,
2160 		    8, 1, &val);
2161 		if (err != ENOENT) {
2162 			if (err == 0)
2163 				err = EEXIST;
2164 			goto out;
2165 		}
2166 
2167 		/*
2168 		 * compute space to transfer.  Each snapshot gave birth to:
2169 		 * (my used) - (prev's used) + (deadlist's used)
2170 		 */
2171 		pa->used += ds->ds_phys->ds_used_bytes;
2172 		pa->comp += ds->ds_phys->ds_compressed_bytes;
2173 		pa->uncomp += ds->ds_phys->ds_uncompressed_bytes;
2174 
2175 		/* If we reach the first snapshot, we're done. */
2176 		if (ds->ds_phys->ds_prev_snap_obj == 0)
2177 			break;
2178 
2179 		if (err = bplist_space(&ds->ds_deadlist,
2180 		    &dlused, &dlcomp, &dluncomp))
2181 			goto out;
2182 		if (err = dsl_dataset_open_obj(dd->dd_pool,
2183 		    ds->ds_phys->ds_prev_snap_obj, NULL, DS_MODE_EXCLUSIVE,
2184 		    FTAG, &prev))
2185 			goto out;
2186 		pa->used += dlused - prev->ds_phys->ds_used_bytes;
2187 		pa->comp += dlcomp - prev->ds_phys->ds_compressed_bytes;
2188 		pa->uncomp += dluncomp - prev->ds_phys->ds_uncompressed_bytes;
2189 
2190 		/*
2191 		 * We could be a clone of a clone.  If we reach our
2192 		 * parent's branch point, we're done.
2193 		 */
2194 		if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
2195 			dsl_dataset_close(prev, DS_MODE_EXCLUSIVE, FTAG);
2196 			break;
2197 		}
2198 		if (ds != origin_ds)
2199 			dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2200 		ds = prev;
2201 	}
2202 
2203 	/* Check that there is enough space here */
2204 	err = dsl_dir_transfer_possible(odd, dd, pa->used);
2205 
2206 out:
2207 	if (ds && ds != origin_ds)
2208 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2209 	if (origin_ds)
2210 		dsl_dataset_close(origin_ds, DS_MODE_EXCLUSIVE, FTAG);
2211 	if (newnext_ds)
2212 		dsl_dataset_close(newnext_ds, DS_MODE_NONE, FTAG);
2213 	if (name)
2214 		kmem_free(name, MAXPATHLEN);
2215 	return (err);
2216 }
2217 
2218 static void
2219 dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
2220 {
2221 	dsl_dataset_t *hds = arg1;
2222 	struct promotearg *pa = arg2;
2223 	dsl_dir_t *dd = hds->ds_dir;
2224 	dsl_pool_t *dp = hds->ds_dir->dd_pool;
2225 	dsl_dir_t *odd = NULL;
2226 	dsl_dataset_t *ds, *origin_ds;
2227 	char *name;
2228 
2229 	ASSERT(dd->dd_phys->dd_origin_obj != 0);
2230 	ASSERT(0 == (hds->ds_phys->ds_flags & DS_FLAG_NOPROMOTE));
2231 
2232 	VERIFY(0 == dsl_dataset_open_obj(dp, dd->dd_phys->dd_origin_obj,
2233 	    NULL, DS_MODE_EXCLUSIVE, FTAG, &origin_ds));
2234 	/*
2235 	 * We need to explicitly open odd, since origin_ds's dd will be
2236 	 * changing.
2237 	 */
2238 	VERIFY(0 == dsl_dir_open_obj(dp, origin_ds->ds_dir->dd_object,
2239 	    NULL, FTAG, &odd));
2240 
2241 	/* move snapshots to this dir */
2242 	name = kmem_alloc(MAXPATHLEN, KM_SLEEP);
2243 	ds = origin_ds;
2244 	/* CONSTCOND */
2245 	while (TRUE) {
2246 		dsl_dataset_t *prev;
2247 
2248 		/* move snap name entry */
2249 		dsl_dataset_name(ds, name);
2250 		VERIFY(0 == zap_remove(dp->dp_meta_objset,
2251 		    pa->snapnames_obj, ds->ds_snapname, tx));
2252 		VERIFY(0 == zap_add(dp->dp_meta_objset,
2253 		    hds->ds_phys->ds_snapnames_zapobj, ds->ds_snapname,
2254 		    8, 1, &ds->ds_object, tx));
2255 
2256 		/* change containing dsl_dir */
2257 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
2258 		ASSERT3U(ds->ds_phys->ds_dir_obj, ==, odd->dd_object);
2259 		ds->ds_phys->ds_dir_obj = dd->dd_object;
2260 		ASSERT3P(ds->ds_dir, ==, odd);
2261 		dsl_dir_close(ds->ds_dir, ds);
2262 		VERIFY(0 == dsl_dir_open_obj(dp, dd->dd_object,
2263 		    NULL, ds, &ds->ds_dir));
2264 
2265 		ASSERT3U(dsl_prop_numcb(ds), ==, 0);
2266 
2267 		if (ds->ds_phys->ds_prev_snap_obj == 0)
2268 			break;
2269 
2270 		VERIFY(0 == dsl_dataset_open_obj(dp,
2271 		    ds->ds_phys->ds_prev_snap_obj, NULL, DS_MODE_EXCLUSIVE,
2272 		    FTAG, &prev));
2273 
2274 		if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
2275 			dsl_dataset_close(prev, DS_MODE_EXCLUSIVE, FTAG);
2276 			break;
2277 		}
2278 		if (ds != origin_ds)
2279 			dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2280 		ds = prev;
2281 	}
2282 	if (ds != origin_ds)
2283 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2284 
2285 	/* change origin's next snap */
2286 	dmu_buf_will_dirty(origin_ds->ds_dbuf, tx);
2287 	origin_ds->ds_phys->ds_next_snap_obj = pa->newnext_obj;
2288 
2289 	/* change origin */
2290 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
2291 	ASSERT3U(dd->dd_phys->dd_origin_obj, ==, origin_ds->ds_object);
2292 	dd->dd_phys->dd_origin_obj = odd->dd_phys->dd_origin_obj;
2293 	dmu_buf_will_dirty(odd->dd_dbuf, tx);
2294 	odd->dd_phys->dd_origin_obj = origin_ds->ds_object;
2295 
2296 	/* change space accounting */
2297 	dsl_dir_diduse_space(odd, -pa->used, -pa->comp, -pa->uncomp, tx);
2298 	dsl_dir_diduse_space(dd, pa->used, pa->comp, pa->uncomp, tx);
2299 	origin_ds->ds_phys->ds_unique_bytes = pa->unique;
2300 
2301 	/* log history record */
2302 	spa_history_internal_log(LOG_DS_PROMOTE, dd->dd_pool->dp_spa, tx,
2303 	    cr, "dataset = %llu", ds->ds_object);
2304 
2305 	dsl_dir_close(odd, FTAG);
2306 	dsl_dataset_close(origin_ds, DS_MODE_EXCLUSIVE, FTAG);
2307 	kmem_free(name, MAXPATHLEN);
2308 }
2309 
2310 int
2311 dsl_dataset_promote(const char *name)
2312 {
2313 	dsl_dataset_t *ds;
2314 	int err;
2315 	dmu_object_info_t doi;
2316 	struct promotearg pa;
2317 
2318 	err = dsl_dataset_open(name, DS_MODE_NONE, FTAG, &ds);
2319 	if (err)
2320 		return (err);
2321 
2322 	err = dmu_object_info(ds->ds_dir->dd_pool->dp_meta_objset,
2323 	    ds->ds_phys->ds_snapnames_zapobj, &doi);
2324 	if (err) {
2325 		dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
2326 		return (err);
2327 	}
2328 
2329 	/*
2330 	 * Add in 128x the snapnames zapobj size, since we will be moving
2331 	 * a bunch of snapnames to the promoted ds, and dirtying their
2332 	 * bonus buffers.
2333 	 */
2334 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2335 	    dsl_dataset_promote_check,
2336 	    dsl_dataset_promote_sync, ds, &pa, 2 + 2 * doi.doi_physical_blks);
2337 	dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
2338 	return (err);
2339 }
2340 
2341 struct cloneswaparg {
2342 	dsl_dataset_t *cds; /* clone dataset */
2343 	dsl_dataset_t *ohds; /* origin's head dataset */
2344 	boolean_t force;
2345 	int64_t unused_refres_delta; /* change in unconsumed refreservation */
2346 };
2347 
2348 /* ARGSUSED */
2349 static int
2350 dsl_dataset_clone_swap_check(void *arg1, void *arg2, dmu_tx_t *tx)
2351 {
2352 	struct cloneswaparg *csa = arg1;
2353 
2354 	/* they should both be heads */
2355 	if (dsl_dataset_is_snapshot(csa->cds) ||
2356 	    dsl_dataset_is_snapshot(csa->ohds))
2357 		return (EINVAL);
2358 
2359 	/* the branch point should be just before them */
2360 	if (csa->cds->ds_prev != csa->ohds->ds_prev)
2361 		return (EINVAL);
2362 
2363 	/* cds should be the clone */
2364 	if (csa->cds->ds_prev->ds_phys->ds_next_snap_obj !=
2365 	    csa->ohds->ds_object)
2366 		return (EINVAL);
2367 
2368 	/* the clone should be a child of the origin */
2369 	if (csa->cds->ds_dir->dd_parent != csa->ohds->ds_dir)
2370 		return (EINVAL);
2371 
2372 	/* ohds shouldn't be modified unless 'force' */
2373 	if (!csa->force && dsl_dataset_modified_since_lastsnap(csa->ohds))
2374 		return (ETXTBSY);
2375 
2376 	/* adjust amount of any unconsumed refreservation */
2377 	csa->unused_refres_delta =
2378 	    (int64_t)MIN(csa->ohds->ds_reserved,
2379 	    csa->ohds->ds_phys->ds_unique_bytes) -
2380 	    (int64_t)MIN(csa->ohds->ds_reserved,
2381 	    csa->cds->ds_phys->ds_unique_bytes);
2382 
2383 	if (csa->unused_refres_delta > 0 &&
2384 	    csa->unused_refres_delta >
2385 	    dsl_dir_space_available(csa->ohds->ds_dir, NULL, 0, TRUE))
2386 		return (ENOSPC);
2387 
2388 	return (0);
2389 }
2390 
2391 /* ARGSUSED */
2392 static void
2393 dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
2394 {
2395 	struct cloneswaparg *csa = arg1;
2396 	dsl_pool_t *dp = csa->cds->ds_dir->dd_pool;
2397 	uint64_t itor = 0;
2398 	blkptr_t bp;
2399 	uint64_t unique = 0;
2400 	int err;
2401 
2402 	ASSERT(csa->cds->ds_reserved == 0);
2403 	ASSERT(csa->cds->ds_quota == csa->ohds->ds_quota);
2404 
2405 	dmu_buf_will_dirty(csa->cds->ds_dbuf, tx);
2406 	dmu_buf_will_dirty(csa->ohds->ds_dbuf, tx);
2407 	dmu_buf_will_dirty(csa->cds->ds_prev->ds_dbuf, tx);
2408 
2409 	if (csa->cds->ds_user_ptr != NULL) {
2410 		csa->cds->ds_user_evict_func(csa->cds, csa->cds->ds_user_ptr);
2411 		csa->cds->ds_user_ptr = NULL;
2412 	}
2413 
2414 	if (csa->ohds->ds_user_ptr != NULL) {
2415 		csa->ohds->ds_user_evict_func(csa->ohds,
2416 		    csa->ohds->ds_user_ptr);
2417 		csa->ohds->ds_user_ptr = NULL;
2418 	}
2419 
2420 	/* compute unique space */
2421 	while ((err = bplist_iterate(&csa->cds->ds_deadlist,
2422 	    &itor, &bp)) == 0) {
2423 		if (bp.blk_birth > csa->cds->ds_prev->ds_phys->ds_prev_snap_txg)
2424 			unique += bp_get_dasize(dp->dp_spa, &bp);
2425 	}
2426 	VERIFY(err == ENOENT);
2427 
2428 	/* reset origin's unique bytes */
2429 	csa->cds->ds_prev->ds_phys->ds_unique_bytes = unique;
2430 
2431 	/* swap blkptrs */
2432 	{
2433 		blkptr_t tmp;
2434 		tmp = csa->ohds->ds_phys->ds_bp;
2435 		csa->ohds->ds_phys->ds_bp = csa->cds->ds_phys->ds_bp;
2436 		csa->cds->ds_phys->ds_bp = tmp;
2437 	}
2438 
2439 	/* set dd_*_bytes */
2440 	{
2441 		int64_t dused, dcomp, duncomp;
2442 		uint64_t cdl_used, cdl_comp, cdl_uncomp;
2443 		uint64_t odl_used, odl_comp, odl_uncomp;
2444 
2445 		VERIFY(0 == bplist_space(&csa->cds->ds_deadlist, &cdl_used,
2446 		    &cdl_comp, &cdl_uncomp));
2447 		VERIFY(0 == bplist_space(&csa->ohds->ds_deadlist, &odl_used,
2448 		    &odl_comp, &odl_uncomp));
2449 		dused = csa->cds->ds_phys->ds_used_bytes + cdl_used -
2450 		    (csa->ohds->ds_phys->ds_used_bytes + odl_used);
2451 		dcomp = csa->cds->ds_phys->ds_compressed_bytes + cdl_comp -
2452 		    (csa->ohds->ds_phys->ds_compressed_bytes + odl_comp);
2453 		duncomp = csa->cds->ds_phys->ds_uncompressed_bytes +
2454 		    cdl_uncomp -
2455 		    (csa->ohds->ds_phys->ds_uncompressed_bytes + odl_uncomp);
2456 
2457 		dsl_dir_diduse_space(csa->ohds->ds_dir,
2458 		    dused, dcomp, duncomp, tx);
2459 		dsl_dir_diduse_space(csa->cds->ds_dir,
2460 		    -dused, -dcomp, -duncomp, tx);
2461 	}
2462 
2463 #define	SWITCH64(x, y) \
2464 	{ \
2465 		uint64_t __tmp = (x); \
2466 		(x) = (y); \
2467 		(y) = __tmp; \
2468 	}
2469 
2470 	/* swap ds_*_bytes */
2471 	SWITCH64(csa->ohds->ds_phys->ds_used_bytes,
2472 	    csa->cds->ds_phys->ds_used_bytes);
2473 	SWITCH64(csa->ohds->ds_phys->ds_compressed_bytes,
2474 	    csa->cds->ds_phys->ds_compressed_bytes);
2475 	SWITCH64(csa->ohds->ds_phys->ds_uncompressed_bytes,
2476 	    csa->cds->ds_phys->ds_uncompressed_bytes);
2477 	SWITCH64(csa->ohds->ds_phys->ds_unique_bytes,
2478 	    csa->cds->ds_phys->ds_unique_bytes);
2479 
2480 	/* apply any parent delta for change in unconsumed refreservation */
2481 	dsl_dir_diduse_space(csa->ohds->ds_dir, csa->unused_refres_delta,
2482 	    0, 0, tx);
2483 
2484 	/* swap deadlists */
2485 	bplist_close(&csa->cds->ds_deadlist);
2486 	bplist_close(&csa->ohds->ds_deadlist);
2487 	SWITCH64(csa->ohds->ds_phys->ds_deadlist_obj,
2488 	    csa->cds->ds_phys->ds_deadlist_obj);
2489 	VERIFY(0 == bplist_open(&csa->cds->ds_deadlist, dp->dp_meta_objset,
2490 	    csa->cds->ds_phys->ds_deadlist_obj));
2491 	VERIFY(0 == bplist_open(&csa->ohds->ds_deadlist, dp->dp_meta_objset,
2492 	    csa->ohds->ds_phys->ds_deadlist_obj));
2493 }
2494 
2495 /*
2496  * Swap 'clone' with its origin head file system.
2497  */
2498 int
2499 dsl_dataset_clone_swap(dsl_dataset_t *clone, dsl_dataset_t *origin_head,
2500     boolean_t force)
2501 {
2502 	struct cloneswaparg csa;
2503 
2504 	ASSERT(clone->ds_open_refcount == DS_REF_MAX);
2505 	ASSERT(origin_head->ds_open_refcount == DS_REF_MAX);
2506 
2507 	csa.cds = clone;
2508 	csa.ohds = origin_head;
2509 	csa.force = force;
2510 	return (dsl_sync_task_do(clone->ds_dir->dd_pool,
2511 	    dsl_dataset_clone_swap_check,
2512 	    dsl_dataset_clone_swap_sync, &csa, NULL, 9));
2513 }
2514 
2515 /*
2516  * Given a pool name and a dataset object number in that pool,
2517  * return the name of that dataset.
2518  */
2519 int
2520 dsl_dsobj_to_dsname(char *pname, uint64_t obj, char *buf)
2521 {
2522 	spa_t *spa;
2523 	dsl_pool_t *dp;
2524 	dsl_dataset_t *ds = NULL;
2525 	int error;
2526 
2527 	if ((error = spa_open(pname, &spa, FTAG)) != 0)
2528 		return (error);
2529 	dp = spa_get_dsl(spa);
2530 	rw_enter(&dp->dp_config_rwlock, RW_READER);
2531 	if ((error = dsl_dataset_open_obj(dp, obj,
2532 	    NULL, DS_MODE_NONE, FTAG, &ds)) != 0) {
2533 		rw_exit(&dp->dp_config_rwlock);
2534 		spa_close(spa, FTAG);
2535 		return (error);
2536 	}
2537 	dsl_dataset_name(ds, buf);
2538 	dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
2539 	rw_exit(&dp->dp_config_rwlock);
2540 	spa_close(spa, FTAG);
2541 
2542 	return (0);
2543 }
2544 
2545 int
2546 dsl_dataset_check_quota(dsl_dataset_t *ds, boolean_t check_quota,
2547     uint64_t asize, uint64_t inflight, uint64_t *used)
2548 {
2549 	int error = 0;
2550 
2551 	ASSERT3S(asize, >, 0);
2552 
2553 	mutex_enter(&ds->ds_lock);
2554 	/*
2555 	 * Make a space adjustment for reserved bytes.
2556 	 */
2557 	if (ds->ds_reserved > ds->ds_phys->ds_unique_bytes) {
2558 		ASSERT3U(*used, >=,
2559 		    ds->ds_reserved - ds->ds_phys->ds_unique_bytes);
2560 		*used -= (ds->ds_reserved - ds->ds_phys->ds_unique_bytes);
2561 	}
2562 
2563 	if (!check_quota || ds->ds_quota == 0) {
2564 		mutex_exit(&ds->ds_lock);
2565 		return (0);
2566 	}
2567 	/*
2568 	 * If they are requesting more space, and our current estimate
2569 	 * is over quota, they get to try again unless the actual
2570 	 * on-disk is over quota and there are no pending changes (which
2571 	 * may free up space for us).
2572 	 */
2573 	if (ds->ds_phys->ds_used_bytes + inflight >= ds->ds_quota) {
2574 		if (inflight > 0 || ds->ds_phys->ds_used_bytes < ds->ds_quota)
2575 			error = ERESTART;
2576 		else
2577 			error = EDQUOT;
2578 	}
2579 	mutex_exit(&ds->ds_lock);
2580 
2581 	return (error);
2582 }
2583 
2584 /* ARGSUSED */
2585 static int
2586 dsl_dataset_set_quota_check(void *arg1, void *arg2, dmu_tx_t *tx)
2587 {
2588 	dsl_dataset_t *ds = arg1;
2589 	uint64_t *quotap = arg2;
2590 	uint64_t new_quota = *quotap;
2591 
2592 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) < SPA_VERSION_REFQUOTA)
2593 		return (ENOTSUP);
2594 
2595 	if (new_quota == 0)
2596 		return (0);
2597 
2598 	if (new_quota < ds->ds_phys->ds_used_bytes ||
2599 	    new_quota < ds->ds_reserved)
2600 		return (ENOSPC);
2601 
2602 	return (0);
2603 }
2604 
2605 /* ARGSUSED */
2606 void
2607 dsl_dataset_set_quota_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
2608 {
2609 	dsl_dataset_t *ds = arg1;
2610 	uint64_t *quotap = arg2;
2611 	uint64_t new_quota = *quotap;
2612 
2613 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
2614 
2615 	mutex_enter(&ds->ds_lock);
2616 	ds->ds_quota = new_quota;
2617 	mutex_exit(&ds->ds_lock);
2618 
2619 	dsl_prop_set_uint64_sync(ds->ds_dir, "refquota", new_quota, cr, tx);
2620 
2621 	spa_history_internal_log(LOG_DS_REFQUOTA, ds->ds_dir->dd_pool->dp_spa,
2622 	    tx, cr, "%lld dataset = %llu ",
2623 	    (longlong_t)new_quota, ds->ds_dir->dd_phys->dd_head_dataset_obj);
2624 }
2625 
2626 int
2627 dsl_dataset_set_quota(const char *dsname, uint64_t quota)
2628 {
2629 	dsl_dataset_t *ds;
2630 	int err;
2631 
2632 	err = dsl_dataset_open(dsname, DS_MODE_STANDARD, FTAG, &ds);
2633 	if (err)
2634 		return (err);
2635 
2636 	if (quota != ds->ds_quota) {
2637 		/*
2638 		 * If someone removes a file, then tries to set the quota, we
2639 		 * want to make sure the file freeing takes effect.
2640 		 */
2641 		txg_wait_open(ds->ds_dir->dd_pool, 0);
2642 
2643 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2644 		    dsl_dataset_set_quota_check, dsl_dataset_set_quota_sync,
2645 		    ds, &quota, 0);
2646 	}
2647 	dsl_dataset_close(ds, DS_MODE_STANDARD, FTAG);
2648 	return (err);
2649 }
2650 
2651 static int
2652 dsl_dataset_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
2653 {
2654 	dsl_dataset_t *ds = arg1;
2655 	uint64_t *reservationp = arg2;
2656 	uint64_t new_reservation = *reservationp;
2657 	int64_t delta;
2658 	uint64_t unique;
2659 
2660 	if (new_reservation > INT64_MAX)
2661 		return (EOVERFLOW);
2662 
2663 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) <
2664 	    SPA_VERSION_REFRESERVATION)
2665 		return (ENOTSUP);
2666 
2667 	if (dsl_dataset_is_snapshot(ds))
2668 		return (EINVAL);
2669 
2670 	/*
2671 	 * If we are doing the preliminary check in open context, the
2672 	 * space estimates may be inaccurate.
2673 	 */
2674 	if (!dmu_tx_is_syncing(tx))
2675 		return (0);
2676 
2677 	mutex_enter(&ds->ds_lock);
2678 	unique = dsl_dataset_unique(ds);
2679 	delta = MAX(unique, new_reservation) - MAX(unique, ds->ds_reserved);
2680 	mutex_exit(&ds->ds_lock);
2681 
2682 	if (delta > 0 &&
2683 	    delta > dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE))
2684 		return (ENOSPC);
2685 	if (delta > 0 && ds->ds_quota > 0 &&
2686 	    new_reservation > ds->ds_quota)
2687 		return (ENOSPC);
2688 
2689 	return (0);
2690 }
2691 
2692 /* ARGSUSED */
2693 static void
2694 dsl_dataset_set_reservation_sync(void *arg1, void *arg2, cred_t *cr,
2695     dmu_tx_t *tx)
2696 {
2697 	dsl_dataset_t *ds = arg1;
2698 	uint64_t *reservationp = arg2;
2699 	uint64_t new_reservation = *reservationp;
2700 	uint64_t unique;
2701 	int64_t delta;
2702 
2703 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
2704 
2705 	mutex_enter(&ds->ds_lock);
2706 	unique = dsl_dataset_unique(ds);
2707 	delta = MAX(0, (int64_t)(new_reservation - unique)) -
2708 	    MAX(0, (int64_t)(ds->ds_reserved - unique));
2709 	ds->ds_reserved = new_reservation;
2710 	mutex_exit(&ds->ds_lock);
2711 
2712 	dsl_prop_set_uint64_sync(ds->ds_dir, "refreservation",
2713 	    new_reservation, cr, tx);
2714 
2715 	dsl_dir_diduse_space(ds->ds_dir, delta, 0, 0, tx);
2716 
2717 	spa_history_internal_log(LOG_DS_REFRESERV,
2718 	    ds->ds_dir->dd_pool->dp_spa, tx, cr, "%lld dataset = %llu",
2719 	    (longlong_t)new_reservation,
2720 	    ds->ds_dir->dd_phys->dd_head_dataset_obj);
2721 }
2722 
2723 int
2724 dsl_dataset_set_reservation(const char *dsname, uint64_t reservation)
2725 {
2726 	dsl_dataset_t *ds;
2727 	int err;
2728 
2729 	err = dsl_dataset_open(dsname, DS_MODE_STANDARD, FTAG, &ds);
2730 	if (err)
2731 		return (err);
2732 
2733 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2734 	    dsl_dataset_set_reservation_check,
2735 	    dsl_dataset_set_reservation_sync, ds, &reservation, 0);
2736 	dsl_dataset_close(ds, DS_MODE_STANDARD, FTAG);
2737 	return (err);
2738 }
2739