xref: /illumos-gate/usr/src/uts/common/fs/zfs/dsl_dataset.c (revision a9b821a05317e0a13944933cac8976e203c08991)
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 		/* if (bp->blk_birth > prev prev snap txg) prev unique += bs */
183 		if (ds->ds_phys->ds_prev_snap_obj != 0) {
184 			ASSERT3U(ds->ds_prev->ds_object, ==,
185 			    ds->ds_phys->ds_prev_snap_obj);
186 			ASSERT(ds->ds_prev->ds_phys->ds_num_children > 0);
187 			if (ds->ds_prev->ds_phys->ds_next_snap_obj ==
188 			    ds->ds_object && bp->blk_birth >
189 			    ds->ds_prev->ds_phys->ds_prev_snap_txg) {
190 				dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
191 				mutex_enter(&ds->ds_prev->ds_lock);
192 				ds->ds_prev->ds_phys->ds_unique_bytes +=
193 				    used;
194 				mutex_exit(&ds->ds_prev->ds_lock);
195 			}
196 		}
197 	}
198 	mutex_enter(&ds->ds_lock);
199 	ASSERT3U(ds->ds_phys->ds_used_bytes, >=, used);
200 	ds->ds_phys->ds_used_bytes -= used;
201 	ASSERT3U(ds->ds_phys->ds_compressed_bytes, >=, compressed);
202 	ds->ds_phys->ds_compressed_bytes -= compressed;
203 	ASSERT3U(ds->ds_phys->ds_uncompressed_bytes, >=, uncompressed);
204 	ds->ds_phys->ds_uncompressed_bytes -= uncompressed;
205 	mutex_exit(&ds->ds_lock);
206 }
207 
208 uint64_t
209 dsl_dataset_prev_snap_txg(dsl_dataset_t *ds)
210 {
211 	uint64_t trysnap = 0;
212 
213 	if (ds == NULL)
214 		return (0);
215 	/*
216 	 * The snapshot creation could fail, but that would cause an
217 	 * incorrect FALSE return, which would only result in an
218 	 * overestimation of the amount of space that an operation would
219 	 * consume, which is OK.
220 	 *
221 	 * There's also a small window where we could miss a pending
222 	 * snapshot, because we could set the sync task in the quiescing
223 	 * phase.  So this should only be used as a guess.
224 	 */
225 	if (ds->ds_trysnap_txg >
226 	    spa_last_synced_txg(ds->ds_dir->dd_pool->dp_spa))
227 		trysnap = ds->ds_trysnap_txg;
228 	return (MAX(ds->ds_phys->ds_prev_snap_txg, trysnap));
229 }
230 
231 int
232 dsl_dataset_block_freeable(dsl_dataset_t *ds, uint64_t blk_birth)
233 {
234 	return (blk_birth > dsl_dataset_prev_snap_txg(ds));
235 }
236 
237 /* ARGSUSED */
238 static void
239 dsl_dataset_evict(dmu_buf_t *db, void *dsv)
240 {
241 	dsl_dataset_t *ds = dsv;
242 
243 	/* open_refcount == DS_REF_MAX when deleting */
244 	ASSERT(ds->ds_open_refcount == 0 ||
245 	    ds->ds_open_refcount == DS_REF_MAX);
246 
247 	dprintf_ds(ds, "evicting %s\n", "");
248 
249 	unique_remove(ds->ds_fsid_guid);
250 
251 	if (ds->ds_user_ptr != NULL)
252 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
253 
254 	if (ds->ds_prev) {
255 		dsl_dataset_close(ds->ds_prev, DS_MODE_NONE, ds);
256 		ds->ds_prev = NULL;
257 	}
258 
259 	bplist_close(&ds->ds_deadlist);
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 
268 	kmem_free(ds, sizeof (dsl_dataset_t));
269 }
270 
271 static int
272 dsl_dataset_get_snapname(dsl_dataset_t *ds)
273 {
274 	dsl_dataset_phys_t *headphys;
275 	int err;
276 	dmu_buf_t *headdbuf;
277 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
278 	objset_t *mos = dp->dp_meta_objset;
279 
280 	if (ds->ds_snapname[0])
281 		return (0);
282 	if (ds->ds_phys->ds_next_snap_obj == 0)
283 		return (0);
284 
285 	err = dmu_bonus_hold(mos, ds->ds_dir->dd_phys->dd_head_dataset_obj,
286 	    FTAG, &headdbuf);
287 	if (err)
288 		return (err);
289 	headphys = headdbuf->db_data;
290 	err = zap_value_search(dp->dp_meta_objset,
291 	    headphys->ds_snapnames_zapobj, ds->ds_object, 0, ds->ds_snapname);
292 	dmu_buf_rele(headdbuf, FTAG);
293 	return (err);
294 }
295 
296 int
297 dsl_dataset_open_obj(dsl_pool_t *dp, uint64_t dsobj, const char *snapname,
298     int mode, void *tag, dsl_dataset_t **dsp)
299 {
300 	uint64_t weight = ds_refcnt_weight[DS_MODE_LEVEL(mode)];
301 	objset_t *mos = dp->dp_meta_objset;
302 	dmu_buf_t *dbuf;
303 	dsl_dataset_t *ds;
304 	int err;
305 
306 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
307 	    dsl_pool_sync_context(dp));
308 
309 	err = dmu_bonus_hold(mos, dsobj, tag, &dbuf);
310 	if (err)
311 		return (err);
312 	ds = dmu_buf_get_user(dbuf);
313 	if (ds == NULL) {
314 		dsl_dataset_t *winner;
315 
316 		ds = kmem_zalloc(sizeof (dsl_dataset_t), KM_SLEEP);
317 		ds->ds_dbuf = dbuf;
318 		ds->ds_object = dsobj;
319 		ds->ds_phys = dbuf->db_data;
320 
321 		mutex_init(&ds->ds_lock, NULL, MUTEX_DEFAULT, NULL);
322 		mutex_init(&ds->ds_opening_lock, NULL, MUTEX_DEFAULT, NULL);
323 		mutex_init(&ds->ds_deadlist.bpl_lock, NULL, MUTEX_DEFAULT,
324 		    NULL);
325 
326 		err = bplist_open(&ds->ds_deadlist,
327 		    mos, ds->ds_phys->ds_deadlist_obj);
328 		if (err == 0) {
329 			err = dsl_dir_open_obj(dp,
330 			    ds->ds_phys->ds_dir_obj, NULL, ds, &ds->ds_dir);
331 		}
332 		if (err) {
333 			/*
334 			 * we don't really need to close the blist if we
335 			 * just opened it.
336 			 */
337 			mutex_destroy(&ds->ds_lock);
338 			mutex_destroy(&ds->ds_opening_lock);
339 			mutex_destroy(&ds->ds_deadlist.bpl_lock);
340 			kmem_free(ds, sizeof (dsl_dataset_t));
341 			dmu_buf_rele(dbuf, tag);
342 			return (err);
343 		}
344 
345 		if (ds->ds_dir->dd_phys->dd_head_dataset_obj == dsobj) {
346 			ds->ds_snapname[0] = '\0';
347 			if (ds->ds_phys->ds_prev_snap_obj) {
348 				err = dsl_dataset_open_obj(dp,
349 				    ds->ds_phys->ds_prev_snap_obj, NULL,
350 				    DS_MODE_NONE, ds, &ds->ds_prev);
351 			}
352 		} else {
353 			if (snapname) {
354 #ifdef ZFS_DEBUG
355 				dsl_dataset_phys_t *headphys;
356 				dmu_buf_t *headdbuf;
357 				err = dmu_bonus_hold(mos,
358 				    ds->ds_dir->dd_phys->dd_head_dataset_obj,
359 				    FTAG, &headdbuf);
360 				if (err == 0) {
361 					headphys = headdbuf->db_data;
362 					uint64_t foundobj;
363 					err = zap_lookup(dp->dp_meta_objset,
364 					    headphys->ds_snapnames_zapobj,
365 					    snapname, sizeof (foundobj), 1,
366 					    &foundobj);
367 					ASSERT3U(foundobj, ==, dsobj);
368 					dmu_buf_rele(headdbuf, FTAG);
369 				}
370 #endif
371 				(void) strcat(ds->ds_snapname, snapname);
372 			} else if (zfs_flags & ZFS_DEBUG_SNAPNAMES) {
373 				err = dsl_dataset_get_snapname(ds);
374 			}
375 		}
376 
377 		if (!dsl_dataset_is_snapshot(ds)) {
378 			boolean_t need_lock =
379 			    !RW_LOCK_HELD(&dp->dp_config_rwlock);
380 
381 			if (need_lock)
382 				rw_enter(&dp->dp_config_rwlock, RW_READER);
383 
384 			err = dsl_prop_get_ds_locked(ds->ds_dir,
385 			    "refreservation", sizeof (uint64_t), 1,
386 			    &ds->ds_reserved, NULL);
387 			if (err == 0) {
388 				err = dsl_prop_get_ds_locked(ds->ds_dir,
389 				    "refquota", sizeof (uint64_t), 1,
390 				    &ds->ds_quota, NULL);
391 			}
392 
393 			if (need_lock)
394 				rw_exit(&dp->dp_config_rwlock);
395 		} else {
396 			ds->ds_reserved = ds->ds_quota = 0;
397 		}
398 
399 		if (err == 0) {
400 			winner = dmu_buf_set_user_ie(dbuf, ds, &ds->ds_phys,
401 			    dsl_dataset_evict);
402 		}
403 		if (err || winner) {
404 			bplist_close(&ds->ds_deadlist);
405 			if (ds->ds_prev) {
406 				dsl_dataset_close(ds->ds_prev,
407 				    DS_MODE_NONE, ds);
408 			}
409 			dsl_dir_close(ds->ds_dir, ds);
410 			mutex_destroy(&ds->ds_lock);
411 			mutex_destroy(&ds->ds_opening_lock);
412 			mutex_destroy(&ds->ds_deadlist.bpl_lock);
413 			kmem_free(ds, sizeof (dsl_dataset_t));
414 			if (err) {
415 				dmu_buf_rele(dbuf, tag);
416 				return (err);
417 			}
418 			ds = winner;
419 		} else {
420 			ds->ds_fsid_guid =
421 			    unique_insert(ds->ds_phys->ds_fsid_guid);
422 		}
423 	}
424 	ASSERT3P(ds->ds_dbuf, ==, dbuf);
425 	ASSERT3P(ds->ds_phys, ==, dbuf->db_data);
426 
427 	mutex_enter(&ds->ds_lock);
428 	if ((DS_MODE_LEVEL(mode) == DS_MODE_PRIMARY &&
429 	    (ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT) &&
430 	    !DS_MODE_IS_INCONSISTENT(mode)) ||
431 	    (ds->ds_open_refcount + weight > DS_REF_MAX)) {
432 		mutex_exit(&ds->ds_lock);
433 		dsl_dataset_close(ds, DS_MODE_NONE, tag);
434 		return (EBUSY);
435 	}
436 	ds->ds_open_refcount += weight;
437 	mutex_exit(&ds->ds_lock);
438 
439 	*dsp = ds;
440 	return (0);
441 }
442 
443 int
444 dsl_dataset_open_spa(spa_t *spa, const char *name, int mode,
445     void *tag, dsl_dataset_t **dsp)
446 {
447 	dsl_dir_t *dd;
448 	dsl_pool_t *dp;
449 	const char *tail;
450 	uint64_t obj;
451 	dsl_dataset_t *ds = NULL;
452 	int err = 0;
453 
454 	err = dsl_dir_open_spa(spa, name, FTAG, &dd, &tail);
455 	if (err)
456 		return (err);
457 
458 	dp = dd->dd_pool;
459 	obj = dd->dd_phys->dd_head_dataset_obj;
460 	rw_enter(&dp->dp_config_rwlock, RW_READER);
461 	if (obj == 0) {
462 		/* A dataset with no associated objset */
463 		err = ENOENT;
464 		goto out;
465 	}
466 
467 	if (tail != NULL) {
468 		objset_t *mos = dp->dp_meta_objset;
469 
470 		err = dsl_dataset_open_obj(dp, obj, NULL,
471 		    DS_MODE_NONE, tag, &ds);
472 		if (err)
473 			goto out;
474 		obj = ds->ds_phys->ds_snapnames_zapobj;
475 		dsl_dataset_close(ds, DS_MODE_NONE, tag);
476 		ds = NULL;
477 
478 		if (tail[0] != '@') {
479 			err = ENOENT;
480 			goto out;
481 		}
482 		tail++;
483 
484 		/* Look for a snapshot */
485 		if (!DS_MODE_IS_READONLY(mode)) {
486 			err = EROFS;
487 			goto out;
488 		}
489 		dprintf("looking for snapshot '%s'\n", tail);
490 		err = zap_lookup(mos, obj, tail, 8, 1, &obj);
491 		if (err)
492 			goto out;
493 	}
494 	err = dsl_dataset_open_obj(dp, obj, tail, mode, tag, &ds);
495 
496 out:
497 	rw_exit(&dp->dp_config_rwlock);
498 	dsl_dir_close(dd, FTAG);
499 
500 	ASSERT3U((err == 0), ==, (ds != NULL));
501 	/* ASSERT(ds == NULL || strcmp(name, ds->ds_name) == 0); */
502 
503 	*dsp = ds;
504 	return (err);
505 }
506 
507 int
508 dsl_dataset_open(const char *name, int mode, void *tag, dsl_dataset_t **dsp)
509 {
510 	return (dsl_dataset_open_spa(NULL, name, mode, tag, dsp));
511 }
512 
513 void
514 dsl_dataset_name(dsl_dataset_t *ds, char *name)
515 {
516 	if (ds == NULL) {
517 		(void) strcpy(name, "mos");
518 	} else {
519 		dsl_dir_name(ds->ds_dir, name);
520 		VERIFY(0 == dsl_dataset_get_snapname(ds));
521 		if (ds->ds_snapname[0]) {
522 			(void) strcat(name, "@");
523 			if (!MUTEX_HELD(&ds->ds_lock)) {
524 				/*
525 				 * We use a "recursive" mutex so that we
526 				 * can call dprintf_ds() with ds_lock held.
527 				 */
528 				mutex_enter(&ds->ds_lock);
529 				(void) strcat(name, ds->ds_snapname);
530 				mutex_exit(&ds->ds_lock);
531 			} else {
532 				(void) strcat(name, ds->ds_snapname);
533 			}
534 		}
535 	}
536 }
537 
538 static int
539 dsl_dataset_namelen(dsl_dataset_t *ds)
540 {
541 	int result;
542 
543 	if (ds == NULL) {
544 		result = 3;	/* "mos" */
545 	} else {
546 		result = dsl_dir_namelen(ds->ds_dir);
547 		VERIFY(0 == dsl_dataset_get_snapname(ds));
548 		if (ds->ds_snapname[0]) {
549 			++result;	/* adding one for the @-sign */
550 			if (!MUTEX_HELD(&ds->ds_lock)) {
551 				/* see dsl_datset_name */
552 				mutex_enter(&ds->ds_lock);
553 				result += strlen(ds->ds_snapname);
554 				mutex_exit(&ds->ds_lock);
555 			} else {
556 				result += strlen(ds->ds_snapname);
557 			}
558 		}
559 	}
560 
561 	return (result);
562 }
563 
564 void
565 dsl_dataset_close(dsl_dataset_t *ds, int mode, void *tag)
566 {
567 	uint64_t weight = ds_refcnt_weight[DS_MODE_LEVEL(mode)];
568 	mutex_enter(&ds->ds_lock);
569 	ASSERT3U(ds->ds_open_refcount, >=, weight);
570 	ds->ds_open_refcount -= weight;
571 	dprintf_ds(ds, "closing mode %u refcount now 0x%llx\n",
572 	    mode, ds->ds_open_refcount);
573 	mutex_exit(&ds->ds_lock);
574 
575 	dmu_buf_rele(ds->ds_dbuf, tag);
576 }
577 
578 void
579 dsl_dataset_downgrade(dsl_dataset_t *ds, int oldmode, int newmode)
580 {
581 	uint64_t oldweight = ds_refcnt_weight[DS_MODE_LEVEL(oldmode)];
582 	uint64_t newweight = ds_refcnt_weight[DS_MODE_LEVEL(newmode)];
583 	mutex_enter(&ds->ds_lock);
584 	ASSERT3U(ds->ds_open_refcount, >=, oldweight);
585 	ASSERT3U(oldweight, >=, newweight);
586 	ds->ds_open_refcount -= oldweight;
587 	ds->ds_open_refcount += newweight;
588 	mutex_exit(&ds->ds_lock);
589 }
590 
591 boolean_t
592 dsl_dataset_tryupgrade(dsl_dataset_t *ds, int oldmode, int newmode)
593 {
594 	boolean_t rv;
595 	uint64_t oldweight = ds_refcnt_weight[DS_MODE_LEVEL(oldmode)];
596 	uint64_t newweight = ds_refcnt_weight[DS_MODE_LEVEL(newmode)];
597 	mutex_enter(&ds->ds_lock);
598 	ASSERT3U(ds->ds_open_refcount, >=, oldweight);
599 	ASSERT3U(newweight, >=, oldweight);
600 	if (ds->ds_open_refcount - oldweight + newweight > DS_REF_MAX) {
601 		rv = B_FALSE;
602 	} else {
603 		ds->ds_open_refcount -= oldweight;
604 		ds->ds_open_refcount += newweight;
605 		rv = B_TRUE;
606 	}
607 	mutex_exit(&ds->ds_lock);
608 	return (rv);
609 }
610 
611 void
612 dsl_dataset_create_root(dsl_pool_t *dp, uint64_t *ddobjp, dmu_tx_t *tx)
613 {
614 	objset_t *mos = dp->dp_meta_objset;
615 	dmu_buf_t *dbuf;
616 	dsl_dataset_phys_t *dsphys;
617 	dsl_dataset_t *ds;
618 	uint64_t dsobj;
619 	dsl_dir_t *dd;
620 
621 	dsl_dir_create_root(mos, ddobjp, tx);
622 	VERIFY(0 == dsl_dir_open_obj(dp, *ddobjp, NULL, FTAG, &dd));
623 
624 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
625 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
626 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
627 	dmu_buf_will_dirty(dbuf, tx);
628 	dsphys = dbuf->db_data;
629 	dsphys->ds_dir_obj = dd->dd_object;
630 	dsphys->ds_fsid_guid = unique_create();
631 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
632 	    sizeof (dsphys->ds_guid));
633 	dsphys->ds_snapnames_zapobj =
634 	    zap_create(mos, DMU_OT_DSL_DS_SNAP_MAP, DMU_OT_NONE, 0, tx);
635 	dsphys->ds_creation_time = gethrestime_sec();
636 	dsphys->ds_creation_txg = tx->tx_txg;
637 	dsphys->ds_deadlist_obj =
638 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
639 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
640 		dsphys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
641 	dmu_buf_rele(dbuf, FTAG);
642 
643 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
644 	dd->dd_phys->dd_head_dataset_obj = dsobj;
645 	dsl_dir_close(dd, FTAG);
646 
647 	VERIFY(0 ==
648 	    dsl_dataset_open_obj(dp, dsobj, NULL, DS_MODE_NONE, FTAG, &ds));
649 	(void) dmu_objset_create_impl(dp->dp_spa, ds,
650 	    &ds->ds_phys->ds_bp, DMU_OST_ZFS, tx);
651 	dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
652 }
653 
654 uint64_t
655 dsl_dataset_create_sync_impl(dsl_dir_t *dd, dsl_dataset_t *origin, dmu_tx_t *tx)
656 {
657 	dsl_pool_t *dp = dd->dd_pool;
658 	dmu_buf_t *dbuf;
659 	dsl_dataset_phys_t *dsphys;
660 	uint64_t dsobj;
661 	objset_t *mos = dp->dp_meta_objset;
662 
663 	ASSERT(origin == NULL || origin->ds_dir->dd_pool == dp);
664 	ASSERT(origin == NULL || origin->ds_phys->ds_num_children > 0);
665 	ASSERT(dmu_tx_is_syncing(tx));
666 	ASSERT(dd->dd_phys->dd_head_dataset_obj == 0);
667 
668 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
669 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
670 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
671 	dmu_buf_will_dirty(dbuf, tx);
672 	dsphys = dbuf->db_data;
673 	dsphys->ds_dir_obj = dd->dd_object;
674 	dsphys->ds_fsid_guid = unique_create();
675 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
676 	    sizeof (dsphys->ds_guid));
677 	dsphys->ds_snapnames_zapobj =
678 	    zap_create(mos, DMU_OT_DSL_DS_SNAP_MAP, DMU_OT_NONE, 0, tx);
679 	dsphys->ds_creation_time = gethrestime_sec();
680 	dsphys->ds_creation_txg = tx->tx_txg;
681 	dsphys->ds_deadlist_obj =
682 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
683 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
684 		dsphys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
685 
686 	if (origin) {
687 		dsphys->ds_prev_snap_obj = origin->ds_object;
688 		dsphys->ds_prev_snap_txg =
689 		    origin->ds_phys->ds_creation_txg;
690 		dsphys->ds_used_bytes =
691 		    origin->ds_phys->ds_used_bytes;
692 		dsphys->ds_compressed_bytes =
693 		    origin->ds_phys->ds_compressed_bytes;
694 		dsphys->ds_uncompressed_bytes =
695 		    origin->ds_phys->ds_uncompressed_bytes;
696 		dsphys->ds_bp = origin->ds_phys->ds_bp;
697 
698 		dmu_buf_will_dirty(origin->ds_dbuf, tx);
699 		origin->ds_phys->ds_num_children++;
700 
701 		dmu_buf_will_dirty(dd->dd_dbuf, tx);
702 		dd->dd_phys->dd_origin_obj = origin->ds_object;
703 	}
704 	dmu_buf_rele(dbuf, FTAG);
705 
706 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
707 	dd->dd_phys->dd_head_dataset_obj = dsobj;
708 
709 	return (dsobj);
710 }
711 
712 uint64_t
713 dsl_dataset_create_sync(dsl_dir_t *pdd,
714     const char *lastname, dsl_dataset_t *origin, cred_t *cr, dmu_tx_t *tx)
715 {
716 	dsl_pool_t *dp = pdd->dd_pool;
717 	uint64_t dsobj, ddobj;
718 	dsl_dir_t *dd;
719 
720 	ASSERT(lastname[0] != '@');
721 
722 	ddobj = dsl_dir_create_sync(pdd, lastname, tx);
723 	VERIFY(0 == dsl_dir_open_obj(dp, ddobj, lastname, FTAG, &dd));
724 
725 	dsobj = dsl_dataset_create_sync_impl(dd, origin, tx);
726 
727 	dsl_deleg_set_create_perms(dd, tx, cr);
728 
729 	dsl_dir_close(dd, FTAG);
730 
731 	return (dsobj);
732 }
733 
734 struct destroyarg {
735 	dsl_sync_task_group_t *dstg;
736 	char *snapname;
737 	char *failed;
738 };
739 
740 static int
741 dsl_snapshot_destroy_one(char *name, void *arg)
742 {
743 	struct destroyarg *da = arg;
744 	dsl_dataset_t *ds;
745 	char *cp;
746 	int err;
747 
748 	(void) strcat(name, "@");
749 	(void) strcat(name, da->snapname);
750 	err = dsl_dataset_open(name,
751 	    DS_MODE_EXCLUSIVE | DS_MODE_READONLY | DS_MODE_INCONSISTENT,
752 	    da->dstg, &ds);
753 	cp = strchr(name, '@');
754 	*cp = '\0';
755 	if (err == ENOENT)
756 		return (0);
757 	if (err) {
758 		(void) strcpy(da->failed, name);
759 		return (err);
760 	}
761 
762 	dsl_sync_task_create(da->dstg, dsl_dataset_destroy_check,
763 	    dsl_dataset_destroy_sync, ds, da->dstg, 0);
764 	return (0);
765 }
766 
767 /*
768  * Destroy 'snapname' in all descendants of 'fsname'.
769  */
770 #pragma weak dmu_snapshots_destroy = dsl_snapshots_destroy
771 int
772 dsl_snapshots_destroy(char *fsname, char *snapname)
773 {
774 	int err;
775 	struct destroyarg da;
776 	dsl_sync_task_t *dst;
777 	spa_t *spa;
778 
779 	err = spa_open(fsname, &spa, FTAG);
780 	if (err)
781 		return (err);
782 	da.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
783 	da.snapname = snapname;
784 	da.failed = fsname;
785 
786 	err = dmu_objset_find(fsname,
787 	    dsl_snapshot_destroy_one, &da, DS_FIND_CHILDREN);
788 
789 	if (err == 0)
790 		err = dsl_sync_task_group_wait(da.dstg);
791 
792 	for (dst = list_head(&da.dstg->dstg_tasks); dst;
793 	    dst = list_next(&da.dstg->dstg_tasks, dst)) {
794 		dsl_dataset_t *ds = dst->dst_arg1;
795 		if (dst->dst_err) {
796 			dsl_dataset_name(ds, fsname);
797 			*strchr(fsname, '@') = '\0';
798 		}
799 		/*
800 		 * If it was successful, destroy_sync would have
801 		 * closed the ds
802 		 */
803 		if (err)
804 			dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, da.dstg);
805 	}
806 
807 	dsl_sync_task_group_destroy(da.dstg);
808 	spa_close(spa, FTAG);
809 	return (err);
810 }
811 
812 /*
813  * ds must be opened EXCLUSIVE or PRIMARY.  on return (whether
814  * successful or not), ds will be closed and caller can no longer
815  * dereference it.
816  */
817 int
818 dsl_dataset_destroy(dsl_dataset_t *ds, void *tag)
819 {
820 	int err;
821 	dsl_sync_task_group_t *dstg;
822 	objset_t *os;
823 	dsl_dir_t *dd;
824 	uint64_t obj;
825 
826 	if (ds->ds_open_refcount != DS_REF_MAX) {
827 		if (dsl_dataset_tryupgrade(ds, DS_MODE_PRIMARY,
828 		    DS_MODE_EXCLUSIVE) == 0) {
829 			dsl_dataset_close(ds, DS_MODE_PRIMARY, tag);
830 			return (EBUSY);
831 		}
832 	}
833 
834 	if (dsl_dataset_is_snapshot(ds)) {
835 		/* Destroying a snapshot is simpler */
836 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
837 		    dsl_dataset_destroy_check, dsl_dataset_destroy_sync,
838 		    ds, tag, 0);
839 		goto out;
840 	}
841 
842 	dd = ds->ds_dir;
843 
844 	/*
845 	 * Check for errors and mark this ds as inconsistent, in
846 	 * case we crash while freeing the objects.
847 	 */
848 	err = dsl_sync_task_do(dd->dd_pool, dsl_dataset_destroy_begin_check,
849 	    dsl_dataset_destroy_begin_sync, ds, NULL, 0);
850 	if (err)
851 		goto out;
852 
853 	err = dmu_objset_open_ds(ds, DMU_OST_ANY, &os);
854 	if (err)
855 		goto out;
856 
857 	/*
858 	 * remove the objects in open context, so that we won't
859 	 * have too much to do in syncing context.
860 	 */
861 	for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE,
862 	    ds->ds_phys->ds_prev_snap_txg)) {
863 		dmu_tx_t *tx = dmu_tx_create(os);
864 		dmu_tx_hold_free(tx, obj, 0, DMU_OBJECT_END);
865 		dmu_tx_hold_bonus(tx, obj);
866 		err = dmu_tx_assign(tx, TXG_WAIT);
867 		if (err) {
868 			/*
869 			 * Perhaps there is not enough disk
870 			 * space.  Just deal with it from
871 			 * dsl_dataset_destroy_sync().
872 			 */
873 			dmu_tx_abort(tx);
874 			continue;
875 		}
876 		VERIFY(0 == dmu_object_free(os, obj, tx));
877 		dmu_tx_commit(tx);
878 	}
879 	/* Make sure it's not dirty before we finish destroying it. */
880 	txg_wait_synced(dd->dd_pool, 0);
881 
882 	dmu_objset_close(os);
883 	if (err != ESRCH)
884 		goto out;
885 
886 	if (ds->ds_user_ptr) {
887 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
888 		ds->ds_user_ptr = NULL;
889 	}
890 
891 	rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
892 	err = dsl_dir_open_obj(dd->dd_pool, dd->dd_object, NULL, FTAG, &dd);
893 	rw_exit(&dd->dd_pool->dp_config_rwlock);
894 
895 	if (err)
896 		goto out;
897 
898 	/*
899 	 * Blow away the dsl_dir + head dataset.
900 	 */
901 	dstg = dsl_sync_task_group_create(ds->ds_dir->dd_pool);
902 	dsl_sync_task_create(dstg, dsl_dataset_destroy_check,
903 	    dsl_dataset_destroy_sync, ds, tag, 0);
904 	dsl_sync_task_create(dstg, dsl_dir_destroy_check,
905 	    dsl_dir_destroy_sync, dd, FTAG, 0);
906 	err = dsl_sync_task_group_wait(dstg);
907 	dsl_sync_task_group_destroy(dstg);
908 	/* if it is successful, *destroy_sync will close the ds+dd */
909 	if (err)
910 		dsl_dir_close(dd, FTAG);
911 out:
912 	if (err)
913 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, tag);
914 	return (err);
915 }
916 
917 int
918 dsl_dataset_rollback(dsl_dataset_t *ds, dmu_objset_type_t ost)
919 {
920 	ASSERT3U(ds->ds_open_refcount, ==, DS_REF_MAX);
921 
922 	return (dsl_sync_task_do(ds->ds_dir->dd_pool,
923 	    dsl_dataset_rollback_check, dsl_dataset_rollback_sync,
924 	    ds, &ost, 0));
925 }
926 
927 void *
928 dsl_dataset_set_user_ptr(dsl_dataset_t *ds,
929     void *p, dsl_dataset_evict_func_t func)
930 {
931 	void *old;
932 
933 	mutex_enter(&ds->ds_lock);
934 	old = ds->ds_user_ptr;
935 	if (old == NULL) {
936 		ds->ds_user_ptr = p;
937 		ds->ds_user_evict_func = func;
938 	}
939 	mutex_exit(&ds->ds_lock);
940 	return (old);
941 }
942 
943 void *
944 dsl_dataset_get_user_ptr(dsl_dataset_t *ds)
945 {
946 	return (ds->ds_user_ptr);
947 }
948 
949 
950 blkptr_t *
951 dsl_dataset_get_blkptr(dsl_dataset_t *ds)
952 {
953 	return (&ds->ds_phys->ds_bp);
954 }
955 
956 void
957 dsl_dataset_set_blkptr(dsl_dataset_t *ds, blkptr_t *bp, dmu_tx_t *tx)
958 {
959 	ASSERT(dmu_tx_is_syncing(tx));
960 	/* If it's the meta-objset, set dp_meta_rootbp */
961 	if (ds == NULL) {
962 		tx->tx_pool->dp_meta_rootbp = *bp;
963 	} else {
964 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
965 		ds->ds_phys->ds_bp = *bp;
966 	}
967 }
968 
969 spa_t *
970 dsl_dataset_get_spa(dsl_dataset_t *ds)
971 {
972 	return (ds->ds_dir->dd_pool->dp_spa);
973 }
974 
975 void
976 dsl_dataset_dirty(dsl_dataset_t *ds, dmu_tx_t *tx)
977 {
978 	dsl_pool_t *dp;
979 
980 	if (ds == NULL) /* this is the meta-objset */
981 		return;
982 
983 	ASSERT(ds->ds_user_ptr != NULL);
984 
985 	if (ds->ds_phys->ds_next_snap_obj != 0)
986 		panic("dirtying snapshot!");
987 
988 	dp = ds->ds_dir->dd_pool;
989 
990 	if (txg_list_add(&dp->dp_dirty_datasets, ds, tx->tx_txg) == 0) {
991 		/* up the hold count until we can be written out */
992 		dmu_buf_add_ref(ds->ds_dbuf, ds);
993 	}
994 }
995 
996 /*
997  * The unique space in the head dataset can be calculated by subtracting
998  * the space used in the most recent snapshot, that is still being used
999  * in this file system, from the space currently in use.  To figure out
1000  * the space in the most recent snapshot still in use, we need to take
1001  * the total space used in the snapshot and subtract out the space that
1002  * has been freed up since the snapshot was taken.
1003  */
1004 static void
1005 dsl_dataset_recalc_head_uniq(dsl_dataset_t *ds)
1006 {
1007 	uint64_t mrs_used;
1008 	uint64_t dlused, dlcomp, dluncomp;
1009 
1010 	ASSERT(ds->ds_object == ds->ds_dir->dd_phys->dd_head_dataset_obj);
1011 
1012 	if (ds->ds_phys->ds_prev_snap_obj != 0)
1013 		mrs_used = ds->ds_prev->ds_phys->ds_used_bytes;
1014 	else
1015 		mrs_used = 0;
1016 
1017 	VERIFY(0 == bplist_space(&ds->ds_deadlist, &dlused, &dlcomp,
1018 	    &dluncomp));
1019 
1020 	ASSERT3U(dlused, <=, mrs_used);
1021 	ds->ds_phys->ds_unique_bytes =
1022 	    ds->ds_phys->ds_used_bytes - (mrs_used - dlused);
1023 
1024 	if (!DS_UNIQUE_IS_ACCURATE(ds) &&
1025 	    spa_version(ds->ds_dir->dd_pool->dp_spa) >=
1026 	    SPA_VERSION_UNIQUE_ACCURATE)
1027 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
1028 }
1029 
1030 static uint64_t
1031 dsl_dataset_unique(dsl_dataset_t *ds)
1032 {
1033 	if (!DS_UNIQUE_IS_ACCURATE(ds) && !dsl_dataset_is_snapshot(ds))
1034 		dsl_dataset_recalc_head_uniq(ds);
1035 
1036 	return (ds->ds_phys->ds_unique_bytes);
1037 }
1038 
1039 struct killarg {
1040 	int64_t *usedp;
1041 	int64_t *compressedp;
1042 	int64_t *uncompressedp;
1043 	zio_t *zio;
1044 	dmu_tx_t *tx;
1045 };
1046 
1047 static int
1048 kill_blkptr(traverse_blk_cache_t *bc, spa_t *spa, void *arg)
1049 {
1050 	struct killarg *ka = arg;
1051 	blkptr_t *bp = &bc->bc_blkptr;
1052 
1053 	ASSERT3U(bc->bc_errno, ==, 0);
1054 
1055 	/*
1056 	 * Since this callback is not called concurrently, no lock is
1057 	 * needed on the accounting values.
1058 	 */
1059 	*ka->usedp += bp_get_dasize(spa, bp);
1060 	*ka->compressedp += BP_GET_PSIZE(bp);
1061 	*ka->uncompressedp += BP_GET_UCSIZE(bp);
1062 	/* XXX check for EIO? */
1063 	(void) arc_free(ka->zio, spa, ka->tx->tx_txg, bp, NULL, NULL,
1064 	    ARC_NOWAIT);
1065 	return (0);
1066 }
1067 
1068 /* ARGSUSED */
1069 static int
1070 dsl_dataset_rollback_check(void *arg1, void *arg2, dmu_tx_t *tx)
1071 {
1072 	dsl_dataset_t *ds = arg1;
1073 	dmu_objset_type_t *ost = arg2;
1074 
1075 	/*
1076 	 * We can only roll back to emptyness if it is a ZPL objset.
1077 	 */
1078 	if (*ost != DMU_OST_ZFS && ds->ds_phys->ds_prev_snap_txg == 0)
1079 		return (EINVAL);
1080 
1081 	/*
1082 	 * This must not be a snapshot.
1083 	 */
1084 	if (ds->ds_phys->ds_next_snap_obj != 0)
1085 		return (EINVAL);
1086 
1087 	/*
1088 	 * If we made changes this txg, traverse_dsl_dataset won't find
1089 	 * them.  Try again.
1090 	 */
1091 	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
1092 		return (EAGAIN);
1093 
1094 	return (0);
1095 }
1096 
1097 /* ARGSUSED */
1098 static void
1099 dsl_dataset_rollback_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1100 {
1101 	dsl_dataset_t *ds = arg1;
1102 	dmu_objset_type_t *ost = arg2;
1103 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
1104 
1105 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1106 
1107 	/*
1108 	 * Before the roll back destroy the zil.
1109 	 */
1110 	if (ds->ds_user_ptr != NULL) {
1111 		zil_rollback_destroy(
1112 		    ((objset_impl_t *)ds->ds_user_ptr)->os_zil, tx);
1113 
1114 		/*
1115 		 * We need to make sure that the objset_impl_t is reopened after
1116 		 * we do the rollback, otherwise it will have the wrong
1117 		 * objset_phys_t.  Normally this would happen when this
1118 		 * DS_MODE_EXCLUSIVE dataset-open is closed, thus causing the
1119 		 * dataset to be immediately evicted.  But when doing "zfs recv
1120 		 * -F", we reopen the objset before that, so that there is no
1121 		 * window where the dataset is closed and inconsistent.
1122 		 */
1123 		ds->ds_user_evict_func(ds, ds->ds_user_ptr);
1124 		ds->ds_user_ptr = NULL;
1125 	}
1126 
1127 	/* Zero out the deadlist. */
1128 	bplist_close(&ds->ds_deadlist);
1129 	bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
1130 	ds->ds_phys->ds_deadlist_obj =
1131 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
1132 	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
1133 	    ds->ds_phys->ds_deadlist_obj));
1134 
1135 	{
1136 		/* Free blkptrs that we gave birth to */
1137 		zio_t *zio;
1138 		int64_t used = 0, compressed = 0, uncompressed = 0;
1139 		struct killarg ka;
1140 
1141 		zio = zio_root(tx->tx_pool->dp_spa, NULL, NULL,
1142 		    ZIO_FLAG_MUSTSUCCEED);
1143 		ka.usedp = &used;
1144 		ka.compressedp = &compressed;
1145 		ka.uncompressedp = &uncompressed;
1146 		ka.zio = zio;
1147 		ka.tx = tx;
1148 		(void) traverse_dsl_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
1149 		    ADVANCE_POST, kill_blkptr, &ka);
1150 		(void) zio_wait(zio);
1151 
1152 		dsl_dir_diduse_space(ds->ds_dir,
1153 		    -used, -compressed, -uncompressed, tx);
1154 	}
1155 
1156 	if (ds->ds_prev) {
1157 		/* Change our contents to that of the prev snapshot */
1158 		ASSERT3U(ds->ds_prev->ds_object, ==,
1159 		    ds->ds_phys->ds_prev_snap_obj);
1160 		ds->ds_phys->ds_bp = ds->ds_prev->ds_phys->ds_bp;
1161 		ds->ds_phys->ds_used_bytes =
1162 		    ds->ds_prev->ds_phys->ds_used_bytes;
1163 		ds->ds_phys->ds_compressed_bytes =
1164 		    ds->ds_prev->ds_phys->ds_compressed_bytes;
1165 		ds->ds_phys->ds_uncompressed_bytes =
1166 		    ds->ds_prev->ds_phys->ds_uncompressed_bytes;
1167 		ds->ds_phys->ds_flags = ds->ds_prev->ds_phys->ds_flags;
1168 		ds->ds_phys->ds_unique_bytes = 0;
1169 
1170 		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
1171 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
1172 			ds->ds_prev->ds_phys->ds_unique_bytes = 0;
1173 		}
1174 	} else {
1175 		/* Zero out our contents, recreate objset */
1176 		bzero(&ds->ds_phys->ds_bp, sizeof (blkptr_t));
1177 		ds->ds_phys->ds_used_bytes = 0;
1178 		ds->ds_phys->ds_compressed_bytes = 0;
1179 		ds->ds_phys->ds_uncompressed_bytes = 0;
1180 		ds->ds_phys->ds_flags = 0;
1181 		ds->ds_phys->ds_unique_bytes = 0;
1182 		(void) dmu_objset_create_impl(ds->ds_dir->dd_pool->dp_spa, ds,
1183 		    &ds->ds_phys->ds_bp, *ost, tx);
1184 	}
1185 
1186 	spa_history_internal_log(LOG_DS_ROLLBACK, ds->ds_dir->dd_pool->dp_spa,
1187 	    tx, cr, "dataset = %llu", ds->ds_object);
1188 }
1189 
1190 /* ARGSUSED */
1191 static int
1192 dsl_dataset_destroy_begin_check(void *arg1, void *arg2, dmu_tx_t *tx)
1193 {
1194 	dsl_dataset_t *ds = arg1;
1195 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
1196 	uint64_t count;
1197 	int err;
1198 
1199 	/*
1200 	 * Can't delete a head dataset if there are snapshots of it.
1201 	 * (Except if the only snapshots are from the branch we cloned
1202 	 * from.)
1203 	 */
1204 	if (ds->ds_prev != NULL &&
1205 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
1206 		return (EINVAL);
1207 
1208 	/*
1209 	 * This is really a dsl_dir thing, but check it here so that
1210 	 * we'll be less likely to leave this dataset inconsistent &
1211 	 * nearly destroyed.
1212 	 */
1213 	err = zap_count(mos, ds->ds_dir->dd_phys->dd_child_dir_zapobj, &count);
1214 	if (err)
1215 		return (err);
1216 	if (count != 0)
1217 		return (EEXIST);
1218 
1219 	return (0);
1220 }
1221 
1222 /* ARGSUSED */
1223 static void
1224 dsl_dataset_destroy_begin_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1225 {
1226 	dsl_dataset_t *ds = arg1;
1227 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1228 
1229 	/* Mark it as inconsistent on-disk, in case we crash */
1230 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1231 	ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
1232 
1233 	spa_history_internal_log(LOG_DS_DESTROY_BEGIN, dp->dp_spa, tx,
1234 	    cr, "dataset = %llu", ds->ds_object);
1235 }
1236 
1237 /* ARGSUSED */
1238 int
1239 dsl_dataset_destroy_check(void *arg1, void *arg2, dmu_tx_t *tx)
1240 {
1241 	dsl_dataset_t *ds = arg1;
1242 
1243 	/* Can't delete a branch point. */
1244 	if (ds->ds_phys->ds_num_children > 1)
1245 		return (EEXIST);
1246 
1247 	/*
1248 	 * Can't delete a head dataset if there are snapshots of it.
1249 	 * (Except if the only snapshots are from the branch we cloned
1250 	 * from.)
1251 	 */
1252 	if (ds->ds_prev != NULL &&
1253 	    ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object)
1254 		return (EINVAL);
1255 
1256 	/*
1257 	 * If we made changes this txg, traverse_dsl_dataset won't find
1258 	 * them.  Try again.
1259 	 */
1260 	if (ds->ds_phys->ds_bp.blk_birth >= tx->tx_txg)
1261 		return (EAGAIN);
1262 
1263 	/* XXX we should do some i/o error checking... */
1264 	return (0);
1265 }
1266 
1267 void
1268 dsl_dataset_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
1269 {
1270 	dsl_dataset_t *ds = arg1;
1271 	int64_t used = 0, compressed = 0, uncompressed = 0;
1272 	zio_t *zio;
1273 	int err;
1274 	int after_branch_point = FALSE;
1275 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1276 	objset_t *mos = dp->dp_meta_objset;
1277 	dsl_dataset_t *ds_prev = NULL;
1278 	uint64_t obj;
1279 
1280 	ASSERT3U(ds->ds_open_refcount, ==, DS_REF_MAX);
1281 	ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
1282 	ASSERT(ds->ds_prev == NULL ||
1283 	    ds->ds_prev->ds_phys->ds_next_snap_obj != ds->ds_object);
1284 	ASSERT3U(ds->ds_phys->ds_bp.blk_birth, <=, tx->tx_txg);
1285 
1286 	/* Remove our reservation */
1287 	if (ds->ds_reserved != 0) {
1288 		uint64_t val = 0;
1289 		dsl_dataset_set_reservation_sync(ds, &val, cr, tx);
1290 		ASSERT3U(ds->ds_reserved, ==, 0);
1291 	}
1292 
1293 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
1294 
1295 	obj = ds->ds_object;
1296 
1297 	if (ds->ds_phys->ds_prev_snap_obj != 0) {
1298 		if (ds->ds_prev) {
1299 			ds_prev = ds->ds_prev;
1300 		} else {
1301 			VERIFY(0 == dsl_dataset_open_obj(dp,
1302 			    ds->ds_phys->ds_prev_snap_obj, NULL,
1303 			    DS_MODE_NONE, FTAG, &ds_prev));
1304 		}
1305 		after_branch_point =
1306 		    (ds_prev->ds_phys->ds_next_snap_obj != obj);
1307 
1308 		dmu_buf_will_dirty(ds_prev->ds_dbuf, tx);
1309 		if (after_branch_point &&
1310 		    ds->ds_phys->ds_next_snap_obj == 0) {
1311 			/* This clone is toast. */
1312 			ASSERT(ds_prev->ds_phys->ds_num_children > 1);
1313 			ds_prev->ds_phys->ds_num_children--;
1314 		} else if (!after_branch_point) {
1315 			ds_prev->ds_phys->ds_next_snap_obj =
1316 			    ds->ds_phys->ds_next_snap_obj;
1317 		}
1318 	}
1319 
1320 	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
1321 
1322 	if (ds->ds_phys->ds_next_snap_obj != 0) {
1323 		blkptr_t bp;
1324 		dsl_dataset_t *ds_next;
1325 		uint64_t itor = 0;
1326 		uint64_t old_unique;
1327 
1328 		spa_scrub_restart(dp->dp_spa, tx->tx_txg);
1329 
1330 		VERIFY(0 == dsl_dataset_open_obj(dp,
1331 		    ds->ds_phys->ds_next_snap_obj, NULL,
1332 		    DS_MODE_NONE, FTAG, &ds_next));
1333 		ASSERT3U(ds_next->ds_phys->ds_prev_snap_obj, ==, obj);
1334 
1335 		old_unique = dsl_dataset_unique(ds_next);
1336 
1337 		dmu_buf_will_dirty(ds_next->ds_dbuf, tx);
1338 		ds_next->ds_phys->ds_prev_snap_obj =
1339 		    ds->ds_phys->ds_prev_snap_obj;
1340 		ds_next->ds_phys->ds_prev_snap_txg =
1341 		    ds->ds_phys->ds_prev_snap_txg;
1342 		ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
1343 		    ds_prev ? ds_prev->ds_phys->ds_creation_txg : 0);
1344 
1345 		/*
1346 		 * Transfer to our deadlist (which will become next's
1347 		 * new deadlist) any entries from next's current
1348 		 * deadlist which were born before prev, and free the
1349 		 * other entries.
1350 		 *
1351 		 * XXX we're doing this long task with the config lock held
1352 		 */
1353 		while (bplist_iterate(&ds_next->ds_deadlist, &itor,
1354 		    &bp) == 0) {
1355 			if (bp.blk_birth <= ds->ds_phys->ds_prev_snap_txg) {
1356 				VERIFY(0 == bplist_enqueue(&ds->ds_deadlist,
1357 				    &bp, tx));
1358 				if (ds_prev && !after_branch_point &&
1359 				    bp.blk_birth >
1360 				    ds_prev->ds_phys->ds_prev_snap_txg) {
1361 					ds_prev->ds_phys->ds_unique_bytes +=
1362 					    bp_get_dasize(dp->dp_spa, &bp);
1363 				}
1364 			} else {
1365 				used += bp_get_dasize(dp->dp_spa, &bp);
1366 				compressed += BP_GET_PSIZE(&bp);
1367 				uncompressed += BP_GET_UCSIZE(&bp);
1368 				/* XXX check return value? */
1369 				(void) arc_free(zio, dp->dp_spa, tx->tx_txg,
1370 				    &bp, NULL, NULL, ARC_NOWAIT);
1371 			}
1372 		}
1373 
1374 		/* free next's deadlist */
1375 		bplist_close(&ds_next->ds_deadlist);
1376 		bplist_destroy(mos, ds_next->ds_phys->ds_deadlist_obj, tx);
1377 
1378 		/* set next's deadlist to our deadlist */
1379 		ds_next->ds_phys->ds_deadlist_obj =
1380 		    ds->ds_phys->ds_deadlist_obj;
1381 		VERIFY(0 == bplist_open(&ds_next->ds_deadlist, mos,
1382 		    ds_next->ds_phys->ds_deadlist_obj));
1383 		ds->ds_phys->ds_deadlist_obj = 0;
1384 
1385 		if (ds_next->ds_phys->ds_next_snap_obj != 0) {
1386 			/*
1387 			 * Update next's unique to include blocks which
1388 			 * were previously shared by only this snapshot
1389 			 * and it.  Those blocks will be born after the
1390 			 * prev snap and before this snap, and will have
1391 			 * died after the next snap and before the one
1392 			 * after that (ie. be on the snap after next's
1393 			 * deadlist).
1394 			 *
1395 			 * XXX we're doing this long task with the
1396 			 * config lock held
1397 			 */
1398 			dsl_dataset_t *ds_after_next;
1399 
1400 			VERIFY(0 == dsl_dataset_open_obj(dp,
1401 			    ds_next->ds_phys->ds_next_snap_obj, NULL,
1402 			    DS_MODE_NONE, FTAG, &ds_after_next));
1403 			itor = 0;
1404 			while (bplist_iterate(&ds_after_next->ds_deadlist,
1405 			    &itor, &bp) == 0) {
1406 				if (bp.blk_birth >
1407 				    ds->ds_phys->ds_prev_snap_txg &&
1408 				    bp.blk_birth <=
1409 				    ds->ds_phys->ds_creation_txg) {
1410 					ds_next->ds_phys->ds_unique_bytes +=
1411 					    bp_get_dasize(dp->dp_spa, &bp);
1412 				}
1413 			}
1414 
1415 			dsl_dataset_close(ds_after_next, DS_MODE_NONE, FTAG);
1416 			ASSERT3P(ds_next->ds_prev, ==, NULL);
1417 		} else {
1418 			ASSERT3P(ds_next->ds_prev, ==, ds);
1419 			dsl_dataset_close(ds_next->ds_prev, DS_MODE_NONE,
1420 			    ds_next);
1421 			if (ds_prev) {
1422 				VERIFY(0 == dsl_dataset_open_obj(dp,
1423 				    ds->ds_phys->ds_prev_snap_obj, NULL,
1424 				    DS_MODE_NONE, ds_next, &ds_next->ds_prev));
1425 			} else {
1426 				ds_next->ds_prev = NULL;
1427 			}
1428 
1429 			dsl_dataset_recalc_head_uniq(ds_next);
1430 
1431 			/*
1432 			 * Reduce the amount of our unconsmed refreservation
1433 			 * being charged to our parent by the amount of
1434 			 * new unique data we have gained.
1435 			 */
1436 			if (old_unique < ds_next->ds_reserved) {
1437 				int64_t mrsdelta;
1438 				uint64_t new_unique =
1439 				    ds_next->ds_phys->ds_unique_bytes;
1440 
1441 				ASSERT(old_unique <= new_unique);
1442 				mrsdelta = MIN(new_unique - old_unique,
1443 				    ds_next->ds_reserved - old_unique);
1444 				dsl_dir_diduse_space(ds->ds_dir, -mrsdelta,
1445 				    0, 0, tx);
1446 			}
1447 		}
1448 		dsl_dataset_close(ds_next, DS_MODE_NONE, FTAG);
1449 
1450 		/*
1451 		 * NB: unique_bytes might not be accurate for the head objset.
1452 		 * Before SPA_VERSION 9, we didn't update its value when we
1453 		 * deleted the most recent snapshot.
1454 		 */
1455 		ASSERT3U(used, ==, ds->ds_phys->ds_unique_bytes);
1456 	} else {
1457 		/*
1458 		 * There's no next snapshot, so this is a head dataset.
1459 		 * Destroy the deadlist.  Unless it's a clone, the
1460 		 * deadlist should be empty.  (If it's a clone, it's
1461 		 * safe to ignore the deadlist contents.)
1462 		 */
1463 		struct killarg ka;
1464 
1465 		ASSERT(after_branch_point || bplist_empty(&ds->ds_deadlist));
1466 		bplist_close(&ds->ds_deadlist);
1467 		bplist_destroy(mos, ds->ds_phys->ds_deadlist_obj, tx);
1468 		ds->ds_phys->ds_deadlist_obj = 0;
1469 
1470 		/*
1471 		 * Free everything that we point to (that's born after
1472 		 * the previous snapshot, if we are a clone)
1473 		 *
1474 		 * XXX we're doing this long task with the config lock held
1475 		 */
1476 		ka.usedp = &used;
1477 		ka.compressedp = &compressed;
1478 		ka.uncompressedp = &uncompressed;
1479 		ka.zio = zio;
1480 		ka.tx = tx;
1481 		err = traverse_dsl_dataset(ds, ds->ds_phys->ds_prev_snap_txg,
1482 		    ADVANCE_POST, kill_blkptr, &ka);
1483 		ASSERT3U(err, ==, 0);
1484 		ASSERT(spa_version(dp->dp_spa) <
1485 		    SPA_VERSION_UNIQUE_ACCURATE ||
1486 		    used == ds->ds_phys->ds_unique_bytes);
1487 	}
1488 
1489 	err = zio_wait(zio);
1490 	ASSERT3U(err, ==, 0);
1491 
1492 	dsl_dir_diduse_space(ds->ds_dir, -used, -compressed, -uncompressed, tx);
1493 
1494 	if (ds->ds_phys->ds_snapnames_zapobj) {
1495 		err = zap_destroy(mos, ds->ds_phys->ds_snapnames_zapobj, tx);
1496 		ASSERT(err == 0);
1497 	}
1498 
1499 	if (ds->ds_dir->dd_phys->dd_head_dataset_obj == ds->ds_object) {
1500 		/* Erase the link in the dataset */
1501 		dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
1502 		ds->ds_dir->dd_phys->dd_head_dataset_obj = 0;
1503 		/*
1504 		 * dsl_dir_sync_destroy() called us, they'll destroy
1505 		 * the dataset.
1506 		 */
1507 	} else {
1508 		/* remove from snapshot namespace */
1509 		dsl_dataset_t *ds_head;
1510 		VERIFY(0 == dsl_dataset_open_obj(dp,
1511 		    ds->ds_dir->dd_phys->dd_head_dataset_obj, NULL,
1512 		    DS_MODE_NONE, FTAG, &ds_head));
1513 		VERIFY(0 == dsl_dataset_get_snapname(ds));
1514 #ifdef ZFS_DEBUG
1515 		{
1516 			uint64_t val;
1517 			err = zap_lookup(mos,
1518 			    ds_head->ds_phys->ds_snapnames_zapobj,
1519 			    ds->ds_snapname, 8, 1, &val);
1520 			ASSERT3U(err, ==, 0);
1521 			ASSERT3U(val, ==, obj);
1522 		}
1523 #endif
1524 		err = zap_remove(mos, ds_head->ds_phys->ds_snapnames_zapobj,
1525 		    ds->ds_snapname, tx);
1526 		ASSERT(err == 0);
1527 		dsl_dataset_close(ds_head, DS_MODE_NONE, FTAG);
1528 	}
1529 
1530 	if (ds_prev && ds->ds_prev != ds_prev)
1531 		dsl_dataset_close(ds_prev, DS_MODE_NONE, FTAG);
1532 
1533 	spa_prop_clear_bootfs(dp->dp_spa, ds->ds_object, tx);
1534 	spa_history_internal_log(LOG_DS_DESTROY, dp->dp_spa, tx,
1535 	    cr, "dataset = %llu", ds->ds_object);
1536 
1537 	dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, tag);
1538 	VERIFY(0 == dmu_object_free(mos, obj, tx));
1539 
1540 }
1541 
1542 static int
1543 dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
1544 {
1545 	uint64_t asize;
1546 
1547 	if (!dmu_tx_is_syncing(tx))
1548 		return (0);
1549 
1550 	/*
1551 	 * If there's an fs-only reservation, any blocks that might become
1552 	 * owned by the snapshot dataset must be accommodated by space
1553 	 * outside of the reservation.
1554 	 */
1555 	asize = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
1556 	if (asize > dsl_dir_space_available(ds->ds_dir, NULL, 0, FALSE))
1557 		return (ENOSPC);
1558 
1559 	/*
1560 	 * Propogate any reserved space for this snapshot to other
1561 	 * snapshot checks in this sync group.
1562 	 */
1563 	if (asize > 0)
1564 		dsl_dir_willuse_space(ds->ds_dir, asize, tx);
1565 
1566 	return (0);
1567 }
1568 
1569 /* ARGSUSED */
1570 int
1571 dsl_dataset_snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
1572 {
1573 	dsl_dataset_t *ds = arg1;
1574 	const char *snapname = arg2;
1575 	objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
1576 	int err;
1577 	uint64_t value;
1578 
1579 	/*
1580 	 * We don't allow multiple snapshots of the same txg.  If there
1581 	 * is already one, try again.
1582 	 */
1583 	if (ds->ds_phys->ds_prev_snap_txg >= tx->tx_txg)
1584 		return (EAGAIN);
1585 
1586 	/*
1587 	 * Check for conflicting name snapshot name.
1588 	 */
1589 	err = zap_lookup(mos, ds->ds_phys->ds_snapnames_zapobj,
1590 	    snapname, 8, 1, &value);
1591 	if (err == 0)
1592 		return (EEXIST);
1593 	if (err != ENOENT)
1594 		return (err);
1595 
1596 	/*
1597 	 * Check that the dataset's name is not too long.  Name consists
1598 	 * of the dataset's length + 1 for the @-sign + snapshot name's length
1599 	 */
1600 	if (dsl_dataset_namelen(ds) + 1 + strlen(snapname) >= MAXNAMELEN)
1601 		return (ENAMETOOLONG);
1602 
1603 	err = dsl_dataset_snapshot_reserve_space(ds, tx);
1604 	if (err)
1605 		return (err);
1606 
1607 	ds->ds_trysnap_txg = tx->tx_txg;
1608 	return (0);
1609 }
1610 
1611 void
1612 dsl_dataset_snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1613 {
1614 	dsl_dataset_t *ds = arg1;
1615 	const char *snapname = arg2;
1616 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1617 	dmu_buf_t *dbuf;
1618 	dsl_dataset_phys_t *dsphys;
1619 	uint64_t dsobj;
1620 	objset_t *mos = dp->dp_meta_objset;
1621 	int err;
1622 
1623 	spa_scrub_restart(dp->dp_spa, tx->tx_txg);
1624 	ASSERT(RW_WRITE_HELD(&dp->dp_config_rwlock));
1625 
1626 	dsobj = dmu_object_alloc(mos, DMU_OT_DSL_DATASET, 0,
1627 	    DMU_OT_DSL_DATASET, sizeof (dsl_dataset_phys_t), tx);
1628 	VERIFY(0 == dmu_bonus_hold(mos, dsobj, FTAG, &dbuf));
1629 	dmu_buf_will_dirty(dbuf, tx);
1630 	dsphys = dbuf->db_data;
1631 	dsphys->ds_dir_obj = ds->ds_dir->dd_object;
1632 	dsphys->ds_fsid_guid = unique_create();
1633 	(void) random_get_pseudo_bytes((void*)&dsphys->ds_guid,
1634 	    sizeof (dsphys->ds_guid));
1635 	dsphys->ds_prev_snap_obj = ds->ds_phys->ds_prev_snap_obj;
1636 	dsphys->ds_prev_snap_txg = ds->ds_phys->ds_prev_snap_txg;
1637 	dsphys->ds_next_snap_obj = ds->ds_object;
1638 	dsphys->ds_num_children = 1;
1639 	dsphys->ds_creation_time = gethrestime_sec();
1640 	dsphys->ds_creation_txg = tx->tx_txg;
1641 	dsphys->ds_deadlist_obj = ds->ds_phys->ds_deadlist_obj;
1642 	dsphys->ds_used_bytes = ds->ds_phys->ds_used_bytes;
1643 	dsphys->ds_compressed_bytes = ds->ds_phys->ds_compressed_bytes;
1644 	dsphys->ds_uncompressed_bytes = ds->ds_phys->ds_uncompressed_bytes;
1645 	dsphys->ds_flags = ds->ds_phys->ds_flags;
1646 	dsphys->ds_bp = ds->ds_phys->ds_bp;
1647 	dmu_buf_rele(dbuf, FTAG);
1648 
1649 	ASSERT3U(ds->ds_prev != 0, ==, ds->ds_phys->ds_prev_snap_obj != 0);
1650 	if (ds->ds_prev) {
1651 		ASSERT(ds->ds_prev->ds_phys->ds_next_snap_obj ==
1652 		    ds->ds_object ||
1653 		    ds->ds_prev->ds_phys->ds_num_children > 1);
1654 		if (ds->ds_prev->ds_phys->ds_next_snap_obj == ds->ds_object) {
1655 			dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
1656 			ASSERT3U(ds->ds_phys->ds_prev_snap_txg, ==,
1657 			    ds->ds_prev->ds_phys->ds_creation_txg);
1658 			ds->ds_prev->ds_phys->ds_next_snap_obj = dsobj;
1659 		}
1660 	}
1661 
1662 	/*
1663 	 * If we have a reference-reservation on this dataset, we will
1664 	 * need to increase the amount of refreservation being charged
1665 	 * since our unique space is going to zero.
1666 	 */
1667 	if (ds->ds_reserved) {
1668 		int64_t add = MIN(dsl_dataset_unique(ds), ds->ds_reserved);
1669 		dsl_dir_diduse_space(ds->ds_dir, add, 0, 0, tx);
1670 	}
1671 
1672 	bplist_close(&ds->ds_deadlist);
1673 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1674 	ASSERT3U(ds->ds_phys->ds_prev_snap_txg, <, dsphys->ds_creation_txg);
1675 	ds->ds_phys->ds_prev_snap_obj = dsobj;
1676 	ds->ds_phys->ds_prev_snap_txg = dsphys->ds_creation_txg;
1677 	ds->ds_phys->ds_unique_bytes = 0;
1678 	if (spa_version(dp->dp_spa) >= SPA_VERSION_UNIQUE_ACCURATE)
1679 		ds->ds_phys->ds_flags |= DS_FLAG_UNIQUE_ACCURATE;
1680 	ds->ds_phys->ds_deadlist_obj =
1681 	    bplist_create(mos, DSL_DEADLIST_BLOCKSIZE, tx);
1682 	VERIFY(0 == bplist_open(&ds->ds_deadlist, mos,
1683 	    ds->ds_phys->ds_deadlist_obj));
1684 
1685 	dprintf("snap '%s' -> obj %llu\n", snapname, dsobj);
1686 	err = zap_add(mos, ds->ds_phys->ds_snapnames_zapobj,
1687 	    snapname, 8, 1, &dsobj, tx);
1688 	ASSERT(err == 0);
1689 
1690 	if (ds->ds_prev)
1691 		dsl_dataset_close(ds->ds_prev, DS_MODE_NONE, ds);
1692 	VERIFY(0 == dsl_dataset_open_obj(dp,
1693 	    ds->ds_phys->ds_prev_snap_obj, snapname,
1694 	    DS_MODE_NONE, ds, &ds->ds_prev));
1695 
1696 	spa_history_internal_log(LOG_DS_SNAPSHOT, dp->dp_spa, tx, cr,
1697 	    "dataset = %llu", dsobj);
1698 }
1699 
1700 void
1701 dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
1702 {
1703 	ASSERT(dmu_tx_is_syncing(tx));
1704 	ASSERT(ds->ds_user_ptr != NULL);
1705 	ASSERT(ds->ds_phys->ds_next_snap_obj == 0);
1706 
1707 	/*
1708 	 * in case we had to change ds_fsid_guid when we opened it,
1709 	 * sync it out now.
1710 	 */
1711 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
1712 	ds->ds_phys->ds_fsid_guid = ds->ds_fsid_guid;
1713 
1714 	dsl_dir_dirty(ds->ds_dir, tx);
1715 	dmu_objset_sync(ds->ds_user_ptr, zio, tx);
1716 }
1717 
1718 void
1719 dsl_dataset_stats(dsl_dataset_t *ds, nvlist_t *nv)
1720 {
1721 	uint64_t refd, avail, uobjs, aobjs;
1722 
1723 	dsl_dir_stats(ds->ds_dir, nv);
1724 
1725 	dsl_dataset_space(ds, &refd, &avail, &uobjs, &aobjs);
1726 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_AVAILABLE, avail);
1727 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFERENCED, refd);
1728 
1729 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATION,
1730 	    ds->ds_phys->ds_creation_time);
1731 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_CREATETXG,
1732 	    ds->ds_phys->ds_creation_txg);
1733 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFQUOTA,
1734 	    ds->ds_quota);
1735 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_REFRESERVATION,
1736 	    ds->ds_reserved);
1737 
1738 	if (ds->ds_phys->ds_next_snap_obj) {
1739 		/*
1740 		 * This is a snapshot; override the dd's space used with
1741 		 * our unique space and compression ratio.
1742 		 */
1743 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
1744 		    ds->ds_phys->ds_unique_bytes);
1745 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
1746 		    ds->ds_phys->ds_compressed_bytes == 0 ? 100 :
1747 		    (ds->ds_phys->ds_uncompressed_bytes * 100 /
1748 		    ds->ds_phys->ds_compressed_bytes));
1749 	}
1750 }
1751 
1752 void
1753 dsl_dataset_fast_stat(dsl_dataset_t *ds, dmu_objset_stats_t *stat)
1754 {
1755 	stat->dds_creation_txg = ds->ds_phys->ds_creation_txg;
1756 	stat->dds_inconsistent = ds->ds_phys->ds_flags & DS_FLAG_INCONSISTENT;
1757 	stat->dds_guid = ds->ds_phys->ds_guid;
1758 	if (ds->ds_phys->ds_next_snap_obj) {
1759 		stat->dds_is_snapshot = B_TRUE;
1760 		stat->dds_num_clones = ds->ds_phys->ds_num_children - 1;
1761 	}
1762 
1763 	/* clone origin is really a dsl_dir thing... */
1764 	rw_enter(&ds->ds_dir->dd_pool->dp_config_rwlock, RW_READER);
1765 	if (ds->ds_dir->dd_phys->dd_origin_obj) {
1766 		dsl_dataset_t *ods;
1767 
1768 		VERIFY(0 == dsl_dataset_open_obj(ds->ds_dir->dd_pool,
1769 		    ds->ds_dir->dd_phys->dd_origin_obj,
1770 		    NULL, DS_MODE_NONE, FTAG, &ods));
1771 		dsl_dataset_name(ods, stat->dds_origin);
1772 		dsl_dataset_close(ods, DS_MODE_NONE, FTAG);
1773 	}
1774 	rw_exit(&ds->ds_dir->dd_pool->dp_config_rwlock);
1775 }
1776 
1777 uint64_t
1778 dsl_dataset_fsid_guid(dsl_dataset_t *ds)
1779 {
1780 	return (ds->ds_fsid_guid);
1781 }
1782 
1783 void
1784 dsl_dataset_space(dsl_dataset_t *ds,
1785     uint64_t *refdbytesp, uint64_t *availbytesp,
1786     uint64_t *usedobjsp, uint64_t *availobjsp)
1787 {
1788 	*refdbytesp = ds->ds_phys->ds_used_bytes;
1789 	*availbytesp = dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE);
1790 	if (ds->ds_reserved > ds->ds_phys->ds_unique_bytes)
1791 		*availbytesp += ds->ds_reserved - ds->ds_phys->ds_unique_bytes;
1792 	if (ds->ds_quota != 0) {
1793 		/*
1794 		 * Adjust available bytes according to refquota
1795 		 */
1796 		if (*refdbytesp < ds->ds_quota)
1797 			*availbytesp = MIN(*availbytesp,
1798 			    ds->ds_quota - *refdbytesp);
1799 		else
1800 			*availbytesp = 0;
1801 	}
1802 	*usedobjsp = ds->ds_phys->ds_bp.blk_fill;
1803 	*availobjsp = DN_MAX_OBJECT - *usedobjsp;
1804 }
1805 
1806 boolean_t
1807 dsl_dataset_modified_since_lastsnap(dsl_dataset_t *ds)
1808 {
1809 	dsl_pool_t *dp = ds->ds_dir->dd_pool;
1810 
1811 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
1812 	    dsl_pool_sync_context(dp));
1813 	if (ds->ds_prev == NULL)
1814 		return (B_FALSE);
1815 	if (ds->ds_phys->ds_bp.blk_birth >
1816 	    ds->ds_prev->ds_phys->ds_creation_txg)
1817 		return (B_TRUE);
1818 	return (B_FALSE);
1819 }
1820 
1821 /* ARGSUSED */
1822 static int
1823 dsl_dataset_snapshot_rename_check(void *arg1, void *arg2, dmu_tx_t *tx)
1824 {
1825 	dsl_dataset_t *ds = arg1;
1826 	char *newsnapname = arg2;
1827 	dsl_dir_t *dd = ds->ds_dir;
1828 	objset_t *mos = dd->dd_pool->dp_meta_objset;
1829 	dsl_dataset_t *hds;
1830 	uint64_t val;
1831 	int err;
1832 
1833 	err = dsl_dataset_open_obj(dd->dd_pool,
1834 	    dd->dd_phys->dd_head_dataset_obj, NULL, DS_MODE_NONE, FTAG, &hds);
1835 	if (err)
1836 		return (err);
1837 
1838 	/* new name better not be in use */
1839 	err = zap_lookup(mos, hds->ds_phys->ds_snapnames_zapobj,
1840 	    newsnapname, 8, 1, &val);
1841 	dsl_dataset_close(hds, DS_MODE_NONE, FTAG);
1842 
1843 	if (err == 0)
1844 		err = EEXIST;
1845 	else if (err == ENOENT)
1846 		err = 0;
1847 
1848 	/* dataset name + 1 for the "@" + the new snapshot name must fit */
1849 	if (dsl_dir_namelen(ds->ds_dir) + 1 + strlen(newsnapname) >= MAXNAMELEN)
1850 		err = ENAMETOOLONG;
1851 
1852 	return (err);
1853 }
1854 
1855 static void
1856 dsl_dataset_snapshot_rename_sync(void *arg1, void *arg2,
1857     cred_t *cr, dmu_tx_t *tx)
1858 {
1859 	dsl_dataset_t *ds = arg1;
1860 	const char *newsnapname = arg2;
1861 	dsl_dir_t *dd = ds->ds_dir;
1862 	objset_t *mos = dd->dd_pool->dp_meta_objset;
1863 	dsl_dataset_t *hds;
1864 	int err;
1865 
1866 	ASSERT(ds->ds_phys->ds_next_snap_obj != 0);
1867 
1868 	VERIFY(0 == dsl_dataset_open_obj(dd->dd_pool,
1869 	    dd->dd_phys->dd_head_dataset_obj, NULL, DS_MODE_NONE, FTAG, &hds));
1870 
1871 	VERIFY(0 == dsl_dataset_get_snapname(ds));
1872 	err = zap_remove(mos, hds->ds_phys->ds_snapnames_zapobj,
1873 	    ds->ds_snapname, tx);
1874 	ASSERT3U(err, ==, 0);
1875 	mutex_enter(&ds->ds_lock);
1876 	(void) strcpy(ds->ds_snapname, newsnapname);
1877 	mutex_exit(&ds->ds_lock);
1878 	err = zap_add(mos, hds->ds_phys->ds_snapnames_zapobj,
1879 	    ds->ds_snapname, 8, 1, &ds->ds_object, tx);
1880 	ASSERT3U(err, ==, 0);
1881 
1882 	spa_history_internal_log(LOG_DS_RENAME, dd->dd_pool->dp_spa, tx,
1883 	    cr, "dataset = %llu", ds->ds_object);
1884 	dsl_dataset_close(hds, DS_MODE_NONE, FTAG);
1885 }
1886 
1887 struct renamesnaparg {
1888 	dsl_sync_task_group_t *dstg;
1889 	char failed[MAXPATHLEN];
1890 	char *oldsnap;
1891 	char *newsnap;
1892 };
1893 
1894 static int
1895 dsl_snapshot_rename_one(char *name, void *arg)
1896 {
1897 	struct renamesnaparg *ra = arg;
1898 	dsl_dataset_t *ds = NULL;
1899 	char *cp;
1900 	int err;
1901 
1902 	cp = name + strlen(name);
1903 	*cp = '@';
1904 	(void) strcpy(cp + 1, ra->oldsnap);
1905 
1906 	/*
1907 	 * For recursive snapshot renames the parent won't be changing
1908 	 * so we just pass name for both the to/from argument.
1909 	 */
1910 	if (err = zfs_secpolicy_rename_perms(name, name, CRED())) {
1911 		(void) strcpy(ra->failed, name);
1912 		return (err);
1913 	}
1914 
1915 	err = dsl_dataset_open(name, DS_MODE_READONLY | DS_MODE_STANDARD,
1916 	    ra->dstg, &ds);
1917 	if (err == ENOENT) {
1918 		*cp = '\0';
1919 		return (0);
1920 	}
1921 	if (err) {
1922 		(void) strcpy(ra->failed, name);
1923 		*cp = '\0';
1924 		dsl_dataset_close(ds, DS_MODE_STANDARD, ra->dstg);
1925 		return (err);
1926 	}
1927 
1928 #ifdef _KERNEL
1929 	/* for all filesystems undergoing rename, we'll need to unmount it */
1930 	(void) zfs_unmount_snap(name, NULL);
1931 #endif
1932 
1933 	*cp = '\0';
1934 
1935 	dsl_sync_task_create(ra->dstg, dsl_dataset_snapshot_rename_check,
1936 	    dsl_dataset_snapshot_rename_sync, ds, ra->newsnap, 0);
1937 
1938 	return (0);
1939 }
1940 
1941 static int
1942 dsl_recursive_rename(char *oldname, const char *newname)
1943 {
1944 	int err;
1945 	struct renamesnaparg *ra;
1946 	dsl_sync_task_t *dst;
1947 	spa_t *spa;
1948 	char *cp, *fsname = spa_strdup(oldname);
1949 	int len = strlen(oldname);
1950 
1951 	/* truncate the snapshot name to get the fsname */
1952 	cp = strchr(fsname, '@');
1953 	*cp = '\0';
1954 
1955 	err = spa_open(fsname, &spa, FTAG);
1956 	if (err) {
1957 		kmem_free(fsname, len + 1);
1958 		return (err);
1959 	}
1960 	ra = kmem_alloc(sizeof (struct renamesnaparg), KM_SLEEP);
1961 	ra->dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
1962 
1963 	ra->oldsnap = strchr(oldname, '@') + 1;
1964 	ra->newsnap = strchr(newname, '@') + 1;
1965 	*ra->failed = '\0';
1966 
1967 	err = dmu_objset_find(fsname, dsl_snapshot_rename_one, ra,
1968 	    DS_FIND_CHILDREN);
1969 	kmem_free(fsname, len + 1);
1970 
1971 	if (err == 0) {
1972 		err = dsl_sync_task_group_wait(ra->dstg);
1973 	}
1974 
1975 	for (dst = list_head(&ra->dstg->dstg_tasks); dst;
1976 	    dst = list_next(&ra->dstg->dstg_tasks, dst)) {
1977 		dsl_dataset_t *ds = dst->dst_arg1;
1978 		if (dst->dst_err) {
1979 			dsl_dir_name(ds->ds_dir, ra->failed);
1980 			(void) strcat(ra->failed, "@");
1981 			(void) strcat(ra->failed, ra->newsnap);
1982 		}
1983 		dsl_dataset_close(ds, DS_MODE_STANDARD, ra->dstg);
1984 	}
1985 
1986 	if (err)
1987 		(void) strcpy(oldname, ra->failed);
1988 
1989 	dsl_sync_task_group_destroy(ra->dstg);
1990 	kmem_free(ra, sizeof (struct renamesnaparg));
1991 	spa_close(spa, FTAG);
1992 	return (err);
1993 }
1994 
1995 static int
1996 dsl_valid_rename(char *oldname, void *arg)
1997 {
1998 	int delta = *(int *)arg;
1999 
2000 	if (strlen(oldname) + delta >= MAXNAMELEN)
2001 		return (ENAMETOOLONG);
2002 
2003 	return (0);
2004 }
2005 
2006 #pragma weak dmu_objset_rename = dsl_dataset_rename
2007 int
2008 dsl_dataset_rename(char *oldname, const char *newname,
2009     boolean_t recursive)
2010 {
2011 	dsl_dir_t *dd;
2012 	dsl_dataset_t *ds;
2013 	const char *tail;
2014 	int err;
2015 
2016 	err = dsl_dir_open(oldname, FTAG, &dd, &tail);
2017 	if (err)
2018 		return (err);
2019 	if (tail == NULL) {
2020 		int delta = strlen(newname) - strlen(oldname);
2021 
2022 		/* if we're growing, validate child size lengths */
2023 		if (delta > 0)
2024 			err = dmu_objset_find(oldname, dsl_valid_rename,
2025 			    &delta, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
2026 
2027 		if (!err)
2028 			err = dsl_dir_rename(dd, newname);
2029 		dsl_dir_close(dd, FTAG);
2030 		return (err);
2031 	}
2032 	if (tail[0] != '@') {
2033 		/* the name ended in a nonexistant component */
2034 		dsl_dir_close(dd, FTAG);
2035 		return (ENOENT);
2036 	}
2037 
2038 	dsl_dir_close(dd, FTAG);
2039 
2040 	/* new name must be snapshot in same filesystem */
2041 	tail = strchr(newname, '@');
2042 	if (tail == NULL)
2043 		return (EINVAL);
2044 	tail++;
2045 	if (strncmp(oldname, newname, tail - newname) != 0)
2046 		return (EXDEV);
2047 
2048 	if (recursive) {
2049 		err = dsl_recursive_rename(oldname, newname);
2050 	} else {
2051 		err = dsl_dataset_open(oldname,
2052 		    DS_MODE_READONLY | DS_MODE_STANDARD, FTAG, &ds);
2053 		if (err)
2054 			return (err);
2055 
2056 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2057 		    dsl_dataset_snapshot_rename_check,
2058 		    dsl_dataset_snapshot_rename_sync, ds, (char *)tail, 1);
2059 
2060 		dsl_dataset_close(ds, DS_MODE_STANDARD, FTAG);
2061 	}
2062 
2063 	return (err);
2064 }
2065 
2066 struct promotearg {
2067 	uint64_t used, comp, uncomp, unique;
2068 	uint64_t newnext_obj, snapnames_obj;
2069 };
2070 
2071 /* ARGSUSED */
2072 static int
2073 dsl_dataset_promote_check(void *arg1, void *arg2, dmu_tx_t *tx)
2074 {
2075 	dsl_dataset_t *hds = arg1;
2076 	struct promotearg *pa = arg2;
2077 	dsl_dir_t *dd = hds->ds_dir;
2078 	dsl_pool_t *dp = hds->ds_dir->dd_pool;
2079 	dsl_dir_t *odd = NULL;
2080 	dsl_dataset_t *ds = NULL;
2081 	dsl_dataset_t *origin_ds = NULL;
2082 	dsl_dataset_t *newnext_ds = NULL;
2083 	int err;
2084 	char *name = NULL;
2085 	uint64_t itor = 0;
2086 	blkptr_t bp;
2087 
2088 	bzero(pa, sizeof (*pa));
2089 
2090 	/* Check that it is a clone */
2091 	if (dd->dd_phys->dd_origin_obj == 0)
2092 		return (EINVAL);
2093 
2094 	/* Since this is so expensive, don't do the preliminary check */
2095 	if (!dmu_tx_is_syncing(tx))
2096 		return (0);
2097 
2098 	if (err = dsl_dataset_open_obj(dp, dd->dd_phys->dd_origin_obj,
2099 	    NULL, DS_MODE_EXCLUSIVE, FTAG, &origin_ds))
2100 		goto out;
2101 	odd = origin_ds->ds_dir;
2102 
2103 	{
2104 		dsl_dataset_t *phds;
2105 		if (err = dsl_dataset_open_obj(dd->dd_pool,
2106 		    odd->dd_phys->dd_head_dataset_obj,
2107 		    NULL, DS_MODE_NONE, FTAG, &phds))
2108 			goto out;
2109 		pa->snapnames_obj = phds->ds_phys->ds_snapnames_zapobj;
2110 		dsl_dataset_close(phds, DS_MODE_NONE, FTAG);
2111 	}
2112 
2113 	if (hds->ds_phys->ds_flags & DS_FLAG_NOPROMOTE) {
2114 		err = EXDEV;
2115 		goto out;
2116 	}
2117 
2118 	/* find origin's new next ds */
2119 	VERIFY(0 == dsl_dataset_open_obj(dd->dd_pool, hds->ds_object,
2120 	    NULL, DS_MODE_NONE, FTAG, &newnext_ds));
2121 	while (newnext_ds->ds_phys->ds_prev_snap_obj != origin_ds->ds_object) {
2122 		dsl_dataset_t *prev;
2123 
2124 		if (err = dsl_dataset_open_obj(dd->dd_pool,
2125 		    newnext_ds->ds_phys->ds_prev_snap_obj,
2126 		    NULL, DS_MODE_NONE, FTAG, &prev))
2127 			goto out;
2128 		dsl_dataset_close(newnext_ds, DS_MODE_NONE, FTAG);
2129 		newnext_ds = prev;
2130 	}
2131 	pa->newnext_obj = newnext_ds->ds_object;
2132 
2133 	/* compute origin's new unique space */
2134 	while ((err = bplist_iterate(&newnext_ds->ds_deadlist,
2135 	    &itor, &bp)) == 0) {
2136 		if (bp.blk_birth > origin_ds->ds_phys->ds_prev_snap_txg)
2137 			pa->unique += bp_get_dasize(dd->dd_pool->dp_spa, &bp);
2138 	}
2139 	if (err != ENOENT)
2140 		goto out;
2141 
2142 	/* Walk the snapshots that we are moving */
2143 	name = kmem_alloc(MAXPATHLEN, KM_SLEEP);
2144 	ds = origin_ds;
2145 	/* CONSTCOND */
2146 	while (TRUE) {
2147 		uint64_t val, dlused, dlcomp, dluncomp;
2148 		dsl_dataset_t *prev;
2149 
2150 		/* Check that the snapshot name does not conflict */
2151 		dsl_dataset_name(ds, name);
2152 		err = zap_lookup(dd->dd_pool->dp_meta_objset,
2153 		    hds->ds_phys->ds_snapnames_zapobj, ds->ds_snapname,
2154 		    8, 1, &val);
2155 		if (err != ENOENT) {
2156 			if (err == 0)
2157 				err = EEXIST;
2158 			goto out;
2159 		}
2160 
2161 		/*
2162 		 * compute space to transfer.  Each snapshot gave birth to:
2163 		 * (my used) - (prev's used) + (deadlist's used)
2164 		 */
2165 		pa->used += ds->ds_phys->ds_used_bytes;
2166 		pa->comp += ds->ds_phys->ds_compressed_bytes;
2167 		pa->uncomp += ds->ds_phys->ds_uncompressed_bytes;
2168 
2169 		/* If we reach the first snapshot, we're done. */
2170 		if (ds->ds_phys->ds_prev_snap_obj == 0)
2171 			break;
2172 
2173 		if (err = bplist_space(&ds->ds_deadlist,
2174 		    &dlused, &dlcomp, &dluncomp))
2175 			goto out;
2176 		if (err = dsl_dataset_open_obj(dd->dd_pool,
2177 		    ds->ds_phys->ds_prev_snap_obj, NULL, DS_MODE_EXCLUSIVE,
2178 		    FTAG, &prev))
2179 			goto out;
2180 		pa->used += dlused - prev->ds_phys->ds_used_bytes;
2181 		pa->comp += dlcomp - prev->ds_phys->ds_compressed_bytes;
2182 		pa->uncomp += dluncomp - prev->ds_phys->ds_uncompressed_bytes;
2183 
2184 		/*
2185 		 * We could be a clone of a clone.  If we reach our
2186 		 * parent's branch point, we're done.
2187 		 */
2188 		if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
2189 			dsl_dataset_close(prev, DS_MODE_EXCLUSIVE, FTAG);
2190 			break;
2191 		}
2192 		if (ds != origin_ds)
2193 			dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2194 		ds = prev;
2195 	}
2196 
2197 	/* Check that there is enough space here */
2198 	err = dsl_dir_transfer_possible(odd, dd, pa->used);
2199 
2200 out:
2201 	if (ds && ds != origin_ds)
2202 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2203 	if (origin_ds)
2204 		dsl_dataset_close(origin_ds, DS_MODE_EXCLUSIVE, FTAG);
2205 	if (newnext_ds)
2206 		dsl_dataset_close(newnext_ds, DS_MODE_NONE, FTAG);
2207 	if (name)
2208 		kmem_free(name, MAXPATHLEN);
2209 	return (err);
2210 }
2211 
2212 static void
2213 dsl_dataset_promote_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
2214 {
2215 	dsl_dataset_t *hds = arg1;
2216 	struct promotearg *pa = arg2;
2217 	dsl_dir_t *dd = hds->ds_dir;
2218 	dsl_pool_t *dp = hds->ds_dir->dd_pool;
2219 	dsl_dir_t *odd = NULL;
2220 	dsl_dataset_t *ds, *origin_ds;
2221 	char *name;
2222 
2223 	ASSERT(dd->dd_phys->dd_origin_obj != 0);
2224 	ASSERT(0 == (hds->ds_phys->ds_flags & DS_FLAG_NOPROMOTE));
2225 
2226 	VERIFY(0 == dsl_dataset_open_obj(dp, dd->dd_phys->dd_origin_obj,
2227 	    NULL, DS_MODE_EXCLUSIVE, FTAG, &origin_ds));
2228 	/*
2229 	 * We need to explicitly open odd, since origin_ds's dd will be
2230 	 * changing.
2231 	 */
2232 	VERIFY(0 == dsl_dir_open_obj(dp, origin_ds->ds_dir->dd_object,
2233 	    NULL, FTAG, &odd));
2234 
2235 	/* move snapshots to this dir */
2236 	name = kmem_alloc(MAXPATHLEN, KM_SLEEP);
2237 	ds = origin_ds;
2238 	/* CONSTCOND */
2239 	while (TRUE) {
2240 		dsl_dataset_t *prev;
2241 
2242 		/* move snap name entry */
2243 		dsl_dataset_name(ds, name);
2244 		VERIFY(0 == zap_remove(dp->dp_meta_objset,
2245 		    pa->snapnames_obj, ds->ds_snapname, tx));
2246 		VERIFY(0 == zap_add(dp->dp_meta_objset,
2247 		    hds->ds_phys->ds_snapnames_zapobj, ds->ds_snapname,
2248 		    8, 1, &ds->ds_object, tx));
2249 
2250 		/* change containing dsl_dir */
2251 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
2252 		ASSERT3U(ds->ds_phys->ds_dir_obj, ==, odd->dd_object);
2253 		ds->ds_phys->ds_dir_obj = dd->dd_object;
2254 		ASSERT3P(ds->ds_dir, ==, odd);
2255 		dsl_dir_close(ds->ds_dir, ds);
2256 		VERIFY(0 == dsl_dir_open_obj(dp, dd->dd_object,
2257 		    NULL, ds, &ds->ds_dir));
2258 
2259 		ASSERT3U(dsl_prop_numcb(ds), ==, 0);
2260 
2261 		if (ds->ds_phys->ds_prev_snap_obj == 0)
2262 			break;
2263 
2264 		VERIFY(0 == dsl_dataset_open_obj(dp,
2265 		    ds->ds_phys->ds_prev_snap_obj, NULL, DS_MODE_EXCLUSIVE,
2266 		    FTAG, &prev));
2267 
2268 		if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
2269 			dsl_dataset_close(prev, DS_MODE_EXCLUSIVE, FTAG);
2270 			break;
2271 		}
2272 		if (ds != origin_ds)
2273 			dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2274 		ds = prev;
2275 	}
2276 	if (ds != origin_ds)
2277 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
2278 
2279 	/* change origin's next snap */
2280 	dmu_buf_will_dirty(origin_ds->ds_dbuf, tx);
2281 	origin_ds->ds_phys->ds_next_snap_obj = pa->newnext_obj;
2282 
2283 	/* change origin */
2284 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
2285 	ASSERT3U(dd->dd_phys->dd_origin_obj, ==, origin_ds->ds_object);
2286 	dd->dd_phys->dd_origin_obj = odd->dd_phys->dd_origin_obj;
2287 	dmu_buf_will_dirty(odd->dd_dbuf, tx);
2288 	odd->dd_phys->dd_origin_obj = origin_ds->ds_object;
2289 
2290 	/* change space accounting */
2291 	dsl_dir_diduse_space(odd, -pa->used, -pa->comp, -pa->uncomp, tx);
2292 	dsl_dir_diduse_space(dd, pa->used, pa->comp, pa->uncomp, tx);
2293 	origin_ds->ds_phys->ds_unique_bytes = pa->unique;
2294 
2295 	/* log history record */
2296 	spa_history_internal_log(LOG_DS_PROMOTE, dd->dd_pool->dp_spa, tx,
2297 	    cr, "dataset = %llu", ds->ds_object);
2298 
2299 	dsl_dir_close(odd, FTAG);
2300 	dsl_dataset_close(origin_ds, DS_MODE_EXCLUSIVE, FTAG);
2301 	kmem_free(name, MAXPATHLEN);
2302 }
2303 
2304 int
2305 dsl_dataset_promote(const char *name)
2306 {
2307 	dsl_dataset_t *ds;
2308 	int err;
2309 	dmu_object_info_t doi;
2310 	struct promotearg pa;
2311 
2312 	err = dsl_dataset_open(name, DS_MODE_NONE, FTAG, &ds);
2313 	if (err)
2314 		return (err);
2315 
2316 	err = dmu_object_info(ds->ds_dir->dd_pool->dp_meta_objset,
2317 	    ds->ds_phys->ds_snapnames_zapobj, &doi);
2318 	if (err) {
2319 		dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
2320 		return (err);
2321 	}
2322 
2323 	/*
2324 	 * Add in 128x the snapnames zapobj size, since we will be moving
2325 	 * a bunch of snapnames to the promoted ds, and dirtying their
2326 	 * bonus buffers.
2327 	 */
2328 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2329 	    dsl_dataset_promote_check,
2330 	    dsl_dataset_promote_sync, ds, &pa, 2 + 2 * doi.doi_physical_blks);
2331 	dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
2332 	return (err);
2333 }
2334 
2335 struct cloneswaparg {
2336 	dsl_dataset_t *cds; /* clone dataset */
2337 	dsl_dataset_t *ohds; /* origin's head dataset */
2338 	boolean_t force;
2339 	int64_t unused_refres_delta; /* change in unconsumed refreservation */
2340 };
2341 
2342 /* ARGSUSED */
2343 static int
2344 dsl_dataset_clone_swap_check(void *arg1, void *arg2, dmu_tx_t *tx)
2345 {
2346 	struct cloneswaparg *csa = arg1;
2347 
2348 	/* they should both be heads */
2349 	if (dsl_dataset_is_snapshot(csa->cds) ||
2350 	    dsl_dataset_is_snapshot(csa->ohds))
2351 		return (EINVAL);
2352 
2353 	/* the branch point should be just before them */
2354 	if (csa->cds->ds_prev != csa->ohds->ds_prev)
2355 		return (EINVAL);
2356 
2357 	/* cds should be the clone */
2358 	if (csa->cds->ds_prev->ds_phys->ds_next_snap_obj !=
2359 	    csa->ohds->ds_object)
2360 		return (EINVAL);
2361 
2362 	/* the clone should be a child of the origin */
2363 	if (csa->cds->ds_dir->dd_parent != csa->ohds->ds_dir)
2364 		return (EINVAL);
2365 
2366 	/* ohds shouldn't be modified unless 'force' */
2367 	if (!csa->force && dsl_dataset_modified_since_lastsnap(csa->ohds))
2368 		return (ETXTBSY);
2369 
2370 	/* adjust amount of any unconsumed refreservation */
2371 	csa->unused_refres_delta =
2372 	    (int64_t)MIN(csa->ohds->ds_reserved,
2373 	    csa->ohds->ds_phys->ds_unique_bytes) -
2374 	    (int64_t)MIN(csa->ohds->ds_reserved,
2375 	    csa->cds->ds_phys->ds_unique_bytes);
2376 
2377 	if (csa->unused_refres_delta > 0 &&
2378 	    csa->unused_refres_delta >
2379 	    dsl_dir_space_available(csa->ohds->ds_dir, NULL, 0, TRUE))
2380 		return (ENOSPC);
2381 
2382 	return (0);
2383 }
2384 
2385 /* ARGSUSED */
2386 static void
2387 dsl_dataset_clone_swap_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
2388 {
2389 	struct cloneswaparg *csa = arg1;
2390 	dsl_pool_t *dp = csa->cds->ds_dir->dd_pool;
2391 	uint64_t itor = 0;
2392 	blkptr_t bp;
2393 	uint64_t unique = 0;
2394 	int err;
2395 
2396 	ASSERT(csa->cds->ds_reserved == 0);
2397 	ASSERT(csa->cds->ds_quota == csa->ohds->ds_quota);
2398 
2399 	dmu_buf_will_dirty(csa->cds->ds_dbuf, tx);
2400 	dmu_buf_will_dirty(csa->ohds->ds_dbuf, tx);
2401 	dmu_buf_will_dirty(csa->cds->ds_prev->ds_dbuf, tx);
2402 
2403 	if (csa->cds->ds_user_ptr != NULL) {
2404 		csa->cds->ds_user_evict_func(csa->cds, csa->cds->ds_user_ptr);
2405 		csa->cds->ds_user_ptr = NULL;
2406 	}
2407 
2408 	if (csa->ohds->ds_user_ptr != NULL) {
2409 		csa->ohds->ds_user_evict_func(csa->ohds,
2410 		    csa->ohds->ds_user_ptr);
2411 		csa->ohds->ds_user_ptr = NULL;
2412 	}
2413 
2414 	/* compute unique space */
2415 	while ((err = bplist_iterate(&csa->cds->ds_deadlist,
2416 	    &itor, &bp)) == 0) {
2417 		if (bp.blk_birth > csa->cds->ds_prev->ds_phys->ds_prev_snap_txg)
2418 			unique += bp_get_dasize(dp->dp_spa, &bp);
2419 	}
2420 	VERIFY(err == ENOENT);
2421 
2422 	/* reset origin's unique bytes */
2423 	csa->cds->ds_prev->ds_phys->ds_unique_bytes = unique;
2424 
2425 	/* swap blkptrs */
2426 	{
2427 		blkptr_t tmp;
2428 		tmp = csa->ohds->ds_phys->ds_bp;
2429 		csa->ohds->ds_phys->ds_bp = csa->cds->ds_phys->ds_bp;
2430 		csa->cds->ds_phys->ds_bp = tmp;
2431 	}
2432 
2433 	/* set dd_*_bytes */
2434 	{
2435 		int64_t dused, dcomp, duncomp;
2436 		uint64_t cdl_used, cdl_comp, cdl_uncomp;
2437 		uint64_t odl_used, odl_comp, odl_uncomp;
2438 
2439 		VERIFY(0 == bplist_space(&csa->cds->ds_deadlist, &cdl_used,
2440 		    &cdl_comp, &cdl_uncomp));
2441 		VERIFY(0 == bplist_space(&csa->ohds->ds_deadlist, &odl_used,
2442 		    &odl_comp, &odl_uncomp));
2443 		dused = csa->cds->ds_phys->ds_used_bytes + cdl_used -
2444 		    (csa->ohds->ds_phys->ds_used_bytes + odl_used);
2445 		dcomp = csa->cds->ds_phys->ds_compressed_bytes + cdl_comp -
2446 		    (csa->ohds->ds_phys->ds_compressed_bytes + odl_comp);
2447 		duncomp = csa->cds->ds_phys->ds_uncompressed_bytes +
2448 		    cdl_uncomp -
2449 		    (csa->ohds->ds_phys->ds_uncompressed_bytes + odl_uncomp);
2450 
2451 		dsl_dir_diduse_space(csa->ohds->ds_dir,
2452 		    dused, dcomp, duncomp, tx);
2453 		dsl_dir_diduse_space(csa->cds->ds_dir,
2454 		    -dused, -dcomp, -duncomp, tx);
2455 	}
2456 
2457 #define	SWITCH64(x, y) \
2458 	{ \
2459 		uint64_t __tmp = (x); \
2460 		(x) = (y); \
2461 		(y) = __tmp; \
2462 	}
2463 
2464 	/* swap ds_*_bytes */
2465 	SWITCH64(csa->ohds->ds_phys->ds_used_bytes,
2466 	    csa->cds->ds_phys->ds_used_bytes);
2467 	SWITCH64(csa->ohds->ds_phys->ds_compressed_bytes,
2468 	    csa->cds->ds_phys->ds_compressed_bytes);
2469 	SWITCH64(csa->ohds->ds_phys->ds_uncompressed_bytes,
2470 	    csa->cds->ds_phys->ds_uncompressed_bytes);
2471 	SWITCH64(csa->ohds->ds_phys->ds_unique_bytes,
2472 	    csa->cds->ds_phys->ds_unique_bytes);
2473 
2474 	/* apply any parent delta for change in unconsumed refreservation */
2475 	dsl_dir_diduse_space(csa->ohds->ds_dir, csa->unused_refres_delta,
2476 	    0, 0, tx);
2477 
2478 	/* swap deadlists */
2479 	bplist_close(&csa->cds->ds_deadlist);
2480 	bplist_close(&csa->ohds->ds_deadlist);
2481 	SWITCH64(csa->ohds->ds_phys->ds_deadlist_obj,
2482 	    csa->cds->ds_phys->ds_deadlist_obj);
2483 	VERIFY(0 == bplist_open(&csa->cds->ds_deadlist, dp->dp_meta_objset,
2484 	    csa->cds->ds_phys->ds_deadlist_obj));
2485 	VERIFY(0 == bplist_open(&csa->ohds->ds_deadlist, dp->dp_meta_objset,
2486 	    csa->ohds->ds_phys->ds_deadlist_obj));
2487 }
2488 
2489 /*
2490  * Swap 'clone' with its origin head file system.
2491  */
2492 int
2493 dsl_dataset_clone_swap(dsl_dataset_t *clone, dsl_dataset_t *origin_head,
2494     boolean_t force)
2495 {
2496 	struct cloneswaparg csa;
2497 
2498 	ASSERT(clone->ds_open_refcount == DS_REF_MAX);
2499 	ASSERT(origin_head->ds_open_refcount == DS_REF_MAX);
2500 
2501 	csa.cds = clone;
2502 	csa.ohds = origin_head;
2503 	csa.force = force;
2504 	return (dsl_sync_task_do(clone->ds_dir->dd_pool,
2505 	    dsl_dataset_clone_swap_check,
2506 	    dsl_dataset_clone_swap_sync, &csa, NULL, 9));
2507 }
2508 
2509 /*
2510  * Given a pool name and a dataset object number in that pool,
2511  * return the name of that dataset.
2512  */
2513 int
2514 dsl_dsobj_to_dsname(char *pname, uint64_t obj, char *buf)
2515 {
2516 	spa_t *spa;
2517 	dsl_pool_t *dp;
2518 	dsl_dataset_t *ds = NULL;
2519 	int error;
2520 
2521 	if ((error = spa_open(pname, &spa, FTAG)) != 0)
2522 		return (error);
2523 	dp = spa_get_dsl(spa);
2524 	rw_enter(&dp->dp_config_rwlock, RW_READER);
2525 	if ((error = dsl_dataset_open_obj(dp, obj,
2526 	    NULL, DS_MODE_NONE, FTAG, &ds)) != 0) {
2527 		rw_exit(&dp->dp_config_rwlock);
2528 		spa_close(spa, FTAG);
2529 		return (error);
2530 	}
2531 	dsl_dataset_name(ds, buf);
2532 	dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
2533 	rw_exit(&dp->dp_config_rwlock);
2534 	spa_close(spa, FTAG);
2535 
2536 	return (0);
2537 }
2538 
2539 int
2540 dsl_dataset_check_quota(dsl_dataset_t *ds, boolean_t check_quota,
2541     uint64_t asize, uint64_t inflight, uint64_t *used)
2542 {
2543 	int error = 0;
2544 
2545 	ASSERT3S(asize, >, 0);
2546 
2547 	mutex_enter(&ds->ds_lock);
2548 	/*
2549 	 * Make a space adjustment for reserved bytes.
2550 	 */
2551 	if (ds->ds_reserved > ds->ds_phys->ds_unique_bytes) {
2552 		ASSERT3U(*used, >=,
2553 		    ds->ds_reserved - ds->ds_phys->ds_unique_bytes);
2554 		*used -= (ds->ds_reserved - ds->ds_phys->ds_unique_bytes);
2555 	}
2556 
2557 	if (!check_quota || ds->ds_quota == 0) {
2558 		mutex_exit(&ds->ds_lock);
2559 		return (0);
2560 	}
2561 	/*
2562 	 * If they are requesting more space, and our current estimate
2563 	 * is over quota, they get to try again unless the actual
2564 	 * on-disk is over quota and there are no pending changes (which
2565 	 * may free up space for us).
2566 	 */
2567 	if (ds->ds_phys->ds_used_bytes + inflight >= ds->ds_quota) {
2568 		if (inflight > 0 || ds->ds_phys->ds_used_bytes < ds->ds_quota)
2569 			error = ERESTART;
2570 		else
2571 			error = EDQUOT;
2572 	}
2573 	mutex_exit(&ds->ds_lock);
2574 
2575 	return (error);
2576 }
2577 
2578 /* ARGSUSED */
2579 static int
2580 dsl_dataset_set_quota_check(void *arg1, void *arg2, dmu_tx_t *tx)
2581 {
2582 	dsl_dataset_t *ds = arg1;
2583 	uint64_t *quotap = arg2;
2584 	uint64_t new_quota = *quotap;
2585 
2586 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) < SPA_VERSION_REFQUOTA)
2587 		return (ENOTSUP);
2588 
2589 	if (new_quota == 0)
2590 		return (0);
2591 
2592 	if (new_quota < ds->ds_phys->ds_used_bytes ||
2593 	    new_quota < ds->ds_reserved)
2594 		return (ENOSPC);
2595 
2596 	return (0);
2597 }
2598 
2599 /* ARGSUSED */
2600 void
2601 dsl_dataset_set_quota_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
2602 {
2603 	dsl_dataset_t *ds = arg1;
2604 	uint64_t *quotap = arg2;
2605 	uint64_t new_quota = *quotap;
2606 
2607 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
2608 
2609 	mutex_enter(&ds->ds_lock);
2610 	ds->ds_quota = new_quota;
2611 	mutex_exit(&ds->ds_lock);
2612 
2613 	dsl_prop_set_uint64_sync(ds->ds_dir, "refquota", new_quota, cr, tx);
2614 
2615 	spa_history_internal_log(LOG_DS_REFQUOTA, ds->ds_dir->dd_pool->dp_spa,
2616 	    tx, cr, "%lld dataset = %llu ",
2617 	    (longlong_t)new_quota, ds->ds_dir->dd_phys->dd_head_dataset_obj);
2618 }
2619 
2620 int
2621 dsl_dataset_set_quota(const char *dsname, uint64_t quota)
2622 {
2623 	dsl_dataset_t *ds;
2624 	int err;
2625 
2626 	err = dsl_dataset_open(dsname, DS_MODE_STANDARD, FTAG, &ds);
2627 	if (err)
2628 		return (err);
2629 
2630 	if (quota != ds->ds_quota) {
2631 		/*
2632 		 * If someone removes a file, then tries to set the quota, we
2633 		 * want to make sure the file freeing takes effect.
2634 		 */
2635 		txg_wait_open(ds->ds_dir->dd_pool, 0);
2636 
2637 		err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2638 		    dsl_dataset_set_quota_check, dsl_dataset_set_quota_sync,
2639 		    ds, &quota, 0);
2640 	}
2641 	dsl_dataset_close(ds, DS_MODE_STANDARD, FTAG);
2642 	return (err);
2643 }
2644 
2645 static int
2646 dsl_dataset_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
2647 {
2648 	dsl_dataset_t *ds = arg1;
2649 	uint64_t *reservationp = arg2;
2650 	uint64_t new_reservation = *reservationp;
2651 	int64_t delta;
2652 	uint64_t unique;
2653 
2654 	if (new_reservation > INT64_MAX)
2655 		return (EOVERFLOW);
2656 
2657 	if (spa_version(ds->ds_dir->dd_pool->dp_spa) <
2658 	    SPA_VERSION_REFRESERVATION)
2659 		return (ENOTSUP);
2660 
2661 	if (dsl_dataset_is_snapshot(ds))
2662 		return (EINVAL);
2663 
2664 	/*
2665 	 * If we are doing the preliminary check in open context, the
2666 	 * space estimates may be inaccurate.
2667 	 */
2668 	if (!dmu_tx_is_syncing(tx))
2669 		return (0);
2670 
2671 	mutex_enter(&ds->ds_lock);
2672 	unique = dsl_dataset_unique(ds);
2673 	delta = MAX(unique, new_reservation) - MAX(unique, ds->ds_reserved);
2674 	mutex_exit(&ds->ds_lock);
2675 
2676 	if (delta > 0 &&
2677 	    delta > dsl_dir_space_available(ds->ds_dir, NULL, 0, TRUE))
2678 		return (ENOSPC);
2679 	if (delta > 0 && ds->ds_quota > 0 &&
2680 	    new_reservation > ds->ds_quota)
2681 		return (ENOSPC);
2682 
2683 	return (0);
2684 }
2685 
2686 /* ARGSUSED */
2687 static void
2688 dsl_dataset_set_reservation_sync(void *arg1, void *arg2, cred_t *cr,
2689     dmu_tx_t *tx)
2690 {
2691 	dsl_dataset_t *ds = arg1;
2692 	uint64_t *reservationp = arg2;
2693 	uint64_t new_reservation = *reservationp;
2694 	uint64_t unique;
2695 	int64_t delta;
2696 
2697 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
2698 
2699 	mutex_enter(&ds->ds_lock);
2700 	unique = dsl_dataset_unique(ds);
2701 	delta = MAX(0, (int64_t)(new_reservation - unique)) -
2702 	    MAX(0, (int64_t)(ds->ds_reserved - unique));
2703 	ds->ds_reserved = new_reservation;
2704 	mutex_exit(&ds->ds_lock);
2705 
2706 	dsl_prop_set_uint64_sync(ds->ds_dir, "refreservation",
2707 	    new_reservation, cr, tx);
2708 
2709 	dsl_dir_diduse_space(ds->ds_dir, delta, 0, 0, tx);
2710 
2711 	spa_history_internal_log(LOG_DS_REFRESERV,
2712 	    ds->ds_dir->dd_pool->dp_spa, tx, cr, "%lld dataset = %llu",
2713 	    (longlong_t)new_reservation,
2714 	    ds->ds_dir->dd_phys->dd_head_dataset_obj);
2715 }
2716 
2717 int
2718 dsl_dataset_set_reservation(const char *dsname, uint64_t reservation)
2719 {
2720 	dsl_dataset_t *ds;
2721 	int err;
2722 
2723 	err = dsl_dataset_open(dsname, DS_MODE_STANDARD, FTAG, &ds);
2724 	if (err)
2725 		return (err);
2726 
2727 	err = dsl_sync_task_do(ds->ds_dir->dd_pool,
2728 	    dsl_dataset_set_reservation_check,
2729 	    dsl_dataset_set_reservation_sync, ds, &reservation, 0);
2730 	dsl_dataset_close(ds, DS_MODE_STANDARD, FTAG);
2731 	return (err);
2732 }
2733