xref: /illumos-gate/usr/src/uts/common/fs/zfs/dmu_objset.c (revision 07a48826732249fcd3aa8dd53c8389595e9f1fbc)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #include <sys/cred.h>
27 #include <sys/zfs_context.h>
28 #include <sys/dmu_objset.h>
29 #include <sys/dsl_dir.h>
30 #include <sys/dsl_dataset.h>
31 #include <sys/dsl_prop.h>
32 #include <sys/dsl_pool.h>
33 #include <sys/dsl_synctask.h>
34 #include <sys/dsl_deleg.h>
35 #include <sys/dnode.h>
36 #include <sys/dbuf.h>
37 #include <sys/zvol.h>
38 #include <sys/dmu_tx.h>
39 #include <sys/zio_checksum.h>
40 #include <sys/zap.h>
41 #include <sys/zil.h>
42 #include <sys/dmu_impl.h>
43 #include <sys/zfs_ioctl.h>
44 
45 spa_t *
46 dmu_objset_spa(objset_t *os)
47 {
48 	return (os->os->os_spa);
49 }
50 
51 zilog_t *
52 dmu_objset_zil(objset_t *os)
53 {
54 	return (os->os->os_zil);
55 }
56 
57 dsl_pool_t *
58 dmu_objset_pool(objset_t *os)
59 {
60 	dsl_dataset_t *ds;
61 
62 	if ((ds = os->os->os_dsl_dataset) != NULL && ds->ds_dir)
63 		return (ds->ds_dir->dd_pool);
64 	else
65 		return (spa_get_dsl(os->os->os_spa));
66 }
67 
68 dsl_dataset_t *
69 dmu_objset_ds(objset_t *os)
70 {
71 	return (os->os->os_dsl_dataset);
72 }
73 
74 dmu_objset_type_t
75 dmu_objset_type(objset_t *os)
76 {
77 	return (os->os->os_phys->os_type);
78 }
79 
80 void
81 dmu_objset_name(objset_t *os, char *buf)
82 {
83 	dsl_dataset_name(os->os->os_dsl_dataset, buf);
84 }
85 
86 uint64_t
87 dmu_objset_id(objset_t *os)
88 {
89 	dsl_dataset_t *ds = os->os->os_dsl_dataset;
90 
91 	return (ds ? ds->ds_object : 0);
92 }
93 
94 static void
95 checksum_changed_cb(void *arg, uint64_t newval)
96 {
97 	objset_impl_t *osi = arg;
98 
99 	/*
100 	 * Inheritance should have been done by now.
101 	 */
102 	ASSERT(newval != ZIO_CHECKSUM_INHERIT);
103 
104 	osi->os_checksum = zio_checksum_select(newval, ZIO_CHECKSUM_ON_VALUE);
105 }
106 
107 static void
108 compression_changed_cb(void *arg, uint64_t newval)
109 {
110 	objset_impl_t *osi = arg;
111 
112 	/*
113 	 * Inheritance and range checking should have been done by now.
114 	 */
115 	ASSERT(newval != ZIO_COMPRESS_INHERIT);
116 
117 	osi->os_compress = zio_compress_select(newval, ZIO_COMPRESS_ON_VALUE);
118 }
119 
120 static void
121 copies_changed_cb(void *arg, uint64_t newval)
122 {
123 	objset_impl_t *osi = arg;
124 
125 	/*
126 	 * Inheritance and range checking should have been done by now.
127 	 */
128 	ASSERT(newval > 0);
129 	ASSERT(newval <= spa_max_replication(osi->os_spa));
130 
131 	osi->os_copies = newval;
132 }
133 
134 static void
135 primary_cache_changed_cb(void *arg, uint64_t newval)
136 {
137 	objset_impl_t *osi = arg;
138 
139 	/*
140 	 * Inheritance and range checking should have been done by now.
141 	 */
142 	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
143 	    newval == ZFS_CACHE_METADATA);
144 
145 	osi->os_primary_cache = newval;
146 }
147 
148 static void
149 secondary_cache_changed_cb(void *arg, uint64_t newval)
150 {
151 	objset_impl_t *osi = arg;
152 
153 	/*
154 	 * Inheritance and range checking should have been done by now.
155 	 */
156 	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
157 	    newval == ZFS_CACHE_METADATA);
158 
159 	osi->os_secondary_cache = newval;
160 }
161 
162 void
163 dmu_objset_byteswap(void *buf, size_t size)
164 {
165 	objset_phys_t *osp = buf;
166 
167 	ASSERT(size == OBJSET_OLD_PHYS_SIZE || size == sizeof (objset_phys_t));
168 	dnode_byteswap(&osp->os_meta_dnode);
169 	byteswap_uint64_array(&osp->os_zil_header, sizeof (zil_header_t));
170 	osp->os_type = BSWAP_64(osp->os_type);
171 	osp->os_flags = BSWAP_64(osp->os_flags);
172 	if (size == sizeof (objset_phys_t)) {
173 		dnode_byteswap(&osp->os_userused_dnode);
174 		dnode_byteswap(&osp->os_groupused_dnode);
175 	}
176 }
177 
178 int
179 dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
180     objset_impl_t **osip)
181 {
182 	objset_impl_t *osi;
183 	int i, err;
184 
185 	ASSERT(ds == NULL || MUTEX_HELD(&ds->ds_opening_lock));
186 
187 	osi = kmem_zalloc(sizeof (objset_impl_t), KM_SLEEP);
188 	osi->os.os = osi;
189 	osi->os_dsl_dataset = ds;
190 	osi->os_spa = spa;
191 	osi->os_rootbp = bp;
192 	if (!BP_IS_HOLE(osi->os_rootbp)) {
193 		uint32_t aflags = ARC_WAIT;
194 		zbookmark_t zb;
195 		zb.zb_objset = ds ? ds->ds_object : 0;
196 		zb.zb_object = 0;
197 		zb.zb_level = -1;
198 		zb.zb_blkid = 0;
199 		if (DMU_OS_IS_L2CACHEABLE(osi))
200 			aflags |= ARC_L2CACHE;
201 
202 		dprintf_bp(osi->os_rootbp, "reading %s", "");
203 		/*
204 		 * NB: when bprewrite scrub can change the bp,
205 		 * and this is called from dmu_objset_open_ds_os, the bp
206 		 * could change, and we'll need a lock.
207 		 */
208 		err = arc_read_nolock(NULL, spa, osi->os_rootbp,
209 		    arc_getbuf_func, &osi->os_phys_buf,
210 		    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &aflags, &zb);
211 		if (err) {
212 			kmem_free(osi, sizeof (objset_impl_t));
213 			/* convert checksum errors into IO errors */
214 			if (err == ECKSUM)
215 				err = EIO;
216 			return (err);
217 		}
218 
219 		/* Increase the blocksize if we are permitted. */
220 		if (spa_version(spa) >= SPA_VERSION_USERSPACE &&
221 		    arc_buf_size(osi->os_phys_buf) < sizeof (objset_phys_t)) {
222 			arc_buf_t *buf = arc_buf_alloc(spa,
223 			    sizeof (objset_phys_t), &osi->os_phys_buf,
224 			    ARC_BUFC_METADATA);
225 			bzero(buf->b_data, sizeof (objset_phys_t));
226 			bcopy(osi->os_phys_buf->b_data, buf->b_data,
227 			    arc_buf_size(osi->os_phys_buf));
228 			(void) arc_buf_remove_ref(osi->os_phys_buf,
229 			    &osi->os_phys_buf);
230 			osi->os_phys_buf = buf;
231 		}
232 
233 		osi->os_phys = osi->os_phys_buf->b_data;
234 		osi->os_flags = osi->os_phys->os_flags;
235 	} else {
236 		int size = spa_version(spa) >= SPA_VERSION_USERSPACE ?
237 		    sizeof (objset_phys_t) : OBJSET_OLD_PHYS_SIZE;
238 		osi->os_phys_buf = arc_buf_alloc(spa, size,
239 		    &osi->os_phys_buf, ARC_BUFC_METADATA);
240 		osi->os_phys = osi->os_phys_buf->b_data;
241 		bzero(osi->os_phys, size);
242 	}
243 
244 	/*
245 	 * Note: the changed_cb will be called once before the register
246 	 * func returns, thus changing the checksum/compression from the
247 	 * default (fletcher2/off).  Snapshots don't need to know about
248 	 * checksum/compression/copies.
249 	 */
250 	if (ds) {
251 		err = dsl_prop_register(ds, "primarycache",
252 		    primary_cache_changed_cb, osi);
253 		if (err == 0)
254 			err = dsl_prop_register(ds, "secondarycache",
255 			    secondary_cache_changed_cb, osi);
256 		if (!dsl_dataset_is_snapshot(ds)) {
257 			if (err == 0)
258 				err = dsl_prop_register(ds, "checksum",
259 				    checksum_changed_cb, osi);
260 			if (err == 0)
261 				err = dsl_prop_register(ds, "compression",
262 				    compression_changed_cb, osi);
263 			if (err == 0)
264 				err = dsl_prop_register(ds, "copies",
265 				    copies_changed_cb, osi);
266 		}
267 		if (err) {
268 			VERIFY(arc_buf_remove_ref(osi->os_phys_buf,
269 			    &osi->os_phys_buf) == 1);
270 			kmem_free(osi, sizeof (objset_impl_t));
271 			return (err);
272 		}
273 	} else if (ds == NULL) {
274 		/* It's the meta-objset. */
275 		osi->os_checksum = ZIO_CHECKSUM_FLETCHER_4;
276 		osi->os_compress = ZIO_COMPRESS_LZJB;
277 		osi->os_copies = spa_max_replication(spa);
278 		osi->os_primary_cache = ZFS_CACHE_ALL;
279 		osi->os_secondary_cache = ZFS_CACHE_ALL;
280 	}
281 
282 	osi->os_zil_header = osi->os_phys->os_zil_header;
283 	osi->os_zil = zil_alloc(&osi->os, &osi->os_zil_header);
284 
285 	for (i = 0; i < TXG_SIZE; i++) {
286 		list_create(&osi->os_dirty_dnodes[i], sizeof (dnode_t),
287 		    offsetof(dnode_t, dn_dirty_link[i]));
288 		list_create(&osi->os_free_dnodes[i], sizeof (dnode_t),
289 		    offsetof(dnode_t, dn_dirty_link[i]));
290 	}
291 	list_create(&osi->os_dnodes, sizeof (dnode_t),
292 	    offsetof(dnode_t, dn_link));
293 	list_create(&osi->os_downgraded_dbufs, sizeof (dmu_buf_impl_t),
294 	    offsetof(dmu_buf_impl_t, db_link));
295 
296 	mutex_init(&osi->os_lock, NULL, MUTEX_DEFAULT, NULL);
297 	mutex_init(&osi->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
298 	mutex_init(&osi->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);
299 
300 	osi->os_meta_dnode = dnode_special_open(osi,
301 	    &osi->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT);
302 	if (arc_buf_size(osi->os_phys_buf) >= sizeof (objset_phys_t)) {
303 		osi->os_userused_dnode = dnode_special_open(osi,
304 		    &osi->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT);
305 		osi->os_groupused_dnode = dnode_special_open(osi,
306 		    &osi->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT);
307 	}
308 
309 	/*
310 	 * We should be the only thread trying to do this because we
311 	 * have ds_opening_lock
312 	 */
313 	if (ds) {
314 		VERIFY(NULL == dsl_dataset_set_user_ptr(ds, osi,
315 		    dmu_objset_evict));
316 	}
317 
318 	*osip = osi;
319 	return (0);
320 }
321 
322 static int
323 dmu_objset_open_ds_os(dsl_dataset_t *ds, objset_t *os, dmu_objset_type_t type)
324 {
325 	objset_impl_t *osi;
326 
327 	mutex_enter(&ds->ds_opening_lock);
328 	osi = dsl_dataset_get_user_ptr(ds);
329 	if (osi == NULL) {
330 		int err;
331 
332 		err = dmu_objset_open_impl(dsl_dataset_get_spa(ds),
333 		    ds, &ds->ds_phys->ds_bp, &osi);
334 		if (err) {
335 			mutex_exit(&ds->ds_opening_lock);
336 			return (err);
337 		}
338 	}
339 	mutex_exit(&ds->ds_opening_lock);
340 
341 	os->os = osi;
342 	os->os_mode = DS_MODE_NOHOLD;
343 
344 	if (type != DMU_OST_ANY && type != os->os->os_phys->os_type)
345 		return (EINVAL);
346 	return (0);
347 }
348 
349 int
350 dmu_objset_open_ds(dsl_dataset_t *ds, dmu_objset_type_t type, objset_t **osp)
351 {
352 	objset_t *os;
353 	int err;
354 
355 	os = kmem_alloc(sizeof (objset_t), KM_SLEEP);
356 	err = dmu_objset_open_ds_os(ds, os, type);
357 	if (err)
358 		kmem_free(os, sizeof (objset_t));
359 	else
360 		*osp = os;
361 	return (err);
362 }
363 
364 /* called from zpl */
365 int
366 dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
367     objset_t **osp)
368 {
369 	objset_t *os;
370 	dsl_dataset_t *ds;
371 	int err;
372 
373 	ASSERT(DS_MODE_TYPE(mode) == DS_MODE_USER ||
374 	    DS_MODE_TYPE(mode) == DS_MODE_OWNER);
375 
376 	os = kmem_alloc(sizeof (objset_t), KM_SLEEP);
377 	if (DS_MODE_TYPE(mode) == DS_MODE_USER)
378 		err = dsl_dataset_hold(name, os, &ds);
379 	else
380 		err = dsl_dataset_own(name, mode, os, &ds);
381 	if (err) {
382 		kmem_free(os, sizeof (objset_t));
383 		return (err);
384 	}
385 
386 	err = dmu_objset_open_ds_os(ds, os, type);
387 	if (err) {
388 		if (DS_MODE_TYPE(mode) == DS_MODE_USER)
389 			dsl_dataset_rele(ds, os);
390 		else
391 			dsl_dataset_disown(ds, os);
392 		kmem_free(os, sizeof (objset_t));
393 	} else {
394 		os->os_mode = mode;
395 		*osp = os;
396 	}
397 	return (err);
398 }
399 
400 void
401 dmu_objset_close(objset_t *os)
402 {
403 	ASSERT(DS_MODE_TYPE(os->os_mode) == DS_MODE_USER ||
404 	    DS_MODE_TYPE(os->os_mode) == DS_MODE_OWNER ||
405 	    DS_MODE_TYPE(os->os_mode) == DS_MODE_NOHOLD);
406 
407 	if (DS_MODE_TYPE(os->os_mode) == DS_MODE_USER)
408 		dsl_dataset_rele(os->os->os_dsl_dataset, os);
409 	else if (DS_MODE_TYPE(os->os_mode) == DS_MODE_OWNER)
410 		dsl_dataset_disown(os->os->os_dsl_dataset, os);
411 	kmem_free(os, sizeof (objset_t));
412 }
413 
414 int
415 dmu_objset_evict_dbufs(objset_t *os)
416 {
417 	objset_impl_t *osi = os->os;
418 	dnode_t *dn;
419 
420 	mutex_enter(&osi->os_lock);
421 
422 	/* process the mdn last, since the other dnodes have holds on it */
423 	list_remove(&osi->os_dnodes, osi->os_meta_dnode);
424 	list_insert_tail(&osi->os_dnodes, osi->os_meta_dnode);
425 
426 	/*
427 	 * Find the first dnode with holds.  We have to do this dance
428 	 * because dnode_add_ref() only works if you already have a
429 	 * hold.  If there are no holds then it has no dbufs so OK to
430 	 * skip.
431 	 */
432 	for (dn = list_head(&osi->os_dnodes);
433 	    dn && !dnode_add_ref(dn, FTAG);
434 	    dn = list_next(&osi->os_dnodes, dn))
435 		continue;
436 
437 	while (dn) {
438 		dnode_t *next_dn = dn;
439 
440 		do {
441 			next_dn = list_next(&osi->os_dnodes, next_dn);
442 		} while (next_dn && !dnode_add_ref(next_dn, FTAG));
443 
444 		mutex_exit(&osi->os_lock);
445 		dnode_evict_dbufs(dn);
446 		dnode_rele(dn, FTAG);
447 		mutex_enter(&osi->os_lock);
448 		dn = next_dn;
449 	}
450 	mutex_exit(&osi->os_lock);
451 	return (list_head(&osi->os_dnodes) != osi->os_meta_dnode);
452 }
453 
454 void
455 dmu_objset_evict(dsl_dataset_t *ds, void *arg)
456 {
457 	objset_impl_t *osi = arg;
458 	objset_t os;
459 	int i;
460 
461 	for (i = 0; i < TXG_SIZE; i++) {
462 		ASSERT(list_head(&osi->os_dirty_dnodes[i]) == NULL);
463 		ASSERT(list_head(&osi->os_free_dnodes[i]) == NULL);
464 	}
465 
466 	if (ds) {
467 		if (!dsl_dataset_is_snapshot(ds)) {
468 			VERIFY(0 == dsl_prop_unregister(ds, "checksum",
469 			    checksum_changed_cb, osi));
470 			VERIFY(0 == dsl_prop_unregister(ds, "compression",
471 			    compression_changed_cb, osi));
472 			VERIFY(0 == dsl_prop_unregister(ds, "copies",
473 			    copies_changed_cb, osi));
474 		}
475 		VERIFY(0 == dsl_prop_unregister(ds, "primarycache",
476 		    primary_cache_changed_cb, osi));
477 		VERIFY(0 == dsl_prop_unregister(ds, "secondarycache",
478 		    secondary_cache_changed_cb, osi));
479 	}
480 
481 	/*
482 	 * We should need only a single pass over the dnode list, since
483 	 * nothing can be added to the list at this point.
484 	 */
485 	os.os = osi;
486 	(void) dmu_objset_evict_dbufs(&os);
487 
488 	dnode_special_close(osi->os_meta_dnode);
489 	if (osi->os_userused_dnode) {
490 		dnode_special_close(osi->os_userused_dnode);
491 		dnode_special_close(osi->os_groupused_dnode);
492 	}
493 	zil_free(osi->os_zil);
494 
495 	ASSERT3P(list_head(&osi->os_dnodes), ==, NULL);
496 
497 	VERIFY(arc_buf_remove_ref(osi->os_phys_buf, &osi->os_phys_buf) == 1);
498 	mutex_destroy(&osi->os_lock);
499 	mutex_destroy(&osi->os_obj_lock);
500 	mutex_destroy(&osi->os_user_ptr_lock);
501 	kmem_free(osi, sizeof (objset_impl_t));
502 }
503 
504 /* called from dsl for meta-objset */
505 objset_impl_t *
506 dmu_objset_create_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
507     dmu_objset_type_t type, dmu_tx_t *tx)
508 {
509 	objset_impl_t *osi;
510 	dnode_t *mdn;
511 
512 	ASSERT(dmu_tx_is_syncing(tx));
513 	if (ds)
514 		mutex_enter(&ds->ds_opening_lock);
515 	VERIFY(0 == dmu_objset_open_impl(spa, ds, bp, &osi));
516 	if (ds)
517 		mutex_exit(&ds->ds_opening_lock);
518 	mdn = osi->os_meta_dnode;
519 
520 	dnode_allocate(mdn, DMU_OT_DNODE, 1 << DNODE_BLOCK_SHIFT,
521 	    DN_MAX_INDBLKSHIFT, DMU_OT_NONE, 0, tx);
522 
523 	/*
524 	 * We don't want to have to increase the meta-dnode's nlevels
525 	 * later, because then we could do it in quescing context while
526 	 * we are also accessing it in open context.
527 	 *
528 	 * This precaution is not necessary for the MOS (ds == NULL),
529 	 * because the MOS is only updated in syncing context.
530 	 * This is most fortunate: the MOS is the only objset that
531 	 * needs to be synced multiple times as spa_sync() iterates
532 	 * to convergence, so minimizing its dn_nlevels matters.
533 	 */
534 	if (ds != NULL) {
535 		int levels = 1;
536 
537 		/*
538 		 * Determine the number of levels necessary for the meta-dnode
539 		 * to contain DN_MAX_OBJECT dnodes.
540 		 */
541 		while ((uint64_t)mdn->dn_nblkptr << (mdn->dn_datablkshift +
542 		    (levels - 1) * (mdn->dn_indblkshift - SPA_BLKPTRSHIFT)) <
543 		    DN_MAX_OBJECT * sizeof (dnode_phys_t))
544 			levels++;
545 
546 		mdn->dn_next_nlevels[tx->tx_txg & TXG_MASK] =
547 		    mdn->dn_nlevels = levels;
548 	}
549 
550 	ASSERT(type != DMU_OST_NONE);
551 	ASSERT(type != DMU_OST_ANY);
552 	ASSERT(type < DMU_OST_NUMTYPES);
553 	osi->os_phys->os_type = type;
554 	if (dmu_objset_userused_enabled(osi)) {
555 		osi->os_phys->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
556 		osi->os_flags = osi->os_phys->os_flags;
557 	}
558 
559 	dsl_dataset_dirty(ds, tx);
560 
561 	return (osi);
562 }
563 
564 struct oscarg {
565 	void (*userfunc)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
566 	void *userarg;
567 	dsl_dataset_t *clone_parent;
568 	const char *lastname;
569 	dmu_objset_type_t type;
570 	uint64_t flags;
571 };
572 
573 /*ARGSUSED*/
574 static int
575 dmu_objset_create_check(void *arg1, void *arg2, dmu_tx_t *tx)
576 {
577 	dsl_dir_t *dd = arg1;
578 	struct oscarg *oa = arg2;
579 	objset_t *mos = dd->dd_pool->dp_meta_objset;
580 	int err;
581 	uint64_t ddobj;
582 
583 	err = zap_lookup(mos, dd->dd_phys->dd_child_dir_zapobj,
584 	    oa->lastname, sizeof (uint64_t), 1, &ddobj);
585 	if (err != ENOENT)
586 		return (err ? err : EEXIST);
587 
588 	if (oa->clone_parent != NULL) {
589 		/*
590 		 * You can't clone across pools.
591 		 */
592 		if (oa->clone_parent->ds_dir->dd_pool != dd->dd_pool)
593 			return (EXDEV);
594 
595 		/*
596 		 * You can only clone snapshots, not the head datasets.
597 		 */
598 		if (oa->clone_parent->ds_phys->ds_num_children == 0)
599 			return (EINVAL);
600 	}
601 
602 	return (0);
603 }
604 
605 static void
606 dmu_objset_create_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
607 {
608 	dsl_dir_t *dd = arg1;
609 	struct oscarg *oa = arg2;
610 	dsl_dataset_t *ds;
611 	blkptr_t *bp;
612 	uint64_t dsobj;
613 
614 	ASSERT(dmu_tx_is_syncing(tx));
615 
616 	dsobj = dsl_dataset_create_sync(dd, oa->lastname,
617 	    oa->clone_parent, oa->flags, cr, tx);
618 
619 	VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool, dsobj, FTAG, &ds));
620 	bp = dsl_dataset_get_blkptr(ds);
621 	if (BP_IS_HOLE(bp)) {
622 		objset_impl_t *osi;
623 
624 		/* This is an empty dmu_objset; not a clone. */
625 		osi = dmu_objset_create_impl(dsl_dataset_get_spa(ds),
626 		    ds, bp, oa->type, tx);
627 
628 		if (oa->userfunc)
629 			oa->userfunc(&osi->os, oa->userarg, cr, tx);
630 	}
631 
632 	spa_history_internal_log(LOG_DS_CREATE, dd->dd_pool->dp_spa,
633 	    tx, cr, "dataset = %llu", dsobj);
634 
635 	dsl_dataset_rele(ds, FTAG);
636 }
637 
638 int
639 dmu_objset_create(const char *name, dmu_objset_type_t type,
640     objset_t *clone_parent, uint64_t flags,
641     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg)
642 {
643 	dsl_dir_t *pdd;
644 	const char *tail;
645 	int err = 0;
646 	struct oscarg oa = { 0 };
647 
648 	ASSERT(strchr(name, '@') == NULL);
649 	err = dsl_dir_open(name, FTAG, &pdd, &tail);
650 	if (err)
651 		return (err);
652 	if (tail == NULL) {
653 		dsl_dir_close(pdd, FTAG);
654 		return (EEXIST);
655 	}
656 
657 	dprintf("name=%s\n", name);
658 
659 	oa.userfunc = func;
660 	oa.userarg = arg;
661 	oa.lastname = tail;
662 	oa.type = type;
663 	oa.flags = flags;
664 
665 	if (clone_parent != NULL) {
666 		/*
667 		 * You can't clone to a different type.
668 		 */
669 		if (clone_parent->os->os_phys->os_type != type) {
670 			dsl_dir_close(pdd, FTAG);
671 			return (EINVAL);
672 		}
673 		oa.clone_parent = clone_parent->os->os_dsl_dataset;
674 	}
675 	err = dsl_sync_task_do(pdd->dd_pool, dmu_objset_create_check,
676 	    dmu_objset_create_sync, pdd, &oa, 5);
677 	dsl_dir_close(pdd, FTAG);
678 	return (err);
679 }
680 
681 int
682 dmu_objset_destroy(const char *name)
683 {
684 	objset_t *os;
685 	int error;
686 
687 	/*
688 	 * If it looks like we'll be able to destroy it, and there's
689 	 * an unplayed replay log sitting around, destroy the log.
690 	 * It would be nicer to do this in dsl_dataset_destroy_sync(),
691 	 * but the replay log objset is modified in open context.
692 	 */
693 	error = dmu_objset_open(name, DMU_OST_ANY,
694 	    DS_MODE_OWNER|DS_MODE_READONLY|DS_MODE_INCONSISTENT, &os);
695 	if (error == 0) {
696 		dsl_dataset_t *ds = os->os->os_dsl_dataset;
697 		zil_destroy(dmu_objset_zil(os), B_FALSE);
698 
699 		error = dsl_dataset_destroy(ds, os);
700 		/*
701 		 * dsl_dataset_destroy() closes the ds.
702 		 */
703 		kmem_free(os, sizeof (objset_t));
704 	}
705 
706 	return (error);
707 }
708 
709 /*
710  * This will close the objset.
711  */
712 int
713 dmu_objset_rollback(objset_t *os)
714 {
715 	int err;
716 	dsl_dataset_t *ds;
717 
718 	ds = os->os->os_dsl_dataset;
719 
720 	if (!dsl_dataset_tryown(ds, TRUE, os)) {
721 		dmu_objset_close(os);
722 		return (EBUSY);
723 	}
724 
725 	err = dsl_dataset_rollback(ds, os->os->os_phys->os_type);
726 
727 	/*
728 	 * NB: we close the objset manually because the rollback
729 	 * actually implicitly called dmu_objset_evict(), thus freeing
730 	 * the objset_impl_t.
731 	 */
732 	dsl_dataset_disown(ds, os);
733 	kmem_free(os, sizeof (objset_t));
734 	return (err);
735 }
736 
737 struct snaparg {
738 	dsl_sync_task_group_t *dstg;
739 	char *snapname;
740 	char failed[MAXPATHLEN];
741 	boolean_t checkperms;
742 	nvlist_t *props;
743 };
744 
745 static int
746 snapshot_check(void *arg1, void *arg2, dmu_tx_t *tx)
747 {
748 	objset_t *os = arg1;
749 	struct snaparg *sn = arg2;
750 
751 	/* The props have already been checked by zfs_check_userprops(). */
752 
753 	return (dsl_dataset_snapshot_check(os->os->os_dsl_dataset,
754 	    sn->snapname, tx));
755 }
756 
757 static void
758 snapshot_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
759 {
760 	objset_t *os = arg1;
761 	dsl_dataset_t *ds = os->os->os_dsl_dataset;
762 	struct snaparg *sn = arg2;
763 
764 	dsl_dataset_snapshot_sync(ds, sn->snapname, cr, tx);
765 
766 	if (sn->props)
767 		dsl_props_set_sync(ds->ds_prev, sn->props, cr, tx);
768 }
769 
770 static int
771 dmu_objset_snapshot_one(char *name, void *arg)
772 {
773 	struct snaparg *sn = arg;
774 	objset_t *os;
775 	int err;
776 
777 	(void) strcpy(sn->failed, name);
778 
779 	/*
780 	 * Check permissions only when requested.  This only applies when
781 	 * doing a recursive snapshot.  The permission checks for the starting
782 	 * dataset have already been performed in zfs_secpolicy_snapshot()
783 	 */
784 	if (sn->checkperms == B_TRUE &&
785 	    (err = zfs_secpolicy_snapshot_perms(name, CRED())))
786 		return (err);
787 
788 	err = dmu_objset_open(name, DMU_OST_ANY, DS_MODE_USER, &os);
789 	if (err != 0)
790 		return (err);
791 
792 	/* If the objset is in an inconsistent state, return busy */
793 	if (os->os->os_dsl_dataset->ds_phys->ds_flags & DS_FLAG_INCONSISTENT) {
794 		dmu_objset_close(os);
795 		return (EBUSY);
796 	}
797 
798 	/*
799 	 * NB: we need to wait for all in-flight changes to get to disk,
800 	 * so that we snapshot those changes.  zil_suspend does this as
801 	 * a side effect.
802 	 */
803 	err = zil_suspend(dmu_objset_zil(os));
804 	if (err == 0) {
805 		dsl_sync_task_create(sn->dstg, snapshot_check,
806 		    snapshot_sync, os, sn, 3);
807 	} else {
808 		dmu_objset_close(os);
809 	}
810 
811 	return (err);
812 }
813 
814 int
815 dmu_objset_snapshot(char *fsname, char *snapname,
816     nvlist_t *props, boolean_t recursive)
817 {
818 	dsl_sync_task_t *dst;
819 	struct snaparg sn;
820 	spa_t *spa;
821 	int err;
822 
823 	(void) strcpy(sn.failed, fsname);
824 
825 	err = spa_open(fsname, &spa, FTAG);
826 	if (err)
827 		return (err);
828 
829 	sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
830 	sn.snapname = snapname;
831 	sn.props = props;
832 
833 	if (recursive) {
834 		sn.checkperms = B_TRUE;
835 		err = dmu_objset_find(fsname,
836 		    dmu_objset_snapshot_one, &sn, DS_FIND_CHILDREN);
837 	} else {
838 		sn.checkperms = B_FALSE;
839 		err = dmu_objset_snapshot_one(fsname, &sn);
840 	}
841 
842 	if (err == 0)
843 		err = dsl_sync_task_group_wait(sn.dstg);
844 
845 	for (dst = list_head(&sn.dstg->dstg_tasks); dst;
846 	    dst = list_next(&sn.dstg->dstg_tasks, dst)) {
847 		objset_t *os = dst->dst_arg1;
848 		dsl_dataset_t *ds = os->os->os_dsl_dataset;
849 		if (dst->dst_err)
850 			dsl_dataset_name(ds, sn.failed);
851 		zil_resume(dmu_objset_zil(os));
852 		dmu_objset_close(os);
853 	}
854 
855 	if (err)
856 		(void) strcpy(fsname, sn.failed);
857 	dsl_sync_task_group_destroy(sn.dstg);
858 	spa_close(spa, FTAG);
859 	return (err);
860 }
861 
862 static void
863 dmu_objset_sync_dnodes(list_t *list, list_t *newlist, dmu_tx_t *tx)
864 {
865 	dnode_t *dn;
866 
867 	while (dn = list_head(list)) {
868 		ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
869 		ASSERT(dn->dn_dbuf->db_data_pending);
870 		/*
871 		 * Initialize dn_zio outside dnode_sync() because the
872 		 * meta-dnode needs to set it ouside dnode_sync().
873 		 */
874 		dn->dn_zio = dn->dn_dbuf->db_data_pending->dr_zio;
875 		ASSERT(dn->dn_zio);
876 
877 		ASSERT3U(dn->dn_nlevels, <=, DN_MAX_LEVELS);
878 		list_remove(list, dn);
879 
880 		if (newlist) {
881 			(void) dnode_add_ref(dn, newlist);
882 			list_insert_tail(newlist, dn);
883 		}
884 
885 		dnode_sync(dn, tx);
886 	}
887 }
888 
889 /* ARGSUSED */
890 static void
891 ready(zio_t *zio, arc_buf_t *abuf, void *arg)
892 {
893 	blkptr_t *bp = zio->io_bp;
894 	blkptr_t *bp_orig = &zio->io_bp_orig;
895 	objset_impl_t *os = arg;
896 	dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;
897 
898 	ASSERT(bp == os->os_rootbp);
899 	ASSERT(BP_GET_TYPE(bp) == DMU_OT_OBJSET);
900 	ASSERT(BP_GET_LEVEL(bp) == 0);
901 
902 	/*
903 	 * Update rootbp fill count: it should be the number of objects
904 	 * allocated in the object set (not counting the "special"
905 	 * objects that are stored in the objset_phys_t -- the meta
906 	 * dnode and user/group accounting objects).
907 	 */
908 	bp->blk_fill = 0;
909 	for (int i = 0; i < dnp->dn_nblkptr; i++)
910 		bp->blk_fill += dnp->dn_blkptr[i].blk_fill;
911 
912 	if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
913 		ASSERT(DVA_EQUAL(BP_IDENTITY(bp), BP_IDENTITY(bp_orig)));
914 	} else {
915 		if (zio->io_bp_orig.blk_birth == os->os_synctx->tx_txg)
916 			(void) dsl_dataset_block_kill(os->os_dsl_dataset,
917 			    &zio->io_bp_orig, zio, os->os_synctx);
918 		dsl_dataset_block_born(os->os_dsl_dataset, bp, os->os_synctx);
919 	}
920 }
921 
922 /* called from dsl */
923 void
924 dmu_objset_sync(objset_impl_t *os, zio_t *pio, dmu_tx_t *tx)
925 {
926 	int txgoff;
927 	zbookmark_t zb;
928 	writeprops_t wp = { 0 };
929 	zio_t *zio;
930 	list_t *list;
931 	list_t *newlist = NULL;
932 	dbuf_dirty_record_t *dr;
933 
934 	dprintf_ds(os->os_dsl_dataset, "txg=%llu\n", tx->tx_txg);
935 
936 	ASSERT(dmu_tx_is_syncing(tx));
937 	/* XXX the write_done callback should really give us the tx... */
938 	os->os_synctx = tx;
939 
940 	if (os->os_dsl_dataset == NULL) {
941 		/*
942 		 * This is the MOS.  If we have upgraded,
943 		 * spa_max_replication() could change, so reset
944 		 * os_copies here.
945 		 */
946 		os->os_copies = spa_max_replication(os->os_spa);
947 	}
948 
949 	/*
950 	 * Create the root block IO
951 	 */
952 	zb.zb_objset = os->os_dsl_dataset ? os->os_dsl_dataset->ds_object : 0;
953 	zb.zb_object = 0;
954 	zb.zb_level = -1;	/* for block ordering; it's level 0 on disk */
955 	zb.zb_blkid = 0;
956 
957 	wp.wp_type = DMU_OT_OBJSET;
958 	wp.wp_level = 0;	/* on-disk BP level; see above */
959 	wp.wp_copies = os->os_copies;
960 	wp.wp_oschecksum = os->os_checksum;
961 	wp.wp_oscompress = os->os_compress;
962 
963 	if (BP_IS_OLDER(os->os_rootbp, tx->tx_txg)) {
964 		(void) dsl_dataset_block_kill(os->os_dsl_dataset,
965 		    os->os_rootbp, pio, tx);
966 	}
967 
968 	arc_release(os->os_phys_buf, &os->os_phys_buf);
969 
970 	zio = arc_write(pio, os->os_spa, &wp, DMU_OS_IS_L2CACHEABLE(os),
971 	    tx->tx_txg, os->os_rootbp, os->os_phys_buf, ready, NULL, os,
972 	    ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
973 
974 	/*
975 	 * Sync special dnodes - the parent IO for the sync is the root block
976 	 */
977 	os->os_meta_dnode->dn_zio = zio;
978 	dnode_sync(os->os_meta_dnode, tx);
979 
980 	os->os_phys->os_flags = os->os_flags;
981 
982 	if (os->os_userused_dnode &&
983 	    os->os_userused_dnode->dn_type != DMU_OT_NONE) {
984 		os->os_userused_dnode->dn_zio = zio;
985 		dnode_sync(os->os_userused_dnode, tx);
986 		os->os_groupused_dnode->dn_zio = zio;
987 		dnode_sync(os->os_groupused_dnode, tx);
988 	}
989 
990 	txgoff = tx->tx_txg & TXG_MASK;
991 
992 	if (dmu_objset_userused_enabled(os)) {
993 		newlist = &os->os_synced_dnodes;
994 		/*
995 		 * We must create the list here because it uses the
996 		 * dn_dirty_link[] of this txg.
997 		 */
998 		list_create(newlist, sizeof (dnode_t),
999 		    offsetof(dnode_t, dn_dirty_link[txgoff]));
1000 	}
1001 
1002 	dmu_objset_sync_dnodes(&os->os_free_dnodes[txgoff], newlist, tx);
1003 	dmu_objset_sync_dnodes(&os->os_dirty_dnodes[txgoff], newlist, tx);
1004 
1005 	list = &os->os_meta_dnode->dn_dirty_records[txgoff];
1006 	while (dr = list_head(list)) {
1007 		ASSERT(dr->dr_dbuf->db_level == 0);
1008 		list_remove(list, dr);
1009 		if (dr->dr_zio)
1010 			zio_nowait(dr->dr_zio);
1011 	}
1012 	/*
1013 	 * Free intent log blocks up to this tx.
1014 	 */
1015 	zil_sync(os->os_zil, tx);
1016 	os->os_phys->os_zil_header = os->os_zil_header;
1017 	zio_nowait(zio);
1018 }
1019 
1020 static objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
1021 
1022 void
1023 dmu_objset_register_type(dmu_objset_type_t ost, objset_used_cb_t *cb)
1024 {
1025 	used_cbs[ost] = cb;
1026 }
1027 
1028 boolean_t
1029 dmu_objset_userused_enabled(objset_impl_t *os)
1030 {
1031 	return (spa_version(os->os_spa) >= SPA_VERSION_USERSPACE &&
1032 	    used_cbs[os->os_phys->os_type] &&
1033 	    os->os_userused_dnode);
1034 }
1035 
1036 void
1037 dmu_objset_do_userquota_callbacks(objset_impl_t *os, dmu_tx_t *tx)
1038 {
1039 	dnode_t *dn;
1040 	list_t *list = &os->os_synced_dnodes;
1041 	static const char zerobuf[DN_MAX_BONUSLEN] = {0};
1042 
1043 	ASSERT(list_head(list) == NULL || dmu_objset_userused_enabled(os));
1044 
1045 	while (dn = list_head(list)) {
1046 		dmu_object_type_t bonustype;
1047 
1048 		ASSERT(!DMU_OBJECT_IS_SPECIAL(dn->dn_object));
1049 		ASSERT(dn->dn_oldphys);
1050 		ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE ||
1051 		    dn->dn_phys->dn_flags &
1052 		    DNODE_FLAG_USERUSED_ACCOUNTED);
1053 
1054 		/* Allocate the user/groupused objects if necessary. */
1055 		if (os->os_userused_dnode->dn_type == DMU_OT_NONE) {
1056 			VERIFY(0 == zap_create_claim(&os->os,
1057 			    DMU_USERUSED_OBJECT,
1058 			    DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
1059 			VERIFY(0 == zap_create_claim(&os->os,
1060 			    DMU_GROUPUSED_OBJECT,
1061 			    DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
1062 		}
1063 
1064 		/*
1065 		 * If the object was not previously
1066 		 * accounted, pretend that it was free.
1067 		 */
1068 		if (!(dn->dn_oldphys->dn_flags &
1069 		    DNODE_FLAG_USERUSED_ACCOUNTED)) {
1070 			bzero(dn->dn_oldphys, sizeof (dnode_phys_t));
1071 		}
1072 
1073 		/*
1074 		 * If the object was freed, use the previous bonustype.
1075 		 */
1076 		bonustype = dn->dn_phys->dn_bonustype ?
1077 		    dn->dn_phys->dn_bonustype : dn->dn_oldphys->dn_bonustype;
1078 		ASSERT(dn->dn_phys->dn_type != 0 ||
1079 		    (bcmp(DN_BONUS(dn->dn_phys), zerobuf,
1080 		    DN_MAX_BONUSLEN) == 0 &&
1081 		    DN_USED_BYTES(dn->dn_phys) == 0));
1082 		ASSERT(dn->dn_oldphys->dn_type != 0 ||
1083 		    (bcmp(DN_BONUS(dn->dn_oldphys), zerobuf,
1084 		    DN_MAX_BONUSLEN) == 0 &&
1085 		    DN_USED_BYTES(dn->dn_oldphys) == 0));
1086 		used_cbs[os->os_phys->os_type](&os->os, bonustype,
1087 		    DN_BONUS(dn->dn_oldphys), DN_BONUS(dn->dn_phys),
1088 		    DN_USED_BYTES(dn->dn_oldphys),
1089 		    DN_USED_BYTES(dn->dn_phys), tx);
1090 
1091 		/*
1092 		 * The mutex is needed here for interlock with dnode_allocate.
1093 		 */
1094 		mutex_enter(&dn->dn_mtx);
1095 		zio_buf_free(dn->dn_oldphys, sizeof (dnode_phys_t));
1096 		dn->dn_oldphys = NULL;
1097 		mutex_exit(&dn->dn_mtx);
1098 
1099 		list_remove(list, dn);
1100 		dnode_rele(dn, list);
1101 	}
1102 }
1103 
1104 boolean_t
1105 dmu_objset_userspace_present(objset_t *os)
1106 {
1107 	return (os->os->os_phys->os_flags &
1108 	    OBJSET_FLAG_USERACCOUNTING_COMPLETE);
1109 }
1110 
1111 int
1112 dmu_objset_userspace_upgrade(objset_t *os)
1113 {
1114 	uint64_t obj;
1115 	int err = 0;
1116 
1117 	if (dmu_objset_userspace_present(os))
1118 		return (0);
1119 	if (!dmu_objset_userused_enabled(os->os))
1120 		return (ENOTSUP);
1121 	if (dmu_objset_is_snapshot(os))
1122 		return (EINVAL);
1123 
1124 	/*
1125 	 * We simply need to mark every object dirty, so that it will be
1126 	 * synced out and now accounted.  If this is called
1127 	 * concurrently, or if we already did some work before crashing,
1128 	 * that's fine, since we track each object's accounted state
1129 	 * independently.
1130 	 */
1131 
1132 	for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE, 0)) {
1133 		dmu_tx_t *tx;
1134 		dmu_buf_t *db;
1135 		int objerr;
1136 
1137 		if (issig(JUSTLOOKING) && issig(FORREAL))
1138 			return (EINTR);
1139 
1140 		objerr = dmu_bonus_hold(os, obj, FTAG, &db);
1141 		if (objerr)
1142 			continue;
1143 		tx = dmu_tx_create(os);
1144 		dmu_tx_hold_bonus(tx, obj);
1145 		objerr = dmu_tx_assign(tx, TXG_WAIT);
1146 		if (objerr) {
1147 			dmu_tx_abort(tx);
1148 			continue;
1149 		}
1150 		dmu_buf_will_dirty(db, tx);
1151 		dmu_buf_rele(db, FTAG);
1152 		dmu_tx_commit(tx);
1153 	}
1154 
1155 	os->os->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
1156 	txg_wait_synced(dmu_objset_pool(os), 0);
1157 	return (0);
1158 }
1159 
1160 void
1161 dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
1162     uint64_t *usedobjsp, uint64_t *availobjsp)
1163 {
1164 	dsl_dataset_space(os->os->os_dsl_dataset, refdbytesp, availbytesp,
1165 	    usedobjsp, availobjsp);
1166 }
1167 
1168 uint64_t
1169 dmu_objset_fsid_guid(objset_t *os)
1170 {
1171 	return (dsl_dataset_fsid_guid(os->os->os_dsl_dataset));
1172 }
1173 
1174 void
1175 dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat)
1176 {
1177 	stat->dds_type = os->os->os_phys->os_type;
1178 	if (os->os->os_dsl_dataset)
1179 		dsl_dataset_fast_stat(os->os->os_dsl_dataset, stat);
1180 }
1181 
1182 void
1183 dmu_objset_stats(objset_t *os, nvlist_t *nv)
1184 {
1185 	ASSERT(os->os->os_dsl_dataset ||
1186 	    os->os->os_phys->os_type == DMU_OST_META);
1187 
1188 	if (os->os->os_dsl_dataset != NULL)
1189 		dsl_dataset_stats(os->os->os_dsl_dataset, nv);
1190 
1191 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_TYPE,
1192 	    os->os->os_phys->os_type);
1193 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERACCOUNTING,
1194 	    dmu_objset_userspace_present(os));
1195 }
1196 
1197 int
1198 dmu_objset_is_snapshot(objset_t *os)
1199 {
1200 	if (os->os->os_dsl_dataset != NULL)
1201 		return (dsl_dataset_is_snapshot(os->os->os_dsl_dataset));
1202 	else
1203 		return (B_FALSE);
1204 }
1205 
1206 int
1207 dmu_snapshot_realname(objset_t *os, char *name, char *real, int maxlen,
1208     boolean_t *conflict)
1209 {
1210 	dsl_dataset_t *ds = os->os->os_dsl_dataset;
1211 	uint64_t ignored;
1212 
1213 	if (ds->ds_phys->ds_snapnames_zapobj == 0)
1214 		return (ENOENT);
1215 
1216 	return (zap_lookup_norm(ds->ds_dir->dd_pool->dp_meta_objset,
1217 	    ds->ds_phys->ds_snapnames_zapobj, name, 8, 1, &ignored, MT_FIRST,
1218 	    real, maxlen, conflict));
1219 }
1220 
1221 int
1222 dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
1223     uint64_t *idp, uint64_t *offp, boolean_t *case_conflict)
1224 {
1225 	dsl_dataset_t *ds = os->os->os_dsl_dataset;
1226 	zap_cursor_t cursor;
1227 	zap_attribute_t attr;
1228 
1229 	if (ds->ds_phys->ds_snapnames_zapobj == 0)
1230 		return (ENOENT);
1231 
1232 	zap_cursor_init_serialized(&cursor,
1233 	    ds->ds_dir->dd_pool->dp_meta_objset,
1234 	    ds->ds_phys->ds_snapnames_zapobj, *offp);
1235 
1236 	if (zap_cursor_retrieve(&cursor, &attr) != 0) {
1237 		zap_cursor_fini(&cursor);
1238 		return (ENOENT);
1239 	}
1240 
1241 	if (strlen(attr.za_name) + 1 > namelen) {
1242 		zap_cursor_fini(&cursor);
1243 		return (ENAMETOOLONG);
1244 	}
1245 
1246 	(void) strcpy(name, attr.za_name);
1247 	if (idp)
1248 		*idp = attr.za_first_integer;
1249 	if (case_conflict)
1250 		*case_conflict = attr.za_normalization_conflict;
1251 	zap_cursor_advance(&cursor);
1252 	*offp = zap_cursor_serialize(&cursor);
1253 	zap_cursor_fini(&cursor);
1254 
1255 	return (0);
1256 }
1257 
1258 int
1259 dmu_dir_list_next(objset_t *os, int namelen, char *name,
1260     uint64_t *idp, uint64_t *offp)
1261 {
1262 	dsl_dir_t *dd = os->os->os_dsl_dataset->ds_dir;
1263 	zap_cursor_t cursor;
1264 	zap_attribute_t attr;
1265 
1266 	/* there is no next dir on a snapshot! */
1267 	if (os->os->os_dsl_dataset->ds_object !=
1268 	    dd->dd_phys->dd_head_dataset_obj)
1269 		return (ENOENT);
1270 
1271 	zap_cursor_init_serialized(&cursor,
1272 	    dd->dd_pool->dp_meta_objset,
1273 	    dd->dd_phys->dd_child_dir_zapobj, *offp);
1274 
1275 	if (zap_cursor_retrieve(&cursor, &attr) != 0) {
1276 		zap_cursor_fini(&cursor);
1277 		return (ENOENT);
1278 	}
1279 
1280 	if (strlen(attr.za_name) + 1 > namelen) {
1281 		zap_cursor_fini(&cursor);
1282 		return (ENAMETOOLONG);
1283 	}
1284 
1285 	(void) strcpy(name, attr.za_name);
1286 	if (idp)
1287 		*idp = attr.za_first_integer;
1288 	zap_cursor_advance(&cursor);
1289 	*offp = zap_cursor_serialize(&cursor);
1290 	zap_cursor_fini(&cursor);
1291 
1292 	return (0);
1293 }
1294 
1295 struct findarg {
1296 	int (*func)(char *, void *);
1297 	void *arg;
1298 };
1299 
1300 /* ARGSUSED */
1301 static int
1302 findfunc(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
1303 {
1304 	struct findarg *fa = arg;
1305 	return (fa->func((char *)dsname, fa->arg));
1306 }
1307 
1308 /*
1309  * Find all objsets under name, and for each, call 'func(child_name, arg)'.
1310  * Perhaps change all callers to use dmu_objset_find_spa()?
1311  */
1312 int
1313 dmu_objset_find(char *name, int func(char *, void *), void *arg, int flags)
1314 {
1315 	struct findarg fa;
1316 	fa.func = func;
1317 	fa.arg = arg;
1318 	return (dmu_objset_find_spa(NULL, name, findfunc, &fa, flags));
1319 }
1320 
1321 /*
1322  * Find all objsets under name, call func on each
1323  */
1324 int
1325 dmu_objset_find_spa(spa_t *spa, const char *name,
1326     int func(spa_t *, uint64_t, const char *, void *), void *arg, int flags)
1327 {
1328 	dsl_dir_t *dd;
1329 	dsl_pool_t *dp;
1330 	dsl_dataset_t *ds;
1331 	zap_cursor_t zc;
1332 	zap_attribute_t *attr;
1333 	char *child;
1334 	uint64_t thisobj;
1335 	int err;
1336 
1337 	if (name == NULL)
1338 		name = spa_name(spa);
1339 	err = dsl_dir_open_spa(spa, name, FTAG, &dd, NULL);
1340 	if (err)
1341 		return (err);
1342 
1343 	/* Don't visit hidden ($MOS & $ORIGIN) objsets. */
1344 	if (dd->dd_myname[0] == '$') {
1345 		dsl_dir_close(dd, FTAG);
1346 		return (0);
1347 	}
1348 
1349 	thisobj = dd->dd_phys->dd_head_dataset_obj;
1350 	attr = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
1351 	dp = dd->dd_pool;
1352 
1353 	/*
1354 	 * Iterate over all children.
1355 	 */
1356 	if (flags & DS_FIND_CHILDREN) {
1357 		for (zap_cursor_init(&zc, dp->dp_meta_objset,
1358 		    dd->dd_phys->dd_child_dir_zapobj);
1359 		    zap_cursor_retrieve(&zc, attr) == 0;
1360 		    (void) zap_cursor_advance(&zc)) {
1361 			ASSERT(attr->za_integer_length == sizeof (uint64_t));
1362 			ASSERT(attr->za_num_integers == 1);
1363 
1364 			child = kmem_alloc(MAXPATHLEN, KM_SLEEP);
1365 			(void) strcpy(child, name);
1366 			(void) strcat(child, "/");
1367 			(void) strcat(child, attr->za_name);
1368 			err = dmu_objset_find_spa(spa, child, func, arg, flags);
1369 			kmem_free(child, MAXPATHLEN);
1370 			if (err)
1371 				break;
1372 		}
1373 		zap_cursor_fini(&zc);
1374 
1375 		if (err) {
1376 			dsl_dir_close(dd, FTAG);
1377 			kmem_free(attr, sizeof (zap_attribute_t));
1378 			return (err);
1379 		}
1380 	}
1381 
1382 	/*
1383 	 * Iterate over all snapshots.
1384 	 */
1385 	if (flags & DS_FIND_SNAPSHOTS) {
1386 		if (!dsl_pool_sync_context(dp))
1387 			rw_enter(&dp->dp_config_rwlock, RW_READER);
1388 		err = dsl_dataset_hold_obj(dp, thisobj, FTAG, &ds);
1389 		if (!dsl_pool_sync_context(dp))
1390 			rw_exit(&dp->dp_config_rwlock);
1391 
1392 		if (err == 0) {
1393 			uint64_t snapobj = ds->ds_phys->ds_snapnames_zapobj;
1394 			dsl_dataset_rele(ds, FTAG);
1395 
1396 			for (zap_cursor_init(&zc, dp->dp_meta_objset, snapobj);
1397 			    zap_cursor_retrieve(&zc, attr) == 0;
1398 			    (void) zap_cursor_advance(&zc)) {
1399 				ASSERT(attr->za_integer_length ==
1400 				    sizeof (uint64_t));
1401 				ASSERT(attr->za_num_integers == 1);
1402 
1403 				child = kmem_alloc(MAXPATHLEN, KM_SLEEP);
1404 				(void) strcpy(child, name);
1405 				(void) strcat(child, "@");
1406 				(void) strcat(child, attr->za_name);
1407 				err = func(spa, attr->za_first_integer,
1408 				    child, arg);
1409 				kmem_free(child, MAXPATHLEN);
1410 				if (err)
1411 					break;
1412 			}
1413 			zap_cursor_fini(&zc);
1414 		}
1415 	}
1416 
1417 	dsl_dir_close(dd, FTAG);
1418 	kmem_free(attr, sizeof (zap_attribute_t));
1419 
1420 	if (err)
1421 		return (err);
1422 
1423 	/*
1424 	 * Apply to self if appropriate.
1425 	 */
1426 	err = func(spa, thisobj, name, arg);
1427 	return (err);
1428 }
1429 
1430 /* ARGSUSED */
1431 int
1432 dmu_objset_prefetch(char *name, void *arg)
1433 {
1434 	dsl_dataset_t *ds;
1435 
1436 	if (dsl_dataset_hold(name, FTAG, &ds))
1437 		return (0);
1438 
1439 	if (!BP_IS_HOLE(&ds->ds_phys->ds_bp)) {
1440 		mutex_enter(&ds->ds_opening_lock);
1441 		if (!dsl_dataset_get_user_ptr(ds)) {
1442 			uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
1443 			zbookmark_t zb;
1444 
1445 			zb.zb_objset = ds->ds_object;
1446 			zb.zb_object = 0;
1447 			zb.zb_level = -1;
1448 			zb.zb_blkid = 0;
1449 
1450 			(void) arc_read_nolock(NULL, dsl_dataset_get_spa(ds),
1451 			    &ds->ds_phys->ds_bp, NULL, NULL,
1452 			    ZIO_PRIORITY_ASYNC_READ,
1453 			    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
1454 			    &aflags, &zb);
1455 		}
1456 		mutex_exit(&ds->ds_opening_lock);
1457 	}
1458 
1459 	dsl_dataset_rele(ds, FTAG);
1460 	return (0);
1461 }
1462 
1463 void
1464 dmu_objset_set_user(objset_t *os, void *user_ptr)
1465 {
1466 	ASSERT(MUTEX_HELD(&os->os->os_user_ptr_lock));
1467 	os->os->os_user_ptr = user_ptr;
1468 }
1469 
1470 void *
1471 dmu_objset_get_user(objset_t *os)
1472 {
1473 	ASSERT(MUTEX_HELD(&os->os->os_user_ptr_lock));
1474 	return (os->os->os_user_ptr);
1475 }
1476