xref: /titanic_50/usr/src/uts/common/fs/zfs/dmu_objset.c (revision 22146ea93e24c7deb02c49c33b2ab98605ce78b4)
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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
24  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
25  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
26  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
27  * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
28  * Copyright (c) 2015, STRATO AG, Inc. All rights reserved.
29  */
30 
31 /* Portions Copyright 2010 Robert Milkowski */
32 
33 #include <sys/cred.h>
34 #include <sys/zfs_context.h>
35 #include <sys/dmu_objset.h>
36 #include <sys/dsl_dir.h>
37 #include <sys/dsl_dataset.h>
38 #include <sys/dsl_prop.h>
39 #include <sys/dsl_pool.h>
40 #include <sys/dsl_synctask.h>
41 #include <sys/dsl_deleg.h>
42 #include <sys/dnode.h>
43 #include <sys/dbuf.h>
44 #include <sys/zvol.h>
45 #include <sys/dmu_tx.h>
46 #include <sys/zap.h>
47 #include <sys/zil.h>
48 #include <sys/dmu_impl.h>
49 #include <sys/zfs_ioctl.h>
50 #include <sys/sa.h>
51 #include <sys/zfs_onexit.h>
52 #include <sys/dsl_destroy.h>
53 #include <sys/vdev.h>
54 
55 /*
56  * Needed to close a window in dnode_move() that allows the objset to be freed
57  * before it can be safely accessed.
58  */
59 krwlock_t os_lock;
60 
61 /*
62  * Tunable to overwrite the maximum number of threads for the parallization
63  * of dmu_objset_find_dp, needed to speed up the import of pools with many
64  * datasets.
65  * Default is 4 times the number of leaf vdevs.
66  */
67 int dmu_find_threads = 0;
68 
69 static void dmu_objset_find_dp_cb(void *arg);
70 
71 void
72 dmu_objset_init(void)
73 {
74 	rw_init(&os_lock, NULL, RW_DEFAULT, NULL);
75 }
76 
77 void
78 dmu_objset_fini(void)
79 {
80 	rw_destroy(&os_lock);
81 }
82 
83 spa_t *
84 dmu_objset_spa(objset_t *os)
85 {
86 	return (os->os_spa);
87 }
88 
89 zilog_t *
90 dmu_objset_zil(objset_t *os)
91 {
92 	return (os->os_zil);
93 }
94 
95 dsl_pool_t *
96 dmu_objset_pool(objset_t *os)
97 {
98 	dsl_dataset_t *ds;
99 
100 	if ((ds = os->os_dsl_dataset) != NULL && ds->ds_dir)
101 		return (ds->ds_dir->dd_pool);
102 	else
103 		return (spa_get_dsl(os->os_spa));
104 }
105 
106 dsl_dataset_t *
107 dmu_objset_ds(objset_t *os)
108 {
109 	return (os->os_dsl_dataset);
110 }
111 
112 dmu_objset_type_t
113 dmu_objset_type(objset_t *os)
114 {
115 	return (os->os_phys->os_type);
116 }
117 
118 void
119 dmu_objset_name(objset_t *os, char *buf)
120 {
121 	dsl_dataset_name(os->os_dsl_dataset, buf);
122 }
123 
124 uint64_t
125 dmu_objset_id(objset_t *os)
126 {
127 	dsl_dataset_t *ds = os->os_dsl_dataset;
128 
129 	return (ds ? ds->ds_object : 0);
130 }
131 
132 zfs_sync_type_t
133 dmu_objset_syncprop(objset_t *os)
134 {
135 	return (os->os_sync);
136 }
137 
138 zfs_logbias_op_t
139 dmu_objset_logbias(objset_t *os)
140 {
141 	return (os->os_logbias);
142 }
143 
144 static void
145 checksum_changed_cb(void *arg, uint64_t newval)
146 {
147 	objset_t *os = arg;
148 
149 	/*
150 	 * Inheritance should have been done by now.
151 	 */
152 	ASSERT(newval != ZIO_CHECKSUM_INHERIT);
153 
154 	os->os_checksum = zio_checksum_select(newval, ZIO_CHECKSUM_ON_VALUE);
155 }
156 
157 static void
158 compression_changed_cb(void *arg, uint64_t newval)
159 {
160 	objset_t *os = arg;
161 
162 	/*
163 	 * Inheritance and range checking should have been done by now.
164 	 */
165 	ASSERT(newval != ZIO_COMPRESS_INHERIT);
166 
167 	os->os_compress = zio_compress_select(os->os_spa, newval,
168 	    ZIO_COMPRESS_ON);
169 }
170 
171 static void
172 copies_changed_cb(void *arg, uint64_t newval)
173 {
174 	objset_t *os = arg;
175 
176 	/*
177 	 * Inheritance and range checking should have been done by now.
178 	 */
179 	ASSERT(newval > 0);
180 	ASSERT(newval <= spa_max_replication(os->os_spa));
181 
182 	os->os_copies = newval;
183 }
184 
185 static void
186 dedup_changed_cb(void *arg, uint64_t newval)
187 {
188 	objset_t *os = arg;
189 	spa_t *spa = os->os_spa;
190 	enum zio_checksum checksum;
191 
192 	/*
193 	 * Inheritance should have been done by now.
194 	 */
195 	ASSERT(newval != ZIO_CHECKSUM_INHERIT);
196 
197 	checksum = zio_checksum_dedup_select(spa, newval, ZIO_CHECKSUM_OFF);
198 
199 	os->os_dedup_checksum = checksum & ZIO_CHECKSUM_MASK;
200 	os->os_dedup_verify = !!(checksum & ZIO_CHECKSUM_VERIFY);
201 }
202 
203 static void
204 primary_cache_changed_cb(void *arg, uint64_t newval)
205 {
206 	objset_t *os = arg;
207 
208 	/*
209 	 * Inheritance and range checking should have been done by now.
210 	 */
211 	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
212 	    newval == ZFS_CACHE_METADATA);
213 
214 	os->os_primary_cache = newval;
215 }
216 
217 static void
218 secondary_cache_changed_cb(void *arg, uint64_t newval)
219 {
220 	objset_t *os = arg;
221 
222 	/*
223 	 * Inheritance and range checking should have been done by now.
224 	 */
225 	ASSERT(newval == ZFS_CACHE_ALL || newval == ZFS_CACHE_NONE ||
226 	    newval == ZFS_CACHE_METADATA);
227 
228 	os->os_secondary_cache = newval;
229 }
230 
231 static void
232 sync_changed_cb(void *arg, uint64_t newval)
233 {
234 	objset_t *os = arg;
235 
236 	/*
237 	 * Inheritance and range checking should have been done by now.
238 	 */
239 	ASSERT(newval == ZFS_SYNC_STANDARD || newval == ZFS_SYNC_ALWAYS ||
240 	    newval == ZFS_SYNC_DISABLED);
241 
242 	os->os_sync = newval;
243 	if (os->os_zil)
244 		zil_set_sync(os->os_zil, newval);
245 }
246 
247 static void
248 redundant_metadata_changed_cb(void *arg, uint64_t newval)
249 {
250 	objset_t *os = arg;
251 
252 	/*
253 	 * Inheritance and range checking should have been done by now.
254 	 */
255 	ASSERT(newval == ZFS_REDUNDANT_METADATA_ALL ||
256 	    newval == ZFS_REDUNDANT_METADATA_MOST);
257 
258 	os->os_redundant_metadata = newval;
259 }
260 
261 static void
262 logbias_changed_cb(void *arg, uint64_t newval)
263 {
264 	objset_t *os = arg;
265 
266 	ASSERT(newval == ZFS_LOGBIAS_LATENCY ||
267 	    newval == ZFS_LOGBIAS_THROUGHPUT);
268 	os->os_logbias = newval;
269 	if (os->os_zil)
270 		zil_set_logbias(os->os_zil, newval);
271 }
272 
273 static void
274 recordsize_changed_cb(void *arg, uint64_t newval)
275 {
276 	objset_t *os = arg;
277 
278 	os->os_recordsize = newval;
279 }
280 
281 void
282 dmu_objset_byteswap(void *buf, size_t size)
283 {
284 	objset_phys_t *osp = buf;
285 
286 	ASSERT(size == OBJSET_OLD_PHYS_SIZE || size == sizeof (objset_phys_t));
287 	dnode_byteswap(&osp->os_meta_dnode);
288 	byteswap_uint64_array(&osp->os_zil_header, sizeof (zil_header_t));
289 	osp->os_type = BSWAP_64(osp->os_type);
290 	osp->os_flags = BSWAP_64(osp->os_flags);
291 	if (size == sizeof (objset_phys_t)) {
292 		dnode_byteswap(&osp->os_userused_dnode);
293 		dnode_byteswap(&osp->os_groupused_dnode);
294 	}
295 }
296 
297 int
298 dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
299     objset_t **osp)
300 {
301 	objset_t *os;
302 	int i, err;
303 
304 	ASSERT(ds == NULL || MUTEX_HELD(&ds->ds_opening_lock));
305 
306 	os = kmem_zalloc(sizeof (objset_t), KM_SLEEP);
307 	os->os_dsl_dataset = ds;
308 	os->os_spa = spa;
309 	os->os_rootbp = bp;
310 	if (!BP_IS_HOLE(os->os_rootbp)) {
311 		arc_flags_t aflags = ARC_FLAG_WAIT;
312 		zbookmark_phys_t zb;
313 		SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
314 		    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
315 
316 		if (DMU_OS_IS_L2CACHEABLE(os))
317 			aflags |= ARC_FLAG_L2CACHE;
318 		if (DMU_OS_IS_L2COMPRESSIBLE(os))
319 			aflags |= ARC_FLAG_L2COMPRESS;
320 
321 		dprintf_bp(os->os_rootbp, "reading %s", "");
322 		err = arc_read(NULL, spa, os->os_rootbp,
323 		    arc_getbuf_func, &os->os_phys_buf,
324 		    ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_CANFAIL, &aflags, &zb);
325 		if (err != 0) {
326 			kmem_free(os, sizeof (objset_t));
327 			/* convert checksum errors into IO errors */
328 			if (err == ECKSUM)
329 				err = SET_ERROR(EIO);
330 			return (err);
331 		}
332 
333 		/* Increase the blocksize if we are permitted. */
334 		if (spa_version(spa) >= SPA_VERSION_USERSPACE &&
335 		    arc_buf_size(os->os_phys_buf) < sizeof (objset_phys_t)) {
336 			arc_buf_t *buf = arc_buf_alloc(spa,
337 			    sizeof (objset_phys_t), &os->os_phys_buf,
338 			    ARC_BUFC_METADATA);
339 			bzero(buf->b_data, sizeof (objset_phys_t));
340 			bcopy(os->os_phys_buf->b_data, buf->b_data,
341 			    arc_buf_size(os->os_phys_buf));
342 			(void) arc_buf_remove_ref(os->os_phys_buf,
343 			    &os->os_phys_buf);
344 			os->os_phys_buf = buf;
345 		}
346 
347 		os->os_phys = os->os_phys_buf->b_data;
348 		os->os_flags = os->os_phys->os_flags;
349 	} else {
350 		int size = spa_version(spa) >= SPA_VERSION_USERSPACE ?
351 		    sizeof (objset_phys_t) : OBJSET_OLD_PHYS_SIZE;
352 		os->os_phys_buf = arc_buf_alloc(spa, size,
353 		    &os->os_phys_buf, ARC_BUFC_METADATA);
354 		os->os_phys = os->os_phys_buf->b_data;
355 		bzero(os->os_phys, size);
356 	}
357 
358 	/*
359 	 * Note: the changed_cb will be called once before the register
360 	 * func returns, thus changing the checksum/compression from the
361 	 * default (fletcher2/off).  Snapshots don't need to know about
362 	 * checksum/compression/copies.
363 	 */
364 	if (ds != NULL) {
365 		err = dsl_prop_register(ds,
366 		    zfs_prop_to_name(ZFS_PROP_PRIMARYCACHE),
367 		    primary_cache_changed_cb, os);
368 		if (err == 0) {
369 			err = dsl_prop_register(ds,
370 			    zfs_prop_to_name(ZFS_PROP_SECONDARYCACHE),
371 			    secondary_cache_changed_cb, os);
372 		}
373 		if (!ds->ds_is_snapshot) {
374 			if (err == 0) {
375 				err = dsl_prop_register(ds,
376 				    zfs_prop_to_name(ZFS_PROP_CHECKSUM),
377 				    checksum_changed_cb, os);
378 			}
379 			if (err == 0) {
380 				err = dsl_prop_register(ds,
381 				    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
382 				    compression_changed_cb, os);
383 			}
384 			if (err == 0) {
385 				err = dsl_prop_register(ds,
386 				    zfs_prop_to_name(ZFS_PROP_COPIES),
387 				    copies_changed_cb, os);
388 			}
389 			if (err == 0) {
390 				err = dsl_prop_register(ds,
391 				    zfs_prop_to_name(ZFS_PROP_DEDUP),
392 				    dedup_changed_cb, os);
393 			}
394 			if (err == 0) {
395 				err = dsl_prop_register(ds,
396 				    zfs_prop_to_name(ZFS_PROP_LOGBIAS),
397 				    logbias_changed_cb, os);
398 			}
399 			if (err == 0) {
400 				err = dsl_prop_register(ds,
401 				    zfs_prop_to_name(ZFS_PROP_SYNC),
402 				    sync_changed_cb, os);
403 			}
404 			if (err == 0) {
405 				err = dsl_prop_register(ds,
406 				    zfs_prop_to_name(
407 				    ZFS_PROP_REDUNDANT_METADATA),
408 				    redundant_metadata_changed_cb, os);
409 			}
410 			if (err == 0) {
411 				err = dsl_prop_register(ds,
412 				    zfs_prop_to_name(ZFS_PROP_RECORDSIZE),
413 				    recordsize_changed_cb, os);
414 			}
415 		}
416 		if (err != 0) {
417 			VERIFY(arc_buf_remove_ref(os->os_phys_buf,
418 			    &os->os_phys_buf));
419 			kmem_free(os, sizeof (objset_t));
420 			return (err);
421 		}
422 	} else {
423 		/* It's the meta-objset. */
424 		os->os_checksum = ZIO_CHECKSUM_FLETCHER_4;
425 		os->os_compress = ZIO_COMPRESS_ON;
426 		os->os_copies = spa_max_replication(spa);
427 		os->os_dedup_checksum = ZIO_CHECKSUM_OFF;
428 		os->os_dedup_verify = B_FALSE;
429 		os->os_logbias = ZFS_LOGBIAS_LATENCY;
430 		os->os_sync = ZFS_SYNC_STANDARD;
431 		os->os_primary_cache = ZFS_CACHE_ALL;
432 		os->os_secondary_cache = ZFS_CACHE_ALL;
433 	}
434 
435 	if (ds == NULL || !ds->ds_is_snapshot)
436 		os->os_zil_header = os->os_phys->os_zil_header;
437 	os->os_zil = zil_alloc(os, &os->os_zil_header);
438 
439 	for (i = 0; i < TXG_SIZE; i++) {
440 		list_create(&os->os_dirty_dnodes[i], sizeof (dnode_t),
441 		    offsetof(dnode_t, dn_dirty_link[i]));
442 		list_create(&os->os_free_dnodes[i], sizeof (dnode_t),
443 		    offsetof(dnode_t, dn_dirty_link[i]));
444 	}
445 	list_create(&os->os_dnodes, sizeof (dnode_t),
446 	    offsetof(dnode_t, dn_link));
447 	list_create(&os->os_downgraded_dbufs, sizeof (dmu_buf_impl_t),
448 	    offsetof(dmu_buf_impl_t, db_link));
449 
450 	mutex_init(&os->os_lock, NULL, MUTEX_DEFAULT, NULL);
451 	mutex_init(&os->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
452 	mutex_init(&os->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);
453 
454 	dnode_special_open(os, &os->os_phys->os_meta_dnode,
455 	    DMU_META_DNODE_OBJECT, &os->os_meta_dnode);
456 	if (arc_buf_size(os->os_phys_buf) >= sizeof (objset_phys_t)) {
457 		dnode_special_open(os, &os->os_phys->os_userused_dnode,
458 		    DMU_USERUSED_OBJECT, &os->os_userused_dnode);
459 		dnode_special_open(os, &os->os_phys->os_groupused_dnode,
460 		    DMU_GROUPUSED_OBJECT, &os->os_groupused_dnode);
461 	}
462 
463 	*osp = os;
464 	return (0);
465 }
466 
467 int
468 dmu_objset_from_ds(dsl_dataset_t *ds, objset_t **osp)
469 {
470 	int err = 0;
471 
472 	mutex_enter(&ds->ds_opening_lock);
473 	if (ds->ds_objset == NULL) {
474 		objset_t *os;
475 		err = dmu_objset_open_impl(dsl_dataset_get_spa(ds),
476 		    ds, dsl_dataset_get_blkptr(ds), &os);
477 
478 		if (err == 0) {
479 			mutex_enter(&ds->ds_lock);
480 			ASSERT(ds->ds_objset == NULL);
481 			ds->ds_objset = os;
482 			mutex_exit(&ds->ds_lock);
483 		}
484 	}
485 	*osp = ds->ds_objset;
486 	mutex_exit(&ds->ds_opening_lock);
487 	return (err);
488 }
489 
490 /*
491  * Holds the pool while the objset is held.  Therefore only one objset
492  * can be held at a time.
493  */
494 int
495 dmu_objset_hold(const char *name, void *tag, objset_t **osp)
496 {
497 	dsl_pool_t *dp;
498 	dsl_dataset_t *ds;
499 	int err;
500 
501 	err = dsl_pool_hold(name, tag, &dp);
502 	if (err != 0)
503 		return (err);
504 	err = dsl_dataset_hold(dp, name, tag, &ds);
505 	if (err != 0) {
506 		dsl_pool_rele(dp, tag);
507 		return (err);
508 	}
509 
510 	err = dmu_objset_from_ds(ds, osp);
511 	if (err != 0) {
512 		dsl_dataset_rele(ds, tag);
513 		dsl_pool_rele(dp, tag);
514 	}
515 
516 	return (err);
517 }
518 
519 static int
520 dmu_objset_own_impl(dsl_dataset_t *ds, dmu_objset_type_t type,
521     boolean_t readonly, void *tag, objset_t **osp)
522 {
523 	int err;
524 
525 	err = dmu_objset_from_ds(ds, osp);
526 	if (err != 0) {
527 		dsl_dataset_disown(ds, tag);
528 	} else if (type != DMU_OST_ANY && type != (*osp)->os_phys->os_type) {
529 		dsl_dataset_disown(ds, tag);
530 		return (SET_ERROR(EINVAL));
531 	} else if (!readonly && dsl_dataset_is_snapshot(ds)) {
532 		dsl_dataset_disown(ds, tag);
533 		return (SET_ERROR(EROFS));
534 	}
535 	return (err);
536 }
537 
538 /*
539  * dsl_pool must not be held when this is called.
540  * Upon successful return, there will be a longhold on the dataset,
541  * and the dsl_pool will not be held.
542  */
543 int
544 dmu_objset_own(const char *name, dmu_objset_type_t type,
545     boolean_t readonly, void *tag, objset_t **osp)
546 {
547 	dsl_pool_t *dp;
548 	dsl_dataset_t *ds;
549 	int err;
550 
551 	err = dsl_pool_hold(name, FTAG, &dp);
552 	if (err != 0)
553 		return (err);
554 	err = dsl_dataset_own(dp, name, tag, &ds);
555 	if (err != 0) {
556 		dsl_pool_rele(dp, FTAG);
557 		return (err);
558 	}
559 	err = dmu_objset_own_impl(ds, type, readonly, tag, osp);
560 	dsl_pool_rele(dp, FTAG);
561 
562 	return (err);
563 }
564 
565 int
566 dmu_objset_own_obj(dsl_pool_t *dp, uint64_t obj, dmu_objset_type_t type,
567     boolean_t readonly, void *tag, objset_t **osp)
568 {
569 	dsl_dataset_t *ds;
570 	int err;
571 
572 	err = dsl_dataset_own_obj(dp, obj, tag, &ds);
573 	if (err != 0)
574 		return (err);
575 
576 	return (dmu_objset_own_impl(ds, type, readonly, tag, osp));
577 }
578 
579 void
580 dmu_objset_rele(objset_t *os, void *tag)
581 {
582 	dsl_pool_t *dp = dmu_objset_pool(os);
583 	dsl_dataset_rele(os->os_dsl_dataset, tag);
584 	dsl_pool_rele(dp, tag);
585 }
586 
587 /*
588  * When we are called, os MUST refer to an objset associated with a dataset
589  * that is owned by 'tag'; that is, is held and long held by 'tag' and ds_owner
590  * == tag.  We will then release and reacquire ownership of the dataset while
591  * holding the pool config_rwlock to avoid intervening namespace or ownership
592  * changes may occur.
593  *
594  * This exists solely to accommodate zfs_ioc_userspace_upgrade()'s desire to
595  * release the hold on its dataset and acquire a new one on the dataset of the
596  * same name so that it can be partially torn down and reconstructed.
597  */
598 void
599 dmu_objset_refresh_ownership(objset_t *os, void *tag)
600 {
601 	dsl_pool_t *dp;
602 	dsl_dataset_t *ds, *newds;
603 	char name[MAXNAMELEN];
604 
605 	ds = os->os_dsl_dataset;
606 	VERIFY3P(ds, !=, NULL);
607 	VERIFY3P(ds->ds_owner, ==, tag);
608 	VERIFY(dsl_dataset_long_held(ds));
609 
610 	dsl_dataset_name(ds, name);
611 	dp = dmu_objset_pool(os);
612 	dsl_pool_config_enter(dp, FTAG);
613 	dmu_objset_disown(os, tag);
614 	VERIFY0(dsl_dataset_own(dp, name, tag, &newds));
615 	VERIFY3P(newds, ==, os->os_dsl_dataset);
616 	dsl_pool_config_exit(dp, FTAG);
617 }
618 
619 void
620 dmu_objset_disown(objset_t *os, void *tag)
621 {
622 	dsl_dataset_disown(os->os_dsl_dataset, tag);
623 }
624 
625 void
626 dmu_objset_evict_dbufs(objset_t *os)
627 {
628 	dnode_t dn_marker;
629 	dnode_t *dn;
630 
631 	mutex_enter(&os->os_lock);
632 	dn = list_head(&os->os_dnodes);
633 	while (dn != NULL) {
634 		/*
635 		 * Skip dnodes without holds.  We have to do this dance
636 		 * because dnode_add_ref() only works if there is already a
637 		 * hold.  If the dnode has no holds, then it has no dbufs.
638 		 */
639 		if (dnode_add_ref(dn, FTAG)) {
640 			list_insert_after(&os->os_dnodes, dn, &dn_marker);
641 			mutex_exit(&os->os_lock);
642 
643 			dnode_evict_dbufs(dn);
644 			dnode_rele(dn, FTAG);
645 
646 			mutex_enter(&os->os_lock);
647 			dn = list_next(&os->os_dnodes, &dn_marker);
648 			list_remove(&os->os_dnodes, &dn_marker);
649 		} else {
650 			dn = list_next(&os->os_dnodes, dn);
651 		}
652 	}
653 	mutex_exit(&os->os_lock);
654 
655 	if (DMU_USERUSED_DNODE(os) != NULL) {
656 		dnode_evict_dbufs(DMU_GROUPUSED_DNODE(os));
657 		dnode_evict_dbufs(DMU_USERUSED_DNODE(os));
658 	}
659 	dnode_evict_dbufs(DMU_META_DNODE(os));
660 }
661 
662 /*
663  * Objset eviction processing is split into into two pieces.
664  * The first marks the objset as evicting, evicts any dbufs that
665  * have a refcount of zero, and then queues up the objset for the
666  * second phase of eviction.  Once os->os_dnodes has been cleared by
667  * dnode_buf_pageout()->dnode_destroy(), the second phase is executed.
668  * The second phase closes the special dnodes, dequeues the objset from
669  * the list of those undergoing eviction, and finally frees the objset.
670  *
671  * NOTE: Due to asynchronous eviction processing (invocation of
672  *       dnode_buf_pageout()), it is possible for the meta dnode for the
673  *       objset to have no holds even though os->os_dnodes is not empty.
674  */
675 void
676 dmu_objset_evict(objset_t *os)
677 {
678 	dsl_dataset_t *ds = os->os_dsl_dataset;
679 
680 	for (int t = 0; t < TXG_SIZE; t++)
681 		ASSERT(!dmu_objset_is_dirty(os, t));
682 
683 	if (ds) {
684 		if (!ds->ds_is_snapshot) {
685 			VERIFY0(dsl_prop_unregister(ds,
686 			    zfs_prop_to_name(ZFS_PROP_CHECKSUM),
687 			    checksum_changed_cb, os));
688 			VERIFY0(dsl_prop_unregister(ds,
689 			    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
690 			    compression_changed_cb, os));
691 			VERIFY0(dsl_prop_unregister(ds,
692 			    zfs_prop_to_name(ZFS_PROP_COPIES),
693 			    copies_changed_cb, os));
694 			VERIFY0(dsl_prop_unregister(ds,
695 			    zfs_prop_to_name(ZFS_PROP_DEDUP),
696 			    dedup_changed_cb, os));
697 			VERIFY0(dsl_prop_unregister(ds,
698 			    zfs_prop_to_name(ZFS_PROP_LOGBIAS),
699 			    logbias_changed_cb, os));
700 			VERIFY0(dsl_prop_unregister(ds,
701 			    zfs_prop_to_name(ZFS_PROP_SYNC),
702 			    sync_changed_cb, os));
703 			VERIFY0(dsl_prop_unregister(ds,
704 			    zfs_prop_to_name(ZFS_PROP_REDUNDANT_METADATA),
705 			    redundant_metadata_changed_cb, os));
706 			VERIFY0(dsl_prop_unregister(ds,
707 			    zfs_prop_to_name(ZFS_PROP_RECORDSIZE),
708 			    recordsize_changed_cb, os));
709 		}
710 		VERIFY0(dsl_prop_unregister(ds,
711 		    zfs_prop_to_name(ZFS_PROP_PRIMARYCACHE),
712 		    primary_cache_changed_cb, os));
713 		VERIFY0(dsl_prop_unregister(ds,
714 		    zfs_prop_to_name(ZFS_PROP_SECONDARYCACHE),
715 		    secondary_cache_changed_cb, os));
716 	}
717 
718 	if (os->os_sa)
719 		sa_tear_down(os);
720 
721 	os->os_evicting = B_TRUE;
722 	dmu_objset_evict_dbufs(os);
723 
724 	mutex_enter(&os->os_lock);
725 	spa_evicting_os_register(os->os_spa, os);
726 	if (list_is_empty(&os->os_dnodes)) {
727 		mutex_exit(&os->os_lock);
728 		dmu_objset_evict_done(os);
729 	} else {
730 		mutex_exit(&os->os_lock);
731 	}
732 }
733 
734 void
735 dmu_objset_evict_done(objset_t *os)
736 {
737 	ASSERT3P(list_head(&os->os_dnodes), ==, NULL);
738 
739 	dnode_special_close(&os->os_meta_dnode);
740 	if (DMU_USERUSED_DNODE(os)) {
741 		dnode_special_close(&os->os_userused_dnode);
742 		dnode_special_close(&os->os_groupused_dnode);
743 	}
744 	zil_free(os->os_zil);
745 
746 	VERIFY(arc_buf_remove_ref(os->os_phys_buf, &os->os_phys_buf));
747 
748 	/*
749 	 * This is a barrier to prevent the objset from going away in
750 	 * dnode_move() until we can safely ensure that the objset is still in
751 	 * use. We consider the objset valid before the barrier and invalid
752 	 * after the barrier.
753 	 */
754 	rw_enter(&os_lock, RW_READER);
755 	rw_exit(&os_lock);
756 
757 	mutex_destroy(&os->os_lock);
758 	mutex_destroy(&os->os_obj_lock);
759 	mutex_destroy(&os->os_user_ptr_lock);
760 	spa_evicting_os_deregister(os->os_spa, os);
761 	kmem_free(os, sizeof (objset_t));
762 }
763 
764 timestruc_t
765 dmu_objset_snap_cmtime(objset_t *os)
766 {
767 	return (dsl_dir_snap_cmtime(os->os_dsl_dataset->ds_dir));
768 }
769 
770 /* called from dsl for meta-objset */
771 objset_t *
772 dmu_objset_create_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
773     dmu_objset_type_t type, dmu_tx_t *tx)
774 {
775 	objset_t *os;
776 	dnode_t *mdn;
777 
778 	ASSERT(dmu_tx_is_syncing(tx));
779 
780 	if (ds != NULL)
781 		VERIFY0(dmu_objset_from_ds(ds, &os));
782 	else
783 		VERIFY0(dmu_objset_open_impl(spa, NULL, bp, &os));
784 
785 	mdn = DMU_META_DNODE(os);
786 
787 	dnode_allocate(mdn, DMU_OT_DNODE, 1 << DNODE_BLOCK_SHIFT,
788 	    DN_MAX_INDBLKSHIFT, DMU_OT_NONE, 0, tx);
789 
790 	/*
791 	 * We don't want to have to increase the meta-dnode's nlevels
792 	 * later, because then we could do it in quescing context while
793 	 * we are also accessing it in open context.
794 	 *
795 	 * This precaution is not necessary for the MOS (ds == NULL),
796 	 * because the MOS is only updated in syncing context.
797 	 * This is most fortunate: the MOS is the only objset that
798 	 * needs to be synced multiple times as spa_sync() iterates
799 	 * to convergence, so minimizing its dn_nlevels matters.
800 	 */
801 	if (ds != NULL) {
802 		int levels = 1;
803 
804 		/*
805 		 * Determine the number of levels necessary for the meta-dnode
806 		 * to contain DN_MAX_OBJECT dnodes.
807 		 */
808 		while ((uint64_t)mdn->dn_nblkptr << (mdn->dn_datablkshift +
809 		    (levels - 1) * (mdn->dn_indblkshift - SPA_BLKPTRSHIFT)) <
810 		    DN_MAX_OBJECT * sizeof (dnode_phys_t))
811 			levels++;
812 
813 		mdn->dn_next_nlevels[tx->tx_txg & TXG_MASK] =
814 		    mdn->dn_nlevels = levels;
815 	}
816 
817 	ASSERT(type != DMU_OST_NONE);
818 	ASSERT(type != DMU_OST_ANY);
819 	ASSERT(type < DMU_OST_NUMTYPES);
820 	os->os_phys->os_type = type;
821 	if (dmu_objset_userused_enabled(os)) {
822 		os->os_phys->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
823 		os->os_flags = os->os_phys->os_flags;
824 	}
825 
826 	dsl_dataset_dirty(ds, tx);
827 
828 	return (os);
829 }
830 
831 typedef struct dmu_objset_create_arg {
832 	const char *doca_name;
833 	cred_t *doca_cred;
834 	void (*doca_userfunc)(objset_t *os, void *arg,
835 	    cred_t *cr, dmu_tx_t *tx);
836 	void *doca_userarg;
837 	dmu_objset_type_t doca_type;
838 	uint64_t doca_flags;
839 } dmu_objset_create_arg_t;
840 
841 /*ARGSUSED*/
842 static int
843 dmu_objset_create_check(void *arg, dmu_tx_t *tx)
844 {
845 	dmu_objset_create_arg_t *doca = arg;
846 	dsl_pool_t *dp = dmu_tx_pool(tx);
847 	dsl_dir_t *pdd;
848 	const char *tail;
849 	int error;
850 
851 	if (strchr(doca->doca_name, '@') != NULL)
852 		return (SET_ERROR(EINVAL));
853 
854 	error = dsl_dir_hold(dp, doca->doca_name, FTAG, &pdd, &tail);
855 	if (error != 0)
856 		return (error);
857 	if (tail == NULL) {
858 		dsl_dir_rele(pdd, FTAG);
859 		return (SET_ERROR(EEXIST));
860 	}
861 	error = dsl_fs_ss_limit_check(pdd, 1, ZFS_PROP_FILESYSTEM_LIMIT, NULL,
862 	    doca->doca_cred);
863 	dsl_dir_rele(pdd, FTAG);
864 
865 	return (error);
866 }
867 
868 static void
869 dmu_objset_create_sync(void *arg, dmu_tx_t *tx)
870 {
871 	dmu_objset_create_arg_t *doca = arg;
872 	dsl_pool_t *dp = dmu_tx_pool(tx);
873 	dsl_dir_t *pdd;
874 	const char *tail;
875 	dsl_dataset_t *ds;
876 	uint64_t obj;
877 	blkptr_t *bp;
878 	objset_t *os;
879 
880 	VERIFY0(dsl_dir_hold(dp, doca->doca_name, FTAG, &pdd, &tail));
881 
882 	obj = dsl_dataset_create_sync(pdd, tail, NULL, doca->doca_flags,
883 	    doca->doca_cred, tx);
884 
885 	VERIFY0(dsl_dataset_hold_obj(pdd->dd_pool, obj, FTAG, &ds));
886 	bp = dsl_dataset_get_blkptr(ds);
887 	os = dmu_objset_create_impl(pdd->dd_pool->dp_spa,
888 	    ds, bp, doca->doca_type, tx);
889 
890 	if (doca->doca_userfunc != NULL) {
891 		doca->doca_userfunc(os, doca->doca_userarg,
892 		    doca->doca_cred, tx);
893 	}
894 
895 	spa_history_log_internal_ds(ds, "create", tx, "");
896 	dsl_dataset_rele(ds, FTAG);
897 	dsl_dir_rele(pdd, FTAG);
898 }
899 
900 int
901 dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
902     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg)
903 {
904 	dmu_objset_create_arg_t doca;
905 
906 	doca.doca_name = name;
907 	doca.doca_cred = CRED();
908 	doca.doca_flags = flags;
909 	doca.doca_userfunc = func;
910 	doca.doca_userarg = arg;
911 	doca.doca_type = type;
912 
913 	return (dsl_sync_task(name,
914 	    dmu_objset_create_check, dmu_objset_create_sync, &doca,
915 	    5, ZFS_SPACE_CHECK_NORMAL));
916 }
917 
918 typedef struct dmu_objset_clone_arg {
919 	const char *doca_clone;
920 	const char *doca_origin;
921 	cred_t *doca_cred;
922 } dmu_objset_clone_arg_t;
923 
924 /*ARGSUSED*/
925 static int
926 dmu_objset_clone_check(void *arg, dmu_tx_t *tx)
927 {
928 	dmu_objset_clone_arg_t *doca = arg;
929 	dsl_dir_t *pdd;
930 	const char *tail;
931 	int error;
932 	dsl_dataset_t *origin;
933 	dsl_pool_t *dp = dmu_tx_pool(tx);
934 
935 	if (strchr(doca->doca_clone, '@') != NULL)
936 		return (SET_ERROR(EINVAL));
937 
938 	error = dsl_dir_hold(dp, doca->doca_clone, FTAG, &pdd, &tail);
939 	if (error != 0)
940 		return (error);
941 	if (tail == NULL) {
942 		dsl_dir_rele(pdd, FTAG);
943 		return (SET_ERROR(EEXIST));
944 	}
945 
946 	error = dsl_fs_ss_limit_check(pdd, 1, ZFS_PROP_FILESYSTEM_LIMIT, NULL,
947 	    doca->doca_cred);
948 	if (error != 0) {
949 		dsl_dir_rele(pdd, FTAG);
950 		return (SET_ERROR(EDQUOT));
951 	}
952 	dsl_dir_rele(pdd, FTAG);
953 
954 	error = dsl_dataset_hold(dp, doca->doca_origin, FTAG, &origin);
955 	if (error != 0)
956 		return (error);
957 
958 	/* You can only clone snapshots, not the head datasets. */
959 	if (!origin->ds_is_snapshot) {
960 		dsl_dataset_rele(origin, FTAG);
961 		return (SET_ERROR(EINVAL));
962 	}
963 	dsl_dataset_rele(origin, FTAG);
964 
965 	return (0);
966 }
967 
968 static void
969 dmu_objset_clone_sync(void *arg, dmu_tx_t *tx)
970 {
971 	dmu_objset_clone_arg_t *doca = arg;
972 	dsl_pool_t *dp = dmu_tx_pool(tx);
973 	dsl_dir_t *pdd;
974 	const char *tail;
975 	dsl_dataset_t *origin, *ds;
976 	uint64_t obj;
977 	char namebuf[MAXNAMELEN];
978 
979 	VERIFY0(dsl_dir_hold(dp, doca->doca_clone, FTAG, &pdd, &tail));
980 	VERIFY0(dsl_dataset_hold(dp, doca->doca_origin, FTAG, &origin));
981 
982 	obj = dsl_dataset_create_sync(pdd, tail, origin, 0,
983 	    doca->doca_cred, tx);
984 
985 	VERIFY0(dsl_dataset_hold_obj(pdd->dd_pool, obj, FTAG, &ds));
986 	dsl_dataset_name(origin, namebuf);
987 	spa_history_log_internal_ds(ds, "clone", tx,
988 	    "origin=%s (%llu)", namebuf, origin->ds_object);
989 	dsl_dataset_rele(ds, FTAG);
990 	dsl_dataset_rele(origin, FTAG);
991 	dsl_dir_rele(pdd, FTAG);
992 }
993 
994 int
995 dmu_objset_clone(const char *clone, const char *origin)
996 {
997 	dmu_objset_clone_arg_t doca;
998 
999 	doca.doca_clone = clone;
1000 	doca.doca_origin = origin;
1001 	doca.doca_cred = CRED();
1002 
1003 	return (dsl_sync_task(clone,
1004 	    dmu_objset_clone_check, dmu_objset_clone_sync, &doca,
1005 	    5, ZFS_SPACE_CHECK_NORMAL));
1006 }
1007 
1008 int
1009 dmu_objset_snapshot_one(const char *fsname, const char *snapname)
1010 {
1011 	int err;
1012 	char *longsnap = kmem_asprintf("%s@%s", fsname, snapname);
1013 	nvlist_t *snaps = fnvlist_alloc();
1014 
1015 	fnvlist_add_boolean(snaps, longsnap);
1016 	strfree(longsnap);
1017 	err = dsl_dataset_snapshot(snaps, NULL, NULL);
1018 	fnvlist_free(snaps);
1019 	return (err);
1020 }
1021 
1022 static void
1023 dmu_objset_sync_dnodes(list_t *list, list_t *newlist, dmu_tx_t *tx)
1024 {
1025 	dnode_t *dn;
1026 
1027 	while (dn = list_head(list)) {
1028 		ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
1029 		ASSERT(dn->dn_dbuf->db_data_pending);
1030 		/*
1031 		 * Initialize dn_zio outside dnode_sync() because the
1032 		 * meta-dnode needs to set it ouside dnode_sync().
1033 		 */
1034 		dn->dn_zio = dn->dn_dbuf->db_data_pending->dr_zio;
1035 		ASSERT(dn->dn_zio);
1036 
1037 		ASSERT3U(dn->dn_nlevels, <=, DN_MAX_LEVELS);
1038 		list_remove(list, dn);
1039 
1040 		if (newlist) {
1041 			(void) dnode_add_ref(dn, newlist);
1042 			list_insert_tail(newlist, dn);
1043 		}
1044 
1045 		dnode_sync(dn, tx);
1046 	}
1047 }
1048 
1049 /* ARGSUSED */
1050 static void
1051 dmu_objset_write_ready(zio_t *zio, arc_buf_t *abuf, void *arg)
1052 {
1053 	blkptr_t *bp = zio->io_bp;
1054 	objset_t *os = arg;
1055 	dnode_phys_t *dnp = &os->os_phys->os_meta_dnode;
1056 
1057 	ASSERT(!BP_IS_EMBEDDED(bp));
1058 	ASSERT3P(bp, ==, os->os_rootbp);
1059 	ASSERT3U(BP_GET_TYPE(bp), ==, DMU_OT_OBJSET);
1060 	ASSERT0(BP_GET_LEVEL(bp));
1061 
1062 	/*
1063 	 * Update rootbp fill count: it should be the number of objects
1064 	 * allocated in the object set (not counting the "special"
1065 	 * objects that are stored in the objset_phys_t -- the meta
1066 	 * dnode and user/group accounting objects).
1067 	 */
1068 	bp->blk_fill = 0;
1069 	for (int i = 0; i < dnp->dn_nblkptr; i++)
1070 		bp->blk_fill += BP_GET_FILL(&dnp->dn_blkptr[i]);
1071 }
1072 
1073 /* ARGSUSED */
1074 static void
1075 dmu_objset_write_done(zio_t *zio, arc_buf_t *abuf, void *arg)
1076 {
1077 	blkptr_t *bp = zio->io_bp;
1078 	blkptr_t *bp_orig = &zio->io_bp_orig;
1079 	objset_t *os = arg;
1080 
1081 	if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
1082 		ASSERT(BP_EQUAL(bp, bp_orig));
1083 	} else {
1084 		dsl_dataset_t *ds = os->os_dsl_dataset;
1085 		dmu_tx_t *tx = os->os_synctx;
1086 
1087 		(void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
1088 		dsl_dataset_block_born(ds, bp, tx);
1089 	}
1090 }
1091 
1092 /* called from dsl */
1093 void
1094 dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx)
1095 {
1096 	int txgoff;
1097 	zbookmark_phys_t zb;
1098 	zio_prop_t zp;
1099 	zio_t *zio;
1100 	list_t *list;
1101 	list_t *newlist = NULL;
1102 	dbuf_dirty_record_t *dr;
1103 
1104 	dprintf_ds(os->os_dsl_dataset, "txg=%llu\n", tx->tx_txg);
1105 
1106 	ASSERT(dmu_tx_is_syncing(tx));
1107 	/* XXX the write_done callback should really give us the tx... */
1108 	os->os_synctx = tx;
1109 
1110 	if (os->os_dsl_dataset == NULL) {
1111 		/*
1112 		 * This is the MOS.  If we have upgraded,
1113 		 * spa_max_replication() could change, so reset
1114 		 * os_copies here.
1115 		 */
1116 		os->os_copies = spa_max_replication(os->os_spa);
1117 	}
1118 
1119 	/*
1120 	 * Create the root block IO
1121 	 */
1122 	SET_BOOKMARK(&zb, os->os_dsl_dataset ?
1123 	    os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
1124 	    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
1125 	arc_release(os->os_phys_buf, &os->os_phys_buf);
1126 
1127 	dmu_write_policy(os, NULL, 0, 0, &zp);
1128 
1129 	zio = arc_write(pio, os->os_spa, tx->tx_txg,
1130 	    os->os_rootbp, os->os_phys_buf, DMU_OS_IS_L2CACHEABLE(os),
1131 	    DMU_OS_IS_L2COMPRESSIBLE(os), &zp, dmu_objset_write_ready,
1132 	    NULL, dmu_objset_write_done, os, ZIO_PRIORITY_ASYNC_WRITE,
1133 	    ZIO_FLAG_MUSTSUCCEED, &zb);
1134 
1135 	/*
1136 	 * Sync special dnodes - the parent IO for the sync is the root block
1137 	 */
1138 	DMU_META_DNODE(os)->dn_zio = zio;
1139 	dnode_sync(DMU_META_DNODE(os), tx);
1140 
1141 	os->os_phys->os_flags = os->os_flags;
1142 
1143 	if (DMU_USERUSED_DNODE(os) &&
1144 	    DMU_USERUSED_DNODE(os)->dn_type != DMU_OT_NONE) {
1145 		DMU_USERUSED_DNODE(os)->dn_zio = zio;
1146 		dnode_sync(DMU_USERUSED_DNODE(os), tx);
1147 		DMU_GROUPUSED_DNODE(os)->dn_zio = zio;
1148 		dnode_sync(DMU_GROUPUSED_DNODE(os), tx);
1149 	}
1150 
1151 	txgoff = tx->tx_txg & TXG_MASK;
1152 
1153 	if (dmu_objset_userused_enabled(os)) {
1154 		newlist = &os->os_synced_dnodes;
1155 		/*
1156 		 * We must create the list here because it uses the
1157 		 * dn_dirty_link[] of this txg.
1158 		 */
1159 		list_create(newlist, sizeof (dnode_t),
1160 		    offsetof(dnode_t, dn_dirty_link[txgoff]));
1161 	}
1162 
1163 	dmu_objset_sync_dnodes(&os->os_free_dnodes[txgoff], newlist, tx);
1164 	dmu_objset_sync_dnodes(&os->os_dirty_dnodes[txgoff], newlist, tx);
1165 
1166 	list = &DMU_META_DNODE(os)->dn_dirty_records[txgoff];
1167 	while (dr = list_head(list)) {
1168 		ASSERT0(dr->dr_dbuf->db_level);
1169 		list_remove(list, dr);
1170 		if (dr->dr_zio)
1171 			zio_nowait(dr->dr_zio);
1172 	}
1173 	/*
1174 	 * Free intent log blocks up to this tx.
1175 	 */
1176 	zil_sync(os->os_zil, tx);
1177 	os->os_phys->os_zil_header = os->os_zil_header;
1178 	zio_nowait(zio);
1179 }
1180 
1181 boolean_t
1182 dmu_objset_is_dirty(objset_t *os, uint64_t txg)
1183 {
1184 	return (!list_is_empty(&os->os_dirty_dnodes[txg & TXG_MASK]) ||
1185 	    !list_is_empty(&os->os_free_dnodes[txg & TXG_MASK]));
1186 }
1187 
1188 static objset_used_cb_t *used_cbs[DMU_OST_NUMTYPES];
1189 
1190 void
1191 dmu_objset_register_type(dmu_objset_type_t ost, objset_used_cb_t *cb)
1192 {
1193 	used_cbs[ost] = cb;
1194 }
1195 
1196 boolean_t
1197 dmu_objset_userused_enabled(objset_t *os)
1198 {
1199 	return (spa_version(os->os_spa) >= SPA_VERSION_USERSPACE &&
1200 	    used_cbs[os->os_phys->os_type] != NULL &&
1201 	    DMU_USERUSED_DNODE(os) != NULL);
1202 }
1203 
1204 static void
1205 do_userquota_update(objset_t *os, uint64_t used, uint64_t flags,
1206     uint64_t user, uint64_t group, boolean_t subtract, dmu_tx_t *tx)
1207 {
1208 	if ((flags & DNODE_FLAG_USERUSED_ACCOUNTED)) {
1209 		int64_t delta = DNODE_SIZE + used;
1210 		if (subtract)
1211 			delta = -delta;
1212 		VERIFY3U(0, ==, zap_increment_int(os, DMU_USERUSED_OBJECT,
1213 		    user, delta, tx));
1214 		VERIFY3U(0, ==, zap_increment_int(os, DMU_GROUPUSED_OBJECT,
1215 		    group, delta, tx));
1216 	}
1217 }
1218 
1219 void
1220 dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
1221 {
1222 	dnode_t *dn;
1223 	list_t *list = &os->os_synced_dnodes;
1224 
1225 	ASSERT(list_head(list) == NULL || dmu_objset_userused_enabled(os));
1226 
1227 	while (dn = list_head(list)) {
1228 		int flags;
1229 		ASSERT(!DMU_OBJECT_IS_SPECIAL(dn->dn_object));
1230 		ASSERT(dn->dn_phys->dn_type == DMU_OT_NONE ||
1231 		    dn->dn_phys->dn_flags &
1232 		    DNODE_FLAG_USERUSED_ACCOUNTED);
1233 
1234 		/* Allocate the user/groupused objects if necessary. */
1235 		if (DMU_USERUSED_DNODE(os)->dn_type == DMU_OT_NONE) {
1236 			VERIFY(0 == zap_create_claim(os,
1237 			    DMU_USERUSED_OBJECT,
1238 			    DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
1239 			VERIFY(0 == zap_create_claim(os,
1240 			    DMU_GROUPUSED_OBJECT,
1241 			    DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
1242 		}
1243 
1244 		/*
1245 		 * We intentionally modify the zap object even if the
1246 		 * net delta is zero.  Otherwise
1247 		 * the block of the zap obj could be shared between
1248 		 * datasets but need to be different between them after
1249 		 * a bprewrite.
1250 		 */
1251 
1252 		flags = dn->dn_id_flags;
1253 		ASSERT(flags);
1254 		if (flags & DN_ID_OLD_EXIST)  {
1255 			do_userquota_update(os, dn->dn_oldused, dn->dn_oldflags,
1256 			    dn->dn_olduid, dn->dn_oldgid, B_TRUE, tx);
1257 		}
1258 		if (flags & DN_ID_NEW_EXIST) {
1259 			do_userquota_update(os, DN_USED_BYTES(dn->dn_phys),
1260 			    dn->dn_phys->dn_flags,  dn->dn_newuid,
1261 			    dn->dn_newgid, B_FALSE, tx);
1262 		}
1263 
1264 		mutex_enter(&dn->dn_mtx);
1265 		dn->dn_oldused = 0;
1266 		dn->dn_oldflags = 0;
1267 		if (dn->dn_id_flags & DN_ID_NEW_EXIST) {
1268 			dn->dn_olduid = dn->dn_newuid;
1269 			dn->dn_oldgid = dn->dn_newgid;
1270 			dn->dn_id_flags |= DN_ID_OLD_EXIST;
1271 			if (dn->dn_bonuslen == 0)
1272 				dn->dn_id_flags |= DN_ID_CHKED_SPILL;
1273 			else
1274 				dn->dn_id_flags |= DN_ID_CHKED_BONUS;
1275 		}
1276 		dn->dn_id_flags &= ~(DN_ID_NEW_EXIST);
1277 		mutex_exit(&dn->dn_mtx);
1278 
1279 		list_remove(list, dn);
1280 		dnode_rele(dn, list);
1281 	}
1282 }
1283 
1284 /*
1285  * Returns a pointer to data to find uid/gid from
1286  *
1287  * If a dirty record for transaction group that is syncing can't
1288  * be found then NULL is returned.  In the NULL case it is assumed
1289  * the uid/gid aren't changing.
1290  */
1291 static void *
1292 dmu_objset_userquota_find_data(dmu_buf_impl_t *db, dmu_tx_t *tx)
1293 {
1294 	dbuf_dirty_record_t *dr, **drp;
1295 	void *data;
1296 
1297 	if (db->db_dirtycnt == 0)
1298 		return (db->db.db_data);  /* Nothing is changing */
1299 
1300 	for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1301 		if (dr->dr_txg == tx->tx_txg)
1302 			break;
1303 
1304 	if (dr == NULL) {
1305 		data = NULL;
1306 	} else {
1307 		dnode_t *dn;
1308 
1309 		DB_DNODE_ENTER(dr->dr_dbuf);
1310 		dn = DB_DNODE(dr->dr_dbuf);
1311 
1312 		if (dn->dn_bonuslen == 0 &&
1313 		    dr->dr_dbuf->db_blkid == DMU_SPILL_BLKID)
1314 			data = dr->dt.dl.dr_data->b_data;
1315 		else
1316 			data = dr->dt.dl.dr_data;
1317 
1318 		DB_DNODE_EXIT(dr->dr_dbuf);
1319 	}
1320 
1321 	return (data);
1322 }
1323 
1324 void
1325 dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx)
1326 {
1327 	objset_t *os = dn->dn_objset;
1328 	void *data = NULL;
1329 	dmu_buf_impl_t *db = NULL;
1330 	uint64_t *user = NULL;
1331 	uint64_t *group = NULL;
1332 	int flags = dn->dn_id_flags;
1333 	int error;
1334 	boolean_t have_spill = B_FALSE;
1335 
1336 	if (!dmu_objset_userused_enabled(dn->dn_objset))
1337 		return;
1338 
1339 	if (before && (flags & (DN_ID_CHKED_BONUS|DN_ID_OLD_EXIST|
1340 	    DN_ID_CHKED_SPILL)))
1341 		return;
1342 
1343 	if (before && dn->dn_bonuslen != 0)
1344 		data = DN_BONUS(dn->dn_phys);
1345 	else if (!before && dn->dn_bonuslen != 0) {
1346 		if (dn->dn_bonus) {
1347 			db = dn->dn_bonus;
1348 			mutex_enter(&db->db_mtx);
1349 			data = dmu_objset_userquota_find_data(db, tx);
1350 		} else {
1351 			data = DN_BONUS(dn->dn_phys);
1352 		}
1353 	} else if (dn->dn_bonuslen == 0 && dn->dn_bonustype == DMU_OT_SA) {
1354 			int rf = 0;
1355 
1356 			if (RW_WRITE_HELD(&dn->dn_struct_rwlock))
1357 				rf |= DB_RF_HAVESTRUCT;
1358 			error = dmu_spill_hold_by_dnode(dn,
1359 			    rf | DB_RF_MUST_SUCCEED,
1360 			    FTAG, (dmu_buf_t **)&db);
1361 			ASSERT(error == 0);
1362 			mutex_enter(&db->db_mtx);
1363 			data = (before) ? db->db.db_data :
1364 			    dmu_objset_userquota_find_data(db, tx);
1365 			have_spill = B_TRUE;
1366 	} else {
1367 		mutex_enter(&dn->dn_mtx);
1368 		dn->dn_id_flags |= DN_ID_CHKED_BONUS;
1369 		mutex_exit(&dn->dn_mtx);
1370 		return;
1371 	}
1372 
1373 	if (before) {
1374 		ASSERT(data);
1375 		user = &dn->dn_olduid;
1376 		group = &dn->dn_oldgid;
1377 	} else if (data) {
1378 		user = &dn->dn_newuid;
1379 		group = &dn->dn_newgid;
1380 	}
1381 
1382 	/*
1383 	 * Must always call the callback in case the object
1384 	 * type has changed and that type isn't an object type to track
1385 	 */
1386 	error = used_cbs[os->os_phys->os_type](dn->dn_bonustype, data,
1387 	    user, group);
1388 
1389 	/*
1390 	 * Preserve existing uid/gid when the callback can't determine
1391 	 * what the new uid/gid are and the callback returned EEXIST.
1392 	 * The EEXIST error tells us to just use the existing uid/gid.
1393 	 * If we don't know what the old values are then just assign
1394 	 * them to 0, since that is a new file  being created.
1395 	 */
1396 	if (!before && data == NULL && error == EEXIST) {
1397 		if (flags & DN_ID_OLD_EXIST) {
1398 			dn->dn_newuid = dn->dn_olduid;
1399 			dn->dn_newgid = dn->dn_oldgid;
1400 		} else {
1401 			dn->dn_newuid = 0;
1402 			dn->dn_newgid = 0;
1403 		}
1404 		error = 0;
1405 	}
1406 
1407 	if (db)
1408 		mutex_exit(&db->db_mtx);
1409 
1410 	mutex_enter(&dn->dn_mtx);
1411 	if (error == 0 && before)
1412 		dn->dn_id_flags |= DN_ID_OLD_EXIST;
1413 	if (error == 0 && !before)
1414 		dn->dn_id_flags |= DN_ID_NEW_EXIST;
1415 
1416 	if (have_spill) {
1417 		dn->dn_id_flags |= DN_ID_CHKED_SPILL;
1418 	} else {
1419 		dn->dn_id_flags |= DN_ID_CHKED_BONUS;
1420 	}
1421 	mutex_exit(&dn->dn_mtx);
1422 	if (have_spill)
1423 		dmu_buf_rele((dmu_buf_t *)db, FTAG);
1424 }
1425 
1426 boolean_t
1427 dmu_objset_userspace_present(objset_t *os)
1428 {
1429 	return (os->os_phys->os_flags &
1430 	    OBJSET_FLAG_USERACCOUNTING_COMPLETE);
1431 }
1432 
1433 int
1434 dmu_objset_userspace_upgrade(objset_t *os)
1435 {
1436 	uint64_t obj;
1437 	int err = 0;
1438 
1439 	if (dmu_objset_userspace_present(os))
1440 		return (0);
1441 	if (!dmu_objset_userused_enabled(os))
1442 		return (SET_ERROR(ENOTSUP));
1443 	if (dmu_objset_is_snapshot(os))
1444 		return (SET_ERROR(EINVAL));
1445 
1446 	/*
1447 	 * We simply need to mark every object dirty, so that it will be
1448 	 * synced out and now accounted.  If this is called
1449 	 * concurrently, or if we already did some work before crashing,
1450 	 * that's fine, since we track each object's accounted state
1451 	 * independently.
1452 	 */
1453 
1454 	for (obj = 0; err == 0; err = dmu_object_next(os, &obj, FALSE, 0)) {
1455 		dmu_tx_t *tx;
1456 		dmu_buf_t *db;
1457 		int objerr;
1458 
1459 		if (issig(JUSTLOOKING) && issig(FORREAL))
1460 			return (SET_ERROR(EINTR));
1461 
1462 		objerr = dmu_bonus_hold(os, obj, FTAG, &db);
1463 		if (objerr != 0)
1464 			continue;
1465 		tx = dmu_tx_create(os);
1466 		dmu_tx_hold_bonus(tx, obj);
1467 		objerr = dmu_tx_assign(tx, TXG_WAIT);
1468 		if (objerr != 0) {
1469 			dmu_tx_abort(tx);
1470 			continue;
1471 		}
1472 		dmu_buf_will_dirty(db, tx);
1473 		dmu_buf_rele(db, FTAG);
1474 		dmu_tx_commit(tx);
1475 	}
1476 
1477 	os->os_flags |= OBJSET_FLAG_USERACCOUNTING_COMPLETE;
1478 	txg_wait_synced(dmu_objset_pool(os), 0);
1479 	return (0);
1480 }
1481 
1482 void
1483 dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
1484     uint64_t *usedobjsp, uint64_t *availobjsp)
1485 {
1486 	dsl_dataset_space(os->os_dsl_dataset, refdbytesp, availbytesp,
1487 	    usedobjsp, availobjsp);
1488 }
1489 
1490 uint64_t
1491 dmu_objset_fsid_guid(objset_t *os)
1492 {
1493 	return (dsl_dataset_fsid_guid(os->os_dsl_dataset));
1494 }
1495 
1496 void
1497 dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat)
1498 {
1499 	stat->dds_type = os->os_phys->os_type;
1500 	if (os->os_dsl_dataset)
1501 		dsl_dataset_fast_stat(os->os_dsl_dataset, stat);
1502 }
1503 
1504 void
1505 dmu_objset_stats(objset_t *os, nvlist_t *nv)
1506 {
1507 	ASSERT(os->os_dsl_dataset ||
1508 	    os->os_phys->os_type == DMU_OST_META);
1509 
1510 	if (os->os_dsl_dataset != NULL)
1511 		dsl_dataset_stats(os->os_dsl_dataset, nv);
1512 
1513 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_TYPE,
1514 	    os->os_phys->os_type);
1515 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USERACCOUNTING,
1516 	    dmu_objset_userspace_present(os));
1517 }
1518 
1519 int
1520 dmu_objset_is_snapshot(objset_t *os)
1521 {
1522 	if (os->os_dsl_dataset != NULL)
1523 		return (os->os_dsl_dataset->ds_is_snapshot);
1524 	else
1525 		return (B_FALSE);
1526 }
1527 
1528 int
1529 dmu_snapshot_realname(objset_t *os, char *name, char *real, int maxlen,
1530     boolean_t *conflict)
1531 {
1532 	dsl_dataset_t *ds = os->os_dsl_dataset;
1533 	uint64_t ignored;
1534 
1535 	if (dsl_dataset_phys(ds)->ds_snapnames_zapobj == 0)
1536 		return (SET_ERROR(ENOENT));
1537 
1538 	return (zap_lookup_norm(ds->ds_dir->dd_pool->dp_meta_objset,
1539 	    dsl_dataset_phys(ds)->ds_snapnames_zapobj, name, 8, 1, &ignored,
1540 	    MT_FIRST, real, maxlen, conflict));
1541 }
1542 
1543 int
1544 dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
1545     uint64_t *idp, uint64_t *offp, boolean_t *case_conflict)
1546 {
1547 	dsl_dataset_t *ds = os->os_dsl_dataset;
1548 	zap_cursor_t cursor;
1549 	zap_attribute_t attr;
1550 
1551 	ASSERT(dsl_pool_config_held(dmu_objset_pool(os)));
1552 
1553 	if (dsl_dataset_phys(ds)->ds_snapnames_zapobj == 0)
1554 		return (SET_ERROR(ENOENT));
1555 
1556 	zap_cursor_init_serialized(&cursor,
1557 	    ds->ds_dir->dd_pool->dp_meta_objset,
1558 	    dsl_dataset_phys(ds)->ds_snapnames_zapobj, *offp);
1559 
1560 	if (zap_cursor_retrieve(&cursor, &attr) != 0) {
1561 		zap_cursor_fini(&cursor);
1562 		return (SET_ERROR(ENOENT));
1563 	}
1564 
1565 	if (strlen(attr.za_name) + 1 > namelen) {
1566 		zap_cursor_fini(&cursor);
1567 		return (SET_ERROR(ENAMETOOLONG));
1568 	}
1569 
1570 	(void) strcpy(name, attr.za_name);
1571 	if (idp)
1572 		*idp = attr.za_first_integer;
1573 	if (case_conflict)
1574 		*case_conflict = attr.za_normalization_conflict;
1575 	zap_cursor_advance(&cursor);
1576 	*offp = zap_cursor_serialize(&cursor);
1577 	zap_cursor_fini(&cursor);
1578 
1579 	return (0);
1580 }
1581 
1582 int
1583 dmu_dir_list_next(objset_t *os, int namelen, char *name,
1584     uint64_t *idp, uint64_t *offp)
1585 {
1586 	dsl_dir_t *dd = os->os_dsl_dataset->ds_dir;
1587 	zap_cursor_t cursor;
1588 	zap_attribute_t attr;
1589 
1590 	/* there is no next dir on a snapshot! */
1591 	if (os->os_dsl_dataset->ds_object !=
1592 	    dsl_dir_phys(dd)->dd_head_dataset_obj)
1593 		return (SET_ERROR(ENOENT));
1594 
1595 	zap_cursor_init_serialized(&cursor,
1596 	    dd->dd_pool->dp_meta_objset,
1597 	    dsl_dir_phys(dd)->dd_child_dir_zapobj, *offp);
1598 
1599 	if (zap_cursor_retrieve(&cursor, &attr) != 0) {
1600 		zap_cursor_fini(&cursor);
1601 		return (SET_ERROR(ENOENT));
1602 	}
1603 
1604 	if (strlen(attr.za_name) + 1 > namelen) {
1605 		zap_cursor_fini(&cursor);
1606 		return (SET_ERROR(ENAMETOOLONG));
1607 	}
1608 
1609 	(void) strcpy(name, attr.za_name);
1610 	if (idp)
1611 		*idp = attr.za_first_integer;
1612 	zap_cursor_advance(&cursor);
1613 	*offp = zap_cursor_serialize(&cursor);
1614 	zap_cursor_fini(&cursor);
1615 
1616 	return (0);
1617 }
1618 
1619 typedef struct dmu_objset_find_ctx {
1620 	taskq_t		*dc_tq;
1621 	dsl_pool_t	*dc_dp;
1622 	uint64_t	dc_ddobj;
1623 	int		(*dc_func)(dsl_pool_t *, dsl_dataset_t *, void *);
1624 	void		*dc_arg;
1625 	int		dc_flags;
1626 	kmutex_t	*dc_error_lock;
1627 	int		*dc_error;
1628 } dmu_objset_find_ctx_t;
1629 
1630 static void
1631 dmu_objset_find_dp_impl(dmu_objset_find_ctx_t *dcp)
1632 {
1633 	dsl_pool_t *dp = dcp->dc_dp;
1634 	dmu_objset_find_ctx_t *child_dcp;
1635 	dsl_dir_t *dd;
1636 	dsl_dataset_t *ds;
1637 	zap_cursor_t zc;
1638 	zap_attribute_t *attr;
1639 	uint64_t thisobj;
1640 	int err = 0;
1641 
1642 	/* don't process if there already was an error */
1643 	if (*dcp->dc_error != 0)
1644 		goto out;
1645 
1646 	err = dsl_dir_hold_obj(dp, dcp->dc_ddobj, NULL, FTAG, &dd);
1647 	if (err != 0)
1648 		goto out;
1649 
1650 	/* Don't visit hidden ($MOS & $ORIGIN) objsets. */
1651 	if (dd->dd_myname[0] == '$') {
1652 		dsl_dir_rele(dd, FTAG);
1653 		goto out;
1654 	}
1655 
1656 	thisobj = dsl_dir_phys(dd)->dd_head_dataset_obj;
1657 	attr = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
1658 
1659 	/*
1660 	 * Iterate over all children.
1661 	 */
1662 	if (dcp->dc_flags & DS_FIND_CHILDREN) {
1663 		for (zap_cursor_init(&zc, dp->dp_meta_objset,
1664 		    dsl_dir_phys(dd)->dd_child_dir_zapobj);
1665 		    zap_cursor_retrieve(&zc, attr) == 0;
1666 		    (void) zap_cursor_advance(&zc)) {
1667 			ASSERT3U(attr->za_integer_length, ==,
1668 			    sizeof (uint64_t));
1669 			ASSERT3U(attr->za_num_integers, ==, 1);
1670 
1671 			child_dcp = kmem_alloc(sizeof (*child_dcp), KM_SLEEP);
1672 			*child_dcp = *dcp;
1673 			child_dcp->dc_ddobj = attr->za_first_integer;
1674 			if (dcp->dc_tq != NULL)
1675 				(void) taskq_dispatch(dcp->dc_tq,
1676 				    dmu_objset_find_dp_cb, child_dcp, TQ_SLEEP);
1677 			else
1678 				dmu_objset_find_dp_impl(child_dcp);
1679 		}
1680 		zap_cursor_fini(&zc);
1681 	}
1682 
1683 	/*
1684 	 * Iterate over all snapshots.
1685 	 */
1686 	if (dcp->dc_flags & DS_FIND_SNAPSHOTS) {
1687 		dsl_dataset_t *ds;
1688 		err = dsl_dataset_hold_obj(dp, thisobj, FTAG, &ds);
1689 
1690 		if (err == 0) {
1691 			uint64_t snapobj;
1692 
1693 			snapobj = dsl_dataset_phys(ds)->ds_snapnames_zapobj;
1694 			dsl_dataset_rele(ds, FTAG);
1695 
1696 			for (zap_cursor_init(&zc, dp->dp_meta_objset, snapobj);
1697 			    zap_cursor_retrieve(&zc, attr) == 0;
1698 			    (void) zap_cursor_advance(&zc)) {
1699 				ASSERT3U(attr->za_integer_length, ==,
1700 				    sizeof (uint64_t));
1701 				ASSERT3U(attr->za_num_integers, ==, 1);
1702 
1703 				err = dsl_dataset_hold_obj(dp,
1704 				    attr->za_first_integer, FTAG, &ds);
1705 				if (err != 0)
1706 					break;
1707 				err = dcp->dc_func(dp, ds, dcp->dc_arg);
1708 				dsl_dataset_rele(ds, FTAG);
1709 				if (err != 0)
1710 					break;
1711 			}
1712 			zap_cursor_fini(&zc);
1713 		}
1714 	}
1715 
1716 	dsl_dir_rele(dd, FTAG);
1717 	kmem_free(attr, sizeof (zap_attribute_t));
1718 
1719 	if (err != 0)
1720 		goto out;
1721 
1722 	/*
1723 	 * Apply to self.
1724 	 */
1725 	err = dsl_dataset_hold_obj(dp, thisobj, FTAG, &ds);
1726 	if (err != 0)
1727 		goto out;
1728 	err = dcp->dc_func(dp, ds, dcp->dc_arg);
1729 	dsl_dataset_rele(ds, FTAG);
1730 
1731 out:
1732 	if (err != 0) {
1733 		mutex_enter(dcp->dc_error_lock);
1734 		/* only keep first error */
1735 		if (*dcp->dc_error == 0)
1736 			*dcp->dc_error = err;
1737 		mutex_exit(dcp->dc_error_lock);
1738 	}
1739 
1740 	kmem_free(dcp, sizeof (*dcp));
1741 }
1742 
1743 static void
1744 dmu_objset_find_dp_cb(void *arg)
1745 {
1746 	dmu_objset_find_ctx_t *dcp = arg;
1747 	dsl_pool_t *dp = dcp->dc_dp;
1748 
1749 	/*
1750 	 * We need to get a pool_config_lock here, as there are several
1751 	 * asssert(pool_config_held) down the stack. Getting a lock via
1752 	 * dsl_pool_config_enter is risky, as it might be stalled by a
1753 	 * pending writer. This would deadlock, as the write lock can
1754 	 * only be granted when our parent thread gives up the lock.
1755 	 * The _prio interface gives us priority over a pending writer.
1756 	 */
1757 	dsl_pool_config_enter_prio(dp, FTAG);
1758 
1759 	dmu_objset_find_dp_impl(dcp);
1760 
1761 	dsl_pool_config_exit(dp, FTAG);
1762 }
1763 
1764 /*
1765  * Find objsets under and including ddobj, call func(ds) on each.
1766  * The order for the enumeration is completely undefined.
1767  * func is called with dsl_pool_config held.
1768  */
1769 int
1770 dmu_objset_find_dp(dsl_pool_t *dp, uint64_t ddobj,
1771     int func(dsl_pool_t *, dsl_dataset_t *, void *), void *arg, int flags)
1772 {
1773 	int error = 0;
1774 	taskq_t *tq = NULL;
1775 	int ntasks;
1776 	dmu_objset_find_ctx_t *dcp;
1777 	kmutex_t err_lock;
1778 
1779 	mutex_init(&err_lock, NULL, MUTEX_DEFAULT, NULL);
1780 	dcp = kmem_alloc(sizeof (*dcp), KM_SLEEP);
1781 	dcp->dc_tq = NULL;
1782 	dcp->dc_dp = dp;
1783 	dcp->dc_ddobj = ddobj;
1784 	dcp->dc_func = func;
1785 	dcp->dc_arg = arg;
1786 	dcp->dc_flags = flags;
1787 	dcp->dc_error_lock = &err_lock;
1788 	dcp->dc_error = &error;
1789 
1790 	if ((flags & DS_FIND_SERIALIZE) || dsl_pool_config_held_writer(dp)) {
1791 		/*
1792 		 * In case a write lock is held we can't make use of
1793 		 * parallelism, as down the stack of the worker threads
1794 		 * the lock is asserted via dsl_pool_config_held.
1795 		 * In case of a read lock this is solved by getting a read
1796 		 * lock in each worker thread, which isn't possible in case
1797 		 * of a writer lock. So we fall back to the synchronous path
1798 		 * here.
1799 		 * In the future it might be possible to get some magic into
1800 		 * dsl_pool_config_held in a way that it returns true for
1801 		 * the worker threads so that a single lock held from this
1802 		 * thread suffices. For now, stay single threaded.
1803 		 */
1804 		dmu_objset_find_dp_impl(dcp);
1805 
1806 		return (error);
1807 	}
1808 
1809 	ntasks = dmu_find_threads;
1810 	if (ntasks == 0)
1811 		ntasks = vdev_count_leaves(dp->dp_spa) * 4;
1812 	tq = taskq_create("dmu_objset_find", ntasks, minclsyspri, ntasks,
1813 	    INT_MAX, 0);
1814 	if (tq == NULL) {
1815 		kmem_free(dcp, sizeof (*dcp));
1816 		return (SET_ERROR(ENOMEM));
1817 	}
1818 	dcp->dc_tq = tq;
1819 
1820 	/* dcp will be freed by task */
1821 	(void) taskq_dispatch(tq, dmu_objset_find_dp_cb, dcp, TQ_SLEEP);
1822 
1823 	/*
1824 	 * PORTING: this code relies on the property of taskq_wait to wait
1825 	 * until no more tasks are queued and no more tasks are active. As
1826 	 * we always queue new tasks from within other tasks, task_wait
1827 	 * reliably waits for the full recursion to finish, even though we
1828 	 * enqueue new tasks after taskq_wait has been called.
1829 	 * On platforms other than illumos, taskq_wait may not have this
1830 	 * property.
1831 	 */
1832 	taskq_wait(tq);
1833 	taskq_destroy(tq);
1834 	mutex_destroy(&err_lock);
1835 
1836 	return (error);
1837 }
1838 
1839 /*
1840  * Find all objsets under name, and for each, call 'func(child_name, arg)'.
1841  * The dp_config_rwlock must not be held when this is called, and it
1842  * will not be held when the callback is called.
1843  * Therefore this function should only be used when the pool is not changing
1844  * (e.g. in syncing context), or the callback can deal with the possible races.
1845  */
1846 static int
1847 dmu_objset_find_impl(spa_t *spa, const char *name,
1848     int func(const char *, void *), void *arg, int flags)
1849 {
1850 	dsl_dir_t *dd;
1851 	dsl_pool_t *dp = spa_get_dsl(spa);
1852 	dsl_dataset_t *ds;
1853 	zap_cursor_t zc;
1854 	zap_attribute_t *attr;
1855 	char *child;
1856 	uint64_t thisobj;
1857 	int err;
1858 
1859 	dsl_pool_config_enter(dp, FTAG);
1860 
1861 	err = dsl_dir_hold(dp, name, FTAG, &dd, NULL);
1862 	if (err != 0) {
1863 		dsl_pool_config_exit(dp, FTAG);
1864 		return (err);
1865 	}
1866 
1867 	/* Don't visit hidden ($MOS & $ORIGIN) objsets. */
1868 	if (dd->dd_myname[0] == '$') {
1869 		dsl_dir_rele(dd, FTAG);
1870 		dsl_pool_config_exit(dp, FTAG);
1871 		return (0);
1872 	}
1873 
1874 	thisobj = dsl_dir_phys(dd)->dd_head_dataset_obj;
1875 	attr = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
1876 
1877 	/*
1878 	 * Iterate over all children.
1879 	 */
1880 	if (flags & DS_FIND_CHILDREN) {
1881 		for (zap_cursor_init(&zc, dp->dp_meta_objset,
1882 		    dsl_dir_phys(dd)->dd_child_dir_zapobj);
1883 		    zap_cursor_retrieve(&zc, attr) == 0;
1884 		    (void) zap_cursor_advance(&zc)) {
1885 			ASSERT3U(attr->za_integer_length, ==,
1886 			    sizeof (uint64_t));
1887 			ASSERT3U(attr->za_num_integers, ==, 1);
1888 
1889 			child = kmem_asprintf("%s/%s", name, attr->za_name);
1890 			dsl_pool_config_exit(dp, FTAG);
1891 			err = dmu_objset_find_impl(spa, child,
1892 			    func, arg, flags);
1893 			dsl_pool_config_enter(dp, FTAG);
1894 			strfree(child);
1895 			if (err != 0)
1896 				break;
1897 		}
1898 		zap_cursor_fini(&zc);
1899 
1900 		if (err != 0) {
1901 			dsl_dir_rele(dd, FTAG);
1902 			dsl_pool_config_exit(dp, FTAG);
1903 			kmem_free(attr, sizeof (zap_attribute_t));
1904 			return (err);
1905 		}
1906 	}
1907 
1908 	/*
1909 	 * Iterate over all snapshots.
1910 	 */
1911 	if (flags & DS_FIND_SNAPSHOTS) {
1912 		err = dsl_dataset_hold_obj(dp, thisobj, FTAG, &ds);
1913 
1914 		if (err == 0) {
1915 			uint64_t snapobj;
1916 
1917 			snapobj = dsl_dataset_phys(ds)->ds_snapnames_zapobj;
1918 			dsl_dataset_rele(ds, FTAG);
1919 
1920 			for (zap_cursor_init(&zc, dp->dp_meta_objset, snapobj);
1921 			    zap_cursor_retrieve(&zc, attr) == 0;
1922 			    (void) zap_cursor_advance(&zc)) {
1923 				ASSERT3U(attr->za_integer_length, ==,
1924 				    sizeof (uint64_t));
1925 				ASSERT3U(attr->za_num_integers, ==, 1);
1926 
1927 				child = kmem_asprintf("%s@%s",
1928 				    name, attr->za_name);
1929 				dsl_pool_config_exit(dp, FTAG);
1930 				err = func(child, arg);
1931 				dsl_pool_config_enter(dp, FTAG);
1932 				strfree(child);
1933 				if (err != 0)
1934 					break;
1935 			}
1936 			zap_cursor_fini(&zc);
1937 		}
1938 	}
1939 
1940 	dsl_dir_rele(dd, FTAG);
1941 	kmem_free(attr, sizeof (zap_attribute_t));
1942 	dsl_pool_config_exit(dp, FTAG);
1943 
1944 	if (err != 0)
1945 		return (err);
1946 
1947 	/* Apply to self. */
1948 	return (func(name, arg));
1949 }
1950 
1951 /*
1952  * See comment above dmu_objset_find_impl().
1953  */
1954 int
1955 dmu_objset_find(char *name, int func(const char *, void *), void *arg,
1956     int flags)
1957 {
1958 	spa_t *spa;
1959 	int error;
1960 
1961 	error = spa_open(name, &spa, FTAG);
1962 	if (error != 0)
1963 		return (error);
1964 	error = dmu_objset_find_impl(spa, name, func, arg, flags);
1965 	spa_close(spa, FTAG);
1966 	return (error);
1967 }
1968 
1969 void
1970 dmu_objset_set_user(objset_t *os, void *user_ptr)
1971 {
1972 	ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
1973 	os->os_user_ptr = user_ptr;
1974 }
1975 
1976 void *
1977 dmu_objset_get_user(objset_t *os)
1978 {
1979 	ASSERT(MUTEX_HELD(&os->os_user_ptr_lock));
1980 	return (os->os_user_ptr);
1981 }
1982 
1983 /*
1984  * Determine name of filesystem, given name of snapshot.
1985  * buf must be at least MAXNAMELEN bytes
1986  */
1987 int
1988 dmu_fsname(const char *snapname, char *buf)
1989 {
1990 	char *atp = strchr(snapname, '@');
1991 	if (atp == NULL)
1992 		return (SET_ERROR(EINVAL));
1993 	if (atp - snapname >= MAXNAMELEN)
1994 		return (SET_ERROR(ENAMETOOLONG));
1995 	(void) strlcpy(buf, snapname, atp - snapname + 1);
1996 	return (0);
1997 }
1998