xref: /titanic_41/usr/src/uts/common/fs/zfs/dsl_pool.c (revision 8f72ee6d994ea9ab828d444a1aa43fdedfeedc2a)
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) 2011, 2014 by Delphix. All rights reserved.
24  * Copyright (c) 2013 Steven Hartland. All rights reserved.
25  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
26  */
27 
28 #include <sys/dsl_pool.h>
29 #include <sys/dsl_dataset.h>
30 #include <sys/dsl_prop.h>
31 #include <sys/dsl_dir.h>
32 #include <sys/dsl_synctask.h>
33 #include <sys/dsl_scan.h>
34 #include <sys/dnode.h>
35 #include <sys/dmu_tx.h>
36 #include <sys/dmu_objset.h>
37 #include <sys/arc.h>
38 #include <sys/zap.h>
39 #include <sys/zio.h>
40 #include <sys/zfs_context.h>
41 #include <sys/fs/zfs.h>
42 #include <sys/zfs_znode.h>
43 #include <sys/spa_impl.h>
44 #include <sys/dsl_deadlist.h>
45 #include <sys/bptree.h>
46 #include <sys/zfeature.h>
47 #include <sys/zil_impl.h>
48 #include <sys/dsl_userhold.h>
49 
50 /*
51  * ZFS Write Throttle
52  * ------------------
53  *
54  * ZFS must limit the rate of incoming writes to the rate at which it is able
55  * to sync data modifications to the backend storage. Throttling by too much
56  * creates an artificial limit; throttling by too little can only be sustained
57  * for short periods and would lead to highly lumpy performance. On a per-pool
58  * basis, ZFS tracks the amount of modified (dirty) data. As operations change
59  * data, the amount of dirty data increases; as ZFS syncs out data, the amount
60  * of dirty data decreases. When the amount of dirty data exceeds a
61  * predetermined threshold further modifications are blocked until the amount
62  * of dirty data decreases (as data is synced out).
63  *
64  * The limit on dirty data is tunable, and should be adjusted according to
65  * both the IO capacity and available memory of the system. The larger the
66  * window, the more ZFS is able to aggregate and amortize metadata (and data)
67  * changes. However, memory is a limited resource, and allowing for more dirty
68  * data comes at the cost of keeping other useful data in memory (for example
69  * ZFS data cached by the ARC).
70  *
71  * Implementation
72  *
73  * As buffers are modified dsl_pool_willuse_space() increments both the per-
74  * txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
75  * dirty space used; dsl_pool_dirty_space() decrements those values as data
76  * is synced out from dsl_pool_sync(). While only the poolwide value is
77  * relevant, the per-txg value is useful for debugging. The tunable
78  * zfs_dirty_data_max determines the dirty space limit. Once that value is
79  * exceeded, new writes are halted until space frees up.
80  *
81  * The zfs_dirty_data_sync tunable dictates the threshold at which we
82  * ensure that there is a txg syncing (see the comment in txg.c for a full
83  * description of transaction group stages).
84  *
85  * The IO scheduler uses both the dirty space limit and current amount of
86  * dirty data as inputs. Those values affect the number of concurrent IOs ZFS
87  * issues. See the comment in vdev_queue.c for details of the IO scheduler.
88  *
89  * The delay is also calculated based on the amount of dirty data.  See the
90  * comment above dmu_tx_delay() for details.
91  */
92 
93 /*
94  * zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
95  * capped at zfs_dirty_data_max_max.  It can also be overridden in /etc/system.
96  */
97 uint64_t zfs_dirty_data_max;
98 uint64_t zfs_dirty_data_max_max = 4ULL * 1024 * 1024 * 1024;
99 int zfs_dirty_data_max_percent = 10;
100 
101 /*
102  * If there is at least this much dirty data, push out a txg.
103  */
104 uint64_t zfs_dirty_data_sync = 64 * 1024 * 1024;
105 
106 /*
107  * Once there is this amount of dirty data, the dmu_tx_delay() will kick in
108  * and delay each transaction.
109  * This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
110  */
111 int zfs_delay_min_dirty_percent = 60;
112 
113 /*
114  * This controls how quickly the delay approaches infinity.
115  * Larger values cause it to delay more for a given amount of dirty data.
116  * Therefore larger values will cause there to be less dirty data for a
117  * given throughput.
118  *
119  * For the smoothest delay, this value should be about 1 billion divided
120  * by the maximum number of operations per second.  This will smoothly
121  * handle between 10x and 1/10th this number.
122  *
123  * Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
124  * multiply in dmu_tx_delay().
125  */
126 uint64_t zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
127 
128 
129 hrtime_t zfs_throttle_delay = MSEC2NSEC(10);
130 hrtime_t zfs_throttle_resolution = MSEC2NSEC(10);
131 
132 int
dsl_pool_open_special_dir(dsl_pool_t * dp,const char * name,dsl_dir_t ** ddp)133 dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
134 {
135 	uint64_t obj;
136 	int err;
137 
138 	err = zap_lookup(dp->dp_meta_objset,
139 	    dsl_dir_phys(dp->dp_root_dir)->dd_child_dir_zapobj,
140 	    name, sizeof (obj), 1, &obj);
141 	if (err)
142 		return (err);
143 
144 	return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
145 }
146 
147 static dsl_pool_t *
dsl_pool_open_impl(spa_t * spa,uint64_t txg)148 dsl_pool_open_impl(spa_t *spa, uint64_t txg)
149 {
150 	dsl_pool_t *dp;
151 	blkptr_t *bp = spa_get_rootblkptr(spa);
152 
153 	dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
154 	dp->dp_spa = spa;
155 	dp->dp_meta_rootbp = *bp;
156 	rrw_init(&dp->dp_config_rwlock, B_TRUE);
157 	txg_init(dp, txg);
158 
159 	txg_list_create(&dp->dp_dirty_datasets,
160 	    offsetof(dsl_dataset_t, ds_dirty_link));
161 	txg_list_create(&dp->dp_dirty_zilogs,
162 	    offsetof(zilog_t, zl_dirty_link));
163 	txg_list_create(&dp->dp_dirty_dirs,
164 	    offsetof(dsl_dir_t, dd_dirty_link));
165 	txg_list_create(&dp->dp_sync_tasks,
166 	    offsetof(dsl_sync_task_t, dst_node));
167 
168 	mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
169 	cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
170 
171 	dp->dp_vnrele_taskq = taskq_create("zfs_vn_rele_taskq", 1, minclsyspri,
172 	    1, 4, 0);
173 
174 	return (dp);
175 }
176 
177 int
dsl_pool_init(spa_t * spa,uint64_t txg,dsl_pool_t ** dpp)178 dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
179 {
180 	int err;
181 	dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
182 
183 	err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
184 	    &dp->dp_meta_objset);
185 	if (err != 0)
186 		dsl_pool_close(dp);
187 	else
188 		*dpp = dp;
189 
190 	return (err);
191 }
192 
193 int
dsl_pool_open(dsl_pool_t * dp)194 dsl_pool_open(dsl_pool_t *dp)
195 {
196 	int err;
197 	dsl_dir_t *dd;
198 	dsl_dataset_t *ds;
199 	uint64_t obj;
200 
201 	rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
202 	err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
203 	    DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1,
204 	    &dp->dp_root_dir_obj);
205 	if (err)
206 		goto out;
207 
208 	err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
209 	    NULL, dp, &dp->dp_root_dir);
210 	if (err)
211 		goto out;
212 
213 	err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir);
214 	if (err)
215 		goto out;
216 
217 	if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
218 		err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
219 		if (err)
220 			goto out;
221 		err = dsl_dataset_hold_obj(dp,
222 		    dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds);
223 		if (err == 0) {
224 			err = dsl_dataset_hold_obj(dp,
225 			    dsl_dataset_phys(ds)->ds_prev_snap_obj, dp,
226 			    &dp->dp_origin_snap);
227 			dsl_dataset_rele(ds, FTAG);
228 		}
229 		dsl_dir_rele(dd, dp);
230 		if (err)
231 			goto out;
232 	}
233 
234 	if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
235 		err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
236 		    &dp->dp_free_dir);
237 		if (err)
238 			goto out;
239 
240 		err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
241 		    DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
242 		if (err)
243 			goto out;
244 		VERIFY0(bpobj_open(&dp->dp_free_bpobj,
245 		    dp->dp_meta_objset, obj));
246 	}
247 
248 	/*
249 	 * Note: errors ignored, because the leak dir will not exist if we
250 	 * have not encountered a leak yet.
251 	 */
252 	(void) dsl_pool_open_special_dir(dp, LEAK_DIR_NAME,
253 	    &dp->dp_leak_dir);
254 
255 	if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
256 		err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
257 		    DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
258 		    &dp->dp_bptree_obj);
259 		if (err != 0)
260 			goto out;
261 	}
262 
263 	if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_EMPTY_BPOBJ)) {
264 		err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
265 		    DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
266 		    &dp->dp_empty_bpobj);
267 		if (err != 0)
268 			goto out;
269 	}
270 
271 	err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
272 	    DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
273 	    &dp->dp_tmp_userrefs_obj);
274 	if (err == ENOENT)
275 		err = 0;
276 	if (err)
277 		goto out;
278 
279 	err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
280 
281 out:
282 	rrw_exit(&dp->dp_config_rwlock, FTAG);
283 	return (err);
284 }
285 
286 void
dsl_pool_close(dsl_pool_t * dp)287 dsl_pool_close(dsl_pool_t *dp)
288 {
289 	/*
290 	 * Drop our references from dsl_pool_open().
291 	 *
292 	 * Since we held the origin_snap from "syncing" context (which
293 	 * includes pool-opening context), it actually only got a "ref"
294 	 * and not a hold, so just drop that here.
295 	 */
296 	if (dp->dp_origin_snap)
297 		dsl_dataset_rele(dp->dp_origin_snap, dp);
298 	if (dp->dp_mos_dir)
299 		dsl_dir_rele(dp->dp_mos_dir, dp);
300 	if (dp->dp_free_dir)
301 		dsl_dir_rele(dp->dp_free_dir, dp);
302 	if (dp->dp_leak_dir)
303 		dsl_dir_rele(dp->dp_leak_dir, dp);
304 	if (dp->dp_root_dir)
305 		dsl_dir_rele(dp->dp_root_dir, dp);
306 
307 	bpobj_close(&dp->dp_free_bpobj);
308 
309 	/* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
310 	if (dp->dp_meta_objset)
311 		dmu_objset_evict(dp->dp_meta_objset);
312 
313 	txg_list_destroy(&dp->dp_dirty_datasets);
314 	txg_list_destroy(&dp->dp_dirty_zilogs);
315 	txg_list_destroy(&dp->dp_sync_tasks);
316 	txg_list_destroy(&dp->dp_dirty_dirs);
317 
318 	/*
319 	 * We can't set retry to TRUE since we're explicitly specifying
320 	 * a spa to flush. This is good enough; any missed buffers for
321 	 * this spa won't cause trouble, and they'll eventually fall
322 	 * out of the ARC just like any other unused buffer.
323 	 */
324 	arc_flush(dp->dp_spa, FALSE);
325 
326 	txg_fini(dp);
327 	dsl_scan_fini(dp);
328 	dmu_buf_user_evict_wait();
329 
330 	rrw_destroy(&dp->dp_config_rwlock);
331 	mutex_destroy(&dp->dp_lock);
332 	taskq_destroy(dp->dp_vnrele_taskq);
333 	if (dp->dp_blkstats)
334 		kmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
335 	kmem_free(dp, sizeof (dsl_pool_t));
336 }
337 
338 dsl_pool_t *
dsl_pool_create(spa_t * spa,nvlist_t * zplprops,uint64_t txg)339 dsl_pool_create(spa_t *spa, nvlist_t *zplprops, uint64_t txg)
340 {
341 	int err;
342 	dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
343 	dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
344 	objset_t *os;
345 	dsl_dataset_t *ds;
346 	uint64_t obj;
347 
348 	rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
349 
350 	/* create and open the MOS (meta-objset) */
351 	dp->dp_meta_objset = dmu_objset_create_impl(spa,
352 	    NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
353 
354 	/* create the pool directory */
355 	err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
356 	    DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
357 	ASSERT0(err);
358 
359 	/* Initialize scan structures */
360 	VERIFY0(dsl_scan_init(dp, txg));
361 
362 	/* create and open the root dir */
363 	dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
364 	VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
365 	    NULL, dp, &dp->dp_root_dir));
366 
367 	/* create and open the meta-objset dir */
368 	(void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
369 	VERIFY0(dsl_pool_open_special_dir(dp,
370 	    MOS_DIR_NAME, &dp->dp_mos_dir));
371 
372 	if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
373 		/* create and open the free dir */
374 		(void) dsl_dir_create_sync(dp, dp->dp_root_dir,
375 		    FREE_DIR_NAME, tx);
376 		VERIFY0(dsl_pool_open_special_dir(dp,
377 		    FREE_DIR_NAME, &dp->dp_free_dir));
378 
379 		/* create and open the free_bplist */
380 		obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
381 		VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
382 		    DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
383 		VERIFY0(bpobj_open(&dp->dp_free_bpobj,
384 		    dp->dp_meta_objset, obj));
385 	}
386 
387 	if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
388 		dsl_pool_create_origin(dp, tx);
389 
390 	/* create the root dataset */
391 	obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, 0, tx);
392 
393 	/* create the root objset */
394 	VERIFY0(dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
395 	os = dmu_objset_create_impl(dp->dp_spa, ds,
396 	    dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
397 #ifdef _KERNEL
398 	zfs_create_fs(os, kcred, zplprops, tx);
399 #endif
400 	dsl_dataset_rele(ds, FTAG);
401 
402 	dmu_tx_commit(tx);
403 
404 	rrw_exit(&dp->dp_config_rwlock, FTAG);
405 
406 	return (dp);
407 }
408 
409 /*
410  * Account for the meta-objset space in its placeholder dsl_dir.
411  */
412 void
dsl_pool_mos_diduse_space(dsl_pool_t * dp,int64_t used,int64_t comp,int64_t uncomp)413 dsl_pool_mos_diduse_space(dsl_pool_t *dp,
414     int64_t used, int64_t comp, int64_t uncomp)
415 {
416 	ASSERT3U(comp, ==, uncomp); /* it's all metadata */
417 	mutex_enter(&dp->dp_lock);
418 	dp->dp_mos_used_delta += used;
419 	dp->dp_mos_compressed_delta += comp;
420 	dp->dp_mos_uncompressed_delta += uncomp;
421 	mutex_exit(&dp->dp_lock);
422 }
423 
424 static int
deadlist_enqueue_cb(void * arg,const blkptr_t * bp,dmu_tx_t * tx)425 deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
426 {
427 	dsl_deadlist_t *dl = arg;
428 	dsl_deadlist_insert(dl, bp, tx);
429 	return (0);
430 }
431 
432 static void
dsl_pool_sync_mos(dsl_pool_t * dp,dmu_tx_t * tx)433 dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
434 {
435 	zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
436 	dmu_objset_sync(dp->dp_meta_objset, zio, tx);
437 	VERIFY0(zio_wait(zio));
438 	dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
439 	spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
440 }
441 
442 static void
dsl_pool_dirty_delta(dsl_pool_t * dp,int64_t delta)443 dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
444 {
445 	ASSERT(MUTEX_HELD(&dp->dp_lock));
446 
447 	if (delta < 0)
448 		ASSERT3U(-delta, <=, dp->dp_dirty_total);
449 
450 	dp->dp_dirty_total += delta;
451 
452 	/*
453 	 * Note: we signal even when increasing dp_dirty_total.
454 	 * This ensures forward progress -- each thread wakes the next waiter.
455 	 */
456 	if (dp->dp_dirty_total <= zfs_dirty_data_max)
457 		cv_signal(&dp->dp_spaceavail_cv);
458 }
459 
460 void
dsl_pool_sync(dsl_pool_t * dp,uint64_t txg)461 dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
462 {
463 	zio_t *zio;
464 	dmu_tx_t *tx;
465 	dsl_dir_t *dd;
466 	dsl_dataset_t *ds;
467 	objset_t *mos = dp->dp_meta_objset;
468 	list_t synced_datasets;
469 
470 	list_create(&synced_datasets, sizeof (dsl_dataset_t),
471 	    offsetof(dsl_dataset_t, ds_synced_link));
472 
473 	tx = dmu_tx_create_assigned(dp, txg);
474 
475 	/*
476 	 * Write out all dirty blocks of dirty datasets.
477 	 */
478 	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
479 	while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
480 		/*
481 		 * We must not sync any non-MOS datasets twice, because
482 		 * we may have taken a snapshot of them.  However, we
483 		 * may sync newly-created datasets on pass 2.
484 		 */
485 		ASSERT(!list_link_active(&ds->ds_synced_link));
486 		list_insert_tail(&synced_datasets, ds);
487 		dsl_dataset_sync(ds, zio, tx);
488 	}
489 	VERIFY0(zio_wait(zio));
490 
491 	/*
492 	 * We have written all of the accounted dirty data, so our
493 	 * dp_space_towrite should now be zero.  However, some seldom-used
494 	 * code paths do not adhere to this (e.g. dbuf_undirty(), also
495 	 * rounding error in dbuf_write_physdone).
496 	 * Shore up the accounting of any dirtied space now.
497 	 */
498 	dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
499 
500 	/*
501 	 * After the data blocks have been written (ensured by the zio_wait()
502 	 * above), update the user/group space accounting.
503 	 */
504 	for (ds = list_head(&synced_datasets); ds != NULL;
505 	    ds = list_next(&synced_datasets, ds)) {
506 		dmu_objset_do_userquota_updates(ds->ds_objset, tx);
507 	}
508 
509 	/*
510 	 * Sync the datasets again to push out the changes due to
511 	 * userspace updates.  This must be done before we process the
512 	 * sync tasks, so that any snapshots will have the correct
513 	 * user accounting information (and we won't get confused
514 	 * about which blocks are part of the snapshot).
515 	 */
516 	zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
517 	while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
518 		ASSERT(list_link_active(&ds->ds_synced_link));
519 		dmu_buf_rele(ds->ds_dbuf, ds);
520 		dsl_dataset_sync(ds, zio, tx);
521 	}
522 	VERIFY0(zio_wait(zio));
523 
524 	/*
525 	 * Now that the datasets have been completely synced, we can
526 	 * clean up our in-memory structures accumulated while syncing:
527 	 *
528 	 *  - move dead blocks from the pending deadlist to the on-disk deadlist
529 	 *  - release hold from dsl_dataset_dirty()
530 	 */
531 	while ((ds = list_remove_head(&synced_datasets)) != NULL) {
532 		objset_t *os = ds->ds_objset;
533 		bplist_iterate(&ds->ds_pending_deadlist,
534 		    deadlist_enqueue_cb, &ds->ds_deadlist, tx);
535 		ASSERT(!dmu_objset_is_dirty(os, txg));
536 		dmu_buf_rele(ds->ds_dbuf, ds);
537 	}
538 	while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
539 		dsl_dir_sync(dd, tx);
540 	}
541 
542 	/*
543 	 * The MOS's space is accounted for in the pool/$MOS
544 	 * (dp_mos_dir).  We can't modify the mos while we're syncing
545 	 * it, so we remember the deltas and apply them here.
546 	 */
547 	if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
548 	    dp->dp_mos_uncompressed_delta != 0) {
549 		dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
550 		    dp->dp_mos_used_delta,
551 		    dp->dp_mos_compressed_delta,
552 		    dp->dp_mos_uncompressed_delta, tx);
553 		dp->dp_mos_used_delta = 0;
554 		dp->dp_mos_compressed_delta = 0;
555 		dp->dp_mos_uncompressed_delta = 0;
556 	}
557 
558 	if (list_head(&mos->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
559 	    list_head(&mos->os_free_dnodes[txg & TXG_MASK]) != NULL) {
560 		dsl_pool_sync_mos(dp, tx);
561 	}
562 
563 	/*
564 	 * If we modify a dataset in the same txg that we want to destroy it,
565 	 * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
566 	 * dsl_dir_destroy_check() will fail if there are unexpected holds.
567 	 * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
568 	 * and clearing the hold on it) before we process the sync_tasks.
569 	 * The MOS data dirtied by the sync_tasks will be synced on the next
570 	 * pass.
571 	 */
572 	if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
573 		dsl_sync_task_t *dst;
574 		/*
575 		 * No more sync tasks should have been added while we
576 		 * were syncing.
577 		 */
578 		ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
579 		while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
580 			dsl_sync_task_sync(dst, tx);
581 	}
582 
583 	dmu_tx_commit(tx);
584 
585 	DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
586 }
587 
588 void
dsl_pool_sync_done(dsl_pool_t * dp,uint64_t txg)589 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
590 {
591 	zilog_t *zilog;
592 
593 	while (zilog = txg_list_remove(&dp->dp_dirty_zilogs, txg)) {
594 		dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
595 		zil_clean(zilog, txg);
596 		ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
597 		dmu_buf_rele(ds->ds_dbuf, zilog);
598 	}
599 	ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
600 }
601 
602 /*
603  * TRUE if the current thread is the tx_sync_thread or if we
604  * are being called from SPA context during pool initialization.
605  */
606 int
dsl_pool_sync_context(dsl_pool_t * dp)607 dsl_pool_sync_context(dsl_pool_t *dp)
608 {
609 	return (curthread == dp->dp_tx.tx_sync_thread ||
610 	    spa_is_initializing(dp->dp_spa));
611 }
612 
613 uint64_t
dsl_pool_adjustedsize(dsl_pool_t * dp,boolean_t netfree)614 dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
615 {
616 	uint64_t space, resv;
617 
618 	/*
619 	 * If we're trying to assess whether it's OK to do a free,
620 	 * cut the reservation in half to allow forward progress
621 	 * (e.g. make it possible to rm(1) files from a full pool).
622 	 */
623 	space = spa_get_dspace(dp->dp_spa);
624 	resv = spa_get_slop_space(dp->dp_spa);
625 	if (netfree)
626 		resv >>= 1;
627 
628 	return (space - resv);
629 }
630 
631 boolean_t
dsl_pool_need_dirty_delay(dsl_pool_t * dp)632 dsl_pool_need_dirty_delay(dsl_pool_t *dp)
633 {
634 	uint64_t delay_min_bytes =
635 	    zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
636 	boolean_t rv;
637 
638 	mutex_enter(&dp->dp_lock);
639 	if (dp->dp_dirty_total > zfs_dirty_data_sync)
640 		txg_kick(dp);
641 	rv = (dp->dp_dirty_total > delay_min_bytes);
642 	mutex_exit(&dp->dp_lock);
643 	return (rv);
644 }
645 
646 void
dsl_pool_dirty_space(dsl_pool_t * dp,int64_t space,dmu_tx_t * tx)647 dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
648 {
649 	if (space > 0) {
650 		mutex_enter(&dp->dp_lock);
651 		dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
652 		dsl_pool_dirty_delta(dp, space);
653 		mutex_exit(&dp->dp_lock);
654 	}
655 }
656 
657 void
dsl_pool_undirty_space(dsl_pool_t * dp,int64_t space,uint64_t txg)658 dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
659 {
660 	ASSERT3S(space, >=, 0);
661 	if (space == 0)
662 		return;
663 	mutex_enter(&dp->dp_lock);
664 	if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
665 		/* XXX writing something we didn't dirty? */
666 		space = dp->dp_dirty_pertxg[txg & TXG_MASK];
667 	}
668 	ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
669 	dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
670 	ASSERT3U(dp->dp_dirty_total, >=, space);
671 	dsl_pool_dirty_delta(dp, -space);
672 	mutex_exit(&dp->dp_lock);
673 }
674 
675 /* ARGSUSED */
676 static int
upgrade_clones_cb(dsl_pool_t * dp,dsl_dataset_t * hds,void * arg)677 upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
678 {
679 	dmu_tx_t *tx = arg;
680 	dsl_dataset_t *ds, *prev = NULL;
681 	int err;
682 
683 	err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
684 	if (err)
685 		return (err);
686 
687 	while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
688 		err = dsl_dataset_hold_obj(dp,
689 		    dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
690 		if (err) {
691 			dsl_dataset_rele(ds, FTAG);
692 			return (err);
693 		}
694 
695 		if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object)
696 			break;
697 		dsl_dataset_rele(ds, FTAG);
698 		ds = prev;
699 		prev = NULL;
700 	}
701 
702 	if (prev == NULL) {
703 		prev = dp->dp_origin_snap;
704 
705 		/*
706 		 * The $ORIGIN can't have any data, or the accounting
707 		 * will be wrong.
708 		 */
709 		ASSERT0(dsl_dataset_phys(prev)->ds_bp.blk_birth);
710 
711 		/* The origin doesn't get attached to itself */
712 		if (ds->ds_object == prev->ds_object) {
713 			dsl_dataset_rele(ds, FTAG);
714 			return (0);
715 		}
716 
717 		dmu_buf_will_dirty(ds->ds_dbuf, tx);
718 		dsl_dataset_phys(ds)->ds_prev_snap_obj = prev->ds_object;
719 		dsl_dataset_phys(ds)->ds_prev_snap_txg =
720 		    dsl_dataset_phys(prev)->ds_creation_txg;
721 
722 		dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
723 		dsl_dir_phys(ds->ds_dir)->dd_origin_obj = prev->ds_object;
724 
725 		dmu_buf_will_dirty(prev->ds_dbuf, tx);
726 		dsl_dataset_phys(prev)->ds_num_children++;
727 
728 		if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0) {
729 			ASSERT(ds->ds_prev == NULL);
730 			VERIFY0(dsl_dataset_hold_obj(dp,
731 			    dsl_dataset_phys(ds)->ds_prev_snap_obj,
732 			    ds, &ds->ds_prev));
733 		}
734 	}
735 
736 	ASSERT3U(dsl_dir_phys(ds->ds_dir)->dd_origin_obj, ==, prev->ds_object);
737 	ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_obj, ==, prev->ds_object);
738 
739 	if (dsl_dataset_phys(prev)->ds_next_clones_obj == 0) {
740 		dmu_buf_will_dirty(prev->ds_dbuf, tx);
741 		dsl_dataset_phys(prev)->ds_next_clones_obj =
742 		    zap_create(dp->dp_meta_objset,
743 		    DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
744 	}
745 	VERIFY0(zap_add_int(dp->dp_meta_objset,
746 	    dsl_dataset_phys(prev)->ds_next_clones_obj, ds->ds_object, tx));
747 
748 	dsl_dataset_rele(ds, FTAG);
749 	if (prev != dp->dp_origin_snap)
750 		dsl_dataset_rele(prev, FTAG);
751 	return (0);
752 }
753 
754 void
dsl_pool_upgrade_clones(dsl_pool_t * dp,dmu_tx_t * tx)755 dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
756 {
757 	ASSERT(dmu_tx_is_syncing(tx));
758 	ASSERT(dp->dp_origin_snap != NULL);
759 
760 	VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
761 	    tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
762 }
763 
764 /* ARGSUSED */
765 static int
upgrade_dir_clones_cb(dsl_pool_t * dp,dsl_dataset_t * ds,void * arg)766 upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
767 {
768 	dmu_tx_t *tx = arg;
769 	objset_t *mos = dp->dp_meta_objset;
770 
771 	if (dsl_dir_phys(ds->ds_dir)->dd_origin_obj != 0) {
772 		dsl_dataset_t *origin;
773 
774 		VERIFY0(dsl_dataset_hold_obj(dp,
775 		    dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &origin));
776 
777 		if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) {
778 			dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
779 			dsl_dir_phys(origin->ds_dir)->dd_clones =
780 			    zap_create(mos, DMU_OT_DSL_CLONES, DMU_OT_NONE,
781 			    0, tx);
782 		}
783 
784 		VERIFY0(zap_add_int(dp->dp_meta_objset,
785 		    dsl_dir_phys(origin->ds_dir)->dd_clones,
786 		    ds->ds_object, tx));
787 
788 		dsl_dataset_rele(origin, FTAG);
789 	}
790 	return (0);
791 }
792 
793 void
dsl_pool_upgrade_dir_clones(dsl_pool_t * dp,dmu_tx_t * tx)794 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
795 {
796 	ASSERT(dmu_tx_is_syncing(tx));
797 	uint64_t obj;
798 
799 	(void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
800 	VERIFY0(dsl_pool_open_special_dir(dp,
801 	    FREE_DIR_NAME, &dp->dp_free_dir));
802 
803 	/*
804 	 * We can't use bpobj_alloc(), because spa_version() still
805 	 * returns the old version, and we need a new-version bpobj with
806 	 * subobj support.  So call dmu_object_alloc() directly.
807 	 */
808 	obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
809 	    SPA_OLD_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
810 	VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
811 	    DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
812 	VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
813 
814 	VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
815 	    upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
816 }
817 
818 void
dsl_pool_create_origin(dsl_pool_t * dp,dmu_tx_t * tx)819 dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
820 {
821 	uint64_t dsobj;
822 	dsl_dataset_t *ds;
823 
824 	ASSERT(dmu_tx_is_syncing(tx));
825 	ASSERT(dp->dp_origin_snap == NULL);
826 	ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
827 
828 	/* create the origin dir, ds, & snap-ds */
829 	dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
830 	    NULL, 0, kcred, tx);
831 	VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
832 	dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
833 	VERIFY0(dsl_dataset_hold_obj(dp, dsl_dataset_phys(ds)->ds_prev_snap_obj,
834 	    dp, &dp->dp_origin_snap));
835 	dsl_dataset_rele(ds, FTAG);
836 }
837 
838 taskq_t *
dsl_pool_vnrele_taskq(dsl_pool_t * dp)839 dsl_pool_vnrele_taskq(dsl_pool_t *dp)
840 {
841 	return (dp->dp_vnrele_taskq);
842 }
843 
844 /*
845  * Walk through the pool-wide zap object of temporary snapshot user holds
846  * and release them.
847  */
848 void
dsl_pool_clean_tmp_userrefs(dsl_pool_t * dp)849 dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
850 {
851 	zap_attribute_t za;
852 	zap_cursor_t zc;
853 	objset_t *mos = dp->dp_meta_objset;
854 	uint64_t zapobj = dp->dp_tmp_userrefs_obj;
855 	nvlist_t *holds;
856 
857 	if (zapobj == 0)
858 		return;
859 	ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
860 
861 	holds = fnvlist_alloc();
862 
863 	for (zap_cursor_init(&zc, mos, zapobj);
864 	    zap_cursor_retrieve(&zc, &za) == 0;
865 	    zap_cursor_advance(&zc)) {
866 		char *htag;
867 		nvlist_t *tags;
868 
869 		htag = strchr(za.za_name, '-');
870 		*htag = '\0';
871 		++htag;
872 		if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
873 			tags = fnvlist_alloc();
874 			fnvlist_add_boolean(tags, htag);
875 			fnvlist_add_nvlist(holds, za.za_name, tags);
876 			fnvlist_free(tags);
877 		} else {
878 			fnvlist_add_boolean(tags, htag);
879 		}
880 	}
881 	dsl_dataset_user_release_tmp(dp, holds);
882 	fnvlist_free(holds);
883 	zap_cursor_fini(&zc);
884 }
885 
886 /*
887  * Create the pool-wide zap object for storing temporary snapshot holds.
888  */
889 void
dsl_pool_user_hold_create_obj(dsl_pool_t * dp,dmu_tx_t * tx)890 dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
891 {
892 	objset_t *mos = dp->dp_meta_objset;
893 
894 	ASSERT(dp->dp_tmp_userrefs_obj == 0);
895 	ASSERT(dmu_tx_is_syncing(tx));
896 
897 	dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
898 	    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
899 }
900 
901 static int
dsl_pool_user_hold_rele_impl(dsl_pool_t * dp,uint64_t dsobj,const char * tag,uint64_t now,dmu_tx_t * tx,boolean_t holding)902 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
903     const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
904 {
905 	objset_t *mos = dp->dp_meta_objset;
906 	uint64_t zapobj = dp->dp_tmp_userrefs_obj;
907 	char *name;
908 	int error;
909 
910 	ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
911 	ASSERT(dmu_tx_is_syncing(tx));
912 
913 	/*
914 	 * If the pool was created prior to SPA_VERSION_USERREFS, the
915 	 * zap object for temporary holds might not exist yet.
916 	 */
917 	if (zapobj == 0) {
918 		if (holding) {
919 			dsl_pool_user_hold_create_obj(dp, tx);
920 			zapobj = dp->dp_tmp_userrefs_obj;
921 		} else {
922 			return (SET_ERROR(ENOENT));
923 		}
924 	}
925 
926 	name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
927 	if (holding)
928 		error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
929 	else
930 		error = zap_remove(mos, zapobj, name, tx);
931 	strfree(name);
932 
933 	return (error);
934 }
935 
936 /*
937  * Add a temporary hold for the given dataset object and tag.
938  */
939 int
dsl_pool_user_hold(dsl_pool_t * dp,uint64_t dsobj,const char * tag,uint64_t now,dmu_tx_t * tx)940 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
941     uint64_t now, dmu_tx_t *tx)
942 {
943 	return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
944 }
945 
946 /*
947  * Release a temporary hold for the given dataset object and tag.
948  */
949 int
dsl_pool_user_release(dsl_pool_t * dp,uint64_t dsobj,const char * tag,dmu_tx_t * tx)950 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
951     dmu_tx_t *tx)
952 {
953 	return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, NULL,
954 	    tx, B_FALSE));
955 }
956 
957 /*
958  * DSL Pool Configuration Lock
959  *
960  * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
961  * creation / destruction / rename / property setting).  It must be held for
962  * read to hold a dataset or dsl_dir.  I.e. you must call
963  * dsl_pool_config_enter() or dsl_pool_hold() before calling
964  * dsl_{dataset,dir}_hold{_obj}.  In most circumstances, the dp_config_rwlock
965  * must be held continuously until all datasets and dsl_dirs are released.
966  *
967  * The only exception to this rule is that if a "long hold" is placed on
968  * a dataset, then the dp_config_rwlock may be dropped while the dataset
969  * is still held.  The long hold will prevent the dataset from being
970  * destroyed -- the destroy will fail with EBUSY.  A long hold can be
971  * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
972  * (by calling dsl_{dataset,objset}_{try}own{_obj}).
973  *
974  * Legitimate long-holders (including owners) should be long-running, cancelable
975  * tasks that should cause "zfs destroy" to fail.  This includes DMU
976  * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
977  * "zfs send", and "zfs diff".  There are several other long-holders whose
978  * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
979  *
980  * The usual formula for long-holding would be:
981  * dsl_pool_hold()
982  * dsl_dataset_hold()
983  * ... perform checks ...
984  * dsl_dataset_long_hold()
985  * dsl_pool_rele()
986  * ... perform long-running task ...
987  * dsl_dataset_long_rele()
988  * dsl_dataset_rele()
989  *
990  * Note that when the long hold is released, the dataset is still held but
991  * the pool is not held.  The dataset may change arbitrarily during this time
992  * (e.g. it could be destroyed).  Therefore you shouldn't do anything to the
993  * dataset except release it.
994  *
995  * User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
996  * or modifying operations.
997  *
998  * Modifying operations should generally use dsl_sync_task().  The synctask
999  * infrastructure enforces proper locking strategy with respect to the
1000  * dp_config_rwlock.  See the comment above dsl_sync_task() for details.
1001  *
1002  * Read-only operations will manually hold the pool, then the dataset, obtain
1003  * information from the dataset, then release the pool and dataset.
1004  * dmu_objset_{hold,rele}() are convenience routines that also do the pool
1005  * hold/rele.
1006  */
1007 
1008 int
dsl_pool_hold(const char * name,void * tag,dsl_pool_t ** dp)1009 dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
1010 {
1011 	spa_t *spa;
1012 	int error;
1013 
1014 	error = spa_open(name, &spa, tag);
1015 	if (error == 0) {
1016 		*dp = spa_get_dsl(spa);
1017 		dsl_pool_config_enter(*dp, tag);
1018 	}
1019 	return (error);
1020 }
1021 
1022 void
dsl_pool_rele(dsl_pool_t * dp,void * tag)1023 dsl_pool_rele(dsl_pool_t *dp, void *tag)
1024 {
1025 	dsl_pool_config_exit(dp, tag);
1026 	spa_close(dp->dp_spa, tag);
1027 }
1028 
1029 void
dsl_pool_config_enter(dsl_pool_t * dp,void * tag)1030 dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
1031 {
1032 	/*
1033 	 * We use a "reentrant" reader-writer lock, but not reentrantly.
1034 	 *
1035 	 * The rrwlock can (with the track_all flag) track all reading threads,
1036 	 * which is very useful for debugging which code path failed to release
1037 	 * the lock, and for verifying that the *current* thread does hold
1038 	 * the lock.
1039 	 *
1040 	 * (Unlike a rwlock, which knows that N threads hold it for
1041 	 * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
1042 	 * if any thread holds it for read, even if this thread doesn't).
1043 	 */
1044 	ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1045 	rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
1046 }
1047 
1048 void
dsl_pool_config_enter_prio(dsl_pool_t * dp,void * tag)1049 dsl_pool_config_enter_prio(dsl_pool_t *dp, void *tag)
1050 {
1051 	ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1052 	rrw_enter_read_prio(&dp->dp_config_rwlock, tag);
1053 }
1054 
1055 void
dsl_pool_config_exit(dsl_pool_t * dp,void * tag)1056 dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
1057 {
1058 	rrw_exit(&dp->dp_config_rwlock, tag);
1059 }
1060 
1061 boolean_t
dsl_pool_config_held(dsl_pool_t * dp)1062 dsl_pool_config_held(dsl_pool_t *dp)
1063 {
1064 	return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
1065 }
1066 
1067 boolean_t
dsl_pool_config_held_writer(dsl_pool_t * dp)1068 dsl_pool_config_held_writer(dsl_pool_t *dp)
1069 {
1070 	return (RRW_WRITE_HELD(&dp->dp_config_rwlock));
1071 }
1072