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--- old/usr/src/uts/common/fs/zfs/dsl_pool.c
+++ new/usr/src/uts/common/fs/zfs/dsl_pool.c
1 1 /*
2 2 * CDDL HEADER START
3 3 *
4 4 * The contents of this file are subject to the terms of the
5 5 * Common Development and Distribution License (the "License").
6 6 * You may not use this file except in compliance with the License.
7 7 *
8 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 9 * or http://www.opensolaris.org/os/licensing.
10 10 * See the License for the specific language governing permissions
11 11 * and limitations under the License.
12 12 *
13 13 * When distributing Covered Code, include this CDDL HEADER in each
14 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 15 * If applicable, add the following below this CDDL HEADER, with the
16 16 * fields enclosed by brackets "[]" replaced with your own identifying
17 17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 18 *
19 19 * CDDL HEADER END
20 20 */
21 21 /*
22 22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 23 * Copyright (c) 2013 by Delphix. All rights reserved.
24 24 * Copyright (c) 2013 Steven Hartland. All rights reserved.
25 25 */
26 26
27 27 #include <sys/dsl_pool.h>
28 28 #include <sys/dsl_dataset.h>
29 29 #include <sys/dsl_prop.h>
30 30 #include <sys/dsl_dir.h>
31 31 #include <sys/dsl_synctask.h>
32 32 #include <sys/dsl_scan.h>
33 33 #include <sys/dnode.h>
34 34 #include <sys/dmu_tx.h>
35 35 #include <sys/dmu_objset.h>
36 36 #include <sys/arc.h>
37 37 #include <sys/zap.h>
38 38 #include <sys/zio.h>
39 39 #include <sys/zfs_context.h>
40 40 #include <sys/fs/zfs.h>
41 41 #include <sys/zfs_znode.h>
42 42 #include <sys/spa_impl.h>
43 43 #include <sys/dsl_deadlist.h>
44 44 #include <sys/bptree.h>
45 45 #include <sys/zfeature.h>
46 46 #include <sys/zil_impl.h>
47 47 #include <sys/dsl_userhold.h>
48 48
49 49 /*
50 50 * ZFS Write Throttle
51 51 * ------------------
52 52 *
53 53 * ZFS must limit the rate of incoming writes to the rate at which it is able
54 54 * to sync data modifications to the backend storage. Throttling by too much
55 55 * creates an artificial limit; throttling by too little can only be sustained
56 56 * for short periods and would lead to highly lumpy performance. On a per-pool
57 57 * basis, ZFS tracks the amount of modified (dirty) data. As operations change
58 58 * data, the amount of dirty data increases; as ZFS syncs out data, the amount
59 59 * of dirty data decreases. When the amount of dirty data exceeds a
60 60 * predetermined threshold further modifications are blocked until the amount
61 61 * of dirty data decreases (as data is synced out).
62 62 *
63 63 * The limit on dirty data is tunable, and should be adjusted according to
64 64 * both the IO capacity and available memory of the system. The larger the
65 65 * window, the more ZFS is able to aggregate and amortize metadata (and data)
66 66 * changes. However, memory is a limited resource, and allowing for more dirty
67 67 * data comes at the cost of keeping other useful data in memory (for example
68 68 * ZFS data cached by the ARC).
69 69 *
70 70 * Implementation
71 71 *
72 72 * As buffers are modified dsl_pool_willuse_space() increments both the per-
73 73 * txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
74 74 * dirty space used; dsl_pool_dirty_space() decrements those values as data
75 75 * is synced out from dsl_pool_sync(). While only the poolwide value is
76 76 * relevant, the per-txg value is useful for debugging. The tunable
77 77 * zfs_dirty_data_max determines the dirty space limit. Once that value is
78 78 * exceeded, new writes are halted until space frees up.
79 79 *
80 80 * The zfs_dirty_data_sync tunable dictates the threshold at which we
81 81 * ensure that there is a txg syncing (see the comment in txg.c for a full
82 82 * description of transaction group stages).
83 83 *
84 84 * The IO scheduler uses both the dirty space limit and current amount of
85 85 * dirty data as inputs. Those values affect the number of concurrent IOs ZFS
86 86 * issues. See the comment in vdev_queue.c for details of the IO scheduler.
87 87 *
88 88 * The delay is also calculated based on the amount of dirty data. See the
89 89 * comment above dmu_tx_delay() for details.
90 90 */
91 91
92 92 /*
93 93 * zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
94 94 * capped at zfs_dirty_data_max_max. It can also be overridden in /etc/system.
95 95 */
96 96 uint64_t zfs_dirty_data_max;
97 97 uint64_t zfs_dirty_data_max_max = 4ULL * 1024 * 1024 * 1024;
98 98 int zfs_dirty_data_max_percent = 10;
99 99
100 100 /*
101 101 * If there is at least this much dirty data, push out a txg.
102 102 */
103 103 uint64_t zfs_dirty_data_sync = 64 * 1024 * 1024;
104 104
105 105 /*
106 106 * Once there is this amount of dirty data, the dmu_tx_delay() will kick in
107 107 * and delay each transaction.
108 108 * This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
109 109 */
110 110 int zfs_delay_min_dirty_percent = 60;
111 111
112 112 /*
113 113 * This controls how quickly the delay approaches infinity.
114 114 * Larger values cause it to delay less for a given amount of dirty data.
115 115 * Therefore larger values will cause there to be more dirty data for a
116 116 * given throughput.
117 117 *
118 118 * For the smoothest delay, this value should be about 1 billion divided
119 119 * by the maximum number of operations per second. This will smoothly
120 120 * handle between 10x and 1/10th this number.
121 121 *
122 122 * Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
123 123 * multiply in dmu_tx_delay().
124 124 */
125 125 uint64_t zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
126 126
127 127
128 128 /*
129 129 * XXX someday maybe turn these into #defines, and you have to tune it on a
130 130 * per-pool basis using zfs.conf.
131 131 */
132 132
133 133
134 134 hrtime_t zfs_throttle_delay = MSEC2NSEC(10);
135 135 hrtime_t zfs_throttle_resolution = MSEC2NSEC(10);
136 136
137 137 int
138 138 dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
139 139 {
140 140 uint64_t obj;
141 141 int err;
142 142
143 143 err = zap_lookup(dp->dp_meta_objset,
144 144 dp->dp_root_dir->dd_phys->dd_child_dir_zapobj,
145 145 name, sizeof (obj), 1, &obj);
146 146 if (err)
147 147 return (err);
148 148
149 149 return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
150 150 }
151 151
152 152 static dsl_pool_t *
153 153 dsl_pool_open_impl(spa_t *spa, uint64_t txg)
154 154 {
155 155 dsl_pool_t *dp;
156 156 blkptr_t *bp = spa_get_rootblkptr(spa);
157 157
158 158 dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
159 159 dp->dp_spa = spa;
160 160 dp->dp_meta_rootbp = *bp;
161 161 rrw_init(&dp->dp_config_rwlock, B_TRUE);
162 162 txg_init(dp, txg);
163 163
164 164 txg_list_create(&dp->dp_dirty_datasets,
165 165 offsetof(dsl_dataset_t, ds_dirty_link));
166 166 txg_list_create(&dp->dp_dirty_zilogs,
167 167 offsetof(zilog_t, zl_dirty_link));
168 168 txg_list_create(&dp->dp_dirty_dirs,
169 169 offsetof(dsl_dir_t, dd_dirty_link));
170 170 txg_list_create(&dp->dp_sync_tasks,
171 171 offsetof(dsl_sync_task_t, dst_node));
172 172
173 173 mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
174 174 cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
175 175
176 176 dp->dp_vnrele_taskq = taskq_create("zfs_vn_rele_taskq", 1, minclsyspri,
177 177 1, 4, 0);
178 178
179 179 return (dp);
180 180 }
181 181
182 182 int
183 183 dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
184 184 {
185 185 int err;
186 186 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
187 187
188 188 err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
189 189 &dp->dp_meta_objset);
190 190 if (err != 0)
191 191 dsl_pool_close(dp);
192 192 else
193 193 *dpp = dp;
194 194
195 195 return (err);
196 196 }
197 197
198 198 int
199 199 dsl_pool_open(dsl_pool_t *dp)
200 200 {
201 201 int err;
202 202 dsl_dir_t *dd;
203 203 dsl_dataset_t *ds;
204 204 uint64_t obj;
205 205
206 206 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
207 207 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
208 208 DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1,
209 209 &dp->dp_root_dir_obj);
210 210 if (err)
211 211 goto out;
212 212
213 213 err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
214 214 NULL, dp, &dp->dp_root_dir);
215 215 if (err)
216 216 goto out;
217 217
218 218 err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir);
219 219 if (err)
220 220 goto out;
221 221
222 222 if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
223 223 err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
224 224 if (err)
225 225 goto out;
226 226 err = dsl_dataset_hold_obj(dp, dd->dd_phys->dd_head_dataset_obj,
227 227 FTAG, &ds);
228 228 if (err == 0) {
229 229 err = dsl_dataset_hold_obj(dp,
230 230 ds->ds_phys->ds_prev_snap_obj, dp,
231 231 &dp->dp_origin_snap);
232 232 dsl_dataset_rele(ds, FTAG);
233 233 }
234 234 dsl_dir_rele(dd, dp);
235 235 if (err)
236 236 goto out;
237 237 }
238 238
239 239 if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
240 240 err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
241 241 &dp->dp_free_dir);
242 242 if (err)
243 243 goto out;
244 244
245 245 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
246 246 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
247 247 if (err)
248 248 goto out;
249 249 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
250 250 dp->dp_meta_objset, obj));
251 251 }
252 252
253 253 /*
254 254 * Note: errors ignored, because the leak dir will not exist if we
255 255 * have not encountered a leak yet.
256 256 */
257 257 (void) dsl_pool_open_special_dir(dp, LEAK_DIR_NAME,
258 258 &dp->dp_leak_dir);
259 259
260 260 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
261 261 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
262 262 DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
263 263 &dp->dp_bptree_obj);
264 264 if (err != 0)
265 265 goto out;
266 266 }
267 267
268 268 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_EMPTY_BPOBJ)) {
269 269 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
270 270 DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
271 271 &dp->dp_empty_bpobj);
272 272 if (err != 0)
273 273 goto out;
274 274 }
275 275
276 276 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
277 277 DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
278 278 &dp->dp_tmp_userrefs_obj);
279 279 if (err == ENOENT)
280 280 err = 0;
281 281 if (err)
282 282 goto out;
283 283
284 284 err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
285 285
286 286 out:
287 287 rrw_exit(&dp->dp_config_rwlock, FTAG);
288 288 return (err);
289 289 }
290 290
291 291 void
292 292 dsl_pool_close(dsl_pool_t *dp)
293 293 {
294 294 /*
295 295 * Drop our references from dsl_pool_open().
296 296 *
297 297 * Since we held the origin_snap from "syncing" context (which
298 298 * includes pool-opening context), it actually only got a "ref"
299 299 * and not a hold, so just drop that here.
300 300 */
301 301 if (dp->dp_origin_snap)
302 302 dsl_dataset_rele(dp->dp_origin_snap, dp);
303 303 if (dp->dp_mos_dir)
304 304 dsl_dir_rele(dp->dp_mos_dir, dp);
305 305 if (dp->dp_free_dir)
306 306 dsl_dir_rele(dp->dp_free_dir, dp);
307 307 if (dp->dp_leak_dir)
308 308 dsl_dir_rele(dp->dp_leak_dir, dp);
309 309 if (dp->dp_root_dir)
310 310 dsl_dir_rele(dp->dp_root_dir, dp);
311 311
312 312 bpobj_close(&dp->dp_free_bpobj);
313 313
314 314 /* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
315 315 if (dp->dp_meta_objset)
316 316 dmu_objset_evict(dp->dp_meta_objset);
317 317
318 318 txg_list_destroy(&dp->dp_dirty_datasets);
319 319 txg_list_destroy(&dp->dp_dirty_zilogs);
320 320 txg_list_destroy(&dp->dp_sync_tasks);
321 321 txg_list_destroy(&dp->dp_dirty_dirs);
322 322
323 323 arc_flush(dp->dp_spa);
324 324 txg_fini(dp);
325 325 dsl_scan_fini(dp);
326 326 rrw_destroy(&dp->dp_config_rwlock);
327 327 mutex_destroy(&dp->dp_lock);
328 328 taskq_destroy(dp->dp_vnrele_taskq);
329 329 if (dp->dp_blkstats)
330 330 kmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
331 331 kmem_free(dp, sizeof (dsl_pool_t));
332 332 }
333 333
334 334 dsl_pool_t *
335 335 dsl_pool_create(spa_t *spa, nvlist_t *zplprops, uint64_t txg)
336 336 {
337 337 int err;
338 338 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
339 339 dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
340 340 objset_t *os;
341 341 dsl_dataset_t *ds;
342 342 uint64_t obj;
343 343
344 344 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
345 345
346 346 /* create and open the MOS (meta-objset) */
347 347 dp->dp_meta_objset = dmu_objset_create_impl(spa,
348 348 NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
349 349
350 350 /* create the pool directory */
351 351 err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
352 352 DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
353 353 ASSERT0(err);
354 354
355 355 /* Initialize scan structures */
356 356 VERIFY0(dsl_scan_init(dp, txg));
357 357
358 358 /* create and open the root dir */
359 359 dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
360 360 VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
361 361 NULL, dp, &dp->dp_root_dir));
362 362
363 363 /* create and open the meta-objset dir */
364 364 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
365 365 VERIFY0(dsl_pool_open_special_dir(dp,
366 366 MOS_DIR_NAME, &dp->dp_mos_dir));
367 367
368 368 if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
369 369 /* create and open the free dir */
370 370 (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
371 371 FREE_DIR_NAME, tx);
372 372 VERIFY0(dsl_pool_open_special_dir(dp,
373 373 FREE_DIR_NAME, &dp->dp_free_dir));
374 374
375 375 /* create and open the free_bplist */
376 376 obj = bpobj_alloc(dp->dp_meta_objset, SPA_MAXBLOCKSIZE, tx);
377 377 VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
378 378 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
379 379 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
380 380 dp->dp_meta_objset, obj));
381 381 }
382 382
383 383 if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
384 384 dsl_pool_create_origin(dp, tx);
385 385
386 386 /* create the root dataset */
387 387 obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, 0, tx);
388 388
389 389 /* create the root objset */
390 390 VERIFY0(dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
391 391 os = dmu_objset_create_impl(dp->dp_spa, ds,
392 392 dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
393 393 #ifdef _KERNEL
394 394 zfs_create_fs(os, kcred, zplprops, tx);
395 395 #endif
396 396 dsl_dataset_rele(ds, FTAG);
397 397
398 398 dmu_tx_commit(tx);
399 399
400 400 rrw_exit(&dp->dp_config_rwlock, FTAG);
401 401
402 402 return (dp);
403 403 }
404 404
405 405 /*
406 406 * Account for the meta-objset space in its placeholder dsl_dir.
407 407 */
408 408 void
409 409 dsl_pool_mos_diduse_space(dsl_pool_t *dp,
410 410 int64_t used, int64_t comp, int64_t uncomp)
411 411 {
412 412 ASSERT3U(comp, ==, uncomp); /* it's all metadata */
413 413 mutex_enter(&dp->dp_lock);
414 414 dp->dp_mos_used_delta += used;
415 415 dp->dp_mos_compressed_delta += comp;
416 416 dp->dp_mos_uncompressed_delta += uncomp;
417 417 mutex_exit(&dp->dp_lock);
418 418 }
419 419
420 420 static int
421 421 deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
422 422 {
423 423 dsl_deadlist_t *dl = arg;
424 424 dsl_deadlist_insert(dl, bp, tx);
425 425 return (0);
426 426 }
427 427
428 428 static void
429 429 dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
430 430 {
431 431 zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
432 432 dmu_objset_sync(dp->dp_meta_objset, zio, tx);
433 433 VERIFY0(zio_wait(zio));
434 434 dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
435 435 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
436 436 }
437 437
438 438 static void
439 439 dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
440 440 {
441 441 ASSERT(MUTEX_HELD(&dp->dp_lock));
442 442
443 443 if (delta < 0)
444 444 ASSERT3U(-delta, <=, dp->dp_dirty_total);
445 445
446 446 dp->dp_dirty_total += delta;
447 447
448 448 /*
449 449 * Note: we signal even when increasing dp_dirty_total.
450 450 * This ensures forward progress -- each thread wakes the next waiter.
451 451 */
452 452 if (dp->dp_dirty_total <= zfs_dirty_data_max)
453 453 cv_signal(&dp->dp_spaceavail_cv);
454 454 }
455 455
456 456 void
457 457 dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
458 458 {
459 459 zio_t *zio;
460 460 dmu_tx_t *tx;
461 461 dsl_dir_t *dd;
462 462 dsl_dataset_t *ds;
463 463 objset_t *mos = dp->dp_meta_objset;
464 464 list_t synced_datasets;
465 465
466 466 list_create(&synced_datasets, sizeof (dsl_dataset_t),
467 467 offsetof(dsl_dataset_t, ds_synced_link));
468 468
469 469 tx = dmu_tx_create_assigned(dp, txg);
470 470
471 471 /*
472 472 * Write out all dirty blocks of dirty datasets.
473 473 */
474 474 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
475 475 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
476 476 /*
477 477 * We must not sync any non-MOS datasets twice, because
478 478 * we may have taken a snapshot of them. However, we
479 479 * may sync newly-created datasets on pass 2.
480 480 */
481 481 ASSERT(!list_link_active(&ds->ds_synced_link));
482 482 list_insert_tail(&synced_datasets, ds);
483 483 dsl_dataset_sync(ds, zio, tx);
484 484 }
485 485 VERIFY0(zio_wait(zio));
486 486
487 487 /*
488 488 * We have written all of the accounted dirty data, so our
489 489 * dp_space_towrite should now be zero. However, some seldom-used
490 490 * code paths do not adhere to this (e.g. dbuf_undirty(), also
491 491 * rounding error in dbuf_write_physdone).
492 492 * Shore up the accounting of any dirtied space now.
493 493 */
494 494 dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
495 495
496 496 /*
497 497 * After the data blocks have been written (ensured by the zio_wait()
498 498 * above), update the user/group space accounting.
499 499 */
500 500 for (ds = list_head(&synced_datasets); ds != NULL;
501 501 ds = list_next(&synced_datasets, ds)) {
502 502 dmu_objset_do_userquota_updates(ds->ds_objset, tx);
503 503 }
504 504
505 505 /*
506 506 * Sync the datasets again to push out the changes due to
507 507 * userspace updates. This must be done before we process the
508 508 * sync tasks, so that any snapshots will have the correct
509 509 * user accounting information (and we won't get confused
510 510 * about which blocks are part of the snapshot).
511 511 */
512 512 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
513 513 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
514 514 ASSERT(list_link_active(&ds->ds_synced_link));
515 515 dmu_buf_rele(ds->ds_dbuf, ds);
516 516 dsl_dataset_sync(ds, zio, tx);
517 517 }
518 518 VERIFY0(zio_wait(zio));
519 519
520 520 /*
521 521 * Now that the datasets have been completely synced, we can
522 522 * clean up our in-memory structures accumulated while syncing:
523 523 *
524 524 * - move dead blocks from the pending deadlist to the on-disk deadlist
525 525 * - release hold from dsl_dataset_dirty()
526 526 */
527 527 while ((ds = list_remove_head(&synced_datasets)) != NULL) {
528 528 objset_t *os = ds->ds_objset;
529 529 bplist_iterate(&ds->ds_pending_deadlist,
530 530 deadlist_enqueue_cb, &ds->ds_deadlist, tx);
531 531 ASSERT(!dmu_objset_is_dirty(os, txg));
532 532 dmu_buf_rele(ds->ds_dbuf, ds);
533 533 }
534 534 while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
535 535 dsl_dir_sync(dd, tx);
536 536 }
537 537
538 538 /*
539 539 * The MOS's space is accounted for in the pool/$MOS
540 540 * (dp_mos_dir). We can't modify the mos while we're syncing
541 541 * it, so we remember the deltas and apply them here.
542 542 */
543 543 if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
544 544 dp->dp_mos_uncompressed_delta != 0) {
545 545 dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
546 546 dp->dp_mos_used_delta,
547 547 dp->dp_mos_compressed_delta,
548 548 dp->dp_mos_uncompressed_delta, tx);
549 549 dp->dp_mos_used_delta = 0;
550 550 dp->dp_mos_compressed_delta = 0;
551 551 dp->dp_mos_uncompressed_delta = 0;
552 552 }
553 553
554 554 if (list_head(&mos->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
555 555 list_head(&mos->os_free_dnodes[txg & TXG_MASK]) != NULL) {
556 556 dsl_pool_sync_mos(dp, tx);
557 557 }
558 558
559 559 /*
560 560 * If we modify a dataset in the same txg that we want to destroy it,
561 561 * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
562 562 * dsl_dir_destroy_check() will fail if there are unexpected holds.
563 563 * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
564 564 * and clearing the hold on it) before we process the sync_tasks.
565 565 * The MOS data dirtied by the sync_tasks will be synced on the next
566 566 * pass.
567 567 */
568 568 if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
569 569 dsl_sync_task_t *dst;
570 570 /*
571 571 * No more sync tasks should have been added while we
572 572 * were syncing.
573 573 */
574 574 ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
575 575 while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
576 576 dsl_sync_task_sync(dst, tx);
577 577 }
578 578
579 579 dmu_tx_commit(tx);
580 580
581 581 DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
582 582 }
583 583
584 584 void
585 585 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
586 586 {
587 587 zilog_t *zilog;
588 588
589 589 while (zilog = txg_list_remove(&dp->dp_dirty_zilogs, txg)) {
590 590 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
591 591 zil_clean(zilog, txg);
592 592 ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
593 593 dmu_buf_rele(ds->ds_dbuf, zilog);
594 594 }
595 595 ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
596 596 }
597 597
598 598 /*
599 599 * TRUE if the current thread is the tx_sync_thread or if we
600 600 * are being called from SPA context during pool initialization.
601 601 */
602 602 int
603 603 dsl_pool_sync_context(dsl_pool_t *dp)
604 604 {
605 605 return (curthread == dp->dp_tx.tx_sync_thread ||
606 606 spa_is_initializing(dp->dp_spa));
607 607 }
608 608
609 609 uint64_t
610 610 dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
611 611 {
612 612 uint64_t space, resv;
613 613
614 614 /*
615 615 * Reserve about 1.6% (1/64), or at least 32MB, for allocation
616 616 * efficiency.
617 617 * XXX The intent log is not accounted for, so it must fit
618 618 * within this slop.
619 619 *
620 620 * If we're trying to assess whether it's OK to do a free,
621 621 * cut the reservation in half to allow forward progress
622 622 * (e.g. make it possible to rm(1) files from a full pool).
623 623 */
624 624 space = spa_get_dspace(dp->dp_spa);
625 625 resv = MAX(space >> 6, SPA_MINDEVSIZE >> 1);
626 626 if (netfree)
627 627 resv >>= 1;
628 628
629 629 return (space - resv);
630 630 }
631 631
632 632 boolean_t
633 633 dsl_pool_need_dirty_delay(dsl_pool_t *dp)
634 634 {
635 635 uint64_t delay_min_bytes =
636 636 zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
637 637 boolean_t rv;
638 638
639 639 mutex_enter(&dp->dp_lock);
640 640 if (dp->dp_dirty_total > zfs_dirty_data_sync)
641 641 txg_kick(dp);
642 642 rv = (dp->dp_dirty_total > delay_min_bytes);
643 643 mutex_exit(&dp->dp_lock);
644 644 return (rv);
645 645 }
646 646
647 647 void
648 648 dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
649 649 {
650 650 if (space > 0) {
651 651 mutex_enter(&dp->dp_lock);
652 652 dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
653 653 dsl_pool_dirty_delta(dp, space);
654 654 mutex_exit(&dp->dp_lock);
655 655 }
656 656 }
657 657
658 658 void
659 659 dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
660 660 {
661 661 ASSERT3S(space, >=, 0);
662 662 if (space == 0)
663 663 return;
664 664 mutex_enter(&dp->dp_lock);
665 665 if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
666 666 /* XXX writing something we didn't dirty? */
667 667 space = dp->dp_dirty_pertxg[txg & TXG_MASK];
668 668 }
669 669 ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
670 670 dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
671 671 ASSERT3U(dp->dp_dirty_total, >=, space);
672 672 dsl_pool_dirty_delta(dp, -space);
673 673 mutex_exit(&dp->dp_lock);
674 674 }
675 675
676 676 /* ARGSUSED */
677 677 static int
678 678 upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
679 679 {
680 680 dmu_tx_t *tx = arg;
681 681 dsl_dataset_t *ds, *prev = NULL;
682 682 int err;
683 683
684 684 err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
685 685 if (err)
686 686 return (err);
687 687
688 688 while (ds->ds_phys->ds_prev_snap_obj != 0) {
689 689 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
690 690 FTAG, &prev);
691 691 if (err) {
692 692 dsl_dataset_rele(ds, FTAG);
693 693 return (err);
694 694 }
695 695
696 696 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object)
697 697 break;
698 698 dsl_dataset_rele(ds, FTAG);
699 699 ds = prev;
700 700 prev = NULL;
701 701 }
702 702
703 703 if (prev == NULL) {
704 704 prev = dp->dp_origin_snap;
705 705
706 706 /*
707 707 * The $ORIGIN can't have any data, or the accounting
708 708 * will be wrong.
709 709 */
710 710 ASSERT0(prev->ds_phys->ds_bp.blk_birth);
711 711
712 712 /* The origin doesn't get attached to itself */
713 713 if (ds->ds_object == prev->ds_object) {
714 714 dsl_dataset_rele(ds, FTAG);
715 715 return (0);
716 716 }
717 717
718 718 dmu_buf_will_dirty(ds->ds_dbuf, tx);
719 719 ds->ds_phys->ds_prev_snap_obj = prev->ds_object;
720 720 ds->ds_phys->ds_prev_snap_txg = prev->ds_phys->ds_creation_txg;
721 721
722 722 dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
723 723 ds->ds_dir->dd_phys->dd_origin_obj = prev->ds_object;
724 724
725 725 dmu_buf_will_dirty(prev->ds_dbuf, tx);
726 726 prev->ds_phys->ds_num_children++;
727 727
728 728 if (ds->ds_phys->ds_next_snap_obj == 0) {
729 729 ASSERT(ds->ds_prev == NULL);
730 730 VERIFY0(dsl_dataset_hold_obj(dp,
731 731 ds->ds_phys->ds_prev_snap_obj, ds, &ds->ds_prev));
732 732 }
733 733 }
734 734
735 735 ASSERT3U(ds->ds_dir->dd_phys->dd_origin_obj, ==, prev->ds_object);
736 736 ASSERT3U(ds->ds_phys->ds_prev_snap_obj, ==, prev->ds_object);
737 737
738 738 if (prev->ds_phys->ds_next_clones_obj == 0) {
739 739 dmu_buf_will_dirty(prev->ds_dbuf, tx);
740 740 prev->ds_phys->ds_next_clones_obj =
741 741 zap_create(dp->dp_meta_objset,
742 742 DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
743 743 }
744 744 VERIFY0(zap_add_int(dp->dp_meta_objset,
745 745 prev->ds_phys->ds_next_clones_obj, ds->ds_object, tx));
746 746
747 747 dsl_dataset_rele(ds, FTAG);
748 748 if (prev != dp->dp_origin_snap)
749 749 dsl_dataset_rele(prev, FTAG);
750 750 return (0);
751 751 }
752 752
753 753 void
754 754 dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
755 755 {
756 756 ASSERT(dmu_tx_is_syncing(tx));
757 757 ASSERT(dp->dp_origin_snap != NULL);
758 758
759 759 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
760 760 tx, DS_FIND_CHILDREN));
761 761 }
762 762
763 763 /* ARGSUSED */
764 764 static int
765 765 upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
766 766 {
767 767 dmu_tx_t *tx = arg;
768 768 objset_t *mos = dp->dp_meta_objset;
769 769
770 770 if (ds->ds_dir->dd_phys->dd_origin_obj != 0) {
771 771 dsl_dataset_t *origin;
772 772
773 773 VERIFY0(dsl_dataset_hold_obj(dp,
774 774 ds->ds_dir->dd_phys->dd_origin_obj, FTAG, &origin));
775 775
776 776 if (origin->ds_dir->dd_phys->dd_clones == 0) {
777 777 dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
778 778 origin->ds_dir->dd_phys->dd_clones = zap_create(mos,
779 779 DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
780 780 }
781 781
782 782 VERIFY0(zap_add_int(dp->dp_meta_objset,
783 783 origin->ds_dir->dd_phys->dd_clones, ds->ds_object, tx));
784 784
785 785 dsl_dataset_rele(origin, FTAG);
786 786 }
787 787 return (0);
788 788 }
789 789
790 790 void
791 791 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
792 792 {
793 793 ASSERT(dmu_tx_is_syncing(tx));
794 794 uint64_t obj;
795 795
796 796 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
797 797 VERIFY0(dsl_pool_open_special_dir(dp,
798 798 FREE_DIR_NAME, &dp->dp_free_dir));
799 799
800 800 /*
801 801 * We can't use bpobj_alloc(), because spa_version() still
802 802 * returns the old version, and we need a new-version bpobj with
803 803 * subobj support. So call dmu_object_alloc() directly.
804 804 */
805 805 obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
806 806 SPA_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
807 807 VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
808 808 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
809 809 VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
810 810
811 811 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
812 812 upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN));
813 813 }
814 814
815 815 void
816 816 dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
817 817 {
818 818 uint64_t dsobj;
819 819 dsl_dataset_t *ds;
820 820
821 821 ASSERT(dmu_tx_is_syncing(tx));
822 822 ASSERT(dp->dp_origin_snap == NULL);
823 823 ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
824 824
825 825 /* create the origin dir, ds, & snap-ds */
826 826 dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
827 827 NULL, 0, kcred, tx);
828 828 VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
829 829 dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
830 830 VERIFY0(dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
831 831 dp, &dp->dp_origin_snap));
832 832 dsl_dataset_rele(ds, FTAG);
833 833 }
834 834
835 835 taskq_t *
836 836 dsl_pool_vnrele_taskq(dsl_pool_t *dp)
837 837 {
838 838 return (dp->dp_vnrele_taskq);
839 839 }
840 840
841 841 /*
842 842 * Walk through the pool-wide zap object of temporary snapshot user holds
843 843 * and release them.
844 844 */
845 845 void
846 846 dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
847 847 {
848 848 zap_attribute_t za;
849 849 zap_cursor_t zc;
850 850 objset_t *mos = dp->dp_meta_objset;
851 851 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
852 852 nvlist_t *holds;
853 853
854 854 if (zapobj == 0)
855 855 return;
856 856 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
857 857
858 858 holds = fnvlist_alloc();
859 859
860 860 for (zap_cursor_init(&zc, mos, zapobj);
861 861 zap_cursor_retrieve(&zc, &za) == 0;
862 862 zap_cursor_advance(&zc)) {
863 863 char *htag;
864 864 nvlist_t *tags;
865 865
866 866 htag = strchr(za.za_name, '-');
867 867 *htag = '\0';
868 868 ++htag;
869 869 if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
870 870 tags = fnvlist_alloc();
871 871 fnvlist_add_boolean(tags, htag);
872 872 fnvlist_add_nvlist(holds, za.za_name, tags);
873 873 fnvlist_free(tags);
874 874 } else {
875 875 fnvlist_add_boolean(tags, htag);
876 876 }
877 877 }
878 878 dsl_dataset_user_release_tmp(dp, holds);
879 879 fnvlist_free(holds);
880 880 zap_cursor_fini(&zc);
881 881 }
882 882
883 883 /*
884 884 * Create the pool-wide zap object for storing temporary snapshot holds.
885 885 */
886 886 void
887 887 dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
888 888 {
889 889 objset_t *mos = dp->dp_meta_objset;
890 890
891 891 ASSERT(dp->dp_tmp_userrefs_obj == 0);
892 892 ASSERT(dmu_tx_is_syncing(tx));
893 893
894 894 dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
895 895 DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
896 896 }
897 897
898 898 static int
899 899 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
900 900 const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
901 901 {
902 902 objset_t *mos = dp->dp_meta_objset;
903 903 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
904 904 char *name;
905 905 int error;
906 906
907 907 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
908 908 ASSERT(dmu_tx_is_syncing(tx));
909 909
910 910 /*
911 911 * If the pool was created prior to SPA_VERSION_USERREFS, the
912 912 * zap object for temporary holds might not exist yet.
913 913 */
914 914 if (zapobj == 0) {
915 915 if (holding) {
916 916 dsl_pool_user_hold_create_obj(dp, tx);
917 917 zapobj = dp->dp_tmp_userrefs_obj;
918 918 } else {
919 919 return (SET_ERROR(ENOENT));
920 920 }
921 921 }
922 922
923 923 name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
924 924 if (holding)
925 925 error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
926 926 else
927 927 error = zap_remove(mos, zapobj, name, tx);
928 928 strfree(name);
929 929
930 930 return (error);
931 931 }
932 932
933 933 /*
934 934 * Add a temporary hold for the given dataset object and tag.
935 935 */
936 936 int
937 937 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
938 938 uint64_t now, dmu_tx_t *tx)
939 939 {
940 940 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
941 941 }
942 942
943 943 /*
944 944 * Release a temporary hold for the given dataset object and tag.
945 945 */
946 946 int
947 947 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
948 948 dmu_tx_t *tx)
949 949 {
950 950 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, NULL,
951 951 tx, B_FALSE));
952 952 }
953 953
954 954 /*
955 955 * DSL Pool Configuration Lock
956 956 *
957 957 * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
958 958 * creation / destruction / rename / property setting). It must be held for
959 959 * read to hold a dataset or dsl_dir. I.e. you must call
960 960 * dsl_pool_config_enter() or dsl_pool_hold() before calling
961 961 * dsl_{dataset,dir}_hold{_obj}. In most circumstances, the dp_config_rwlock
962 962 * must be held continuously until all datasets and dsl_dirs are released.
963 963 *
964 964 * The only exception to this rule is that if a "long hold" is placed on
965 965 * a dataset, then the dp_config_rwlock may be dropped while the dataset
966 966 * is still held. The long hold will prevent the dataset from being
967 967 * destroyed -- the destroy will fail with EBUSY. A long hold can be
968 968 * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
969 969 * (by calling dsl_{dataset,objset}_{try}own{_obj}).
970 970 *
971 971 * Legitimate long-holders (including owners) should be long-running, cancelable
972 972 * tasks that should cause "zfs destroy" to fail. This includes DMU
973 973 * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
974 974 * "zfs send", and "zfs diff". There are several other long-holders whose
975 975 * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
976 976 *
977 977 * The usual formula for long-holding would be:
978 978 * dsl_pool_hold()
979 979 * dsl_dataset_hold()
980 980 * ... perform checks ...
981 981 * dsl_dataset_long_hold()
982 982 * dsl_pool_rele()
983 983 * ... perform long-running task ...
984 984 * dsl_dataset_long_rele()
985 985 * dsl_dataset_rele()
986 986 *
987 987 * Note that when the long hold is released, the dataset is still held but
988 988 * the pool is not held. The dataset may change arbitrarily during this time
989 989 * (e.g. it could be destroyed). Therefore you shouldn't do anything to the
990 990 * dataset except release it.
991 991 *
992 992 * User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
993 993 * or modifying operations.
994 994 *
995 995 * Modifying operations should generally use dsl_sync_task(). The synctask
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996 996 * infrastructure enforces proper locking strategy with respect to the
997 997 * dp_config_rwlock. See the comment above dsl_sync_task() for details.
998 998 *
999 999 * Read-only operations will manually hold the pool, then the dataset, obtain
1000 1000 * information from the dataset, then release the pool and dataset.
1001 1001 * dmu_objset_{hold,rele}() are convenience routines that also do the pool
1002 1002 * hold/rele.
1003 1003 */
1004 1004
1005 1005 int
1006 -dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
1006 +dsl_pool_hold_lock(const char *name, void *tag, dsl_pool_t **dp, int lock)
1007 1007 {
1008 1008 spa_t *spa;
1009 1009 int error;
1010 1010
1011 - error = spa_open(name, &spa, tag);
1011 + error = spa_open_lock(name, &spa, tag, lock);
1012 1012 if (error == 0) {
1013 1013 *dp = spa_get_dsl(spa);
1014 1014 dsl_pool_config_enter(*dp, tag);
1015 1015 }
1016 1016 return (error);
1017 1017 }
1018 1018
1019 +int
1020 +dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
1021 +{
1022 + return (dsl_pool_hold_lock(name, tag, dp, 1));
1023 +}
1024 +
1019 1025 void
1020 1026 dsl_pool_rele(dsl_pool_t *dp, void *tag)
1021 1027 {
1022 1028 dsl_pool_config_exit(dp, tag);
1023 1029 spa_close(dp->dp_spa, tag);
1024 1030 }
1025 1031
1026 1032 void
1027 1033 dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
1028 1034 {
1029 1035 /*
1030 1036 * We use a "reentrant" reader-writer lock, but not reentrantly.
1031 1037 *
1032 1038 * The rrwlock can (with the track_all flag) track all reading threads,
1033 1039 * which is very useful for debugging which code path failed to release
1034 1040 * the lock, and for verifying that the *current* thread does hold
1035 1041 * the lock.
1036 1042 *
1037 1043 * (Unlike a rwlock, which knows that N threads hold it for
1038 1044 * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
1039 1045 * if any thread holds it for read, even if this thread doesn't).
1040 1046 */
1041 1047 ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1042 1048 rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
1043 1049 }
1044 1050
1045 1051 void
1046 1052 dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
1047 1053 {
1048 1054 rrw_exit(&dp->dp_config_rwlock, tag);
1049 1055 }
1050 1056
1051 1057 boolean_t
1052 1058 dsl_pool_config_held(dsl_pool_t *dp)
1053 1059 {
1054 1060 return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
1055 1061 }
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