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.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
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]
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2011, 2020 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 * Copyright 2016 Nexenta Systems, Inc. All rights reserved.
29 #include <sys/dsl_pool.h>
30 #include <sys/dsl_dataset.h>
31 #include <sys/dsl_prop.h>
32 #include <sys/dsl_dir.h>
33 #include <sys/dsl_synctask.h>
34 #include <sys/dsl_scan.h>
35 #include <sys/dnode.h>
36 #include <sys/dmu_tx.h>
37 #include <sys/dmu_objset.h>
41 #include <sys/zfs_context.h>
42 #include <sys/fs/zfs.h>
43 #include <sys/zfs_znode.h>
44 #include <sys/spa_impl.h>
45 #include <sys/vdev_impl.h>
46 #include <sys/metaslab_impl.h>
47 #include <sys/bptree.h>
48 #include <sys/zfeature.h>
49 #include <sys/zil_impl.h>
50 #include <sys/dsl_userhold.h>
51 #include <sys/trace_zfs.h>
58 * ZFS must limit the rate of incoming writes to the rate at which it is able
59 * to sync data modifications to the backend storage. Throttling by too much
60 * creates an artificial limit; throttling by too little can only be sustained
61 * for short periods and would lead to highly lumpy performance. On a per-pool
62 * basis, ZFS tracks the amount of modified (dirty) data. As operations change
63 * data, the amount of dirty data increases; as ZFS syncs out data, the amount
64 * of dirty data decreases. When the amount of dirty data exceeds a
65 * predetermined threshold further modifications are blocked until the amount
66 * of dirty data decreases (as data is synced out).
68 * The limit on dirty data is tunable, and should be adjusted according to
69 * both the IO capacity and available memory of the system. The larger the
70 * window, the more ZFS is able to aggregate and amortize metadata (and data)
71 * changes. However, memory is a limited resource, and allowing for more dirty
72 * data comes at the cost of keeping other useful data in memory (for example
73 * ZFS data cached by the ARC).
77 * As buffers are modified dsl_pool_willuse_space() increments both the per-
78 * txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
79 * dirty space used; dsl_pool_dirty_space() decrements those values as data
80 * is synced out from dsl_pool_sync(). While only the poolwide value is
81 * relevant, the per-txg value is useful for debugging. The tunable
82 * zfs_dirty_data_max determines the dirty space limit. Once that value is
83 * exceeded, new writes are halted until space frees up.
85 * The zfs_dirty_data_sync_percent tunable dictates the threshold at which we
86 * ensure that there is a txg syncing (see the comment in txg.c for a full
87 * description of transaction group stages).
89 * The IO scheduler uses both the dirty space limit and current amount of
90 * dirty data as inputs. Those values affect the number of concurrent IOs ZFS
91 * issues. See the comment in vdev_queue.c for details of the IO scheduler.
93 * The delay is also calculated based on the amount of dirty data. See the
94 * comment above dmu_tx_delay() for details.
98 * zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
99 * capped at zfs_dirty_data_max_max. It can also be overridden with a module
102 uint64_t zfs_dirty_data_max = 0;
103 uint64_t zfs_dirty_data_max_max = 0;
104 uint_t zfs_dirty_data_max_percent = 10;
105 uint_t zfs_dirty_data_max_max_percent = 25;
108 * The upper limit of TX_WRITE log data. Write operations are throttled
109 * when approaching the limit until log data is cleared out after txg sync.
110 * It only counts TX_WRITE log with WR_COPIED or WR_NEED_COPY.
112 uint64_t zfs_wrlog_data_max = 0;
115 * If there's at least this much dirty data (as a percentage of
116 * zfs_dirty_data_max), push out a txg. This should be less than
117 * zfs_vdev_async_write_active_min_dirty_percent.
119 static uint_t zfs_dirty_data_sync_percent = 20;
122 * Once there is this amount of dirty data, the dmu_tx_delay() will kick in
123 * and delay each transaction.
124 * This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
126 uint_t zfs_delay_min_dirty_percent = 60;
129 * This controls how quickly the delay approaches infinity.
130 * Larger values cause it to delay more for a given amount of dirty data.
131 * Therefore larger values will cause there to be less dirty data for a
134 * For the smoothest delay, this value should be about 1 billion divided
135 * by the maximum number of operations per second. This will smoothly
136 * handle between 10x and 1/10th this number.
138 * Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
139 * multiply in dmu_tx_delay().
141 uint64_t zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
144 * This determines the number of threads used by the dp_sync_taskq.
146 static int zfs_sync_taskq_batch_pct = 75;
149 * These tunables determine the behavior of how zil_itxg_clean() is
150 * called via zil_clean() in the context of spa_sync(). When an itxg
151 * list needs to be cleaned, TQ_NOSLEEP will be used when dispatching.
152 * If the dispatch fails, the call to zil_itxg_clean() will occur
153 * synchronously in the context of spa_sync(), which can negatively
154 * impact the performance of spa_sync() (e.g. in the case of the itxg
155 * list having a large number of itxs that needs to be cleaned).
157 * Thus, these tunables can be used to manipulate the behavior of the
158 * taskq used by zil_clean(); they determine the number of taskq entries
159 * that are pre-populated when the taskq is first created (via the
160 * "zfs_zil_clean_taskq_minalloc" tunable) and the maximum number of
161 * taskq entries that are cached after an on-demand allocation (via the
162 * "zfs_zil_clean_taskq_maxalloc").
164 * The idea being, we want to try reasonably hard to ensure there will
165 * already be a taskq entry pre-allocated by the time that it is needed
166 * by zil_clean(). This way, we can avoid the possibility of an
167 * on-demand allocation of a new taskq entry from failing, which would
168 * result in zil_itxg_clean() being called synchronously from zil_clean()
169 * (which can adversely affect performance of spa_sync()).
171 * Additionally, the number of threads used by the taskq can be
172 * configured via the "zfs_zil_clean_taskq_nthr_pct" tunable.
174 static int zfs_zil_clean_taskq_nthr_pct = 100;
175 static int zfs_zil_clean_taskq_minalloc = 1024;
176 static int zfs_zil_clean_taskq_maxalloc = 1024 * 1024;
179 dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
184 err = zap_lookup(dp->dp_meta_objset,
185 dsl_dir_phys(dp->dp_root_dir)->dd_child_dir_zapobj,
186 name, sizeof (obj), 1, &obj);
190 return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
194 dsl_pool_open_impl(spa_t *spa, uint64_t txg)
197 blkptr_t *bp = spa_get_rootblkptr(spa);
199 dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
201 dp->dp_meta_rootbp = *bp;
202 rrw_init(&dp->dp_config_rwlock, B_TRUE);
206 txg_list_create(&dp->dp_dirty_datasets, spa,
207 offsetof(dsl_dataset_t, ds_dirty_link));
208 txg_list_create(&dp->dp_dirty_zilogs, spa,
209 offsetof(zilog_t, zl_dirty_link));
210 txg_list_create(&dp->dp_dirty_dirs, spa,
211 offsetof(dsl_dir_t, dd_dirty_link));
212 txg_list_create(&dp->dp_sync_tasks, spa,
213 offsetof(dsl_sync_task_t, dst_node));
214 txg_list_create(&dp->dp_early_sync_tasks, spa,
215 offsetof(dsl_sync_task_t, dst_node));
217 dp->dp_sync_taskq = taskq_create("dp_sync_taskq",
218 zfs_sync_taskq_batch_pct, minclsyspri, 1, INT_MAX,
219 TASKQ_THREADS_CPU_PCT);
221 dp->dp_zil_clean_taskq = taskq_create("dp_zil_clean_taskq",
222 zfs_zil_clean_taskq_nthr_pct, minclsyspri,
223 zfs_zil_clean_taskq_minalloc,
224 zfs_zil_clean_taskq_maxalloc,
225 TASKQ_PREPOPULATE | TASKQ_THREADS_CPU_PCT);
227 mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
228 cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
230 aggsum_init(&dp->dp_wrlog_total, 0);
231 for (int i = 0; i < TXG_SIZE; i++) {
232 aggsum_init(&dp->dp_wrlog_pertxg[i], 0);
235 dp->dp_zrele_taskq = taskq_create("z_zrele", 100, defclsyspri,
236 boot_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC |
237 TASKQ_THREADS_CPU_PCT);
238 dp->dp_unlinked_drain_taskq = taskq_create("z_unlinked_drain",
239 100, defclsyspri, boot_ncpus, INT_MAX,
240 TASKQ_PREPOPULATE | TASKQ_DYNAMIC | TASKQ_THREADS_CPU_PCT);
246 dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
249 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
252 * Initialize the caller's dsl_pool_t structure before we actually open
253 * the meta objset. This is done because a self-healing write zio may
254 * be issued as part of dmu_objset_open_impl() and the spa needs its
255 * dsl_pool_t initialized in order to handle the write.
259 err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
260 &dp->dp_meta_objset);
270 dsl_pool_open(dsl_pool_t *dp)
277 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
278 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
279 DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1,
280 &dp->dp_root_dir_obj);
284 err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
285 NULL, dp, &dp->dp_root_dir);
289 err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir);
293 if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
294 err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
297 err = dsl_dataset_hold_obj(dp,
298 dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds);
300 err = dsl_dataset_hold_obj(dp,
301 dsl_dataset_phys(ds)->ds_prev_snap_obj, dp,
302 &dp->dp_origin_snap);
303 dsl_dataset_rele(ds, FTAG);
305 dsl_dir_rele(dd, dp);
310 if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
311 err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
316 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
317 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
320 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
321 dp->dp_meta_objset, obj));
324 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS)) {
325 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
326 DMU_POOL_OBSOLETE_BPOBJ, sizeof (uint64_t), 1, &obj);
328 VERIFY0(bpobj_open(&dp->dp_obsolete_bpobj,
329 dp->dp_meta_objset, obj));
330 } else if (err == ENOENT) {
332 * We might not have created the remap bpobj yet.
340 * Note: errors ignored, because the these special dirs, used for
341 * space accounting, are only created on demand.
343 (void) dsl_pool_open_special_dir(dp, LEAK_DIR_NAME,
346 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
347 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
348 DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
354 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_EMPTY_BPOBJ)) {
355 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
356 DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
357 &dp->dp_empty_bpobj);
362 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
363 DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
364 &dp->dp_tmp_userrefs_obj);
370 err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
373 rrw_exit(&dp->dp_config_rwlock, FTAG);
378 dsl_pool_close(dsl_pool_t *dp)
381 * Drop our references from dsl_pool_open().
383 * Since we held the origin_snap from "syncing" context (which
384 * includes pool-opening context), it actually only got a "ref"
385 * and not a hold, so just drop that here.
387 if (dp->dp_origin_snap != NULL)
388 dsl_dataset_rele(dp->dp_origin_snap, dp);
389 if (dp->dp_mos_dir != NULL)
390 dsl_dir_rele(dp->dp_mos_dir, dp);
391 if (dp->dp_free_dir != NULL)
392 dsl_dir_rele(dp->dp_free_dir, dp);
393 if (dp->dp_leak_dir != NULL)
394 dsl_dir_rele(dp->dp_leak_dir, dp);
395 if (dp->dp_root_dir != NULL)
396 dsl_dir_rele(dp->dp_root_dir, dp);
398 bpobj_close(&dp->dp_free_bpobj);
399 bpobj_close(&dp->dp_obsolete_bpobj);
401 /* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
402 if (dp->dp_meta_objset != NULL)
403 dmu_objset_evict(dp->dp_meta_objset);
405 txg_list_destroy(&dp->dp_dirty_datasets);
406 txg_list_destroy(&dp->dp_dirty_zilogs);
407 txg_list_destroy(&dp->dp_sync_tasks);
408 txg_list_destroy(&dp->dp_early_sync_tasks);
409 txg_list_destroy(&dp->dp_dirty_dirs);
411 taskq_destroy(dp->dp_zil_clean_taskq);
412 taskq_destroy(dp->dp_sync_taskq);
415 * We can't set retry to TRUE since we're explicitly specifying
416 * a spa to flush. This is good enough; any missed buffers for
417 * this spa won't cause trouble, and they'll eventually fall
418 * out of the ARC just like any other unused buffer.
420 arc_flush(dp->dp_spa, FALSE);
422 mmp_fini(dp->dp_spa);
425 dmu_buf_user_evict_wait();
427 rrw_destroy(&dp->dp_config_rwlock);
428 mutex_destroy(&dp->dp_lock);
429 cv_destroy(&dp->dp_spaceavail_cv);
431 ASSERT0(aggsum_value(&dp->dp_wrlog_total));
432 aggsum_fini(&dp->dp_wrlog_total);
433 for (int i = 0; i < TXG_SIZE; i++) {
434 ASSERT0(aggsum_value(&dp->dp_wrlog_pertxg[i]));
435 aggsum_fini(&dp->dp_wrlog_pertxg[i]);
438 taskq_destroy(dp->dp_unlinked_drain_taskq);
439 taskq_destroy(dp->dp_zrele_taskq);
440 if (dp->dp_blkstats != NULL)
441 vmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
442 kmem_free(dp, sizeof (dsl_pool_t));
446 dsl_pool_create_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx)
450 * Currently, we only create the obsolete_bpobj where there are
451 * indirect vdevs with referenced mappings.
453 ASSERT(spa_feature_is_active(dp->dp_spa, SPA_FEATURE_DEVICE_REMOVAL));
454 /* create and open the obsolete_bpobj */
455 obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
456 VERIFY0(bpobj_open(&dp->dp_obsolete_bpobj, dp->dp_meta_objset, obj));
457 VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
458 DMU_POOL_OBSOLETE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
459 spa_feature_incr(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
463 dsl_pool_destroy_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx)
465 spa_feature_decr(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
466 VERIFY0(zap_remove(dp->dp_meta_objset,
467 DMU_POOL_DIRECTORY_OBJECT,
468 DMU_POOL_OBSOLETE_BPOBJ, tx));
469 bpobj_free(dp->dp_meta_objset,
470 dp->dp_obsolete_bpobj.bpo_object, tx);
471 bpobj_close(&dp->dp_obsolete_bpobj);
475 dsl_pool_create(spa_t *spa, nvlist_t *zplprops __attribute__((unused)),
476 dsl_crypto_params_t *dcp, uint64_t txg)
479 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
480 dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
484 objset_t *os __attribute__((unused));
489 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
491 /* create and open the MOS (meta-objset) */
492 dp->dp_meta_objset = dmu_objset_create_impl(spa,
493 NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
494 spa->spa_meta_objset = dp->dp_meta_objset;
496 /* create the pool directory */
497 err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
498 DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
501 /* Initialize scan structures */
502 VERIFY0(dsl_scan_init(dp, txg));
504 /* create and open the root dir */
505 dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
506 VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
507 NULL, dp, &dp->dp_root_dir));
509 /* create and open the meta-objset dir */
510 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
511 VERIFY0(dsl_pool_open_special_dir(dp,
512 MOS_DIR_NAME, &dp->dp_mos_dir));
514 if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
515 /* create and open the free dir */
516 (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
518 VERIFY0(dsl_pool_open_special_dir(dp,
519 FREE_DIR_NAME, &dp->dp_free_dir));
521 /* create and open the free_bplist */
522 obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
523 VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
524 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
525 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
526 dp->dp_meta_objset, obj));
529 if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
530 dsl_pool_create_origin(dp, tx);
533 * Some features may be needed when creating the root dataset, so we
534 * create the feature objects here.
536 if (spa_version(spa) >= SPA_VERSION_FEATURES)
537 spa_feature_create_zap_objects(spa, tx);
539 if (dcp != NULL && dcp->cp_crypt != ZIO_CRYPT_OFF &&
540 dcp->cp_crypt != ZIO_CRYPT_INHERIT)
541 spa_feature_enable(spa, SPA_FEATURE_ENCRYPTION, tx);
543 /* create the root dataset */
544 obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, dcp, 0, tx);
546 /* create the root objset */
547 VERIFY0(dsl_dataset_hold_obj_flags(dp, obj,
548 DS_HOLD_FLAG_DECRYPT, FTAG, &ds));
549 rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
550 os = dmu_objset_create_impl(dp->dp_spa, ds,
551 dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
552 rrw_exit(&ds->ds_bp_rwlock, FTAG);
554 zfs_create_fs(os, kcred, zplprops, tx);
556 dsl_dataset_rele_flags(ds, DS_HOLD_FLAG_DECRYPT, FTAG);
560 rrw_exit(&dp->dp_config_rwlock, FTAG);
566 * Account for the meta-objset space in its placeholder dsl_dir.
569 dsl_pool_mos_diduse_space(dsl_pool_t *dp,
570 int64_t used, int64_t comp, int64_t uncomp)
572 ASSERT3U(comp, ==, uncomp); /* it's all metadata */
573 mutex_enter(&dp->dp_lock);
574 dp->dp_mos_used_delta += used;
575 dp->dp_mos_compressed_delta += comp;
576 dp->dp_mos_uncompressed_delta += uncomp;
577 mutex_exit(&dp->dp_lock);
581 dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
583 zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
584 dmu_objset_sync(dp->dp_meta_objset, zio, tx);
585 VERIFY0(zio_wait(zio));
586 dmu_objset_sync_done(dp->dp_meta_objset, tx);
587 taskq_wait(dp->dp_sync_taskq);
588 multilist_destroy(&dp->dp_meta_objset->os_synced_dnodes);
590 dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
591 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
595 dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
597 ASSERT(MUTEX_HELD(&dp->dp_lock));
600 ASSERT3U(-delta, <=, dp->dp_dirty_total);
602 dp->dp_dirty_total += delta;
605 * Note: we signal even when increasing dp_dirty_total.
606 * This ensures forward progress -- each thread wakes the next waiter.
608 if (dp->dp_dirty_total < zfs_dirty_data_max)
609 cv_signal(&dp->dp_spaceavail_cv);
613 dsl_pool_wrlog_count(dsl_pool_t *dp, int64_t size, uint64_t txg)
615 ASSERT3S(size, >=, 0);
617 aggsum_add(&dp->dp_wrlog_pertxg[txg & TXG_MASK], size);
618 aggsum_add(&dp->dp_wrlog_total, size);
620 /* Choose a value slightly bigger than min dirty sync bytes */
622 zfs_wrlog_data_max * (zfs_dirty_data_sync_percent + 10) / 200;
623 if (aggsum_compare(&dp->dp_wrlog_pertxg[txg & TXG_MASK], sync_min) > 0)
628 dsl_pool_need_wrlog_delay(dsl_pool_t *dp)
630 uint64_t delay_min_bytes =
631 zfs_wrlog_data_max * zfs_delay_min_dirty_percent / 100;
633 return (aggsum_compare(&dp->dp_wrlog_total, delay_min_bytes) > 0);
637 dsl_pool_wrlog_clear(dsl_pool_t *dp, uint64_t txg)
640 delta = -(int64_t)aggsum_value(&dp->dp_wrlog_pertxg[txg & TXG_MASK]);
641 aggsum_add(&dp->dp_wrlog_pertxg[txg & TXG_MASK], delta);
642 aggsum_add(&dp->dp_wrlog_total, delta);
643 /* Compact per-CPU sums after the big change. */
644 (void) aggsum_value(&dp->dp_wrlog_pertxg[txg & TXG_MASK]);
645 (void) aggsum_value(&dp->dp_wrlog_total);
650 dsl_early_sync_task_verify(dsl_pool_t *dp, uint64_t txg)
652 spa_t *spa = dp->dp_spa;
653 vdev_t *rvd = spa->spa_root_vdev;
655 for (uint64_t c = 0; c < rvd->vdev_children; c++) {
656 vdev_t *vd = rvd->vdev_child[c];
657 txg_list_t *tl = &vd->vdev_ms_list;
660 for (ms = txg_list_head(tl, TXG_CLEAN(txg)); ms;
661 ms = txg_list_next(tl, ms, TXG_CLEAN(txg))) {
662 VERIFY(range_tree_is_empty(ms->ms_freeing));
663 VERIFY(range_tree_is_empty(ms->ms_checkpointing));
670 #define dsl_early_sync_task_verify(dp, txg) \
671 ((void) sizeof (dp), (void) sizeof (txg), B_TRUE)
675 dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
681 objset_t *mos = dp->dp_meta_objset;
682 list_t synced_datasets;
684 list_create(&synced_datasets, sizeof (dsl_dataset_t),
685 offsetof(dsl_dataset_t, ds_synced_link));
687 tx = dmu_tx_create_assigned(dp, txg);
690 * Run all early sync tasks before writing out any dirty blocks.
691 * For more info on early sync tasks see block comment in
692 * dsl_early_sync_task().
694 if (!txg_list_empty(&dp->dp_early_sync_tasks, txg)) {
695 dsl_sync_task_t *dst;
697 ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
699 txg_list_remove(&dp->dp_early_sync_tasks, txg)) != NULL) {
700 ASSERT(dsl_early_sync_task_verify(dp, txg));
701 dsl_sync_task_sync(dst, tx);
703 ASSERT(dsl_early_sync_task_verify(dp, txg));
707 * Write out all dirty blocks of dirty datasets.
709 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
710 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
712 * We must not sync any non-MOS datasets twice, because
713 * we may have taken a snapshot of them. However, we
714 * may sync newly-created datasets on pass 2.
716 ASSERT(!list_link_active(&ds->ds_synced_link));
717 list_insert_tail(&synced_datasets, ds);
718 dsl_dataset_sync(ds, zio, tx);
720 VERIFY0(zio_wait(zio));
723 * Update the long range free counter after
724 * we're done syncing user data
726 mutex_enter(&dp->dp_lock);
727 ASSERT(spa_sync_pass(dp->dp_spa) == 1 ||
728 dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] == 0);
729 dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] = 0;
730 mutex_exit(&dp->dp_lock);
733 * After the data blocks have been written (ensured by the zio_wait()
734 * above), update the user/group/project space accounting. This happens
735 * in tasks dispatched to dp_sync_taskq, so wait for them before
738 for (ds = list_head(&synced_datasets); ds != NULL;
739 ds = list_next(&synced_datasets, ds)) {
740 dmu_objset_sync_done(ds->ds_objset, tx);
742 taskq_wait(dp->dp_sync_taskq);
745 * Sync the datasets again to push out the changes due to
746 * userspace updates. This must be done before we process the
747 * sync tasks, so that any snapshots will have the correct
748 * user accounting information (and we won't get confused
749 * about which blocks are part of the snapshot).
751 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
752 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
753 objset_t *os = ds->ds_objset;
755 ASSERT(list_link_active(&ds->ds_synced_link));
756 dmu_buf_rele(ds->ds_dbuf, ds);
757 dsl_dataset_sync(ds, zio, tx);
760 * Release any key mappings created by calls to
761 * dsl_dataset_dirty() from the userquota accounting
764 if (os->os_encrypted && !os->os_raw_receive &&
765 !os->os_next_write_raw[txg & TXG_MASK]) {
766 ASSERT3P(ds->ds_key_mapping, !=, NULL);
767 key_mapping_rele(dp->dp_spa, ds->ds_key_mapping, ds);
770 VERIFY0(zio_wait(zio));
773 * Now that the datasets have been completely synced, we can
774 * clean up our in-memory structures accumulated while syncing:
776 * - move dead blocks from the pending deadlist and livelists
777 * to the on-disk versions
778 * - release hold from dsl_dataset_dirty()
779 * - release key mapping hold from dsl_dataset_dirty()
781 while ((ds = list_remove_head(&synced_datasets)) != NULL) {
782 objset_t *os = ds->ds_objset;
784 if (os->os_encrypted && !os->os_raw_receive &&
785 !os->os_next_write_raw[txg & TXG_MASK]) {
786 ASSERT3P(ds->ds_key_mapping, !=, NULL);
787 key_mapping_rele(dp->dp_spa, ds->ds_key_mapping, ds);
790 dsl_dataset_sync_done(ds, tx);
791 dmu_buf_rele(ds->ds_dbuf, ds);
794 while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
795 dsl_dir_sync(dd, tx);
799 * The MOS's space is accounted for in the pool/$MOS
800 * (dp_mos_dir). We can't modify the mos while we're syncing
801 * it, so we remember the deltas and apply them here.
803 if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
804 dp->dp_mos_uncompressed_delta != 0) {
805 dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
806 dp->dp_mos_used_delta,
807 dp->dp_mos_compressed_delta,
808 dp->dp_mos_uncompressed_delta, tx);
809 dp->dp_mos_used_delta = 0;
810 dp->dp_mos_compressed_delta = 0;
811 dp->dp_mos_uncompressed_delta = 0;
814 if (dmu_objset_is_dirty(mos, txg)) {
815 dsl_pool_sync_mos(dp, tx);
819 * We have written all of the accounted dirty data, so our
820 * dp_space_towrite should now be zero. However, some seldom-used
821 * code paths do not adhere to this (e.g. dbuf_undirty()). Shore up
822 * the accounting of any dirtied space now.
824 * Note that, besides any dirty data from datasets, the amount of
825 * dirty data in the MOS is also accounted by the pool. Therefore,
826 * we want to do this cleanup after dsl_pool_sync_mos() so we don't
827 * attempt to update the accounting for the same dirty data twice.
828 * (i.e. at this point we only update the accounting for the space
829 * that we know that we "leaked").
831 dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
834 * If we modify a dataset in the same txg that we want to destroy it,
835 * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
836 * dsl_dir_destroy_check() will fail if there are unexpected holds.
837 * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
838 * and clearing the hold on it) before we process the sync_tasks.
839 * The MOS data dirtied by the sync_tasks will be synced on the next
842 if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
843 dsl_sync_task_t *dst;
845 * No more sync tasks should have been added while we
848 ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
849 while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
850 dsl_sync_task_sync(dst, tx);
855 DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
859 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
863 while ((zilog = txg_list_head(&dp->dp_dirty_zilogs, txg))) {
864 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
866 * We don't remove the zilog from the dp_dirty_zilogs
867 * list until after we've cleaned it. This ensures that
868 * callers of zilog_is_dirty() receive an accurate
869 * answer when they are racing with the spa sync thread.
871 zil_clean(zilog, txg);
872 (void) txg_list_remove_this(&dp->dp_dirty_zilogs, zilog, txg);
873 ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
874 dmu_buf_rele(ds->ds_dbuf, zilog);
877 dsl_pool_wrlog_clear(dp, txg);
879 ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
883 * TRUE if the current thread is the tx_sync_thread or if we
884 * are being called from SPA context during pool initialization.
887 dsl_pool_sync_context(dsl_pool_t *dp)
889 return (curthread == dp->dp_tx.tx_sync_thread ||
890 spa_is_initializing(dp->dp_spa) ||
891 taskq_member(dp->dp_sync_taskq, curthread));
895 * This function returns the amount of allocatable space in the pool
896 * minus whatever space is currently reserved by ZFS for specific
897 * purposes. Specifically:
899 * 1] Any reserved SLOP space
900 * 2] Any space used by the checkpoint
901 * 3] Any space used for deferred frees
903 * The latter 2 are especially important because they are needed to
904 * rectify the SPA's and DMU's different understanding of how much space
905 * is used. Now the DMU is aware of that extra space tracked by the SPA
906 * without having to maintain a separate special dir (e.g similar to
907 * $MOS, $FREEING, and $LEAKED).
909 * Note: By deferred frees here, we mean the frees that were deferred
910 * in spa_sync() after sync pass 1 (spa_deferred_bpobj), and not the
911 * segments placed in ms_defer trees during metaslab_sync_done().
914 dsl_pool_adjustedsize(dsl_pool_t *dp, zfs_space_check_t slop_policy)
916 spa_t *spa = dp->dp_spa;
917 uint64_t space, resv, adjustedsize;
918 uint64_t spa_deferred_frees =
919 spa->spa_deferred_bpobj.bpo_phys->bpo_bytes;
921 space = spa_get_dspace(spa)
922 - spa_get_checkpoint_space(spa) - spa_deferred_frees;
923 resv = spa_get_slop_space(spa);
925 switch (slop_policy) {
926 case ZFS_SPACE_CHECK_NORMAL:
928 case ZFS_SPACE_CHECK_RESERVED:
931 case ZFS_SPACE_CHECK_EXTRA_RESERVED:
934 case ZFS_SPACE_CHECK_NONE:
938 panic("invalid slop policy value: %d", slop_policy);
941 adjustedsize = (space >= resv) ? (space - resv) : 0;
943 return (adjustedsize);
947 dsl_pool_unreserved_space(dsl_pool_t *dp, zfs_space_check_t slop_policy)
949 uint64_t poolsize = dsl_pool_adjustedsize(dp, slop_policy);
951 metaslab_class_get_deferred(spa_normal_class(dp->dp_spa));
952 uint64_t quota = (poolsize >= deferred) ? (poolsize - deferred) : 0;
957 dsl_pool_deferred_space(dsl_pool_t *dp)
959 return (metaslab_class_get_deferred(spa_normal_class(dp->dp_spa)));
963 dsl_pool_need_dirty_delay(dsl_pool_t *dp)
965 uint64_t delay_min_bytes =
966 zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
969 * We are not taking the dp_lock here and few other places, since torn
970 * reads are unlikely: on 64-bit systems due to register size and on
971 * 32-bit due to memory constraints. Pool-wide locks in hot path may
972 * be too expensive, while we do not need a precise result here.
974 return (dp->dp_dirty_total > delay_min_bytes);
978 dsl_pool_need_dirty_sync(dsl_pool_t *dp, uint64_t txg)
980 uint64_t dirty_min_bytes =
981 zfs_dirty_data_max * zfs_dirty_data_sync_percent / 100;
982 uint64_t dirty = dp->dp_dirty_pertxg[txg & TXG_MASK];
984 return (dirty > dirty_min_bytes);
988 dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
991 mutex_enter(&dp->dp_lock);
992 dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
993 dsl_pool_dirty_delta(dp, space);
994 boolean_t needsync = !dmu_tx_is_syncing(tx) &&
995 dsl_pool_need_dirty_sync(dp, tx->tx_txg);
996 mutex_exit(&dp->dp_lock);
999 txg_kick(dp, tx->tx_txg);
1004 dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
1006 ASSERT3S(space, >=, 0);
1010 mutex_enter(&dp->dp_lock);
1011 if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
1012 /* XXX writing something we didn't dirty? */
1013 space = dp->dp_dirty_pertxg[txg & TXG_MASK];
1015 ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
1016 dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
1017 ASSERT3U(dp->dp_dirty_total, >=, space);
1018 dsl_pool_dirty_delta(dp, -space);
1019 mutex_exit(&dp->dp_lock);
1023 upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
1026 dsl_dataset_t *ds, *prev = NULL;
1029 err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
1033 while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
1034 err = dsl_dataset_hold_obj(dp,
1035 dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
1037 dsl_dataset_rele(ds, FTAG);
1041 if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object)
1043 dsl_dataset_rele(ds, FTAG);
1049 prev = dp->dp_origin_snap;
1052 * The $ORIGIN can't have any data, or the accounting
1055 rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
1056 ASSERT0(dsl_dataset_phys(prev)->ds_bp.blk_birth);
1057 rrw_exit(&ds->ds_bp_rwlock, FTAG);
1059 /* The origin doesn't get attached to itself */
1060 if (ds->ds_object == prev->ds_object) {
1061 dsl_dataset_rele(ds, FTAG);
1065 dmu_buf_will_dirty(ds->ds_dbuf, tx);
1066 dsl_dataset_phys(ds)->ds_prev_snap_obj = prev->ds_object;
1067 dsl_dataset_phys(ds)->ds_prev_snap_txg =
1068 dsl_dataset_phys(prev)->ds_creation_txg;
1070 dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
1071 dsl_dir_phys(ds->ds_dir)->dd_origin_obj = prev->ds_object;
1073 dmu_buf_will_dirty(prev->ds_dbuf, tx);
1074 dsl_dataset_phys(prev)->ds_num_children++;
1076 if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0) {
1077 ASSERT(ds->ds_prev == NULL);
1078 VERIFY0(dsl_dataset_hold_obj(dp,
1079 dsl_dataset_phys(ds)->ds_prev_snap_obj,
1084 ASSERT3U(dsl_dir_phys(ds->ds_dir)->dd_origin_obj, ==, prev->ds_object);
1085 ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_obj, ==, prev->ds_object);
1087 if (dsl_dataset_phys(prev)->ds_next_clones_obj == 0) {
1088 dmu_buf_will_dirty(prev->ds_dbuf, tx);
1089 dsl_dataset_phys(prev)->ds_next_clones_obj =
1090 zap_create(dp->dp_meta_objset,
1091 DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
1093 VERIFY0(zap_add_int(dp->dp_meta_objset,
1094 dsl_dataset_phys(prev)->ds_next_clones_obj, ds->ds_object, tx));
1096 dsl_dataset_rele(ds, FTAG);
1097 if (prev != dp->dp_origin_snap)
1098 dsl_dataset_rele(prev, FTAG);
1103 dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
1105 ASSERT(dmu_tx_is_syncing(tx));
1106 ASSERT(dp->dp_origin_snap != NULL);
1108 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
1109 tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
1113 upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
1116 objset_t *mos = dp->dp_meta_objset;
1118 if (dsl_dir_phys(ds->ds_dir)->dd_origin_obj != 0) {
1119 dsl_dataset_t *origin;
1121 VERIFY0(dsl_dataset_hold_obj(dp,
1122 dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &origin));
1124 if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) {
1125 dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
1126 dsl_dir_phys(origin->ds_dir)->dd_clones =
1127 zap_create(mos, DMU_OT_DSL_CLONES, DMU_OT_NONE,
1131 VERIFY0(zap_add_int(dp->dp_meta_objset,
1132 dsl_dir_phys(origin->ds_dir)->dd_clones,
1133 ds->ds_object, tx));
1135 dsl_dataset_rele(origin, FTAG);
1141 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
1145 ASSERT(dmu_tx_is_syncing(tx));
1147 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
1148 VERIFY0(dsl_pool_open_special_dir(dp,
1149 FREE_DIR_NAME, &dp->dp_free_dir));
1152 * We can't use bpobj_alloc(), because spa_version() still
1153 * returns the old version, and we need a new-version bpobj with
1154 * subobj support. So call dmu_object_alloc() directly.
1156 obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
1157 SPA_OLD_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
1158 VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
1159 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
1160 VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
1162 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1163 upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
1167 dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
1172 ASSERT(dmu_tx_is_syncing(tx));
1173 ASSERT(dp->dp_origin_snap == NULL);
1174 ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
1176 /* create the origin dir, ds, & snap-ds */
1177 dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
1178 NULL, 0, kcred, NULL, tx);
1179 VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1180 dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
1181 VERIFY0(dsl_dataset_hold_obj(dp, dsl_dataset_phys(ds)->ds_prev_snap_obj,
1182 dp, &dp->dp_origin_snap));
1183 dsl_dataset_rele(ds, FTAG);
1187 dsl_pool_zrele_taskq(dsl_pool_t *dp)
1189 return (dp->dp_zrele_taskq);
1193 dsl_pool_unlinked_drain_taskq(dsl_pool_t *dp)
1195 return (dp->dp_unlinked_drain_taskq);
1199 * Walk through the pool-wide zap object of temporary snapshot user holds
1203 dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
1207 objset_t *mos = dp->dp_meta_objset;
1208 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
1213 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
1215 holds = fnvlist_alloc();
1217 for (zap_cursor_init(&zc, mos, zapobj);
1218 zap_cursor_retrieve(&zc, &za) == 0;
1219 zap_cursor_advance(&zc)) {
1223 htag = strchr(za.za_name, '-');
1226 if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
1227 tags = fnvlist_alloc();
1228 fnvlist_add_boolean(tags, htag);
1229 fnvlist_add_nvlist(holds, za.za_name, tags);
1232 fnvlist_add_boolean(tags, htag);
1235 dsl_dataset_user_release_tmp(dp, holds);
1236 fnvlist_free(holds);
1237 zap_cursor_fini(&zc);
1241 * Create the pool-wide zap object for storing temporary snapshot holds.
1244 dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
1246 objset_t *mos = dp->dp_meta_objset;
1248 ASSERT(dp->dp_tmp_userrefs_obj == 0);
1249 ASSERT(dmu_tx_is_syncing(tx));
1251 dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
1252 DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
1256 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
1257 const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
1259 objset_t *mos = dp->dp_meta_objset;
1260 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
1264 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
1265 ASSERT(dmu_tx_is_syncing(tx));
1268 * If the pool was created prior to SPA_VERSION_USERREFS, the
1269 * zap object for temporary holds might not exist yet.
1273 dsl_pool_user_hold_create_obj(dp, tx);
1274 zapobj = dp->dp_tmp_userrefs_obj;
1276 return (SET_ERROR(ENOENT));
1280 name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
1282 error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
1284 error = zap_remove(mos, zapobj, name, tx);
1291 * Add a temporary hold for the given dataset object and tag.
1294 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
1295 uint64_t now, dmu_tx_t *tx)
1297 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
1301 * Release a temporary hold for the given dataset object and tag.
1304 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
1307 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, 0,
1312 * DSL Pool Configuration Lock
1314 * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
1315 * creation / destruction / rename / property setting). It must be held for
1316 * read to hold a dataset or dsl_dir. I.e. you must call
1317 * dsl_pool_config_enter() or dsl_pool_hold() before calling
1318 * dsl_{dataset,dir}_hold{_obj}. In most circumstances, the dp_config_rwlock
1319 * must be held continuously until all datasets and dsl_dirs are released.
1321 * The only exception to this rule is that if a "long hold" is placed on
1322 * a dataset, then the dp_config_rwlock may be dropped while the dataset
1323 * is still held. The long hold will prevent the dataset from being
1324 * destroyed -- the destroy will fail with EBUSY. A long hold can be
1325 * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
1326 * (by calling dsl_{dataset,objset}_{try}own{_obj}).
1328 * Legitimate long-holders (including owners) should be long-running, cancelable
1329 * tasks that should cause "zfs destroy" to fail. This includes DMU
1330 * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
1331 * "zfs send", and "zfs diff". There are several other long-holders whose
1332 * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
1334 * The usual formula for long-holding would be:
1336 * dsl_dataset_hold()
1337 * ... perform checks ...
1338 * dsl_dataset_long_hold()
1340 * ... perform long-running task ...
1341 * dsl_dataset_long_rele()
1342 * dsl_dataset_rele()
1344 * Note that when the long hold is released, the dataset is still held but
1345 * the pool is not held. The dataset may change arbitrarily during this time
1346 * (e.g. it could be destroyed). Therefore you shouldn't do anything to the
1347 * dataset except release it.
1349 * Operations generally fall somewhere into the following taxonomy:
1351 * Read-Only Modifying
1353 * Dataset Layer / MOS zfs get zfs destroy
1355 * Individual Dataset read() write()
1358 * Dataset Layer Operations
1360 * Modifying operations should generally use dsl_sync_task(). The synctask
1361 * infrastructure enforces proper locking strategy with respect to the
1362 * dp_config_rwlock. See the comment above dsl_sync_task() for details.
1364 * Read-only operations will manually hold the pool, then the dataset, obtain
1365 * information from the dataset, then release the pool and dataset.
1366 * dmu_objset_{hold,rele}() are convenience routines that also do the pool
1370 * Operations On Individual Datasets
1372 * Objects _within_ an objset should only be modified by the current 'owner'
1373 * of the objset to prevent incorrect concurrent modification. Thus, use
1374 * {dmu_objset,dsl_dataset}_own to mark some entity as the current owner,
1375 * and fail with EBUSY if there is already an owner. The owner can then
1376 * implement its own locking strategy, independent of the dataset layer's
1377 * locking infrastructure.
1378 * (E.g., the ZPL has its own set of locks to control concurrency. A regular
1379 * vnop will not reach into the dataset layer).
1381 * Ideally, objects would also only be read by the objset’s owner, so that we
1382 * don’t observe state mid-modification.
1383 * (E.g. the ZPL is creating a new object and linking it into a directory; if
1384 * you don’t coordinate with the ZPL to hold ZPL-level locks, you could see an
1385 * intermediate state. The ioctl level violates this but in pretty benign
1386 * ways, e.g. reading the zpl props object.)
1390 dsl_pool_hold(const char *name, const void *tag, dsl_pool_t **dp)
1395 error = spa_open(name, &spa, tag);
1397 *dp = spa_get_dsl(spa);
1398 dsl_pool_config_enter(*dp, tag);
1404 dsl_pool_rele(dsl_pool_t *dp, const void *tag)
1406 dsl_pool_config_exit(dp, tag);
1407 spa_close(dp->dp_spa, tag);
1411 dsl_pool_config_enter(dsl_pool_t *dp, const void *tag)
1414 * We use a "reentrant" reader-writer lock, but not reentrantly.
1416 * The rrwlock can (with the track_all flag) track all reading threads,
1417 * which is very useful for debugging which code path failed to release
1418 * the lock, and for verifying that the *current* thread does hold
1421 * (Unlike a rwlock, which knows that N threads hold it for
1422 * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
1423 * if any thread holds it for read, even if this thread doesn't).
1425 ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1426 rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
1430 dsl_pool_config_enter_prio(dsl_pool_t *dp, const void *tag)
1432 ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1433 rrw_enter_read_prio(&dp->dp_config_rwlock, tag);
1437 dsl_pool_config_exit(dsl_pool_t *dp, const void *tag)
1439 rrw_exit(&dp->dp_config_rwlock, tag);
1443 dsl_pool_config_held(dsl_pool_t *dp)
1445 return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
1449 dsl_pool_config_held_writer(dsl_pool_t *dp)
1451 return (RRW_WRITE_HELD(&dp->dp_config_rwlock));
1454 EXPORT_SYMBOL(dsl_pool_config_enter);
1455 EXPORT_SYMBOL(dsl_pool_config_exit);
1457 /* zfs_dirty_data_max_percent only applied at module load in arc_init(). */
1458 ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max_percent, UINT, ZMOD_RD,
1459 "Max percent of RAM allowed to be dirty");
1461 /* zfs_dirty_data_max_max_percent only applied at module load in arc_init(). */
1462 ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max_max_percent, UINT, ZMOD_RD,
1463 "zfs_dirty_data_max upper bound as % of RAM");
1465 ZFS_MODULE_PARAM(zfs, zfs_, delay_min_dirty_percent, UINT, ZMOD_RW,
1466 "Transaction delay threshold");
1468 ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max, U64, ZMOD_RW,
1469 "Determines the dirty space limit");
1471 ZFS_MODULE_PARAM(zfs, zfs_, wrlog_data_max, U64, ZMOD_RW,
1472 "The size limit of write-transaction zil log data");
1474 /* zfs_dirty_data_max_max only applied at module load in arc_init(). */
1475 ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max_max, U64, ZMOD_RD,
1476 "zfs_dirty_data_max upper bound in bytes");
1478 ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_sync_percent, UINT, ZMOD_RW,
1479 "Dirty data txg sync threshold as a percentage of zfs_dirty_data_max");
1481 ZFS_MODULE_PARAM(zfs, zfs_, delay_scale, U64, ZMOD_RW,
1482 "How quickly delay approaches infinity");
1484 ZFS_MODULE_PARAM(zfs, zfs_, sync_taskq_batch_pct, INT, ZMOD_RW,
1485 "Max percent of CPUs that are used to sync dirty data");
1487 ZFS_MODULE_PARAM(zfs_zil, zfs_zil_, clean_taskq_nthr_pct, INT, ZMOD_RW,
1488 "Max percent of CPUs that are used per dp_sync_taskq");
1490 ZFS_MODULE_PARAM(zfs_zil, zfs_zil_, clean_taskq_minalloc, INT, ZMOD_RW,
1491 "Number of taskq entries that are pre-populated");
1493 ZFS_MODULE_PARAM(zfs_zil, zfs_zil_, clean_taskq_maxalloc, INT, ZMOD_RW,
1494 "Max number of taskq entries that are cached");