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 http://www.opensolaris.org/os/licensing.
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) 2013 by Delphix. All rights reserved.
24 * Copyright (c) 2013 Steven Hartland. All rights reserved.
27 #include <sys/dsl_pool.h>
28 #include <sys/dsl_dataset.h>
29 #include <sys/dsl_prop.h>
30 #include <sys/dsl_dir.h>
31 #include <sys/dsl_synctask.h>
32 #include <sys/dsl_scan.h>
33 #include <sys/dnode.h>
34 #include <sys/dmu_tx.h>
35 #include <sys/dmu_objset.h>
39 #include <sys/zfs_context.h>
40 #include <sys/fs/zfs.h>
41 #include <sys/zfs_znode.h>
42 #include <sys/spa_impl.h>
43 #include <sys/dsl_deadlist.h>
44 #include <sys/bptree.h>
45 #include <sys/zfeature.h>
46 #include <sys/zil_impl.h>
47 #include <sys/dsl_userhold.h>
53 * ZFS must limit the rate of incoming writes to the rate at which it is able
54 * to sync data modifications to the backend storage. Throttling by too much
55 * creates an artificial limit; throttling by too little can only be sustained
56 * for short periods and would lead to highly lumpy performance. On a per-pool
57 * basis, ZFS tracks the amount of modified (dirty) data. As operations change
58 * data, the amount of dirty data increases; as ZFS syncs out data, the amount
59 * of dirty data decreases. When the amount of dirty data exceeds a
60 * predetermined threshold further modifications are blocked until the amount
61 * of dirty data decreases (as data is synced out).
63 * The limit on dirty data is tunable, and should be adjusted according to
64 * both the IO capacity and available memory of the system. The larger the
65 * window, the more ZFS is able to aggregate and amortize metadata (and data)
66 * changes. However, memory is a limited resource, and allowing for more dirty
67 * data comes at the cost of keeping other useful data in memory (for example
68 * ZFS data cached by the ARC).
72 * As buffers are modified dsl_pool_willuse_space() increments both the per-
73 * txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
74 * dirty space used; dsl_pool_dirty_space() decrements those values as data
75 * is synced out from dsl_pool_sync(). While only the poolwide value is
76 * relevant, the per-txg value is useful for debugging. The tunable
77 * zfs_dirty_data_max determines the dirty space limit. Once that value is
78 * exceeded, new writes are halted until space frees up.
80 * The zfs_dirty_data_sync tunable dictates the threshold at which we
81 * ensure that there is a txg syncing (see the comment in txg.c for a full
82 * description of transaction group stages).
84 * The IO scheduler uses both the dirty space limit and current amount of
85 * dirty data as inputs. Those values affect the number of concurrent IOs ZFS
86 * issues. See the comment in vdev_queue.c for details of the IO scheduler.
88 * The delay is also calculated based on the amount of dirty data. See the
89 * comment above dmu_tx_delay() for details.
93 * zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
94 * capped at zfs_dirty_data_max_max. It can also be overridden with a module
97 unsigned long zfs_dirty_data_max = 0;
98 unsigned long zfs_dirty_data_max_max = 0;
99 int zfs_dirty_data_max_percent = 10;
100 int zfs_dirty_data_max_max_percent = 25;
103 * If there is at least this much dirty data, push out a txg.
105 unsigned long zfs_dirty_data_sync = 64 * 1024 * 1024;
108 * Once there is this amount of dirty data, the dmu_tx_delay() will kick in
109 * and delay each transaction.
110 * This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
112 int zfs_delay_min_dirty_percent = 60;
115 * This controls how quickly the delay approaches infinity.
116 * Larger values cause it to delay more for a given amount of dirty data.
117 * Therefore larger values will cause there to be less dirty data for a
120 * For the smoothest delay, this value should be about 1 billion divided
121 * by the maximum number of operations per second. This will smoothly
122 * handle between 10x and 1/10th this number.
124 * Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
125 * multiply in dmu_tx_delay().
127 unsigned long zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
129 hrtime_t zfs_throttle_delay = MSEC2NSEC(10);
130 hrtime_t zfs_throttle_resolution = MSEC2NSEC(10);
133 dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
138 err = zap_lookup(dp->dp_meta_objset,
139 dp->dp_root_dir->dd_phys->dd_child_dir_zapobj,
140 name, sizeof (obj), 1, &obj);
144 return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
148 dsl_pool_open_impl(spa_t *spa, uint64_t txg)
151 blkptr_t *bp = spa_get_rootblkptr(spa);
153 dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
155 dp->dp_meta_rootbp = *bp;
156 rrw_init(&dp->dp_config_rwlock, B_TRUE);
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));
168 mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
169 cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
171 dp->dp_iput_taskq = taskq_create("zfs_iput_taskq", 1, minclsyspri,
178 dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
181 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
183 err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
184 &dp->dp_meta_objset);
194 dsl_pool_open(dsl_pool_t *dp)
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);
208 err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
209 NULL, dp, &dp->dp_root_dir);
213 err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir);
217 if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
218 err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
221 err = dsl_dataset_hold_obj(dp, dd->dd_phys->dd_head_dataset_obj,
224 err = dsl_dataset_hold_obj(dp,
225 ds->ds_phys->ds_prev_snap_obj, dp,
226 &dp->dp_origin_snap);
227 dsl_dataset_rele(ds, FTAG);
229 dsl_dir_rele(dd, dp);
234 if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
235 err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
240 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
241 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
244 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
245 dp->dp_meta_objset, obj));
248 if (spa_feature_is_active(dp->dp_spa,
249 &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) {
250 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
251 DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
257 if (spa_feature_is_active(dp->dp_spa,
258 &spa_feature_table[SPA_FEATURE_EMPTY_BPOBJ])) {
259 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
260 DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
261 &dp->dp_empty_bpobj);
266 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
267 DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
268 &dp->dp_tmp_userrefs_obj);
274 err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
277 rrw_exit(&dp->dp_config_rwlock, FTAG);
282 dsl_pool_close(dsl_pool_t *dp)
285 * Drop our references from dsl_pool_open().
287 * Since we held the origin_snap from "syncing" context (which
288 * includes pool-opening context), it actually only got a "ref"
289 * and not a hold, so just drop that here.
291 if (dp->dp_origin_snap)
292 dsl_dataset_rele(dp->dp_origin_snap, dp);
294 dsl_dir_rele(dp->dp_mos_dir, dp);
296 dsl_dir_rele(dp->dp_free_dir, dp);
298 dsl_dir_rele(dp->dp_root_dir, dp);
300 bpobj_close(&dp->dp_free_bpobj);
302 /* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
303 if (dp->dp_meta_objset)
304 dmu_objset_evict(dp->dp_meta_objset);
306 txg_list_destroy(&dp->dp_dirty_datasets);
307 txg_list_destroy(&dp->dp_dirty_zilogs);
308 txg_list_destroy(&dp->dp_sync_tasks);
309 txg_list_destroy(&dp->dp_dirty_dirs);
311 arc_flush(dp->dp_spa);
314 rrw_destroy(&dp->dp_config_rwlock);
315 mutex_destroy(&dp->dp_lock);
316 taskq_destroy(dp->dp_iput_taskq);
318 kmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
319 kmem_free(dp, sizeof (dsl_pool_t));
323 dsl_pool_create(spa_t *spa, nvlist_t *zplprops, uint64_t txg)
326 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
327 dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
332 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
334 /* create and open the MOS (meta-objset) */
335 dp->dp_meta_objset = dmu_objset_create_impl(spa,
336 NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
338 /* create the pool directory */
339 err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
340 DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
343 /* Initialize scan structures */
344 VERIFY0(dsl_scan_init(dp, txg));
346 /* create and open the root dir */
347 dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
348 VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
349 NULL, dp, &dp->dp_root_dir));
351 /* create and open the meta-objset dir */
352 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
353 VERIFY0(dsl_pool_open_special_dir(dp,
354 MOS_DIR_NAME, &dp->dp_mos_dir));
356 if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
357 /* create and open the free dir */
358 (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
360 VERIFY0(dsl_pool_open_special_dir(dp,
361 FREE_DIR_NAME, &dp->dp_free_dir));
363 /* create and open the free_bplist */
364 obj = bpobj_alloc(dp->dp_meta_objset, SPA_MAXBLOCKSIZE, tx);
365 VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
366 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
367 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
368 dp->dp_meta_objset, obj));
371 if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
372 dsl_pool_create_origin(dp, tx);
374 /* create the root dataset */
375 obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, 0, tx);
377 /* create the root objset */
378 VERIFY0(dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
379 VERIFY(NULL != (os = dmu_objset_create_impl(dp->dp_spa, ds,
380 dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx)));
382 zfs_create_fs(os, kcred, zplprops, tx);
384 dsl_dataset_rele(ds, FTAG);
388 rrw_exit(&dp->dp_config_rwlock, FTAG);
394 * Account for the meta-objset space in its placeholder dsl_dir.
397 dsl_pool_mos_diduse_space(dsl_pool_t *dp,
398 int64_t used, int64_t comp, int64_t uncomp)
400 ASSERT3U(comp, ==, uncomp); /* it's all metadata */
401 mutex_enter(&dp->dp_lock);
402 dp->dp_mos_used_delta += used;
403 dp->dp_mos_compressed_delta += comp;
404 dp->dp_mos_uncompressed_delta += uncomp;
405 mutex_exit(&dp->dp_lock);
409 deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
411 dsl_deadlist_t *dl = arg;
412 dsl_deadlist_insert(dl, bp, tx);
417 dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
419 zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
420 dmu_objset_sync(dp->dp_meta_objset, zio, tx);
421 VERIFY0(zio_wait(zio));
422 dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
423 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
427 dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
429 ASSERT(MUTEX_HELD(&dp->dp_lock));
432 ASSERT3U(-delta, <=, dp->dp_dirty_total);
434 dp->dp_dirty_total += delta;
437 * Note: we signal even when increasing dp_dirty_total.
438 * This ensures forward progress -- each thread wakes the next waiter.
440 if (dp->dp_dirty_total <= zfs_dirty_data_max)
441 cv_signal(&dp->dp_spaceavail_cv);
445 dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
451 objset_t *mos = dp->dp_meta_objset;
452 list_t synced_datasets;
454 list_create(&synced_datasets, sizeof (dsl_dataset_t),
455 offsetof(dsl_dataset_t, ds_synced_link));
457 tx = dmu_tx_create_assigned(dp, txg);
460 * Write out all dirty blocks of dirty datasets.
462 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
463 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
465 * We must not sync any non-MOS datasets twice, because
466 * we may have taken a snapshot of them. However, we
467 * may sync newly-created datasets on pass 2.
469 ASSERT(!list_link_active(&ds->ds_synced_link));
470 list_insert_tail(&synced_datasets, ds);
471 dsl_dataset_sync(ds, zio, tx);
473 VERIFY0(zio_wait(zio));
476 * We have written all of the accounted dirty data, so our
477 * dp_space_towrite should now be zero. However, some seldom-used
478 * code paths do not adhere to this (e.g. dbuf_undirty(), also
479 * rounding error in dbuf_write_physdone).
480 * Shore up the accounting of any dirtied space now.
482 dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
485 * After the data blocks have been written (ensured by the zio_wait()
486 * above), update the user/group space accounting.
488 for (ds = list_head(&synced_datasets); ds != NULL;
489 ds = list_next(&synced_datasets, ds)) {
490 dmu_objset_do_userquota_updates(ds->ds_objset, tx);
494 * Sync the datasets again to push out the changes due to
495 * userspace updates. This must be done before we process the
496 * sync tasks, so that any snapshots will have the correct
497 * user accounting information (and we won't get confused
498 * about which blocks are part of the snapshot).
500 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
501 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
502 ASSERT(list_link_active(&ds->ds_synced_link));
503 dmu_buf_rele(ds->ds_dbuf, ds);
504 dsl_dataset_sync(ds, zio, tx);
506 VERIFY0(zio_wait(zio));
509 * Now that the datasets have been completely synced, we can
510 * clean up our in-memory structures accumulated while syncing:
512 * - move dead blocks from the pending deadlist to the on-disk deadlist
513 * - release hold from dsl_dataset_dirty()
515 while ((ds = list_remove_head(&synced_datasets)) != NULL) {
516 ASSERTV(objset_t *os = ds->ds_objset);
517 bplist_iterate(&ds->ds_pending_deadlist,
518 deadlist_enqueue_cb, &ds->ds_deadlist, tx);
519 ASSERT(!dmu_objset_is_dirty(os, txg));
520 dmu_buf_rele(ds->ds_dbuf, ds);
523 while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
524 dsl_dir_sync(dd, tx);
528 * The MOS's space is accounted for in the pool/$MOS
529 * (dp_mos_dir). We can't modify the mos while we're syncing
530 * it, so we remember the deltas and apply them here.
532 if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
533 dp->dp_mos_uncompressed_delta != 0) {
534 dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
535 dp->dp_mos_used_delta,
536 dp->dp_mos_compressed_delta,
537 dp->dp_mos_uncompressed_delta, tx);
538 dp->dp_mos_used_delta = 0;
539 dp->dp_mos_compressed_delta = 0;
540 dp->dp_mos_uncompressed_delta = 0;
543 if (list_head(&mos->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
544 list_head(&mos->os_free_dnodes[txg & TXG_MASK]) != NULL) {
545 dsl_pool_sync_mos(dp, tx);
549 * If we modify a dataset in the same txg that we want to destroy it,
550 * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
551 * dsl_dir_destroy_check() will fail if there are unexpected holds.
552 * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
553 * and clearing the hold on it) before we process the sync_tasks.
554 * The MOS data dirtied by the sync_tasks will be synced on the next
557 if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
558 dsl_sync_task_t *dst;
560 * No more sync tasks should have been added while we
563 ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
564 while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
565 dsl_sync_task_sync(dst, tx);
570 DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
574 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
578 while ((zilog = txg_list_remove(&dp->dp_dirty_zilogs, txg))) {
579 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
580 zil_clean(zilog, txg);
581 ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
582 dmu_buf_rele(ds->ds_dbuf, zilog);
584 ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
588 * TRUE if the current thread is the tx_sync_thread or if we
589 * are being called from SPA context during pool initialization.
592 dsl_pool_sync_context(dsl_pool_t *dp)
594 return (curthread == dp->dp_tx.tx_sync_thread ||
595 spa_is_initializing(dp->dp_spa));
599 dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
601 uint64_t space, resv;
604 * Reserve about 1.6% (1/64), or at least 32MB, for allocation
606 * XXX The intent log is not accounted for, so it must fit
609 * If we're trying to assess whether it's OK to do a free,
610 * cut the reservation in half to allow forward progress
611 * (e.g. make it possible to rm(1) files from a full pool).
613 space = spa_get_dspace(dp->dp_spa);
614 resv = MAX(space >> 6, SPA_MINDEVSIZE >> 1);
618 return (space - resv);
622 dsl_pool_need_dirty_delay(dsl_pool_t *dp)
624 uint64_t delay_min_bytes =
625 zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
628 mutex_enter(&dp->dp_lock);
629 if (dp->dp_dirty_total > zfs_dirty_data_sync)
631 rv = (dp->dp_dirty_total > delay_min_bytes);
632 mutex_exit(&dp->dp_lock);
637 dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
640 mutex_enter(&dp->dp_lock);
641 dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
642 dsl_pool_dirty_delta(dp, space);
643 mutex_exit(&dp->dp_lock);
648 dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
650 ASSERT3S(space, >=, 0);
654 mutex_enter(&dp->dp_lock);
655 if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
656 /* XXX writing something we didn't dirty? */
657 space = dp->dp_dirty_pertxg[txg & TXG_MASK];
659 ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
660 dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
661 ASSERT3U(dp->dp_dirty_total, >=, space);
662 dsl_pool_dirty_delta(dp, -space);
663 mutex_exit(&dp->dp_lock);
668 upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
671 dsl_dataset_t *ds, *prev = NULL;
674 err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
678 while (ds->ds_phys->ds_prev_snap_obj != 0) {
679 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
682 dsl_dataset_rele(ds, FTAG);
686 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object)
688 dsl_dataset_rele(ds, FTAG);
694 prev = dp->dp_origin_snap;
697 * The $ORIGIN can't have any data, or the accounting
700 ASSERT0(prev->ds_phys->ds_bp.blk_birth);
702 /* The origin doesn't get attached to itself */
703 if (ds->ds_object == prev->ds_object) {
704 dsl_dataset_rele(ds, FTAG);
708 dmu_buf_will_dirty(ds->ds_dbuf, tx);
709 ds->ds_phys->ds_prev_snap_obj = prev->ds_object;
710 ds->ds_phys->ds_prev_snap_txg = prev->ds_phys->ds_creation_txg;
712 dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
713 ds->ds_dir->dd_phys->dd_origin_obj = prev->ds_object;
715 dmu_buf_will_dirty(prev->ds_dbuf, tx);
716 prev->ds_phys->ds_num_children++;
718 if (ds->ds_phys->ds_next_snap_obj == 0) {
719 ASSERT(ds->ds_prev == NULL);
720 VERIFY0(dsl_dataset_hold_obj(dp,
721 ds->ds_phys->ds_prev_snap_obj, ds, &ds->ds_prev));
725 ASSERT3U(ds->ds_dir->dd_phys->dd_origin_obj, ==, prev->ds_object);
726 ASSERT3U(ds->ds_phys->ds_prev_snap_obj, ==, prev->ds_object);
728 if (prev->ds_phys->ds_next_clones_obj == 0) {
729 dmu_buf_will_dirty(prev->ds_dbuf, tx);
730 prev->ds_phys->ds_next_clones_obj =
731 zap_create(dp->dp_meta_objset,
732 DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
734 VERIFY0(zap_add_int(dp->dp_meta_objset,
735 prev->ds_phys->ds_next_clones_obj, ds->ds_object, tx));
737 dsl_dataset_rele(ds, FTAG);
738 if (prev != dp->dp_origin_snap)
739 dsl_dataset_rele(prev, FTAG);
744 dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
746 ASSERT(dmu_tx_is_syncing(tx));
747 ASSERT(dp->dp_origin_snap != NULL);
749 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
750 tx, DS_FIND_CHILDREN));
755 upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
758 objset_t *mos = dp->dp_meta_objset;
760 if (ds->ds_dir->dd_phys->dd_origin_obj != 0) {
761 dsl_dataset_t *origin;
763 VERIFY0(dsl_dataset_hold_obj(dp,
764 ds->ds_dir->dd_phys->dd_origin_obj, FTAG, &origin));
766 if (origin->ds_dir->dd_phys->dd_clones == 0) {
767 dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
768 origin->ds_dir->dd_phys->dd_clones = zap_create(mos,
769 DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
772 VERIFY0(zap_add_int(dp->dp_meta_objset,
773 origin->ds_dir->dd_phys->dd_clones, ds->ds_object, tx));
775 dsl_dataset_rele(origin, FTAG);
781 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
785 ASSERT(dmu_tx_is_syncing(tx));
787 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
788 VERIFY0(dsl_pool_open_special_dir(dp,
789 FREE_DIR_NAME, &dp->dp_free_dir));
792 * We can't use bpobj_alloc(), because spa_version() still
793 * returns the old version, and we need a new-version bpobj with
794 * subobj support. So call dmu_object_alloc() directly.
796 obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
797 SPA_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
798 VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
799 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
800 VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
802 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
803 upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN));
807 dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
812 ASSERT(dmu_tx_is_syncing(tx));
813 ASSERT(dp->dp_origin_snap == NULL);
814 ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
816 /* create the origin dir, ds, & snap-ds */
817 dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
819 VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
820 dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
821 VERIFY0(dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
822 dp, &dp->dp_origin_snap));
823 dsl_dataset_rele(ds, FTAG);
827 dsl_pool_iput_taskq(dsl_pool_t *dp)
829 return (dp->dp_iput_taskq);
833 * Walk through the pool-wide zap object of temporary snapshot user holds
837 dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
841 objset_t *mos = dp->dp_meta_objset;
842 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
847 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
849 holds = fnvlist_alloc();
851 for (zap_cursor_init(&zc, mos, zapobj);
852 zap_cursor_retrieve(&zc, &za) == 0;
853 zap_cursor_advance(&zc)) {
857 htag = strchr(za.za_name, '-');
860 if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
861 tags = fnvlist_alloc();
862 fnvlist_add_boolean(tags, htag);
863 fnvlist_add_nvlist(holds, za.za_name, tags);
866 fnvlist_add_boolean(tags, htag);
869 dsl_dataset_user_release_tmp(dp, holds);
871 zap_cursor_fini(&zc);
875 * Create the pool-wide zap object for storing temporary snapshot holds.
878 dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
880 objset_t *mos = dp->dp_meta_objset;
882 ASSERT(dp->dp_tmp_userrefs_obj == 0);
883 ASSERT(dmu_tx_is_syncing(tx));
885 dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
886 DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
890 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
891 const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
893 objset_t *mos = dp->dp_meta_objset;
894 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
898 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
899 ASSERT(dmu_tx_is_syncing(tx));
902 * If the pool was created prior to SPA_VERSION_USERREFS, the
903 * zap object for temporary holds might not exist yet.
907 dsl_pool_user_hold_create_obj(dp, tx);
908 zapobj = dp->dp_tmp_userrefs_obj;
910 return (SET_ERROR(ENOENT));
914 name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
916 error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
918 error = zap_remove(mos, zapobj, name, tx);
925 * Add a temporary hold for the given dataset object and tag.
928 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
929 uint64_t now, dmu_tx_t *tx)
931 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
935 * Release a temporary hold for the given dataset object and tag.
938 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
941 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, 0,
946 * DSL Pool Configuration Lock
948 * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
949 * creation / destruction / rename / property setting). It must be held for
950 * read to hold a dataset or dsl_dir. I.e. you must call
951 * dsl_pool_config_enter() or dsl_pool_hold() before calling
952 * dsl_{dataset,dir}_hold{_obj}. In most circumstances, the dp_config_rwlock
953 * must be held continuously until all datasets and dsl_dirs are released.
955 * The only exception to this rule is that if a "long hold" is placed on
956 * a dataset, then the dp_config_rwlock may be dropped while the dataset
957 * is still held. The long hold will prevent the dataset from being
958 * destroyed -- the destroy will fail with EBUSY. A long hold can be
959 * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
960 * (by calling dsl_{dataset,objset}_{try}own{_obj}).
962 * Legitimate long-holders (including owners) should be long-running, cancelable
963 * tasks that should cause "zfs destroy" to fail. This includes DMU
964 * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
965 * "zfs send", and "zfs diff". There are several other long-holders whose
966 * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
968 * The usual formula for long-holding would be:
971 * ... perform checks ...
972 * dsl_dataset_long_hold()
974 * ... perform long-running task ...
975 * dsl_dataset_long_rele()
978 * Note that when the long hold is released, the dataset is still held but
979 * the pool is not held. The dataset may change arbitrarily during this time
980 * (e.g. it could be destroyed). Therefore you shouldn't do anything to the
981 * dataset except release it.
983 * User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
984 * or modifying operations.
986 * Modifying operations should generally use dsl_sync_task(). The synctask
987 * infrastructure enforces proper locking strategy with respect to the
988 * dp_config_rwlock. See the comment above dsl_sync_task() for details.
990 * Read-only operations will manually hold the pool, then the dataset, obtain
991 * information from the dataset, then release the pool and dataset.
992 * dmu_objset_{hold,rele}() are convenience routines that also do the pool
997 dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
1002 error = spa_open(name, &spa, tag);
1004 *dp = spa_get_dsl(spa);
1005 dsl_pool_config_enter(*dp, tag);
1011 dsl_pool_rele(dsl_pool_t *dp, void *tag)
1013 dsl_pool_config_exit(dp, tag);
1014 spa_close(dp->dp_spa, tag);
1018 dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
1021 * We use a "reentrant" reader-writer lock, but not reentrantly.
1023 * The rrwlock can (with the track_all flag) track all reading threads,
1024 * which is very useful for debugging which code path failed to release
1025 * the lock, and for verifying that the *current* thread does hold
1028 * (Unlike a rwlock, which knows that N threads hold it for
1029 * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
1030 * if any thread holds it for read, even if this thread doesn't).
1032 ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1033 rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
1037 dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
1039 rrw_exit(&dp->dp_config_rwlock, tag);
1043 dsl_pool_config_held(dsl_pool_t *dp)
1045 return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
1048 #if defined(_KERNEL) && defined(HAVE_SPL)
1049 EXPORT_SYMBOL(dsl_pool_config_enter);
1050 EXPORT_SYMBOL(dsl_pool_config_exit);
1052 /* zfs_dirty_data_max_percent only applied at module load in arc_init(). */
1053 module_param(zfs_dirty_data_max_percent, int, 0444);
1054 MODULE_PARM_DESC(zfs_dirty_data_max_percent, "percent of ram can be dirty");
1056 /* zfs_dirty_data_max_max_percent only applied at module load in arc_init(). */
1057 module_param(zfs_dirty_data_max_max_percent, int, 0444);
1058 MODULE_PARM_DESC(zfs_dirty_data_max_max_percent,
1059 "zfs_dirty_data_max upper bound as % of RAM");
1061 module_param(zfs_delay_min_dirty_percent, int, 0644);
1062 MODULE_PARM_DESC(zfs_delay_min_dirty_percent, "transaction delay threshold");
1064 module_param(zfs_dirty_data_max, ulong, 0644);
1065 MODULE_PARM_DESC(zfs_dirty_data_max, "determines the dirty space limit");
1067 /* zfs_dirty_data_max_max only applied at module load in arc_init(). */
1068 module_param(zfs_dirty_data_max_max, ulong, 0444);
1069 MODULE_PARM_DESC(zfs_dirty_data_max_max,
1070 "zfs_dirty_data_max upper bound in bytes");
1072 module_param(zfs_dirty_data_sync, ulong, 0644);
1073 MODULE_PARM_DESC(zfs_dirty_data_sync, "sync txg when this much dirty data");
1075 module_param(zfs_delay_scale, ulong, 0644);
1076 MODULE_PARM_DESC(zfs_delay_scale, "how quickly delay approaches infinity");