1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
24 * Copyright (c) 2013 Steven Hartland. All rights reserved.
25 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
26 */
27
28 #include <sys/dsl_pool.h>
29 #include <sys/dsl_dataset.h>
30 #include <sys/dsl_prop.h>
31 #include <sys/dsl_dir.h>
32 #include <sys/dsl_synctask.h>
33 #include <sys/dsl_scan.h>
34 #include <sys/dnode.h>
35 #include <sys/dmu_tx.h>
36 #include <sys/dmu_objset.h>
37 #include <sys/arc.h>
38 #include <sys/zap.h>
39 #include <sys/zio.h>
40 #include <sys/zfs_context.h>
41 #include <sys/fs/zfs.h>
42 #include <sys/zfs_znode.h>
43 #include <sys/spa_impl.h>
44 #include <sys/dsl_deadlist.h>
45 #include <sys/bptree.h>
46 #include <sys/zfeature.h>
47 #include <sys/zil_impl.h>
48 #include <sys/dsl_userhold.h>
49
50 /*
51 * ZFS Write Throttle
52 * ------------------
53 *
54 * ZFS must limit the rate of incoming writes to the rate at which it is able
55 * to sync data modifications to the backend storage. Throttling by too much
56 * creates an artificial limit; throttling by too little can only be sustained
57 * for short periods and would lead to highly lumpy performance. On a per-pool
58 * basis, ZFS tracks the amount of modified (dirty) data. As operations change
59 * data, the amount of dirty data increases; as ZFS syncs out data, the amount
60 * of dirty data decreases. When the amount of dirty data exceeds a
61 * predetermined threshold further modifications are blocked until the amount
62 * of dirty data decreases (as data is synced out).
63 *
64 * The limit on dirty data is tunable, and should be adjusted according to
65 * both the IO capacity and available memory of the system. The larger the
66 * window, the more ZFS is able to aggregate and amortize metadata (and data)
67 * changes. However, memory is a limited resource, and allowing for more dirty
68 * data comes at the cost of keeping other useful data in memory (for example
69 * ZFS data cached by the ARC).
70 *
71 * Implementation
72 *
73 * As buffers are modified dsl_pool_willuse_space() increments both the per-
74 * txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
75 * dirty space used; dsl_pool_dirty_space() decrements those values as data
76 * is synced out from dsl_pool_sync(). While only the poolwide value is
77 * relevant, the per-txg value is useful for debugging. The tunable
78 * zfs_dirty_data_max determines the dirty space limit. Once that value is
79 * exceeded, new writes are halted until space frees up.
80 *
81 * The zfs_dirty_data_sync tunable dictates the threshold at which we
82 * ensure that there is a txg syncing (see the comment in txg.c for a full
83 * description of transaction group stages).
84 *
85 * The IO scheduler uses both the dirty space limit and current amount of
86 * dirty data as inputs. Those values affect the number of concurrent IOs ZFS
87 * issues. See the comment in vdev_queue.c for details of the IO scheduler.
88 *
89 * The delay is also calculated based on the amount of dirty data. See the
90 * comment above dmu_tx_delay() for details.
91 */
92
93 /*
94 * zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
95 * capped at zfs_dirty_data_max_max. It can also be overridden in /etc/system.
96 */
97 uint64_t zfs_dirty_data_max;
98 uint64_t zfs_dirty_data_max_max = 4ULL * 1024 * 1024 * 1024;
99 int zfs_dirty_data_max_percent = 10;
100
101 /*
102 * If there is at least this much dirty data, push out a txg.
103 */
104 uint64_t zfs_dirty_data_sync = 64 * 1024 * 1024;
105
106 /*
107 * Once there is this amount of dirty data, the dmu_tx_delay() will kick in
108 * and delay each transaction.
109 * This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
110 */
111 int zfs_delay_min_dirty_percent = 60;
112
113 /*
114 * This controls how quickly the delay approaches infinity.
115 * Larger values cause it to delay more for a given amount of dirty data.
116 * Therefore larger values will cause there to be less dirty data for a
117 * given throughput.
118 *
119 * For the smoothest delay, this value should be about 1 billion divided
120 * by the maximum number of operations per second. This will smoothly
121 * handle between 10x and 1/10th this number.
122 *
123 * Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
124 * multiply in dmu_tx_delay().
125 */
126 uint64_t zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
127
128
129 hrtime_t zfs_throttle_delay = MSEC2NSEC(10);
130 hrtime_t zfs_throttle_resolution = MSEC2NSEC(10);
131
132 int
133 dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
134 {
135 uint64_t obj;
136 int err;
137
138 err = zap_lookup(dp->dp_meta_objset,
139 dsl_dir_phys(dp->dp_root_dir)->dd_child_dir_zapobj,
140 name, sizeof (obj), 1, &obj);
141 if (err)
142 return (err);
143
144 return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
145 }
146
147 static dsl_pool_t *
148 dsl_pool_open_impl(spa_t *spa, uint64_t txg)
149 {
150 dsl_pool_t *dp;
151 blkptr_t *bp = spa_get_rootblkptr(spa);
152
153 dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
154 dp->dp_spa = spa;
155 dp->dp_meta_rootbp = *bp;
156 rrw_init(&dp->dp_config_rwlock, B_TRUE);
157 txg_init(dp, txg);
158
159 txg_list_create(&dp->dp_dirty_datasets,
160 offsetof(dsl_dataset_t, ds_dirty_link));
161 txg_list_create(&dp->dp_dirty_zilogs,
162 offsetof(zilog_t, zl_dirty_link));
163 txg_list_create(&dp->dp_dirty_dirs,
164 offsetof(dsl_dir_t, dd_dirty_link));
165 txg_list_create(&dp->dp_sync_tasks,
166 offsetof(dsl_sync_task_t, dst_node));
167
168 mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
169 cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
170
171 dp->dp_vnrele_taskq = taskq_create("zfs_vn_rele_taskq", 1, minclsyspri,
172 1, 4, 0);
173
174 return (dp);
175 }
176
177 int
178 dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
179 {
180 int err;
181 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
182
183 err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
184 &dp->dp_meta_objset);
185 if (err != 0)
186 dsl_pool_close(dp);
187 else
188 *dpp = dp;
189
190 return (err);
191 }
192
193 int
194 dsl_pool_open(dsl_pool_t *dp)
195 {
196 int err;
197 dsl_dir_t *dd;
198 dsl_dataset_t *ds;
199 uint64_t obj;
200
201 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
202 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
203 DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1,
204 &dp->dp_root_dir_obj);
205 if (err)
206 goto out;
207
208 err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
209 NULL, dp, &dp->dp_root_dir);
210 if (err)
211 goto out;
212
213 err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir);
214 if (err)
215 goto out;
216
217 if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
218 err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
219 if (err)
220 goto out;
221 err = dsl_dataset_hold_obj(dp,
222 dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds);
223 if (err == 0) {
224 err = dsl_dataset_hold_obj(dp,
225 dsl_dataset_phys(ds)->ds_prev_snap_obj, dp,
226 &dp->dp_origin_snap);
227 dsl_dataset_rele(ds, FTAG);
228 }
229 dsl_dir_rele(dd, dp);
230 if (err)
231 goto out;
232 }
233
234 if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
235 err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
236 &dp->dp_free_dir);
237 if (err)
238 goto out;
239
240 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
241 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
242 if (err)
243 goto out;
244 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
245 dp->dp_meta_objset, obj));
246 }
247
248 /*
249 * Note: errors ignored, because the leak dir will not exist if we
250 * have not encountered a leak yet.
251 */
252 (void) dsl_pool_open_special_dir(dp, LEAK_DIR_NAME,
253 &dp->dp_leak_dir);
254
255 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
256 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
257 DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
258 &dp->dp_bptree_obj);
259 if (err != 0)
260 goto out;
261 }
262
263 if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_EMPTY_BPOBJ)) {
264 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
265 DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
266 &dp->dp_empty_bpobj);
267 if (err != 0)
268 goto out;
269 }
270
271 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
272 DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
273 &dp->dp_tmp_userrefs_obj);
274 if (err == ENOENT)
275 err = 0;
276 if (err)
277 goto out;
278
279 err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
280
281 out:
282 rrw_exit(&dp->dp_config_rwlock, FTAG);
283 return (err);
284 }
285
286 void
287 dsl_pool_close(dsl_pool_t *dp)
288 {
289 /*
290 * Drop our references from dsl_pool_open().
291 *
292 * Since we held the origin_snap from "syncing" context (which
293 * includes pool-opening context), it actually only got a "ref"
294 * and not a hold, so just drop that here.
295 */
296 if (dp->dp_origin_snap)
297 dsl_dataset_rele(dp->dp_origin_snap, dp);
298 if (dp->dp_mos_dir)
299 dsl_dir_rele(dp->dp_mos_dir, dp);
300 if (dp->dp_free_dir)
301 dsl_dir_rele(dp->dp_free_dir, dp);
302 if (dp->dp_leak_dir)
303 dsl_dir_rele(dp->dp_leak_dir, dp);
304 if (dp->dp_root_dir)
305 dsl_dir_rele(dp->dp_root_dir, dp);
306
307 bpobj_close(&dp->dp_free_bpobj);
308
309 /* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
310 if (dp->dp_meta_objset)
311 dmu_objset_evict(dp->dp_meta_objset);
312
313 txg_list_destroy(&dp->dp_dirty_datasets);
314 txg_list_destroy(&dp->dp_dirty_zilogs);
315 txg_list_destroy(&dp->dp_sync_tasks);
316 txg_list_destroy(&dp->dp_dirty_dirs);
317
318 /*
319 * We can't set retry to TRUE since we're explicitly specifying
320 * a spa to flush. This is good enough; any missed buffers for
321 * this spa won't cause trouble, and they'll eventually fall
322 * out of the ARC just like any other unused buffer.
323 */
324 arc_flush(dp->dp_spa, FALSE);
325
326 txg_fini(dp);
327 dsl_scan_fini(dp);
328 dmu_buf_user_evict_wait();
329
330 rrw_destroy(&dp->dp_config_rwlock);
331 mutex_destroy(&dp->dp_lock);
332 taskq_destroy(dp->dp_vnrele_taskq);
333 if (dp->dp_blkstats)
334 kmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
335 kmem_free(dp, sizeof (dsl_pool_t));
336 }
337
338 dsl_pool_t *
339 dsl_pool_create(spa_t *spa, nvlist_t *zplprops, uint64_t txg)
340 {
341 int err;
342 dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
343 dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
344 objset_t *os;
345 dsl_dataset_t *ds;
346 uint64_t obj;
347
348 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
349
350 /* create and open the MOS (meta-objset) */
351 dp->dp_meta_objset = dmu_objset_create_impl(spa,
352 NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
353
354 /* create the pool directory */
355 err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
356 DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
357 ASSERT0(err);
358
359 /* Initialize scan structures */
360 VERIFY0(dsl_scan_init(dp, txg));
361
362 /* create and open the root dir */
363 dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
364 VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
365 NULL, dp, &dp->dp_root_dir));
366
367 /* create and open the meta-objset dir */
368 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
369 VERIFY0(dsl_pool_open_special_dir(dp,
370 MOS_DIR_NAME, &dp->dp_mos_dir));
371
372 if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
373 /* create and open the free dir */
374 (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
375 FREE_DIR_NAME, tx);
376 VERIFY0(dsl_pool_open_special_dir(dp,
377 FREE_DIR_NAME, &dp->dp_free_dir));
378
379 /* create and open the free_bplist */
380 obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
381 VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
382 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
383 VERIFY0(bpobj_open(&dp->dp_free_bpobj,
384 dp->dp_meta_objset, obj));
385 }
386
387 if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
388 dsl_pool_create_origin(dp, tx);
389
390 /* create the root dataset */
391 obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, 0, tx);
392
393 /* create the root objset */
394 VERIFY0(dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
395 os = dmu_objset_create_impl(dp->dp_spa, ds,
396 dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
397 #ifdef _KERNEL
398 zfs_create_fs(os, kcred, zplprops, tx);
399 #endif
400 dsl_dataset_rele(ds, FTAG);
401
402 dmu_tx_commit(tx);
403
404 rrw_exit(&dp->dp_config_rwlock, FTAG);
405
406 return (dp);
407 }
408
409 /*
410 * Account for the meta-objset space in its placeholder dsl_dir.
411 */
412 void
413 dsl_pool_mos_diduse_space(dsl_pool_t *dp,
414 int64_t used, int64_t comp, int64_t uncomp)
415 {
416 ASSERT3U(comp, ==, uncomp); /* it's all metadata */
417 mutex_enter(&dp->dp_lock);
418 dp->dp_mos_used_delta += used;
419 dp->dp_mos_compressed_delta += comp;
420 dp->dp_mos_uncompressed_delta += uncomp;
421 mutex_exit(&dp->dp_lock);
422 }
423
424 static int
425 deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
426 {
427 dsl_deadlist_t *dl = arg;
428 dsl_deadlist_insert(dl, bp, tx);
429 return (0);
430 }
431
432 static void
433 dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
434 {
435 zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
436 dmu_objset_sync(dp->dp_meta_objset, zio, tx);
437 VERIFY0(zio_wait(zio));
438 dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
439 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
440 }
441
442 static void
443 dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
444 {
445 ASSERT(MUTEX_HELD(&dp->dp_lock));
446
447 if (delta < 0)
448 ASSERT3U(-delta, <=, dp->dp_dirty_total);
449
450 dp->dp_dirty_total += delta;
451
452 /*
453 * Note: we signal even when increasing dp_dirty_total.
454 * This ensures forward progress -- each thread wakes the next waiter.
455 */
456 if (dp->dp_dirty_total <= zfs_dirty_data_max)
457 cv_signal(&dp->dp_spaceavail_cv);
458 }
459
460 void
461 dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
462 {
463 zio_t *zio;
464 dmu_tx_t *tx;
465 dsl_dir_t *dd;
466 dsl_dataset_t *ds;
467 objset_t *mos = dp->dp_meta_objset;
468 list_t synced_datasets;
469
470 list_create(&synced_datasets, sizeof (dsl_dataset_t),
471 offsetof(dsl_dataset_t, ds_synced_link));
472
473 tx = dmu_tx_create_assigned(dp, txg);
474
475 /*
476 * Write out all dirty blocks of dirty datasets.
477 */
478 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
479 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
480 /*
481 * We must not sync any non-MOS datasets twice, because
482 * we may have taken a snapshot of them. However, we
483 * may sync newly-created datasets on pass 2.
484 */
485 ASSERT(!list_link_active(&ds->ds_synced_link));
486 list_insert_tail(&synced_datasets, ds);
487 dsl_dataset_sync(ds, zio, tx);
488 }
489 VERIFY0(zio_wait(zio));
490
491 /*
492 * We have written all of the accounted dirty data, so our
493 * dp_space_towrite should now be zero. However, some seldom-used
494 * code paths do not adhere to this (e.g. dbuf_undirty(), also
495 * rounding error in dbuf_write_physdone).
496 * Shore up the accounting of any dirtied space now.
497 */
498 dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
499
500 /*
501 * After the data blocks have been written (ensured by the zio_wait()
502 * above), update the user/group space accounting.
503 */
504 for (ds = list_head(&synced_datasets); ds != NULL;
505 ds = list_next(&synced_datasets, ds)) {
506 dmu_objset_do_userquota_updates(ds->ds_objset, tx);
507 }
508
509 /*
510 * Sync the datasets again to push out the changes due to
511 * userspace updates. This must be done before we process the
512 * sync tasks, so that any snapshots will have the correct
513 * user accounting information (and we won't get confused
514 * about which blocks are part of the snapshot).
515 */
516 zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
517 while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
518 ASSERT(list_link_active(&ds->ds_synced_link));
519 dmu_buf_rele(ds->ds_dbuf, ds);
520 dsl_dataset_sync(ds, zio, tx);
521 }
522 VERIFY0(zio_wait(zio));
523
524 /*
525 * Now that the datasets have been completely synced, we can
526 * clean up our in-memory structures accumulated while syncing:
527 *
528 * - move dead blocks from the pending deadlist to the on-disk deadlist
529 * - release hold from dsl_dataset_dirty()
530 */
531 while ((ds = list_remove_head(&synced_datasets)) != NULL) {
532 objset_t *os = ds->ds_objset;
533 bplist_iterate(&ds->ds_pending_deadlist,
534 deadlist_enqueue_cb, &ds->ds_deadlist, tx);
535 ASSERT(!dmu_objset_is_dirty(os, txg));
536 dmu_buf_rele(ds->ds_dbuf, ds);
537 }
538 while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
539 dsl_dir_sync(dd, tx);
540 }
541
542 /*
543 * The MOS's space is accounted for in the pool/$MOS
544 * (dp_mos_dir). We can't modify the mos while we're syncing
545 * it, so we remember the deltas and apply them here.
546 */
547 if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
548 dp->dp_mos_uncompressed_delta != 0) {
549 dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
550 dp->dp_mos_used_delta,
551 dp->dp_mos_compressed_delta,
552 dp->dp_mos_uncompressed_delta, tx);
553 dp->dp_mos_used_delta = 0;
554 dp->dp_mos_compressed_delta = 0;
555 dp->dp_mos_uncompressed_delta = 0;
556 }
557
558 if (list_head(&mos->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
559 list_head(&mos->os_free_dnodes[txg & TXG_MASK]) != NULL) {
560 dsl_pool_sync_mos(dp, tx);
561 }
562
563 /*
564 * If we modify a dataset in the same txg that we want to destroy it,
565 * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
566 * dsl_dir_destroy_check() will fail if there are unexpected holds.
567 * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
568 * and clearing the hold on it) before we process the sync_tasks.
569 * The MOS data dirtied by the sync_tasks will be synced on the next
570 * pass.
571 */
572 if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
573 dsl_sync_task_t *dst;
574 /*
575 * No more sync tasks should have been added while we
576 * were syncing.
577 */
578 ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
579 while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
580 dsl_sync_task_sync(dst, tx);
581 }
582
583 dmu_tx_commit(tx);
584
585 DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
586 }
587
588 void
589 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
590 {
591 zilog_t *zilog;
592
593 while (zilog = txg_list_remove(&dp->dp_dirty_zilogs, txg)) {
594 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
595 zil_clean(zilog, txg);
596 ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
597 dmu_buf_rele(ds->ds_dbuf, zilog);
598 }
599 ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
600 }
601
602 /*
603 * TRUE if the current thread is the tx_sync_thread or if we
604 * are being called from SPA context during pool initialization.
605 */
606 int
607 dsl_pool_sync_context(dsl_pool_t *dp)
608 {
609 return (curthread == dp->dp_tx.tx_sync_thread ||
610 spa_is_initializing(dp->dp_spa));
611 }
612
613 uint64_t
614 dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
615 {
616 uint64_t space, resv;
617
618 /*
619 * If we're trying to assess whether it's OK to do a free,
620 * cut the reservation in half to allow forward progress
621 * (e.g. make it possible to rm(1) files from a full pool).
622 */
623 space = spa_get_dspace(dp->dp_spa);
624 resv = spa_get_slop_space(dp->dp_spa);
625 if (netfree)
626 resv >>= 1;
627
628 return (space - resv);
629 }
630
631 boolean_t
632 dsl_pool_need_dirty_delay(dsl_pool_t *dp)
633 {
634 uint64_t delay_min_bytes =
635 zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
636 boolean_t rv;
637
638 mutex_enter(&dp->dp_lock);
639 if (dp->dp_dirty_total > zfs_dirty_data_sync)
640 txg_kick(dp);
641 rv = (dp->dp_dirty_total > delay_min_bytes);
642 mutex_exit(&dp->dp_lock);
643 return (rv);
644 }
645
646 void
647 dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
648 {
649 if (space > 0) {
650 mutex_enter(&dp->dp_lock);
651 dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
652 dsl_pool_dirty_delta(dp, space);
653 mutex_exit(&dp->dp_lock);
654 }
655 }
656
657 void
658 dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
659 {
660 ASSERT3S(space, >=, 0);
661 if (space == 0)
662 return;
663 mutex_enter(&dp->dp_lock);
664 if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
665 /* XXX writing something we didn't dirty? */
666 space = dp->dp_dirty_pertxg[txg & TXG_MASK];
667 }
668 ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
669 dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
670 ASSERT3U(dp->dp_dirty_total, >=, space);
671 dsl_pool_dirty_delta(dp, -space);
672 mutex_exit(&dp->dp_lock);
673 }
674
675 /* ARGSUSED */
676 static int
677 upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
678 {
679 dmu_tx_t *tx = arg;
680 dsl_dataset_t *ds, *prev = NULL;
681 int err;
682
683 err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
684 if (err)
685 return (err);
686
687 while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
688 err = dsl_dataset_hold_obj(dp,
689 dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
690 if (err) {
691 dsl_dataset_rele(ds, FTAG);
692 return (err);
693 }
694
695 if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object)
696 break;
697 dsl_dataset_rele(ds, FTAG);
698 ds = prev;
699 prev = NULL;
700 }
701
702 if (prev == NULL) {
703 prev = dp->dp_origin_snap;
704
705 /*
706 * The $ORIGIN can't have any data, or the accounting
707 * will be wrong.
708 */
709 ASSERT0(dsl_dataset_phys(prev)->ds_bp.blk_birth);
710
711 /* The origin doesn't get attached to itself */
712 if (ds->ds_object == prev->ds_object) {
713 dsl_dataset_rele(ds, FTAG);
714 return (0);
715 }
716
717 dmu_buf_will_dirty(ds->ds_dbuf, tx);
718 dsl_dataset_phys(ds)->ds_prev_snap_obj = prev->ds_object;
719 dsl_dataset_phys(ds)->ds_prev_snap_txg =
720 dsl_dataset_phys(prev)->ds_creation_txg;
721
722 dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
723 dsl_dir_phys(ds->ds_dir)->dd_origin_obj = prev->ds_object;
724
725 dmu_buf_will_dirty(prev->ds_dbuf, tx);
726 dsl_dataset_phys(prev)->ds_num_children++;
727
728 if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0) {
729 ASSERT(ds->ds_prev == NULL);
730 VERIFY0(dsl_dataset_hold_obj(dp,
731 dsl_dataset_phys(ds)->ds_prev_snap_obj,
732 ds, &ds->ds_prev));
733 }
734 }
735
736 ASSERT3U(dsl_dir_phys(ds->ds_dir)->dd_origin_obj, ==, prev->ds_object);
737 ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_obj, ==, prev->ds_object);
738
739 if (dsl_dataset_phys(prev)->ds_next_clones_obj == 0) {
740 dmu_buf_will_dirty(prev->ds_dbuf, tx);
741 dsl_dataset_phys(prev)->ds_next_clones_obj =
742 zap_create(dp->dp_meta_objset,
743 DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
744 }
745 VERIFY0(zap_add_int(dp->dp_meta_objset,
746 dsl_dataset_phys(prev)->ds_next_clones_obj, ds->ds_object, tx));
747
748 dsl_dataset_rele(ds, FTAG);
749 if (prev != dp->dp_origin_snap)
750 dsl_dataset_rele(prev, FTAG);
751 return (0);
752 }
753
754 void
755 dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
756 {
757 ASSERT(dmu_tx_is_syncing(tx));
758 ASSERT(dp->dp_origin_snap != NULL);
759
760 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
761 tx, DS_FIND_CHILDREN));
762 }
763
764 /* ARGSUSED */
765 static int
766 upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
767 {
768 dmu_tx_t *tx = arg;
769 objset_t *mos = dp->dp_meta_objset;
770
771 if (dsl_dir_phys(ds->ds_dir)->dd_origin_obj != 0) {
772 dsl_dataset_t *origin;
773
774 VERIFY0(dsl_dataset_hold_obj(dp,
775 dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &origin));
776
777 if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) {
778 dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
779 dsl_dir_phys(origin->ds_dir)->dd_clones =
780 zap_create(mos, DMU_OT_DSL_CLONES, DMU_OT_NONE,
781 0, tx);
782 }
783
784 VERIFY0(zap_add_int(dp->dp_meta_objset,
785 dsl_dir_phys(origin->ds_dir)->dd_clones,
786 ds->ds_object, tx));
787
788 dsl_dataset_rele(origin, FTAG);
789 }
790 return (0);
791 }
792
793 void
794 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
795 {
796 ASSERT(dmu_tx_is_syncing(tx));
797 uint64_t obj;
798
799 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
800 VERIFY0(dsl_pool_open_special_dir(dp,
801 FREE_DIR_NAME, &dp->dp_free_dir));
802
803 /*
804 * We can't use bpobj_alloc(), because spa_version() still
805 * returns the old version, and we need a new-version bpobj with
806 * subobj support. So call dmu_object_alloc() directly.
807 */
808 obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
809 SPA_OLD_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
810 VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
811 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
812 VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
813
814 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
815 upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN));
816 }
817
818 void
819 dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
820 {
821 uint64_t dsobj;
822 dsl_dataset_t *ds;
823
824 ASSERT(dmu_tx_is_syncing(tx));
825 ASSERT(dp->dp_origin_snap == NULL);
826 ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
827
828 /* create the origin dir, ds, & snap-ds */
829 dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
830 NULL, 0, kcred, tx);
831 VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
832 dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
833 VERIFY0(dsl_dataset_hold_obj(dp, dsl_dataset_phys(ds)->ds_prev_snap_obj,
834 dp, &dp->dp_origin_snap));
835 dsl_dataset_rele(ds, FTAG);
836 }
837
838 taskq_t *
839 dsl_pool_vnrele_taskq(dsl_pool_t *dp)
840 {
841 return (dp->dp_vnrele_taskq);
842 }
843
844 /*
845 * Walk through the pool-wide zap object of temporary snapshot user holds
846 * and release them.
847 */
848 void
849 dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
850 {
851 zap_attribute_t za;
852 zap_cursor_t zc;
853 objset_t *mos = dp->dp_meta_objset;
854 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
855 nvlist_t *holds;
856
857 if (zapobj == 0)
858 return;
859 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
860
861 holds = fnvlist_alloc();
862
863 for (zap_cursor_init(&zc, mos, zapobj);
864 zap_cursor_retrieve(&zc, &za) == 0;
865 zap_cursor_advance(&zc)) {
866 char *htag;
867 nvlist_t *tags;
868
869 htag = strchr(za.za_name, '-');
870 *htag = '\0';
871 ++htag;
872 if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
873 tags = fnvlist_alloc();
874 fnvlist_add_boolean(tags, htag);
875 fnvlist_add_nvlist(holds, za.za_name, tags);
876 fnvlist_free(tags);
877 } else {
878 fnvlist_add_boolean(tags, htag);
879 }
880 }
881 dsl_dataset_user_release_tmp(dp, holds);
882 fnvlist_free(holds);
883 zap_cursor_fini(&zc);
884 }
885
886 /*
887 * Create the pool-wide zap object for storing temporary snapshot holds.
888 */
889 void
890 dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
891 {
892 objset_t *mos = dp->dp_meta_objset;
893
894 ASSERT(dp->dp_tmp_userrefs_obj == 0);
895 ASSERT(dmu_tx_is_syncing(tx));
896
897 dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
898 DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
899 }
900
901 static int
902 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
903 const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
904 {
905 objset_t *mos = dp->dp_meta_objset;
906 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
907 char *name;
908 int error;
909
910 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
911 ASSERT(dmu_tx_is_syncing(tx));
912
913 /*
914 * If the pool was created prior to SPA_VERSION_USERREFS, the
915 * zap object for temporary holds might not exist yet.
916 */
917 if (zapobj == 0) {
918 if (holding) {
919 dsl_pool_user_hold_create_obj(dp, tx);
920 zapobj = dp->dp_tmp_userrefs_obj;
921 } else {
922 return (SET_ERROR(ENOENT));
923 }
924 }
925
926 name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
927 if (holding)
928 error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
929 else
930 error = zap_remove(mos, zapobj, name, tx);
931 strfree(name);
932
933 return (error);
934 }
935
936 /*
937 * Add a temporary hold for the given dataset object and tag.
938 */
939 int
940 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
941 uint64_t now, dmu_tx_t *tx)
942 {
943 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
944 }
945
946 /*
947 * Release a temporary hold for the given dataset object and tag.
948 */
949 int
950 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
951 dmu_tx_t *tx)
952 {
953 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, NULL,
954 tx, B_FALSE));
955 }
956
957 /*
958 * DSL Pool Configuration Lock
959 *
960 * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
961 * creation / destruction / rename / property setting). It must be held for
962 * read to hold a dataset or dsl_dir. I.e. you must call
963 * dsl_pool_config_enter() or dsl_pool_hold() before calling
964 * dsl_{dataset,dir}_hold{_obj}. In most circumstances, the dp_config_rwlock
965 * must be held continuously until all datasets and dsl_dirs are released.
966 *
967 * The only exception to this rule is that if a "long hold" is placed on
968 * a dataset, then the dp_config_rwlock may be dropped while the dataset
969 * is still held. The long hold will prevent the dataset from being
970 * destroyed -- the destroy will fail with EBUSY. A long hold can be
971 * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
972 * (by calling dsl_{dataset,objset}_{try}own{_obj}).
973 *
974 * Legitimate long-holders (including owners) should be long-running, cancelable
975 * tasks that should cause "zfs destroy" to fail. This includes DMU
976 * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
977 * "zfs send", and "zfs diff". There are several other long-holders whose
978 * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
979 *
980 * The usual formula for long-holding would be:
981 * dsl_pool_hold()
982 * dsl_dataset_hold()
983 * ... perform checks ...
984 * dsl_dataset_long_hold()
985 * dsl_pool_rele()
986 * ... perform long-running task ...
987 * dsl_dataset_long_rele()
988 * dsl_dataset_rele()
989 *
990 * Note that when the long hold is released, the dataset is still held but
991 * the pool is not held. The dataset may change arbitrarily during this time
992 * (e.g. it could be destroyed). Therefore you shouldn't do anything to the
993 * dataset except release it.
994 *
995 * User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
996 * or modifying operations.
997 *
998 * Modifying operations should generally use dsl_sync_task(). The synctask
999 * infrastructure enforces proper locking strategy with respect to the
1000 * dp_config_rwlock. See the comment above dsl_sync_task() for details.
1001 *
1002 * Read-only operations will manually hold the pool, then the dataset, obtain
1003 * information from the dataset, then release the pool and dataset.
1004 * dmu_objset_{hold,rele}() are convenience routines that also do the pool
1005 * hold/rele.
1006 */
1007
1008 int
1009 dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
1010 {
1011 spa_t *spa;
1012 int error;
1013
1014 error = spa_open(name, &spa, tag);
1015 if (error == 0) {
1016 *dp = spa_get_dsl(spa);
1017 dsl_pool_config_enter(*dp, tag);
1018 }
1019 return (error);
1020 }
1021
1022 void
1023 dsl_pool_rele(dsl_pool_t *dp, void *tag)
1024 {
1025 dsl_pool_config_exit(dp, tag);
1026 spa_close(dp->dp_spa, tag);
1027 }
1028
1029 void
1030 dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
1031 {
1032 /*
1033 * We use a "reentrant" reader-writer lock, but not reentrantly.
1034 *
1035 * The rrwlock can (with the track_all flag) track all reading threads,
1036 * which is very useful for debugging which code path failed to release
1037 * the lock, and for verifying that the *current* thread does hold
1038 * the lock.
1039 *
1040 * (Unlike a rwlock, which knows that N threads hold it for
1041 * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
1042 * if any thread holds it for read, even if this thread doesn't).
1043 */
1044 ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1045 rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
1046 }
1047
1048 void
1049 dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
1050 {
1051 rrw_exit(&dp->dp_config_rwlock, tag);
1052 }
1053
1054 boolean_t
1055 dsl_pool_config_held(dsl_pool_t *dp)
1056 {
1057 return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
1058 }