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