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 ASSERT3S(space, >=, 0);
654 if (space == 0)
655 return;
656 mutex_enter(&dp->dp_lock);
657 if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
658 /* XXX writing something we didn't dirty? */
659 space = dp->dp_dirty_pertxg[txg & TXG_MASK];
660 }
661 ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
662 dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
663 ASSERT3U(dp->dp_dirty_total, >=, space);
664 dsl_pool_dirty_delta(dp, -space);
665 mutex_exit(&dp->dp_lock);
666 }
667
668 /* ARGSUSED */
669 static int
670 upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
671 {
672 dmu_tx_t *tx = arg;
673 dsl_dataset_t *ds, *prev = NULL;
674 int err;
675
676 err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
677 if (err)
678 return (err);
679
680 while (ds->ds_phys->ds_prev_snap_obj != 0) {
681 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
682 FTAG, &prev);
683 if (err) {
684 dsl_dataset_rele(ds, FTAG);
685 return (err);
686 }
687
688 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object)
689 break;
690 dsl_dataset_rele(ds, FTAG);
691 ds = prev;
692 prev = NULL;
693 }
694
695 if (prev == NULL) {
696 prev = dp->dp_origin_snap;
697
698 /*
699 * The $ORIGIN can't have any data, or the accounting
700 * will be wrong.
701 */
702 ASSERT0(prev->ds_phys->ds_bp.blk_birth);
703
704 /* The origin doesn't get attached to itself */
705 if (ds->ds_object == prev->ds_object) {
706 dsl_dataset_rele(ds, FTAG);
707 return (0);
708 }
709
710 dmu_buf_will_dirty(ds->ds_dbuf, tx);
711 ds->ds_phys->ds_prev_snap_obj = prev->ds_object;
712 ds->ds_phys->ds_prev_snap_txg = prev->ds_phys->ds_creation_txg;
713
714 dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
715 ds->ds_dir->dd_phys->dd_origin_obj = prev->ds_object;
716
717 dmu_buf_will_dirty(prev->ds_dbuf, tx);
718 prev->ds_phys->ds_num_children++;
719
720 if (ds->ds_phys->ds_next_snap_obj == 0) {
721 ASSERT(ds->ds_prev == NULL);
722 VERIFY0(dsl_dataset_hold_obj(dp,
723 ds->ds_phys->ds_prev_snap_obj, ds, &ds->ds_prev));
724 }
725 }
726
727 ASSERT3U(ds->ds_dir->dd_phys->dd_origin_obj, ==, prev->ds_object);
728 ASSERT3U(ds->ds_phys->ds_prev_snap_obj, ==, prev->ds_object);
729
730 if (prev->ds_phys->ds_next_clones_obj == 0) {
731 dmu_buf_will_dirty(prev->ds_dbuf, tx);
732 prev->ds_phys->ds_next_clones_obj =
733 zap_create(dp->dp_meta_objset,
734 DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
735 }
736 VERIFY0(zap_add_int(dp->dp_meta_objset,
737 prev->ds_phys->ds_next_clones_obj, ds->ds_object, tx));
738
739 dsl_dataset_rele(ds, FTAG);
740 if (prev != dp->dp_origin_snap)
741 dsl_dataset_rele(prev, FTAG);
742 return (0);
743 }
744
745 void
746 dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
747 {
748 ASSERT(dmu_tx_is_syncing(tx));
749 ASSERT(dp->dp_origin_snap != NULL);
750
751 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
752 tx, DS_FIND_CHILDREN));
753 }
754
755 /* ARGSUSED */
756 static int
757 upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
758 {
759 dmu_tx_t *tx = arg;
760 objset_t *mos = dp->dp_meta_objset;
761
762 if (ds->ds_dir->dd_phys->dd_origin_obj != 0) {
763 dsl_dataset_t *origin;
764
765 VERIFY0(dsl_dataset_hold_obj(dp,
766 ds->ds_dir->dd_phys->dd_origin_obj, FTAG, &origin));
767
768 if (origin->ds_dir->dd_phys->dd_clones == 0) {
769 dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
770 origin->ds_dir->dd_phys->dd_clones = zap_create(mos,
771 DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
772 }
773
774 VERIFY0(zap_add_int(dp->dp_meta_objset,
775 origin->ds_dir->dd_phys->dd_clones, ds->ds_object, tx));
776
777 dsl_dataset_rele(origin, FTAG);
778 }
779 return (0);
780 }
781
782 void
783 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
784 {
785 ASSERT(dmu_tx_is_syncing(tx));
786 uint64_t obj;
787
788 (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
789 VERIFY0(dsl_pool_open_special_dir(dp,
790 FREE_DIR_NAME, &dp->dp_free_dir));
791
792 /*
793 * We can't use bpobj_alloc(), because spa_version() still
794 * returns the old version, and we need a new-version bpobj with
795 * subobj support. So call dmu_object_alloc() directly.
796 */
797 obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
798 SPA_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
799 VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
800 DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
801 VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
802
803 VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
804 upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN));
805 }
806
807 void
808 dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
809 {
810 uint64_t dsobj;
811 dsl_dataset_t *ds;
812
813 ASSERT(dmu_tx_is_syncing(tx));
814 ASSERT(dp->dp_origin_snap == NULL);
815 ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
816
817 /* create the origin dir, ds, & snap-ds */
818 dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
819 NULL, 0, kcred, tx);
820 VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
821 dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
822 VERIFY0(dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
823 dp, &dp->dp_origin_snap));
824 dsl_dataset_rele(ds, FTAG);
825 }
826
827 taskq_t *
828 dsl_pool_vnrele_taskq(dsl_pool_t *dp)
829 {
830 return (dp->dp_vnrele_taskq);
831 }
832
833 /*
834 * Walk through the pool-wide zap object of temporary snapshot user holds
835 * and release them.
836 */
837 void
838 dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
839 {
840 zap_attribute_t za;
841 zap_cursor_t zc;
842 objset_t *mos = dp->dp_meta_objset;
843 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
844 nvlist_t *holds;
845
846 if (zapobj == 0)
847 return;
848 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
849
850 holds = fnvlist_alloc();
851
852 for (zap_cursor_init(&zc, mos, zapobj);
853 zap_cursor_retrieve(&zc, &za) == 0;
854 zap_cursor_advance(&zc)) {
855 char *htag;
856 nvlist_t *tags;
857
858 htag = strchr(za.za_name, '-');
859 *htag = '\0';
860 ++htag;
861 if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
862 tags = fnvlist_alloc();
863 fnvlist_add_boolean(tags, htag);
864 fnvlist_add_nvlist(holds, za.za_name, tags);
865 fnvlist_free(tags);
866 } else {
867 fnvlist_add_boolean(tags, htag);
868 }
869 }
870 dsl_dataset_user_release_tmp(dp, holds);
871 fnvlist_free(holds);
872 zap_cursor_fini(&zc);
873 }
874
875 /*
876 * Create the pool-wide zap object for storing temporary snapshot holds.
877 */
878 void
879 dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
880 {
881 objset_t *mos = dp->dp_meta_objset;
882
883 ASSERT(dp->dp_tmp_userrefs_obj == 0);
884 ASSERT(dmu_tx_is_syncing(tx));
885
886 dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
887 DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
888 }
889
890 static int
891 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
892 const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
893 {
894 objset_t *mos = dp->dp_meta_objset;
895 uint64_t zapobj = dp->dp_tmp_userrefs_obj;
896 char *name;
897 int error;
898
899 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
900 ASSERT(dmu_tx_is_syncing(tx));
901
902 /*
903 * If the pool was created prior to SPA_VERSION_USERREFS, the
904 * zap object for temporary holds might not exist yet.
905 */
906 if (zapobj == 0) {
907 if (holding) {
908 dsl_pool_user_hold_create_obj(dp, tx);
909 zapobj = dp->dp_tmp_userrefs_obj;
910 } else {
911 return (SET_ERROR(ENOENT));
912 }
913 }
914
915 name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
916 if (holding)
917 error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
918 else
919 error = zap_remove(mos, zapobj, name, tx);
920 strfree(name);
921
922 return (error);
923 }
924
925 /*
926 * Add a temporary hold for the given dataset object and tag.
927 */
928 int
929 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
930 uint64_t now, dmu_tx_t *tx)
931 {
932 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
933 }
934
935 /*
936 * Release a temporary hold for the given dataset object and tag.
937 */
938 int
939 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
940 dmu_tx_t *tx)
941 {
942 return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, NULL,
943 tx, B_FALSE));
944 }
945
946 /*
947 * DSL Pool Configuration Lock
948 *
949 * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
950 * creation / destruction / rename / property setting). It must be held for
951 * read to hold a dataset or dsl_dir. I.e. you must call
952 * dsl_pool_config_enter() or dsl_pool_hold() before calling
953 * dsl_{dataset,dir}_hold{_obj}. In most circumstances, the dp_config_rwlock
954 * must be held continuously until all datasets and dsl_dirs are released.
955 *
956 * The only exception to this rule is that if a "long hold" is placed on
957 * a dataset, then the dp_config_rwlock may be dropped while the dataset
958 * is still held. The long hold will prevent the dataset from being
959 * destroyed -- the destroy will fail with EBUSY. A long hold can be
960 * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
961 * (by calling dsl_{dataset,objset}_{try}own{_obj}).
962 *
963 * Legitimate long-holders (including owners) should be long-running, cancelable
964 * tasks that should cause "zfs destroy" to fail. This includes DMU
965 * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
966 * "zfs send", and "zfs diff". There are several other long-holders whose
967 * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
968 *
969 * The usual formula for long-holding would be:
970 * dsl_pool_hold()
971 * dsl_dataset_hold()
972 * ... perform checks ...
973 * dsl_dataset_long_hold()
974 * dsl_pool_rele()
975 * ... perform long-running task ...
976 * dsl_dataset_long_rele()
977 * dsl_dataset_rele()
978 *
979 * Note that when the long hold is released, the dataset is still held but
980 * the pool is not held. The dataset may change arbitrarily during this time
981 * (e.g. it could be destroyed). Therefore you shouldn't do anything to the
982 * dataset except release it.
983 *
984 * User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
985 * or modifying operations.
986 *
987 * Modifying operations should generally use dsl_sync_task(). The synctask
988 * infrastructure enforces proper locking strategy with respect to the
989 * dp_config_rwlock. See the comment above dsl_sync_task() for details.
990 *
991 * Read-only operations will manually hold the pool, then the dataset, obtain
992 * information from the dataset, then release the pool and dataset.
993 * dmu_objset_{hold,rele}() are convenience routines that also do the pool
994 * hold/rele.
995 */
996
997 int
998 dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
999 {
1000 spa_t *spa;
1001 int error;
1002
1003 error = spa_open(name, &spa, tag);
1004 if (error == 0) {
1005 *dp = spa_get_dsl(spa);
1006 dsl_pool_config_enter(*dp, tag);
1007 }
1008 return (error);
1009 }
1010
1011 void
1012 dsl_pool_rele(dsl_pool_t *dp, void *tag)
1013 {
1014 dsl_pool_config_exit(dp, tag);
1015 spa_close(dp->dp_spa, tag);
1016 }
1017
1018 void
1019 dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
1020 {
1021 /*
1022 * We use a "reentrant" reader-writer lock, but not reentrantly.
1023 *
1024 * The rrwlock can (with the track_all flag) track all reading threads,
1025 * which is very useful for debugging which code path failed to release
1026 * the lock, and for verifying that the *current* thread does hold
1027 * the lock.
1028 *
1029 * (Unlike a rwlock, which knows that N threads hold it for
1030 * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
1031 * if any thread holds it for read, even if this thread doesn't).
1032 */
1033 ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
1034 rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
1035 }
1036
1037 void
1038 dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
1039 {
1040 rrw_exit(&dp->dp_config_rwlock, tag);
1041 }
1042
1043 boolean_t
1044 dsl_pool_config_held(dsl_pool_t *dp)
1045 {
1046 return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
1047 }