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 * Portions Copyright 2011 Martin Matuska
24 * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
25 */
26
27 #include <sys/zfs_context.h>
28 #include <sys/txg_impl.h>
29 #include <sys/dmu_impl.h>
30 #include <sys/dmu_tx.h>
31 #include <sys/dsl_pool.h>
32 #include <sys/dsl_scan.h>
33 #include <sys/zil.h>
34 #include <sys/callb.h>
35
36 /*
37 * ZFS Transaction Groups
38 * ----------------------
39 *
40 * ZFS transaction groups are, as the name implies, groups of transactions
41 * that act on persistent state. ZFS asserts consistency at the granularity of
42 * these transaction groups. Each successive transaction group (txg) is
43 * assigned a 64-bit consecutive identifier. There are three active
44 * transaction group states: open, quiescing, or syncing. At any given time,
45 * there may be an active txg associated with each state; each active txg may
46 * either be processing, or blocked waiting to enter the next state. There may
47 * be up to three active txgs, and there is always a txg in the open state
48 * (though it may be blocked waiting to enter the quiescing state). In broad
49 * strokes, transactions -- operations that change in-memory structures -- are
50 * accepted into the txg in the open state, and are completed while the txg is
51 * in the open or quiescing states. The accumulated changes are written to
52 * disk in the syncing state.
53 *
54 * Open
55 *
56 * When a new txg becomes active, it first enters the open state. New
57 * transactions -- updates to in-memory structures -- are assigned to the
58 * currently open txg. There is always a txg in the open state so that ZFS can
59 * accept new changes (though the txg may refuse new changes if it has hit
60 * some limit). ZFS advances the open txg to the next state for a variety of
61 * reasons such as it hitting a time or size threshold, or the execution of an
62 * administrative action that must be completed in the syncing state.
63 *
64 * Quiescing
65 *
66 * After a txg exits the open state, it enters the quiescing state. The
67 * quiescing state is intended to provide a buffer between accepting new
68 * transactions in the open state and writing them out to stable storage in
69 * the syncing state. While quiescing, transactions can continue their
70 * operation without delaying either of the other states. Typically, a txg is
71 * in the quiescing state very briefly since the operations are bounded by
72 * software latencies rather than, say, slower I/O latencies. After all
73 * transactions complete, the txg is ready to enter the next state.
74 *
75 * Syncing
76 *
77 * In the syncing state, the in-memory state built up during the open and (to
78 * a lesser degree) the quiescing states is written to stable storage. The
79 * process of writing out modified data can, in turn modify more data. For
80 * example when we write new blocks, we need to allocate space for them; those
81 * allocations modify metadata (space maps)... which themselves must be
82 * written to stable storage. During the sync state, ZFS iterates, writing out
83 * data until it converges and all in-memory changes have been written out.
84 * The first such pass is the largest as it encompasses all the modified user
85 * data (as opposed to filesystem metadata). Subsequent passes typically have
86 * far less data to write as they consist exclusively of filesystem metadata.
87 *
88 * To ensure convergence, after a certain number of passes ZFS begins
89 * overwriting locations on stable storage that had been allocated earlier in
90 * the syncing state (and subsequently freed). ZFS usually allocates new
91 * blocks to optimize for large, continuous, writes. For the syncing state to
92 * converge however it must complete a pass where no new blocks are allocated
93 * since each allocation requires a modification of persistent metadata.
94 * Further, to hasten convergence, after a prescribed number of passes, ZFS
95 * also defers frees, and stops compressing.
96 *
97 * In addition to writing out user data, we must also execute synctasks during
98 * the syncing context. A synctask is the mechanism by which some
99 * administrative activities work such as creating and destroying snapshots or
100 * datasets. Note that when a synctask is initiated it enters the open txg,
101 * and ZFS then pushes that txg as quickly as possible to completion of the
102 * syncing state in order to reduce the latency of the administrative
103 * activity. To complete the syncing state, ZFS writes out a new uberblock,
104 * the root of the tree of blocks that comprise all state stored on the ZFS
105 * pool. Finally, if there is a quiesced txg waiting, we signal that it can
106 * now transition to the syncing state.
107 */
108
109 static void txg_sync_thread(void *arg);
110 static void txg_quiesce_thread(void *arg);
111
112 int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */
113
114 /*
115 * Prepare the txg subsystem.
116 */
117 void
118 txg_init(dsl_pool_t *dp, uint64_t txg)
119 {
120 tx_state_t *tx = &dp->dp_tx;
121 int c;
122 bzero(tx, sizeof (tx_state_t));
123
124 tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
125
126 for (c = 0; c < max_ncpus; c++) {
127 int i;
128
129 mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
130 mutex_init(&tx->tx_cpu[c].tc_open_lock, NULL, MUTEX_DEFAULT,
131 NULL);
132 for (i = 0; i < TXG_SIZE; i++) {
133 cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
134 NULL);
135 list_create(&tx->tx_cpu[c].tc_callbacks[i],
136 sizeof (dmu_tx_callback_t),
137 offsetof(dmu_tx_callback_t, dcb_node));
138 }
139 }
140
141 mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);
142
143 cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
144 cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
145 cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
146 cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
147 cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);
148
149 tx->tx_open_txg = txg;
150 }
151
152 /*
153 * Close down the txg subsystem.
154 */
155 void
156 txg_fini(dsl_pool_t *dp)
157 {
158 tx_state_t *tx = &dp->dp_tx;
159 int c;
160
161 ASSERT0(tx->tx_threads);
162
163 mutex_destroy(&tx->tx_sync_lock);
164
165 cv_destroy(&tx->tx_sync_more_cv);
166 cv_destroy(&tx->tx_sync_done_cv);
167 cv_destroy(&tx->tx_quiesce_more_cv);
168 cv_destroy(&tx->tx_quiesce_done_cv);
169 cv_destroy(&tx->tx_exit_cv);
170
171 for (c = 0; c < max_ncpus; c++) {
172 int i;
173
174 mutex_destroy(&tx->tx_cpu[c].tc_open_lock);
175 mutex_destroy(&tx->tx_cpu[c].tc_lock);
176 for (i = 0; i < TXG_SIZE; i++) {
177 cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
178 list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
179 }
180 }
181
182 if (tx->tx_commit_cb_taskq != NULL)
183 taskq_destroy(tx->tx_commit_cb_taskq);
184
185 kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
186
187 bzero(tx, sizeof (tx_state_t));
188 }
189
190 /*
191 * Start syncing transaction groups.
192 */
193 void
194 txg_sync_start(dsl_pool_t *dp)
195 {
196 tx_state_t *tx = &dp->dp_tx;
197
198 mutex_enter(&tx->tx_sync_lock);
199
200 dprintf("pool %p\n", dp);
201
202 ASSERT0(tx->tx_threads);
203
204 tx->tx_threads = 2;
205
206 tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
207 dp, 0, &p0, TS_RUN, minclsyspri);
208
209 /*
210 * The sync thread can need a larger-than-default stack size on
211 * 32-bit x86. This is due in part to nested pools and
212 * scrub_visitbp() recursion.
213 */
214 tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread,
215 dp, 0, &p0, TS_RUN, minclsyspri);
216
217 mutex_exit(&tx->tx_sync_lock);
218 }
219
220 static void
221 txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr)
222 {
223 CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
224 mutex_enter(&tx->tx_sync_lock);
225 }
226
227 static void
228 txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp)
229 {
230 ASSERT(*tpp != NULL);
231 *tpp = NULL;
232 tx->tx_threads--;
233 cv_broadcast(&tx->tx_exit_cv);
234 CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */
235 thread_exit();
236 }
237
238 static void
239 txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time)
240 {
241 CALLB_CPR_SAFE_BEGIN(cpr);
242
243 if (time)
244 (void) cv_timedwait(cv, &tx->tx_sync_lock,
245 ddi_get_lbolt() + time);
246 else
247 cv_wait(cv, &tx->tx_sync_lock);
248
249 CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
250 }
251
252 /*
253 * Stop syncing transaction groups.
254 */
255 void
256 txg_sync_stop(dsl_pool_t *dp)
257 {
258 tx_state_t *tx = &dp->dp_tx;
259
260 dprintf("pool %p\n", dp);
261 /*
262 * Finish off any work in progress.
263 */
264 ASSERT3U(tx->tx_threads, ==, 2);
265
266 /*
267 * We need to ensure that we've vacated the deferred space_maps.
268 */
269 txg_wait_synced(dp, tx->tx_open_txg + TXG_DEFER_SIZE);
270
271 /*
272 * Wake all sync threads and wait for them to die.
273 */
274 mutex_enter(&tx->tx_sync_lock);
275
276 ASSERT3U(tx->tx_threads, ==, 2);
277
278 tx->tx_exiting = 1;
279
280 cv_broadcast(&tx->tx_quiesce_more_cv);
281 cv_broadcast(&tx->tx_quiesce_done_cv);
282 cv_broadcast(&tx->tx_sync_more_cv);
283
284 while (tx->tx_threads != 0)
285 cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);
286
287 tx->tx_exiting = 0;
288
289 mutex_exit(&tx->tx_sync_lock);
290 }
291
292 uint64_t
293 txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
294 {
295 tx_state_t *tx = &dp->dp_tx;
296 tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
297 uint64_t txg;
298
299 mutex_enter(&tc->tc_open_lock);
300 txg = tx->tx_open_txg;
301
302 mutex_enter(&tc->tc_lock);
303 tc->tc_count[txg & TXG_MASK]++;
304 mutex_exit(&tc->tc_lock);
305
306 th->th_cpu = tc;
307 th->th_txg = txg;
308
309 return (txg);
310 }
311
312 void
313 txg_rele_to_quiesce(txg_handle_t *th)
314 {
315 tx_cpu_t *tc = th->th_cpu;
316
317 ASSERT(!MUTEX_HELD(&tc->tc_lock));
318 mutex_exit(&tc->tc_open_lock);
319 }
320
321 void
322 txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
323 {
324 tx_cpu_t *tc = th->th_cpu;
325 int g = th->th_txg & TXG_MASK;
326
327 mutex_enter(&tc->tc_lock);
328 list_move_tail(&tc->tc_callbacks[g], tx_callbacks);
329 mutex_exit(&tc->tc_lock);
330 }
331
332 void
333 txg_rele_to_sync(txg_handle_t *th)
334 {
335 tx_cpu_t *tc = th->th_cpu;
336 int g = th->th_txg & TXG_MASK;
337
338 mutex_enter(&tc->tc_lock);
339 ASSERT(tc->tc_count[g] != 0);
340 if (--tc->tc_count[g] == 0)
341 cv_broadcast(&tc->tc_cv[g]);
342 mutex_exit(&tc->tc_lock);
343
344 th->th_cpu = NULL; /* defensive */
345 }
346
347 /*
348 * Blocks until all transactions in the group are committed.
349 *
350 * On return, the transaction group has reached a stable state in which it can
351 * then be passed off to the syncing context.
352 */
353 static void
354 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
355 {
356 tx_state_t *tx = &dp->dp_tx;
357 int g = txg & TXG_MASK;
358 int c;
359
360 /*
361 * Grab all tc_open_locks so nobody else can get into this txg.
362 */
363 for (c = 0; c < max_ncpus; c++)
364 mutex_enter(&tx->tx_cpu[c].tc_open_lock);
365
366 ASSERT(txg == tx->tx_open_txg);
367 tx->tx_open_txg++;
368 tx->tx_open_time = gethrtime();
369
370 DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg);
371 DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg);
372
373 /*
374 * Now that we've incremented tx_open_txg, we can let threads
375 * enter the next transaction group.
376 */
377 for (c = 0; c < max_ncpus; c++)
378 mutex_exit(&tx->tx_cpu[c].tc_open_lock);
379
380 /*
381 * Quiesce the transaction group by waiting for everyone to txg_exit().
382 */
383 for (c = 0; c < max_ncpus; c++) {
384 tx_cpu_t *tc = &tx->tx_cpu[c];
385 mutex_enter(&tc->tc_lock);
386 while (tc->tc_count[g] != 0)
387 cv_wait(&tc->tc_cv[g], &tc->tc_lock);
388 mutex_exit(&tc->tc_lock);
389 }
390 }
391
392 static void
393 txg_do_callbacks(list_t *cb_list)
394 {
395 dmu_tx_do_callbacks(cb_list, 0);
396
397 list_destroy(cb_list);
398
399 kmem_free(cb_list, sizeof (list_t));
400 }
401
402 /*
403 * Dispatch the commit callbacks registered on this txg to worker threads.
404 *
405 * If no callbacks are registered for a given TXG, nothing happens.
406 * This function creates a taskq for the associated pool, if needed.
407 */
408 static void
409 txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
410 {
411 int c;
412 tx_state_t *tx = &dp->dp_tx;
413 list_t *cb_list;
414
415 for (c = 0; c < max_ncpus; c++) {
416 tx_cpu_t *tc = &tx->tx_cpu[c];
417 /*
418 * No need to lock tx_cpu_t at this point, since this can
419 * only be called once a txg has been synced.
420 */
421
422 int g = txg & TXG_MASK;
423
424 if (list_is_empty(&tc->tc_callbacks[g]))
425 continue;
426
427 if (tx->tx_commit_cb_taskq == NULL) {
428 /*
429 * Commit callback taskq hasn't been created yet.
430 */
431 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
432 max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
433 TASKQ_PREPOPULATE);
434 }
435
436 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
437 list_create(cb_list, sizeof (dmu_tx_callback_t),
438 offsetof(dmu_tx_callback_t, dcb_node));
439
440 list_move_tail(cb_list, &tc->tc_callbacks[g]);
441
442 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
443 txg_do_callbacks, cb_list, TQ_SLEEP);
444 }
445 }
446
447 static void
448 txg_sync_thread(void *arg)
449 {
450 dsl_pool_t *dp = arg;
451 spa_t *spa = dp->dp_spa;
452 tx_state_t *tx = &dp->dp_tx;
453 callb_cpr_t cpr;
454 uint64_t start, delta;
455
456 txg_thread_enter(tx, &cpr);
457
458 start = delta = 0;
459 for (;;) {
460 uint64_t timeout = zfs_txg_timeout * hz;
461 uint64_t timer;
462 uint64_t txg;
463
464 /*
465 * We sync when we're scanning, there's someone waiting
466 * on us, or the quiesce thread has handed off a txg to
467 * us, or we have reached our timeout.
468 */
469 timer = (delta >= timeout ? 0 : timeout - delta);
470 while (!dsl_scan_active(dp->dp_scan) &&
471 !tx->tx_exiting && timer > 0 &&
472 tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
473 tx->tx_quiesced_txg == 0 &&
474 dp->dp_dirty_total < zfs_dirty_data_sync) {
475 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
476 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
477 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
478 delta = ddi_get_lbolt() - start;
479 timer = (delta > timeout ? 0 : timeout - delta);
480 }
481
482 /*
483 * Wait until the quiesce thread hands off a txg to us,
484 * prompting it to do so if necessary.
485 */
486 while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) {
487 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
488 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
489 cv_broadcast(&tx->tx_quiesce_more_cv);
490 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
491 }
492
493 if (tx->tx_exiting)
494 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
495
496 /*
497 * Consume the quiesced txg which has been handed off to
498 * us. This may cause the quiescing thread to now be
499 * able to quiesce another txg, so we must signal it.
500 */
501 txg = tx->tx_quiesced_txg;
502 tx->tx_quiesced_txg = 0;
503 tx->tx_syncing_txg = txg;
504 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
505 cv_broadcast(&tx->tx_quiesce_more_cv);
506
507 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
508 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
509 mutex_exit(&tx->tx_sync_lock);
510
511 start = ddi_get_lbolt();
512 spa_sync(spa, txg);
513 delta = ddi_get_lbolt() - start;
514
515 mutex_enter(&tx->tx_sync_lock);
516 tx->tx_synced_txg = txg;
517 tx->tx_syncing_txg = 0;
518 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
519 cv_broadcast(&tx->tx_sync_done_cv);
520
521 /*
522 * Dispatch commit callbacks to worker threads.
523 */
524 txg_dispatch_callbacks(dp, txg);
525 }
526 }
527
528 static void
529 txg_quiesce_thread(void *arg)
530 {
531 dsl_pool_t *dp = arg;
532 tx_state_t *tx = &dp->dp_tx;
533 callb_cpr_t cpr;
534
535 txg_thread_enter(tx, &cpr);
536
537 for (;;) {
538 uint64_t txg;
539
540 /*
541 * We quiesce when there's someone waiting on us.
542 * However, we can only have one txg in "quiescing" or
543 * "quiesced, waiting to sync" state. So we wait until
544 * the "quiesced, waiting to sync" txg has been consumed
545 * by the sync thread.
546 */
547 while (!tx->tx_exiting &&
548 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
549 tx->tx_quiesced_txg != 0))
550 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
551
552 if (tx->tx_exiting)
553 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
554
555 txg = tx->tx_open_txg;
556 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
557 txg, tx->tx_quiesce_txg_waiting,
558 tx->tx_sync_txg_waiting);
559 mutex_exit(&tx->tx_sync_lock);
560 txg_quiesce(dp, txg);
561 mutex_enter(&tx->tx_sync_lock);
562
563 /*
564 * Hand this txg off to the sync thread.
565 */
566 dprintf("quiesce done, handing off txg %llu\n", txg);
567 tx->tx_quiesced_txg = txg;
568 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
569 cv_broadcast(&tx->tx_sync_more_cv);
570 cv_broadcast(&tx->tx_quiesce_done_cv);
571 }
572 }
573
574 /*
575 * Delay this thread by delay nanoseconds if we are still in the open
576 * transaction group and there is already a waiting txg quiescing or quiesced.
577 * Abort the delay if this txg stalls or enters the quiescing state.
578 */
579 void
580 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
581 {
582 tx_state_t *tx = &dp->dp_tx;
583 hrtime_t start = gethrtime();
584
585 /* don't delay if this txg could transition to quiescing immediately */
586 if (tx->tx_open_txg > txg ||
587 tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
588 return;
589
590 mutex_enter(&tx->tx_sync_lock);
591 if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
592 mutex_exit(&tx->tx_sync_lock);
593 return;
594 }
595
596 while (gethrtime() - start < delay &&
597 tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) {
598 (void) cv_timedwait_hires(&tx->tx_quiesce_more_cv,
599 &tx->tx_sync_lock, delay, resolution, 0);
600 }
601
602 mutex_exit(&tx->tx_sync_lock);
603 }
604
605 void
606 txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
607 {
608 tx_state_t *tx = &dp->dp_tx;
609
610 ASSERT(!dsl_pool_config_held(dp));
611
612 mutex_enter(&tx->tx_sync_lock);
613 ASSERT3U(tx->tx_threads, ==, 2);
614 if (txg == 0)
615 txg = tx->tx_open_txg + TXG_DEFER_SIZE;
616 if (tx->tx_sync_txg_waiting < txg)
617 tx->tx_sync_txg_waiting = txg;
618 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
619 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
620 while (tx->tx_synced_txg < txg) {
621 dprintf("broadcasting sync more "
622 "tx_synced=%llu waiting=%llu dp=%p\n",
623 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
624 cv_broadcast(&tx->tx_sync_more_cv);
625 cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
626 }
627 mutex_exit(&tx->tx_sync_lock);
628 }
629
630 void
631 txg_wait_open(dsl_pool_t *dp, uint64_t txg)
632 {
633 tx_state_t *tx = &dp->dp_tx;
634
635 ASSERT(!dsl_pool_config_held(dp));
636
637 mutex_enter(&tx->tx_sync_lock);
638 ASSERT3U(tx->tx_threads, ==, 2);
639 if (txg == 0)
640 txg = tx->tx_open_txg + 1;
641 if (tx->tx_quiesce_txg_waiting < txg)
642 tx->tx_quiesce_txg_waiting = txg;
643 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
644 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
645 while (tx->tx_open_txg < txg) {
646 cv_broadcast(&tx->tx_quiesce_more_cv);
647 cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
648 }
649 mutex_exit(&tx->tx_sync_lock);
650 }
651
652 /*
653 * If there isn't a txg syncing or in the pipeline, push another txg through
654 * the pipeline by queiscing the open txg.
655 */
656 void
657 txg_kick(dsl_pool_t *dp)
658 {
659 tx_state_t *tx = &dp->dp_tx;
660
661 ASSERT(!dsl_pool_config_held(dp));
662
663 mutex_enter(&tx->tx_sync_lock);
664 if (tx->tx_syncing_txg == 0 &&
665 tx->tx_quiesce_txg_waiting <= tx->tx_open_txg &&
666 tx->tx_sync_txg_waiting <= tx->tx_synced_txg &&
667 tx->tx_quiesced_txg <= tx->tx_synced_txg) {
668 tx->tx_quiesce_txg_waiting = tx->tx_open_txg + 1;
669 cv_broadcast(&tx->tx_quiesce_more_cv);
670 }
671 mutex_exit(&tx->tx_sync_lock);
672 }
673
674 boolean_t
675 txg_stalled(dsl_pool_t *dp)
676 {
677 tx_state_t *tx = &dp->dp_tx;
678 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
679 }
680
681 boolean_t
682 txg_sync_waiting(dsl_pool_t *dp)
683 {
684 tx_state_t *tx = &dp->dp_tx;
685
686 return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
687 tx->tx_quiesced_txg != 0);
688 }
689
690 /*
691 * Verify that this txg is active (open, quiescing, syncing). Non-active
692 * txg's should not be manipulated.
693 */
694 void
695 txg_verify(spa_t *spa, uint64_t txg)
696 {
697 dsl_pool_t *dp = spa_get_dsl(spa);
698 if (txg <= TXG_INITIAL || txg == ZILTEST_TXG)
699 return;
700 ASSERT3U(txg, <=, dp->dp_tx.tx_open_txg);
701 ASSERT3U(txg, >=, dp->dp_tx.tx_synced_txg);
702 ASSERT3U(txg, >=, dp->dp_tx.tx_open_txg - TXG_CONCURRENT_STATES);
703 }
704
705 /*
706 * Per-txg object lists.
707 */
708 void
709 txg_list_create(txg_list_t *tl, spa_t *spa, size_t offset)
710 {
711 int t;
712
713 mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
714
715 tl->tl_offset = offset;
716 tl->tl_spa = spa;
717
718 for (t = 0; t < TXG_SIZE; t++)
719 tl->tl_head[t] = NULL;
720 }
721
722 void
723 txg_list_destroy(txg_list_t *tl)
724 {
725 int t;
726
727 for (t = 0; t < TXG_SIZE; t++)
728 ASSERT(txg_list_empty(tl, t));
729
730 mutex_destroy(&tl->tl_lock);
731 }
732
733 boolean_t
734 txg_list_empty(txg_list_t *tl, uint64_t txg)
735 {
736 txg_verify(tl->tl_spa, txg);
737 return (tl->tl_head[txg & TXG_MASK] == NULL);
738 }
739
740 /*
741 * Returns true if all txg lists are empty.
742 *
743 * Warning: this is inherently racy (an item could be added immediately
744 * after this function returns). We don't bother with the lock because
745 * it wouldn't change the semantics.
746 */
747 boolean_t
748 txg_all_lists_empty(txg_list_t *tl)
749 {
750 for (int i = 0; i < TXG_SIZE; i++) {
751 if (!txg_list_empty(tl, i)) {
752 return (B_FALSE);
753 }
754 }
755 return (B_TRUE);
756 }
757
758 /*
759 * Add an entry to the list (unless it's already on the list).
760 * Returns B_TRUE if it was actually added.
761 */
762 boolean_t
763 txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
764 {
765 int t = txg & TXG_MASK;
766 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
767 boolean_t add;
768
769 txg_verify(tl->tl_spa, txg);
770 mutex_enter(&tl->tl_lock);
771 add = (tn->tn_member[t] == 0);
772 if (add) {
773 tn->tn_member[t] = 1;
774 tn->tn_next[t] = tl->tl_head[t];
775 tl->tl_head[t] = tn;
776 }
777 mutex_exit(&tl->tl_lock);
778
779 return (add);
780 }
781
782 /*
783 * Add an entry to the end of the list, unless it's already on the list.
784 * (walks list to find end)
785 * Returns B_TRUE if it was actually added.
786 */
787 boolean_t
788 txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg)
789 {
790 int t = txg & TXG_MASK;
791 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
792 boolean_t add;
793
794 txg_verify(tl->tl_spa, txg);
795 mutex_enter(&tl->tl_lock);
796 add = (tn->tn_member[t] == 0);
797 if (add) {
798 txg_node_t **tp;
799
800 for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t])
801 continue;
802
803 tn->tn_member[t] = 1;
804 tn->tn_next[t] = NULL;
805 *tp = tn;
806 }
807 mutex_exit(&tl->tl_lock);
808
809 return (add);
810 }
811
812 /*
813 * Remove the head of the list and return it.
814 */
815 void *
816 txg_list_remove(txg_list_t *tl, uint64_t txg)
817 {
818 int t = txg & TXG_MASK;
819 txg_node_t *tn;
820 void *p = NULL;
821
822 txg_verify(tl->tl_spa, txg);
823 mutex_enter(&tl->tl_lock);
824 if ((tn = tl->tl_head[t]) != NULL) {
825 ASSERT(tn->tn_member[t]);
826 ASSERT(tn->tn_next[t] == NULL || tn->tn_next[t]->tn_member[t]);
827 p = (char *)tn - tl->tl_offset;
828 tl->tl_head[t] = tn->tn_next[t];
829 tn->tn_next[t] = NULL;
830 tn->tn_member[t] = 0;
831 }
832 mutex_exit(&tl->tl_lock);
833
834 return (p);
835 }
836
837 /*
838 * Remove a specific item from the list and return it.
839 */
840 void *
841 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
842 {
843 int t = txg & TXG_MASK;
844 txg_node_t *tn, **tp;
845
846 txg_verify(tl->tl_spa, txg);
847 mutex_enter(&tl->tl_lock);
848
849 for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
850 if ((char *)tn - tl->tl_offset == p) {
851 *tp = tn->tn_next[t];
852 tn->tn_next[t] = NULL;
853 tn->tn_member[t] = 0;
854 mutex_exit(&tl->tl_lock);
855 return (p);
856 }
857 }
858
859 mutex_exit(&tl->tl_lock);
860
861 return (NULL);
862 }
863
864 boolean_t
865 txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
866 {
867 int t = txg & TXG_MASK;
868 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
869
870 txg_verify(tl->tl_spa, txg);
871 return (tn->tn_member[t] != 0);
872 }
873
874 /*
875 * Walk a txg list -- only safe if you know it's not changing.
876 */
877 void *
878 txg_list_head(txg_list_t *tl, uint64_t txg)
879 {
880 int t = txg & TXG_MASK;
881 txg_node_t *tn = tl->tl_head[t];
882
883 txg_verify(tl->tl_spa, txg);
884 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
885 }
886
887 void *
888 txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
889 {
890 int t = txg & TXG_MASK;
891 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
892
893 txg_verify(tl->tl_spa, txg);
894 tn = tn->tn_next[t];
895
896 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
897 }