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,
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++) {
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 */
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
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 ||
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;
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);
|
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 * Copyright 2016 Nexenta Systems, Inc. All rights reserved.
26 */
27
28 #include <sys/zfs_context.h>
29 #include <sys/txg_impl.h>
30 #include <sys/dmu_impl.h>
31 #include <sys/dmu_tx.h>
32 #include <sys/dsl_pool.h>
33 #include <sys/dsl_scan.h>
34 #include <sys/zil.h>
35 #include <sys/callb.h>
36
37 /*
38 * ZFS Transaction Groups
39 * ----------------------
40 *
41 * ZFS transaction groups are, as the name implies, groups of transactions
42 * that act on persistent state. ZFS asserts consistency at the granularity of
43 * these transaction groups. Each successive transaction group (txg) is
44 * assigned a 64-bit consecutive identifier. There are three active
45 * transaction group states: open, quiescing, or syncing. At any given time,
88 *
89 * To ensure convergence, after a certain number of passes ZFS begins
90 * overwriting locations on stable storage that had been allocated earlier in
91 * the syncing state (and subsequently freed). ZFS usually allocates new
92 * blocks to optimize for large, continuous, writes. For the syncing state to
93 * converge however it must complete a pass where no new blocks are allocated
94 * since each allocation requires a modification of persistent metadata.
95 * Further, to hasten convergence, after a prescribed number of passes, ZFS
96 * also defers frees, and stops compressing.
97 *
98 * In addition to writing out user data, we must also execute synctasks during
99 * the syncing context. A synctask is the mechanism by which some
100 * administrative activities work such as creating and destroying snapshots or
101 * datasets. Note that when a synctask is initiated it enters the open txg,
102 * and ZFS then pushes that txg as quickly as possible to completion of the
103 * syncing state in order to reduce the latency of the administrative
104 * activity. To complete the syncing state, ZFS writes out a new uberblock,
105 * the root of the tree of blocks that comprise all state stored on the ZFS
106 * pool. Finally, if there is a quiesced txg waiting, we signal that it can
107 * now transition to the syncing state.
108 *
109 * It is possible to register a callback for a TX, so the callback will be
110 * called after sync of the corresponding TX-group to disk.
111 * Required callback and its optional argument can registered by using
112 * dmu_tx_callback_register().
113 * All callback are executed async via taskq (see txg_dispatch_callbacks).
114 * There are 2 possible cases when a registered callback is called:
115 * 1) the corresponding TX is commited to disk (the first arg is 0)
116 * 2) the corresponding TX is aborted (the first arg is ECANCELED)
117 */
118
119 static void txg_sync_thread(void *arg);
120 static void txg_quiesce_thread(void *arg);
121
122 int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */
123
124 /*
125 * Prepare the txg subsystem.
126 */
127 void
128 txg_init(dsl_pool_t *dp, uint64_t txg)
129 {
130 tx_state_t *tx = &dp->dp_tx;
131 int c;
132 bzero(tx, sizeof (tx_state_t));
133
134 tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
135
136 for (c = 0; c < max_ncpus; c++) {
322 void
323 txg_rele_to_quiesce(txg_handle_t *th)
324 {
325 tx_cpu_t *tc = th->th_cpu;
326
327 ASSERT(!MUTEX_HELD(&tc->tc_lock));
328 mutex_exit(&tc->tc_open_lock);
329 }
330
331 void
332 txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
333 {
334 tx_cpu_t *tc = th->th_cpu;
335 int g = th->th_txg & TXG_MASK;
336
337 mutex_enter(&tc->tc_lock);
338 list_move_tail(&tc->tc_callbacks[g], tx_callbacks);
339 mutex_exit(&tc->tc_lock);
340 }
341
342 /* This register function can be called only from sync-context */
343 void
344 txg_register_callbacks_sync(dsl_pool_t *dp, uint64_t txg, list_t *tx_callbacks)
345 {
346 tx_state_t *tx = &dp->dp_tx;
347 tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
348 txg_handle_t th;
349
350 VERIFY3U(tx->tx_syncing_txg, ==, txg);
351
352 th.th_cpu = tc;
353 th.th_txg = txg;
354
355 txg_register_callbacks(&th, tx_callbacks);
356 }
357
358 void
359 txg_rele_to_sync(txg_handle_t *th)
360 {
361 tx_cpu_t *tc = th->th_cpu;
362 int g = th->th_txg & TXG_MASK;
363
364 mutex_enter(&tc->tc_lock);
365 ASSERT(tc->tc_count[g] != 0);
366 if (--tc->tc_count[g] == 0)
367 cv_broadcast(&tc->tc_cv[g]);
368 mutex_exit(&tc->tc_lock);
369
370 th->th_cpu = NULL; /* defensive */
371 }
372
373 /*
374 * Blocks until all transactions in the group are committed.
375 *
376 * On return, the transaction group has reached a stable state in which it can
377 * then be passed off to the syncing context.
378 */
453 if (tx->tx_commit_cb_taskq == NULL) {
454 /*
455 * Commit callback taskq hasn't been created yet.
456 */
457 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
458 max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
459 TASKQ_PREPOPULATE);
460 }
461
462 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
463 list_create(cb_list, sizeof (dmu_tx_callback_t),
464 offsetof(dmu_tx_callback_t, dcb_node));
465
466 list_move_tail(cb_list, &tc->tc_callbacks[g]);
467
468 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
469 txg_do_callbacks, cb_list, TQ_SLEEP);
470 }
471 }
472
473 static boolean_t
474 txg_is_syncing(dsl_pool_t *dp)
475 {
476 tx_state_t *tx = &dp->dp_tx;
477 ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
478 return (tx->tx_syncing_txg != 0);
479 }
480
481 static boolean_t
482 txg_is_quiescing(dsl_pool_t *dp)
483 {
484 tx_state_t *tx = &dp->dp_tx;
485 ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
486 return (tx->tx_quiescing_txg != 0);
487 }
488
489 static boolean_t
490 txg_has_quiesced_to_sync(dsl_pool_t *dp)
491 {
492 tx_state_t *tx = &dp->dp_tx;
493 ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
494 return (tx->tx_quiesced_txg != 0);
495 }
496
497 static void
498 txg_sync_thread(void *arg)
499 {
500 dsl_pool_t *dp = arg;
501 spa_t *spa = dp->dp_spa;
502 tx_state_t *tx = &dp->dp_tx;
503 callb_cpr_t cpr;
504 uint64_t start, delta;
505
506 txg_thread_enter(tx, &cpr);
507
508 start = delta = 0;
509 for (;;) {
510 uint64_t timeout = zfs_txg_timeout * hz;
511 uint64_t timer;
512 uint64_t txg;
513
514 /*
515 * We sync when we're scanning, there's someone waiting
516 * on us, or the quiesce thread has handed off a txg to
517 * us, or we have reached our timeout.
518 */
519 timer = (delta >= timeout ? 0 : timeout - delta);
520 while (!dsl_scan_active(dp->dp_scan) &&
521 !tx->tx_exiting && timer > 0 &&
522 tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
523 !txg_has_quiesced_to_sync(dp) &&
524 dp->dp_dirty_total < zfs_dirty_data_sync) {
525 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
526 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
527 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
528 delta = ddi_get_lbolt() - start;
529 timer = (delta > timeout ? 0 : timeout - delta);
530 }
531
532 /*
533 * Wait until the quiesce thread hands off a txg to us,
534 * prompting it to do so if necessary.
535 */
536 while (!tx->tx_exiting && !txg_has_quiesced_to_sync(dp)) {
537 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
538 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
539 cv_broadcast(&tx->tx_quiesce_more_cv);
540 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
541 }
542
543 if (tx->tx_exiting)
544 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
545
546 /*
547 * Consume the quiesced txg which has been handed off to
548 * us. This may cause the quiescing thread to now be
549 * able to quiesce another txg, so we must signal it.
550 */
551 ASSERT(tx->tx_quiesced_txg != 0);
552 txg = tx->tx_quiesced_txg;
553 tx->tx_quiesced_txg = 0;
554 tx->tx_syncing_txg = txg;
555 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
556 cv_broadcast(&tx->tx_quiesce_more_cv);
557
558 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
559 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
560 mutex_exit(&tx->tx_sync_lock);
561
562 start = ddi_get_lbolt();
563 spa_sync(spa, txg);
564 delta = ddi_get_lbolt() - start;
565
566 mutex_enter(&tx->tx_sync_lock);
567 tx->tx_synced_txg = txg;
568 tx->tx_syncing_txg = 0;
569 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
570 cv_broadcast(&tx->tx_sync_done_cv);
571
580 txg_quiesce_thread(void *arg)
581 {
582 dsl_pool_t *dp = arg;
583 tx_state_t *tx = &dp->dp_tx;
584 callb_cpr_t cpr;
585
586 txg_thread_enter(tx, &cpr);
587
588 for (;;) {
589 uint64_t txg;
590
591 /*
592 * We quiesce when there's someone waiting on us.
593 * However, we can only have one txg in "quiescing" or
594 * "quiesced, waiting to sync" state. So we wait until
595 * the "quiesced, waiting to sync" txg has been consumed
596 * by the sync thread.
597 */
598 while (!tx->tx_exiting &&
599 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
600 txg_has_quiesced_to_sync(dp)))
601 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
602
603 if (tx->tx_exiting)
604 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
605
606 txg = tx->tx_open_txg;
607 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
608 txg, tx->tx_quiesce_txg_waiting,
609 tx->tx_sync_txg_waiting);
610 tx->tx_quiescing_txg = txg;
611
612 mutex_exit(&tx->tx_sync_lock);
613 txg_quiesce(dp, txg);
614 mutex_enter(&tx->tx_sync_lock);
615
616 /*
617 * Hand this txg off to the sync thread.
618 */
619 dprintf("quiesce done, handing off txg %llu\n", txg);
620 tx->tx_quiescing_txg = 0;
621 tx->tx_quiesced_txg = txg;
622 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
623 cv_broadcast(&tx->tx_sync_more_cv);
624 cv_broadcast(&tx->tx_quiesce_done_cv);
625 }
626 }
627
628 /*
629 * Delay this thread by delay nanoseconds if we are still in the open
630 * transaction group and there is already a waiting txg quiescing or quiesced.
631 * Abort the delay if this txg stalls or enters the quiescing state.
632 */
633 void
634 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
635 {
636 tx_state_t *tx = &dp->dp_tx;
637 hrtime_t start = gethrtime();
638
639 /* don't delay if this txg could transition to quiescing immediately */
640 if (tx->tx_open_txg > txg ||
698 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
699 while (tx->tx_open_txg < txg) {
700 cv_broadcast(&tx->tx_quiesce_more_cv);
701 cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
702 }
703 mutex_exit(&tx->tx_sync_lock);
704 }
705
706 /*
707 * If there isn't a txg syncing or in the pipeline, push another txg through
708 * the pipeline by queiscing the open txg.
709 */
710 void
711 txg_kick(dsl_pool_t *dp)
712 {
713 tx_state_t *tx = &dp->dp_tx;
714
715 ASSERT(!dsl_pool_config_held(dp));
716
717 mutex_enter(&tx->tx_sync_lock);
718 if (!txg_is_syncing(dp) &&
719 !txg_is_quiescing(dp) &&
720 tx->tx_quiesce_txg_waiting <= tx->tx_open_txg &&
721 tx->tx_sync_txg_waiting <= tx->tx_synced_txg &&
722 tx->tx_quiesced_txg <= tx->tx_synced_txg) {
723 tx->tx_quiesce_txg_waiting = tx->tx_open_txg + 1;
724 cv_broadcast(&tx->tx_quiesce_more_cv);
725 }
726 mutex_exit(&tx->tx_sync_lock);
727 }
728
729 boolean_t
730 txg_stalled(dsl_pool_t *dp)
731 {
732 tx_state_t *tx = &dp->dp_tx;
733 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
734 }
735
736 boolean_t
737 txg_sync_waiting(dsl_pool_t *dp)
738 {
739 tx_state_t *tx = &dp->dp_tx;
860 *tp = tn;
861 }
862 mutex_exit(&tl->tl_lock);
863
864 return (add);
865 }
866
867 /*
868 * Remove the head of the list and return it.
869 */
870 void *
871 txg_list_remove(txg_list_t *tl, uint64_t txg)
872 {
873 int t = txg & TXG_MASK;
874 txg_node_t *tn;
875 void *p = NULL;
876
877 txg_verify(tl->tl_spa, txg);
878 mutex_enter(&tl->tl_lock);
879 if ((tn = tl->tl_head[t]) != NULL) {
880 p = (char *)tn - tl->tl_offset;
881 tl->tl_head[t] = tn->tn_next[t];
882 tn->tn_next[t] = NULL;
883 tn->tn_member[t] = 0;
884 }
885 mutex_exit(&tl->tl_lock);
886
887 return (p);
888 }
889
890 /*
891 * Remove a specific item from the list and return it.
892 */
893 void *
894 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
895 {
896 int t = txg & TXG_MASK;
897 txg_node_t *tn, **tp;
898
899 txg_verify(tl->tl_spa, txg);
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