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.
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.
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]
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Portions Copyright 2011 Martin Matuska
24 * Copyright (c) 2012, 2019 by Delphix. All rights reserved.
27 #include <sys/zfs_context.h>
28 #include <sys/txg_impl.h>
29 #include <sys/dmu_impl.h>
30 #include <sys/spa_impl.h>
31 #include <sys/dmu_tx.h>
32 #include <sys/dsl_pool.h>
33 #include <sys/dsl_scan.h>
35 #include <sys/callb.h>
36 #include <sys/trace_txg.h>
39 * ZFS Transaction Groups
40 * ----------------------
42 * ZFS transaction groups are, as the name implies, groups of transactions
43 * that act on persistent state. ZFS asserts consistency at the granularity of
44 * these transaction groups. Each successive transaction group (txg) is
45 * assigned a 64-bit consecutive identifier. There are three active
46 * transaction group states: open, quiescing, or syncing. At any given time,
47 * there may be an active txg associated with each state; each active txg may
48 * either be processing, or blocked waiting to enter the next state. There may
49 * be up to three active txgs, and there is always a txg in the open state
50 * (though it may be blocked waiting to enter the quiescing state). In broad
51 * strokes, transactions -- operations that change in-memory structures -- are
52 * accepted into the txg in the open state, and are completed while the txg is
53 * in the open or quiescing states. The accumulated changes are written to
54 * disk in the syncing state.
58 * When a new txg becomes active, it first enters the open state. New
59 * transactions -- updates to in-memory structures -- are assigned to the
60 * currently open txg. There is always a txg in the open state so that ZFS can
61 * accept new changes (though the txg may refuse new changes if it has hit
62 * some limit). ZFS advances the open txg to the next state for a variety of
63 * reasons such as it hitting a time or size threshold, or the execution of an
64 * administrative action that must be completed in the syncing state.
68 * After a txg exits the open state, it enters the quiescing state. The
69 * quiescing state is intended to provide a buffer between accepting new
70 * transactions in the open state and writing them out to stable storage in
71 * the syncing state. While quiescing, transactions can continue their
72 * operation without delaying either of the other states. Typically, a txg is
73 * in the quiescing state very briefly since the operations are bounded by
74 * software latencies rather than, say, slower I/O latencies. After all
75 * transactions complete, the txg is ready to enter the next state.
79 * In the syncing state, the in-memory state built up during the open and (to
80 * a lesser degree) the quiescing states is written to stable storage. The
81 * process of writing out modified data can, in turn modify more data. For
82 * example when we write new blocks, we need to allocate space for them; those
83 * allocations modify metadata (space maps)... which themselves must be
84 * written to stable storage. During the sync state, ZFS iterates, writing out
85 * data until it converges and all in-memory changes have been written out.
86 * The first such pass is the largest as it encompasses all the modified user
87 * data (as opposed to filesystem metadata). Subsequent passes typically have
88 * far less data to write as they consist exclusively of filesystem metadata.
90 * To ensure convergence, after a certain number of passes ZFS begins
91 * overwriting locations on stable storage that had been allocated earlier in
92 * the syncing state (and subsequently freed). ZFS usually allocates new
93 * blocks to optimize for large, continuous, writes. For the syncing state to
94 * converge however it must complete a pass where no new blocks are allocated
95 * since each allocation requires a modification of persistent metadata.
96 * Further, to hasten convergence, after a prescribed number of passes, ZFS
97 * also defers frees, and stops compressing.
99 * In addition to writing out user data, we must also execute synctasks during
100 * the syncing context. A synctask is the mechanism by which some
101 * administrative activities work such as creating and destroying snapshots or
102 * datasets. Note that when a synctask is initiated it enters the open txg,
103 * and ZFS then pushes that txg as quickly as possible to completion of the
104 * syncing state in order to reduce the latency of the administrative
105 * activity. To complete the syncing state, ZFS writes out a new uberblock,
106 * the root of the tree of blocks that comprise all state stored on the ZFS
107 * pool. Finally, if there is a quiesced txg waiting, we signal that it can
108 * now transition to the syncing state.
111 static void txg_sync_thread(void *arg);
112 static void txg_quiesce_thread(void *arg);
114 int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */
117 * Prepare the txg subsystem.
120 txg_init(dsl_pool_t *dp, uint64_t txg)
122 tx_state_t *tx = &dp->dp_tx;
124 bzero(tx, sizeof (tx_state_t));
126 tx->tx_cpu = vmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
128 for (c = 0; c < max_ncpus; c++) {
131 mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
132 mutex_init(&tx->tx_cpu[c].tc_open_lock, NULL, MUTEX_NOLOCKDEP,
134 for (i = 0; i < TXG_SIZE; i++) {
135 cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
137 list_create(&tx->tx_cpu[c].tc_callbacks[i],
138 sizeof (dmu_tx_callback_t),
139 offsetof(dmu_tx_callback_t, dcb_node));
143 mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);
145 cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
146 cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
147 cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
148 cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
149 cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);
151 tx->tx_open_txg = txg;
155 * Close down the txg subsystem.
158 txg_fini(dsl_pool_t *dp)
160 tx_state_t *tx = &dp->dp_tx;
163 ASSERT0(tx->tx_threads);
165 mutex_destroy(&tx->tx_sync_lock);
167 cv_destroy(&tx->tx_sync_more_cv);
168 cv_destroy(&tx->tx_sync_done_cv);
169 cv_destroy(&tx->tx_quiesce_more_cv);
170 cv_destroy(&tx->tx_quiesce_done_cv);
171 cv_destroy(&tx->tx_exit_cv);
173 for (c = 0; c < max_ncpus; c++) {
176 mutex_destroy(&tx->tx_cpu[c].tc_open_lock);
177 mutex_destroy(&tx->tx_cpu[c].tc_lock);
178 for (i = 0; i < TXG_SIZE; i++) {
179 cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
180 list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
184 if (tx->tx_commit_cb_taskq != NULL)
185 taskq_destroy(tx->tx_commit_cb_taskq);
187 vmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
189 bzero(tx, sizeof (tx_state_t));
193 * Start syncing transaction groups.
196 txg_sync_start(dsl_pool_t *dp)
198 tx_state_t *tx = &dp->dp_tx;
200 mutex_enter(&tx->tx_sync_lock);
202 dprintf("pool %p\n", dp);
204 ASSERT0(tx->tx_threads);
208 tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
209 dp, 0, &p0, TS_RUN, defclsyspri);
212 * The sync thread can need a larger-than-default stack size on
213 * 32-bit x86. This is due in part to nested pools and
214 * scrub_visitbp() recursion.
216 tx->tx_sync_thread = thread_create(NULL, 0, txg_sync_thread,
217 dp, 0, &p0, TS_RUN, defclsyspri);
219 mutex_exit(&tx->tx_sync_lock);
223 txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr)
225 CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
226 mutex_enter(&tx->tx_sync_lock);
230 txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp)
232 ASSERT(*tpp != NULL);
235 cv_broadcast(&tx->tx_exit_cv);
236 CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */
241 txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time)
243 CALLB_CPR_SAFE_BEGIN(cpr);
246 * cv_wait_sig() is used instead of cv_wait() in order to prevent
247 * this process from incorrectly contributing to the system load
251 (void) cv_timedwait_sig(cv, &tx->tx_sync_lock,
252 ddi_get_lbolt() + time);
254 cv_wait_sig(cv, &tx->tx_sync_lock);
257 CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
261 * Stop syncing transaction groups.
264 txg_sync_stop(dsl_pool_t *dp)
266 tx_state_t *tx = &dp->dp_tx;
268 dprintf("pool %p\n", dp);
270 * Finish off any work in progress.
272 ASSERT3U(tx->tx_threads, ==, 2);
275 * We need to ensure that we've vacated the deferred metaslab trees.
277 txg_wait_synced(dp, tx->tx_open_txg + TXG_DEFER_SIZE);
280 * Wake all sync threads and wait for them to die.
282 mutex_enter(&tx->tx_sync_lock);
284 ASSERT3U(tx->tx_threads, ==, 2);
288 cv_broadcast(&tx->tx_quiesce_more_cv);
289 cv_broadcast(&tx->tx_quiesce_done_cv);
290 cv_broadcast(&tx->tx_sync_more_cv);
292 while (tx->tx_threads != 0)
293 cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);
297 mutex_exit(&tx->tx_sync_lock);
301 txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
303 tx_state_t *tx = &dp->dp_tx;
308 * It appears the processor id is simply used as a "random"
309 * number to index into the array, and there isn't any other
310 * significance to the chosen tx_cpu. Because.. Why not use
311 * the current cpu to index into the array?
314 tc = &tx->tx_cpu[CPU_SEQID];
317 mutex_enter(&tc->tc_open_lock);
318 txg = tx->tx_open_txg;
320 mutex_enter(&tc->tc_lock);
321 tc->tc_count[txg & TXG_MASK]++;
322 mutex_exit(&tc->tc_lock);
331 txg_rele_to_quiesce(txg_handle_t *th)
333 tx_cpu_t *tc = th->th_cpu;
335 ASSERT(!MUTEX_HELD(&tc->tc_lock));
336 mutex_exit(&tc->tc_open_lock);
340 txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
342 tx_cpu_t *tc = th->th_cpu;
343 int g = th->th_txg & TXG_MASK;
345 mutex_enter(&tc->tc_lock);
346 list_move_tail(&tc->tc_callbacks[g], tx_callbacks);
347 mutex_exit(&tc->tc_lock);
351 txg_rele_to_sync(txg_handle_t *th)
353 tx_cpu_t *tc = th->th_cpu;
354 int g = th->th_txg & TXG_MASK;
356 mutex_enter(&tc->tc_lock);
357 ASSERT(tc->tc_count[g] != 0);
358 if (--tc->tc_count[g] == 0)
359 cv_broadcast(&tc->tc_cv[g]);
360 mutex_exit(&tc->tc_lock);
362 th->th_cpu = NULL; /* defensive */
366 * Blocks until all transactions in the group are committed.
368 * On return, the transaction group has reached a stable state in which it can
369 * then be passed off to the syncing context.
372 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
374 tx_state_t *tx = &dp->dp_tx;
375 uint64_t tx_open_time;
376 int g = txg & TXG_MASK;
380 * Grab all tc_open_locks so nobody else can get into this txg.
382 for (c = 0; c < max_ncpus; c++)
383 mutex_enter(&tx->tx_cpu[c].tc_open_lock);
385 ASSERT(txg == tx->tx_open_txg);
387 tx->tx_open_time = tx_open_time = gethrtime();
389 DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg);
390 DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg);
393 * Now that we've incremented tx_open_txg, we can let threads
394 * enter the next transaction group.
396 for (c = 0; c < max_ncpus; c++)
397 mutex_exit(&tx->tx_cpu[c].tc_open_lock);
399 spa_txg_history_set(dp->dp_spa, txg, TXG_STATE_OPEN, tx_open_time);
400 spa_txg_history_add(dp->dp_spa, txg + 1, tx_open_time);
403 * Quiesce the transaction group by waiting for everyone to txg_exit().
405 for (c = 0; c < max_ncpus; c++) {
406 tx_cpu_t *tc = &tx->tx_cpu[c];
407 mutex_enter(&tc->tc_lock);
408 while (tc->tc_count[g] != 0)
409 cv_wait(&tc->tc_cv[g], &tc->tc_lock);
410 mutex_exit(&tc->tc_lock);
413 spa_txg_history_set(dp->dp_spa, txg, TXG_STATE_QUIESCED, gethrtime());
417 txg_do_callbacks(list_t *cb_list)
419 dmu_tx_do_callbacks(cb_list, 0);
421 list_destroy(cb_list);
423 kmem_free(cb_list, sizeof (list_t));
427 * Dispatch the commit callbacks registered on this txg to worker threads.
429 * If no callbacks are registered for a given TXG, nothing happens.
430 * This function creates a taskq for the associated pool, if needed.
433 txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
436 tx_state_t *tx = &dp->dp_tx;
439 for (c = 0; c < max_ncpus; c++) {
440 tx_cpu_t *tc = &tx->tx_cpu[c];
442 * No need to lock tx_cpu_t at this point, since this can
443 * only be called once a txg has been synced.
446 int g = txg & TXG_MASK;
448 if (list_is_empty(&tc->tc_callbacks[g]))
451 if (tx->tx_commit_cb_taskq == NULL) {
453 * Commit callback taskq hasn't been created yet.
455 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
456 max_ncpus, defclsyspri, max_ncpus, max_ncpus * 2,
457 TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
460 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
461 list_create(cb_list, sizeof (dmu_tx_callback_t),
462 offsetof(dmu_tx_callback_t, dcb_node));
464 list_move_tail(cb_list, &tc->tc_callbacks[g]);
466 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
467 txg_do_callbacks, cb_list, TQ_SLEEP);
472 * Wait for pending commit callbacks of already-synced transactions to finish
474 * Calling this function from within a commit callback will deadlock.
477 txg_wait_callbacks(dsl_pool_t *dp)
479 tx_state_t *tx = &dp->dp_tx;
481 if (tx->tx_commit_cb_taskq != NULL)
482 taskq_wait_outstanding(tx->tx_commit_cb_taskq, 0);
486 txg_is_syncing(dsl_pool_t *dp)
488 tx_state_t *tx = &dp->dp_tx;
489 ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
490 return (tx->tx_syncing_txg != 0);
494 txg_is_quiescing(dsl_pool_t *dp)
496 tx_state_t *tx = &dp->dp_tx;
497 ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
498 return (tx->tx_quiescing_txg != 0);
502 txg_has_quiesced_to_sync(dsl_pool_t *dp)
504 tx_state_t *tx = &dp->dp_tx;
505 ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
506 return (tx->tx_quiesced_txg != 0);
510 txg_sync_thread(void *arg)
512 dsl_pool_t *dp = arg;
513 spa_t *spa = dp->dp_spa;
514 tx_state_t *tx = &dp->dp_tx;
516 clock_t start, delta;
518 (void) spl_fstrans_mark();
519 txg_thread_enter(tx, &cpr);
523 clock_t timeout = zfs_txg_timeout * hz;
526 uint64_t dirty_min_bytes =
527 zfs_dirty_data_max * zfs_dirty_data_sync_percent / 100;
530 * We sync when we're scanning, there's someone waiting
531 * on us, or the quiesce thread has handed off a txg to
532 * us, or we have reached our timeout.
534 timer = (delta >= timeout ? 0 : timeout - delta);
535 while (!dsl_scan_active(dp->dp_scan) &&
536 !tx->tx_exiting && timer > 0 &&
537 tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
538 !txg_has_quiesced_to_sync(dp) &&
539 dp->dp_dirty_total < dirty_min_bytes) {
540 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
541 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
542 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
543 delta = ddi_get_lbolt() - start;
544 timer = (delta > timeout ? 0 : timeout - delta);
548 * Wait until the quiesce thread hands off a txg to us,
549 * prompting it to do so if necessary.
551 while (!tx->tx_exiting && !txg_has_quiesced_to_sync(dp)) {
552 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
553 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
554 cv_broadcast(&tx->tx_quiesce_more_cv);
555 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
559 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
562 * Consume the quiesced txg which has been handed off to
563 * us. This may cause the quiescing thread to now be
564 * able to quiesce another txg, so we must signal it.
566 ASSERT(tx->tx_quiesced_txg != 0);
567 txg = tx->tx_quiesced_txg;
568 tx->tx_quiesced_txg = 0;
569 tx->tx_syncing_txg = txg;
570 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
571 cv_broadcast(&tx->tx_quiesce_more_cv);
573 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
574 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
575 mutex_exit(&tx->tx_sync_lock);
577 txg_stat_t *ts = spa_txg_history_init_io(spa, txg, dp);
578 start = ddi_get_lbolt();
580 delta = ddi_get_lbolt() - start;
581 spa_txg_history_fini_io(spa, ts);
583 mutex_enter(&tx->tx_sync_lock);
584 tx->tx_synced_txg = txg;
585 tx->tx_syncing_txg = 0;
586 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
587 cv_broadcast(&tx->tx_sync_done_cv);
590 * Dispatch commit callbacks to worker threads.
592 txg_dispatch_callbacks(dp, txg);
597 txg_quiesce_thread(void *arg)
599 dsl_pool_t *dp = arg;
600 tx_state_t *tx = &dp->dp_tx;
603 txg_thread_enter(tx, &cpr);
609 * We quiesce when there's someone waiting on us.
610 * However, we can only have one txg in "quiescing" or
611 * "quiesced, waiting to sync" state. So we wait until
612 * the "quiesced, waiting to sync" txg has been consumed
613 * by the sync thread.
615 while (!tx->tx_exiting &&
616 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
617 txg_has_quiesced_to_sync(dp)))
618 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
621 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
623 txg = tx->tx_open_txg;
624 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
625 txg, tx->tx_quiesce_txg_waiting,
626 tx->tx_sync_txg_waiting);
627 tx->tx_quiescing_txg = txg;
629 mutex_exit(&tx->tx_sync_lock);
630 txg_quiesce(dp, txg);
631 mutex_enter(&tx->tx_sync_lock);
634 * Hand this txg off to the sync thread.
636 dprintf("quiesce done, handing off txg %llu\n", txg);
637 tx->tx_quiescing_txg = 0;
638 tx->tx_quiesced_txg = txg;
639 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
640 cv_broadcast(&tx->tx_sync_more_cv);
641 cv_broadcast(&tx->tx_quiesce_done_cv);
646 * Delay this thread by delay nanoseconds if we are still in the open
647 * transaction group and there is already a waiting txg quiesing or quiesced.
648 * Abort the delay if this txg stalls or enters the quiesing state.
651 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
653 tx_state_t *tx = &dp->dp_tx;
654 hrtime_t start = gethrtime();
656 /* don't delay if this txg could transition to quiescing immediately */
657 if (tx->tx_open_txg > txg ||
658 tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
661 mutex_enter(&tx->tx_sync_lock);
662 if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
663 mutex_exit(&tx->tx_sync_lock);
667 while (gethrtime() - start < delay &&
668 tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) {
669 (void) cv_timedwait_hires(&tx->tx_quiesce_more_cv,
670 &tx->tx_sync_lock, delay, resolution, 0);
673 DMU_TX_STAT_BUMP(dmu_tx_delay);
675 mutex_exit(&tx->tx_sync_lock);
679 txg_wait_synced_impl(dsl_pool_t *dp, uint64_t txg, boolean_t wait_sig)
681 tx_state_t *tx = &dp->dp_tx;
683 ASSERT(!dsl_pool_config_held(dp));
685 mutex_enter(&tx->tx_sync_lock);
686 ASSERT3U(tx->tx_threads, ==, 2);
688 txg = tx->tx_open_txg + TXG_DEFER_SIZE;
689 if (tx->tx_sync_txg_waiting < txg)
690 tx->tx_sync_txg_waiting = txg;
691 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
692 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
693 while (tx->tx_synced_txg < txg) {
694 dprintf("broadcasting sync more "
695 "tx_synced=%llu waiting=%llu dp=%px\n",
696 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
697 cv_broadcast(&tx->tx_sync_more_cv);
700 * Condition wait here but stop if the thread receives a
701 * signal. The caller may call txg_wait_synced*() again
702 * to resume waiting for this txg.
704 if (cv_wait_io_sig(&tx->tx_sync_done_cv,
705 &tx->tx_sync_lock) == 0) {
706 mutex_exit(&tx->tx_sync_lock);
710 cv_wait_io(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
713 mutex_exit(&tx->tx_sync_lock);
718 txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
720 VERIFY0(txg_wait_synced_impl(dp, txg, B_FALSE));
724 * Similar to a txg_wait_synced but it can be interrupted from a signal.
725 * Returns B_TRUE if the thread was signaled while waiting.
728 txg_wait_synced_sig(dsl_pool_t *dp, uint64_t txg)
730 return (txg_wait_synced_impl(dp, txg, B_TRUE));
734 * Wait for the specified open transaction group. Set should_quiesce
735 * when the current open txg should be quiesced immediately.
738 txg_wait_open(dsl_pool_t *dp, uint64_t txg, boolean_t should_quiesce)
740 tx_state_t *tx = &dp->dp_tx;
742 ASSERT(!dsl_pool_config_held(dp));
744 mutex_enter(&tx->tx_sync_lock);
745 ASSERT3U(tx->tx_threads, ==, 2);
747 txg = tx->tx_open_txg + 1;
748 if (tx->tx_quiesce_txg_waiting < txg && should_quiesce)
749 tx->tx_quiesce_txg_waiting = txg;
750 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
751 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
752 while (tx->tx_open_txg < txg) {
753 cv_broadcast(&tx->tx_quiesce_more_cv);
755 * Callers setting should_quiesce will use cv_wait_io() and
756 * be accounted for as iowait time. Otherwise, the caller is
757 * understood to be idle and cv_wait_sig() is used to prevent
758 * incorrectly inflating the system load average.
760 if (should_quiesce == B_TRUE) {
761 cv_wait_io(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
763 cv_wait_sig(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
766 mutex_exit(&tx->tx_sync_lock);
770 * If there isn't a txg syncing or in the pipeline, push another txg through
771 * the pipeline by queiscing the open txg.
774 txg_kick(dsl_pool_t *dp)
776 tx_state_t *tx = &dp->dp_tx;
778 ASSERT(!dsl_pool_config_held(dp));
780 mutex_enter(&tx->tx_sync_lock);
781 if (!txg_is_syncing(dp) &&
782 !txg_is_quiescing(dp) &&
783 tx->tx_quiesce_txg_waiting <= tx->tx_open_txg &&
784 tx->tx_sync_txg_waiting <= tx->tx_synced_txg &&
785 tx->tx_quiesced_txg <= tx->tx_synced_txg) {
786 tx->tx_quiesce_txg_waiting = tx->tx_open_txg + 1;
787 cv_broadcast(&tx->tx_quiesce_more_cv);
789 mutex_exit(&tx->tx_sync_lock);
793 txg_stalled(dsl_pool_t *dp)
795 tx_state_t *tx = &dp->dp_tx;
796 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
800 txg_sync_waiting(dsl_pool_t *dp)
802 tx_state_t *tx = &dp->dp_tx;
804 return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
805 tx->tx_quiesced_txg != 0);
809 * Verify that this txg is active (open, quiescing, syncing). Non-active
810 * txg's should not be manipulated.
814 txg_verify(spa_t *spa, uint64_t txg)
816 ASSERTV(dsl_pool_t *dp = spa_get_dsl(spa));
817 if (txg <= TXG_INITIAL || txg == ZILTEST_TXG)
819 ASSERT3U(txg, <=, dp->dp_tx.tx_open_txg);
820 ASSERT3U(txg, >=, dp->dp_tx.tx_synced_txg);
821 ASSERT3U(txg, >=, dp->dp_tx.tx_open_txg - TXG_CONCURRENT_STATES);
826 * Per-txg object lists.
829 txg_list_create(txg_list_t *tl, spa_t *spa, size_t offset)
833 mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
835 tl->tl_offset = offset;
838 for (t = 0; t < TXG_SIZE; t++)
839 tl->tl_head[t] = NULL;
843 txg_list_empty_impl(txg_list_t *tl, uint64_t txg)
845 ASSERT(MUTEX_HELD(&tl->tl_lock));
846 TXG_VERIFY(tl->tl_spa, txg);
847 return (tl->tl_head[txg & TXG_MASK] == NULL);
851 txg_list_empty(txg_list_t *tl, uint64_t txg)
853 mutex_enter(&tl->tl_lock);
854 boolean_t ret = txg_list_empty_impl(tl, txg);
855 mutex_exit(&tl->tl_lock);
861 txg_list_destroy(txg_list_t *tl)
865 mutex_enter(&tl->tl_lock);
866 for (t = 0; t < TXG_SIZE; t++)
867 ASSERT(txg_list_empty_impl(tl, t));
868 mutex_exit(&tl->tl_lock);
870 mutex_destroy(&tl->tl_lock);
874 * Returns true if all txg lists are empty.
876 * Warning: this is inherently racy (an item could be added immediately
877 * after this function returns).
880 txg_all_lists_empty(txg_list_t *tl)
882 mutex_enter(&tl->tl_lock);
883 for (int i = 0; i < TXG_SIZE; i++) {
884 if (!txg_list_empty_impl(tl, i)) {
885 mutex_exit(&tl->tl_lock);
889 mutex_exit(&tl->tl_lock);
894 * Add an entry to the list (unless it's already on the list).
895 * Returns B_TRUE if it was actually added.
898 txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
900 int t = txg & TXG_MASK;
901 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
904 TXG_VERIFY(tl->tl_spa, txg);
905 mutex_enter(&tl->tl_lock);
906 add = (tn->tn_member[t] == 0);
908 tn->tn_member[t] = 1;
909 tn->tn_next[t] = tl->tl_head[t];
912 mutex_exit(&tl->tl_lock);
918 * Add an entry to the end of the list, unless it's already on the list.
919 * (walks list to find end)
920 * Returns B_TRUE if it was actually added.
923 txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg)
925 int t = txg & TXG_MASK;
926 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
929 TXG_VERIFY(tl->tl_spa, txg);
930 mutex_enter(&tl->tl_lock);
931 add = (tn->tn_member[t] == 0);
935 for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t])
938 tn->tn_member[t] = 1;
939 tn->tn_next[t] = NULL;
942 mutex_exit(&tl->tl_lock);
948 * Remove the head of the list and return it.
951 txg_list_remove(txg_list_t *tl, uint64_t txg)
953 int t = txg & TXG_MASK;
957 TXG_VERIFY(tl->tl_spa, txg);
958 mutex_enter(&tl->tl_lock);
959 if ((tn = tl->tl_head[t]) != NULL) {
960 ASSERT(tn->tn_member[t]);
961 ASSERT(tn->tn_next[t] == NULL || tn->tn_next[t]->tn_member[t]);
962 p = (char *)tn - tl->tl_offset;
963 tl->tl_head[t] = tn->tn_next[t];
964 tn->tn_next[t] = NULL;
965 tn->tn_member[t] = 0;
967 mutex_exit(&tl->tl_lock);
973 * Remove a specific item from the list and return it.
976 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
978 int t = txg & TXG_MASK;
979 txg_node_t *tn, **tp;
981 TXG_VERIFY(tl->tl_spa, txg);
982 mutex_enter(&tl->tl_lock);
984 for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
985 if ((char *)tn - tl->tl_offset == p) {
986 *tp = tn->tn_next[t];
987 tn->tn_next[t] = NULL;
988 tn->tn_member[t] = 0;
989 mutex_exit(&tl->tl_lock);
994 mutex_exit(&tl->tl_lock);
1000 txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
1002 int t = txg & TXG_MASK;
1003 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
1005 TXG_VERIFY(tl->tl_spa, txg);
1006 return (tn->tn_member[t] != 0);
1013 txg_list_head(txg_list_t *tl, uint64_t txg)
1015 int t = txg & TXG_MASK;
1018 mutex_enter(&tl->tl_lock);
1019 tn = tl->tl_head[t];
1020 mutex_exit(&tl->tl_lock);
1022 TXG_VERIFY(tl->tl_spa, txg);
1023 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
1027 txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
1029 int t = txg & TXG_MASK;
1030 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
1032 TXG_VERIFY(tl->tl_spa, txg);
1034 mutex_enter(&tl->tl_lock);
1035 tn = tn->tn_next[t];
1036 mutex_exit(&tl->tl_lock);
1038 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
1041 #if defined(_KERNEL)
1042 EXPORT_SYMBOL(txg_init);
1043 EXPORT_SYMBOL(txg_fini);
1044 EXPORT_SYMBOL(txg_sync_start);
1045 EXPORT_SYMBOL(txg_sync_stop);
1046 EXPORT_SYMBOL(txg_hold_open);
1047 EXPORT_SYMBOL(txg_rele_to_quiesce);
1048 EXPORT_SYMBOL(txg_rele_to_sync);
1049 EXPORT_SYMBOL(txg_register_callbacks);
1050 EXPORT_SYMBOL(txg_delay);
1051 EXPORT_SYMBOL(txg_wait_synced);
1052 EXPORT_SYMBOL(txg_wait_open);
1053 EXPORT_SYMBOL(txg_wait_callbacks);
1054 EXPORT_SYMBOL(txg_stalled);
1055 EXPORT_SYMBOL(txg_sync_waiting);
1057 module_param(zfs_txg_timeout, int, 0644);
1058 MODULE_PARM_DESC(zfs_txg_timeout, "Max seconds worth of delta per txg");