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) 2013 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/callb.h>
34
35 /*
36 * ZFS Transaction Groups
37 * ----------------------
38 *
39 * ZFS transaction groups are, as the name implies, groups of transactions
40 * that act on persistent state. ZFS asserts consistency at the granularity of
41 * these transaction groups. Each successive transaction group (txg) is
42 * assigned a 64-bit consecutive identifier. There are three active
43 * transaction group states: open, quiescing, or syncing. At any given time,
44 * there may be an active txg associated with each state; each active txg may
45 * either be processing, or blocked waiting to enter the next state. There may
46 * be up to three active txgs, and there is always a txg in the open state
47 * (though it may be blocked waiting to enter the quiescing state). In broad
48 * strokes, transactions — operations that change in-memory structures — are
49 * accepted into the txg in the open state, and are completed while the txg is
50 * in the open or quiescing states. The accumulated changes are written to
51 * disk in the syncing state.
52 *
53 * Open
54 *
55 * When a new txg becomes active, it first enters the open state. New
56 * transactions — updates to in-memory structures — are assigned to the
57 * currently open txg. There is always a txg in the open state so that ZFS can
58 * accept new changes (though the txg may refuse new changes if it has hit
59 * some limit). ZFS advances the open txg to the next state for a variety of
60 * reasons such as it hitting a time or size threshold, or the execution of an
61 * administrative action that must be completed in the syncing state.
62 *
63 * Quiescing
64 *
65 * After a txg exits the open state, it enters the quiescing state. The
66 * quiescing state is intended to provide a buffer between accepting new
67 * transactions in the open state and writing them out to stable storage in
68 * the syncing state. While quiescing, transactions can continue their
69 * operation without delaying either of the other states. Typically, a txg is
70 * in the quiescing state very briefly since the operations are bounded by
71 * software latencies rather than, say, slower I/O latencies. After all
72 * transactions complete, the txg is ready to enter the next state.
73 *
74 * Syncing
75 *
76 * In the syncing state, the in-memory state built up during the open and (to
77 * a lesser degree) the quiescing states is written to stable storage. The
78 * process of writing out modified data can, in turn modify more data. For
79 * example when we write new blocks, we need to allocate space for them; those
80 * allocations modify metadata (space maps)... which themselves must be
81 * written to stable storage. During the sync state, ZFS iterates, writing out
82 * data until it converges and all in-memory changes have been written out.
83 * The first such pass is the largest as it encompasses all the modified user
84 * data (as opposed to filesystem metadata). Subsequent passes typically have
85 * far less data to write as they consist exclusively of filesystem metadata.
86 *
87 * To ensure convergence, after a certain number of passes ZFS begins
88 * overwriting locations on stable storage that had been allocated earlier in
89 * the syncing state (and subsequently freed). ZFS usually allocates new
90 * blocks to optimize for large, continuous, writes. For the syncing state to
91 * converge however it must complete a pass where no new blocks are allocated
92 * since each allocation requires a modification of persistent metadata.
93 * Further, to hasten convergence, after a prescribed number of passes, ZFS
94 * also defers frees, and stops compressing.
95 *
96 * In addition to writing out user data, we must also execute synctasks during
97 * the syncing context. A synctask is the mechanism by which some
98 * administrative activities work such as creating and destroying snapshots or
99 * datasets. Note that when a synctask is initiated it enters the open txg,
100 * and ZFS then pushes that txg as quickly as possible to completion of the
101 * syncing state in order to reduce the latency of the administrative
102 * activity. To complete the syncing state, ZFS writes out a new uberblock,
103 * the root of the tree of blocks that comprise all state stored on the ZFS
104 * pool. Finally, if there is a quiesced txg waiting, we signal that it can
105 * now transition to the syncing state.
106 */
107
108 static void txg_sync_thread(dsl_pool_t *dp);
109 static void txg_quiesce_thread(dsl_pool_t *dp);
110
111 int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */
112
113 /*
114 * Prepare the txg subsystem.
115 */
116 void
117 txg_init(dsl_pool_t *dp, uint64_t txg)
118 {
119 tx_state_t *tx = &dp->dp_tx;
120 int c;
121 bzero(tx, sizeof (tx_state_t));
122
123 tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
124
125 for (c = 0; c < max_ncpus; c++) {
126 int i;
127
128 mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
129 for (i = 0; i < TXG_SIZE; i++) {
130 cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
131 NULL);
132 list_create(&tx->tx_cpu[c].tc_callbacks[i],
133 sizeof (dmu_tx_callback_t),
134 offsetof(dmu_tx_callback_t, dcb_node));
135 }
136 }
137
138 mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);
139
140 cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
141 cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
142 cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
143 cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
144 cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);
145
146 tx->tx_open_txg = txg;
147 }
148
149 /*
150 * Close down the txg subsystem.
151 */
152 void
153 txg_fini(dsl_pool_t *dp)
154 {
155 tx_state_t *tx = &dp->dp_tx;
156 int c;
157
158 ASSERT(tx->tx_threads == 0);
159
160 mutex_destroy(&tx->tx_sync_lock);
161
162 cv_destroy(&tx->tx_sync_more_cv);
163 cv_destroy(&tx->tx_sync_done_cv);
164 cv_destroy(&tx->tx_quiesce_more_cv);
165 cv_destroy(&tx->tx_quiesce_done_cv);
166 cv_destroy(&tx->tx_exit_cv);
167
168 for (c = 0; c < max_ncpus; c++) {
169 int i;
170
171 mutex_destroy(&tx->tx_cpu[c].tc_lock);
172 for (i = 0; i < TXG_SIZE; i++) {
173 cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
174 list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
175 }
176 }
177
178 if (tx->tx_commit_cb_taskq != NULL)
179 taskq_destroy(tx->tx_commit_cb_taskq);
180
181 kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
182
183 bzero(tx, sizeof (tx_state_t));
184 }
185
186 /*
187 * Start syncing transaction groups.
188 */
189 void
190 txg_sync_start(dsl_pool_t *dp)
191 {
192 tx_state_t *tx = &dp->dp_tx;
193
194 mutex_enter(&tx->tx_sync_lock);
195
196 dprintf("pool %p\n", dp);
197
198 ASSERT(tx->tx_threads == 0);
199
200 tx->tx_threads = 2;
201
202 tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
203 dp, 0, &p0, TS_RUN, minclsyspri);
204
205 /*
206 * The sync thread can need a larger-than-default stack size on
207 * 32-bit x86. This is due in part to nested pools and
208 * scrub_visitbp() recursion.
209 */
210 tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread,
211 dp, 0, &p0, TS_RUN, minclsyspri);
212
213 mutex_exit(&tx->tx_sync_lock);
214 }
215
216 static void
217 txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr)
218 {
219 CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
220 mutex_enter(&tx->tx_sync_lock);
221 }
222
223 static void
224 txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp)
225 {
226 ASSERT(*tpp != NULL);
227 *tpp = NULL;
228 tx->tx_threads--;
229 cv_broadcast(&tx->tx_exit_cv);
230 CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */
231 thread_exit();
232 }
233
234 static void
235 txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time)
236 {
237 CALLB_CPR_SAFE_BEGIN(cpr);
238
239 if (time)
240 (void) cv_timedwait(cv, &tx->tx_sync_lock,
241 ddi_get_lbolt() + time);
242 else
243 cv_wait(cv, &tx->tx_sync_lock);
244
245 CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
246 }
247
248 /*
249 * Stop syncing transaction groups.
250 */
251 void
252 txg_sync_stop(dsl_pool_t *dp)
253 {
254 tx_state_t *tx = &dp->dp_tx;
255
256 dprintf("pool %p\n", dp);
257 /*
258 * Finish off any work in progress.
259 */
260 ASSERT(tx->tx_threads == 2);
261
262 /*
263 * We need to ensure that we've vacated the deferred space_maps.
264 */
265 txg_wait_synced(dp, tx->tx_open_txg + TXG_DEFER_SIZE);
266
267 /*
268 * Wake all sync threads and wait for them to die.
269 */
270 mutex_enter(&tx->tx_sync_lock);
271
272 ASSERT(tx->tx_threads == 2);
273
274 tx->tx_exiting = 1;
275
276 cv_broadcast(&tx->tx_quiesce_more_cv);
277 cv_broadcast(&tx->tx_quiesce_done_cv);
278 cv_broadcast(&tx->tx_sync_more_cv);
279
280 while (tx->tx_threads != 0)
281 cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);
282
283 tx->tx_exiting = 0;
284
285 mutex_exit(&tx->tx_sync_lock);
286 }
287
288 uint64_t
289 txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
290 {
291 tx_state_t *tx = &dp->dp_tx;
292 tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
293 uint64_t txg;
294
295 mutex_enter(&tc->tc_lock);
296
297 txg = tx->tx_open_txg;
298 tc->tc_count[txg & TXG_MASK]++;
299
300 th->th_cpu = tc;
301 th->th_txg = txg;
302
303 return (txg);
304 }
305
306 void
307 txg_rele_to_quiesce(txg_handle_t *th)
308 {
309 tx_cpu_t *tc = th->th_cpu;
310
311 mutex_exit(&tc->tc_lock);
312 }
313
314 void
315 txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
316 {
317 tx_cpu_t *tc = th->th_cpu;
318 int g = th->th_txg & TXG_MASK;
319
320 mutex_enter(&tc->tc_lock);
321 list_move_tail(&tc->tc_callbacks[g], tx_callbacks);
322 mutex_exit(&tc->tc_lock);
323 }
324
325 void
326 txg_rele_to_sync(txg_handle_t *th)
327 {
328 tx_cpu_t *tc = th->th_cpu;
329 int g = th->th_txg & TXG_MASK;
330
331 mutex_enter(&tc->tc_lock);
332 ASSERT(tc->tc_count[g] != 0);
333 if (--tc->tc_count[g] == 0)
334 cv_broadcast(&tc->tc_cv[g]);
335 mutex_exit(&tc->tc_lock);
336
337 th->th_cpu = NULL; /* defensive */
338 }
339
340 /*
341 * Quiesce, v.: to render temporarily inactive or disabled
342 *
343 * Blocks until all transactions in the group are committed.
344 *
345 * On return, the transaction group has reached a stable state in which it can
346 * then be passed off to the syncing context.
347 */
348 static void
349 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
350 {
351 tx_state_t *tx = &dp->dp_tx;
352 int g = txg & TXG_MASK;
353 int c;
354
355 /*
356 * Grab all tx_cpu locks so nobody else can get into this txg.
357 */
358 for (c = 0; c < max_ncpus; c++)
359 mutex_enter(&tx->tx_cpu[c].tc_lock);
360
361 ASSERT(txg == tx->tx_open_txg);
362 tx->tx_open_txg++;
363
364 DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg);
365 DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg);
366
367 /*
368 * Now that we've incremented tx_open_txg, we can let threads
369 * enter the next transaction group.
370 */
371 for (c = 0; c < max_ncpus; c++)
372 mutex_exit(&tx->tx_cpu[c].tc_lock);
373
374 /*
375 * Quiesce the transaction group by waiting for everyone to txg_exit().
376 */
377 for (c = 0; c < max_ncpus; c++) {
378 tx_cpu_t *tc = &tx->tx_cpu[c];
379 mutex_enter(&tc->tc_lock);
380 while (tc->tc_count[g] != 0)
381 cv_wait(&tc->tc_cv[g], &tc->tc_lock);
382 mutex_exit(&tc->tc_lock);
383 }
384 }
385
386 static void
387 txg_do_callbacks(list_t *cb_list)
388 {
389 dmu_tx_do_callbacks(cb_list, 0);
390
391 list_destroy(cb_list);
392
393 kmem_free(cb_list, sizeof (list_t));
394 }
395
396 /*
397 * Dispatch the commit callbacks registered on this txg to worker threads.
398 *
399 * If no callbacks are registered for a given TXG, nothing happens.
400 * This function creates a taskq for the associated pool, if needed.
401 */
402 static void
403 txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
404 {
405 int c;
406 tx_state_t *tx = &dp->dp_tx;
407 list_t *cb_list;
408
409 for (c = 0; c < max_ncpus; c++) {
410 tx_cpu_t *tc = &tx->tx_cpu[c];
411 /*
412 * No need to lock tx_cpu_t at this point, since this can
413 * only be called once a txg has been synced.
414 */
415
416 int g = txg & TXG_MASK;
417
418 if (list_is_empty(&tc->tc_callbacks[g]))
419 continue;
420
421 if (tx->tx_commit_cb_taskq == NULL) {
422 /*
423 * Commit callback taskq hasn't been created yet.
424 */
425 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
426 max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
427 TASKQ_PREPOPULATE);
428 }
429
430 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
431 list_create(cb_list, sizeof (dmu_tx_callback_t),
432 offsetof(dmu_tx_callback_t, dcb_node));
433
434 list_move_tail(&tc->tc_callbacks[g], cb_list);
435
436 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
437 txg_do_callbacks, cb_list, TQ_SLEEP);
438 }
439 }
440
441 static void
442 txg_sync_thread(dsl_pool_t *dp)
443 {
444 spa_t *spa = dp->dp_spa;
445 tx_state_t *tx = &dp->dp_tx;
446 callb_cpr_t cpr;
447 uint64_t start, delta;
448
449 txg_thread_enter(tx, &cpr);
450
451 start = delta = 0;
452 for (;;) {
453 uint64_t timer, timeout = zfs_txg_timeout * hz;
454 uint64_t txg;
455
456 /*
457 * We sync when we're scanning, there's someone waiting
458 * on us, or the quiesce thread has handed off a txg to
459 * us, or we have reached our timeout.
460 */
461 timer = (delta >= timeout ? 0 : timeout - delta);
462 while (!dsl_scan_active(dp->dp_scan) &&
463 !tx->tx_exiting && timer > 0 &&
464 tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
465 tx->tx_quiesced_txg == 0) {
466 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
467 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
468 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
469 delta = ddi_get_lbolt() - start;
470 timer = (delta > timeout ? 0 : timeout - delta);
471 }
472
473 /*
474 * Wait until the quiesce thread hands off a txg to us,
475 * prompting it to do so if necessary.
476 */
477 while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) {
478 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
479 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
480 cv_broadcast(&tx->tx_quiesce_more_cv);
481 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
482 }
483
484 if (tx->tx_exiting)
485 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
486
487 /*
488 * Consume the quiesced txg which has been handed off to
489 * us. This may cause the quiescing thread to now be
490 * able to quiesce another txg, so we must signal it.
491 */
492 txg = tx->tx_quiesced_txg;
493 tx->tx_quiesced_txg = 0;
494 tx->tx_syncing_txg = txg;
495 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
496 cv_broadcast(&tx->tx_quiesce_more_cv);
497
498 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
499 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
500 mutex_exit(&tx->tx_sync_lock);
501
502 start = ddi_get_lbolt();
503 spa_sync(spa, txg);
504 delta = ddi_get_lbolt() - start;
505
506 mutex_enter(&tx->tx_sync_lock);
507 tx->tx_synced_txg = txg;
508 tx->tx_syncing_txg = 0;
509 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
510 cv_broadcast(&tx->tx_sync_done_cv);
511
512 /*
513 * Dispatch commit callbacks to worker threads.
514 */
515 txg_dispatch_callbacks(dp, txg);
516 }
517 }
518
519 static void
520 txg_quiesce_thread(dsl_pool_t *dp)
521 {
522 tx_state_t *tx = &dp->dp_tx;
523 callb_cpr_t cpr;
524
525 txg_thread_enter(tx, &cpr);
526
527 for (;;) {
528 uint64_t txg;
529
530 /*
531 * We quiesce when there's someone waiting on us.
532 * However, we can only have one txg in "quiescing" or
533 * "quiesced, waiting to sync" state. So we wait until
534 * the "quiesced, waiting to sync" txg has been consumed
535 * by the sync thread.
536 */
537 while (!tx->tx_exiting &&
538 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
539 tx->tx_quiesced_txg != 0))
540 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
541
542 if (tx->tx_exiting)
543 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
544
545 txg = tx->tx_open_txg;
546 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
547 txg, tx->tx_quiesce_txg_waiting,
548 tx->tx_sync_txg_waiting);
549 mutex_exit(&tx->tx_sync_lock);
550 txg_quiesce(dp, txg);
551 mutex_enter(&tx->tx_sync_lock);
552
553 /*
554 * Hand this txg off to the sync thread.
555 */
556 dprintf("quiesce done, handing off txg %llu\n", txg);
557 tx->tx_quiesced_txg = txg;
558 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
559 cv_broadcast(&tx->tx_sync_more_cv);
560 cv_broadcast(&tx->tx_quiesce_done_cv);
561 }
562 }
563
564 /*
565 * Delay this thread by delay nanoseconds if we are still in the open
566 * transaction group and there is already a waiting txg quiesing or quiesced.
567 * Abort the delay if this txg stalls or enters the quiesing state.
568 */
569 void
570 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
571 {
572 tx_state_t *tx = &dp->dp_tx;
573 hrtime_t start = gethrtime();
574
575 /* don't delay if this txg could transition to quiesing immediately */
576 if (tx->tx_open_txg > txg ||
577 tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
578 return;
579
580 mutex_enter(&tx->tx_sync_lock);
581 if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
582 mutex_exit(&tx->tx_sync_lock);
583 return;
584 }
585
586 while (gethrtime() - start < delay &&
587 tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) {
588 (void) cv_timedwait_hires(&tx->tx_quiesce_more_cv,
589 &tx->tx_sync_lock, delay, resolution, 0);
590 }
591
592 mutex_exit(&tx->tx_sync_lock);
593 }
594
595 void
596 txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
597 {
598 tx_state_t *tx = &dp->dp_tx;
599
600 ASSERT(!dsl_pool_config_held(dp));
601
602 mutex_enter(&tx->tx_sync_lock);
603 ASSERT(tx->tx_threads == 2);
604 if (txg == 0)
605 txg = tx->tx_open_txg + TXG_DEFER_SIZE;
606 if (tx->tx_sync_txg_waiting < txg)
607 tx->tx_sync_txg_waiting = txg;
608 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
609 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
610 while (tx->tx_synced_txg < txg) {
611 dprintf("broadcasting sync more "
612 "tx_synced=%llu waiting=%llu dp=%p\n",
613 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
614 cv_broadcast(&tx->tx_sync_more_cv);
615 cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
616 }
617 mutex_exit(&tx->tx_sync_lock);
618 }
619
620 void
621 txg_wait_open(dsl_pool_t *dp, uint64_t txg)
622 {
623 tx_state_t *tx = &dp->dp_tx;
624
625 ASSERT(!dsl_pool_config_held(dp));
626
627 mutex_enter(&tx->tx_sync_lock);
628 ASSERT(tx->tx_threads == 2);
629 if (txg == 0)
630 txg = tx->tx_open_txg + 1;
631 if (tx->tx_quiesce_txg_waiting < txg)
632 tx->tx_quiesce_txg_waiting = txg;
633 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
634 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
635 while (tx->tx_open_txg < txg) {
636 cv_broadcast(&tx->tx_quiesce_more_cv);
637 cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
638 }
639 mutex_exit(&tx->tx_sync_lock);
640 }
641
642 boolean_t
643 txg_stalled(dsl_pool_t *dp)
644 {
645 tx_state_t *tx = &dp->dp_tx;
646 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
647 }
648
649 boolean_t
650 txg_sync_waiting(dsl_pool_t *dp)
651 {
652 tx_state_t *tx = &dp->dp_tx;
653
654 return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
655 tx->tx_quiesced_txg != 0);
656 }
657
658 /*
659 * Per-txg object lists.
660 */
661 void
662 txg_list_create(txg_list_t *tl, size_t offset)
663 {
664 int t;
665
666 mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
667
668 tl->tl_offset = offset;
669
670 for (t = 0; t < TXG_SIZE; t++)
671 tl->tl_head[t] = NULL;
672 }
673
674 void
675 txg_list_destroy(txg_list_t *tl)
676 {
677 int t;
678
679 for (t = 0; t < TXG_SIZE; t++)
680 ASSERT(txg_list_empty(tl, t));
681
682 mutex_destroy(&tl->tl_lock);
683 }
684
685 boolean_t
686 txg_list_empty(txg_list_t *tl, uint64_t txg)
687 {
688 return (tl->tl_head[txg & TXG_MASK] == NULL);
689 }
690
691 /*
692 * Add an entry to the list (unless it's already on the list).
693 * Returns B_TRUE if it was actually added.
694 */
695 boolean_t
696 txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
697 {
698 int t = txg & TXG_MASK;
699 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
700 boolean_t add;
701
702 mutex_enter(&tl->tl_lock);
703 add = (tn->tn_member[t] == 0);
704 if (add) {
705 tn->tn_member[t] = 1;
706 tn->tn_next[t] = tl->tl_head[t];
707 tl->tl_head[t] = tn;
708 }
709 mutex_exit(&tl->tl_lock);
710
711 return (add);
712 }
713
714 /*
715 * Add an entry to the end of the list, unless it's already on the list.
716 * (walks list to find end)
717 * Returns B_TRUE if it was actually added.
718 */
719 boolean_t
720 txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg)
721 {
722 int t = txg & TXG_MASK;
723 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
724 boolean_t add;
725
726 mutex_enter(&tl->tl_lock);
727 add = (tn->tn_member[t] == 0);
728 if (add) {
729 txg_node_t **tp;
730
731 for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t])
732 continue;
733
734 tn->tn_member[t] = 1;
735 tn->tn_next[t] = NULL;
736 *tp = tn;
737 }
738 mutex_exit(&tl->tl_lock);
739
740 return (add);
741 }
742
743 /*
744 * Remove the head of the list and return it.
745 */
746 void *
747 txg_list_remove(txg_list_t *tl, uint64_t txg)
748 {
749 int t = txg & TXG_MASK;
750 txg_node_t *tn;
751 void *p = NULL;
752
753 mutex_enter(&tl->tl_lock);
754 if ((tn = tl->tl_head[t]) != NULL) {
755 p = (char *)tn - tl->tl_offset;
756 tl->tl_head[t] = tn->tn_next[t];
757 tn->tn_next[t] = NULL;
758 tn->tn_member[t] = 0;
759 }
760 mutex_exit(&tl->tl_lock);
761
762 return (p);
763 }
764
765 /*
766 * Remove a specific item from the list and return it.
767 */
768 void *
769 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
770 {
771 int t = txg & TXG_MASK;
772 txg_node_t *tn, **tp;
773
774 mutex_enter(&tl->tl_lock);
775
776 for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
777 if ((char *)tn - tl->tl_offset == p) {
778 *tp = tn->tn_next[t];
779 tn->tn_next[t] = NULL;
780 tn->tn_member[t] = 0;
781 mutex_exit(&tl->tl_lock);
782 return (p);
783 }
784 }
785
786 mutex_exit(&tl->tl_lock);
787
788 return (NULL);
789 }
790
791 boolean_t
792 txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
793 {
794 int t = txg & TXG_MASK;
795 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
796
797 return (tn->tn_member[t] != 0);
798 }
799
800 /*
801 * Walk a txg list -- only safe if you know it's not changing.
802 */
803 void *
804 txg_list_head(txg_list_t *tl, uint64_t txg)
805 {
806 int t = txg & TXG_MASK;
807 txg_node_t *tn = tl->tl_head[t];
808
809 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
810 }
811
812 void *
813 txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
814 {
815 int t = txg & TXG_MASK;
816 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
817
818 tn = tn->tn_next[t];
819
820 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
821 }