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 static void
341 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
342 {
343 tx_state_t *tx = &dp->dp_tx;
344 int g = txg & TXG_MASK;
345 int c;
346
347 /*
348 * Grab all tx_cpu locks so nobody else can get into this txg.
349 */
350 for (c = 0; c < max_ncpus; c++)
351 mutex_enter(&tx->tx_cpu[c].tc_lock);
352
353 ASSERT(txg == tx->tx_open_txg);
354 tx->tx_open_txg++;
355
356 DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg);
357 DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg);
358
359 /*
360 * Now that we've incremented tx_open_txg, we can let threads
361 * enter the next transaction group.
362 */
363 for (c = 0; c < max_ncpus; c++)
364 mutex_exit(&tx->tx_cpu[c].tc_lock);
365
366 /*
367 * Quiesce the transaction group by waiting for everyone to txg_exit().
368 */
369 for (c = 0; c < max_ncpus; c++) {
370 tx_cpu_t *tc = &tx->tx_cpu[c];
371 mutex_enter(&tc->tc_lock);
372 while (tc->tc_count[g] != 0)
373 cv_wait(&tc->tc_cv[g], &tc->tc_lock);
374 mutex_exit(&tc->tc_lock);
375 }
376 }
377
378 static void
379 txg_do_callbacks(list_t *cb_list)
380 {
381 dmu_tx_do_callbacks(cb_list, 0);
382
383 list_destroy(cb_list);
384
385 kmem_free(cb_list, sizeof (list_t));
386 }
387
388 /*
389 * Dispatch the commit callbacks registered on this txg to worker threads.
390 */
391 static void
392 txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
393 {
394 int c;
395 tx_state_t *tx = &dp->dp_tx;
396 list_t *cb_list;
397
398 for (c = 0; c < max_ncpus; c++) {
399 tx_cpu_t *tc = &tx->tx_cpu[c];
400 /* No need to lock tx_cpu_t at this point */
401
402 int g = txg & TXG_MASK;
403
404 if (list_is_empty(&tc->tc_callbacks[g]))
405 continue;
406
407 if (tx->tx_commit_cb_taskq == NULL) {
408 /*
409 * Commit callback taskq hasn't been created yet.
410 */
411 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
412 max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
413 TASKQ_PREPOPULATE);
414 }
415
416 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
417 list_create(cb_list, sizeof (dmu_tx_callback_t),
418 offsetof(dmu_tx_callback_t, dcb_node));
419
420 list_move_tail(cb_list, &tc->tc_callbacks[g]);
421
422 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
423 txg_do_callbacks, cb_list, TQ_SLEEP);
424 }
425 }
426
427 static void
428 txg_sync_thread(dsl_pool_t *dp)
429 {
430 spa_t *spa = dp->dp_spa;
431 tx_state_t *tx = &dp->dp_tx;
432 callb_cpr_t cpr;
433 uint64_t start, delta;
434
435 txg_thread_enter(tx, &cpr);
436
437 start = delta = 0;
438 for (;;) {
439 uint64_t timer, timeout = zfs_txg_timeout * hz;
440 uint64_t txg;
441
442 /*
443 * We sync when we're scanning, there's someone waiting
444 * on us, or the quiesce thread has handed off a txg to
445 * us, or we have reached our timeout.
446 */
447 timer = (delta >= timeout ? 0 : timeout - delta);
448 while (!dsl_scan_active(dp->dp_scan) &&
449 !tx->tx_exiting && timer > 0 &&
450 tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
451 tx->tx_quiesced_txg == 0) {
452 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
453 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
454 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
455 delta = ddi_get_lbolt() - start;
456 timer = (delta > timeout ? 0 : timeout - delta);
457 }
458
459 /*
460 * Wait until the quiesce thread hands off a txg to us,
461 * prompting it to do so if necessary.
462 */
463 while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) {
464 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
465 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
466 cv_broadcast(&tx->tx_quiesce_more_cv);
467 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
468 }
469
470 if (tx->tx_exiting)
471 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
472
473 /*
474 * Consume the quiesced txg which has been handed off to
475 * us. This may cause the quiescing thread to now be
476 * able to quiesce another txg, so we must signal it.
477 */
478 txg = tx->tx_quiesced_txg;
479 tx->tx_quiesced_txg = 0;
480 tx->tx_syncing_txg = txg;
481 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
482 cv_broadcast(&tx->tx_quiesce_more_cv);
483
484 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
485 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
486 mutex_exit(&tx->tx_sync_lock);
487
488 start = ddi_get_lbolt();
489 spa_sync(spa, txg);
490 delta = ddi_get_lbolt() - start;
491
492 mutex_enter(&tx->tx_sync_lock);
493 tx->tx_synced_txg = txg;
494 tx->tx_syncing_txg = 0;
495 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
496 cv_broadcast(&tx->tx_sync_done_cv);
497
498 /*
499 * Dispatch commit callbacks to worker threads.
500 */
501 txg_dispatch_callbacks(dp, txg);
502 }
503 }
504
505 static void
506 txg_quiesce_thread(dsl_pool_t *dp)
507 {
508 tx_state_t *tx = &dp->dp_tx;
509 callb_cpr_t cpr;
510
511 txg_thread_enter(tx, &cpr);
512
513 for (;;) {
514 uint64_t txg;
515
516 /*
517 * We quiesce when there's someone waiting on us.
518 * However, we can only have one txg in "quiescing" or
519 * "quiesced, waiting to sync" state. So we wait until
520 * the "quiesced, waiting to sync" txg has been consumed
521 * by the sync thread.
522 */
523 while (!tx->tx_exiting &&
524 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
525 tx->tx_quiesced_txg != 0))
526 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
527
528 if (tx->tx_exiting)
529 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
530
531 txg = tx->tx_open_txg;
532 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
533 txg, tx->tx_quiesce_txg_waiting,
534 tx->tx_sync_txg_waiting);
535 mutex_exit(&tx->tx_sync_lock);
536 txg_quiesce(dp, txg);
537 mutex_enter(&tx->tx_sync_lock);
538
539 /*
540 * Hand this txg off to the sync thread.
541 */
542 dprintf("quiesce done, handing off txg %llu\n", txg);
543 tx->tx_quiesced_txg = txg;
544 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
545 cv_broadcast(&tx->tx_sync_more_cv);
546 cv_broadcast(&tx->tx_quiesce_done_cv);
547 }
548 }
549
550 /*
551 * Delay this thread by delay nanoseconds if we are still in the open
552 * transaction group and there is already a waiting txg quiesing or quiesced.
553 * Abort the delay if this txg stalls or enters the quiesing state.
554 */
555 void
556 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
557 {
558 tx_state_t *tx = &dp->dp_tx;
559 hrtime_t start = gethrtime();
560
561 /* don't delay if this txg could transition to quiesing immediately */
562 if (tx->tx_open_txg > txg ||
563 tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
564 return;
565
566 mutex_enter(&tx->tx_sync_lock);
567 if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
568 mutex_exit(&tx->tx_sync_lock);
569 return;
570 }
571
572 while (gethrtime() - start < delay &&
573 tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) {
574 (void) cv_timedwait_hires(&tx->tx_quiesce_more_cv,
575 &tx->tx_sync_lock, delay, resolution, 0);
576 }
577
578 mutex_exit(&tx->tx_sync_lock);
579 }
580
581 void
582 txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
583 {
584 tx_state_t *tx = &dp->dp_tx;
585
586 ASSERT(!dsl_pool_config_held(dp));
587
588 mutex_enter(&tx->tx_sync_lock);
589 ASSERT(tx->tx_threads == 2);
590 if (txg == 0)
591 txg = tx->tx_open_txg + TXG_DEFER_SIZE;
592 if (tx->tx_sync_txg_waiting < txg)
593 tx->tx_sync_txg_waiting = txg;
594 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
595 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
596 while (tx->tx_synced_txg < txg) {
597 dprintf("broadcasting sync more "
598 "tx_synced=%llu waiting=%llu dp=%p\n",
599 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
600 cv_broadcast(&tx->tx_sync_more_cv);
601 cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
602 }
603 mutex_exit(&tx->tx_sync_lock);
604 }
605
606 void
607 txg_wait_open(dsl_pool_t *dp, uint64_t txg)
608 {
609 tx_state_t *tx = &dp->dp_tx;
610
611 ASSERT(!dsl_pool_config_held(dp));
612
613 mutex_enter(&tx->tx_sync_lock);
614 ASSERT(tx->tx_threads == 2);
615 if (txg == 0)
616 txg = tx->tx_open_txg + 1;
617 if (tx->tx_quiesce_txg_waiting < txg)
618 tx->tx_quiesce_txg_waiting = txg;
619 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
620 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
621 while (tx->tx_open_txg < txg) {
622 cv_broadcast(&tx->tx_quiesce_more_cv);
623 cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
624 }
625 mutex_exit(&tx->tx_sync_lock);
626 }
627
628 boolean_t
629 txg_stalled(dsl_pool_t *dp)
630 {
631 tx_state_t *tx = &dp->dp_tx;
632 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
633 }
634
635 boolean_t
636 txg_sync_waiting(dsl_pool_t *dp)
637 {
638 tx_state_t *tx = &dp->dp_tx;
639
640 return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
641 tx->tx_quiesced_txg != 0);
642 }
643
644 /*
645 * Per-txg object lists.
646 */
647 void
648 txg_list_create(txg_list_t *tl, size_t offset)
649 {
650 int t;
651
652 mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
653
654 tl->tl_offset = offset;
655
656 for (t = 0; t < TXG_SIZE; t++)
657 tl->tl_head[t] = NULL;
658 }
659
660 void
661 txg_list_destroy(txg_list_t *tl)
662 {
663 int t;
664
665 for (t = 0; t < TXG_SIZE; t++)
666 ASSERT(txg_list_empty(tl, t));
667
668 mutex_destroy(&tl->tl_lock);
669 }
670
671 boolean_t
672 txg_list_empty(txg_list_t *tl, uint64_t txg)
673 {
674 return (tl->tl_head[txg & TXG_MASK] == NULL);
675 }
676
677 /*
678 * Add an entry to the list (unless it's already on the list).
679 * Returns B_TRUE if it was actually added.
680 */
681 boolean_t
682 txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
683 {
684 int t = txg & TXG_MASK;
685 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
686 boolean_t add;
687
688 mutex_enter(&tl->tl_lock);
689 add = (tn->tn_member[t] == 0);
690 if (add) {
691 tn->tn_member[t] = 1;
692 tn->tn_next[t] = tl->tl_head[t];
693 tl->tl_head[t] = tn;
694 }
695 mutex_exit(&tl->tl_lock);
696
697 return (add);
698 }
699
700 /*
701 * Add an entry to the end of the list, unless it's already on the list.
702 * (walks list to find end)
703 * Returns B_TRUE if it was actually added.
704 */
705 boolean_t
706 txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg)
707 {
708 int t = txg & TXG_MASK;
709 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
710 boolean_t add;
711
712 mutex_enter(&tl->tl_lock);
713 add = (tn->tn_member[t] == 0);
714 if (add) {
715 txg_node_t **tp;
716
717 for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t])
718 continue;
719
720 tn->tn_member[t] = 1;
721 tn->tn_next[t] = NULL;
722 *tp = tn;
723 }
724 mutex_exit(&tl->tl_lock);
725
726 return (add);
727 }
728
729 /*
730 * Remove the head of the list and return it.
731 */
732 void *
733 txg_list_remove(txg_list_t *tl, uint64_t txg)
734 {
735 int t = txg & TXG_MASK;
736 txg_node_t *tn;
737 void *p = NULL;
738
739 mutex_enter(&tl->tl_lock);
740 if ((tn = tl->tl_head[t]) != NULL) {
741 p = (char *)tn - tl->tl_offset;
742 tl->tl_head[t] = tn->tn_next[t];
743 tn->tn_next[t] = NULL;
744 tn->tn_member[t] = 0;
745 }
746 mutex_exit(&tl->tl_lock);
747
748 return (p);
749 }
750
751 /*
752 * Remove a specific item from the list and return it.
753 */
754 void *
755 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
756 {
757 int t = txg & TXG_MASK;
758 txg_node_t *tn, **tp;
759
760 mutex_enter(&tl->tl_lock);
761
762 for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
763 if ((char *)tn - tl->tl_offset == p) {
764 *tp = tn->tn_next[t];
765 tn->tn_next[t] = NULL;
766 tn->tn_member[t] = 0;
767 mutex_exit(&tl->tl_lock);
768 return (p);
769 }
770 }
771
772 mutex_exit(&tl->tl_lock);
773
774 return (NULL);
775 }
776
777 boolean_t
778 txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
779 {
780 int t = txg & TXG_MASK;
781 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
782
783 return (tn->tn_member[t] != 0);
784 }
785
786 /*
787 * Walk a txg list -- only safe if you know it's not changing.
788 */
789 void *
790 txg_list_head(txg_list_t *tl, uint64_t txg)
791 {
792 int t = txg & TXG_MASK;
793 txg_node_t *tn = tl->tl_head[t];
794
795 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
796 }
797
798 void *
799 txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
800 {
801 int t = txg & TXG_MASK;
802 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
803
804 tn = tn->tn_next[t];
805
806 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
807 }