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 mutex_init(&tx->tx_cpu[c].tc_open_lock, NULL, MUTEX_DEFAULT,
130 NULL);
131 for (i = 0; i < TXG_SIZE; i++) {
132 cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
133 NULL);
134 list_create(&tx->tx_cpu[c].tc_callbacks[i],
135 sizeof (dmu_tx_callback_t),
136 offsetof(dmu_tx_callback_t, dcb_node));
137 }
138 }
139
140 mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);
141
142 cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
143 cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
144 cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
145 cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
146 cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);
147
148 tx->tx_open_txg = txg;
149 }
150
151 /*
152 * Close down the txg subsystem.
153 */
154 void
155 txg_fini(dsl_pool_t *dp)
156 {
157 tx_state_t *tx = &dp->dp_tx;
158 int c;
159
160 ASSERT(tx->tx_threads == 0);
161
162 mutex_destroy(&tx->tx_sync_lock);
163
164 cv_destroy(&tx->tx_sync_more_cv);
165 cv_destroy(&tx->tx_sync_done_cv);
166 cv_destroy(&tx->tx_quiesce_more_cv);
167 cv_destroy(&tx->tx_quiesce_done_cv);
168 cv_destroy(&tx->tx_exit_cv);
169
170 for (c = 0; c < max_ncpus; c++) {
171 int i;
172
173 mutex_destroy(&tx->tx_cpu[c].tc_open_lock);
174 mutex_destroy(&tx->tx_cpu[c].tc_lock);
175 for (i = 0; i < TXG_SIZE; i++) {
176 cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
177 list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
178 }
179 }
180
181 if (tx->tx_commit_cb_taskq != NULL)
182 taskq_destroy(tx->tx_commit_cb_taskq);
183
184 kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
185
186 bzero(tx, sizeof (tx_state_t));
187 }
188
189 /*
190 * Start syncing transaction groups.
191 */
192 void
193 txg_sync_start(dsl_pool_t *dp)
194 {
195 tx_state_t *tx = &dp->dp_tx;
196
197 mutex_enter(&tx->tx_sync_lock);
198
199 dprintf("pool %p\n", dp);
200
201 ASSERT(tx->tx_threads == 0);
202
203 tx->tx_threads = 2;
204
205 tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
206 dp, 0, &p0, TS_RUN, minclsyspri);
207
208 /*
209 * The sync thread can need a larger-than-default stack size on
210 * 32-bit x86. This is due in part to nested pools and
211 * scrub_visitbp() recursion.
212 */
213 tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread,
214 dp, 0, &p0, TS_RUN, minclsyspri);
215
216 mutex_exit(&tx->tx_sync_lock);
217 }
218
219 static void
220 txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr)
221 {
222 CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
223 mutex_enter(&tx->tx_sync_lock);
224 }
225
226 static void
227 txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp)
228 {
229 ASSERT(*tpp != NULL);
230 *tpp = NULL;
231 tx->tx_threads--;
232 cv_broadcast(&tx->tx_exit_cv);
233 CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */
234 thread_exit();
235 }
236
237 static void
238 txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time)
239 {
240 CALLB_CPR_SAFE_BEGIN(cpr);
241
242 if (time)
243 (void) cv_timedwait(cv, &tx->tx_sync_lock,
244 ddi_get_lbolt() + time);
245 else
246 cv_wait(cv, &tx->tx_sync_lock);
247
248 CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
249 }
250
251 /*
252 * Stop syncing transaction groups.
253 */
254 void
255 txg_sync_stop(dsl_pool_t *dp)
256 {
257 tx_state_t *tx = &dp->dp_tx;
258
259 dprintf("pool %p\n", dp);
260 /*
261 * Finish off any work in progress.
262 */
263 ASSERT(tx->tx_threads == 2);
264
265 /*
266 * We need to ensure that we've vacated the deferred space_maps.
267 */
268 txg_wait_synced(dp, tx->tx_open_txg + TXG_DEFER_SIZE);
269
270 /*
271 * Wake all sync threads and wait for them to die.
272 */
273 mutex_enter(&tx->tx_sync_lock);
274
275 ASSERT(tx->tx_threads == 2);
276
277 tx->tx_exiting = 1;
278
279 cv_broadcast(&tx->tx_quiesce_more_cv);
280 cv_broadcast(&tx->tx_quiesce_done_cv);
281 cv_broadcast(&tx->tx_sync_more_cv);
282
283 while (tx->tx_threads != 0)
284 cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);
285
286 tx->tx_exiting = 0;
287
288 mutex_exit(&tx->tx_sync_lock);
289 }
290
291 uint64_t
292 txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
293 {
294 tx_state_t *tx = &dp->dp_tx;
295 tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
296 uint64_t txg;
297
298 mutex_enter(&tc->tc_open_lock);
299 txg = tx->tx_open_txg;
300
301 mutex_enter(&tc->tc_lock);
302 tc->tc_count[txg & TXG_MASK]++;
303 mutex_exit(&tc->tc_lock);
304
305 th->th_cpu = tc;
306 th->th_txg = txg;
307
308 return (txg);
309 }
310
311 void
312 txg_rele_to_quiesce(txg_handle_t *th)
313 {
314 tx_cpu_t *tc = th->th_cpu;
315
316 ASSERT(!MUTEX_HELD(&tc->tc_lock));
317 mutex_exit(&tc->tc_open_lock);
318 }
319
320 void
321 txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
322 {
323 tx_cpu_t *tc = th->th_cpu;
324 int g = th->th_txg & TXG_MASK;
325
326 mutex_enter(&tc->tc_lock);
327 list_move_tail(&tc->tc_callbacks[g], tx_callbacks);
328 mutex_exit(&tc->tc_lock);
329 }
330
331 void
332 txg_rele_to_sync(txg_handle_t *th)
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 ASSERT(tc->tc_count[g] != 0);
339 if (--tc->tc_count[g] == 0)
340 cv_broadcast(&tc->tc_cv[g]);
341 mutex_exit(&tc->tc_lock);
342
343 th->th_cpu = NULL; /* defensive */
344 }
345
346 /*
347 * Blocks until all transactions in the group are committed.
348 *
349 * On return, the transaction group has reached a stable state in which it can
350 * then be passed off to the syncing context.
351 */
352 static void
353 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
354 {
355 tx_state_t *tx = &dp->dp_tx;
356 int g = txg & TXG_MASK;
357 int c;
358
359 /*
360 * Grab all tc_open_locks so nobody else can get into this txg.
361 */
362 for (c = 0; c < max_ncpus; c++)
363 mutex_enter(&tx->tx_cpu[c].tc_open_lock);
364
365 ASSERT(txg == tx->tx_open_txg);
366 tx->tx_open_txg++;
367 tx->tx_open_time = gethrtime();
368
369 DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg);
370 DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg);
371
372 /*
373 * Now that we've incremented tx_open_txg, we can let threads
374 * enter the next transaction group.
375 */
376 for (c = 0; c < max_ncpus; c++)
377 mutex_exit(&tx->tx_cpu[c].tc_open_lock);
378
379 /*
380 * Quiesce the transaction group by waiting for everyone to txg_exit().
381 */
382 for (c = 0; c < max_ncpus; c++) {
383 tx_cpu_t *tc = &tx->tx_cpu[c];
384 mutex_enter(&tc->tc_lock);
385 while (tc->tc_count[g] != 0)
386 cv_wait(&tc->tc_cv[g], &tc->tc_lock);
387 mutex_exit(&tc->tc_lock);
388 }
389 }
390
391 static void
392 txg_do_callbacks(list_t *cb_list)
393 {
394 dmu_tx_do_callbacks(cb_list, 0);
395
396 list_destroy(cb_list);
397
398 kmem_free(cb_list, sizeof (list_t));
399 }
400
401 /*
402 * Dispatch the commit callbacks registered on this txg to worker threads.
403 *
404 * If no callbacks are registered for a given TXG, nothing happens.
405 * This function creates a taskq for the associated pool, if needed.
406 */
407 static void
408 txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
409 {
410 int c;
411 tx_state_t *tx = &dp->dp_tx;
412 list_t *cb_list;
413
414 for (c = 0; c < max_ncpus; c++) {
415 tx_cpu_t *tc = &tx->tx_cpu[c];
416 /*
417 * No need to lock tx_cpu_t at this point, since this can
418 * only be called once a txg has been synced.
419 */
420
421 int g = txg & TXG_MASK;
422
423 if (list_is_empty(&tc->tc_callbacks[g]))
424 continue;
425
426 if (tx->tx_commit_cb_taskq == NULL) {
427 /*
428 * Commit callback taskq hasn't been created yet.
429 */
430 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
431 max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
432 TASKQ_PREPOPULATE);
433 }
434
435 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
436 list_create(cb_list, sizeof (dmu_tx_callback_t),
437 offsetof(dmu_tx_callback_t, dcb_node));
438
439 list_move_tail(cb_list, &tc->tc_callbacks[g]);
440
441 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
442 txg_do_callbacks, cb_list, TQ_SLEEP);
443 }
444 }
445
446 static void
447 txg_sync_thread(dsl_pool_t *dp)
448 {
449 spa_t *spa = dp->dp_spa;
450 tx_state_t *tx = &dp->dp_tx;
451 callb_cpr_t cpr;
452 uint64_t start, delta;
453
454 txg_thread_enter(tx, &cpr);
455
456 start = delta = 0;
457 for (;;) {
458 uint64_t timeout = zfs_txg_timeout * hz;
459 uint64_t timer;
460 uint64_t txg;
461
462 /*
463 * We sync when we're scanning, there's someone waiting
464 * on us, or the quiesce thread has handed off a txg to
465 * us, or we have reached our timeout.
466 */
467 timer = (delta >= timeout ? 0 : timeout - delta);
468 while (!dsl_scan_active(dp->dp_scan) &&
469 !tx->tx_exiting && timer > 0 &&
470 tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
471 tx->tx_quiesced_txg == 0 &&
472 dp->dp_dirty_total < zfs_dirty_data_sync) {
473 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
474 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
475 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
476 delta = ddi_get_lbolt() - start;
477 timer = (delta > timeout ? 0 : timeout - delta);
478 }
479
480 /*
481 * Wait until the quiesce thread hands off a txg to us,
482 * prompting it to do so if necessary.
483 */
484 while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) {
485 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
486 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
487 cv_broadcast(&tx->tx_quiesce_more_cv);
488 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
489 }
490
491 if (tx->tx_exiting)
492 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
493
494 /*
495 * Consume the quiesced txg which has been handed off to
496 * us. This may cause the quiescing thread to now be
497 * able to quiesce another txg, so we must signal it.
498 */
499 txg = tx->tx_quiesced_txg;
500 tx->tx_quiesced_txg = 0;
501 tx->tx_syncing_txg = txg;
502 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
503 cv_broadcast(&tx->tx_quiesce_more_cv);
504
505 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
506 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
507 mutex_exit(&tx->tx_sync_lock);
508
509 start = ddi_get_lbolt();
510 spa_sync(spa, txg);
511 delta = ddi_get_lbolt() - start;
512
513 mutex_enter(&tx->tx_sync_lock);
514 tx->tx_synced_txg = txg;
515 tx->tx_syncing_txg = 0;
516 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
517 cv_broadcast(&tx->tx_sync_done_cv);
518
519 /*
520 * Dispatch commit callbacks to worker threads.
521 */
522 txg_dispatch_callbacks(dp, txg);
523 }
524 }
525
526 static void
527 txg_quiesce_thread(dsl_pool_t *dp)
528 {
529 tx_state_t *tx = &dp->dp_tx;
530 callb_cpr_t cpr;
531
532 txg_thread_enter(tx, &cpr);
533
534 for (;;) {
535 uint64_t txg;
536
537 /*
538 * We quiesce when there's someone waiting on us.
539 * However, we can only have one txg in "quiescing" or
540 * "quiesced, waiting to sync" state. So we wait until
541 * the "quiesced, waiting to sync" txg has been consumed
542 * by the sync thread.
543 */
544 while (!tx->tx_exiting &&
545 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
546 tx->tx_quiesced_txg != 0))
547 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
548
549 if (tx->tx_exiting)
550 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
551
552 txg = tx->tx_open_txg;
553 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
554 txg, tx->tx_quiesce_txg_waiting,
555 tx->tx_sync_txg_waiting);
556 mutex_exit(&tx->tx_sync_lock);
557 txg_quiesce(dp, txg);
558 mutex_enter(&tx->tx_sync_lock);
559
560 /*
561 * Hand this txg off to the sync thread.
562 */
563 dprintf("quiesce done, handing off txg %llu\n", txg);
564 tx->tx_quiesced_txg = txg;
565 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
566 cv_broadcast(&tx->tx_sync_more_cv);
567 cv_broadcast(&tx->tx_quiesce_done_cv);
568 }
569 }
570
571 /*
572 * Delay this thread by delay nanoseconds if we are still in the open
573 * transaction group and there is already a waiting txg quiescing or quiesced.
574 * Abort the delay if this txg stalls or enters the quiescing state.
575 */
576 void
577 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
578 {
579 tx_state_t *tx = &dp->dp_tx;
580 hrtime_t start = gethrtime();
581
582 /* don't delay if this txg could transition to quiescing immediately */
583 if (tx->tx_open_txg > txg ||
584 tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
585 return;
586
587 mutex_enter(&tx->tx_sync_lock);
588 if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
589 mutex_exit(&tx->tx_sync_lock);
590 return;
591 }
592
593 while (gethrtime() - start < delay &&
594 tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) {
595 (void) cv_timedwait_hires(&tx->tx_quiesce_more_cv,
596 &tx->tx_sync_lock, delay, resolution, 0);
597 }
598
599 mutex_exit(&tx->tx_sync_lock);
600 }
601
602 void
603 txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
604 {
605 tx_state_t *tx = &dp->dp_tx;
606
607 ASSERT(!dsl_pool_config_held(dp));
608
609 mutex_enter(&tx->tx_sync_lock);
610 ASSERT(tx->tx_threads == 2);
611 if (txg == 0)
612 txg = tx->tx_open_txg + TXG_DEFER_SIZE;
613 if (tx->tx_sync_txg_waiting < txg)
614 tx->tx_sync_txg_waiting = txg;
615 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
616 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
617 while (tx->tx_synced_txg < txg) {
618 dprintf("broadcasting sync more "
619 "tx_synced=%llu waiting=%llu dp=%p\n",
620 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
621 cv_broadcast(&tx->tx_sync_more_cv);
622 cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
623 }
624 mutex_exit(&tx->tx_sync_lock);
625 }
626
627 void
628 txg_wait_open(dsl_pool_t *dp, uint64_t txg)
629 {
630 tx_state_t *tx = &dp->dp_tx;
631
632 ASSERT(!dsl_pool_config_held(dp));
633
634 mutex_enter(&tx->tx_sync_lock);
635 ASSERT(tx->tx_threads == 2);
636 if (txg == 0)
637 txg = tx->tx_open_txg + 1;
638 if (tx->tx_quiesce_txg_waiting < txg)
639 tx->tx_quiesce_txg_waiting = txg;
640 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
641 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
642 while (tx->tx_open_txg < txg) {
643 cv_broadcast(&tx->tx_quiesce_more_cv);
644 cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
645 }
646 mutex_exit(&tx->tx_sync_lock);
647 }
648
649 /*
650 * If there isn't a txg syncing or in the pipeline, push another txg through
651 * the pipeline by queiscing the open txg.
652 */
653 void
654 txg_kick(dsl_pool_t *dp)
655 {
656 tx_state_t *tx = &dp->dp_tx;
657
658 ASSERT(!dsl_pool_config_held(dp));
659
660 mutex_enter(&tx->tx_sync_lock);
661 if (tx->tx_syncing_txg == 0 &&
662 tx->tx_quiesce_txg_waiting <= tx->tx_open_txg &&
663 tx->tx_sync_txg_waiting <= tx->tx_synced_txg &&
664 tx->tx_quiesced_txg <= tx->tx_synced_txg) {
665 tx->tx_quiesce_txg_waiting = tx->tx_open_txg + 1;
666 cv_broadcast(&tx->tx_quiesce_more_cv);
667 }
668 mutex_exit(&tx->tx_sync_lock);
669 }
670
671 boolean_t
672 txg_stalled(dsl_pool_t *dp)
673 {
674 tx_state_t *tx = &dp->dp_tx;
675 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
676 }
677
678 boolean_t
679 txg_sync_waiting(dsl_pool_t *dp)
680 {
681 tx_state_t *tx = &dp->dp_tx;
682
683 return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
684 tx->tx_quiesced_txg != 0);
685 }
686
687 /*
688 * Per-txg object lists.
689 */
690 void
691 txg_list_create(txg_list_t *tl, size_t offset)
692 {
693 int t;
694
695 mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
696
697 tl->tl_offset = offset;
698
699 for (t = 0; t < TXG_SIZE; t++)
700 tl->tl_head[t] = NULL;
701 }
702
703 void
704 txg_list_destroy(txg_list_t *tl)
705 {
706 int t;
707
708 for (t = 0; t < TXG_SIZE; t++)
709 ASSERT(txg_list_empty(tl, t));
710
711 mutex_destroy(&tl->tl_lock);
712 }
713
714 boolean_t
715 txg_list_empty(txg_list_t *tl, uint64_t txg)
716 {
717 return (tl->tl_head[txg & TXG_MASK] == NULL);
718 }
719
720 /*
721 * Add an entry to the list (unless it's already on the list).
722 * Returns B_TRUE if it was actually added.
723 */
724 boolean_t
725 txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
726 {
727 int t = txg & TXG_MASK;
728 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
729 boolean_t add;
730
731 mutex_enter(&tl->tl_lock);
732 add = (tn->tn_member[t] == 0);
733 if (add) {
734 tn->tn_member[t] = 1;
735 tn->tn_next[t] = tl->tl_head[t];
736 tl->tl_head[t] = tn;
737 }
738 mutex_exit(&tl->tl_lock);
739
740 return (add);
741 }
742
743 /*
744 * Add an entry to the end of the list, unless it's already on the list.
745 * (walks list to find end)
746 * Returns B_TRUE if it was actually added.
747 */
748 boolean_t
749 txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg)
750 {
751 int t = txg & TXG_MASK;
752 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
753 boolean_t add;
754
755 mutex_enter(&tl->tl_lock);
756 add = (tn->tn_member[t] == 0);
757 if (add) {
758 txg_node_t **tp;
759
760 for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t])
761 continue;
762
763 tn->tn_member[t] = 1;
764 tn->tn_next[t] = NULL;
765 *tp = tn;
766 }
767 mutex_exit(&tl->tl_lock);
768
769 return (add);
770 }
771
772 /*
773 * Remove the head of the list and return it.
774 */
775 void *
776 txg_list_remove(txg_list_t *tl, uint64_t txg)
777 {
778 int t = txg & TXG_MASK;
779 txg_node_t *tn;
780 void *p = NULL;
781
782 mutex_enter(&tl->tl_lock);
783 if ((tn = tl->tl_head[t]) != NULL) {
784 p = (char *)tn - tl->tl_offset;
785 tl->tl_head[t] = tn->tn_next[t];
786 tn->tn_next[t] = NULL;
787 tn->tn_member[t] = 0;
788 }
789 mutex_exit(&tl->tl_lock);
790
791 return (p);
792 }
793
794 /*
795 * Remove a specific item from the list and return it.
796 */
797 void *
798 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
799 {
800 int t = txg & TXG_MASK;
801 txg_node_t *tn, **tp;
802
803 mutex_enter(&tl->tl_lock);
804
805 for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
806 if ((char *)tn - tl->tl_offset == p) {
807 *tp = tn->tn_next[t];
808 tn->tn_next[t] = NULL;
809 tn->tn_member[t] = 0;
810 mutex_exit(&tl->tl_lock);
811 return (p);
812 }
813 }
814
815 mutex_exit(&tl->tl_lock);
816
817 return (NULL);
818 }
819
820 boolean_t
821 txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
822 {
823 int t = txg & TXG_MASK;
824 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
825
826 return (tn->tn_member[t] != 0);
827 }
828
829 /*
830 * Walk a txg list -- only safe if you know it's not changing.
831 */
832 void *
833 txg_list_head(txg_list_t *tl, uint64_t txg)
834 {
835 int t = txg & TXG_MASK;
836 txg_node_t *tn = tl->tl_head[t];
837
838 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
839 }
840
841 void *
842 txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
843 {
844 int t = txg & TXG_MASK;
845 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
846
847 tn = tn->tn_next[t];
848
849 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
850 }