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 <mm (at) FreeBSD.org> 24 * Copyright (c) 2012, 2014 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(void *arg); 109 static void txg_quiesce_thread(void *arg); 110 111 int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */ 112 113 SYSCTL_DECL(_vfs_zfs); 114 SYSCTL_NODE(_vfs_zfs, OID_AUTO, txg, CTLFLAG_RW, 0, "ZFS TXG"); 115 SYSCTL_INT(_vfs_zfs_txg, OID_AUTO, timeout, CTLFLAG_RWTUN, &zfs_txg_timeout, 0, 116 "Maximum seconds worth of delta per txg"); 117 118 /* 119 * Prepare the txg subsystem. 120 */ 121 void 122 txg_init(dsl_pool_t *dp, uint64_t txg) 123 { 124 tx_state_t *tx = &dp->dp_tx; 125 int c; 126 bzero(tx, sizeof (tx_state_t)); 127 128 tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP); 129 130 for (c = 0; c < max_ncpus; c++) { 131 int i; 132 133 mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL); 134 mutex_init(&tx->tx_cpu[c].tc_open_lock, NULL, MUTEX_DEFAULT, 135 NULL); 136 for (i = 0; i < TXG_SIZE; i++) { 137 cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT, 138 NULL); 139 list_create(&tx->tx_cpu[c].tc_callbacks[i], 140 sizeof (dmu_tx_callback_t), 141 offsetof(dmu_tx_callback_t, dcb_node)); 142 } 143 } 144 145 mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL); 146 147 cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL); 148 cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL); 149 cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL); 150 cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL); 151 cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL); 152 153 tx->tx_open_txg = txg; 154 } 155 156 /* 157 * Close down the txg subsystem. 158 */ 159 void 160 txg_fini(dsl_pool_t *dp) 161 { 162 tx_state_t *tx = &dp->dp_tx; 163 int c; 164 165 ASSERT(tx->tx_threads == 0); 166 167 mutex_destroy(&tx->tx_sync_lock); 168 169 cv_destroy(&tx->tx_sync_more_cv); 170 cv_destroy(&tx->tx_sync_done_cv); 171 cv_destroy(&tx->tx_quiesce_more_cv); 172 cv_destroy(&tx->tx_quiesce_done_cv); 173 cv_destroy(&tx->tx_exit_cv); 174 175 for (c = 0; c < max_ncpus; c++) { 176 int i; 177 178 mutex_destroy(&tx->tx_cpu[c].tc_open_lock); 179 mutex_destroy(&tx->tx_cpu[c].tc_lock); 180 for (i = 0; i < TXG_SIZE; i++) { 181 cv_destroy(&tx->tx_cpu[c].tc_cv[i]); 182 list_destroy(&tx->tx_cpu[c].tc_callbacks[i]); 183 } 184 } 185 186 if (tx->tx_commit_cb_taskq != NULL) 187 taskq_destroy(tx->tx_commit_cb_taskq); 188 189 kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t)); 190 191 bzero(tx, sizeof (tx_state_t)); 192 } 193 194 /* 195 * Start syncing transaction groups. 196 */ 197 void 198 txg_sync_start(dsl_pool_t *dp) 199 { 200 tx_state_t *tx = &dp->dp_tx; 201 202 mutex_enter(&tx->tx_sync_lock); 203 204 dprintf("pool %p\n", dp); 205 206 ASSERT(tx->tx_threads == 0); 207 208 tx->tx_threads = 2; 209 210 tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread, 211 dp, 0, &p0, TS_RUN, minclsyspri); 212 213 /* 214 * The sync thread can need a larger-than-default stack size on 215 * 32-bit x86. This is due in part to nested pools and 216 * scrub_visitbp() recursion. 217 */ 218 tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread, 219 dp, 0, &p0, TS_RUN, minclsyspri); 220 221 mutex_exit(&tx->tx_sync_lock); 222 } 223 224 static void 225 txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr) 226 { 227 CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG); 228 mutex_enter(&tx->tx_sync_lock); 229 } 230 231 static void 232 txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp) 233 { 234 ASSERT(*tpp != NULL); 235 *tpp = NULL; 236 tx->tx_threads--; 237 cv_broadcast(&tx->tx_exit_cv); 238 CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */ 239 thread_exit(); 240 } 241 242 static void 243 txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time) 244 { 245 CALLB_CPR_SAFE_BEGIN(cpr); 246 247 if (time) 248 (void) cv_timedwait(cv, &tx->tx_sync_lock, time); 249 else 250 cv_wait(cv, &tx->tx_sync_lock); 251 252 CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock); 253 } 254 255 /* 256 * Stop syncing transaction groups. 257 */ 258 void 259 txg_sync_stop(dsl_pool_t *dp) 260 { 261 tx_state_t *tx = &dp->dp_tx; 262 263 dprintf("pool %p\n", dp); 264 /* 265 * Finish off any work in progress. 266 */ 267 ASSERT(tx->tx_threads == 2); 268 269 /* 270 * We need to ensure that we've vacated the deferred space_maps. 271 */ 272 txg_wait_synced(dp, tx->tx_open_txg + TXG_DEFER_SIZE); 273 274 /* 275 * Wake all sync threads and wait for them to die. 276 */ 277 mutex_enter(&tx->tx_sync_lock); 278 279 ASSERT(tx->tx_threads == 2); 280 281 tx->tx_exiting = 1; 282 283 cv_broadcast(&tx->tx_quiesce_more_cv); 284 cv_broadcast(&tx->tx_quiesce_done_cv); 285 cv_broadcast(&tx->tx_sync_more_cv); 286 287 while (tx->tx_threads != 0) 288 cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock); 289 290 tx->tx_exiting = 0; 291 292 mutex_exit(&tx->tx_sync_lock); 293 } 294 295 uint64_t 296 txg_hold_open(dsl_pool_t *dp, txg_handle_t *th) 297 { 298 tx_state_t *tx = &dp->dp_tx; 299 tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID]; 300 uint64_t txg; 301 302 mutex_enter(&tc->tc_open_lock); 303 txg = tx->tx_open_txg; 304 305 mutex_enter(&tc->tc_lock); 306 tc->tc_count[txg & TXG_MASK]++; 307 mutex_exit(&tc->tc_lock); 308 309 th->th_cpu = tc; 310 th->th_txg = txg; 311 312 return (txg); 313 } 314 315 void 316 txg_rele_to_quiesce(txg_handle_t *th) 317 { 318 tx_cpu_t *tc = th->th_cpu; 319 320 ASSERT(!MUTEX_HELD(&tc->tc_lock)); 321 mutex_exit(&tc->tc_open_lock); 322 } 323 324 void 325 txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks) 326 { 327 tx_cpu_t *tc = th->th_cpu; 328 int g = th->th_txg & TXG_MASK; 329 330 mutex_enter(&tc->tc_lock); 331 list_move_tail(&tc->tc_callbacks[g], tx_callbacks); 332 mutex_exit(&tc->tc_lock); 333 } 334 335 void 336 txg_rele_to_sync(txg_handle_t *th) 337 { 338 tx_cpu_t *tc = th->th_cpu; 339 int g = th->th_txg & TXG_MASK; 340 341 mutex_enter(&tc->tc_lock); 342 ASSERT(tc->tc_count[g] != 0); 343 if (--tc->tc_count[g] == 0) 344 cv_broadcast(&tc->tc_cv[g]); 345 mutex_exit(&tc->tc_lock); 346 347 th->th_cpu = NULL; /* defensive */ 348 } 349 350 /* 351 * Blocks until all transactions in the group are committed. 352 * 353 * On return, the transaction group has reached a stable state in which it can 354 * then be passed off to the syncing context. 355 */ 356 static __noinline void 357 txg_quiesce(dsl_pool_t *dp, uint64_t txg) 358 { 359 tx_state_t *tx = &dp->dp_tx; 360 int g = txg & TXG_MASK; 361 int c; 362 363 /* 364 * Grab all tc_open_locks so nobody else can get into this txg. 365 */ 366 for (c = 0; c < max_ncpus; c++) 367 mutex_enter(&tx->tx_cpu[c].tc_open_lock); 368 369 ASSERT(txg == tx->tx_open_txg); 370 tx->tx_open_txg++; 371 tx->tx_open_time = gethrtime(); 372 373 DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg); 374 DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg); 375 376 /* 377 * Now that we've incremented tx_open_txg, we can let threads 378 * enter the next transaction group. 379 */ 380 for (c = 0; c < max_ncpus; c++) 381 mutex_exit(&tx->tx_cpu[c].tc_open_lock); 382 383 /* 384 * Quiesce the transaction group by waiting for everyone to txg_exit(). 385 */ 386 for (c = 0; c < max_ncpus; c++) { 387 tx_cpu_t *tc = &tx->tx_cpu[c]; 388 mutex_enter(&tc->tc_lock); 389 while (tc->tc_count[g] != 0) 390 cv_wait(&tc->tc_cv[g], &tc->tc_lock); 391 mutex_exit(&tc->tc_lock); 392 } 393 } 394 395 static void 396 txg_do_callbacks(void *arg) 397 { 398 list_t *cb_list = arg; 399 400 dmu_tx_do_callbacks(cb_list, 0); 401 402 list_destroy(cb_list); 403 404 kmem_free(cb_list, sizeof (list_t)); 405 } 406 407 /* 408 * Dispatch the commit callbacks registered on this txg to worker threads. 409 * 410 * If no callbacks are registered for a given TXG, nothing happens. 411 * This function creates a taskq for the associated pool, if needed. 412 */ 413 static void 414 txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg) 415 { 416 int c; 417 tx_state_t *tx = &dp->dp_tx; 418 list_t *cb_list; 419 420 for (c = 0; c < max_ncpus; c++) { 421 tx_cpu_t *tc = &tx->tx_cpu[c]; 422 /* 423 * No need to lock tx_cpu_t at this point, since this can 424 * only be called once a txg has been synced. 425 */ 426 427 int g = txg & TXG_MASK; 428 429 if (list_is_empty(&tc->tc_callbacks[g])) 430 continue; 431 432 if (tx->tx_commit_cb_taskq == NULL) { 433 /* 434 * Commit callback taskq hasn't been created yet. 435 */ 436 tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb", 437 max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2, 438 TASKQ_PREPOPULATE); 439 } 440 441 cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP); 442 list_create(cb_list, sizeof (dmu_tx_callback_t), 443 offsetof(dmu_tx_callback_t, dcb_node)); 444 445 list_move_tail(cb_list, &tc->tc_callbacks[g]); 446 447 (void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *) 448 txg_do_callbacks, cb_list, TQ_SLEEP); 449 } 450 } 451 452 static void 453 txg_sync_thread(void *arg) 454 { 455 dsl_pool_t *dp = arg; 456 spa_t *spa = dp->dp_spa; 457 tx_state_t *tx = &dp->dp_tx; 458 callb_cpr_t cpr; 459 uint64_t start, delta; 460 461 txg_thread_enter(tx, &cpr); 462 463 start = delta = 0; 464 for (;;) { 465 uint64_t timeout = zfs_txg_timeout * hz; 466 uint64_t timer; 467 uint64_t txg; 468 469 /* 470 * We sync when we're scanning, there's someone waiting 471 * on us, or the quiesce thread has handed off a txg to 472 * us, or we have reached our timeout. 473 */ 474 timer = (delta >= timeout ? 0 : timeout - delta); 475 while (!dsl_scan_active(dp->dp_scan) && 476 !tx->tx_exiting && timer > 0 && 477 tx->tx_synced_txg >= tx->tx_sync_txg_waiting && 478 tx->tx_quiesced_txg == 0 && 479 dp->dp_dirty_total < zfs_dirty_data_sync) { 480 dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n", 481 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp); 482 txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer); 483 delta = ddi_get_lbolt() - start; 484 timer = (delta > timeout ? 0 : timeout - delta); 485 } 486 487 /* 488 * Wait until the quiesce thread hands off a txg to us, 489 * prompting it to do so if necessary. 490 */ 491 while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) { 492 if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1) 493 tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1; 494 cv_broadcast(&tx->tx_quiesce_more_cv); 495 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0); 496 } 497 498 if (tx->tx_exiting) 499 txg_thread_exit(tx, &cpr, &tx->tx_sync_thread); 500 501 /* 502 * Consume the quiesced txg which has been handed off to 503 * us. This may cause the quiescing thread to now be 504 * able to quiesce another txg, so we must signal it. 505 */ 506 txg = tx->tx_quiesced_txg; 507 tx->tx_quiesced_txg = 0; 508 tx->tx_syncing_txg = txg; 509 DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg); 510 cv_broadcast(&tx->tx_quiesce_more_cv); 511 512 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n", 513 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting); 514 mutex_exit(&tx->tx_sync_lock); 515 516 start = ddi_get_lbolt(); 517 spa_sync(spa, txg); 518 delta = ddi_get_lbolt() - start; 519 520 mutex_enter(&tx->tx_sync_lock); 521 tx->tx_synced_txg = txg; 522 tx->tx_syncing_txg = 0; 523 DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg); 524 cv_broadcast(&tx->tx_sync_done_cv); 525 526 /* 527 * Dispatch commit callbacks to worker threads. 528 */ 529 txg_dispatch_callbacks(dp, txg); 530 } 531 } 532 533 static void 534 txg_quiesce_thread(void *arg) 535 { 536 dsl_pool_t *dp = arg; 537 tx_state_t *tx = &dp->dp_tx; 538 callb_cpr_t cpr; 539 540 txg_thread_enter(tx, &cpr); 541 542 for (;;) { 543 uint64_t txg; 544 545 /* 546 * We quiesce when there's someone waiting on us. 547 * However, we can only have one txg in "quiescing" or 548 * "quiesced, waiting to sync" state. So we wait until 549 * the "quiesced, waiting to sync" txg has been consumed 550 * by the sync thread. 551 */ 552 while (!tx->tx_exiting && 553 (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting || 554 tx->tx_quiesced_txg != 0)) 555 txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0); 556 557 if (tx->tx_exiting) 558 txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread); 559 560 txg = tx->tx_open_txg; 561 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n", 562 txg, tx->tx_quiesce_txg_waiting, 563 tx->tx_sync_txg_waiting); 564 mutex_exit(&tx->tx_sync_lock); 565 txg_quiesce(dp, txg); 566 mutex_enter(&tx->tx_sync_lock); 567 568 /* 569 * Hand this txg off to the sync thread. 570 */ 571 dprintf("quiesce done, handing off txg %llu\n", txg); 572 tx->tx_quiesced_txg = txg; 573 DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg); 574 cv_broadcast(&tx->tx_sync_more_cv); 575 cv_broadcast(&tx->tx_quiesce_done_cv); 576 } 577 } 578 579 /* 580 * Delay this thread by delay nanoseconds if we are still in the open 581 * transaction group and there is already a waiting txg quiesing or quiesced. 582 * Abort the delay if this txg stalls or enters the quiesing state. 583 */ 584 void 585 txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution) 586 { 587 tx_state_t *tx = &dp->dp_tx; 588 hrtime_t start = gethrtime(); 589 590 /* don't delay if this txg could transition to quiescing immediately */ 591 if (tx->tx_open_txg > txg || 592 tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1) 593 return; 594 595 mutex_enter(&tx->tx_sync_lock); 596 if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) { 597 mutex_exit(&tx->tx_sync_lock); 598 return; 599 } 600 601 while (gethrtime() - start < delay && 602 tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) { 603 (void) cv_timedwait_hires(&tx->tx_quiesce_more_cv, 604 &tx->tx_sync_lock, delay, resolution, 0); 605 } 606 607 mutex_exit(&tx->tx_sync_lock); 608 } 609 610 void 611 txg_wait_synced(dsl_pool_t *dp, uint64_t txg) 612 { 613 tx_state_t *tx = &dp->dp_tx; 614 615 ASSERT(!dsl_pool_config_held(dp)); 616 617 mutex_enter(&tx->tx_sync_lock); 618 ASSERT(tx->tx_threads == 2); 619 if (txg == 0) 620 txg = tx->tx_open_txg + TXG_DEFER_SIZE; 621 if (tx->tx_sync_txg_waiting < txg) 622 tx->tx_sync_txg_waiting = txg; 623 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n", 624 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting); 625 while (tx->tx_synced_txg < txg) { 626 dprintf("broadcasting sync more " 627 "tx_synced=%llu waiting=%llu dp=%p\n", 628 tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp); 629 cv_broadcast(&tx->tx_sync_more_cv); 630 cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock); 631 } 632 mutex_exit(&tx->tx_sync_lock); 633 } 634 635 void 636 txg_wait_open(dsl_pool_t *dp, uint64_t txg) 637 { 638 tx_state_t *tx = &dp->dp_tx; 639 640 ASSERT(!dsl_pool_config_held(dp)); 641 642 mutex_enter(&tx->tx_sync_lock); 643 ASSERT(tx->tx_threads == 2); 644 if (txg == 0) 645 txg = tx->tx_open_txg + 1; 646 if (tx->tx_quiesce_txg_waiting < txg) 647 tx->tx_quiesce_txg_waiting = txg; 648 dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n", 649 txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting); 650 while (tx->tx_open_txg < txg) { 651 cv_broadcast(&tx->tx_quiesce_more_cv); 652 cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock); 653 } 654 mutex_exit(&tx->tx_sync_lock); 655 } 656 657 /* 658 * If there isn't a txg syncing or in the pipeline, push another txg through 659 * the pipeline by queiscing the open txg. 660 */ 661 void 662 txg_kick(dsl_pool_t *dp) 663 { 664 tx_state_t *tx = &dp->dp_tx; 665 666 ASSERT(!dsl_pool_config_held(dp)); 667 668 mutex_enter(&tx->tx_sync_lock); 669 if (tx->tx_syncing_txg == 0 && 670 tx->tx_quiesce_txg_waiting <= tx->tx_open_txg && 671 tx->tx_sync_txg_waiting <= tx->tx_synced_txg && 672 tx->tx_quiesced_txg <= tx->tx_synced_txg) { 673 tx->tx_quiesce_txg_waiting = tx->tx_open_txg + 1; 674 cv_broadcast(&tx->tx_quiesce_more_cv); 675 } 676 mutex_exit(&tx->tx_sync_lock); 677 } 678 679 boolean_t 680 txg_stalled(dsl_pool_t *dp) 681 { 682 tx_state_t *tx = &dp->dp_tx; 683 return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg); 684 } 685 686 boolean_t 687 txg_sync_waiting(dsl_pool_t *dp) 688 { 689 tx_state_t *tx = &dp->dp_tx; 690 691 return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting || 692 tx->tx_quiesced_txg != 0); 693 } 694 695 /* 696 * Per-txg object lists. 697 */ 698 void 699 txg_list_create(txg_list_t *tl, size_t offset) 700 { 701 int t; 702 703 mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL); 704 705 tl->tl_offset = offset; 706 707 for (t = 0; t < TXG_SIZE; t++) 708 tl->tl_head[t] = NULL; 709 } 710 711 void 712 txg_list_destroy(txg_list_t *tl) 713 { 714 int t; 715 716 for (t = 0; t < TXG_SIZE; t++) 717 ASSERT(txg_list_empty(tl, t)); 718 719 mutex_destroy(&tl->tl_lock); 720 } 721 722 boolean_t 723 txg_list_empty(txg_list_t *tl, uint64_t txg) 724 { 725 return (tl->tl_head[txg & TXG_MASK] == NULL); 726 } 727 728 /* 729 * Returns true if all txg lists are empty. 730 * 731 * Warning: this is inherently racy (an item could be added immediately after this 732 * function returns). We don't bother with the lock because it wouldn't change the 733 * semantics. 734 */ 735 boolean_t 736 txg_all_lists_empty(txg_list_t *tl) 737 { 738 for (int i = 0; i < TXG_SIZE; i++) { 739 if (!txg_list_empty(tl, i)) { 740 return (B_FALSE); 741 } 742 } 743 return (B_TRUE); 744 } 745 746 /* 747 * Add an entry to the list (unless it's already on the list). 748 * Returns B_TRUE if it was actually added. 749 */ 750 boolean_t 751 txg_list_add(txg_list_t *tl, void *p, uint64_t txg) 752 { 753 int t = txg & TXG_MASK; 754 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset); 755 boolean_t add; 756 757 mutex_enter(&tl->tl_lock); 758 add = (tn->tn_member[t] == 0); 759 if (add) { 760 tn->tn_member[t] = 1; 761 tn->tn_next[t] = tl->tl_head[t]; 762 tl->tl_head[t] = tn; 763 } 764 mutex_exit(&tl->tl_lock); 765 766 return (add); 767 } 768 769 /* 770 * Add an entry to the end of the list, unless it's already on the list. 771 * (walks list to find end) 772 * Returns B_TRUE if it was actually added. 773 */ 774 boolean_t 775 txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg) 776 { 777 int t = txg & TXG_MASK; 778 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset); 779 boolean_t add; 780 781 mutex_enter(&tl->tl_lock); 782 add = (tn->tn_member[t] == 0); 783 if (add) { 784 txg_node_t **tp; 785 786 for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t]) 787 continue; 788 789 tn->tn_member[t] = 1; 790 tn->tn_next[t] = NULL; 791 *tp = tn; 792 } 793 mutex_exit(&tl->tl_lock); 794 795 return (add); 796 } 797 798 /* 799 * Remove the head of the list and return it. 800 */ 801 void * 802 txg_list_remove(txg_list_t *tl, uint64_t txg) 803 { 804 int t = txg & TXG_MASK; 805 txg_node_t *tn; 806 void *p = NULL; 807 808 mutex_enter(&tl->tl_lock); 809 if ((tn = tl->tl_head[t]) != NULL) { 810 p = (char *)tn - tl->tl_offset; 811 tl->tl_head[t] = tn->tn_next[t]; 812 tn->tn_next[t] = NULL; 813 tn->tn_member[t] = 0; 814 } 815 mutex_exit(&tl->tl_lock); 816 817 return (p); 818 } 819 820 /* 821 * Remove a specific item from the list and return it. 822 */ 823 void * 824 txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg) 825 { 826 int t = txg & TXG_MASK; 827 txg_node_t *tn, **tp; 828 829 mutex_enter(&tl->tl_lock); 830 831 for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) { 832 if ((char *)tn - tl->tl_offset == p) { 833 *tp = tn->tn_next[t]; 834 tn->tn_next[t] = NULL; 835 tn->tn_member[t] = 0; 836 mutex_exit(&tl->tl_lock); 837 return (p); 838 } 839 } 840 841 mutex_exit(&tl->tl_lock); 842 843 return (NULL); 844 } 845 846 boolean_t 847 txg_list_member(txg_list_t *tl, void *p, uint64_t txg) 848 { 849 int t = txg & TXG_MASK; 850 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset); 851 852 return (tn->tn_member[t] != 0); 853 } 854 855 /* 856 * Walk a txg list -- only safe if you know it's not changing. 857 */ 858 void * 859 txg_list_head(txg_list_t *tl, uint64_t txg) 860 { 861 int t = txg & TXG_MASK; 862 txg_node_t *tn = tl->tl_head[t]; 863 864 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset); 865 } 866 867 void * 868 txg_list_next(txg_list_t *tl, void *p, uint64_t txg) 869 { 870 int t = txg & TXG_MASK; 871 txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset); 872 873 tn = tn->tn_next[t]; 874 875 return (tn == NULL ? NULL : (char *)tn - tl->tl_offset); 876 } 877
Indexes created Tue May 26 00:24:38 UTC 2026