1 /* 2 * Copyright (c) 2008 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/vfs/hammer/hammer_flusher.c,v 1.45 2008/07/31 04:42:04 dillon Exp $ 35 */ 36 /* 37 * HAMMER dependancy flusher thread 38 * 39 * Meta data updates create buffer dependancies which are arranged as a 40 * hierarchy of lists. 41 */ 42 43 #include "hammer.h" 44 45 static void hammer_flusher_master_thread(void *arg); 46 static void hammer_flusher_slave_thread(void *arg); 47 static void hammer_flusher_flush(hammer_mount_t hmp); 48 static void hammer_flusher_flush_inode(hammer_inode_t ip, 49 hammer_transaction_t trans); 50 51 RB_GENERATE(hammer_fls_rb_tree, hammer_inode, rb_flsnode, 52 hammer_ino_rb_compare); 53 54 /* 55 * Inodes are sorted and assigned to slave threads in groups of 128. 56 * We want a flush group size large enough such that the slave threads 57 * are not likely to interfere with each other when accessing the B-Tree, 58 * but not so large that we lose concurrency. 59 */ 60 #define HAMMER_FLUSH_GROUP_SIZE 128 61 62 /* 63 * Support structures for the flusher threads. 64 */ 65 struct hammer_flusher_info { 66 TAILQ_ENTRY(hammer_flusher_info) entry; 67 struct hammer_mount *hmp; 68 thread_t td; 69 int runstate; 70 int count; 71 hammer_flush_group_t flg; 72 hammer_inode_t work_array[HAMMER_FLUSH_GROUP_SIZE]; 73 }; 74 75 typedef struct hammer_flusher_info *hammer_flusher_info_t; 76 77 /* 78 * Sync all inodes pending on the flusher. 79 * 80 * All flush groups will be flushed. This does not queue dirty inodes 81 * to the flush groups, it just flushes out what has already been queued! 82 */ 83 void 84 hammer_flusher_sync(hammer_mount_t hmp) 85 { 86 int seq; 87 88 seq = hammer_flusher_async(hmp, NULL); 89 hammer_flusher_wait(hmp, seq); 90 } 91 92 /* 93 * Sync all inodes pending on the flusher - return immediately. 94 * 95 * All flush groups will be flushed. 96 */ 97 int 98 hammer_flusher_async(hammer_mount_t hmp, hammer_flush_group_t close_flg) 99 { 100 hammer_flush_group_t flg; 101 int seq = hmp->flusher.next; 102 103 TAILQ_FOREACH(flg, &hmp->flush_group_list, flush_entry) { 104 if (flg->running == 0) 105 ++seq; 106 flg->closed = 1; 107 if (flg == close_flg) 108 break; 109 } 110 if (hmp->flusher.td) { 111 if (hmp->flusher.signal++ == 0) 112 wakeup(&hmp->flusher.signal); 113 } else { 114 seq = hmp->flusher.done; 115 } 116 return(seq); 117 } 118 119 int 120 hammer_flusher_async_one(hammer_mount_t hmp) 121 { 122 int seq; 123 124 if (hmp->flusher.td) { 125 seq = hmp->flusher.next; 126 if (hmp->flusher.signal++ == 0) 127 wakeup(&hmp->flusher.signal); 128 } else { 129 seq = hmp->flusher.done; 130 } 131 return(seq); 132 } 133 134 /* 135 * Wait for the flusher to get to the specified sequence number. 136 * Signal the flusher as often as necessary to keep it going. 137 */ 138 void 139 hammer_flusher_wait(hammer_mount_t hmp, int seq) 140 { 141 while ((int)(seq - hmp->flusher.done) > 0) { 142 if (hmp->flusher.act != seq) { 143 if (hmp->flusher.signal++ == 0) 144 wakeup(&hmp->flusher.signal); 145 } 146 tsleep(&hmp->flusher.done, 0, "hmrfls", 0); 147 } 148 } 149 150 void 151 hammer_flusher_wait_next(hammer_mount_t hmp) 152 { 153 int seq; 154 155 seq = hammer_flusher_async_one(hmp); 156 hammer_flusher_wait(hmp, seq); 157 } 158 159 void 160 hammer_flusher_create(hammer_mount_t hmp) 161 { 162 hammer_flusher_info_t info; 163 int i; 164 165 hmp->flusher.signal = 0; 166 hmp->flusher.act = 0; 167 hmp->flusher.done = 0; 168 hmp->flusher.next = 1; 169 hammer_ref(&hmp->flusher.finalize_lock); 170 TAILQ_INIT(&hmp->flusher.run_list); 171 TAILQ_INIT(&hmp->flusher.ready_list); 172 173 lwkt_create(hammer_flusher_master_thread, hmp, 174 &hmp->flusher.td, NULL, 0, -1, "hammer-M"); 175 for (i = 0; i < HAMMER_MAX_FLUSHERS; ++i) { 176 info = kmalloc(sizeof(*info), hmp->m_misc, M_WAITOK|M_ZERO); 177 info->hmp = hmp; 178 TAILQ_INSERT_TAIL(&hmp->flusher.ready_list, info, entry); 179 lwkt_create(hammer_flusher_slave_thread, info, 180 &info->td, NULL, 0, -1, "hammer-S%d", i); 181 } 182 } 183 184 void 185 hammer_flusher_destroy(hammer_mount_t hmp) 186 { 187 hammer_flusher_info_t info; 188 189 /* 190 * Kill the master 191 */ 192 hmp->flusher.exiting = 1; 193 while (hmp->flusher.td) { 194 ++hmp->flusher.signal; 195 wakeup(&hmp->flusher.signal); 196 tsleep(&hmp->flusher.exiting, 0, "hmrwex", hz); 197 } 198 199 /* 200 * Kill the slaves 201 */ 202 while ((info = TAILQ_FIRST(&hmp->flusher.ready_list)) != NULL) { 203 KKASSERT(info->runstate == 0); 204 TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry); 205 info->runstate = -1; 206 wakeup(&info->runstate); 207 while (info->td) 208 tsleep(&info->td, 0, "hmrwwc", 0); 209 kfree(info, hmp->m_misc); 210 } 211 } 212 213 /* 214 * The master flusher thread manages the flusher sequence id and 215 * synchronization with the slave work threads. 216 */ 217 static void 218 hammer_flusher_master_thread(void *arg) 219 { 220 hammer_flush_group_t flg; 221 hammer_mount_t hmp; 222 223 hmp = arg; 224 225 lwkt_gettoken(&hmp->fs_token); 226 227 for (;;) { 228 /* 229 * Do at least one flush cycle. We may have to update the 230 * UNDO FIFO even if no inodes are queued. 231 */ 232 for (;;) { 233 while (hmp->flusher.group_lock) 234 tsleep(&hmp->flusher.group_lock, 0, "hmrhld", 0); 235 hmp->flusher.act = hmp->flusher.next; 236 ++hmp->flusher.next; 237 hammer_flusher_clean_loose_ios(hmp); 238 hammer_flusher_flush(hmp); 239 hmp->flusher.done = hmp->flusher.act; 240 wakeup(&hmp->flusher.done); 241 flg = TAILQ_FIRST(&hmp->flush_group_list); 242 if (flg == NULL || flg->closed == 0) 243 break; 244 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) 245 break; 246 } 247 248 /* 249 * Wait for activity. 250 */ 251 if (hmp->flusher.exiting && TAILQ_EMPTY(&hmp->flush_group_list)) 252 break; 253 while (hmp->flusher.signal == 0) 254 tsleep(&hmp->flusher.signal, 0, "hmrwwa", 0); 255 256 /* 257 * Flush for each count on signal but only allow one extra 258 * flush request to build up. 259 */ 260 if (--hmp->flusher.signal != 0) 261 hmp->flusher.signal = 1; 262 } 263 264 /* 265 * And we are done. 266 */ 267 hmp->flusher.td = NULL; 268 wakeup(&hmp->flusher.exiting); 269 lwkt_reltoken(&hmp->fs_token); 270 lwkt_exit(); 271 } 272 273 /* 274 * Flush all inodes in the current flush group. 275 */ 276 static void 277 hammer_flusher_flush(hammer_mount_t hmp) 278 { 279 hammer_flusher_info_t info; 280 hammer_flush_group_t flg; 281 hammer_reserve_t resv; 282 hammer_inode_t ip; 283 hammer_inode_t next_ip; 284 int slave_index; 285 int count; 286 287 /* 288 * Just in-case there's a flush race on mount 289 */ 290 if (TAILQ_FIRST(&hmp->flusher.ready_list) == NULL) 291 return; 292 293 /* 294 * We only do one flg but we may have to loop/retry. 295 */ 296 count = 0; 297 while ((flg = TAILQ_FIRST(&hmp->flush_group_list)) != NULL) { 298 ++count; 299 if (hammer_debug_general & 0x0001) { 300 kprintf("hammer_flush %d ttl=%d recs=%d\n", 301 hmp->flusher.act, 302 flg->total_count, flg->refs); 303 } 304 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) 305 break; 306 hammer_start_transaction_fls(&hmp->flusher.trans, hmp); 307 308 /* 309 * If the previous flush cycle just about exhausted our 310 * UNDO space we may have to do a dummy cycle to move the 311 * first_offset up before actually digging into a new cycle, 312 * or the new cycle will not have sufficient undo space. 313 */ 314 if (hammer_flusher_undo_exhausted(&hmp->flusher.trans, 3)) 315 hammer_flusher_finalize(&hmp->flusher.trans, 0); 316 317 /* 318 * Ok, we are running this flush group now (this prevents new 319 * additions to it). 320 */ 321 flg->running = 1; 322 if (hmp->next_flush_group == flg) 323 hmp->next_flush_group = TAILQ_NEXT(flg, flush_entry); 324 325 /* 326 * Iterate the inodes in the flg's flush_tree and assign 327 * them to slaves. 328 */ 329 slave_index = 0; 330 info = TAILQ_FIRST(&hmp->flusher.ready_list); 331 next_ip = RB_FIRST(hammer_fls_rb_tree, &flg->flush_tree); 332 333 while ((ip = next_ip) != NULL) { 334 next_ip = RB_NEXT(hammer_fls_rb_tree, 335 &flg->flush_tree, ip); 336 337 if (++hmp->check_yield > hammer_yield_check) { 338 hmp->check_yield = 0; 339 lwkt_yield(); 340 } 341 342 /* 343 * Add ip to the slave's work array. The slave is 344 * not currently running. 345 */ 346 info->work_array[info->count++] = ip; 347 if (info->count != HAMMER_FLUSH_GROUP_SIZE) 348 continue; 349 350 /* 351 * Get the slave running 352 */ 353 TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry); 354 TAILQ_INSERT_TAIL(&hmp->flusher.run_list, info, entry); 355 info->flg = flg; 356 info->runstate = 1; 357 wakeup(&info->runstate); 358 359 /* 360 * Get a new slave. We may have to wait for one to 361 * finish running. 362 */ 363 while ((info = TAILQ_FIRST(&hmp->flusher.ready_list)) == NULL) { 364 tsleep(&hmp->flusher.ready_list, 0, "hmrfcc", 0); 365 } 366 } 367 368 /* 369 * Run the current slave if necessary 370 */ 371 if (info->count) { 372 TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry); 373 TAILQ_INSERT_TAIL(&hmp->flusher.run_list, info, entry); 374 info->flg = flg; 375 info->runstate = 1; 376 wakeup(&info->runstate); 377 } 378 379 /* 380 * Wait for all slaves to finish running 381 */ 382 while (TAILQ_FIRST(&hmp->flusher.run_list) != NULL) 383 tsleep(&hmp->flusher.ready_list, 0, "hmrfcc", 0); 384 385 /* 386 * Do the final finalization, clean up 387 */ 388 hammer_flusher_finalize(&hmp->flusher.trans, 1); 389 hmp->flusher.tid = hmp->flusher.trans.tid; 390 391 hammer_done_transaction(&hmp->flusher.trans); 392 393 /* 394 * Loop up on the same flg. If the flg is done clean it up 395 * and break out. We only flush one flg. 396 */ 397 if (RB_EMPTY(&flg->flush_tree)) { 398 KKASSERT(flg->refs == 0); 399 TAILQ_REMOVE(&hmp->flush_group_list, flg, flush_entry); 400 kfree(flg, hmp->m_misc); 401 break; 402 } 403 } 404 405 /* 406 * We may have pure meta-data to flush, or we may have to finish 407 * cycling the UNDO FIFO, even if there were no flush groups. 408 */ 409 if (count == 0 && hammer_flusher_haswork(hmp)) { 410 hammer_start_transaction_fls(&hmp->flusher.trans, hmp); 411 hammer_flusher_finalize(&hmp->flusher.trans, 1); 412 hammer_done_transaction(&hmp->flusher.trans); 413 } 414 415 /* 416 * Clean up any freed big-blocks (typically zone-2). 417 * resv->flush_group is typically set several flush groups ahead 418 * of the free to ensure that the freed block is not reused until 419 * it can no longer be reused. 420 */ 421 while ((resv = TAILQ_FIRST(&hmp->delay_list)) != NULL) { 422 if (resv->flush_group != hmp->flusher.act) 423 break; 424 hammer_reserve_clrdelay(hmp, resv); 425 } 426 } 427 428 429 /* 430 * The slave flusher thread pulls work off the master flush list until no 431 * work is left. 432 */ 433 static void 434 hammer_flusher_slave_thread(void *arg) 435 { 436 hammer_flush_group_t flg; 437 hammer_flusher_info_t info; 438 hammer_mount_t hmp; 439 hammer_inode_t ip; 440 int i; 441 442 info = arg; 443 hmp = info->hmp; 444 lwkt_gettoken(&hmp->fs_token); 445 446 for (;;) { 447 while (info->runstate == 0) 448 tsleep(&info->runstate, 0, "hmrssw", 0); 449 if (info->runstate < 0) 450 break; 451 flg = info->flg; 452 453 for (i = 0; i < info->count; ++i) { 454 ip = info->work_array[i]; 455 hammer_flusher_flush_inode(ip, &hmp->flusher.trans); 456 ++hammer_stats_inode_flushes; 457 } 458 info->count = 0; 459 info->runstate = 0; 460 TAILQ_REMOVE(&hmp->flusher.run_list, info, entry); 461 TAILQ_INSERT_TAIL(&hmp->flusher.ready_list, info, entry); 462 wakeup(&hmp->flusher.ready_list); 463 } 464 info->td = NULL; 465 wakeup(&info->td); 466 lwkt_reltoken(&hmp->fs_token); 467 lwkt_exit(); 468 } 469 470 void 471 hammer_flusher_clean_loose_ios(hammer_mount_t hmp) 472 { 473 hammer_buffer_t buffer; 474 hammer_io_t io; 475 476 /* 477 * loose ends - buffers without bp's aren't tracked by the kernel 478 * and can build up, so clean them out. This can occur when an 479 * IO completes on a buffer with no references left. 480 * 481 * The io_token is needed to protect the list. 482 */ 483 if ((io = TAILQ_FIRST(&hmp->lose_list)) != NULL) { 484 lwkt_gettoken(&hmp->io_token); 485 while ((io = TAILQ_FIRST(&hmp->lose_list)) != NULL) { 486 KKASSERT(io->mod_list == &hmp->lose_list); 487 TAILQ_REMOVE(&hmp->lose_list, io, mod_entry); 488 io->mod_list = NULL; 489 hammer_ref(&io->lock); 490 buffer = (void *)io; 491 hammer_rel_buffer(buffer, 0); 492 } 493 lwkt_reltoken(&hmp->io_token); 494 } 495 } 496 497 /* 498 * Flush a single inode that is part of a flush group. 499 * 500 * Flusher errors are extremely serious, even ENOSPC shouldn't occur because 501 * the front-end should have reserved sufficient space on the media. Any 502 * error other then EWOULDBLOCK will force the mount to be read-only. 503 */ 504 static 505 void 506 hammer_flusher_flush_inode(hammer_inode_t ip, hammer_transaction_t trans) 507 { 508 hammer_mount_t hmp = ip->hmp; 509 int error; 510 511 hammer_flusher_clean_loose_ios(hmp); 512 error = hammer_sync_inode(trans, ip); 513 514 /* 515 * EWOULDBLOCK can happen under normal operation, all other errors 516 * are considered extremely serious. We must set WOULDBLOCK 517 * mechanics to deal with the mess left over from the abort of the 518 * previous flush. 519 */ 520 if (error) { 521 ip->flags |= HAMMER_INODE_WOULDBLOCK; 522 if (error == EWOULDBLOCK) 523 error = 0; 524 } 525 hammer_flush_inode_done(ip, error); 526 while (hmp->flusher.finalize_want) 527 tsleep(&hmp->flusher.finalize_want, 0, "hmrsxx", 0); 528 if (hammer_flusher_undo_exhausted(trans, 1)) { 529 kprintf("HAMMER: Warning: UNDO area too small!\n"); 530 hammer_flusher_finalize(trans, 1); 531 } else if (hammer_flusher_meta_limit(trans->hmp)) { 532 hammer_flusher_finalize(trans, 0); 533 } 534 } 535 536 /* 537 * Return non-zero if the UNDO area has less then (QUARTER / 4) of its 538 * space left. 539 * 540 * 1/4 - Emergency free undo space level. Below this point the flusher 541 * will finalize even if directory dependancies have not been resolved. 542 * 543 * 2/4 - Used by the pruning and reblocking code. These functions may be 544 * running in parallel with a flush and cannot be allowed to drop 545 * available undo space to emergency levels. 546 * 547 * 3/4 - Used at the beginning of a flush to force-sync the volume header 548 * to give the flush plenty of runway to work in. 549 */ 550 int 551 hammer_flusher_undo_exhausted(hammer_transaction_t trans, int quarter) 552 { 553 if (hammer_undo_space(trans) < 554 hammer_undo_max(trans->hmp) * quarter / 4) { 555 return(1); 556 } else { 557 return(0); 558 } 559 } 560 561 /* 562 * Flush all pending UNDOs, wait for write completion, update the volume 563 * header with the new UNDO end position, and flush it. Then 564 * asynchronously flush the meta-data. 565 * 566 * If this is the last finalization in a flush group we also synchronize 567 * our cached blockmap and set hmp->flusher_undo_start and our cached undo 568 * fifo first_offset so the next flush resets the FIFO pointers. 569 * 570 * If this is not final it is being called because too many dirty meta-data 571 * buffers have built up and must be flushed with UNDO synchronization to 572 * avoid a buffer cache deadlock. 573 */ 574 void 575 hammer_flusher_finalize(hammer_transaction_t trans, int final) 576 { 577 hammer_volume_t root_volume; 578 hammer_blockmap_t cundomap, dundomap; 579 hammer_mount_t hmp; 580 hammer_io_t io; 581 hammer_off_t save_undo_next_offset; 582 int count; 583 int i; 584 585 hmp = trans->hmp; 586 root_volume = trans->rootvol; 587 588 /* 589 * Exclusively lock the flusher. This guarantees that all dirty 590 * buffers will be idled (have a mod-count of 0). 591 */ 592 ++hmp->flusher.finalize_want; 593 hammer_lock_ex(&hmp->flusher.finalize_lock); 594 595 /* 596 * If this isn't the final sync several threads may have hit the 597 * meta-limit at the same time and raced. Only sync if we really 598 * have to, after acquiring the lock. 599 */ 600 if (final == 0 && !hammer_flusher_meta_limit(hmp)) 601 goto done; 602 603 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) 604 goto done; 605 606 /* 607 * Flush data buffers. This can occur asynchronously and at any 608 * time. We must interlock against the frontend direct-data write 609 * but do not have to acquire the sync-lock yet. 610 * 611 * These data buffers have already been collected prior to the 612 * related inode(s) getting queued to the flush group. 613 */ 614 count = 0; 615 while ((io = TAILQ_FIRST(&hmp->data_list)) != NULL) { 616 if (io->ioerror) 617 break; 618 hammer_ref(&io->lock); 619 hammer_io_write_interlock(io); 620 KKASSERT(io->type != HAMMER_STRUCTURE_VOLUME); 621 hammer_io_flush(io, 0); 622 hammer_io_done_interlock(io); 623 hammer_rel_buffer((hammer_buffer_t)io, 0); 624 hammer_io_limit_backlog(hmp); 625 ++count; 626 } 627 628 /* 629 * The sync-lock is required for the remaining sequence. This lock 630 * prevents meta-data from being modified. 631 */ 632 hammer_sync_lock_ex(trans); 633 634 /* 635 * If we have been asked to finalize the volume header sync the 636 * cached blockmap to the on-disk blockmap. Generate an UNDO 637 * record for the update. 638 */ 639 if (final) { 640 cundomap = &hmp->blockmap[0]; 641 dundomap = &root_volume->ondisk->vol0_blockmap[0]; 642 if (root_volume->io.modified) { 643 hammer_modify_volume(trans, root_volume, 644 dundomap, sizeof(hmp->blockmap)); 645 for (i = 0; i < HAMMER_MAX_ZONES; ++i) 646 hammer_crc_set_blockmap(&cundomap[i]); 647 bcopy(cundomap, dundomap, sizeof(hmp->blockmap)); 648 hammer_modify_volume_done(root_volume); 649 } 650 } 651 652 /* 653 * Flush UNDOs. This can occur concurrently with the data flush 654 * because data writes never overwrite. 655 * 656 * This also waits for I/Os to complete and flushes the cache on 657 * the target disk. 658 * 659 * Record the UNDO append point as this can continue to change 660 * after we have flushed the UNDOs. 661 */ 662 cundomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX]; 663 hammer_lock_ex(&hmp->undo_lock); 664 save_undo_next_offset = cundomap->next_offset; 665 hammer_unlock(&hmp->undo_lock); 666 hammer_flusher_flush_undos(hmp, HAMMER_FLUSH_UNDOS_FORCED); 667 668 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) 669 goto failed; 670 671 /* 672 * HAMMER VERSION < 4: 673 * Update the on-disk volume header with new UNDO FIFO end 674 * position (do not generate new UNDO records for this change). 675 * We have to do this for the UNDO FIFO whether (final) is 676 * set or not in order for the UNDOs to be recognized on 677 * recovery. 678 * 679 * HAMMER VERSION >= 4: 680 * The UNDO FIFO data written above will be recognized on 681 * recovery without us having to sync the volume header. 682 * 683 * Also update the on-disk next_tid field. This does not require 684 * an UNDO. However, because our TID is generated before we get 685 * the sync lock another sync may have beat us to the punch. 686 * 687 * This also has the side effect of updating first_offset based on 688 * a prior finalization when the first finalization of the next flush 689 * cycle occurs, removing any undo info from the prior finalization 690 * from consideration. 691 * 692 * The volume header will be flushed out synchronously. 693 */ 694 dundomap = &root_volume->ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX]; 695 cundomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX]; 696 697 if (dundomap->first_offset != cundomap->first_offset || 698 dundomap->next_offset != save_undo_next_offset) { 699 hammer_modify_volume(NULL, root_volume, NULL, 0); 700 dundomap->first_offset = cundomap->first_offset; 701 dundomap->next_offset = save_undo_next_offset; 702 hammer_crc_set_blockmap(dundomap); 703 hammer_modify_volume_done(root_volume); 704 } 705 706 /* 707 * vol0_next_tid is used for TID selection and is updated without 708 * an UNDO so we do not reuse a TID that may have been rolled-back. 709 * 710 * vol0_last_tid is the highest fully-synchronized TID. It is 711 * set-up when the UNDO fifo is fully synced, later on (not here). 712 * 713 * The root volume can be open for modification by other threads 714 * generating UNDO or REDO records. For example, reblocking, 715 * pruning, REDO mode fast-fsyncs, so the write interlock is 716 * mandatory. 717 */ 718 if (root_volume->io.modified) { 719 hammer_modify_volume(NULL, root_volume, NULL, 0); 720 if (root_volume->ondisk->vol0_next_tid < trans->tid) 721 root_volume->ondisk->vol0_next_tid = trans->tid; 722 hammer_crc_set_volume(root_volume->ondisk); 723 hammer_modify_volume_done(root_volume); 724 hammer_io_write_interlock(&root_volume->io); 725 hammer_io_flush(&root_volume->io, 0); 726 hammer_io_done_interlock(&root_volume->io); 727 } 728 729 /* 730 * Wait for I/Os to complete. 731 * 732 * For HAMMER VERSION 4+ filesystems we do not have to wait for 733 * the I/O to complete as the new UNDO FIFO entries are recognized 734 * even without the volume header update. This allows the volume 735 * header to flushed along with meta-data, significantly reducing 736 * flush overheads. 737 */ 738 hammer_flusher_clean_loose_ios(hmp); 739 if (hmp->version < HAMMER_VOL_VERSION_FOUR) 740 hammer_io_wait_all(hmp, "hmrfl3", 1); 741 742 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) 743 goto failed; 744 745 /* 746 * Flush meta-data. The meta-data will be undone if we crash 747 * so we can safely flush it asynchronously. There is no need 748 * to wait for I/O to complete (or issue a synchronous disk flush). 749 * 750 * In fact, even if we did wait the meta-data will still be undone 751 * by a crash up until the next flush cycle due to the first_offset 752 * in the volume header for the UNDO FIFO not being adjusted until 753 * the following flush cycle. 754 * 755 * No io interlock is needed, bioops callbacks will not mess with 756 * meta data buffers. 757 */ 758 count = 0; 759 while ((io = TAILQ_FIRST(&hmp->meta_list)) != NULL) { 760 if (io->ioerror) 761 break; 762 KKASSERT(io->modify_refs == 0); 763 hammer_ref(&io->lock); 764 KKASSERT(io->type != HAMMER_STRUCTURE_VOLUME); 765 hammer_io_flush(io, 0); 766 hammer_rel_buffer((hammer_buffer_t)io, 0); 767 hammer_io_limit_backlog(hmp); 768 ++count; 769 } 770 771 /* 772 * If this is the final finalization for the flush group set 773 * up for the next sequence by setting a new first_offset in 774 * our cached blockmap and clearing the undo history. 775 * 776 * Even though we have updated our cached first_offset, the on-disk 777 * first_offset still governs available-undo-space calculations. 778 * 779 * We synchronize to save_undo_next_offset rather than 780 * cundomap->next_offset because that is what we flushed out 781 * above. 782 * 783 * NOTE! UNDOs can only be added with the sync_lock held 784 * so we can clear the undo history without racing. 785 * REDOs can be added at any time which is why we 786 * have to be careful and use save_undo_next_offset 787 * when setting the new first_offset. 788 */ 789 if (final) { 790 cundomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX]; 791 if (cundomap->first_offset != save_undo_next_offset) { 792 cundomap->first_offset = save_undo_next_offset; 793 hmp->hflags |= HMNT_UNDO_DIRTY; 794 } else if (cundomap->first_offset != cundomap->next_offset) { 795 hmp->hflags |= HMNT_UNDO_DIRTY; 796 } else { 797 hmp->hflags &= ~HMNT_UNDO_DIRTY; 798 } 799 hammer_clear_undo_history(hmp); 800 801 /* 802 * Flush tid sequencing. flush_tid1 is fully synchronized, 803 * meaning a crash will not roll it back. flush_tid2 has 804 * been written out asynchronously and a crash will roll 805 * it back. flush_tid1 is used for all mirroring masters. 806 */ 807 if (hmp->flush_tid1 != hmp->flush_tid2) { 808 hmp->flush_tid1 = hmp->flush_tid2; 809 wakeup(&hmp->flush_tid1); 810 } 811 hmp->flush_tid2 = trans->tid; 812 813 /* 814 * Clear the REDO SYNC flag. This flag is used to ensure 815 * that the recovery span in the UNDO/REDO FIFO contains 816 * at least one REDO SYNC record. 817 */ 818 hmp->flags &= ~HAMMER_MOUNT_REDO_SYNC; 819 } 820 821 /* 822 * Cleanup. Report any critical errors. 823 */ 824 failed: 825 hammer_sync_unlock(trans); 826 827 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) { 828 kprintf("HAMMER(%s): Critical write error during flush, " 829 "refusing to sync UNDO FIFO\n", 830 root_volume->ondisk->vol_name); 831 } 832 833 done: 834 hammer_unlock(&hmp->flusher.finalize_lock); 835 836 if (--hmp->flusher.finalize_want == 0) 837 wakeup(&hmp->flusher.finalize_want); 838 hammer_stats_commits += final; 839 } 840 841 /* 842 * Flush UNDOs. 843 */ 844 void 845 hammer_flusher_flush_undos(hammer_mount_t hmp, int mode) 846 { 847 hammer_io_t io; 848 int count; 849 850 count = 0; 851 while ((io = TAILQ_FIRST(&hmp->undo_list)) != NULL) { 852 if (io->ioerror) 853 break; 854 hammer_ref(&io->lock); 855 KKASSERT(io->type != HAMMER_STRUCTURE_VOLUME); 856 hammer_io_write_interlock(io); 857 hammer_io_flush(io, hammer_undo_reclaim(io)); 858 hammer_io_done_interlock(io); 859 hammer_rel_buffer((hammer_buffer_t)io, 0); 860 hammer_io_limit_backlog(hmp); 861 ++count; 862 } 863 hammer_flusher_clean_loose_ios(hmp); 864 if (mode == HAMMER_FLUSH_UNDOS_FORCED || 865 (mode == HAMMER_FLUSH_UNDOS_AUTO && count)) { 866 hammer_io_wait_all(hmp, "hmrfl1", 1); 867 } else { 868 hammer_io_wait_all(hmp, "hmrfl2", 0); 869 } 870 } 871 872 /* 873 * Return non-zero if too many dirty meta-data buffers have built up. 874 * 875 * Since we cannot allow such buffers to flush until we have dealt with 876 * the UNDOs, we risk deadlocking the kernel's buffer cache. 877 */ 878 int 879 hammer_flusher_meta_limit(hammer_mount_t hmp) 880 { 881 if (hmp->locked_dirty_space + hmp->io_running_space > 882 hammer_limit_dirtybufspace) { 883 return(1); 884 } 885 return(0); 886 } 887 888 /* 889 * Return non-zero if too many dirty meta-data buffers have built up. 890 * 891 * This version is used by background operations (mirror, prune, reblock) 892 * to leave room for foreground operations. 893 */ 894 int 895 hammer_flusher_meta_halflimit(hammer_mount_t hmp) 896 { 897 if (hmp->locked_dirty_space + hmp->io_running_space > 898 hammer_limit_dirtybufspace / 2) { 899 return(1); 900 } 901 return(0); 902 } 903 904 /* 905 * Return non-zero if the flusher still has something to flush. 906 */ 907 int 908 hammer_flusher_haswork(hammer_mount_t hmp) 909 { 910 if (hmp->ronly) 911 return(0); 912 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) 913 return(0); 914 if (TAILQ_FIRST(&hmp->flush_group_list) || /* dirty inodes */ 915 TAILQ_FIRST(&hmp->volu_list) || /* dirty buffers */ 916 TAILQ_FIRST(&hmp->undo_list) || 917 TAILQ_FIRST(&hmp->data_list) || 918 TAILQ_FIRST(&hmp->meta_list) || 919 (hmp->hflags & HMNT_UNDO_DIRTY) /* UNDO FIFO sync */ 920 ) { 921 return(1); 922 } 923 return(0); 924 } 925 926