dm-raid1.c revision 1f965b19437017cea6d3f3f46acdc5acae5fd011
1/* 2 * Copyright (C) 2003 Sistina Software Limited. 3 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved. 4 * 5 * This file is released under the GPL. 6 */ 7 8#include "dm-bio-list.h" 9#include "dm-bio-record.h" 10 11#include <linux/init.h> 12#include <linux/mempool.h> 13#include <linux/module.h> 14#include <linux/pagemap.h> 15#include <linux/slab.h> 16#include <linux/workqueue.h> 17#include <linux/device-mapper.h> 18#include <linux/dm-io.h> 19#include <linux/dm-dirty-log.h> 20#include <linux/dm-kcopyd.h> 21#include <linux/dm-region-hash.h> 22 23#define DM_MSG_PREFIX "raid1" 24 25#define MAX_RECOVERY 1 /* Maximum number of regions recovered in parallel. */ 26#define DM_IO_PAGES 64 27#define DM_KCOPYD_PAGES 64 28 29#define DM_RAID1_HANDLE_ERRORS 0x01 30#define errors_handled(p) ((p)->features & DM_RAID1_HANDLE_ERRORS) 31 32static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped); 33 34/*----------------------------------------------------------------- 35 * Mirror set structures. 36 *---------------------------------------------------------------*/ 37enum dm_raid1_error { 38 DM_RAID1_WRITE_ERROR, 39 DM_RAID1_SYNC_ERROR, 40 DM_RAID1_READ_ERROR 41}; 42 43struct mirror { 44 struct mirror_set *ms; 45 atomic_t error_count; 46 unsigned long error_type; 47 struct dm_dev *dev; 48 sector_t offset; 49}; 50 51struct mirror_set { 52 struct dm_target *ti; 53 struct list_head list; 54 55 uint64_t features; 56 57 spinlock_t lock; /* protects the lists */ 58 struct bio_list reads; 59 struct bio_list writes; 60 struct bio_list failures; 61 62 struct dm_region_hash *rh; 63 struct dm_kcopyd_client *kcopyd_client; 64 struct dm_io_client *io_client; 65 mempool_t *read_record_pool; 66 67 /* recovery */ 68 region_t nr_regions; 69 int in_sync; 70 int log_failure; 71 atomic_t suspend; 72 73 atomic_t default_mirror; /* Default mirror */ 74 75 struct workqueue_struct *kmirrord_wq; 76 struct work_struct kmirrord_work; 77 struct timer_list timer; 78 unsigned long timer_pending; 79 80 struct work_struct trigger_event; 81 82 unsigned nr_mirrors; 83 struct mirror mirror[0]; 84}; 85 86static void wakeup_mirrord(void *context) 87{ 88 struct mirror_set *ms = context; 89 90 queue_work(ms->kmirrord_wq, &ms->kmirrord_work); 91} 92 93static void delayed_wake_fn(unsigned long data) 94{ 95 struct mirror_set *ms = (struct mirror_set *) data; 96 97 clear_bit(0, &ms->timer_pending); 98 wakeup_mirrord(ms); 99} 100 101static void delayed_wake(struct mirror_set *ms) 102{ 103 if (test_and_set_bit(0, &ms->timer_pending)) 104 return; 105 106 ms->timer.expires = jiffies + HZ / 5; 107 ms->timer.data = (unsigned long) ms; 108 ms->timer.function = delayed_wake_fn; 109 add_timer(&ms->timer); 110} 111 112static void wakeup_all_recovery_waiters(void *context) 113{ 114 wake_up_all(&_kmirrord_recovery_stopped); 115} 116 117static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw) 118{ 119 unsigned long flags; 120 int should_wake = 0; 121 struct bio_list *bl; 122 123 bl = (rw == WRITE) ? &ms->writes : &ms->reads; 124 spin_lock_irqsave(&ms->lock, flags); 125 should_wake = !(bl->head); 126 bio_list_add(bl, bio); 127 spin_unlock_irqrestore(&ms->lock, flags); 128 129 if (should_wake) 130 wakeup_mirrord(ms); 131} 132 133static void dispatch_bios(void *context, struct bio_list *bio_list) 134{ 135 struct mirror_set *ms = context; 136 struct bio *bio; 137 138 while ((bio = bio_list_pop(bio_list))) 139 queue_bio(ms, bio, WRITE); 140} 141 142#define MIN_READ_RECORDS 20 143struct dm_raid1_read_record { 144 struct mirror *m; 145 struct dm_bio_details details; 146}; 147 148/* 149 * Every mirror should look like this one. 150 */ 151#define DEFAULT_MIRROR 0 152 153/* 154 * This is yucky. We squirrel the mirror struct away inside 155 * bi_next for read/write buffers. This is safe since the bh 156 * doesn't get submitted to the lower levels of block layer. 157 */ 158static struct mirror *bio_get_m(struct bio *bio) 159{ 160 return (struct mirror *) bio->bi_next; 161} 162 163static void bio_set_m(struct bio *bio, struct mirror *m) 164{ 165 bio->bi_next = (struct bio *) m; 166} 167 168static struct mirror *get_default_mirror(struct mirror_set *ms) 169{ 170 return &ms->mirror[atomic_read(&ms->default_mirror)]; 171} 172 173static void set_default_mirror(struct mirror *m) 174{ 175 struct mirror_set *ms = m->ms; 176 struct mirror *m0 = &(ms->mirror[0]); 177 178 atomic_set(&ms->default_mirror, m - m0); 179} 180 181/* fail_mirror 182 * @m: mirror device to fail 183 * @error_type: one of the enum's, DM_RAID1_*_ERROR 184 * 185 * If errors are being handled, record the type of 186 * error encountered for this device. If this type 187 * of error has already been recorded, we can return; 188 * otherwise, we must signal userspace by triggering 189 * an event. Additionally, if the device is the 190 * primary device, we must choose a new primary, but 191 * only if the mirror is in-sync. 192 * 193 * This function must not block. 194 */ 195static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type) 196{ 197 struct mirror_set *ms = m->ms; 198 struct mirror *new; 199 200 if (!errors_handled(ms)) 201 return; 202 203 /* 204 * error_count is used for nothing more than a 205 * simple way to tell if a device has encountered 206 * errors. 207 */ 208 atomic_inc(&m->error_count); 209 210 if (test_and_set_bit(error_type, &m->error_type)) 211 return; 212 213 if (m != get_default_mirror(ms)) 214 goto out; 215 216 if (!ms->in_sync) { 217 /* 218 * Better to issue requests to same failing device 219 * than to risk returning corrupt data. 220 */ 221 DMERR("Primary mirror (%s) failed while out-of-sync: " 222 "Reads may fail.", m->dev->name); 223 goto out; 224 } 225 226 for (new = ms->mirror; new < ms->mirror + ms->nr_mirrors; new++) 227 if (!atomic_read(&new->error_count)) { 228 set_default_mirror(new); 229 break; 230 } 231 232 if (unlikely(new == ms->mirror + ms->nr_mirrors)) 233 DMWARN("All sides of mirror have failed."); 234 235out: 236 schedule_work(&ms->trigger_event); 237} 238 239/*----------------------------------------------------------------- 240 * Recovery. 241 * 242 * When a mirror is first activated we may find that some regions 243 * are in the no-sync state. We have to recover these by 244 * recopying from the default mirror to all the others. 245 *---------------------------------------------------------------*/ 246static void recovery_complete(int read_err, unsigned long write_err, 247 void *context) 248{ 249 struct dm_region *reg = context; 250 struct mirror_set *ms = dm_rh_region_context(reg); 251 int m, bit = 0; 252 253 if (read_err) { 254 /* Read error means the failure of default mirror. */ 255 DMERR_LIMIT("Unable to read primary mirror during recovery"); 256 fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR); 257 } 258 259 if (write_err) { 260 DMERR_LIMIT("Write error during recovery (error = 0x%lx)", 261 write_err); 262 /* 263 * Bits correspond to devices (excluding default mirror). 264 * The default mirror cannot change during recovery. 265 */ 266 for (m = 0; m < ms->nr_mirrors; m++) { 267 if (&ms->mirror[m] == get_default_mirror(ms)) 268 continue; 269 if (test_bit(bit, &write_err)) 270 fail_mirror(ms->mirror + m, 271 DM_RAID1_SYNC_ERROR); 272 bit++; 273 } 274 } 275 276 dm_rh_recovery_end(reg, !(read_err || write_err)); 277} 278 279static int recover(struct mirror_set *ms, struct dm_region *reg) 280{ 281 int r; 282 unsigned i; 283 struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest; 284 struct mirror *m; 285 unsigned long flags = 0; 286 region_t key = dm_rh_get_region_key(reg); 287 sector_t region_size = dm_rh_get_region_size(ms->rh); 288 289 /* fill in the source */ 290 m = get_default_mirror(ms); 291 from.bdev = m->dev->bdev; 292 from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key); 293 if (key == (ms->nr_regions - 1)) { 294 /* 295 * The final region may be smaller than 296 * region_size. 297 */ 298 from.count = ms->ti->len & (region_size - 1); 299 if (!from.count) 300 from.count = region_size; 301 } else 302 from.count = region_size; 303 304 /* fill in the destinations */ 305 for (i = 0, dest = to; i < ms->nr_mirrors; i++) { 306 if (&ms->mirror[i] == get_default_mirror(ms)) 307 continue; 308 309 m = ms->mirror + i; 310 dest->bdev = m->dev->bdev; 311 dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key); 312 dest->count = from.count; 313 dest++; 314 } 315 316 /* hand to kcopyd */ 317 if (!errors_handled(ms)) 318 set_bit(DM_KCOPYD_IGNORE_ERROR, &flags); 319 320 r = dm_kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to, 321 flags, recovery_complete, reg); 322 323 return r; 324} 325 326static void do_recovery(struct mirror_set *ms) 327{ 328 struct dm_region *reg; 329 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 330 int r; 331 332 /* 333 * Start quiescing some regions. 334 */ 335 dm_rh_recovery_prepare(ms->rh); 336 337 /* 338 * Copy any already quiesced regions. 339 */ 340 while ((reg = dm_rh_recovery_start(ms->rh))) { 341 r = recover(ms, reg); 342 if (r) 343 dm_rh_recovery_end(reg, 0); 344 } 345 346 /* 347 * Update the in sync flag. 348 */ 349 if (!ms->in_sync && 350 (log->type->get_sync_count(log) == ms->nr_regions)) { 351 /* the sync is complete */ 352 dm_table_event(ms->ti->table); 353 ms->in_sync = 1; 354 } 355} 356 357/*----------------------------------------------------------------- 358 * Reads 359 *---------------------------------------------------------------*/ 360static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector) 361{ 362 struct mirror *m = get_default_mirror(ms); 363 364 do { 365 if (likely(!atomic_read(&m->error_count))) 366 return m; 367 368 if (m-- == ms->mirror) 369 m += ms->nr_mirrors; 370 } while (m != get_default_mirror(ms)); 371 372 return NULL; 373} 374 375static int default_ok(struct mirror *m) 376{ 377 struct mirror *default_mirror = get_default_mirror(m->ms); 378 379 return !atomic_read(&default_mirror->error_count); 380} 381 382static int mirror_available(struct mirror_set *ms, struct bio *bio) 383{ 384 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 385 region_t region = dm_rh_bio_to_region(ms->rh, bio); 386 387 if (log->type->in_sync(log, region, 0)) 388 return choose_mirror(ms, bio->bi_sector) ? 1 : 0; 389 390 return 0; 391} 392 393/* 394 * remap a buffer to a particular mirror. 395 */ 396static sector_t map_sector(struct mirror *m, struct bio *bio) 397{ 398 return m->offset + (bio->bi_sector - m->ms->ti->begin); 399} 400 401static void map_bio(struct mirror *m, struct bio *bio) 402{ 403 bio->bi_bdev = m->dev->bdev; 404 bio->bi_sector = map_sector(m, bio); 405} 406 407static void map_region(struct dm_io_region *io, struct mirror *m, 408 struct bio *bio) 409{ 410 io->bdev = m->dev->bdev; 411 io->sector = map_sector(m, bio); 412 io->count = bio->bi_size >> 9; 413} 414 415/*----------------------------------------------------------------- 416 * Reads 417 *---------------------------------------------------------------*/ 418static void read_callback(unsigned long error, void *context) 419{ 420 struct bio *bio = context; 421 struct mirror *m; 422 423 m = bio_get_m(bio); 424 bio_set_m(bio, NULL); 425 426 if (likely(!error)) { 427 bio_endio(bio, 0); 428 return; 429 } 430 431 fail_mirror(m, DM_RAID1_READ_ERROR); 432 433 if (likely(default_ok(m)) || mirror_available(m->ms, bio)) { 434 DMWARN_LIMIT("Read failure on mirror device %s. " 435 "Trying alternative device.", 436 m->dev->name); 437 queue_bio(m->ms, bio, bio_rw(bio)); 438 return; 439 } 440 441 DMERR_LIMIT("Read failure on mirror device %s. Failing I/O.", 442 m->dev->name); 443 bio_endio(bio, -EIO); 444} 445 446/* Asynchronous read. */ 447static void read_async_bio(struct mirror *m, struct bio *bio) 448{ 449 struct dm_io_region io; 450 struct dm_io_request io_req = { 451 .bi_rw = READ, 452 .mem.type = DM_IO_BVEC, 453 .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx, 454 .notify.fn = read_callback, 455 .notify.context = bio, 456 .client = m->ms->io_client, 457 }; 458 459 map_region(&io, m, bio); 460 bio_set_m(bio, m); 461 BUG_ON(dm_io(&io_req, 1, &io, NULL)); 462} 463 464static inline int region_in_sync(struct mirror_set *ms, region_t region, 465 int may_block) 466{ 467 int state = dm_rh_get_state(ms->rh, region, may_block); 468 return state == DM_RH_CLEAN || state == DM_RH_DIRTY; 469} 470 471static void do_reads(struct mirror_set *ms, struct bio_list *reads) 472{ 473 region_t region; 474 struct bio *bio; 475 struct mirror *m; 476 477 while ((bio = bio_list_pop(reads))) { 478 region = dm_rh_bio_to_region(ms->rh, bio); 479 m = get_default_mirror(ms); 480 481 /* 482 * We can only read balance if the region is in sync. 483 */ 484 if (likely(region_in_sync(ms, region, 1))) 485 m = choose_mirror(ms, bio->bi_sector); 486 else if (m && atomic_read(&m->error_count)) 487 m = NULL; 488 489 if (likely(m)) 490 read_async_bio(m, bio); 491 else 492 bio_endio(bio, -EIO); 493 } 494} 495 496/*----------------------------------------------------------------- 497 * Writes. 498 * 499 * We do different things with the write io depending on the 500 * state of the region that it's in: 501 * 502 * SYNC: increment pending, use kcopyd to write to *all* mirrors 503 * RECOVERING: delay the io until recovery completes 504 * NOSYNC: increment pending, just write to the default mirror 505 *---------------------------------------------------------------*/ 506 507 508static void write_callback(unsigned long error, void *context) 509{ 510 unsigned i, ret = 0; 511 struct bio *bio = (struct bio *) context; 512 struct mirror_set *ms; 513 int uptodate = 0; 514 int should_wake = 0; 515 unsigned long flags; 516 517 ms = bio_get_m(bio)->ms; 518 bio_set_m(bio, NULL); 519 520 /* 521 * NOTE: We don't decrement the pending count here, 522 * instead it is done by the targets endio function. 523 * This way we handle both writes to SYNC and NOSYNC 524 * regions with the same code. 525 */ 526 if (likely(!error)) 527 goto out; 528 529 for (i = 0; i < ms->nr_mirrors; i++) 530 if (test_bit(i, &error)) 531 fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR); 532 else 533 uptodate = 1; 534 535 if (unlikely(!uptodate)) { 536 DMERR("All replicated volumes dead, failing I/O"); 537 /* None of the writes succeeded, fail the I/O. */ 538 ret = -EIO; 539 } else if (errors_handled(ms)) { 540 /* 541 * Need to raise event. Since raising 542 * events can block, we need to do it in 543 * the main thread. 544 */ 545 spin_lock_irqsave(&ms->lock, flags); 546 if (!ms->failures.head) 547 should_wake = 1; 548 bio_list_add(&ms->failures, bio); 549 spin_unlock_irqrestore(&ms->lock, flags); 550 if (should_wake) 551 wakeup_mirrord(ms); 552 return; 553 } 554out: 555 bio_endio(bio, ret); 556} 557 558static void do_write(struct mirror_set *ms, struct bio *bio) 559{ 560 unsigned int i; 561 struct dm_io_region io[ms->nr_mirrors], *dest = io; 562 struct mirror *m; 563 struct dm_io_request io_req = { 564 .bi_rw = WRITE, 565 .mem.type = DM_IO_BVEC, 566 .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx, 567 .notify.fn = write_callback, 568 .notify.context = bio, 569 .client = ms->io_client, 570 }; 571 572 for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) 573 map_region(dest++, m, bio); 574 575 /* 576 * Use default mirror because we only need it to retrieve the reference 577 * to the mirror set in write_callback(). 578 */ 579 bio_set_m(bio, get_default_mirror(ms)); 580 581 BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL)); 582} 583 584static void do_writes(struct mirror_set *ms, struct bio_list *writes) 585{ 586 int state; 587 struct bio *bio; 588 struct bio_list sync, nosync, recover, *this_list = NULL; 589 590 if (!writes->head) 591 return; 592 593 /* 594 * Classify each write. 595 */ 596 bio_list_init(&sync); 597 bio_list_init(&nosync); 598 bio_list_init(&recover); 599 600 while ((bio = bio_list_pop(writes))) { 601 state = dm_rh_get_state(ms->rh, 602 dm_rh_bio_to_region(ms->rh, bio), 1); 603 switch (state) { 604 case DM_RH_CLEAN: 605 case DM_RH_DIRTY: 606 this_list = &sync; 607 break; 608 609 case DM_RH_NOSYNC: 610 this_list = &nosync; 611 break; 612 613 case DM_RH_RECOVERING: 614 this_list = &recover; 615 break; 616 } 617 618 bio_list_add(this_list, bio); 619 } 620 621 /* 622 * Increment the pending counts for any regions that will 623 * be written to (writes to recover regions are going to 624 * be delayed). 625 */ 626 dm_rh_inc_pending(ms->rh, &sync); 627 dm_rh_inc_pending(ms->rh, &nosync); 628 ms->log_failure = dm_rh_flush(ms->rh) ? 1 : 0; 629 630 /* 631 * Dispatch io. 632 */ 633 if (unlikely(ms->log_failure)) { 634 spin_lock_irq(&ms->lock); 635 bio_list_merge(&ms->failures, &sync); 636 spin_unlock_irq(&ms->lock); 637 wakeup_mirrord(ms); 638 } else 639 while ((bio = bio_list_pop(&sync))) 640 do_write(ms, bio); 641 642 while ((bio = bio_list_pop(&recover))) 643 dm_rh_delay(ms->rh, bio); 644 645 while ((bio = bio_list_pop(&nosync))) { 646 map_bio(get_default_mirror(ms), bio); 647 generic_make_request(bio); 648 } 649} 650 651static void do_failures(struct mirror_set *ms, struct bio_list *failures) 652{ 653 struct bio *bio; 654 655 if (!failures->head) 656 return; 657 658 if (!ms->log_failure) { 659 while ((bio = bio_list_pop(failures))) 660 ms->in_sync = 0; 661 dm_rh_mark_nosync(ms->rh, bio, bio->bi_size, 0); 662 return; 663 } 664 665 /* 666 * If the log has failed, unattempted writes are being 667 * put on the failures list. We can't issue those writes 668 * until a log has been marked, so we must store them. 669 * 670 * If a 'noflush' suspend is in progress, we can requeue 671 * the I/O's to the core. This give userspace a chance 672 * to reconfigure the mirror, at which point the core 673 * will reissue the writes. If the 'noflush' flag is 674 * not set, we have no choice but to return errors. 675 * 676 * Some writes on the failures list may have been 677 * submitted before the log failure and represent a 678 * failure to write to one of the devices. It is ok 679 * for us to treat them the same and requeue them 680 * as well. 681 */ 682 if (dm_noflush_suspending(ms->ti)) { 683 while ((bio = bio_list_pop(failures))) 684 bio_endio(bio, DM_ENDIO_REQUEUE); 685 return; 686 } 687 688 if (atomic_read(&ms->suspend)) { 689 while ((bio = bio_list_pop(failures))) 690 bio_endio(bio, -EIO); 691 return; 692 } 693 694 spin_lock_irq(&ms->lock); 695 bio_list_merge(&ms->failures, failures); 696 spin_unlock_irq(&ms->lock); 697 698 delayed_wake(ms); 699} 700 701static void trigger_event(struct work_struct *work) 702{ 703 struct mirror_set *ms = 704 container_of(work, struct mirror_set, trigger_event); 705 706 dm_table_event(ms->ti->table); 707} 708 709/*----------------------------------------------------------------- 710 * kmirrord 711 *---------------------------------------------------------------*/ 712static void do_mirror(struct work_struct *work) 713{ 714 struct mirror_set *ms = container_of(work, struct mirror_set, 715 kmirrord_work); 716 struct bio_list reads, writes, failures; 717 unsigned long flags; 718 719 spin_lock_irqsave(&ms->lock, flags); 720 reads = ms->reads; 721 writes = ms->writes; 722 failures = ms->failures; 723 bio_list_init(&ms->reads); 724 bio_list_init(&ms->writes); 725 bio_list_init(&ms->failures); 726 spin_unlock_irqrestore(&ms->lock, flags); 727 728 dm_rh_update_states(ms->rh, errors_handled(ms)); 729 do_recovery(ms); 730 do_reads(ms, &reads); 731 do_writes(ms, &writes); 732 do_failures(ms, &failures); 733 734 dm_table_unplug_all(ms->ti->table); 735} 736 737/*----------------------------------------------------------------- 738 * Target functions 739 *---------------------------------------------------------------*/ 740static struct mirror_set *alloc_context(unsigned int nr_mirrors, 741 uint32_t region_size, 742 struct dm_target *ti, 743 struct dm_dirty_log *dl) 744{ 745 size_t len; 746 struct mirror_set *ms = NULL; 747 748 len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors); 749 750 ms = kzalloc(len, GFP_KERNEL); 751 if (!ms) { 752 ti->error = "Cannot allocate mirror context"; 753 return NULL; 754 } 755 756 spin_lock_init(&ms->lock); 757 758 ms->ti = ti; 759 ms->nr_mirrors = nr_mirrors; 760 ms->nr_regions = dm_sector_div_up(ti->len, region_size); 761 ms->in_sync = 0; 762 ms->log_failure = 0; 763 atomic_set(&ms->suspend, 0); 764 atomic_set(&ms->default_mirror, DEFAULT_MIRROR); 765 766 len = sizeof(struct dm_raid1_read_record); 767 ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS, 768 len); 769 if (!ms->read_record_pool) { 770 ti->error = "Error creating mirror read_record_pool"; 771 kfree(ms); 772 return NULL; 773 } 774 775 ms->io_client = dm_io_client_create(DM_IO_PAGES); 776 if (IS_ERR(ms->io_client)) { 777 ti->error = "Error creating dm_io client"; 778 mempool_destroy(ms->read_record_pool); 779 kfree(ms); 780 return NULL; 781 } 782 783 ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord, 784 wakeup_all_recovery_waiters, 785 ms->ti->begin, MAX_RECOVERY, 786 dl, region_size, ms->nr_regions); 787 if (IS_ERR(ms->rh)) { 788 ti->error = "Error creating dirty region hash"; 789 dm_io_client_destroy(ms->io_client); 790 mempool_destroy(ms->read_record_pool); 791 kfree(ms); 792 return NULL; 793 } 794 795 return ms; 796} 797 798static void free_context(struct mirror_set *ms, struct dm_target *ti, 799 unsigned int m) 800{ 801 while (m--) 802 dm_put_device(ti, ms->mirror[m].dev); 803 804 dm_io_client_destroy(ms->io_client); 805 dm_region_hash_destroy(ms->rh); 806 mempool_destroy(ms->read_record_pool); 807 kfree(ms); 808} 809 810static inline int _check_region_size(struct dm_target *ti, uint32_t size) 811{ 812 return !(size % (PAGE_SIZE >> 9) || !is_power_of_2(size) || 813 size > ti->len); 814} 815 816static int get_mirror(struct mirror_set *ms, struct dm_target *ti, 817 unsigned int mirror, char **argv) 818{ 819 unsigned long long offset; 820 821 if (sscanf(argv[1], "%llu", &offset) != 1) { 822 ti->error = "Invalid offset"; 823 return -EINVAL; 824 } 825 826 if (dm_get_device(ti, argv[0], offset, ti->len, 827 dm_table_get_mode(ti->table), 828 &ms->mirror[mirror].dev)) { 829 ti->error = "Device lookup failure"; 830 return -ENXIO; 831 } 832 833 ms->mirror[mirror].ms = ms; 834 atomic_set(&(ms->mirror[mirror].error_count), 0); 835 ms->mirror[mirror].error_type = 0; 836 ms->mirror[mirror].offset = offset; 837 838 return 0; 839} 840 841/* 842 * Create dirty log: log_type #log_params <log_params> 843 */ 844static struct dm_dirty_log *create_dirty_log(struct dm_target *ti, 845 unsigned argc, char **argv, 846 unsigned *args_used) 847{ 848 unsigned param_count; 849 struct dm_dirty_log *dl; 850 851 if (argc < 2) { 852 ti->error = "Insufficient mirror log arguments"; 853 return NULL; 854 } 855 856 if (sscanf(argv[1], "%u", ¶m_count) != 1) { 857 ti->error = "Invalid mirror log argument count"; 858 return NULL; 859 } 860 861 *args_used = 2 + param_count; 862 863 if (argc < *args_used) { 864 ti->error = "Insufficient mirror log arguments"; 865 return NULL; 866 } 867 868 dl = dm_dirty_log_create(argv[0], ti, param_count, argv + 2); 869 if (!dl) { 870 ti->error = "Error creating mirror dirty log"; 871 return NULL; 872 } 873 874 if (!_check_region_size(ti, dl->type->get_region_size(dl))) { 875 ti->error = "Invalid region size"; 876 dm_dirty_log_destroy(dl); 877 return NULL; 878 } 879 880 return dl; 881} 882 883static int parse_features(struct mirror_set *ms, unsigned argc, char **argv, 884 unsigned *args_used) 885{ 886 unsigned num_features; 887 struct dm_target *ti = ms->ti; 888 889 *args_used = 0; 890 891 if (!argc) 892 return 0; 893 894 if (sscanf(argv[0], "%u", &num_features) != 1) { 895 ti->error = "Invalid number of features"; 896 return -EINVAL; 897 } 898 899 argc--; 900 argv++; 901 (*args_used)++; 902 903 if (num_features > argc) { 904 ti->error = "Not enough arguments to support feature count"; 905 return -EINVAL; 906 } 907 908 if (!strcmp("handle_errors", argv[0])) 909 ms->features |= DM_RAID1_HANDLE_ERRORS; 910 else { 911 ti->error = "Unrecognised feature requested"; 912 return -EINVAL; 913 } 914 915 (*args_used)++; 916 917 return 0; 918} 919 920/* 921 * Construct a mirror mapping: 922 * 923 * log_type #log_params <log_params> 924 * #mirrors [mirror_path offset]{2,} 925 * [#features <features>] 926 * 927 * log_type is "core" or "disk" 928 * #log_params is between 1 and 3 929 * 930 * If present, features must be "handle_errors". 931 */ 932static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv) 933{ 934 int r; 935 unsigned int nr_mirrors, m, args_used; 936 struct mirror_set *ms; 937 struct dm_dirty_log *dl; 938 939 dl = create_dirty_log(ti, argc, argv, &args_used); 940 if (!dl) 941 return -EINVAL; 942 943 argv += args_used; 944 argc -= args_used; 945 946 if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 || 947 nr_mirrors < 2 || nr_mirrors > DM_KCOPYD_MAX_REGIONS + 1) { 948 ti->error = "Invalid number of mirrors"; 949 dm_dirty_log_destroy(dl); 950 return -EINVAL; 951 } 952 953 argv++, argc--; 954 955 if (argc < nr_mirrors * 2) { 956 ti->error = "Too few mirror arguments"; 957 dm_dirty_log_destroy(dl); 958 return -EINVAL; 959 } 960 961 ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl); 962 if (!ms) { 963 dm_dirty_log_destroy(dl); 964 return -ENOMEM; 965 } 966 967 /* Get the mirror parameter sets */ 968 for (m = 0; m < nr_mirrors; m++) { 969 r = get_mirror(ms, ti, m, argv); 970 if (r) { 971 free_context(ms, ti, m); 972 return r; 973 } 974 argv += 2; 975 argc -= 2; 976 } 977 978 ti->private = ms; 979 ti->split_io = dm_rh_get_region_size(ms->rh); 980 981 ms->kmirrord_wq = create_singlethread_workqueue("kmirrord"); 982 if (!ms->kmirrord_wq) { 983 DMERR("couldn't start kmirrord"); 984 r = -ENOMEM; 985 goto err_free_context; 986 } 987 INIT_WORK(&ms->kmirrord_work, do_mirror); 988 init_timer(&ms->timer); 989 ms->timer_pending = 0; 990 INIT_WORK(&ms->trigger_event, trigger_event); 991 992 r = parse_features(ms, argc, argv, &args_used); 993 if (r) 994 goto err_destroy_wq; 995 996 argv += args_used; 997 argc -= args_used; 998 999 /* 1000 * Any read-balancing addition depends on the 1001 * DM_RAID1_HANDLE_ERRORS flag being present. 1002 * This is because the decision to balance depends 1003 * on the sync state of a region. If the above 1004 * flag is not present, we ignore errors; and 1005 * the sync state may be inaccurate. 1006 */ 1007 1008 if (argc) { 1009 ti->error = "Too many mirror arguments"; 1010 r = -EINVAL; 1011 goto err_destroy_wq; 1012 } 1013 1014 r = dm_kcopyd_client_create(DM_KCOPYD_PAGES, &ms->kcopyd_client); 1015 if (r) 1016 goto err_destroy_wq; 1017 1018 wakeup_mirrord(ms); 1019 return 0; 1020 1021err_destroy_wq: 1022 destroy_workqueue(ms->kmirrord_wq); 1023err_free_context: 1024 free_context(ms, ti, ms->nr_mirrors); 1025 return r; 1026} 1027 1028static void mirror_dtr(struct dm_target *ti) 1029{ 1030 struct mirror_set *ms = (struct mirror_set *) ti->private; 1031 1032 del_timer_sync(&ms->timer); 1033 flush_workqueue(ms->kmirrord_wq); 1034 dm_kcopyd_client_destroy(ms->kcopyd_client); 1035 destroy_workqueue(ms->kmirrord_wq); 1036 free_context(ms, ti, ms->nr_mirrors); 1037} 1038 1039/* 1040 * Mirror mapping function 1041 */ 1042static int mirror_map(struct dm_target *ti, struct bio *bio, 1043 union map_info *map_context) 1044{ 1045 int r, rw = bio_rw(bio); 1046 struct mirror *m; 1047 struct mirror_set *ms = ti->private; 1048 struct dm_raid1_read_record *read_record = NULL; 1049 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 1050 1051 if (rw == WRITE) { 1052 /* Save region for mirror_end_io() handler */ 1053 map_context->ll = dm_rh_bio_to_region(ms->rh, bio); 1054 queue_bio(ms, bio, rw); 1055 return DM_MAPIO_SUBMITTED; 1056 } 1057 1058 r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0); 1059 if (r < 0 && r != -EWOULDBLOCK) 1060 return r; 1061 1062 /* 1063 * If region is not in-sync queue the bio. 1064 */ 1065 if (!r || (r == -EWOULDBLOCK)) { 1066 if (rw == READA) 1067 return -EWOULDBLOCK; 1068 1069 queue_bio(ms, bio, rw); 1070 return DM_MAPIO_SUBMITTED; 1071 } 1072 1073 /* 1074 * The region is in-sync and we can perform reads directly. 1075 * Store enough information so we can retry if it fails. 1076 */ 1077 m = choose_mirror(ms, bio->bi_sector); 1078 if (unlikely(!m)) 1079 return -EIO; 1080 1081 read_record = mempool_alloc(ms->read_record_pool, GFP_NOIO); 1082 if (likely(read_record)) { 1083 dm_bio_record(&read_record->details, bio); 1084 map_context->ptr = read_record; 1085 read_record->m = m; 1086 } 1087 1088 map_bio(m, bio); 1089 1090 return DM_MAPIO_REMAPPED; 1091} 1092 1093static int mirror_end_io(struct dm_target *ti, struct bio *bio, 1094 int error, union map_info *map_context) 1095{ 1096 int rw = bio_rw(bio); 1097 struct mirror_set *ms = (struct mirror_set *) ti->private; 1098 struct mirror *m = NULL; 1099 struct dm_bio_details *bd = NULL; 1100 struct dm_raid1_read_record *read_record = map_context->ptr; 1101 1102 /* 1103 * We need to dec pending if this was a write. 1104 */ 1105 if (rw == WRITE) { 1106 dm_rh_dec(ms->rh, map_context->ll); 1107 return error; 1108 } 1109 1110 if (error == -EOPNOTSUPP) 1111 goto out; 1112 1113 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) 1114 goto out; 1115 1116 if (unlikely(error)) { 1117 if (!read_record) { 1118 /* 1119 * There wasn't enough memory to record necessary 1120 * information for a retry or there was no other 1121 * mirror in-sync. 1122 */ 1123 DMERR_LIMIT("Mirror read failed."); 1124 return -EIO; 1125 } 1126 1127 m = read_record->m; 1128 1129 DMERR("Mirror read failed from %s. Trying alternative device.", 1130 m->dev->name); 1131 1132 fail_mirror(m, DM_RAID1_READ_ERROR); 1133 1134 /* 1135 * A failed read is requeued for another attempt using an intact 1136 * mirror. 1137 */ 1138 if (default_ok(m) || mirror_available(ms, bio)) { 1139 bd = &read_record->details; 1140 1141 dm_bio_restore(bd, bio); 1142 mempool_free(read_record, ms->read_record_pool); 1143 map_context->ptr = NULL; 1144 queue_bio(ms, bio, rw); 1145 return 1; 1146 } 1147 DMERR("All replicated volumes dead, failing I/O"); 1148 } 1149 1150out: 1151 if (read_record) { 1152 mempool_free(read_record, ms->read_record_pool); 1153 map_context->ptr = NULL; 1154 } 1155 1156 return error; 1157} 1158 1159static void mirror_presuspend(struct dm_target *ti) 1160{ 1161 struct mirror_set *ms = (struct mirror_set *) ti->private; 1162 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 1163 1164 atomic_set(&ms->suspend, 1); 1165 1166 /* 1167 * We must finish up all the work that we've 1168 * generated (i.e. recovery work). 1169 */ 1170 dm_rh_stop_recovery(ms->rh); 1171 1172 wait_event(_kmirrord_recovery_stopped, 1173 !dm_rh_recovery_in_flight(ms->rh)); 1174 1175 if (log->type->presuspend && log->type->presuspend(log)) 1176 /* FIXME: need better error handling */ 1177 DMWARN("log presuspend failed"); 1178 1179 /* 1180 * Now that recovery is complete/stopped and the 1181 * delayed bios are queued, we need to wait for 1182 * the worker thread to complete. This way, 1183 * we know that all of our I/O has been pushed. 1184 */ 1185 flush_workqueue(ms->kmirrord_wq); 1186} 1187 1188static void mirror_postsuspend(struct dm_target *ti) 1189{ 1190 struct mirror_set *ms = ti->private; 1191 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 1192 1193 if (log->type->postsuspend && log->type->postsuspend(log)) 1194 /* FIXME: need better error handling */ 1195 DMWARN("log postsuspend failed"); 1196} 1197 1198static void mirror_resume(struct dm_target *ti) 1199{ 1200 struct mirror_set *ms = ti->private; 1201 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 1202 1203 atomic_set(&ms->suspend, 0); 1204 if (log->type->resume && log->type->resume(log)) 1205 /* FIXME: need better error handling */ 1206 DMWARN("log resume failed"); 1207 dm_rh_start_recovery(ms->rh); 1208} 1209 1210/* 1211 * device_status_char 1212 * @m: mirror device/leg we want the status of 1213 * 1214 * We return one character representing the most severe error 1215 * we have encountered. 1216 * A => Alive - No failures 1217 * D => Dead - A write failure occurred leaving mirror out-of-sync 1218 * S => Sync - A sychronization failure occurred, mirror out-of-sync 1219 * R => Read - A read failure occurred, mirror data unaffected 1220 * 1221 * Returns: <char> 1222 */ 1223static char device_status_char(struct mirror *m) 1224{ 1225 if (!atomic_read(&(m->error_count))) 1226 return 'A'; 1227 1228 return (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' : 1229 (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' : 1230 (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U'; 1231} 1232 1233 1234static int mirror_status(struct dm_target *ti, status_type_t type, 1235 char *result, unsigned int maxlen) 1236{ 1237 unsigned int m, sz = 0; 1238 struct mirror_set *ms = (struct mirror_set *) ti->private; 1239 struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); 1240 char buffer[ms->nr_mirrors + 1]; 1241 1242 switch (type) { 1243 case STATUSTYPE_INFO: 1244 DMEMIT("%d ", ms->nr_mirrors); 1245 for (m = 0; m < ms->nr_mirrors; m++) { 1246 DMEMIT("%s ", ms->mirror[m].dev->name); 1247 buffer[m] = device_status_char(&(ms->mirror[m])); 1248 } 1249 buffer[m] = '\0'; 1250 1251 DMEMIT("%llu/%llu 1 %s ", 1252 (unsigned long long)log->type->get_sync_count(log), 1253 (unsigned long long)ms->nr_regions, buffer); 1254 1255 sz += log->type->status(log, type, result+sz, maxlen-sz); 1256 1257 break; 1258 1259 case STATUSTYPE_TABLE: 1260 sz = log->type->status(log, type, result, maxlen); 1261 1262 DMEMIT("%d", ms->nr_mirrors); 1263 for (m = 0; m < ms->nr_mirrors; m++) 1264 DMEMIT(" %s %llu", ms->mirror[m].dev->name, 1265 (unsigned long long)ms->mirror[m].offset); 1266 1267 if (ms->features & DM_RAID1_HANDLE_ERRORS) 1268 DMEMIT(" 1 handle_errors"); 1269 } 1270 1271 return 0; 1272} 1273 1274static struct target_type mirror_target = { 1275 .name = "mirror", 1276 .version = {1, 0, 20}, 1277 .module = THIS_MODULE, 1278 .ctr = mirror_ctr, 1279 .dtr = mirror_dtr, 1280 .map = mirror_map, 1281 .end_io = mirror_end_io, 1282 .presuspend = mirror_presuspend, 1283 .postsuspend = mirror_postsuspend, 1284 .resume = mirror_resume, 1285 .status = mirror_status, 1286}; 1287 1288static int __init dm_mirror_init(void) 1289{ 1290 int r; 1291 1292 r = dm_register_target(&mirror_target); 1293 if (r < 0) 1294 DMERR("Failed to register mirror target"); 1295 1296 return r; 1297} 1298 1299static void __exit dm_mirror_exit(void) 1300{ 1301 int r; 1302 1303 r = dm_unregister_target(&mirror_target); 1304 if (r < 0) 1305 DMERR("unregister failed %d", r); 1306} 1307 1308/* Module hooks */ 1309module_init(dm_mirror_init); 1310module_exit(dm_mirror_exit); 1311 1312MODULE_DESCRIPTION(DM_NAME " mirror target"); 1313MODULE_AUTHOR("Joe Thornber"); 1314MODULE_LICENSE("GPL"); 1315