dm-raid1.c revision e4c8b3ba34cc1aeab451c7a5cc843c5fd62cbe3d
1/* 2 * Copyright (C) 2003 Sistina Software Limited. 3 * 4 * This file is released under the GPL. 5 */ 6 7#include "dm.h" 8#include "dm-bio-list.h" 9#include "dm-io.h" 10#include "dm-log.h" 11#include "kcopyd.h" 12 13#include <linux/ctype.h> 14#include <linux/init.h> 15#include <linux/mempool.h> 16#include <linux/module.h> 17#include <linux/pagemap.h> 18#include <linux/slab.h> 19#include <linux/time.h> 20#include <linux/vmalloc.h> 21#include <linux/workqueue.h> 22 23static struct workqueue_struct *_kmirrord_wq; 24static struct work_struct _kmirrord_work; 25 26static inline void wake(void) 27{ 28 queue_work(_kmirrord_wq, &_kmirrord_work); 29} 30 31/*----------------------------------------------------------------- 32 * Region hash 33 * 34 * The mirror splits itself up into discrete regions. Each 35 * region can be in one of three states: clean, dirty, 36 * nosync. There is no need to put clean regions in the hash. 37 * 38 * In addition to being present in the hash table a region _may_ 39 * be present on one of three lists. 40 * 41 * clean_regions: Regions on this list have no io pending to 42 * them, they are in sync, we are no longer interested in them, 43 * they are dull. rh_update_states() will remove them from the 44 * hash table. 45 * 46 * quiesced_regions: These regions have been spun down, ready 47 * for recovery. rh_recovery_start() will remove regions from 48 * this list and hand them to kmirrord, which will schedule the 49 * recovery io with kcopyd. 50 * 51 * recovered_regions: Regions that kcopyd has successfully 52 * recovered. rh_update_states() will now schedule any delayed 53 * io, up the recovery_count, and remove the region from the 54 * hash. 55 * 56 * There are 2 locks: 57 * A rw spin lock 'hash_lock' protects just the hash table, 58 * this is never held in write mode from interrupt context, 59 * which I believe means that we only have to disable irqs when 60 * doing a write lock. 61 * 62 * An ordinary spin lock 'region_lock' that protects the three 63 * lists in the region_hash, with the 'state', 'list' and 64 * 'bhs_delayed' fields of the regions. This is used from irq 65 * context, so all other uses will have to suspend local irqs. 66 *---------------------------------------------------------------*/ 67struct mirror_set; 68struct region_hash { 69 struct mirror_set *ms; 70 uint32_t region_size; 71 unsigned region_shift; 72 73 /* holds persistent region state */ 74 struct dirty_log *log; 75 76 /* hash table */ 77 rwlock_t hash_lock; 78 mempool_t *region_pool; 79 unsigned int mask; 80 unsigned int nr_buckets; 81 struct list_head *buckets; 82 83 spinlock_t region_lock; 84 struct semaphore recovery_count; 85 struct list_head clean_regions; 86 struct list_head quiesced_regions; 87 struct list_head recovered_regions; 88}; 89 90enum { 91 RH_CLEAN, 92 RH_DIRTY, 93 RH_NOSYNC, 94 RH_RECOVERING 95}; 96 97struct region { 98 struct region_hash *rh; /* FIXME: can we get rid of this ? */ 99 region_t key; 100 int state; 101 102 struct list_head hash_list; 103 struct list_head list; 104 105 atomic_t pending; 106 struct bio_list delayed_bios; 107}; 108 109 110/*----------------------------------------------------------------- 111 * Mirror set structures. 112 *---------------------------------------------------------------*/ 113struct mirror { 114 atomic_t error_count; 115 struct dm_dev *dev; 116 sector_t offset; 117}; 118 119struct mirror_set { 120 struct dm_target *ti; 121 struct list_head list; 122 struct region_hash rh; 123 struct kcopyd_client *kcopyd_client; 124 125 spinlock_t lock; /* protects the next two lists */ 126 struct bio_list reads; 127 struct bio_list writes; 128 129 /* recovery */ 130 region_t nr_regions; 131 int in_sync; 132 133 struct mirror *default_mirror; /* Default mirror */ 134 135 unsigned int nr_mirrors; 136 struct mirror mirror[0]; 137}; 138 139/* 140 * Conversion fns 141 */ 142static inline region_t bio_to_region(struct region_hash *rh, struct bio *bio) 143{ 144 return (bio->bi_sector - rh->ms->ti->begin) >> rh->region_shift; 145} 146 147static inline sector_t region_to_sector(struct region_hash *rh, region_t region) 148{ 149 return region << rh->region_shift; 150} 151 152/* FIXME move this */ 153static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw); 154 155#define MIN_REGIONS 64 156#define MAX_RECOVERY 1 157static int rh_init(struct region_hash *rh, struct mirror_set *ms, 158 struct dirty_log *log, uint32_t region_size, 159 region_t nr_regions) 160{ 161 unsigned int nr_buckets, max_buckets; 162 size_t i; 163 164 /* 165 * Calculate a suitable number of buckets for our hash 166 * table. 167 */ 168 max_buckets = nr_regions >> 6; 169 for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1) 170 ; 171 nr_buckets >>= 1; 172 173 rh->ms = ms; 174 rh->log = log; 175 rh->region_size = region_size; 176 rh->region_shift = ffs(region_size) - 1; 177 rwlock_init(&rh->hash_lock); 178 rh->mask = nr_buckets - 1; 179 rh->nr_buckets = nr_buckets; 180 181 rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets)); 182 if (!rh->buckets) { 183 DMERR("unable to allocate region hash memory"); 184 return -ENOMEM; 185 } 186 187 for (i = 0; i < nr_buckets; i++) 188 INIT_LIST_HEAD(rh->buckets + i); 189 190 spin_lock_init(&rh->region_lock); 191 sema_init(&rh->recovery_count, 0); 192 INIT_LIST_HEAD(&rh->clean_regions); 193 INIT_LIST_HEAD(&rh->quiesced_regions); 194 INIT_LIST_HEAD(&rh->recovered_regions); 195 196 rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS, 197 sizeof(struct region)); 198 if (!rh->region_pool) { 199 vfree(rh->buckets); 200 rh->buckets = NULL; 201 return -ENOMEM; 202 } 203 204 return 0; 205} 206 207static void rh_exit(struct region_hash *rh) 208{ 209 unsigned int h; 210 struct region *reg, *nreg; 211 212 BUG_ON(!list_empty(&rh->quiesced_regions)); 213 for (h = 0; h < rh->nr_buckets; h++) { 214 list_for_each_entry_safe(reg, nreg, rh->buckets + h, hash_list) { 215 BUG_ON(atomic_read(®->pending)); 216 mempool_free(reg, rh->region_pool); 217 } 218 } 219 220 if (rh->log) 221 dm_destroy_dirty_log(rh->log); 222 if (rh->region_pool) 223 mempool_destroy(rh->region_pool); 224 vfree(rh->buckets); 225} 226 227#define RH_HASH_MULT 2654435387U 228 229static inline unsigned int rh_hash(struct region_hash *rh, region_t region) 230{ 231 return (unsigned int) ((region * RH_HASH_MULT) >> 12) & rh->mask; 232} 233 234static struct region *__rh_lookup(struct region_hash *rh, region_t region) 235{ 236 struct region *reg; 237 238 list_for_each_entry (reg, rh->buckets + rh_hash(rh, region), hash_list) 239 if (reg->key == region) 240 return reg; 241 242 return NULL; 243} 244 245static void __rh_insert(struct region_hash *rh, struct region *reg) 246{ 247 unsigned int h = rh_hash(rh, reg->key); 248 list_add(®->hash_list, rh->buckets + h); 249} 250 251static struct region *__rh_alloc(struct region_hash *rh, region_t region) 252{ 253 struct region *reg, *nreg; 254 255 read_unlock(&rh->hash_lock); 256 nreg = mempool_alloc(rh->region_pool, GFP_NOIO); 257 nreg->state = rh->log->type->in_sync(rh->log, region, 1) ? 258 RH_CLEAN : RH_NOSYNC; 259 nreg->rh = rh; 260 nreg->key = region; 261 262 INIT_LIST_HEAD(&nreg->list); 263 264 atomic_set(&nreg->pending, 0); 265 bio_list_init(&nreg->delayed_bios); 266 write_lock_irq(&rh->hash_lock); 267 268 reg = __rh_lookup(rh, region); 269 if (reg) 270 /* we lost the race */ 271 mempool_free(nreg, rh->region_pool); 272 273 else { 274 __rh_insert(rh, nreg); 275 if (nreg->state == RH_CLEAN) { 276 spin_lock(&rh->region_lock); 277 list_add(&nreg->list, &rh->clean_regions); 278 spin_unlock(&rh->region_lock); 279 } 280 reg = nreg; 281 } 282 write_unlock_irq(&rh->hash_lock); 283 read_lock(&rh->hash_lock); 284 285 return reg; 286} 287 288static inline struct region *__rh_find(struct region_hash *rh, region_t region) 289{ 290 struct region *reg; 291 292 reg = __rh_lookup(rh, region); 293 if (!reg) 294 reg = __rh_alloc(rh, region); 295 296 return reg; 297} 298 299static int rh_state(struct region_hash *rh, region_t region, int may_block) 300{ 301 int r; 302 struct region *reg; 303 304 read_lock(&rh->hash_lock); 305 reg = __rh_lookup(rh, region); 306 read_unlock(&rh->hash_lock); 307 308 if (reg) 309 return reg->state; 310 311 /* 312 * The region wasn't in the hash, so we fall back to the 313 * dirty log. 314 */ 315 r = rh->log->type->in_sync(rh->log, region, may_block); 316 317 /* 318 * Any error from the dirty log (eg. -EWOULDBLOCK) gets 319 * taken as a RH_NOSYNC 320 */ 321 return r == 1 ? RH_CLEAN : RH_NOSYNC; 322} 323 324static inline int rh_in_sync(struct region_hash *rh, 325 region_t region, int may_block) 326{ 327 int state = rh_state(rh, region, may_block); 328 return state == RH_CLEAN || state == RH_DIRTY; 329} 330 331static void dispatch_bios(struct mirror_set *ms, struct bio_list *bio_list) 332{ 333 struct bio *bio; 334 335 while ((bio = bio_list_pop(bio_list))) { 336 queue_bio(ms, bio, WRITE); 337 } 338} 339 340static void rh_update_states(struct region_hash *rh) 341{ 342 struct region *reg, *next; 343 344 LIST_HEAD(clean); 345 LIST_HEAD(recovered); 346 347 /* 348 * Quickly grab the lists. 349 */ 350 write_lock_irq(&rh->hash_lock); 351 spin_lock(&rh->region_lock); 352 if (!list_empty(&rh->clean_regions)) { 353 list_splice(&rh->clean_regions, &clean); 354 INIT_LIST_HEAD(&rh->clean_regions); 355 356 list_for_each_entry (reg, &clean, list) { 357 rh->log->type->clear_region(rh->log, reg->key); 358 list_del(®->hash_list); 359 } 360 } 361 362 if (!list_empty(&rh->recovered_regions)) { 363 list_splice(&rh->recovered_regions, &recovered); 364 INIT_LIST_HEAD(&rh->recovered_regions); 365 366 list_for_each_entry (reg, &recovered, list) 367 list_del(®->hash_list); 368 } 369 spin_unlock(&rh->region_lock); 370 write_unlock_irq(&rh->hash_lock); 371 372 /* 373 * All the regions on the recovered and clean lists have 374 * now been pulled out of the system, so no need to do 375 * any more locking. 376 */ 377 list_for_each_entry_safe (reg, next, &recovered, list) { 378 rh->log->type->clear_region(rh->log, reg->key); 379 rh->log->type->complete_resync_work(rh->log, reg->key, 1); 380 dispatch_bios(rh->ms, ®->delayed_bios); 381 up(&rh->recovery_count); 382 mempool_free(reg, rh->region_pool); 383 } 384 385 if (!list_empty(&recovered)) 386 rh->log->type->flush(rh->log); 387 388 list_for_each_entry_safe (reg, next, &clean, list) 389 mempool_free(reg, rh->region_pool); 390} 391 392static void rh_inc(struct region_hash *rh, region_t region) 393{ 394 struct region *reg; 395 396 read_lock(&rh->hash_lock); 397 reg = __rh_find(rh, region); 398 399 spin_lock_irq(&rh->region_lock); 400 atomic_inc(®->pending); 401 402 if (reg->state == RH_CLEAN) { 403 reg->state = RH_DIRTY; 404 list_del_init(®->list); /* take off the clean list */ 405 spin_unlock_irq(&rh->region_lock); 406 407 rh->log->type->mark_region(rh->log, reg->key); 408 } else 409 spin_unlock_irq(&rh->region_lock); 410 411 412 read_unlock(&rh->hash_lock); 413} 414 415static void rh_inc_pending(struct region_hash *rh, struct bio_list *bios) 416{ 417 struct bio *bio; 418 419 for (bio = bios->head; bio; bio = bio->bi_next) 420 rh_inc(rh, bio_to_region(rh, bio)); 421} 422 423static void rh_dec(struct region_hash *rh, region_t region) 424{ 425 unsigned long flags; 426 struct region *reg; 427 int should_wake = 0; 428 429 read_lock(&rh->hash_lock); 430 reg = __rh_lookup(rh, region); 431 read_unlock(&rh->hash_lock); 432 433 spin_lock_irqsave(&rh->region_lock, flags); 434 if (atomic_dec_and_test(®->pending)) { 435 /* 436 * There is no pending I/O for this region. 437 * We can move the region to corresponding list for next action. 438 * At this point, the region is not yet connected to any list. 439 * 440 * If the state is RH_NOSYNC, the region should be kept off 441 * from clean list. 442 * The hash entry for RH_NOSYNC will remain in memory 443 * until the region is recovered or the map is reloaded. 444 */ 445 446 /* do nothing for RH_NOSYNC */ 447 if (reg->state == RH_RECOVERING) { 448 list_add_tail(®->list, &rh->quiesced_regions); 449 } else if (reg->state == RH_DIRTY) { 450 reg->state = RH_CLEAN; 451 list_add(®->list, &rh->clean_regions); 452 } 453 should_wake = 1; 454 } 455 spin_unlock_irqrestore(&rh->region_lock, flags); 456 457 if (should_wake) 458 wake(); 459} 460 461/* 462 * Starts quiescing a region in preparation for recovery. 463 */ 464static int __rh_recovery_prepare(struct region_hash *rh) 465{ 466 int r; 467 struct region *reg; 468 region_t region; 469 470 /* 471 * Ask the dirty log what's next. 472 */ 473 r = rh->log->type->get_resync_work(rh->log, ®ion); 474 if (r <= 0) 475 return r; 476 477 /* 478 * Get this region, and start it quiescing by setting the 479 * recovering flag. 480 */ 481 read_lock(&rh->hash_lock); 482 reg = __rh_find(rh, region); 483 read_unlock(&rh->hash_lock); 484 485 spin_lock_irq(&rh->region_lock); 486 reg->state = RH_RECOVERING; 487 488 /* Already quiesced ? */ 489 if (atomic_read(®->pending)) 490 list_del_init(®->list); 491 else 492 list_move(®->list, &rh->quiesced_regions); 493 494 spin_unlock_irq(&rh->region_lock); 495 496 return 1; 497} 498 499static void rh_recovery_prepare(struct region_hash *rh) 500{ 501 while (!down_trylock(&rh->recovery_count)) 502 if (__rh_recovery_prepare(rh) <= 0) { 503 up(&rh->recovery_count); 504 break; 505 } 506} 507 508/* 509 * Returns any quiesced regions. 510 */ 511static struct region *rh_recovery_start(struct region_hash *rh) 512{ 513 struct region *reg = NULL; 514 515 spin_lock_irq(&rh->region_lock); 516 if (!list_empty(&rh->quiesced_regions)) { 517 reg = list_entry(rh->quiesced_regions.next, 518 struct region, list); 519 list_del_init(®->list); /* remove from the quiesced list */ 520 } 521 spin_unlock_irq(&rh->region_lock); 522 523 return reg; 524} 525 526/* FIXME: success ignored for now */ 527static void rh_recovery_end(struct region *reg, int success) 528{ 529 struct region_hash *rh = reg->rh; 530 531 spin_lock_irq(&rh->region_lock); 532 list_add(®->list, ®->rh->recovered_regions); 533 spin_unlock_irq(&rh->region_lock); 534 535 wake(); 536} 537 538static void rh_flush(struct region_hash *rh) 539{ 540 rh->log->type->flush(rh->log); 541} 542 543static void rh_delay(struct region_hash *rh, struct bio *bio) 544{ 545 struct region *reg; 546 547 read_lock(&rh->hash_lock); 548 reg = __rh_find(rh, bio_to_region(rh, bio)); 549 bio_list_add(®->delayed_bios, bio); 550 read_unlock(&rh->hash_lock); 551} 552 553static void rh_stop_recovery(struct region_hash *rh) 554{ 555 int i; 556 557 /* wait for any recovering regions */ 558 for (i = 0; i < MAX_RECOVERY; i++) 559 down(&rh->recovery_count); 560} 561 562static void rh_start_recovery(struct region_hash *rh) 563{ 564 int i; 565 566 for (i = 0; i < MAX_RECOVERY; i++) 567 up(&rh->recovery_count); 568 569 wake(); 570} 571 572/* 573 * Every mirror should look like this one. 574 */ 575#define DEFAULT_MIRROR 0 576 577/* 578 * This is yucky. We squirrel the mirror_set struct away inside 579 * bi_next for write buffers. This is safe since the bh 580 * doesn't get submitted to the lower levels of block layer. 581 */ 582static struct mirror_set *bio_get_ms(struct bio *bio) 583{ 584 return (struct mirror_set *) bio->bi_next; 585} 586 587static void bio_set_ms(struct bio *bio, struct mirror_set *ms) 588{ 589 bio->bi_next = (struct bio *) ms; 590} 591 592/*----------------------------------------------------------------- 593 * Recovery. 594 * 595 * When a mirror is first activated we may find that some regions 596 * are in the no-sync state. We have to recover these by 597 * recopying from the default mirror to all the others. 598 *---------------------------------------------------------------*/ 599static void recovery_complete(int read_err, unsigned int write_err, 600 void *context) 601{ 602 struct region *reg = (struct region *) context; 603 604 /* FIXME: better error handling */ 605 rh_recovery_end(reg, read_err || write_err); 606} 607 608static int recover(struct mirror_set *ms, struct region *reg) 609{ 610 int r; 611 unsigned int i; 612 struct io_region from, to[KCOPYD_MAX_REGIONS], *dest; 613 struct mirror *m; 614 unsigned long flags = 0; 615 616 /* fill in the source */ 617 m = ms->default_mirror; 618 from.bdev = m->dev->bdev; 619 from.sector = m->offset + region_to_sector(reg->rh, reg->key); 620 if (reg->key == (ms->nr_regions - 1)) { 621 /* 622 * The final region may be smaller than 623 * region_size. 624 */ 625 from.count = ms->ti->len & (reg->rh->region_size - 1); 626 if (!from.count) 627 from.count = reg->rh->region_size; 628 } else 629 from.count = reg->rh->region_size; 630 631 /* fill in the destinations */ 632 for (i = 0, dest = to; i < ms->nr_mirrors; i++) { 633 if (&ms->mirror[i] == ms->default_mirror) 634 continue; 635 636 m = ms->mirror + i; 637 dest->bdev = m->dev->bdev; 638 dest->sector = m->offset + region_to_sector(reg->rh, reg->key); 639 dest->count = from.count; 640 dest++; 641 } 642 643 /* hand to kcopyd */ 644 set_bit(KCOPYD_IGNORE_ERROR, &flags); 645 r = kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to, flags, 646 recovery_complete, reg); 647 648 return r; 649} 650 651static void do_recovery(struct mirror_set *ms) 652{ 653 int r; 654 struct region *reg; 655 struct dirty_log *log = ms->rh.log; 656 657 /* 658 * Start quiescing some regions. 659 */ 660 rh_recovery_prepare(&ms->rh); 661 662 /* 663 * Copy any already quiesced regions. 664 */ 665 while ((reg = rh_recovery_start(&ms->rh))) { 666 r = recover(ms, reg); 667 if (r) 668 rh_recovery_end(reg, 0); 669 } 670 671 /* 672 * Update the in sync flag. 673 */ 674 if (!ms->in_sync && 675 (log->type->get_sync_count(log) == ms->nr_regions)) { 676 /* the sync is complete */ 677 dm_table_event(ms->ti->table); 678 ms->in_sync = 1; 679 } 680} 681 682/*----------------------------------------------------------------- 683 * Reads 684 *---------------------------------------------------------------*/ 685static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector) 686{ 687 /* FIXME: add read balancing */ 688 return ms->default_mirror; 689} 690 691/* 692 * remap a buffer to a particular mirror. 693 */ 694static void map_bio(struct mirror_set *ms, struct mirror *m, struct bio *bio) 695{ 696 bio->bi_bdev = m->dev->bdev; 697 bio->bi_sector = m->offset + (bio->bi_sector - ms->ti->begin); 698} 699 700static void do_reads(struct mirror_set *ms, struct bio_list *reads) 701{ 702 region_t region; 703 struct bio *bio; 704 struct mirror *m; 705 706 while ((bio = bio_list_pop(reads))) { 707 region = bio_to_region(&ms->rh, bio); 708 709 /* 710 * We can only read balance if the region is in sync. 711 */ 712 if (rh_in_sync(&ms->rh, region, 0)) 713 m = choose_mirror(ms, bio->bi_sector); 714 else 715 m = ms->default_mirror; 716 717 map_bio(ms, m, bio); 718 generic_make_request(bio); 719 } 720} 721 722/*----------------------------------------------------------------- 723 * Writes. 724 * 725 * We do different things with the write io depending on the 726 * state of the region that it's in: 727 * 728 * SYNC: increment pending, use kcopyd to write to *all* mirrors 729 * RECOVERING: delay the io until recovery completes 730 * NOSYNC: increment pending, just write to the default mirror 731 *---------------------------------------------------------------*/ 732static void write_callback(unsigned long error, void *context) 733{ 734 unsigned int i; 735 int uptodate = 1; 736 struct bio *bio = (struct bio *) context; 737 struct mirror_set *ms; 738 739 ms = bio_get_ms(bio); 740 bio_set_ms(bio, NULL); 741 742 /* 743 * NOTE: We don't decrement the pending count here, 744 * instead it is done by the targets endio function. 745 * This way we handle both writes to SYNC and NOSYNC 746 * regions with the same code. 747 */ 748 749 if (error) { 750 /* 751 * only error the io if all mirrors failed. 752 * FIXME: bogus 753 */ 754 uptodate = 0; 755 for (i = 0; i < ms->nr_mirrors; i++) 756 if (!test_bit(i, &error)) { 757 uptodate = 1; 758 break; 759 } 760 } 761 bio_endio(bio, bio->bi_size, 0); 762} 763 764static void do_write(struct mirror_set *ms, struct bio *bio) 765{ 766 unsigned int i; 767 struct io_region io[KCOPYD_MAX_REGIONS+1]; 768 struct mirror *m; 769 770 for (i = 0; i < ms->nr_mirrors; i++) { 771 m = ms->mirror + i; 772 773 io[i].bdev = m->dev->bdev; 774 io[i].sector = m->offset + (bio->bi_sector - ms->ti->begin); 775 io[i].count = bio->bi_size >> 9; 776 } 777 778 bio_set_ms(bio, ms); 779 dm_io_async_bvec(ms->nr_mirrors, io, WRITE, 780 bio->bi_io_vec + bio->bi_idx, 781 write_callback, bio); 782} 783 784static void do_writes(struct mirror_set *ms, struct bio_list *writes) 785{ 786 int state; 787 struct bio *bio; 788 struct bio_list sync, nosync, recover, *this_list = NULL; 789 790 if (!writes->head) 791 return; 792 793 /* 794 * Classify each write. 795 */ 796 bio_list_init(&sync); 797 bio_list_init(&nosync); 798 bio_list_init(&recover); 799 800 while ((bio = bio_list_pop(writes))) { 801 state = rh_state(&ms->rh, bio_to_region(&ms->rh, bio), 1); 802 switch (state) { 803 case RH_CLEAN: 804 case RH_DIRTY: 805 this_list = &sync; 806 break; 807 808 case RH_NOSYNC: 809 this_list = &nosync; 810 break; 811 812 case RH_RECOVERING: 813 this_list = &recover; 814 break; 815 } 816 817 bio_list_add(this_list, bio); 818 } 819 820 /* 821 * Increment the pending counts for any regions that will 822 * be written to (writes to recover regions are going to 823 * be delayed). 824 */ 825 rh_inc_pending(&ms->rh, &sync); 826 rh_inc_pending(&ms->rh, &nosync); 827 rh_flush(&ms->rh); 828 829 /* 830 * Dispatch io. 831 */ 832 while ((bio = bio_list_pop(&sync))) 833 do_write(ms, bio); 834 835 while ((bio = bio_list_pop(&recover))) 836 rh_delay(&ms->rh, bio); 837 838 while ((bio = bio_list_pop(&nosync))) { 839 map_bio(ms, ms->default_mirror, bio); 840 generic_make_request(bio); 841 } 842} 843 844/*----------------------------------------------------------------- 845 * kmirrord 846 *---------------------------------------------------------------*/ 847static LIST_HEAD(_mirror_sets); 848static DECLARE_RWSEM(_mirror_sets_lock); 849 850static void do_mirror(struct mirror_set *ms) 851{ 852 struct bio_list reads, writes; 853 854 spin_lock(&ms->lock); 855 reads = ms->reads; 856 writes = ms->writes; 857 bio_list_init(&ms->reads); 858 bio_list_init(&ms->writes); 859 spin_unlock(&ms->lock); 860 861 rh_update_states(&ms->rh); 862 do_recovery(ms); 863 do_reads(ms, &reads); 864 do_writes(ms, &writes); 865} 866 867static void do_work(void *ignored) 868{ 869 struct mirror_set *ms; 870 871 down_read(&_mirror_sets_lock); 872 list_for_each_entry (ms, &_mirror_sets, list) 873 do_mirror(ms); 874 up_read(&_mirror_sets_lock); 875} 876 877/*----------------------------------------------------------------- 878 * Target functions 879 *---------------------------------------------------------------*/ 880static struct mirror_set *alloc_context(unsigned int nr_mirrors, 881 uint32_t region_size, 882 struct dm_target *ti, 883 struct dirty_log *dl) 884{ 885 size_t len; 886 struct mirror_set *ms = NULL; 887 888 if (array_too_big(sizeof(*ms), sizeof(ms->mirror[0]), nr_mirrors)) 889 return NULL; 890 891 len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors); 892 893 ms = kmalloc(len, GFP_KERNEL); 894 if (!ms) { 895 ti->error = "dm-mirror: Cannot allocate mirror context"; 896 return NULL; 897 } 898 899 memset(ms, 0, len); 900 spin_lock_init(&ms->lock); 901 902 ms->ti = ti; 903 ms->nr_mirrors = nr_mirrors; 904 ms->nr_regions = dm_sector_div_up(ti->len, region_size); 905 ms->in_sync = 0; 906 ms->default_mirror = &ms->mirror[DEFAULT_MIRROR]; 907 908 if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) { 909 ti->error = "dm-mirror: Error creating dirty region hash"; 910 kfree(ms); 911 return NULL; 912 } 913 914 return ms; 915} 916 917static void free_context(struct mirror_set *ms, struct dm_target *ti, 918 unsigned int m) 919{ 920 while (m--) 921 dm_put_device(ti, ms->mirror[m].dev); 922 923 rh_exit(&ms->rh); 924 kfree(ms); 925} 926 927static inline int _check_region_size(struct dm_target *ti, uint32_t size) 928{ 929 return !(size % (PAGE_SIZE >> 9) || (size & (size - 1)) || 930 size > ti->len); 931} 932 933static int get_mirror(struct mirror_set *ms, struct dm_target *ti, 934 unsigned int mirror, char **argv) 935{ 936 unsigned long long offset; 937 938 if (sscanf(argv[1], "%llu", &offset) != 1) { 939 ti->error = "dm-mirror: Invalid offset"; 940 return -EINVAL; 941 } 942 943 if (dm_get_device(ti, argv[0], offset, ti->len, 944 dm_table_get_mode(ti->table), 945 &ms->mirror[mirror].dev)) { 946 ti->error = "dm-mirror: Device lookup failure"; 947 return -ENXIO; 948 } 949 950 ms->mirror[mirror].offset = offset; 951 952 return 0; 953} 954 955static int add_mirror_set(struct mirror_set *ms) 956{ 957 down_write(&_mirror_sets_lock); 958 list_add_tail(&ms->list, &_mirror_sets); 959 up_write(&_mirror_sets_lock); 960 wake(); 961 962 return 0; 963} 964 965static void del_mirror_set(struct mirror_set *ms) 966{ 967 down_write(&_mirror_sets_lock); 968 list_del(&ms->list); 969 up_write(&_mirror_sets_lock); 970} 971 972/* 973 * Create dirty log: log_type #log_params <log_params> 974 */ 975static struct dirty_log *create_dirty_log(struct dm_target *ti, 976 unsigned int argc, char **argv, 977 unsigned int *args_used) 978{ 979 unsigned int param_count; 980 struct dirty_log *dl; 981 982 if (argc < 2) { 983 ti->error = "dm-mirror: Insufficient mirror log arguments"; 984 return NULL; 985 } 986 987 if (sscanf(argv[1], "%u", ¶m_count) != 1) { 988 ti->error = "dm-mirror: Invalid mirror log argument count"; 989 return NULL; 990 } 991 992 *args_used = 2 + param_count; 993 994 if (argc < *args_used) { 995 ti->error = "dm-mirror: Insufficient mirror log arguments"; 996 return NULL; 997 } 998 999 dl = dm_create_dirty_log(argv[0], ti, param_count, argv + 2); 1000 if (!dl) { 1001 ti->error = "dm-mirror: Error creating mirror dirty log"; 1002 return NULL; 1003 } 1004 1005 if (!_check_region_size(ti, dl->type->get_region_size(dl))) { 1006 ti->error = "dm-mirror: Invalid region size"; 1007 dm_destroy_dirty_log(dl); 1008 return NULL; 1009 } 1010 1011 return dl; 1012} 1013 1014/* 1015 * Construct a mirror mapping: 1016 * 1017 * log_type #log_params <log_params> 1018 * #mirrors [mirror_path offset]{2,} 1019 * 1020 * log_type is "core" or "disk" 1021 * #log_params is between 1 and 3 1022 */ 1023#define DM_IO_PAGES 64 1024static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1025{ 1026 int r; 1027 unsigned int nr_mirrors, m, args_used; 1028 struct mirror_set *ms; 1029 struct dirty_log *dl; 1030 1031 dl = create_dirty_log(ti, argc, argv, &args_used); 1032 if (!dl) 1033 return -EINVAL; 1034 1035 argv += args_used; 1036 argc -= args_used; 1037 1038 if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 || 1039 nr_mirrors < 2 || nr_mirrors > KCOPYD_MAX_REGIONS + 1) { 1040 ti->error = "dm-mirror: Invalid number of mirrors"; 1041 dm_destroy_dirty_log(dl); 1042 return -EINVAL; 1043 } 1044 1045 argv++, argc--; 1046 1047 if (argc != nr_mirrors * 2) { 1048 ti->error = "dm-mirror: Wrong number of mirror arguments"; 1049 dm_destroy_dirty_log(dl); 1050 return -EINVAL; 1051 } 1052 1053 ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl); 1054 if (!ms) { 1055 dm_destroy_dirty_log(dl); 1056 return -ENOMEM; 1057 } 1058 1059 /* Get the mirror parameter sets */ 1060 for (m = 0; m < nr_mirrors; m++) { 1061 r = get_mirror(ms, ti, m, argv); 1062 if (r) { 1063 free_context(ms, ti, m); 1064 return r; 1065 } 1066 argv += 2; 1067 argc -= 2; 1068 } 1069 1070 ti->private = ms; 1071 ti->split_io = ms->rh.region_size; 1072 1073 r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client); 1074 if (r) { 1075 free_context(ms, ti, ms->nr_mirrors); 1076 return r; 1077 } 1078 1079 add_mirror_set(ms); 1080 return 0; 1081} 1082 1083static void mirror_dtr(struct dm_target *ti) 1084{ 1085 struct mirror_set *ms = (struct mirror_set *) ti->private; 1086 1087 del_mirror_set(ms); 1088 kcopyd_client_destroy(ms->kcopyd_client); 1089 free_context(ms, ti, ms->nr_mirrors); 1090} 1091 1092static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw) 1093{ 1094 int should_wake = 0; 1095 struct bio_list *bl; 1096 1097 bl = (rw == WRITE) ? &ms->writes : &ms->reads; 1098 spin_lock(&ms->lock); 1099 should_wake = !(bl->head); 1100 bio_list_add(bl, bio); 1101 spin_unlock(&ms->lock); 1102 1103 if (should_wake) 1104 wake(); 1105} 1106 1107/* 1108 * Mirror mapping function 1109 */ 1110static int mirror_map(struct dm_target *ti, struct bio *bio, 1111 union map_info *map_context) 1112{ 1113 int r, rw = bio_rw(bio); 1114 struct mirror *m; 1115 struct mirror_set *ms = ti->private; 1116 1117 map_context->ll = bio_to_region(&ms->rh, bio); 1118 1119 if (rw == WRITE) { 1120 queue_bio(ms, bio, rw); 1121 return 0; 1122 } 1123 1124 r = ms->rh.log->type->in_sync(ms->rh.log, 1125 bio_to_region(&ms->rh, bio), 0); 1126 if (r < 0 && r != -EWOULDBLOCK) 1127 return r; 1128 1129 if (r == -EWOULDBLOCK) /* FIXME: ugly */ 1130 r = 0; 1131 1132 /* 1133 * We don't want to fast track a recovery just for a read 1134 * ahead. So we just let it silently fail. 1135 * FIXME: get rid of this. 1136 */ 1137 if (!r && rw == READA) 1138 return -EIO; 1139 1140 if (!r) { 1141 /* Pass this io over to the daemon */ 1142 queue_bio(ms, bio, rw); 1143 return 0; 1144 } 1145 1146 m = choose_mirror(ms, bio->bi_sector); 1147 if (!m) 1148 return -EIO; 1149 1150 map_bio(ms, m, bio); 1151 return 1; 1152} 1153 1154static int mirror_end_io(struct dm_target *ti, struct bio *bio, 1155 int error, union map_info *map_context) 1156{ 1157 int rw = bio_rw(bio); 1158 struct mirror_set *ms = (struct mirror_set *) ti->private; 1159 region_t region = map_context->ll; 1160 1161 /* 1162 * We need to dec pending if this was a write. 1163 */ 1164 if (rw == WRITE) 1165 rh_dec(&ms->rh, region); 1166 1167 return 0; 1168} 1169 1170static void mirror_postsuspend(struct dm_target *ti) 1171{ 1172 struct mirror_set *ms = (struct mirror_set *) ti->private; 1173 struct dirty_log *log = ms->rh.log; 1174 1175 rh_stop_recovery(&ms->rh); 1176 if (log->type->suspend && log->type->suspend(log)) 1177 /* FIXME: need better error handling */ 1178 DMWARN("log suspend failed"); 1179} 1180 1181static void mirror_resume(struct dm_target *ti) 1182{ 1183 struct mirror_set *ms = (struct mirror_set *) ti->private; 1184 struct dirty_log *log = ms->rh.log; 1185 if (log->type->resume && log->type->resume(log)) 1186 /* FIXME: need better error handling */ 1187 DMWARN("log resume failed"); 1188 rh_start_recovery(&ms->rh); 1189} 1190 1191static int mirror_status(struct dm_target *ti, status_type_t type, 1192 char *result, unsigned int maxlen) 1193{ 1194 unsigned int m, sz; 1195 struct mirror_set *ms = (struct mirror_set *) ti->private; 1196 1197 sz = ms->rh.log->type->status(ms->rh.log, type, result, maxlen); 1198 1199 switch (type) { 1200 case STATUSTYPE_INFO: 1201 DMEMIT("%d ", ms->nr_mirrors); 1202 for (m = 0; m < ms->nr_mirrors; m++) 1203 DMEMIT("%s ", ms->mirror[m].dev->name); 1204 1205 DMEMIT("%llu/%llu", 1206 (unsigned long long)ms->rh.log->type-> 1207 get_sync_count(ms->rh.log), 1208 (unsigned long long)ms->nr_regions); 1209 break; 1210 1211 case STATUSTYPE_TABLE: 1212 DMEMIT("%d ", ms->nr_mirrors); 1213 for (m = 0; m < ms->nr_mirrors; m++) 1214 DMEMIT("%s %llu ", ms->mirror[m].dev->name, 1215 (unsigned long long)ms->mirror[m].offset); 1216 } 1217 1218 return 0; 1219} 1220 1221static struct target_type mirror_target = { 1222 .name = "mirror", 1223 .version = {1, 0, 1}, 1224 .module = THIS_MODULE, 1225 .ctr = mirror_ctr, 1226 .dtr = mirror_dtr, 1227 .map = mirror_map, 1228 .end_io = mirror_end_io, 1229 .postsuspend = mirror_postsuspend, 1230 .resume = mirror_resume, 1231 .status = mirror_status, 1232}; 1233 1234static int __init dm_mirror_init(void) 1235{ 1236 int r; 1237 1238 r = dm_dirty_log_init(); 1239 if (r) 1240 return r; 1241 1242 _kmirrord_wq = create_singlethread_workqueue("kmirrord"); 1243 if (!_kmirrord_wq) { 1244 DMERR("couldn't start kmirrord"); 1245 dm_dirty_log_exit(); 1246 return r; 1247 } 1248 INIT_WORK(&_kmirrord_work, do_work, NULL); 1249 1250 r = dm_register_target(&mirror_target); 1251 if (r < 0) { 1252 DMERR("%s: Failed to register mirror target", 1253 mirror_target.name); 1254 dm_dirty_log_exit(); 1255 destroy_workqueue(_kmirrord_wq); 1256 } 1257 1258 return r; 1259} 1260 1261static void __exit dm_mirror_exit(void) 1262{ 1263 int r; 1264 1265 r = dm_unregister_target(&mirror_target); 1266 if (r < 0) 1267 DMERR("%s: unregister failed %d", mirror_target.name, r); 1268 1269 destroy_workqueue(_kmirrord_wq); 1270 dm_dirty_log_exit(); 1271} 1272 1273/* Module hooks */ 1274module_init(dm_mirror_init); 1275module_exit(dm_mirror_exit); 1276 1277MODULE_DESCRIPTION(DM_NAME " mirror target"); 1278MODULE_AUTHOR("Joe Thornber"); 1279MODULE_LICENSE("GPL"); 1280