1 /* 2 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. 3 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved. 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include "dm.h" 9 #include "dm-uevent.h" 10 11 #include <linux/init.h> 12 #include <linux/module.h> 13 #include <linux/mutex.h> 14 #include <linux/moduleparam.h> 15 #include <linux/blkpg.h> 16 #include <linux/bio.h> 17 #include <linux/mempool.h> 18 #include <linux/slab.h> 19 #include <linux/idr.h> 20 #include <linux/hdreg.h> 21 #include <linux/delay.h> 22 23 #include <trace/events/block.h> 24 25 #define DM_MSG_PREFIX "core" 26 27 #ifdef CONFIG_PRINTK 28 /* 29 * ratelimit state to be used in DMXXX_LIMIT(). 30 */ 31 DEFINE_RATELIMIT_STATE(dm_ratelimit_state, 32 DEFAULT_RATELIMIT_INTERVAL, 33 DEFAULT_RATELIMIT_BURST); 34 EXPORT_SYMBOL(dm_ratelimit_state); 35 #endif 36 37 /* 38 * Cookies are numeric values sent with CHANGE and REMOVE 39 * uevents while resuming, removing or renaming the device. 40 */ 41 #define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE" 42 #define DM_COOKIE_LENGTH 24 43 44 static const char *_name = DM_NAME; 45 46 static unsigned int major = 0; 47 static unsigned int _major = 0; 48 49 static DEFINE_IDR(_minor_idr); 50 51 static DEFINE_SPINLOCK(_minor_lock); 52 53 static void do_deferred_remove(struct work_struct *w); 54 55 static DECLARE_WORK(deferred_remove_work, do_deferred_remove); 56 57 /* 58 * For bio-based dm. 59 * One of these is allocated per bio. 60 */ 61 struct dm_io { 62 struct mapped_device *md; 63 int error; 64 atomic_t io_count; 65 struct bio *bio; 66 unsigned long start_time; 67 spinlock_t endio_lock; 68 struct dm_stats_aux stats_aux; 69 }; 70 71 /* 72 * For request-based dm. 73 * One of these is allocated per request. 74 */ 75 struct dm_rq_target_io { 76 struct mapped_device *md; 77 struct dm_target *ti; 78 struct request *orig, clone; 79 int error; 80 union map_info info; 81 }; 82 83 /* 84 * For request-based dm - the bio clones we allocate are embedded in these 85 * structs. 86 * 87 * We allocate these with bio_alloc_bioset, using the front_pad parameter when 88 * the bioset is created - this means the bio has to come at the end of the 89 * struct. 90 */ 91 struct dm_rq_clone_bio_info { 92 struct bio *orig; 93 struct dm_rq_target_io *tio; 94 struct bio clone; 95 }; 96 97 union map_info *dm_get_mapinfo(struct bio *bio) 98 { 99 if (bio && bio->bi_private) 100 return &((struct dm_target_io *)bio->bi_private)->info; 101 return NULL; 102 } 103 104 union map_info *dm_get_rq_mapinfo(struct request *rq) 105 { 106 if (rq && rq->end_io_data) 107 return &((struct dm_rq_target_io *)rq->end_io_data)->info; 108 return NULL; 109 } 110 EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo); 111 112 #define MINOR_ALLOCED ((void *)-1) 113 114 /* 115 * Bits for the md->flags field. 116 */ 117 #define DMF_BLOCK_IO_FOR_SUSPEND 0 118 #define DMF_SUSPENDED 1 119 #define DMF_FROZEN 2 120 #define DMF_FREEING 3 121 #define DMF_DELETING 4 122 #define DMF_NOFLUSH_SUSPENDING 5 123 #define DMF_MERGE_IS_OPTIONAL 6 124 #define DMF_DEFERRED_REMOVE 7 125 126 /* 127 * A dummy definition to make RCU happy. 128 * struct dm_table should never be dereferenced in this file. 129 */ 130 struct dm_table { 131 int undefined__; 132 }; 133 134 /* 135 * Work processed by per-device workqueue. 136 */ 137 struct mapped_device { 138 struct srcu_struct io_barrier; 139 struct mutex suspend_lock; 140 atomic_t holders; 141 atomic_t open_count; 142 143 /* 144 * The current mapping. 145 * Use dm_get_live_table{_fast} or take suspend_lock for 146 * dereference. 147 */ 148 struct dm_table *map; 149 150 unsigned long flags; 151 152 struct request_queue *queue; 153 unsigned type; 154 /* Protect queue and type against concurrent access. */ 155 struct mutex type_lock; 156 157 struct target_type *immutable_target_type; 158 159 struct gendisk *disk; 160 char name[16]; 161 162 void *interface_ptr; 163 164 /* 165 * A list of ios that arrived while we were suspended. 166 */ 167 atomic_t pending[2]; 168 wait_queue_head_t wait; 169 struct work_struct work; 170 struct bio_list deferred; 171 spinlock_t deferred_lock; 172 173 /* 174 * Processing queue (flush) 175 */ 176 struct workqueue_struct *wq; 177 178 /* 179 * io objects are allocated from here. 180 */ 181 mempool_t *io_pool; 182 183 struct bio_set *bs; 184 185 /* 186 * Event handling. 187 */ 188 atomic_t event_nr; 189 wait_queue_head_t eventq; 190 atomic_t uevent_seq; 191 struct list_head uevent_list; 192 spinlock_t uevent_lock; /* Protect access to uevent_list */ 193 194 /* 195 * freeze/thaw support require holding onto a super block 196 */ 197 struct super_block *frozen_sb; 198 struct block_device *bdev; 199 200 /* forced geometry settings */ 201 struct hd_geometry geometry; 202 203 /* sysfs handle */ 204 struct kobject kobj; 205 206 /* wait until the kobject is released */ 207 struct completion kobj_completion; 208 209 /* zero-length flush that will be cloned and submitted to targets */ 210 struct bio flush_bio; 211 212 struct dm_stats stats; 213 }; 214 215 /* 216 * For mempools pre-allocation at the table loading time. 217 */ 218 struct dm_md_mempools { 219 mempool_t *io_pool; 220 struct bio_set *bs; 221 }; 222 223 #define RESERVED_BIO_BASED_IOS 16 224 #define RESERVED_REQUEST_BASED_IOS 256 225 #define RESERVED_MAX_IOS 1024 226 static struct kmem_cache *_io_cache; 227 static struct kmem_cache *_rq_tio_cache; 228 229 /* 230 * Bio-based DM's mempools' reserved IOs set by the user. 231 */ 232 static unsigned reserved_bio_based_ios = RESERVED_BIO_BASED_IOS; 233 234 /* 235 * Request-based DM's mempools' reserved IOs set by the user. 236 */ 237 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS; 238 239 static unsigned __dm_get_reserved_ios(unsigned *reserved_ios, 240 unsigned def, unsigned max) 241 { 242 unsigned ios = ACCESS_ONCE(*reserved_ios); 243 unsigned modified_ios = 0; 244 245 if (!ios) 246 modified_ios = def; 247 else if (ios > max) 248 modified_ios = max; 249 250 if (modified_ios) { 251 (void)cmpxchg(reserved_ios, ios, modified_ios); 252 ios = modified_ios; 253 } 254 255 return ios; 256 } 257 258 unsigned dm_get_reserved_bio_based_ios(void) 259 { 260 return __dm_get_reserved_ios(&reserved_bio_based_ios, 261 RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS); 262 } 263 EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios); 264 265 unsigned dm_get_reserved_rq_based_ios(void) 266 { 267 return __dm_get_reserved_ios(&reserved_rq_based_ios, 268 RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS); 269 } 270 EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios); 271 272 static int __init local_init(void) 273 { 274 int r = -ENOMEM; 275 276 /* allocate a slab for the dm_ios */ 277 _io_cache = KMEM_CACHE(dm_io, 0); 278 if (!_io_cache) 279 return r; 280 281 _rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0); 282 if (!_rq_tio_cache) 283 goto out_free_io_cache; 284 285 r = dm_uevent_init(); 286 if (r) 287 goto out_free_rq_tio_cache; 288 289 _major = major; 290 r = register_blkdev(_major, _name); 291 if (r < 0) 292 goto out_uevent_exit; 293 294 if (!_major) 295 _major = r; 296 297 return 0; 298 299 out_uevent_exit: 300 dm_uevent_exit(); 301 out_free_rq_tio_cache: 302 kmem_cache_destroy(_rq_tio_cache); 303 out_free_io_cache: 304 kmem_cache_destroy(_io_cache); 305 306 return r; 307 } 308 309 static void local_exit(void) 310 { 311 flush_scheduled_work(); 312 313 kmem_cache_destroy(_rq_tio_cache); 314 kmem_cache_destroy(_io_cache); 315 unregister_blkdev(_major, _name); 316 dm_uevent_exit(); 317 318 _major = 0; 319 320 DMINFO("cleaned up"); 321 } 322 323 static int (*_inits[])(void) __initdata = { 324 local_init, 325 dm_target_init, 326 dm_linear_init, 327 dm_stripe_init, 328 dm_io_init, 329 dm_kcopyd_init, 330 dm_interface_init, 331 dm_statistics_init, 332 }; 333 334 static void (*_exits[])(void) = { 335 local_exit, 336 dm_target_exit, 337 dm_linear_exit, 338 dm_stripe_exit, 339 dm_io_exit, 340 dm_kcopyd_exit, 341 dm_interface_exit, 342 dm_statistics_exit, 343 }; 344 345 static int __init dm_init(void) 346 { 347 const int count = ARRAY_SIZE(_inits); 348 349 int r, i; 350 351 for (i = 0; i < count; i++) { 352 r = _inits[i](); 353 if (r) 354 goto bad; 355 } 356 357 return 0; 358 359 bad: 360 while (i--) 361 _exits[i](); 362 363 return r; 364 } 365 366 static void __exit dm_exit(void) 367 { 368 int i = ARRAY_SIZE(_exits); 369 370 while (i--) 371 _exits[i](); 372 373 /* 374 * Should be empty by this point. 375 */ 376 idr_destroy(&_minor_idr); 377 } 378 379 /* 380 * Block device functions 381 */ 382 int dm_deleting_md(struct mapped_device *md) 383 { 384 return test_bit(DMF_DELETING, &md->flags); 385 } 386 387 static int dm_blk_open(struct block_device *bdev, fmode_t mode) 388 { 389 struct mapped_device *md; 390 391 spin_lock(&_minor_lock); 392 393 md = bdev->bd_disk->private_data; 394 if (!md) 395 goto out; 396 397 if (test_bit(DMF_FREEING, &md->flags) || 398 dm_deleting_md(md)) { 399 md = NULL; 400 goto out; 401 } 402 403 dm_get(md); 404 atomic_inc(&md->open_count); 405 406 out: 407 spin_unlock(&_minor_lock); 408 409 return md ? 0 : -ENXIO; 410 } 411 412 static void dm_blk_close(struct gendisk *disk, fmode_t mode) 413 { 414 struct mapped_device *md = disk->private_data; 415 416 spin_lock(&_minor_lock); 417 418 if (atomic_dec_and_test(&md->open_count) && 419 (test_bit(DMF_DEFERRED_REMOVE, &md->flags))) 420 schedule_work(&deferred_remove_work); 421 422 dm_put(md); 423 424 spin_unlock(&_minor_lock); 425 } 426 427 int dm_open_count(struct mapped_device *md) 428 { 429 return atomic_read(&md->open_count); 430 } 431 432 /* 433 * Guarantees nothing is using the device before it's deleted. 434 */ 435 int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred) 436 { 437 int r = 0; 438 439 spin_lock(&_minor_lock); 440 441 if (dm_open_count(md)) { 442 r = -EBUSY; 443 if (mark_deferred) 444 set_bit(DMF_DEFERRED_REMOVE, &md->flags); 445 } else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags)) 446 r = -EEXIST; 447 else 448 set_bit(DMF_DELETING, &md->flags); 449 450 spin_unlock(&_minor_lock); 451 452 return r; 453 } 454 455 int dm_cancel_deferred_remove(struct mapped_device *md) 456 { 457 int r = 0; 458 459 spin_lock(&_minor_lock); 460 461 if (test_bit(DMF_DELETING, &md->flags)) 462 r = -EBUSY; 463 else 464 clear_bit(DMF_DEFERRED_REMOVE, &md->flags); 465 466 spin_unlock(&_minor_lock); 467 468 return r; 469 } 470 471 static void do_deferred_remove(struct work_struct *w) 472 { 473 dm_deferred_remove(); 474 } 475 476 sector_t dm_get_size(struct mapped_device *md) 477 { 478 return get_capacity(md->disk); 479 } 480 481 struct dm_stats *dm_get_stats(struct mapped_device *md) 482 { 483 return &md->stats; 484 } 485 486 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo) 487 { 488 struct mapped_device *md = bdev->bd_disk->private_data; 489 490 return dm_get_geometry(md, geo); 491 } 492 493 static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode, 494 unsigned int cmd, unsigned long arg) 495 { 496 struct mapped_device *md = bdev->bd_disk->private_data; 497 int srcu_idx; 498 struct dm_table *map; 499 struct dm_target *tgt; 500 int r = -ENOTTY; 501 502 retry: 503 map = dm_get_live_table(md, &srcu_idx); 504 505 if (!map || !dm_table_get_size(map)) 506 goto out; 507 508 /* We only support devices that have a single target */ 509 if (dm_table_get_num_targets(map) != 1) 510 goto out; 511 512 tgt = dm_table_get_target(map, 0); 513 514 if (dm_suspended_md(md)) { 515 r = -EAGAIN; 516 goto out; 517 } 518 519 if (tgt->type->ioctl) 520 r = tgt->type->ioctl(tgt, cmd, arg); 521 522 out: 523 dm_put_live_table(md, srcu_idx); 524 525 if (r == -ENOTCONN) { 526 msleep(10); 527 goto retry; 528 } 529 530 return r; 531 } 532 533 static struct dm_io *alloc_io(struct mapped_device *md) 534 { 535 return mempool_alloc(md->io_pool, GFP_NOIO); 536 } 537 538 static void free_io(struct mapped_device *md, struct dm_io *io) 539 { 540 mempool_free(io, md->io_pool); 541 } 542 543 static void free_tio(struct mapped_device *md, struct dm_target_io *tio) 544 { 545 bio_put(&tio->clone); 546 } 547 548 static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md, 549 gfp_t gfp_mask) 550 { 551 return mempool_alloc(md->io_pool, gfp_mask); 552 } 553 554 static void free_rq_tio(struct dm_rq_target_io *tio) 555 { 556 mempool_free(tio, tio->md->io_pool); 557 } 558 559 static int md_in_flight(struct mapped_device *md) 560 { 561 return atomic_read(&md->pending[READ]) + 562 atomic_read(&md->pending[WRITE]); 563 } 564 565 static void start_io_acct(struct dm_io *io) 566 { 567 struct mapped_device *md = io->md; 568 struct bio *bio = io->bio; 569 int cpu; 570 int rw = bio_data_dir(bio); 571 572 io->start_time = jiffies; 573 574 cpu = part_stat_lock(); 575 part_round_stats(cpu, &dm_disk(md)->part0); 576 part_stat_unlock(); 577 atomic_set(&dm_disk(md)->part0.in_flight[rw], 578 atomic_inc_return(&md->pending[rw])); 579 580 if (unlikely(dm_stats_used(&md->stats))) 581 dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector, 582 bio_sectors(bio), false, 0, &io->stats_aux); 583 } 584 585 static void end_io_acct(struct dm_io *io) 586 { 587 struct mapped_device *md = io->md; 588 struct bio *bio = io->bio; 589 unsigned long duration = jiffies - io->start_time; 590 int pending, cpu; 591 int rw = bio_data_dir(bio); 592 593 cpu = part_stat_lock(); 594 part_round_stats(cpu, &dm_disk(md)->part0); 595 part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration); 596 part_stat_unlock(); 597 598 if (unlikely(dm_stats_used(&md->stats))) 599 dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector, 600 bio_sectors(bio), true, duration, &io->stats_aux); 601 602 /* 603 * After this is decremented the bio must not be touched if it is 604 * a flush. 605 */ 606 pending = atomic_dec_return(&md->pending[rw]); 607 atomic_set(&dm_disk(md)->part0.in_flight[rw], pending); 608 pending += atomic_read(&md->pending[rw^0x1]); 609 610 /* nudge anyone waiting on suspend queue */ 611 if (!pending) 612 wake_up(&md->wait); 613 } 614 615 /* 616 * Add the bio to the list of deferred io. 617 */ 618 static void queue_io(struct mapped_device *md, struct bio *bio) 619 { 620 unsigned long flags; 621 622 spin_lock_irqsave(&md->deferred_lock, flags); 623 bio_list_add(&md->deferred, bio); 624 spin_unlock_irqrestore(&md->deferred_lock, flags); 625 queue_work(md->wq, &md->work); 626 } 627 628 /* 629 * Everyone (including functions in this file), should use this 630 * function to access the md->map field, and make sure they call 631 * dm_put_live_table() when finished. 632 */ 633 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx) __acquires(md->io_barrier) 634 { 635 *srcu_idx = srcu_read_lock(&md->io_barrier); 636 637 return srcu_dereference(md->map, &md->io_barrier); 638 } 639 640 void dm_put_live_table(struct mapped_device *md, int srcu_idx) __releases(md->io_barrier) 641 { 642 srcu_read_unlock(&md->io_barrier, srcu_idx); 643 } 644 645 void dm_sync_table(struct mapped_device *md) 646 { 647 synchronize_srcu(&md->io_barrier); 648 synchronize_rcu_expedited(); 649 } 650 651 /* 652 * A fast alternative to dm_get_live_table/dm_put_live_table. 653 * The caller must not block between these two functions. 654 */ 655 static struct dm_table *dm_get_live_table_fast(struct mapped_device *md) __acquires(RCU) 656 { 657 rcu_read_lock(); 658 return rcu_dereference(md->map); 659 } 660 661 static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU) 662 { 663 rcu_read_unlock(); 664 } 665 666 /* 667 * Get the geometry associated with a dm device 668 */ 669 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo) 670 { 671 *geo = md->geometry; 672 673 return 0; 674 } 675 676 /* 677 * Set the geometry of a device. 678 */ 679 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo) 680 { 681 sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors; 682 683 if (geo->start > sz) { 684 DMWARN("Start sector is beyond the geometry limits."); 685 return -EINVAL; 686 } 687 688 md->geometry = *geo; 689 690 return 0; 691 } 692 693 /*----------------------------------------------------------------- 694 * CRUD START: 695 * A more elegant soln is in the works that uses the queue 696 * merge fn, unfortunately there are a couple of changes to 697 * the block layer that I want to make for this. So in the 698 * interests of getting something for people to use I give 699 * you this clearly demarcated crap. 700 *---------------------------------------------------------------*/ 701 702 static int __noflush_suspending(struct mapped_device *md) 703 { 704 return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 705 } 706 707 /* 708 * Decrements the number of outstanding ios that a bio has been 709 * cloned into, completing the original io if necc. 710 */ 711 static void dec_pending(struct dm_io *io, int error) 712 { 713 unsigned long flags; 714 int io_error; 715 struct bio *bio; 716 struct mapped_device *md = io->md; 717 718 /* Push-back supersedes any I/O errors */ 719 if (unlikely(error)) { 720 spin_lock_irqsave(&io->endio_lock, flags); 721 if (!(io->error > 0 && __noflush_suspending(md))) 722 io->error = error; 723 spin_unlock_irqrestore(&io->endio_lock, flags); 724 } 725 726 if (atomic_dec_and_test(&io->io_count)) { 727 if (io->error == DM_ENDIO_REQUEUE) { 728 /* 729 * Target requested pushing back the I/O. 730 */ 731 spin_lock_irqsave(&md->deferred_lock, flags); 732 if (__noflush_suspending(md)) 733 bio_list_add_head(&md->deferred, io->bio); 734 else 735 /* noflush suspend was interrupted. */ 736 io->error = -EIO; 737 spin_unlock_irqrestore(&md->deferred_lock, flags); 738 } 739 740 io_error = io->error; 741 bio = io->bio; 742 end_io_acct(io); 743 free_io(md, io); 744 745 if (io_error == DM_ENDIO_REQUEUE) 746 return; 747 748 if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) { 749 /* 750 * Preflush done for flush with data, reissue 751 * without REQ_FLUSH. 752 */ 753 bio->bi_rw &= ~REQ_FLUSH; 754 queue_io(md, bio); 755 } else { 756 /* done with normal IO or empty flush */ 757 trace_block_bio_complete(md->queue, bio, io_error); 758 bio_endio(bio, io_error); 759 } 760 } 761 } 762 763 static void clone_endio(struct bio *bio, int error) 764 { 765 int r = 0; 766 struct dm_target_io *tio = bio->bi_private; 767 struct dm_io *io = tio->io; 768 struct mapped_device *md = tio->io->md; 769 dm_endio_fn endio = tio->ti->type->end_io; 770 771 if (!bio_flagged(bio, BIO_UPTODATE) && !error) 772 error = -EIO; 773 774 if (endio) { 775 r = endio(tio->ti, bio, error); 776 if (r < 0 || r == DM_ENDIO_REQUEUE) 777 /* 778 * error and requeue request are handled 779 * in dec_pending(). 780 */ 781 error = r; 782 else if (r == DM_ENDIO_INCOMPLETE) 783 /* The target will handle the io */ 784 return; 785 else if (r) { 786 DMWARN("unimplemented target endio return value: %d", r); 787 BUG(); 788 } 789 } 790 791 free_tio(md, tio); 792 dec_pending(io, error); 793 } 794 795 /* 796 * Partial completion handling for request-based dm 797 */ 798 static void end_clone_bio(struct bio *clone, int error) 799 { 800 struct dm_rq_clone_bio_info *info = clone->bi_private; 801 struct dm_rq_target_io *tio = info->tio; 802 struct bio *bio = info->orig; 803 unsigned int nr_bytes = info->orig->bi_size; 804 805 bio_put(clone); 806 807 if (tio->error) 808 /* 809 * An error has already been detected on the request. 810 * Once error occurred, just let clone->end_io() handle 811 * the remainder. 812 */ 813 return; 814 else if (error) { 815 /* 816 * Don't notice the error to the upper layer yet. 817 * The error handling decision is made by the target driver, 818 * when the request is completed. 819 */ 820 tio->error = error; 821 return; 822 } 823 824 /* 825 * I/O for the bio successfully completed. 826 * Notice the data completion to the upper layer. 827 */ 828 829 /* 830 * bios are processed from the head of the list. 831 * So the completing bio should always be rq->bio. 832 * If it's not, something wrong is happening. 833 */ 834 if (tio->orig->bio != bio) 835 DMERR("bio completion is going in the middle of the request"); 836 837 /* 838 * Update the original request. 839 * Do not use blk_end_request() here, because it may complete 840 * the original request before the clone, and break the ordering. 841 */ 842 blk_update_request(tio->orig, 0, nr_bytes); 843 } 844 845 /* 846 * Don't touch any member of the md after calling this function because 847 * the md may be freed in dm_put() at the end of this function. 848 * Or do dm_get() before calling this function and dm_put() later. 849 */ 850 static void rq_completed(struct mapped_device *md, int rw, int run_queue) 851 { 852 atomic_dec(&md->pending[rw]); 853 854 /* nudge anyone waiting on suspend queue */ 855 if (!md_in_flight(md)) 856 wake_up(&md->wait); 857 858 /* 859 * Run this off this callpath, as drivers could invoke end_io while 860 * inside their request_fn (and holding the queue lock). Calling 861 * back into ->request_fn() could deadlock attempting to grab the 862 * queue lock again. 863 */ 864 if (run_queue) 865 blk_run_queue_async(md->queue); 866 867 /* 868 * dm_put() must be at the end of this function. See the comment above 869 */ 870 dm_put(md); 871 } 872 873 static void free_rq_clone(struct request *clone) 874 { 875 struct dm_rq_target_io *tio = clone->end_io_data; 876 877 blk_rq_unprep_clone(clone); 878 free_rq_tio(tio); 879 } 880 881 /* 882 * Complete the clone and the original request. 883 * Must be called without queue lock. 884 */ 885 static void dm_end_request(struct request *clone, int error) 886 { 887 int rw = rq_data_dir(clone); 888 struct dm_rq_target_io *tio = clone->end_io_data; 889 struct mapped_device *md = tio->md; 890 struct request *rq = tio->orig; 891 892 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { 893 rq->errors = clone->errors; 894 rq->resid_len = clone->resid_len; 895 896 if (rq->sense) 897 /* 898 * We are using the sense buffer of the original 899 * request. 900 * So setting the length of the sense data is enough. 901 */ 902 rq->sense_len = clone->sense_len; 903 } 904 905 free_rq_clone(clone); 906 blk_end_request_all(rq, error); 907 rq_completed(md, rw, true); 908 } 909 910 static void dm_unprep_request(struct request *rq) 911 { 912 struct request *clone = rq->special; 913 914 rq->special = NULL; 915 rq->cmd_flags &= ~REQ_DONTPREP; 916 917 free_rq_clone(clone); 918 } 919 920 /* 921 * Requeue the original request of a clone. 922 */ 923 void dm_requeue_unmapped_request(struct request *clone) 924 { 925 int rw = rq_data_dir(clone); 926 struct dm_rq_target_io *tio = clone->end_io_data; 927 struct mapped_device *md = tio->md; 928 struct request *rq = tio->orig; 929 struct request_queue *q = rq->q; 930 unsigned long flags; 931 932 dm_unprep_request(rq); 933 934 spin_lock_irqsave(q->queue_lock, flags); 935 blk_requeue_request(q, rq); 936 spin_unlock_irqrestore(q->queue_lock, flags); 937 938 rq_completed(md, rw, 0); 939 } 940 EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request); 941 942 static void __stop_queue(struct request_queue *q) 943 { 944 blk_stop_queue(q); 945 } 946 947 static void stop_queue(struct request_queue *q) 948 { 949 unsigned long flags; 950 951 spin_lock_irqsave(q->queue_lock, flags); 952 __stop_queue(q); 953 spin_unlock_irqrestore(q->queue_lock, flags); 954 } 955 956 static void __start_queue(struct request_queue *q) 957 { 958 if (blk_queue_stopped(q)) 959 blk_start_queue(q); 960 } 961 962 static void start_queue(struct request_queue *q) 963 { 964 unsigned long flags; 965 966 spin_lock_irqsave(q->queue_lock, flags); 967 __start_queue(q); 968 spin_unlock_irqrestore(q->queue_lock, flags); 969 } 970 971 static void dm_done(struct request *clone, int error, bool mapped) 972 { 973 int r = error; 974 struct dm_rq_target_io *tio = clone->end_io_data; 975 dm_request_endio_fn rq_end_io = NULL; 976 977 if (tio->ti) { 978 rq_end_io = tio->ti->type->rq_end_io; 979 980 if (mapped && rq_end_io) 981 r = rq_end_io(tio->ti, clone, error, &tio->info); 982 } 983 984 if (r <= 0) 985 /* The target wants to complete the I/O */ 986 dm_end_request(clone, r); 987 else if (r == DM_ENDIO_INCOMPLETE) 988 /* The target will handle the I/O */ 989 return; 990 else if (r == DM_ENDIO_REQUEUE) 991 /* The target wants to requeue the I/O */ 992 dm_requeue_unmapped_request(clone); 993 else { 994 DMWARN("unimplemented target endio return value: %d", r); 995 BUG(); 996 } 997 } 998 999 /* 1000 * Request completion handler for request-based dm 1001 */ 1002 static void dm_softirq_done(struct request *rq) 1003 { 1004 bool mapped = true; 1005 struct request *clone = rq->completion_data; 1006 struct dm_rq_target_io *tio = clone->end_io_data; 1007 1008 if (rq->cmd_flags & REQ_FAILED) 1009 mapped = false; 1010 1011 dm_done(clone, tio->error, mapped); 1012 } 1013 1014 /* 1015 * Complete the clone and the original request with the error status 1016 * through softirq context. 1017 */ 1018 static void dm_complete_request(struct request *clone, int error) 1019 { 1020 struct dm_rq_target_io *tio = clone->end_io_data; 1021 struct request *rq = tio->orig; 1022 1023 tio->error = error; 1024 rq->completion_data = clone; 1025 blk_complete_request(rq); 1026 } 1027 1028 /* 1029 * Complete the not-mapped clone and the original request with the error status 1030 * through softirq context. 1031 * Target's rq_end_io() function isn't called. 1032 * This may be used when the target's map_rq() function fails. 1033 */ 1034 void dm_kill_unmapped_request(struct request *clone, int error) 1035 { 1036 struct dm_rq_target_io *tio = clone->end_io_data; 1037 struct request *rq = tio->orig; 1038 1039 rq->cmd_flags |= REQ_FAILED; 1040 dm_complete_request(clone, error); 1041 } 1042 EXPORT_SYMBOL_GPL(dm_kill_unmapped_request); 1043 1044 /* 1045 * Called with the queue lock held 1046 */ 1047 static void end_clone_request(struct request *clone, int error) 1048 { 1049 /* 1050 * For just cleaning up the information of the queue in which 1051 * the clone was dispatched. 1052 * The clone is *NOT* freed actually here because it is alloced from 1053 * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags. 1054 */ 1055 __blk_put_request(clone->q, clone); 1056 1057 /* 1058 * Actual request completion is done in a softirq context which doesn't 1059 * hold the queue lock. Otherwise, deadlock could occur because: 1060 * - another request may be submitted by the upper level driver 1061 * of the stacking during the completion 1062 * - the submission which requires queue lock may be done 1063 * against this queue 1064 */ 1065 dm_complete_request(clone, error); 1066 } 1067 1068 /* 1069 * Return maximum size of I/O possible at the supplied sector up to the current 1070 * target boundary. 1071 */ 1072 static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti) 1073 { 1074 sector_t target_offset = dm_target_offset(ti, sector); 1075 1076 return ti->len - target_offset; 1077 } 1078 1079 static sector_t max_io_len(sector_t sector, struct dm_target *ti) 1080 { 1081 sector_t len = max_io_len_target_boundary(sector, ti); 1082 sector_t offset, max_len; 1083 1084 /* 1085 * Does the target need to split even further? 1086 */ 1087 if (ti->max_io_len) { 1088 offset = dm_target_offset(ti, sector); 1089 if (unlikely(ti->max_io_len & (ti->max_io_len - 1))) 1090 max_len = sector_div(offset, ti->max_io_len); 1091 else 1092 max_len = offset & (ti->max_io_len - 1); 1093 max_len = ti->max_io_len - max_len; 1094 1095 if (len > max_len) 1096 len = max_len; 1097 } 1098 1099 return len; 1100 } 1101 1102 int dm_set_target_max_io_len(struct dm_target *ti, sector_t len) 1103 { 1104 if (len > UINT_MAX) { 1105 DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)", 1106 (unsigned long long)len, UINT_MAX); 1107 ti->error = "Maximum size of target IO is too large"; 1108 return -EINVAL; 1109 } 1110 1111 ti->max_io_len = (uint32_t) len; 1112 1113 return 0; 1114 } 1115 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len); 1116 1117 static void __map_bio(struct dm_target_io *tio) 1118 { 1119 int r; 1120 sector_t sector; 1121 struct mapped_device *md; 1122 struct bio *clone = &tio->clone; 1123 struct dm_target *ti = tio->ti; 1124 1125 clone->bi_end_io = clone_endio; 1126 clone->bi_private = tio; 1127 1128 /* 1129 * Map the clone. If r == 0 we don't need to do 1130 * anything, the target has assumed ownership of 1131 * this io. 1132 */ 1133 atomic_inc(&tio->io->io_count); 1134 sector = clone->bi_sector; 1135 r = ti->type->map(ti, clone); 1136 if (r == DM_MAPIO_REMAPPED) { 1137 /* the bio has been remapped so dispatch it */ 1138 1139 trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone, 1140 tio->io->bio->bi_bdev->bd_dev, sector); 1141 1142 generic_make_request(clone); 1143 } else if (r < 0 || r == DM_MAPIO_REQUEUE) { 1144 /* error the io and bail out, or requeue it if needed */ 1145 md = tio->io->md; 1146 dec_pending(tio->io, r); 1147 free_tio(md, tio); 1148 } else if (r) { 1149 DMWARN("unimplemented target map return value: %d", r); 1150 BUG(); 1151 } 1152 } 1153 1154 struct clone_info { 1155 struct mapped_device *md; 1156 struct dm_table *map; 1157 struct bio *bio; 1158 struct dm_io *io; 1159 sector_t sector; 1160 sector_t sector_count; 1161 unsigned short idx; 1162 }; 1163 1164 static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len) 1165 { 1166 bio->bi_sector = sector; 1167 bio->bi_size = to_bytes(len); 1168 } 1169 1170 static void bio_setup_bv(struct bio *bio, unsigned short idx, unsigned short bv_count) 1171 { 1172 bio->bi_idx = idx; 1173 bio->bi_vcnt = idx + bv_count; 1174 bio->bi_flags &= ~(1 << BIO_SEG_VALID); 1175 } 1176 1177 static void clone_bio_integrity(struct bio *bio, struct bio *clone, 1178 unsigned short idx, unsigned len, unsigned offset, 1179 unsigned trim) 1180 { 1181 if (!bio_integrity(bio)) 1182 return; 1183 1184 bio_integrity_clone(clone, bio, GFP_NOIO); 1185 1186 if (trim) 1187 bio_integrity_trim(clone, bio_sector_offset(bio, idx, offset), len); 1188 } 1189 1190 /* 1191 * Creates a little bio that just does part of a bvec. 1192 */ 1193 static void clone_split_bio(struct dm_target_io *tio, struct bio *bio, 1194 sector_t sector, unsigned short idx, 1195 unsigned offset, unsigned len) 1196 { 1197 struct bio *clone = &tio->clone; 1198 struct bio_vec *bv = bio->bi_io_vec + idx; 1199 1200 *clone->bi_io_vec = *bv; 1201 1202 bio_setup_sector(clone, sector, len); 1203 1204 clone->bi_bdev = bio->bi_bdev; 1205 clone->bi_rw = bio->bi_rw; 1206 clone->bi_vcnt = 1; 1207 clone->bi_io_vec->bv_offset = offset; 1208 clone->bi_io_vec->bv_len = clone->bi_size; 1209 clone->bi_flags |= 1 << BIO_CLONED; 1210 1211 clone_bio_integrity(bio, clone, idx, len, offset, 1); 1212 } 1213 1214 /* 1215 * Creates a bio that consists of range of complete bvecs. 1216 */ 1217 static void clone_bio(struct dm_target_io *tio, struct bio *bio, 1218 sector_t sector, unsigned short idx, 1219 unsigned short bv_count, unsigned len) 1220 { 1221 struct bio *clone = &tio->clone; 1222 unsigned trim = 0; 1223 1224 __bio_clone(clone, bio); 1225 bio_setup_sector(clone, sector, len); 1226 bio_setup_bv(clone, idx, bv_count); 1227 1228 if (idx != bio->bi_idx || clone->bi_size < bio->bi_size) 1229 trim = 1; 1230 clone_bio_integrity(bio, clone, idx, len, 0, trim); 1231 } 1232 1233 static struct dm_target_io *alloc_tio(struct clone_info *ci, 1234 struct dm_target *ti, int nr_iovecs, 1235 unsigned target_bio_nr) 1236 { 1237 struct dm_target_io *tio; 1238 struct bio *clone; 1239 1240 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, ci->md->bs); 1241 tio = container_of(clone, struct dm_target_io, clone); 1242 1243 tio->io = ci->io; 1244 tio->ti = ti; 1245 memset(&tio->info, 0, sizeof(tio->info)); 1246 tio->target_bio_nr = target_bio_nr; 1247 1248 return tio; 1249 } 1250 1251 static void __clone_and_map_simple_bio(struct clone_info *ci, 1252 struct dm_target *ti, 1253 unsigned target_bio_nr, sector_t len) 1254 { 1255 struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr); 1256 struct bio *clone = &tio->clone; 1257 1258 /* 1259 * Discard requests require the bio's inline iovecs be initialized. 1260 * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush 1261 * and discard, so no need for concern about wasted bvec allocations. 1262 */ 1263 __bio_clone(clone, ci->bio); 1264 if (len) 1265 bio_setup_sector(clone, ci->sector, len); 1266 1267 __map_bio(tio); 1268 } 1269 1270 static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, 1271 unsigned num_bios, sector_t len) 1272 { 1273 unsigned target_bio_nr; 1274 1275 for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++) 1276 __clone_and_map_simple_bio(ci, ti, target_bio_nr, len); 1277 } 1278 1279 static int __send_empty_flush(struct clone_info *ci) 1280 { 1281 unsigned target_nr = 0; 1282 struct dm_target *ti; 1283 1284 BUG_ON(bio_has_data(ci->bio)); 1285 while ((ti = dm_table_get_target(ci->map, target_nr++))) 1286 __send_duplicate_bios(ci, ti, ti->num_flush_bios, 0); 1287 1288 return 0; 1289 } 1290 1291 static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti, 1292 sector_t sector, int nr_iovecs, 1293 unsigned short idx, unsigned short bv_count, 1294 unsigned offset, unsigned len, 1295 unsigned split_bvec) 1296 { 1297 struct bio *bio = ci->bio; 1298 struct dm_target_io *tio; 1299 unsigned target_bio_nr; 1300 unsigned num_target_bios = 1; 1301 1302 /* 1303 * Does the target want to receive duplicate copies of the bio? 1304 */ 1305 if (bio_data_dir(bio) == WRITE && ti->num_write_bios) 1306 num_target_bios = ti->num_write_bios(ti, bio); 1307 1308 for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) { 1309 tio = alloc_tio(ci, ti, nr_iovecs, target_bio_nr); 1310 if (split_bvec) 1311 clone_split_bio(tio, bio, sector, idx, offset, len); 1312 else 1313 clone_bio(tio, bio, sector, idx, bv_count, len); 1314 __map_bio(tio); 1315 } 1316 } 1317 1318 typedef unsigned (*get_num_bios_fn)(struct dm_target *ti); 1319 1320 static unsigned get_num_discard_bios(struct dm_target *ti) 1321 { 1322 return ti->num_discard_bios; 1323 } 1324 1325 static unsigned get_num_write_same_bios(struct dm_target *ti) 1326 { 1327 return ti->num_write_same_bios; 1328 } 1329 1330 typedef bool (*is_split_required_fn)(struct dm_target *ti); 1331 1332 static bool is_split_required_for_discard(struct dm_target *ti) 1333 { 1334 return ti->split_discard_bios; 1335 } 1336 1337 static int __send_changing_extent_only(struct clone_info *ci, 1338 get_num_bios_fn get_num_bios, 1339 is_split_required_fn is_split_required) 1340 { 1341 struct dm_target *ti; 1342 sector_t len; 1343 unsigned num_bios; 1344 1345 do { 1346 ti = dm_table_find_target(ci->map, ci->sector); 1347 if (!dm_target_is_valid(ti)) 1348 return -EIO; 1349 1350 /* 1351 * Even though the device advertised support for this type of 1352 * request, that does not mean every target supports it, and 1353 * reconfiguration might also have changed that since the 1354 * check was performed. 1355 */ 1356 num_bios = get_num_bios ? get_num_bios(ti) : 0; 1357 if (!num_bios) 1358 return -EOPNOTSUPP; 1359 1360 if (is_split_required && !is_split_required(ti)) 1361 len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti)); 1362 else 1363 len = min(ci->sector_count, max_io_len(ci->sector, ti)); 1364 1365 __send_duplicate_bios(ci, ti, num_bios, len); 1366 1367 ci->sector += len; 1368 } while (ci->sector_count -= len); 1369 1370 return 0; 1371 } 1372 1373 static int __send_discard(struct clone_info *ci) 1374 { 1375 return __send_changing_extent_only(ci, get_num_discard_bios, 1376 is_split_required_for_discard); 1377 } 1378 1379 static int __send_write_same(struct clone_info *ci) 1380 { 1381 return __send_changing_extent_only(ci, get_num_write_same_bios, NULL); 1382 } 1383 1384 /* 1385 * Find maximum number of sectors / bvecs we can process with a single bio. 1386 */ 1387 static sector_t __len_within_target(struct clone_info *ci, sector_t max, int *idx) 1388 { 1389 struct bio *bio = ci->bio; 1390 sector_t bv_len, total_len = 0; 1391 1392 for (*idx = ci->idx; max && (*idx < bio->bi_vcnt); (*idx)++) { 1393 bv_len = to_sector(bio->bi_io_vec[*idx].bv_len); 1394 1395 if (bv_len > max) 1396 break; 1397 1398 max -= bv_len; 1399 total_len += bv_len; 1400 } 1401 1402 return total_len; 1403 } 1404 1405 static int __split_bvec_across_targets(struct clone_info *ci, 1406 struct dm_target *ti, sector_t max) 1407 { 1408 struct bio *bio = ci->bio; 1409 struct bio_vec *bv = bio->bi_io_vec + ci->idx; 1410 sector_t remaining = to_sector(bv->bv_len); 1411 unsigned offset = 0; 1412 sector_t len; 1413 1414 do { 1415 if (offset) { 1416 ti = dm_table_find_target(ci->map, ci->sector); 1417 if (!dm_target_is_valid(ti)) 1418 return -EIO; 1419 1420 max = max_io_len(ci->sector, ti); 1421 } 1422 1423 len = min(remaining, max); 1424 1425 __clone_and_map_data_bio(ci, ti, ci->sector, 1, ci->idx, 0, 1426 bv->bv_offset + offset, len, 1); 1427 1428 ci->sector += len; 1429 ci->sector_count -= len; 1430 offset += to_bytes(len); 1431 } while (remaining -= len); 1432 1433 ci->idx++; 1434 1435 return 0; 1436 } 1437 1438 /* 1439 * Select the correct strategy for processing a non-flush bio. 1440 */ 1441 static int __split_and_process_non_flush(struct clone_info *ci) 1442 { 1443 struct bio *bio = ci->bio; 1444 struct dm_target *ti; 1445 sector_t len, max; 1446 int idx; 1447 1448 if (unlikely(bio->bi_rw & REQ_DISCARD)) 1449 return __send_discard(ci); 1450 else if (unlikely(bio->bi_rw & REQ_WRITE_SAME)) 1451 return __send_write_same(ci); 1452 1453 ti = dm_table_find_target(ci->map, ci->sector); 1454 if (!dm_target_is_valid(ti)) 1455 return -EIO; 1456 1457 max = max_io_len(ci->sector, ti); 1458 1459 /* 1460 * Optimise for the simple case where we can do all of 1461 * the remaining io with a single clone. 1462 */ 1463 if (ci->sector_count <= max) { 1464 __clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs, 1465 ci->idx, bio->bi_vcnt - ci->idx, 0, 1466 ci->sector_count, 0); 1467 ci->sector_count = 0; 1468 return 0; 1469 } 1470 1471 /* 1472 * There are some bvecs that don't span targets. 1473 * Do as many of these as possible. 1474 */ 1475 if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) { 1476 len = __len_within_target(ci, max, &idx); 1477 1478 __clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs, 1479 ci->idx, idx - ci->idx, 0, len, 0); 1480 1481 ci->sector += len; 1482 ci->sector_count -= len; 1483 ci->idx = idx; 1484 1485 return 0; 1486 } 1487 1488 /* 1489 * Handle a bvec that must be split between two or more targets. 1490 */ 1491 return __split_bvec_across_targets(ci, ti, max); 1492 } 1493 1494 /* 1495 * Entry point to split a bio into clones and submit them to the targets. 1496 */ 1497 static void __split_and_process_bio(struct mapped_device *md, 1498 struct dm_table *map, struct bio *bio) 1499 { 1500 struct clone_info ci; 1501 int error = 0; 1502 1503 if (unlikely(!map)) { 1504 bio_io_error(bio); 1505 return; 1506 } 1507 1508 ci.map = map; 1509 ci.md = md; 1510 ci.io = alloc_io(md); 1511 ci.io->error = 0; 1512 atomic_set(&ci.io->io_count, 1); 1513 ci.io->bio = bio; 1514 ci.io->md = md; 1515 spin_lock_init(&ci.io->endio_lock); 1516 ci.sector = bio->bi_sector; 1517 ci.idx = bio->bi_idx; 1518 1519 start_io_acct(ci.io); 1520 1521 if (bio->bi_rw & REQ_FLUSH) { 1522 ci.bio = &ci.md->flush_bio; 1523 ci.sector_count = 0; 1524 error = __send_empty_flush(&ci); 1525 /* dec_pending submits any data associated with flush */ 1526 } else { 1527 ci.bio = bio; 1528 ci.sector_count = bio_sectors(bio); 1529 while (ci.sector_count && !error) 1530 error = __split_and_process_non_flush(&ci); 1531 } 1532 1533 /* drop the extra reference count */ 1534 dec_pending(ci.io, error); 1535 } 1536 /*----------------------------------------------------------------- 1537 * CRUD END 1538 *---------------------------------------------------------------*/ 1539 1540 static int dm_merge_bvec(struct request_queue *q, 1541 struct bvec_merge_data *bvm, 1542 struct bio_vec *biovec) 1543 { 1544 struct mapped_device *md = q->queuedata; 1545 struct dm_table *map = dm_get_live_table_fast(md); 1546 struct dm_target *ti; 1547 sector_t max_sectors; 1548 int max_size = 0; 1549 1550 if (unlikely(!map)) 1551 goto out; 1552 1553 ti = dm_table_find_target(map, bvm->bi_sector); 1554 if (!dm_target_is_valid(ti)) 1555 goto out; 1556 1557 /* 1558 * Find maximum amount of I/O that won't need splitting 1559 */ 1560 max_sectors = min(max_io_len(bvm->bi_sector, ti), 1561 (sector_t) BIO_MAX_SECTORS); 1562 max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size; 1563 if (max_size < 0) 1564 max_size = 0; 1565 1566 /* 1567 * merge_bvec_fn() returns number of bytes 1568 * it can accept at this offset 1569 * max is precomputed maximal io size 1570 */ 1571 if (max_size && ti->type->merge) 1572 max_size = ti->type->merge(ti, bvm, biovec, max_size); 1573 /* 1574 * If the target doesn't support merge method and some of the devices 1575 * provided their merge_bvec method (we know this by looking at 1576 * queue_max_hw_sectors), then we can't allow bios with multiple vector 1577 * entries. So always set max_size to 0, and the code below allows 1578 * just one page. 1579 */ 1580 else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9) 1581 1582 max_size = 0; 1583 1584 out: 1585 dm_put_live_table_fast(md); 1586 /* 1587 * Always allow an entire first page 1588 */ 1589 if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT)) 1590 max_size = biovec->bv_len; 1591 1592 return max_size; 1593 } 1594 1595 /* 1596 * The request function that just remaps the bio built up by 1597 * dm_merge_bvec. 1598 */ 1599 static void _dm_request(struct request_queue *q, struct bio *bio) 1600 { 1601 int rw = bio_data_dir(bio); 1602 struct mapped_device *md = q->queuedata; 1603 int cpu; 1604 int srcu_idx; 1605 struct dm_table *map; 1606 1607 map = dm_get_live_table(md, &srcu_idx); 1608 1609 cpu = part_stat_lock(); 1610 part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]); 1611 part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio)); 1612 part_stat_unlock(); 1613 1614 /* if we're suspended, we have to queue this io for later */ 1615 if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) { 1616 dm_put_live_table(md, srcu_idx); 1617 1618 if (bio_rw(bio) != READA) 1619 queue_io(md, bio); 1620 else 1621 bio_io_error(bio); 1622 return; 1623 } 1624 1625 __split_and_process_bio(md, map, bio); 1626 dm_put_live_table(md, srcu_idx); 1627 return; 1628 } 1629 1630 int dm_request_based(struct mapped_device *md) 1631 { 1632 return blk_queue_stackable(md->queue); 1633 } 1634 1635 static void dm_request(struct request_queue *q, struct bio *bio) 1636 { 1637 struct mapped_device *md = q->queuedata; 1638 1639 if (dm_request_based(md)) 1640 blk_queue_bio(q, bio); 1641 else 1642 _dm_request(q, bio); 1643 } 1644 1645 void dm_dispatch_request(struct request *rq) 1646 { 1647 int r; 1648 1649 if (blk_queue_io_stat(rq->q)) 1650 rq->cmd_flags |= REQ_IO_STAT; 1651 1652 rq->start_time = jiffies; 1653 r = blk_insert_cloned_request(rq->q, rq); 1654 if (r) 1655 dm_complete_request(rq, r); 1656 } 1657 EXPORT_SYMBOL_GPL(dm_dispatch_request); 1658 1659 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig, 1660 void *data) 1661 { 1662 struct dm_rq_target_io *tio = data; 1663 struct dm_rq_clone_bio_info *info = 1664 container_of(bio, struct dm_rq_clone_bio_info, clone); 1665 1666 info->orig = bio_orig; 1667 info->tio = tio; 1668 bio->bi_end_io = end_clone_bio; 1669 bio->bi_private = info; 1670 1671 return 0; 1672 } 1673 1674 static int setup_clone(struct request *clone, struct request *rq, 1675 struct dm_rq_target_io *tio) 1676 { 1677 int r; 1678 1679 r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC, 1680 dm_rq_bio_constructor, tio); 1681 if (r) 1682 return r; 1683 1684 clone->cmd = rq->cmd; 1685 clone->cmd_len = rq->cmd_len; 1686 clone->sense = rq->sense; 1687 clone->buffer = rq->buffer; 1688 clone->end_io = end_clone_request; 1689 clone->end_io_data = tio; 1690 1691 return 0; 1692 } 1693 1694 static struct request *clone_rq(struct request *rq, struct mapped_device *md, 1695 gfp_t gfp_mask) 1696 { 1697 struct request *clone; 1698 struct dm_rq_target_io *tio; 1699 1700 tio = alloc_rq_tio(md, gfp_mask); 1701 if (!tio) 1702 return NULL; 1703 1704 tio->md = md; 1705 tio->ti = NULL; 1706 tio->orig = rq; 1707 tio->error = 0; 1708 memset(&tio->info, 0, sizeof(tio->info)); 1709 1710 clone = &tio->clone; 1711 if (setup_clone(clone, rq, tio)) { 1712 /* -ENOMEM */ 1713 free_rq_tio(tio); 1714 return NULL; 1715 } 1716 1717 return clone; 1718 } 1719 1720 /* 1721 * Called with the queue lock held. 1722 */ 1723 static int dm_prep_fn(struct request_queue *q, struct request *rq) 1724 { 1725 struct mapped_device *md = q->queuedata; 1726 struct request *clone; 1727 1728 if (unlikely(rq->special)) { 1729 DMWARN("Already has something in rq->special."); 1730 return BLKPREP_KILL; 1731 } 1732 1733 clone = clone_rq(rq, md, GFP_ATOMIC); 1734 if (!clone) 1735 return BLKPREP_DEFER; 1736 1737 rq->special = clone; 1738 rq->cmd_flags |= REQ_DONTPREP; 1739 1740 return BLKPREP_OK; 1741 } 1742 1743 /* 1744 * Returns: 1745 * 0 : the request has been processed (not requeued) 1746 * !0 : the request has been requeued 1747 */ 1748 static int map_request(struct dm_target *ti, struct request *clone, 1749 struct mapped_device *md) 1750 { 1751 int r, requeued = 0; 1752 struct dm_rq_target_io *tio = clone->end_io_data; 1753 1754 tio->ti = ti; 1755 r = ti->type->map_rq(ti, clone, &tio->info); 1756 switch (r) { 1757 case DM_MAPIO_SUBMITTED: 1758 /* The target has taken the I/O to submit by itself later */ 1759 break; 1760 case DM_MAPIO_REMAPPED: 1761 /* The target has remapped the I/O so dispatch it */ 1762 trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)), 1763 blk_rq_pos(tio->orig)); 1764 dm_dispatch_request(clone); 1765 break; 1766 case DM_MAPIO_REQUEUE: 1767 /* The target wants to requeue the I/O */ 1768 dm_requeue_unmapped_request(clone); 1769 requeued = 1; 1770 break; 1771 default: 1772 if (r > 0) { 1773 DMWARN("unimplemented target map return value: %d", r); 1774 BUG(); 1775 } 1776 1777 /* The target wants to complete the I/O */ 1778 dm_kill_unmapped_request(clone, r); 1779 break; 1780 } 1781 1782 return requeued; 1783 } 1784 1785 static struct request *dm_start_request(struct mapped_device *md, struct request *orig) 1786 { 1787 struct request *clone; 1788 1789 blk_start_request(orig); 1790 clone = orig->special; 1791 atomic_inc(&md->pending[rq_data_dir(clone)]); 1792 1793 /* 1794 * Hold the md reference here for the in-flight I/O. 1795 * We can't rely on the reference count by device opener, 1796 * because the device may be closed during the request completion 1797 * when all bios are completed. 1798 * See the comment in rq_completed() too. 1799 */ 1800 dm_get(md); 1801 1802 return clone; 1803 } 1804 1805 /* 1806 * q->request_fn for request-based dm. 1807 * Called with the queue lock held. 1808 */ 1809 static void dm_request_fn(struct request_queue *q) 1810 { 1811 struct mapped_device *md = q->queuedata; 1812 int srcu_idx; 1813 struct dm_table *map = dm_get_live_table(md, &srcu_idx); 1814 struct dm_target *ti; 1815 struct request *rq, *clone; 1816 sector_t pos; 1817 1818 /* 1819 * For suspend, check blk_queue_stopped() and increment 1820 * ->pending within a single queue_lock not to increment the 1821 * number of in-flight I/Os after the queue is stopped in 1822 * dm_suspend(). 1823 */ 1824 while (!blk_queue_stopped(q)) { 1825 rq = blk_peek_request(q); 1826 if (!rq) 1827 goto delay_and_out; 1828 1829 /* always use block 0 to find the target for flushes for now */ 1830 pos = 0; 1831 if (!(rq->cmd_flags & REQ_FLUSH)) 1832 pos = blk_rq_pos(rq); 1833 1834 ti = dm_table_find_target(map, pos); 1835 if (!dm_target_is_valid(ti)) { 1836 /* 1837 * Must perform setup, that dm_done() requires, 1838 * before calling dm_kill_unmapped_request 1839 */ 1840 DMERR_LIMIT("request attempted access beyond the end of device"); 1841 clone = dm_start_request(md, rq); 1842 dm_kill_unmapped_request(clone, -EIO); 1843 continue; 1844 } 1845 1846 if (ti->type->busy && ti->type->busy(ti)) 1847 goto delay_and_out; 1848 1849 clone = dm_start_request(md, rq); 1850 1851 spin_unlock(q->queue_lock); 1852 if (map_request(ti, clone, md)) 1853 goto requeued; 1854 1855 BUG_ON(!irqs_disabled()); 1856 spin_lock(q->queue_lock); 1857 } 1858 1859 goto out; 1860 1861 requeued: 1862 BUG_ON(!irqs_disabled()); 1863 spin_lock(q->queue_lock); 1864 1865 delay_and_out: 1866 blk_delay_queue(q, HZ / 10); 1867 out: 1868 dm_put_live_table(md, srcu_idx); 1869 } 1870 1871 int dm_underlying_device_busy(struct request_queue *q) 1872 { 1873 return blk_lld_busy(q); 1874 } 1875 EXPORT_SYMBOL_GPL(dm_underlying_device_busy); 1876 1877 static int dm_lld_busy(struct request_queue *q) 1878 { 1879 int r; 1880 struct mapped_device *md = q->queuedata; 1881 struct dm_table *map = dm_get_live_table_fast(md); 1882 1883 if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) 1884 r = 1; 1885 else 1886 r = dm_table_any_busy_target(map); 1887 1888 dm_put_live_table_fast(md); 1889 1890 return r; 1891 } 1892 1893 static int dm_any_congested(void *congested_data, int bdi_bits) 1894 { 1895 int r = bdi_bits; 1896 struct mapped_device *md = congested_data; 1897 struct dm_table *map; 1898 1899 if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) { 1900 map = dm_get_live_table_fast(md); 1901 if (map) { 1902 /* 1903 * Request-based dm cares about only own queue for 1904 * the query about congestion status of request_queue 1905 */ 1906 if (dm_request_based(md)) 1907 r = md->queue->backing_dev_info.state & 1908 bdi_bits; 1909 else 1910 r = dm_table_any_congested(map, bdi_bits); 1911 } 1912 dm_put_live_table_fast(md); 1913 } 1914 1915 return r; 1916 } 1917 1918 /*----------------------------------------------------------------- 1919 * An IDR is used to keep track of allocated minor numbers. 1920 *---------------------------------------------------------------*/ 1921 static void free_minor(int minor) 1922 { 1923 spin_lock(&_minor_lock); 1924 idr_remove(&_minor_idr, minor); 1925 spin_unlock(&_minor_lock); 1926 } 1927 1928 /* 1929 * See if the device with a specific minor # is free. 1930 */ 1931 static int specific_minor(int minor) 1932 { 1933 int r; 1934 1935 if (minor >= (1 << MINORBITS)) 1936 return -EINVAL; 1937 1938 idr_preload(GFP_KERNEL); 1939 spin_lock(&_minor_lock); 1940 1941 r = idr_alloc(&_minor_idr, MINOR_ALLOCED, minor, minor + 1, GFP_NOWAIT); 1942 1943 spin_unlock(&_minor_lock); 1944 idr_preload_end(); 1945 if (r < 0) 1946 return r == -ENOSPC ? -EBUSY : r; 1947 return 0; 1948 } 1949 1950 static int next_free_minor(int *minor) 1951 { 1952 int r; 1953 1954 idr_preload(GFP_KERNEL); 1955 spin_lock(&_minor_lock); 1956 1957 r = idr_alloc(&_minor_idr, MINOR_ALLOCED, 0, 1 << MINORBITS, GFP_NOWAIT); 1958 1959 spin_unlock(&_minor_lock); 1960 idr_preload_end(); 1961 if (r < 0) 1962 return r; 1963 *minor = r; 1964 return 0; 1965 } 1966 1967 static const struct block_device_operations dm_blk_dops; 1968 1969 static void dm_wq_work(struct work_struct *work); 1970 1971 static void dm_init_md_queue(struct mapped_device *md) 1972 { 1973 /* 1974 * Request-based dm devices cannot be stacked on top of bio-based dm 1975 * devices. The type of this dm device has not been decided yet. 1976 * The type is decided at the first table loading time. 1977 * To prevent problematic device stacking, clear the queue flag 1978 * for request stacking support until then. 1979 * 1980 * This queue is new, so no concurrency on the queue_flags. 1981 */ 1982 queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue); 1983 1984 md->queue->queuedata = md; 1985 md->queue->backing_dev_info.congested_fn = dm_any_congested; 1986 md->queue->backing_dev_info.congested_data = md; 1987 blk_queue_make_request(md->queue, dm_request); 1988 blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); 1989 blk_queue_merge_bvec(md->queue, dm_merge_bvec); 1990 } 1991 1992 /* 1993 * Allocate and initialise a blank device with a given minor. 1994 */ 1995 static struct mapped_device *alloc_dev(int minor) 1996 { 1997 int r; 1998 struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL); 1999 void *old_md; 2000 2001 if (!md) { 2002 DMWARN("unable to allocate device, out of memory."); 2003 return NULL; 2004 } 2005 2006 if (!try_module_get(THIS_MODULE)) 2007 goto bad_module_get; 2008 2009 /* get a minor number for the dev */ 2010 if (minor == DM_ANY_MINOR) 2011 r = next_free_minor(&minor); 2012 else 2013 r = specific_minor(minor); 2014 if (r < 0) 2015 goto bad_minor; 2016 2017 r = init_srcu_struct(&md->io_barrier); 2018 if (r < 0) 2019 goto bad_io_barrier; 2020 2021 md->type = DM_TYPE_NONE; 2022 mutex_init(&md->suspend_lock); 2023 mutex_init(&md->type_lock); 2024 spin_lock_init(&md->deferred_lock); 2025 atomic_set(&md->holders, 1); 2026 atomic_set(&md->open_count, 0); 2027 atomic_set(&md->event_nr, 0); 2028 atomic_set(&md->uevent_seq, 0); 2029 INIT_LIST_HEAD(&md->uevent_list); 2030 spin_lock_init(&md->uevent_lock); 2031 2032 md->queue = blk_alloc_queue(GFP_KERNEL); 2033 if (!md->queue) 2034 goto bad_queue; 2035 2036 dm_init_md_queue(md); 2037 2038 md->disk = alloc_disk(1); 2039 if (!md->disk) 2040 goto bad_disk; 2041 2042 atomic_set(&md->pending[0], 0); 2043 atomic_set(&md->pending[1], 0); 2044 init_waitqueue_head(&md->wait); 2045 INIT_WORK(&md->work, dm_wq_work); 2046 init_waitqueue_head(&md->eventq); 2047 init_completion(&md->kobj_completion); 2048 2049 md->disk->major = _major; 2050 md->disk->first_minor = minor; 2051 md->disk->fops = &dm_blk_dops; 2052 md->disk->queue = md->queue; 2053 md->disk->private_data = md; 2054 sprintf(md->disk->disk_name, "dm-%d", minor); 2055 add_disk(md->disk); 2056 format_dev_t(md->name, MKDEV(_major, minor)); 2057 2058 md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0); 2059 if (!md->wq) 2060 goto bad_thread; 2061 2062 md->bdev = bdget_disk(md->disk, 0); 2063 if (!md->bdev) 2064 goto bad_bdev; 2065 2066 bio_init(&md->flush_bio); 2067 md->flush_bio.bi_bdev = md->bdev; 2068 md->flush_bio.bi_rw = WRITE_FLUSH; 2069 2070 dm_stats_init(&md->stats); 2071 2072 /* Populate the mapping, nobody knows we exist yet */ 2073 spin_lock(&_minor_lock); 2074 old_md = idr_replace(&_minor_idr, md, minor); 2075 spin_unlock(&_minor_lock); 2076 2077 BUG_ON(old_md != MINOR_ALLOCED); 2078 2079 return md; 2080 2081 bad_bdev: 2082 destroy_workqueue(md->wq); 2083 bad_thread: 2084 del_gendisk(md->disk); 2085 put_disk(md->disk); 2086 bad_disk: 2087 blk_cleanup_queue(md->queue); 2088 bad_queue: 2089 cleanup_srcu_struct(&md->io_barrier); 2090 bad_io_barrier: 2091 free_minor(minor); 2092 bad_minor: 2093 module_put(THIS_MODULE); 2094 bad_module_get: 2095 kfree(md); 2096 return NULL; 2097 } 2098 2099 static void unlock_fs(struct mapped_device *md); 2100 2101 static void free_dev(struct mapped_device *md) 2102 { 2103 int minor = MINOR(disk_devt(md->disk)); 2104 2105 unlock_fs(md); 2106 bdput(md->bdev); 2107 destroy_workqueue(md->wq); 2108 if (md->io_pool) 2109 mempool_destroy(md->io_pool); 2110 if (md->bs) 2111 bioset_free(md->bs); 2112 blk_integrity_unregister(md->disk); 2113 del_gendisk(md->disk); 2114 cleanup_srcu_struct(&md->io_barrier); 2115 free_minor(minor); 2116 2117 spin_lock(&_minor_lock); 2118 md->disk->private_data = NULL; 2119 spin_unlock(&_minor_lock); 2120 2121 put_disk(md->disk); 2122 blk_cleanup_queue(md->queue); 2123 dm_stats_cleanup(&md->stats); 2124 module_put(THIS_MODULE); 2125 kfree(md); 2126 } 2127 2128 static void __bind_mempools(struct mapped_device *md, struct dm_table *t) 2129 { 2130 struct dm_md_mempools *p = dm_table_get_md_mempools(t); 2131 2132 if (md->io_pool && md->bs) { 2133 /* The md already has necessary mempools. */ 2134 if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) { 2135 /* 2136 * Reload bioset because front_pad may have changed 2137 * because a different table was loaded. 2138 */ 2139 bioset_free(md->bs); 2140 md->bs = p->bs; 2141 p->bs = NULL; 2142 } else if (dm_table_get_type(t) == DM_TYPE_REQUEST_BASED) { 2143 /* 2144 * There's no need to reload with request-based dm 2145 * because the size of front_pad doesn't change. 2146 * Note for future: If you are to reload bioset, 2147 * prep-ed requests in the queue may refer 2148 * to bio from the old bioset, so you must walk 2149 * through the queue to unprep. 2150 */ 2151 } 2152 goto out; 2153 } 2154 2155 BUG_ON(!p || md->io_pool || md->bs); 2156 2157 md->io_pool = p->io_pool; 2158 p->io_pool = NULL; 2159 md->bs = p->bs; 2160 p->bs = NULL; 2161 2162 out: 2163 /* mempool bind completed, now no need any mempools in the table */ 2164 dm_table_free_md_mempools(t); 2165 } 2166 2167 /* 2168 * Bind a table to the device. 2169 */ 2170 static void event_callback(void *context) 2171 { 2172 unsigned long flags; 2173 LIST_HEAD(uevents); 2174 struct mapped_device *md = (struct mapped_device *) context; 2175 2176 spin_lock_irqsave(&md->uevent_lock, flags); 2177 list_splice_init(&md->uevent_list, &uevents); 2178 spin_unlock_irqrestore(&md->uevent_lock, flags); 2179 2180 dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj); 2181 2182 atomic_inc(&md->event_nr); 2183 wake_up(&md->eventq); 2184 } 2185 2186 /* 2187 * Protected by md->suspend_lock obtained by dm_swap_table(). 2188 */ 2189 static void __set_size(struct mapped_device *md, sector_t size) 2190 { 2191 set_capacity(md->disk, size); 2192 2193 i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); 2194 } 2195 2196 /* 2197 * Return 1 if the queue has a compulsory merge_bvec_fn function. 2198 * 2199 * If this function returns 0, then the device is either a non-dm 2200 * device without a merge_bvec_fn, or it is a dm device that is 2201 * able to split any bios it receives that are too big. 2202 */ 2203 int dm_queue_merge_is_compulsory(struct request_queue *q) 2204 { 2205 struct mapped_device *dev_md; 2206 2207 if (!q->merge_bvec_fn) 2208 return 0; 2209 2210 if (q->make_request_fn == dm_request) { 2211 dev_md = q->queuedata; 2212 if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags)) 2213 return 0; 2214 } 2215 2216 return 1; 2217 } 2218 2219 static int dm_device_merge_is_compulsory(struct dm_target *ti, 2220 struct dm_dev *dev, sector_t start, 2221 sector_t len, void *data) 2222 { 2223 struct block_device *bdev = dev->bdev; 2224 struct request_queue *q = bdev_get_queue(bdev); 2225 2226 return dm_queue_merge_is_compulsory(q); 2227 } 2228 2229 /* 2230 * Return 1 if it is acceptable to ignore merge_bvec_fn based 2231 * on the properties of the underlying devices. 2232 */ 2233 static int dm_table_merge_is_optional(struct dm_table *table) 2234 { 2235 unsigned i = 0; 2236 struct dm_target *ti; 2237 2238 while (i < dm_table_get_num_targets(table)) { 2239 ti = dm_table_get_target(table, i++); 2240 2241 if (ti->type->iterate_devices && 2242 ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL)) 2243 return 0; 2244 } 2245 2246 return 1; 2247 } 2248 2249 /* 2250 * Returns old map, which caller must destroy. 2251 */ 2252 static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, 2253 struct queue_limits *limits) 2254 { 2255 struct dm_table *old_map; 2256 struct request_queue *q = md->queue; 2257 sector_t size; 2258 int merge_is_optional; 2259 2260 size = dm_table_get_size(t); 2261 2262 /* 2263 * Wipe any geometry if the size of the table changed. 2264 */ 2265 if (size != dm_get_size(md)) 2266 memset(&md->geometry, 0, sizeof(md->geometry)); 2267 2268 __set_size(md, size); 2269 2270 dm_table_event_callback(t, event_callback, md); 2271 2272 /* 2273 * The queue hasn't been stopped yet, if the old table type wasn't 2274 * for request-based during suspension. So stop it to prevent 2275 * I/O mapping before resume. 2276 * This must be done before setting the queue restrictions, 2277 * because request-based dm may be run just after the setting. 2278 */ 2279 if (dm_table_request_based(t) && !blk_queue_stopped(q)) 2280 stop_queue(q); 2281 2282 __bind_mempools(md, t); 2283 2284 merge_is_optional = dm_table_merge_is_optional(t); 2285 2286 old_map = md->map; 2287 rcu_assign_pointer(md->map, t); 2288 md->immutable_target_type = dm_table_get_immutable_target_type(t); 2289 2290 dm_table_set_restrictions(t, q, limits); 2291 if (merge_is_optional) 2292 set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags); 2293 else 2294 clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags); 2295 dm_sync_table(md); 2296 2297 return old_map; 2298 } 2299 2300 /* 2301 * Returns unbound table for the caller to free. 2302 */ 2303 static struct dm_table *__unbind(struct mapped_device *md) 2304 { 2305 struct dm_table *map = md->map; 2306 2307 if (!map) 2308 return NULL; 2309 2310 dm_table_event_callback(map, NULL, NULL); 2311 rcu_assign_pointer(md->map, NULL); 2312 dm_sync_table(md); 2313 2314 return map; 2315 } 2316 2317 /* 2318 * Constructor for a new device. 2319 */ 2320 int dm_create(int minor, struct mapped_device **result) 2321 { 2322 struct mapped_device *md; 2323 2324 md = alloc_dev(minor); 2325 if (!md) 2326 return -ENXIO; 2327 2328 dm_sysfs_init(md); 2329 2330 *result = md; 2331 return 0; 2332 } 2333 2334 /* 2335 * Functions to manage md->type. 2336 * All are required to hold md->type_lock. 2337 */ 2338 void dm_lock_md_type(struct mapped_device *md) 2339 { 2340 mutex_lock(&md->type_lock); 2341 } 2342 2343 void dm_unlock_md_type(struct mapped_device *md) 2344 { 2345 mutex_unlock(&md->type_lock); 2346 } 2347 2348 void dm_set_md_type(struct mapped_device *md, unsigned type) 2349 { 2350 BUG_ON(!mutex_is_locked(&md->type_lock)); 2351 md->type = type; 2352 } 2353 2354 unsigned dm_get_md_type(struct mapped_device *md) 2355 { 2356 BUG_ON(!mutex_is_locked(&md->type_lock)); 2357 return md->type; 2358 } 2359 2360 struct target_type *dm_get_immutable_target_type(struct mapped_device *md) 2361 { 2362 return md->immutable_target_type; 2363 } 2364 2365 /* 2366 * The queue_limits are only valid as long as you have a reference 2367 * count on 'md'. 2368 */ 2369 struct queue_limits *dm_get_queue_limits(struct mapped_device *md) 2370 { 2371 BUG_ON(!atomic_read(&md->holders)); 2372 return &md->queue->limits; 2373 } 2374 EXPORT_SYMBOL_GPL(dm_get_queue_limits); 2375 2376 /* 2377 * Fully initialize a request-based queue (->elevator, ->request_fn, etc). 2378 */ 2379 static int dm_init_request_based_queue(struct mapped_device *md) 2380 { 2381 struct request_queue *q = NULL; 2382 2383 if (md->queue->elevator) 2384 return 1; 2385 2386 /* Fully initialize the queue */ 2387 q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL); 2388 if (!q) 2389 return 0; 2390 2391 md->queue = q; 2392 dm_init_md_queue(md); 2393 blk_queue_softirq_done(md->queue, dm_softirq_done); 2394 blk_queue_prep_rq(md->queue, dm_prep_fn); 2395 blk_queue_lld_busy(md->queue, dm_lld_busy); 2396 2397 elv_register_queue(md->queue); 2398 2399 return 1; 2400 } 2401 2402 /* 2403 * Setup the DM device's queue based on md's type 2404 */ 2405 int dm_setup_md_queue(struct mapped_device *md) 2406 { 2407 if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) && 2408 !dm_init_request_based_queue(md)) { 2409 DMWARN("Cannot initialize queue for request-based mapped device"); 2410 return -EINVAL; 2411 } 2412 2413 return 0; 2414 } 2415 2416 static struct mapped_device *dm_find_md(dev_t dev) 2417 { 2418 struct mapped_device *md; 2419 unsigned minor = MINOR(dev); 2420 2421 if (MAJOR(dev) != _major || minor >= (1 << MINORBITS)) 2422 return NULL; 2423 2424 spin_lock(&_minor_lock); 2425 2426 md = idr_find(&_minor_idr, minor); 2427 if (md && (md == MINOR_ALLOCED || 2428 (MINOR(disk_devt(dm_disk(md))) != minor) || 2429 dm_deleting_md(md) || 2430 test_bit(DMF_FREEING, &md->flags))) { 2431 md = NULL; 2432 goto out; 2433 } 2434 2435 out: 2436 spin_unlock(&_minor_lock); 2437 2438 return md; 2439 } 2440 2441 struct mapped_device *dm_get_md(dev_t dev) 2442 { 2443 struct mapped_device *md = dm_find_md(dev); 2444 2445 if (md) 2446 dm_get(md); 2447 2448 return md; 2449 } 2450 EXPORT_SYMBOL_GPL(dm_get_md); 2451 2452 void *dm_get_mdptr(struct mapped_device *md) 2453 { 2454 return md->interface_ptr; 2455 } 2456 2457 void dm_set_mdptr(struct mapped_device *md, void *ptr) 2458 { 2459 md->interface_ptr = ptr; 2460 } 2461 2462 void dm_get(struct mapped_device *md) 2463 { 2464 atomic_inc(&md->holders); 2465 BUG_ON(test_bit(DMF_FREEING, &md->flags)); 2466 } 2467 2468 const char *dm_device_name(struct mapped_device *md) 2469 { 2470 return md->name; 2471 } 2472 EXPORT_SYMBOL_GPL(dm_device_name); 2473 2474 static void __dm_destroy(struct mapped_device *md, bool wait) 2475 { 2476 struct dm_table *map; 2477 int srcu_idx; 2478 2479 might_sleep(); 2480 2481 spin_lock(&_minor_lock); 2482 map = dm_get_live_table(md, &srcu_idx); 2483 idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md)))); 2484 set_bit(DMF_FREEING, &md->flags); 2485 spin_unlock(&_minor_lock); 2486 2487 if (!dm_suspended_md(md)) { 2488 dm_table_presuspend_targets(map); 2489 dm_table_postsuspend_targets(map); 2490 } 2491 2492 /* dm_put_live_table must be before msleep, otherwise deadlock is possible */ 2493 dm_put_live_table(md, srcu_idx); 2494 2495 /* 2496 * Rare, but there may be I/O requests still going to complete, 2497 * for example. Wait for all references to disappear. 2498 * No one should increment the reference count of the mapped_device, 2499 * after the mapped_device state becomes DMF_FREEING. 2500 */ 2501 if (wait) 2502 while (atomic_read(&md->holders)) 2503 msleep(1); 2504 else if (atomic_read(&md->holders)) 2505 DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)", 2506 dm_device_name(md), atomic_read(&md->holders)); 2507 2508 dm_sysfs_exit(md); 2509 dm_table_destroy(__unbind(md)); 2510 free_dev(md); 2511 } 2512 2513 void dm_destroy(struct mapped_device *md) 2514 { 2515 __dm_destroy(md, true); 2516 } 2517 2518 void dm_destroy_immediate(struct mapped_device *md) 2519 { 2520 __dm_destroy(md, false); 2521 } 2522 2523 void dm_put(struct mapped_device *md) 2524 { 2525 atomic_dec(&md->holders); 2526 } 2527 EXPORT_SYMBOL_GPL(dm_put); 2528 2529 static int dm_wait_for_completion(struct mapped_device *md, int interruptible) 2530 { 2531 int r = 0; 2532 DECLARE_WAITQUEUE(wait, current); 2533 2534 add_wait_queue(&md->wait, &wait); 2535 2536 while (1) { 2537 set_current_state(interruptible); 2538 2539 if (!md_in_flight(md)) 2540 break; 2541 2542 if (interruptible == TASK_INTERRUPTIBLE && 2543 signal_pending(current)) { 2544 r = -EINTR; 2545 break; 2546 } 2547 2548 io_schedule(); 2549 } 2550 set_current_state(TASK_RUNNING); 2551 2552 remove_wait_queue(&md->wait, &wait); 2553 2554 return r; 2555 } 2556 2557 /* 2558 * Process the deferred bios 2559 */ 2560 static void dm_wq_work(struct work_struct *work) 2561 { 2562 struct mapped_device *md = container_of(work, struct mapped_device, 2563 work); 2564 struct bio *c; 2565 int srcu_idx; 2566 struct dm_table *map; 2567 2568 map = dm_get_live_table(md, &srcu_idx); 2569 2570 while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) { 2571 spin_lock_irq(&md->deferred_lock); 2572 c = bio_list_pop(&md->deferred); 2573 spin_unlock_irq(&md->deferred_lock); 2574 2575 if (!c) 2576 break; 2577 2578 if (dm_request_based(md)) 2579 generic_make_request(c); 2580 else 2581 __split_and_process_bio(md, map, c); 2582 } 2583 2584 dm_put_live_table(md, srcu_idx); 2585 } 2586 2587 static void dm_queue_flush(struct mapped_device *md) 2588 { 2589 clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); 2590 smp_mb__after_clear_bit(); 2591 queue_work(md->wq, &md->work); 2592 } 2593 2594 /* 2595 * Swap in a new table, returning the old one for the caller to destroy. 2596 */ 2597 struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table) 2598 { 2599 struct dm_table *live_map = NULL, *map = ERR_PTR(-EINVAL); 2600 struct queue_limits limits; 2601 int r; 2602 2603 mutex_lock(&md->suspend_lock); 2604 2605 /* device must be suspended */ 2606 if (!dm_suspended_md(md)) 2607 goto out; 2608 2609 /* 2610 * If the new table has no data devices, retain the existing limits. 2611 * This helps multipath with queue_if_no_path if all paths disappear, 2612 * then new I/O is queued based on these limits, and then some paths 2613 * reappear. 2614 */ 2615 if (dm_table_has_no_data_devices(table)) { 2616 live_map = dm_get_live_table_fast(md); 2617 if (live_map) 2618 limits = md->queue->limits; 2619 dm_put_live_table_fast(md); 2620 } 2621 2622 if (!live_map) { 2623 r = dm_calculate_queue_limits(table, &limits); 2624 if (r) { 2625 map = ERR_PTR(r); 2626 goto out; 2627 } 2628 } 2629 2630 map = __bind(md, table, &limits); 2631 2632 out: 2633 mutex_unlock(&md->suspend_lock); 2634 return map; 2635 } 2636 2637 /* 2638 * Functions to lock and unlock any filesystem running on the 2639 * device. 2640 */ 2641 static int lock_fs(struct mapped_device *md) 2642 { 2643 int r; 2644 2645 WARN_ON(md->frozen_sb); 2646 2647 md->frozen_sb = freeze_bdev(md->bdev); 2648 if (IS_ERR(md->frozen_sb)) { 2649 r = PTR_ERR(md->frozen_sb); 2650 md->frozen_sb = NULL; 2651 return r; 2652 } 2653 2654 set_bit(DMF_FROZEN, &md->flags); 2655 2656 return 0; 2657 } 2658 2659 static void unlock_fs(struct mapped_device *md) 2660 { 2661 if (!test_bit(DMF_FROZEN, &md->flags)) 2662 return; 2663 2664 thaw_bdev(md->bdev, md->frozen_sb); 2665 md->frozen_sb = NULL; 2666 clear_bit(DMF_FROZEN, &md->flags); 2667 } 2668 2669 /* 2670 * We need to be able to change a mapping table under a mounted 2671 * filesystem. For example we might want to move some data in 2672 * the background. Before the table can be swapped with 2673 * dm_bind_table, dm_suspend must be called to flush any in 2674 * flight bios and ensure that any further io gets deferred. 2675 */ 2676 /* 2677 * Suspend mechanism in request-based dm. 2678 * 2679 * 1. Flush all I/Os by lock_fs() if needed. 2680 * 2. Stop dispatching any I/O by stopping the request_queue. 2681 * 3. Wait for all in-flight I/Os to be completed or requeued. 2682 * 2683 * To abort suspend, start the request_queue. 2684 */ 2685 int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 2686 { 2687 struct dm_table *map = NULL; 2688 int r = 0; 2689 int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0; 2690 int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0; 2691 2692 mutex_lock(&md->suspend_lock); 2693 2694 if (dm_suspended_md(md)) { 2695 r = -EINVAL; 2696 goto out_unlock; 2697 } 2698 2699 map = md->map; 2700 2701 /* 2702 * DMF_NOFLUSH_SUSPENDING must be set before presuspend. 2703 * This flag is cleared before dm_suspend returns. 2704 */ 2705 if (noflush) 2706 set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 2707 2708 /* This does not get reverted if there's an error later. */ 2709 dm_table_presuspend_targets(map); 2710 2711 /* 2712 * Flush I/O to the device. 2713 * Any I/O submitted after lock_fs() may not be flushed. 2714 * noflush takes precedence over do_lockfs. 2715 * (lock_fs() flushes I/Os and waits for them to complete.) 2716 */ 2717 if (!noflush && do_lockfs) { 2718 r = lock_fs(md); 2719 if (r) 2720 goto out_unlock; 2721 } 2722 2723 /* 2724 * Here we must make sure that no processes are submitting requests 2725 * to target drivers i.e. no one may be executing 2726 * __split_and_process_bio. This is called from dm_request and 2727 * dm_wq_work. 2728 * 2729 * To get all processes out of __split_and_process_bio in dm_request, 2730 * we take the write lock. To prevent any process from reentering 2731 * __split_and_process_bio from dm_request and quiesce the thread 2732 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call 2733 * flush_workqueue(md->wq). 2734 */ 2735 set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); 2736 synchronize_srcu(&md->io_barrier); 2737 2738 /* 2739 * Stop md->queue before flushing md->wq in case request-based 2740 * dm defers requests to md->wq from md->queue. 2741 */ 2742 if (dm_request_based(md)) 2743 stop_queue(md->queue); 2744 2745 flush_workqueue(md->wq); 2746 2747 /* 2748 * At this point no more requests are entering target request routines. 2749 * We call dm_wait_for_completion to wait for all existing requests 2750 * to finish. 2751 */ 2752 r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE); 2753 2754 if (noflush) 2755 clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 2756 synchronize_srcu(&md->io_barrier); 2757 2758 /* were we interrupted ? */ 2759 if (r < 0) { 2760 dm_queue_flush(md); 2761 2762 if (dm_request_based(md)) 2763 start_queue(md->queue); 2764 2765 unlock_fs(md); 2766 goto out_unlock; /* pushback list is already flushed, so skip flush */ 2767 } 2768 2769 /* 2770 * If dm_wait_for_completion returned 0, the device is completely 2771 * quiescent now. There is no request-processing activity. All new 2772 * requests are being added to md->deferred list. 2773 */ 2774 2775 set_bit(DMF_SUSPENDED, &md->flags); 2776 2777 dm_table_postsuspend_targets(map); 2778 2779 out_unlock: 2780 mutex_unlock(&md->suspend_lock); 2781 return r; 2782 } 2783 2784 int dm_resume(struct mapped_device *md) 2785 { 2786 int r = -EINVAL; 2787 struct dm_table *map = NULL; 2788 2789 mutex_lock(&md->suspend_lock); 2790 if (!dm_suspended_md(md)) 2791 goto out; 2792 2793 map = md->map; 2794 if (!map || !dm_table_get_size(map)) 2795 goto out; 2796 2797 r = dm_table_resume_targets(map); 2798 if (r) 2799 goto out; 2800 2801 dm_queue_flush(md); 2802 2803 /* 2804 * Flushing deferred I/Os must be done after targets are resumed 2805 * so that mapping of targets can work correctly. 2806 * Request-based dm is queueing the deferred I/Os in its request_queue. 2807 */ 2808 if (dm_request_based(md)) 2809 start_queue(md->queue); 2810 2811 unlock_fs(md); 2812 2813 clear_bit(DMF_SUSPENDED, &md->flags); 2814 2815 r = 0; 2816 out: 2817 mutex_unlock(&md->suspend_lock); 2818 2819 return r; 2820 } 2821 2822 /* 2823 * Internal suspend/resume works like userspace-driven suspend. It waits 2824 * until all bios finish and prevents issuing new bios to the target drivers. 2825 * It may be used only from the kernel. 2826 * 2827 * Internal suspend holds md->suspend_lock, which prevents interaction with 2828 * userspace-driven suspend. 2829 */ 2830 2831 void dm_internal_suspend(struct mapped_device *md) 2832 { 2833 mutex_lock(&md->suspend_lock); 2834 if (dm_suspended_md(md)) 2835 return; 2836 2837 set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags); 2838 synchronize_srcu(&md->io_barrier); 2839 flush_workqueue(md->wq); 2840 dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE); 2841 } 2842 2843 void dm_internal_resume(struct mapped_device *md) 2844 { 2845 if (dm_suspended_md(md)) 2846 goto done; 2847 2848 dm_queue_flush(md); 2849 2850 done: 2851 mutex_unlock(&md->suspend_lock); 2852 } 2853 2854 /*----------------------------------------------------------------- 2855 * Event notification. 2856 *---------------------------------------------------------------*/ 2857 int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, 2858 unsigned cookie) 2859 { 2860 char udev_cookie[DM_COOKIE_LENGTH]; 2861 char *envp[] = { udev_cookie, NULL }; 2862 2863 if (!cookie) 2864 return kobject_uevent(&disk_to_dev(md->disk)->kobj, action); 2865 else { 2866 snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u", 2867 DM_COOKIE_ENV_VAR_NAME, cookie); 2868 return kobject_uevent_env(&disk_to_dev(md->disk)->kobj, 2869 action, envp); 2870 } 2871 } 2872 2873 uint32_t dm_next_uevent_seq(struct mapped_device *md) 2874 { 2875 return atomic_add_return(1, &md->uevent_seq); 2876 } 2877 2878 uint32_t dm_get_event_nr(struct mapped_device *md) 2879 { 2880 return atomic_read(&md->event_nr); 2881 } 2882 2883 int dm_wait_event(struct mapped_device *md, int event_nr) 2884 { 2885 return wait_event_interruptible(md->eventq, 2886 (event_nr != atomic_read(&md->event_nr))); 2887 } 2888 2889 void dm_uevent_add(struct mapped_device *md, struct list_head *elist) 2890 { 2891 unsigned long flags; 2892 2893 spin_lock_irqsave(&md->uevent_lock, flags); 2894 list_add(elist, &md->uevent_list); 2895 spin_unlock_irqrestore(&md->uevent_lock, flags); 2896 } 2897 2898 /* 2899 * The gendisk is only valid as long as you have a reference 2900 * count on 'md'. 2901 */ 2902 struct gendisk *dm_disk(struct mapped_device *md) 2903 { 2904 return md->disk; 2905 } 2906 2907 struct kobject *dm_kobject(struct mapped_device *md) 2908 { 2909 return &md->kobj; 2910 } 2911 2912 struct mapped_device *dm_get_from_kobject(struct kobject *kobj) 2913 { 2914 struct mapped_device *md; 2915 2916 md = container_of(kobj, struct mapped_device, kobj); 2917 2918 if (test_bit(DMF_FREEING, &md->flags) || 2919 dm_deleting_md(md)) 2920 return NULL; 2921 2922 dm_get(md); 2923 return md; 2924 } 2925 2926 struct completion *dm_get_completion_from_kobject(struct kobject *kobj) 2927 { 2928 struct mapped_device *md = container_of(kobj, struct mapped_device, kobj); 2929 2930 return &md->kobj_completion; 2931 } 2932 2933 int dm_suspended_md(struct mapped_device *md) 2934 { 2935 return test_bit(DMF_SUSPENDED, &md->flags); 2936 } 2937 2938 int dm_test_deferred_remove_flag(struct mapped_device *md) 2939 { 2940 return test_bit(DMF_DEFERRED_REMOVE, &md->flags); 2941 } 2942 2943 int dm_suspended(struct dm_target *ti) 2944 { 2945 return dm_suspended_md(dm_table_get_md(ti->table)); 2946 } 2947 EXPORT_SYMBOL_GPL(dm_suspended); 2948 2949 int dm_noflush_suspending(struct dm_target *ti) 2950 { 2951 return __noflush_suspending(dm_table_get_md(ti->table)); 2952 } 2953 EXPORT_SYMBOL_GPL(dm_noflush_suspending); 2954 2955 struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size) 2956 { 2957 struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL); 2958 struct kmem_cache *cachep; 2959 unsigned int pool_size; 2960 unsigned int front_pad; 2961 2962 if (!pools) 2963 return NULL; 2964 2965 if (type == DM_TYPE_BIO_BASED) { 2966 cachep = _io_cache; 2967 pool_size = dm_get_reserved_bio_based_ios(); 2968 front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone); 2969 } else if (type == DM_TYPE_REQUEST_BASED) { 2970 cachep = _rq_tio_cache; 2971 pool_size = dm_get_reserved_rq_based_ios(); 2972 front_pad = offsetof(struct dm_rq_clone_bio_info, clone); 2973 /* per_bio_data_size is not used. See __bind_mempools(). */ 2974 WARN_ON(per_bio_data_size != 0); 2975 } else 2976 goto out; 2977 2978 pools->io_pool = mempool_create_slab_pool(pool_size, cachep); 2979 if (!pools->io_pool) 2980 goto out; 2981 2982 pools->bs = bioset_create(pool_size, front_pad); 2983 if (!pools->bs) 2984 goto out; 2985 2986 if (integrity && bioset_integrity_create(pools->bs, pool_size)) 2987 goto out; 2988 2989 return pools; 2990 2991 out: 2992 dm_free_md_mempools(pools); 2993 2994 return NULL; 2995 } 2996 2997 void dm_free_md_mempools(struct dm_md_mempools *pools) 2998 { 2999 if (!pools) 3000 return; 3001 3002 if (pools->io_pool) 3003 mempool_destroy(pools->io_pool); 3004 3005 if (pools->bs) 3006 bioset_free(pools->bs); 3007 3008 kfree(pools); 3009 } 3010 3011 static const struct block_device_operations dm_blk_dops = { 3012 .open = dm_blk_open, 3013 .release = dm_blk_close, 3014 .ioctl = dm_blk_ioctl, 3015 .getgeo = dm_blk_getgeo, 3016 .owner = THIS_MODULE 3017 }; 3018 3019 EXPORT_SYMBOL(dm_get_mapinfo); 3020 3021 /* 3022 * module hooks 3023 */ 3024 module_init(dm_init); 3025 module_exit(dm_exit); 3026 3027 module_param(major, uint, 0); 3028 MODULE_PARM_DESC(major, "The major number of the device mapper"); 3029 3030 module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR); 3031 MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools"); 3032 3033 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR); 3034 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools"); 3035 3036 MODULE_DESCRIPTION(DM_NAME " driver"); 3037 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); 3038 MODULE_LICENSE("GPL"); 3039