1 /* 2 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. 3 * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved. 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include "dm.h" 9 #include "dm-bio-list.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/buffer_head.h> 18 #include <linux/mempool.h> 19 #include <linux/slab.h> 20 #include <linux/idr.h> 21 #include <linux/hdreg.h> 22 #include <linux/blktrace_api.h> 23 #include <linux/smp_lock.h> 24 25 #define DM_MSG_PREFIX "core" 26 27 static const char *_name = DM_NAME; 28 29 static unsigned int major = 0; 30 static unsigned int _major = 0; 31 32 static DEFINE_SPINLOCK(_minor_lock); 33 /* 34 * One of these is allocated per bio. 35 */ 36 struct dm_io { 37 struct mapped_device *md; 38 int error; 39 struct bio *bio; 40 atomic_t io_count; 41 unsigned long start_time; 42 }; 43 44 /* 45 * One of these is allocated per target within a bio. Hopefully 46 * this will be simplified out one day. 47 */ 48 struct target_io { 49 struct dm_io *io; 50 struct dm_target *ti; 51 union map_info info; 52 }; 53 54 union map_info *dm_get_mapinfo(struct bio *bio) 55 { 56 if (bio && bio->bi_private) 57 return &((struct target_io *)bio->bi_private)->info; 58 return NULL; 59 } 60 61 #define MINOR_ALLOCED ((void *)-1) 62 63 /* 64 * Bits for the md->flags field. 65 */ 66 #define DMF_BLOCK_IO 0 67 #define DMF_SUSPENDED 1 68 #define DMF_FROZEN 2 69 #define DMF_FREEING 3 70 #define DMF_DELETING 4 71 #define DMF_NOFLUSH_SUSPENDING 5 72 73 struct mapped_device { 74 struct rw_semaphore io_lock; 75 struct semaphore suspend_lock; 76 spinlock_t pushback_lock; 77 rwlock_t map_lock; 78 atomic_t holders; 79 atomic_t open_count; 80 81 unsigned long flags; 82 83 request_queue_t *queue; 84 struct gendisk *disk; 85 char name[16]; 86 87 void *interface_ptr; 88 89 /* 90 * A list of ios that arrived while we were suspended. 91 */ 92 atomic_t pending; 93 wait_queue_head_t wait; 94 struct bio_list deferred; 95 struct bio_list pushback; 96 97 /* 98 * The current mapping. 99 */ 100 struct dm_table *map; 101 102 /* 103 * io objects are allocated from here. 104 */ 105 mempool_t *io_pool; 106 mempool_t *tio_pool; 107 108 struct bio_set *bs; 109 110 /* 111 * Event handling. 112 */ 113 atomic_t event_nr; 114 wait_queue_head_t eventq; 115 116 /* 117 * freeze/thaw support require holding onto a super block 118 */ 119 struct super_block *frozen_sb; 120 struct block_device *suspended_bdev; 121 122 /* forced geometry settings */ 123 struct hd_geometry geometry; 124 }; 125 126 #define MIN_IOS 256 127 static struct kmem_cache *_io_cache; 128 static struct kmem_cache *_tio_cache; 129 130 static int __init local_init(void) 131 { 132 int r; 133 134 /* allocate a slab for the dm_ios */ 135 _io_cache = kmem_cache_create("dm_io", 136 sizeof(struct dm_io), 0, 0, NULL, NULL); 137 if (!_io_cache) 138 return -ENOMEM; 139 140 /* allocate a slab for the target ios */ 141 _tio_cache = kmem_cache_create("dm_tio", sizeof(struct target_io), 142 0, 0, NULL, NULL); 143 if (!_tio_cache) { 144 kmem_cache_destroy(_io_cache); 145 return -ENOMEM; 146 } 147 148 _major = major; 149 r = register_blkdev(_major, _name); 150 if (r < 0) { 151 kmem_cache_destroy(_tio_cache); 152 kmem_cache_destroy(_io_cache); 153 return r; 154 } 155 156 if (!_major) 157 _major = r; 158 159 return 0; 160 } 161 162 static void local_exit(void) 163 { 164 kmem_cache_destroy(_tio_cache); 165 kmem_cache_destroy(_io_cache); 166 167 if (unregister_blkdev(_major, _name) < 0) 168 DMERR("unregister_blkdev failed"); 169 170 _major = 0; 171 172 DMINFO("cleaned up"); 173 } 174 175 int (*_inits[])(void) __initdata = { 176 local_init, 177 dm_target_init, 178 dm_linear_init, 179 dm_stripe_init, 180 dm_interface_init, 181 }; 182 183 void (*_exits[])(void) = { 184 local_exit, 185 dm_target_exit, 186 dm_linear_exit, 187 dm_stripe_exit, 188 dm_interface_exit, 189 }; 190 191 static int __init dm_init(void) 192 { 193 const int count = ARRAY_SIZE(_inits); 194 195 int r, i; 196 197 for (i = 0; i < count; i++) { 198 r = _inits[i](); 199 if (r) 200 goto bad; 201 } 202 203 return 0; 204 205 bad: 206 while (i--) 207 _exits[i](); 208 209 return r; 210 } 211 212 static void __exit dm_exit(void) 213 { 214 int i = ARRAY_SIZE(_exits); 215 216 while (i--) 217 _exits[i](); 218 } 219 220 /* 221 * Block device functions 222 */ 223 static int dm_blk_open(struct inode *inode, struct file *file) 224 { 225 struct mapped_device *md; 226 227 spin_lock(&_minor_lock); 228 229 md = inode->i_bdev->bd_disk->private_data; 230 if (!md) 231 goto out; 232 233 if (test_bit(DMF_FREEING, &md->flags) || 234 test_bit(DMF_DELETING, &md->flags)) { 235 md = NULL; 236 goto out; 237 } 238 239 dm_get(md); 240 atomic_inc(&md->open_count); 241 242 out: 243 spin_unlock(&_minor_lock); 244 245 return md ? 0 : -ENXIO; 246 } 247 248 static int dm_blk_close(struct inode *inode, struct file *file) 249 { 250 struct mapped_device *md; 251 252 md = inode->i_bdev->bd_disk->private_data; 253 atomic_dec(&md->open_count); 254 dm_put(md); 255 return 0; 256 } 257 258 int dm_open_count(struct mapped_device *md) 259 { 260 return atomic_read(&md->open_count); 261 } 262 263 /* 264 * Guarantees nothing is using the device before it's deleted. 265 */ 266 int dm_lock_for_deletion(struct mapped_device *md) 267 { 268 int r = 0; 269 270 spin_lock(&_minor_lock); 271 272 if (dm_open_count(md)) 273 r = -EBUSY; 274 else 275 set_bit(DMF_DELETING, &md->flags); 276 277 spin_unlock(&_minor_lock); 278 279 return r; 280 } 281 282 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo) 283 { 284 struct mapped_device *md = bdev->bd_disk->private_data; 285 286 return dm_get_geometry(md, geo); 287 } 288 289 static int dm_blk_ioctl(struct inode *inode, struct file *file, 290 unsigned int cmd, unsigned long arg) 291 { 292 struct mapped_device *md; 293 struct dm_table *map; 294 struct dm_target *tgt; 295 int r = -ENOTTY; 296 297 /* We don't really need this lock, but we do need 'inode'. */ 298 unlock_kernel(); 299 300 md = inode->i_bdev->bd_disk->private_data; 301 302 map = dm_get_table(md); 303 304 if (!map || !dm_table_get_size(map)) 305 goto out; 306 307 /* We only support devices that have a single target */ 308 if (dm_table_get_num_targets(map) != 1) 309 goto out; 310 311 tgt = dm_table_get_target(map, 0); 312 313 if (dm_suspended(md)) { 314 r = -EAGAIN; 315 goto out; 316 } 317 318 if (tgt->type->ioctl) 319 r = tgt->type->ioctl(tgt, inode, file, cmd, arg); 320 321 out: 322 dm_table_put(map); 323 324 lock_kernel(); 325 return r; 326 } 327 328 static inline struct dm_io *alloc_io(struct mapped_device *md) 329 { 330 return mempool_alloc(md->io_pool, GFP_NOIO); 331 } 332 333 static inline void free_io(struct mapped_device *md, struct dm_io *io) 334 { 335 mempool_free(io, md->io_pool); 336 } 337 338 static inline struct target_io *alloc_tio(struct mapped_device *md) 339 { 340 return mempool_alloc(md->tio_pool, GFP_NOIO); 341 } 342 343 static inline void free_tio(struct mapped_device *md, struct target_io *tio) 344 { 345 mempool_free(tio, md->tio_pool); 346 } 347 348 static void start_io_acct(struct dm_io *io) 349 { 350 struct mapped_device *md = io->md; 351 352 io->start_time = jiffies; 353 354 preempt_disable(); 355 disk_round_stats(dm_disk(md)); 356 preempt_enable(); 357 dm_disk(md)->in_flight = atomic_inc_return(&md->pending); 358 } 359 360 static int end_io_acct(struct dm_io *io) 361 { 362 struct mapped_device *md = io->md; 363 struct bio *bio = io->bio; 364 unsigned long duration = jiffies - io->start_time; 365 int pending; 366 int rw = bio_data_dir(bio); 367 368 preempt_disable(); 369 disk_round_stats(dm_disk(md)); 370 preempt_enable(); 371 dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending); 372 373 disk_stat_add(dm_disk(md), ticks[rw], duration); 374 375 return !pending; 376 } 377 378 /* 379 * Add the bio to the list of deferred io. 380 */ 381 static int queue_io(struct mapped_device *md, struct bio *bio) 382 { 383 down_write(&md->io_lock); 384 385 if (!test_bit(DMF_BLOCK_IO, &md->flags)) { 386 up_write(&md->io_lock); 387 return 1; 388 } 389 390 bio_list_add(&md->deferred, bio); 391 392 up_write(&md->io_lock); 393 return 0; /* deferred successfully */ 394 } 395 396 /* 397 * Everyone (including functions in this file), should use this 398 * function to access the md->map field, and make sure they call 399 * dm_table_put() when finished. 400 */ 401 struct dm_table *dm_get_table(struct mapped_device *md) 402 { 403 struct dm_table *t; 404 405 read_lock(&md->map_lock); 406 t = md->map; 407 if (t) 408 dm_table_get(t); 409 read_unlock(&md->map_lock); 410 411 return t; 412 } 413 414 /* 415 * Get the geometry associated with a dm device 416 */ 417 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo) 418 { 419 *geo = md->geometry; 420 421 return 0; 422 } 423 424 /* 425 * Set the geometry of a device. 426 */ 427 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo) 428 { 429 sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors; 430 431 if (geo->start > sz) { 432 DMWARN("Start sector is beyond the geometry limits."); 433 return -EINVAL; 434 } 435 436 md->geometry = *geo; 437 438 return 0; 439 } 440 441 /*----------------------------------------------------------------- 442 * CRUD START: 443 * A more elegant soln is in the works that uses the queue 444 * merge fn, unfortunately there are a couple of changes to 445 * the block layer that I want to make for this. So in the 446 * interests of getting something for people to use I give 447 * you this clearly demarcated crap. 448 *---------------------------------------------------------------*/ 449 450 static int __noflush_suspending(struct mapped_device *md) 451 { 452 return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 453 } 454 455 /* 456 * Decrements the number of outstanding ios that a bio has been 457 * cloned into, completing the original io if necc. 458 */ 459 static void dec_pending(struct dm_io *io, int error) 460 { 461 unsigned long flags; 462 463 /* Push-back supersedes any I/O errors */ 464 if (error && !(io->error > 0 && __noflush_suspending(io->md))) 465 io->error = error; 466 467 if (atomic_dec_and_test(&io->io_count)) { 468 if (io->error == DM_ENDIO_REQUEUE) { 469 /* 470 * Target requested pushing back the I/O. 471 * This must be handled before the sleeper on 472 * suspend queue merges the pushback list. 473 */ 474 spin_lock_irqsave(&io->md->pushback_lock, flags); 475 if (__noflush_suspending(io->md)) 476 bio_list_add(&io->md->pushback, io->bio); 477 else 478 /* noflush suspend was interrupted. */ 479 io->error = -EIO; 480 spin_unlock_irqrestore(&io->md->pushback_lock, flags); 481 } 482 483 if (end_io_acct(io)) 484 /* nudge anyone waiting on suspend queue */ 485 wake_up(&io->md->wait); 486 487 if (io->error != DM_ENDIO_REQUEUE) { 488 blk_add_trace_bio(io->md->queue, io->bio, 489 BLK_TA_COMPLETE); 490 491 bio_endio(io->bio, io->bio->bi_size, io->error); 492 } 493 494 free_io(io->md, io); 495 } 496 } 497 498 static int clone_endio(struct bio *bio, unsigned int done, int error) 499 { 500 int r = 0; 501 struct target_io *tio = bio->bi_private; 502 struct mapped_device *md = tio->io->md; 503 dm_endio_fn endio = tio->ti->type->end_io; 504 505 if (bio->bi_size) 506 return 1; 507 508 if (!bio_flagged(bio, BIO_UPTODATE) && !error) 509 error = -EIO; 510 511 if (endio) { 512 r = endio(tio->ti, bio, error, &tio->info); 513 if (r < 0 || r == DM_ENDIO_REQUEUE) 514 /* 515 * error and requeue request are handled 516 * in dec_pending(). 517 */ 518 error = r; 519 else if (r == DM_ENDIO_INCOMPLETE) 520 /* The target will handle the io */ 521 return 1; 522 else if (r) { 523 DMWARN("unimplemented target endio return value: %d", r); 524 BUG(); 525 } 526 } 527 528 dec_pending(tio->io, error); 529 530 /* 531 * Store md for cleanup instead of tio which is about to get freed. 532 */ 533 bio->bi_private = md->bs; 534 535 bio_put(bio); 536 free_tio(md, tio); 537 return r; 538 } 539 540 static sector_t max_io_len(struct mapped_device *md, 541 sector_t sector, struct dm_target *ti) 542 { 543 sector_t offset = sector - ti->begin; 544 sector_t len = ti->len - offset; 545 546 /* 547 * Does the target need to split even further ? 548 */ 549 if (ti->split_io) { 550 sector_t boundary; 551 boundary = ((offset + ti->split_io) & ~(ti->split_io - 1)) 552 - offset; 553 if (len > boundary) 554 len = boundary; 555 } 556 557 return len; 558 } 559 560 static void __map_bio(struct dm_target *ti, struct bio *clone, 561 struct target_io *tio) 562 { 563 int r; 564 sector_t sector; 565 struct mapped_device *md; 566 567 /* 568 * Sanity checks. 569 */ 570 BUG_ON(!clone->bi_size); 571 572 clone->bi_end_io = clone_endio; 573 clone->bi_private = tio; 574 575 /* 576 * Map the clone. If r == 0 we don't need to do 577 * anything, the target has assumed ownership of 578 * this io. 579 */ 580 atomic_inc(&tio->io->io_count); 581 sector = clone->bi_sector; 582 r = ti->type->map(ti, clone, &tio->info); 583 if (r == DM_MAPIO_REMAPPED) { 584 /* the bio has been remapped so dispatch it */ 585 586 blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone, 587 tio->io->bio->bi_bdev->bd_dev, sector, 588 clone->bi_sector); 589 590 generic_make_request(clone); 591 } else if (r < 0 || r == DM_MAPIO_REQUEUE) { 592 /* error the io and bail out, or requeue it if needed */ 593 md = tio->io->md; 594 dec_pending(tio->io, r); 595 /* 596 * Store bio_set for cleanup. 597 */ 598 clone->bi_private = md->bs; 599 bio_put(clone); 600 free_tio(md, tio); 601 } else if (r) { 602 DMWARN("unimplemented target map return value: %d", r); 603 BUG(); 604 } 605 } 606 607 struct clone_info { 608 struct mapped_device *md; 609 struct dm_table *map; 610 struct bio *bio; 611 struct dm_io *io; 612 sector_t sector; 613 sector_t sector_count; 614 unsigned short idx; 615 }; 616 617 static void dm_bio_destructor(struct bio *bio) 618 { 619 struct bio_set *bs = bio->bi_private; 620 621 bio_free(bio, bs); 622 } 623 624 /* 625 * Creates a little bio that is just does part of a bvec. 626 */ 627 static struct bio *split_bvec(struct bio *bio, sector_t sector, 628 unsigned short idx, unsigned int offset, 629 unsigned int len, struct bio_set *bs) 630 { 631 struct bio *clone; 632 struct bio_vec *bv = bio->bi_io_vec + idx; 633 634 clone = bio_alloc_bioset(GFP_NOIO, 1, bs); 635 clone->bi_destructor = dm_bio_destructor; 636 *clone->bi_io_vec = *bv; 637 638 clone->bi_sector = sector; 639 clone->bi_bdev = bio->bi_bdev; 640 clone->bi_rw = bio->bi_rw; 641 clone->bi_vcnt = 1; 642 clone->bi_size = to_bytes(len); 643 clone->bi_io_vec->bv_offset = offset; 644 clone->bi_io_vec->bv_len = clone->bi_size; 645 646 return clone; 647 } 648 649 /* 650 * Creates a bio that consists of range of complete bvecs. 651 */ 652 static struct bio *clone_bio(struct bio *bio, sector_t sector, 653 unsigned short idx, unsigned short bv_count, 654 unsigned int len, struct bio_set *bs) 655 { 656 struct bio *clone; 657 658 clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs); 659 __bio_clone(clone, bio); 660 clone->bi_destructor = dm_bio_destructor; 661 clone->bi_sector = sector; 662 clone->bi_idx = idx; 663 clone->bi_vcnt = idx + bv_count; 664 clone->bi_size = to_bytes(len); 665 clone->bi_flags &= ~(1 << BIO_SEG_VALID); 666 667 return clone; 668 } 669 670 static void __clone_and_map(struct clone_info *ci) 671 { 672 struct bio *clone, *bio = ci->bio; 673 struct dm_target *ti = dm_table_find_target(ci->map, ci->sector); 674 sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti); 675 struct target_io *tio; 676 677 /* 678 * Allocate a target io object. 679 */ 680 tio = alloc_tio(ci->md); 681 tio->io = ci->io; 682 tio->ti = ti; 683 memset(&tio->info, 0, sizeof(tio->info)); 684 685 if (ci->sector_count <= max) { 686 /* 687 * Optimise for the simple case where we can do all of 688 * the remaining io with a single clone. 689 */ 690 clone = clone_bio(bio, ci->sector, ci->idx, 691 bio->bi_vcnt - ci->idx, ci->sector_count, 692 ci->md->bs); 693 __map_bio(ti, clone, tio); 694 ci->sector_count = 0; 695 696 } else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) { 697 /* 698 * There are some bvecs that don't span targets. 699 * Do as many of these as possible. 700 */ 701 int i; 702 sector_t remaining = max; 703 sector_t bv_len; 704 705 for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) { 706 bv_len = to_sector(bio->bi_io_vec[i].bv_len); 707 708 if (bv_len > remaining) 709 break; 710 711 remaining -= bv_len; 712 len += bv_len; 713 } 714 715 clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len, 716 ci->md->bs); 717 __map_bio(ti, clone, tio); 718 719 ci->sector += len; 720 ci->sector_count -= len; 721 ci->idx = i; 722 723 } else { 724 /* 725 * Handle a bvec that must be split between two or more targets. 726 */ 727 struct bio_vec *bv = bio->bi_io_vec + ci->idx; 728 sector_t remaining = to_sector(bv->bv_len); 729 unsigned int offset = 0; 730 731 do { 732 if (offset) { 733 ti = dm_table_find_target(ci->map, ci->sector); 734 max = max_io_len(ci->md, ci->sector, ti); 735 736 tio = alloc_tio(ci->md); 737 tio->io = ci->io; 738 tio->ti = ti; 739 memset(&tio->info, 0, sizeof(tio->info)); 740 } 741 742 len = min(remaining, max); 743 744 clone = split_bvec(bio, ci->sector, ci->idx, 745 bv->bv_offset + offset, len, 746 ci->md->bs); 747 748 __map_bio(ti, clone, tio); 749 750 ci->sector += len; 751 ci->sector_count -= len; 752 offset += to_bytes(len); 753 } while (remaining -= len); 754 755 ci->idx++; 756 } 757 } 758 759 /* 760 * Split the bio into several clones. 761 */ 762 static void __split_bio(struct mapped_device *md, struct bio *bio) 763 { 764 struct clone_info ci; 765 766 ci.map = dm_get_table(md); 767 if (!ci.map) { 768 bio_io_error(bio, bio->bi_size); 769 return; 770 } 771 772 ci.md = md; 773 ci.bio = bio; 774 ci.io = alloc_io(md); 775 ci.io->error = 0; 776 atomic_set(&ci.io->io_count, 1); 777 ci.io->bio = bio; 778 ci.io->md = md; 779 ci.sector = bio->bi_sector; 780 ci.sector_count = bio_sectors(bio); 781 ci.idx = bio->bi_idx; 782 783 start_io_acct(ci.io); 784 while (ci.sector_count) 785 __clone_and_map(&ci); 786 787 /* drop the extra reference count */ 788 dec_pending(ci.io, 0); 789 dm_table_put(ci.map); 790 } 791 /*----------------------------------------------------------------- 792 * CRUD END 793 *---------------------------------------------------------------*/ 794 795 /* 796 * The request function that just remaps the bio built up by 797 * dm_merge_bvec. 798 */ 799 static int dm_request(request_queue_t *q, struct bio *bio) 800 { 801 int r; 802 int rw = bio_data_dir(bio); 803 struct mapped_device *md = q->queuedata; 804 805 down_read(&md->io_lock); 806 807 disk_stat_inc(dm_disk(md), ios[rw]); 808 disk_stat_add(dm_disk(md), sectors[rw], bio_sectors(bio)); 809 810 /* 811 * If we're suspended we have to queue 812 * this io for later. 813 */ 814 while (test_bit(DMF_BLOCK_IO, &md->flags)) { 815 up_read(&md->io_lock); 816 817 if (bio_rw(bio) == READA) { 818 bio_io_error(bio, bio->bi_size); 819 return 0; 820 } 821 822 r = queue_io(md, bio); 823 if (r < 0) { 824 bio_io_error(bio, bio->bi_size); 825 return 0; 826 827 } else if (r == 0) 828 return 0; /* deferred successfully */ 829 830 /* 831 * We're in a while loop, because someone could suspend 832 * before we get to the following read lock. 833 */ 834 down_read(&md->io_lock); 835 } 836 837 __split_bio(md, bio); 838 up_read(&md->io_lock); 839 return 0; 840 } 841 842 static int dm_flush_all(request_queue_t *q, struct gendisk *disk, 843 sector_t *error_sector) 844 { 845 struct mapped_device *md = q->queuedata; 846 struct dm_table *map = dm_get_table(md); 847 int ret = -ENXIO; 848 849 if (map) { 850 ret = dm_table_flush_all(map); 851 dm_table_put(map); 852 } 853 854 return ret; 855 } 856 857 static void dm_unplug_all(request_queue_t *q) 858 { 859 struct mapped_device *md = q->queuedata; 860 struct dm_table *map = dm_get_table(md); 861 862 if (map) { 863 dm_table_unplug_all(map); 864 dm_table_put(map); 865 } 866 } 867 868 static int dm_any_congested(void *congested_data, int bdi_bits) 869 { 870 int r; 871 struct mapped_device *md = (struct mapped_device *) congested_data; 872 struct dm_table *map = dm_get_table(md); 873 874 if (!map || test_bit(DMF_BLOCK_IO, &md->flags)) 875 r = bdi_bits; 876 else 877 r = dm_table_any_congested(map, bdi_bits); 878 879 dm_table_put(map); 880 return r; 881 } 882 883 /*----------------------------------------------------------------- 884 * An IDR is used to keep track of allocated minor numbers. 885 *---------------------------------------------------------------*/ 886 static DEFINE_IDR(_minor_idr); 887 888 static void free_minor(int minor) 889 { 890 spin_lock(&_minor_lock); 891 idr_remove(&_minor_idr, minor); 892 spin_unlock(&_minor_lock); 893 } 894 895 /* 896 * See if the device with a specific minor # is free. 897 */ 898 static int specific_minor(struct mapped_device *md, int minor) 899 { 900 int r, m; 901 902 if (minor >= (1 << MINORBITS)) 903 return -EINVAL; 904 905 r = idr_pre_get(&_minor_idr, GFP_KERNEL); 906 if (!r) 907 return -ENOMEM; 908 909 spin_lock(&_minor_lock); 910 911 if (idr_find(&_minor_idr, minor)) { 912 r = -EBUSY; 913 goto out; 914 } 915 916 r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m); 917 if (r) 918 goto out; 919 920 if (m != minor) { 921 idr_remove(&_minor_idr, m); 922 r = -EBUSY; 923 goto out; 924 } 925 926 out: 927 spin_unlock(&_minor_lock); 928 return r; 929 } 930 931 static int next_free_minor(struct mapped_device *md, int *minor) 932 { 933 int r, m; 934 935 r = idr_pre_get(&_minor_idr, GFP_KERNEL); 936 if (!r) 937 return -ENOMEM; 938 939 spin_lock(&_minor_lock); 940 941 r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m); 942 if (r) { 943 goto out; 944 } 945 946 if (m >= (1 << MINORBITS)) { 947 idr_remove(&_minor_idr, m); 948 r = -ENOSPC; 949 goto out; 950 } 951 952 *minor = m; 953 954 out: 955 spin_unlock(&_minor_lock); 956 return r; 957 } 958 959 static struct block_device_operations dm_blk_dops; 960 961 /* 962 * Allocate and initialise a blank device with a given minor. 963 */ 964 static struct mapped_device *alloc_dev(int minor) 965 { 966 int r; 967 struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL); 968 void *old_md; 969 970 if (!md) { 971 DMWARN("unable to allocate device, out of memory."); 972 return NULL; 973 } 974 975 if (!try_module_get(THIS_MODULE)) 976 goto bad0; 977 978 /* get a minor number for the dev */ 979 if (minor == DM_ANY_MINOR) 980 r = next_free_minor(md, &minor); 981 else 982 r = specific_minor(md, minor); 983 if (r < 0) 984 goto bad1; 985 986 memset(md, 0, sizeof(*md)); 987 init_rwsem(&md->io_lock); 988 init_MUTEX(&md->suspend_lock); 989 spin_lock_init(&md->pushback_lock); 990 rwlock_init(&md->map_lock); 991 atomic_set(&md->holders, 1); 992 atomic_set(&md->open_count, 0); 993 atomic_set(&md->event_nr, 0); 994 995 md->queue = blk_alloc_queue(GFP_KERNEL); 996 if (!md->queue) 997 goto bad1_free_minor; 998 999 md->queue->queuedata = md; 1000 md->queue->backing_dev_info.congested_fn = dm_any_congested; 1001 md->queue->backing_dev_info.congested_data = md; 1002 blk_queue_make_request(md->queue, dm_request); 1003 blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); 1004 md->queue->unplug_fn = dm_unplug_all; 1005 md->queue->issue_flush_fn = dm_flush_all; 1006 1007 md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache); 1008 if (!md->io_pool) 1009 goto bad2; 1010 1011 md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache); 1012 if (!md->tio_pool) 1013 goto bad3; 1014 1015 md->bs = bioset_create(16, 16, 4); 1016 if (!md->bs) 1017 goto bad_no_bioset; 1018 1019 md->disk = alloc_disk(1); 1020 if (!md->disk) 1021 goto bad4; 1022 1023 atomic_set(&md->pending, 0); 1024 init_waitqueue_head(&md->wait); 1025 init_waitqueue_head(&md->eventq); 1026 1027 md->disk->major = _major; 1028 md->disk->first_minor = minor; 1029 md->disk->fops = &dm_blk_dops; 1030 md->disk->queue = md->queue; 1031 md->disk->private_data = md; 1032 sprintf(md->disk->disk_name, "dm-%d", minor); 1033 add_disk(md->disk); 1034 format_dev_t(md->name, MKDEV(_major, minor)); 1035 1036 /* Populate the mapping, nobody knows we exist yet */ 1037 spin_lock(&_minor_lock); 1038 old_md = idr_replace(&_minor_idr, md, minor); 1039 spin_unlock(&_minor_lock); 1040 1041 BUG_ON(old_md != MINOR_ALLOCED); 1042 1043 return md; 1044 1045 bad4: 1046 bioset_free(md->bs); 1047 bad_no_bioset: 1048 mempool_destroy(md->tio_pool); 1049 bad3: 1050 mempool_destroy(md->io_pool); 1051 bad2: 1052 blk_cleanup_queue(md->queue); 1053 bad1_free_minor: 1054 free_minor(minor); 1055 bad1: 1056 module_put(THIS_MODULE); 1057 bad0: 1058 kfree(md); 1059 return NULL; 1060 } 1061 1062 static void free_dev(struct mapped_device *md) 1063 { 1064 int minor = md->disk->first_minor; 1065 1066 if (md->suspended_bdev) { 1067 thaw_bdev(md->suspended_bdev, NULL); 1068 bdput(md->suspended_bdev); 1069 } 1070 mempool_destroy(md->tio_pool); 1071 mempool_destroy(md->io_pool); 1072 bioset_free(md->bs); 1073 del_gendisk(md->disk); 1074 free_minor(minor); 1075 1076 spin_lock(&_minor_lock); 1077 md->disk->private_data = NULL; 1078 spin_unlock(&_minor_lock); 1079 1080 put_disk(md->disk); 1081 blk_cleanup_queue(md->queue); 1082 module_put(THIS_MODULE); 1083 kfree(md); 1084 } 1085 1086 /* 1087 * Bind a table to the device. 1088 */ 1089 static void event_callback(void *context) 1090 { 1091 struct mapped_device *md = (struct mapped_device *) context; 1092 1093 atomic_inc(&md->event_nr); 1094 wake_up(&md->eventq); 1095 } 1096 1097 static void __set_size(struct mapped_device *md, sector_t size) 1098 { 1099 set_capacity(md->disk, size); 1100 1101 mutex_lock(&md->suspended_bdev->bd_inode->i_mutex); 1102 i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); 1103 mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex); 1104 } 1105 1106 static int __bind(struct mapped_device *md, struct dm_table *t) 1107 { 1108 request_queue_t *q = md->queue; 1109 sector_t size; 1110 1111 size = dm_table_get_size(t); 1112 1113 /* 1114 * Wipe any geometry if the size of the table changed. 1115 */ 1116 if (size != get_capacity(md->disk)) 1117 memset(&md->geometry, 0, sizeof(md->geometry)); 1118 1119 if (md->suspended_bdev) 1120 __set_size(md, size); 1121 if (size == 0) 1122 return 0; 1123 1124 dm_table_get(t); 1125 dm_table_event_callback(t, event_callback, md); 1126 1127 write_lock(&md->map_lock); 1128 md->map = t; 1129 dm_table_set_restrictions(t, q); 1130 write_unlock(&md->map_lock); 1131 1132 return 0; 1133 } 1134 1135 static void __unbind(struct mapped_device *md) 1136 { 1137 struct dm_table *map = md->map; 1138 1139 if (!map) 1140 return; 1141 1142 dm_table_event_callback(map, NULL, NULL); 1143 write_lock(&md->map_lock); 1144 md->map = NULL; 1145 write_unlock(&md->map_lock); 1146 dm_table_put(map); 1147 } 1148 1149 /* 1150 * Constructor for a new device. 1151 */ 1152 int dm_create(int minor, struct mapped_device **result) 1153 { 1154 struct mapped_device *md; 1155 1156 md = alloc_dev(minor); 1157 if (!md) 1158 return -ENXIO; 1159 1160 *result = md; 1161 return 0; 1162 } 1163 1164 static struct mapped_device *dm_find_md(dev_t dev) 1165 { 1166 struct mapped_device *md; 1167 unsigned minor = MINOR(dev); 1168 1169 if (MAJOR(dev) != _major || minor >= (1 << MINORBITS)) 1170 return NULL; 1171 1172 spin_lock(&_minor_lock); 1173 1174 md = idr_find(&_minor_idr, minor); 1175 if (md && (md == MINOR_ALLOCED || 1176 (dm_disk(md)->first_minor != minor) || 1177 test_bit(DMF_FREEING, &md->flags))) { 1178 md = NULL; 1179 goto out; 1180 } 1181 1182 out: 1183 spin_unlock(&_minor_lock); 1184 1185 return md; 1186 } 1187 1188 struct mapped_device *dm_get_md(dev_t dev) 1189 { 1190 struct mapped_device *md = dm_find_md(dev); 1191 1192 if (md) 1193 dm_get(md); 1194 1195 return md; 1196 } 1197 1198 void *dm_get_mdptr(struct mapped_device *md) 1199 { 1200 return md->interface_ptr; 1201 } 1202 1203 void dm_set_mdptr(struct mapped_device *md, void *ptr) 1204 { 1205 md->interface_ptr = ptr; 1206 } 1207 1208 void dm_get(struct mapped_device *md) 1209 { 1210 atomic_inc(&md->holders); 1211 } 1212 1213 const char *dm_device_name(struct mapped_device *md) 1214 { 1215 return md->name; 1216 } 1217 EXPORT_SYMBOL_GPL(dm_device_name); 1218 1219 void dm_put(struct mapped_device *md) 1220 { 1221 struct dm_table *map; 1222 1223 BUG_ON(test_bit(DMF_FREEING, &md->flags)); 1224 1225 if (atomic_dec_and_lock(&md->holders, &_minor_lock)) { 1226 map = dm_get_table(md); 1227 idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor); 1228 set_bit(DMF_FREEING, &md->flags); 1229 spin_unlock(&_minor_lock); 1230 if (!dm_suspended(md)) { 1231 dm_table_presuspend_targets(map); 1232 dm_table_postsuspend_targets(map); 1233 } 1234 __unbind(md); 1235 dm_table_put(map); 1236 free_dev(md); 1237 } 1238 } 1239 1240 /* 1241 * Process the deferred bios 1242 */ 1243 static void __flush_deferred_io(struct mapped_device *md, struct bio *c) 1244 { 1245 struct bio *n; 1246 1247 while (c) { 1248 n = c->bi_next; 1249 c->bi_next = NULL; 1250 __split_bio(md, c); 1251 c = n; 1252 } 1253 } 1254 1255 /* 1256 * Swap in a new table (destroying old one). 1257 */ 1258 int dm_swap_table(struct mapped_device *md, struct dm_table *table) 1259 { 1260 int r = -EINVAL; 1261 1262 down(&md->suspend_lock); 1263 1264 /* device must be suspended */ 1265 if (!dm_suspended(md)) 1266 goto out; 1267 1268 /* without bdev, the device size cannot be changed */ 1269 if (!md->suspended_bdev) 1270 if (get_capacity(md->disk) != dm_table_get_size(table)) 1271 goto out; 1272 1273 __unbind(md); 1274 r = __bind(md, table); 1275 1276 out: 1277 up(&md->suspend_lock); 1278 return r; 1279 } 1280 1281 /* 1282 * Functions to lock and unlock any filesystem running on the 1283 * device. 1284 */ 1285 static int lock_fs(struct mapped_device *md) 1286 { 1287 int r; 1288 1289 WARN_ON(md->frozen_sb); 1290 1291 md->frozen_sb = freeze_bdev(md->suspended_bdev); 1292 if (IS_ERR(md->frozen_sb)) { 1293 r = PTR_ERR(md->frozen_sb); 1294 md->frozen_sb = NULL; 1295 return r; 1296 } 1297 1298 set_bit(DMF_FROZEN, &md->flags); 1299 1300 /* don't bdput right now, we don't want the bdev 1301 * to go away while it is locked. 1302 */ 1303 return 0; 1304 } 1305 1306 static void unlock_fs(struct mapped_device *md) 1307 { 1308 if (!test_bit(DMF_FROZEN, &md->flags)) 1309 return; 1310 1311 thaw_bdev(md->suspended_bdev, md->frozen_sb); 1312 md->frozen_sb = NULL; 1313 clear_bit(DMF_FROZEN, &md->flags); 1314 } 1315 1316 /* 1317 * We need to be able to change a mapping table under a mounted 1318 * filesystem. For example we might want to move some data in 1319 * the background. Before the table can be swapped with 1320 * dm_bind_table, dm_suspend must be called to flush any in 1321 * flight bios and ensure that any further io gets deferred. 1322 */ 1323 int dm_suspend(struct mapped_device *md, unsigned suspend_flags) 1324 { 1325 struct dm_table *map = NULL; 1326 unsigned long flags; 1327 DECLARE_WAITQUEUE(wait, current); 1328 struct bio *def; 1329 int r = -EINVAL; 1330 int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0; 1331 int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0; 1332 1333 down(&md->suspend_lock); 1334 1335 if (dm_suspended(md)) 1336 goto out_unlock; 1337 1338 map = dm_get_table(md); 1339 1340 /* 1341 * DMF_NOFLUSH_SUSPENDING must be set before presuspend. 1342 * This flag is cleared before dm_suspend returns. 1343 */ 1344 if (noflush) 1345 set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 1346 1347 /* This does not get reverted if there's an error later. */ 1348 dm_table_presuspend_targets(map); 1349 1350 /* bdget() can stall if the pending I/Os are not flushed */ 1351 if (!noflush) { 1352 md->suspended_bdev = bdget_disk(md->disk, 0); 1353 if (!md->suspended_bdev) { 1354 DMWARN("bdget failed in dm_suspend"); 1355 r = -ENOMEM; 1356 goto flush_and_out; 1357 } 1358 } 1359 1360 /* 1361 * Flush I/O to the device. 1362 * noflush supersedes do_lockfs, because lock_fs() needs to flush I/Os. 1363 */ 1364 if (do_lockfs && !noflush) { 1365 r = lock_fs(md); 1366 if (r) 1367 goto out; 1368 } 1369 1370 /* 1371 * First we set the BLOCK_IO flag so no more ios will be mapped. 1372 */ 1373 down_write(&md->io_lock); 1374 set_bit(DMF_BLOCK_IO, &md->flags); 1375 1376 add_wait_queue(&md->wait, &wait); 1377 up_write(&md->io_lock); 1378 1379 /* unplug */ 1380 if (map) 1381 dm_table_unplug_all(map); 1382 1383 /* 1384 * Then we wait for the already mapped ios to 1385 * complete. 1386 */ 1387 while (1) { 1388 set_current_state(TASK_INTERRUPTIBLE); 1389 1390 if (!atomic_read(&md->pending) || signal_pending(current)) 1391 break; 1392 1393 io_schedule(); 1394 } 1395 set_current_state(TASK_RUNNING); 1396 1397 down_write(&md->io_lock); 1398 remove_wait_queue(&md->wait, &wait); 1399 1400 if (noflush) { 1401 spin_lock_irqsave(&md->pushback_lock, flags); 1402 clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 1403 bio_list_merge_head(&md->deferred, &md->pushback); 1404 bio_list_init(&md->pushback); 1405 spin_unlock_irqrestore(&md->pushback_lock, flags); 1406 } 1407 1408 /* were we interrupted ? */ 1409 r = -EINTR; 1410 if (atomic_read(&md->pending)) { 1411 clear_bit(DMF_BLOCK_IO, &md->flags); 1412 def = bio_list_get(&md->deferred); 1413 __flush_deferred_io(md, def); 1414 up_write(&md->io_lock); 1415 unlock_fs(md); 1416 goto out; /* pushback list is already flushed, so skip flush */ 1417 } 1418 up_write(&md->io_lock); 1419 1420 dm_table_postsuspend_targets(map); 1421 1422 set_bit(DMF_SUSPENDED, &md->flags); 1423 1424 r = 0; 1425 1426 flush_and_out: 1427 if (r && noflush) { 1428 /* 1429 * Because there may be already I/Os in the pushback list, 1430 * flush them before return. 1431 */ 1432 down_write(&md->io_lock); 1433 1434 spin_lock_irqsave(&md->pushback_lock, flags); 1435 clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); 1436 bio_list_merge_head(&md->deferred, &md->pushback); 1437 bio_list_init(&md->pushback); 1438 spin_unlock_irqrestore(&md->pushback_lock, flags); 1439 1440 def = bio_list_get(&md->deferred); 1441 __flush_deferred_io(md, def); 1442 up_write(&md->io_lock); 1443 } 1444 1445 out: 1446 if (r && md->suspended_bdev) { 1447 bdput(md->suspended_bdev); 1448 md->suspended_bdev = NULL; 1449 } 1450 1451 dm_table_put(map); 1452 1453 out_unlock: 1454 up(&md->suspend_lock); 1455 return r; 1456 } 1457 1458 int dm_resume(struct mapped_device *md) 1459 { 1460 int r = -EINVAL; 1461 struct bio *def; 1462 struct dm_table *map = NULL; 1463 1464 down(&md->suspend_lock); 1465 if (!dm_suspended(md)) 1466 goto out; 1467 1468 map = dm_get_table(md); 1469 if (!map || !dm_table_get_size(map)) 1470 goto out; 1471 1472 r = dm_table_resume_targets(map); 1473 if (r) 1474 goto out; 1475 1476 down_write(&md->io_lock); 1477 clear_bit(DMF_BLOCK_IO, &md->flags); 1478 1479 def = bio_list_get(&md->deferred); 1480 __flush_deferred_io(md, def); 1481 up_write(&md->io_lock); 1482 1483 unlock_fs(md); 1484 1485 if (md->suspended_bdev) { 1486 bdput(md->suspended_bdev); 1487 md->suspended_bdev = NULL; 1488 } 1489 1490 clear_bit(DMF_SUSPENDED, &md->flags); 1491 1492 dm_table_unplug_all(map); 1493 1494 kobject_uevent(&md->disk->kobj, KOBJ_CHANGE); 1495 1496 r = 0; 1497 1498 out: 1499 dm_table_put(map); 1500 up(&md->suspend_lock); 1501 1502 return r; 1503 } 1504 1505 /*----------------------------------------------------------------- 1506 * Event notification. 1507 *---------------------------------------------------------------*/ 1508 uint32_t dm_get_event_nr(struct mapped_device *md) 1509 { 1510 return atomic_read(&md->event_nr); 1511 } 1512 1513 int dm_wait_event(struct mapped_device *md, int event_nr) 1514 { 1515 return wait_event_interruptible(md->eventq, 1516 (event_nr != atomic_read(&md->event_nr))); 1517 } 1518 1519 /* 1520 * The gendisk is only valid as long as you have a reference 1521 * count on 'md'. 1522 */ 1523 struct gendisk *dm_disk(struct mapped_device *md) 1524 { 1525 return md->disk; 1526 } 1527 1528 int dm_suspended(struct mapped_device *md) 1529 { 1530 return test_bit(DMF_SUSPENDED, &md->flags); 1531 } 1532 1533 int dm_noflush_suspending(struct dm_target *ti) 1534 { 1535 struct mapped_device *md = dm_table_get_md(ti->table); 1536 int r = __noflush_suspending(md); 1537 1538 dm_put(md); 1539 1540 return r; 1541 } 1542 EXPORT_SYMBOL_GPL(dm_noflush_suspending); 1543 1544 static struct block_device_operations dm_blk_dops = { 1545 .open = dm_blk_open, 1546 .release = dm_blk_close, 1547 .ioctl = dm_blk_ioctl, 1548 .getgeo = dm_blk_getgeo, 1549 .owner = THIS_MODULE 1550 }; 1551 1552 EXPORT_SYMBOL(dm_get_mapinfo); 1553 1554 /* 1555 * module hooks 1556 */ 1557 module_init(dm_init); 1558 module_exit(dm_exit); 1559 1560 module_param(major, uint, 0); 1561 MODULE_PARM_DESC(major, "The major number of the device mapper"); 1562 MODULE_DESCRIPTION(DM_NAME " driver"); 1563 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); 1564 MODULE_LICENSE("GPL"); 1565