drivers/md/dm.c

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