drivers/md/dm-thin.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2011-2012 Red Hat UK.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm-thin-metadata.h"
   9 #include "dm-bio-prison-v1.h"
  10 #include "dm.h"
  11
  12 #include <linux/device-mapper.h>
  13 #include <linux/dm-io.h>
  14 #include <linux/dm-kcopyd.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/log2.h>
  17 #include <linux/list.h>
  18 #include <linux/rculist.h>
  19 #include <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/sort.h>
  24 #include <linux/rbtree.h>
  25
  26 #define DM_MSG_PREFIX   "thin"
  27
  28 /*
  29  * Tunable constants
  30  */
  31 #define ENDIO_HOOK_POOL_SIZE 1024
  32 #define MAPPING_POOL_SIZE 1024
  33 #define COMMIT_PERIOD HZ
  34 #define NO_SPACE_TIMEOUT_SECS 60
  35
  36 static unsigned int no_space_timeout_secs = NO_SPACE_TIMEOUT_SECS;
  37
  38 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle,
  39                 "A percentage of time allocated for copy on write");
  40
  41 /*
  42  * The block size of the device holding pool data must be
  43  * between 64KB and 1GB.
  44  */
  45 #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (64 * 1024 >> SECTOR_SHIFT)
  46 #define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
  47
  48 /*
  49  * Device id is restricted to 24 bits.
  50  */
  51 #define MAX_DEV_ID ((1 << 24) - 1)
  52
  53 /*
  54  * How do we handle breaking sharing of data blocks?
  55  * =================================================
  56  *
  57  * We use a standard copy-on-write btree to store the mappings for the
  58  * devices (note I'm talking about copy-on-write of the metadata here, not
  59  * the data).  When you take an internal snapshot you clone the root node
  60  * of the origin btree.  After this there is no concept of an origin or a
  61  * snapshot.  They are just two device trees that happen to point to the
  62  * same data blocks.
  63  *
  64  * When we get a write in we decide if it's to a shared data block using
  65  * some timestamp magic.  If it is, we have to break sharing.
  66  *
  67  * Let's say we write to a shared block in what was the origin.  The
  68  * steps are:
  69  *
  70  * i) plug io further to this physical block. (see bio_prison code).
  71  *
  72  * ii) quiesce any read io to that shared data block.  Obviously
  73  * including all devices that share this block.  (see dm_deferred_set code)
  74  *
  75  * iii) copy the data block to a newly allocate block.  This step can be
  76  * missed out if the io covers the block. (schedule_copy).
  77  *
  78  * iv) insert the new mapping into the origin's btree
  79  * (process_prepared_mapping).  This act of inserting breaks some
  80  * sharing of btree nodes between the two devices.  Breaking sharing only
  81  * effects the btree of that specific device.  Btrees for the other
  82  * devices that share the block never change.  The btree for the origin
  83  * device as it was after the last commit is untouched, ie. we're using
  84  * persistent data structures in the functional programming sense.
  85  *
  86  * v) unplug io to this physical block, including the io that triggered
  87  * the breaking of sharing.
  88  *
  89  * Steps (ii) and (iii) occur in parallel.
  90  *
  91  * The metadata _doesn't_ need to be committed before the io continues.  We
  92  * get away with this because the io is always written to a _new_ block.
  93  * If there's a crash, then:
  94  *
  95  * - The origin mapping will point to the old origin block (the shared
  96  * one).  This will contain the data as it was before the io that triggered
  97  * the breaking of sharing came in.
  98  *
  99  * - The snap mapping still points to the old block.  As it would after
 100  * the commit.
 101  *
 102  * The downside of this scheme is the timestamp magic isn't perfect, and
 103  * will continue to think that data block in the snapshot device is shared
 104  * even after the write to the origin has broken sharing.  I suspect data
 105  * blocks will typically be shared by many different devices, so we're
 106  * breaking sharing n + 1 times, rather than n, where n is the number of
 107  * devices that reference this data block.  At the moment I think the
 108  * benefits far, far outweigh the disadvantages.
 109  */
 110
 111 /*----------------------------------------------------------------*/
 112
 113 /*
 114  * Key building.
 115  */
 116 enum lock_space {
 117         VIRTUAL,
 118         PHYSICAL
 119 };
 120
 121 static bool build_key(struct dm_thin_device *td, enum lock_space ls,
 122                       dm_block_t b, dm_block_t e, struct dm_cell_key *key)
 123 {
 124         key->virtual = (ls == VIRTUAL);
 125         key->dev = dm_thin_dev_id(td);
 126         key->block_begin = b;
 127         key->block_end = e;
 128
 129         return dm_cell_key_has_valid_range(key);
 130 }
 131
 132 static void build_data_key(struct dm_thin_device *td, dm_block_t b,
 133                            struct dm_cell_key *key)
 134 {
 135         (void) build_key(td, PHYSICAL, b, b + 1llu, key);
 136 }
 137
 138 static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
 139                               struct dm_cell_key *key)
 140 {
 141         (void) build_key(td, VIRTUAL, b, b + 1llu, key);
 142 }
 143
 144 /*----------------------------------------------------------------*/
 145
 146 #define THROTTLE_THRESHOLD (1 * HZ)
 147
 148 struct throttle {
 149         struct rw_semaphore lock;
 150         unsigned long threshold;
 151         bool throttle_applied;
 152 };
 153
 154 static void throttle_init(struct throttle *t)
 155 {
 156         init_rwsem(&t->lock);
 157         t->throttle_applied = false;
 158 }
 159
 160 static void throttle_work_start(struct throttle *t)
 161 {
 162         t->threshold = jiffies + THROTTLE_THRESHOLD;
 163 }
 164
 165 static void throttle_work_update(struct throttle *t)
 166 {
 167         if (!t->throttle_applied && time_is_before_jiffies(t->threshold)) {
 168                 down_write(&t->lock);
 169                 t->throttle_applied = true;
 170         }
 171 }
 172
 173 static void throttle_work_complete(struct throttle *t)
 174 {
 175         if (t->throttle_applied) {
 176                 t->throttle_applied = false;
 177                 up_write(&t->lock);
 178         }
 179 }
 180
 181 static void throttle_lock(struct throttle *t)
 182 {
 183         down_read(&t->lock);
 184 }
 185
 186 static void throttle_unlock(struct throttle *t)
 187 {
 188         up_read(&t->lock);
 189 }
 190
 191 /*----------------------------------------------------------------*/
 192
 193 /*
 194  * A pool device ties together a metadata device and a data device.  It
 195  * also provides the interface for creating and destroying internal
 196  * devices.
 197  */
 198 struct dm_thin_new_mapping;
 199
 200 /*
 201  * The pool runs in various modes.  Ordered in degraded order for comparisons.
 202  */
 203 enum pool_mode {
 204         PM_WRITE,               /* metadata may be changed */
 205         PM_OUT_OF_DATA_SPACE,   /* metadata may be changed, though data may not be allocated */
 206
 207         /*
 208          * Like READ_ONLY, except may switch back to WRITE on metadata resize. Reported as READ_ONLY.
 209          */
 210         PM_OUT_OF_METADATA_SPACE,
 211         PM_READ_ONLY,           /* metadata may not be changed */
 212
 213         PM_FAIL,                /* all I/O fails */
 214 };
 215
 216 struct pool_features {
 217         enum pool_mode mode;
 218
 219         bool zero_new_blocks:1;
 220         bool discard_enabled:1;
 221         bool discard_passdown:1;
 222         bool error_if_no_space:1;
 223 };
 224
 225 struct thin_c;
 226 typedef void (*process_bio_fn)(struct thin_c *tc, struct bio *bio);
 227 typedef void (*process_cell_fn)(struct thin_c *tc, struct dm_bio_prison_cell *cell);
 228 typedef void (*process_mapping_fn)(struct dm_thin_new_mapping *m);
 229
 230 #define CELL_SORT_ARRAY_SIZE 8192
 231
 232 struct pool {
 233         struct list_head list;
 234         struct dm_target *ti;   /* Only set if a pool target is bound */
 235
 236         struct mapped_device *pool_md;
 237         struct block_device *data_dev;
 238         struct block_device *md_dev;
 239         struct dm_pool_metadata *pmd;
 240
 241         dm_block_t low_water_blocks;
 242         uint32_t sectors_per_block;
 243         int sectors_per_block_shift;
 244
 245         struct pool_features pf;
 246         bool low_water_triggered:1;     /* A dm event has been sent */
 247         bool suspended:1;
 248         bool out_of_data_space:1;
 249
 250         struct dm_bio_prison *prison;
 251         struct dm_kcopyd_client *copier;
 252
 253         struct work_struct worker;
 254         struct workqueue_struct *wq;
 255         struct throttle throttle;
 256         struct delayed_work waker;
 257         struct delayed_work no_space_timeout;
 258
 259         unsigned long last_commit_jiffies;
 260         unsigned int ref_count;
 261
 262         spinlock_t lock;
 263         struct bio_list deferred_flush_bios;
 264         struct bio_list deferred_flush_completions;
 265         struct list_head prepared_mappings;
 266         struct list_head prepared_discards;
 267         struct list_head prepared_discards_pt2;
 268         struct list_head active_thins;
 269
 270         struct dm_deferred_set *shared_read_ds;
 271         struct dm_deferred_set *all_io_ds;
 272
 273         struct dm_thin_new_mapping *next_mapping;
 274
 275         process_bio_fn process_bio;
 276         process_bio_fn process_discard;
 277
 278         process_cell_fn process_cell;
 279         process_cell_fn process_discard_cell;
 280
 281         process_mapping_fn process_prepared_mapping;
 282         process_mapping_fn process_prepared_discard;
 283         process_mapping_fn process_prepared_discard_pt2;
 284
 285         struct dm_bio_prison_cell **cell_sort_array;
 286
 287         mempool_t mapping_pool;
 288 };
 289
 290 static void metadata_operation_failed(struct pool *pool, const char *op, int r);
 291
 292 static enum pool_mode get_pool_mode(struct pool *pool)
 293 {
 294         return pool->pf.mode;
 295 }
 296
 297 static void notify_of_pool_mode_change(struct pool *pool)
 298 {
 299         static const char *descs[] = {
 300                 "write",
 301                 "out-of-data-space",
 302                 "read-only",
 303                 "read-only",
 304                 "fail"
 305         };
 306         const char *extra_desc = NULL;
 307         enum pool_mode mode = get_pool_mode(pool);
 308
 309         if (mode == PM_OUT_OF_DATA_SPACE) {
 310                 if (!pool->pf.error_if_no_space)
 311                         extra_desc = " (queue IO)";
 312                 else
 313                         extra_desc = " (error IO)";
 314         }
 315
 316         dm_table_event(pool->ti->table);
 317         DMINFO("%s: switching pool to %s%s mode",
 318                dm_device_name(pool->pool_md),
 319                descs[(int)mode], extra_desc ? : "");
 320 }
 321
 322 /*
 323  * Target context for a pool.
 324  */
 325 struct pool_c {
 326         struct dm_target *ti;
 327         struct pool *pool;
 328         struct dm_dev *data_dev;
 329         struct dm_dev *metadata_dev;
 330
 331         dm_block_t low_water_blocks;
 332         struct pool_features requested_pf; /* Features requested during table load */
 333         struct pool_features adjusted_pf;  /* Features used after adjusting for constituent devices */
 334 };
 335
 336 /*
 337  * Target context for a thin.
 338  */
 339 struct thin_c {
 340         struct list_head list;
 341         struct dm_dev *pool_dev;
 342         struct dm_dev *origin_dev;
 343         sector_t origin_size;
 344         dm_thin_id dev_id;
 345
 346         struct pool *pool;
 347         struct dm_thin_device *td;
 348         struct mapped_device *thin_md;
 349
 350         bool requeue_mode:1;
 351         spinlock_t lock;
 352         struct list_head deferred_cells;
 353         struct bio_list deferred_bio_list;
 354         struct bio_list retry_on_resume_list;
 355         struct rb_root sort_bio_list; /* sorted list of deferred bios */
 356
 357         /*
 358          * Ensures the thin is not destroyed until the worker has finished
 359          * iterating the active_thins list.
 360          */
 361         refcount_t refcount;
 362         struct completion can_destroy;
 363 };
 364
 365 /*----------------------------------------------------------------*/
 366
 367 static bool block_size_is_power_of_two(struct pool *pool)
 368 {
 369         return pool->sectors_per_block_shift >= 0;
 370 }
 371
 372 static sector_t block_to_sectors(struct pool *pool, dm_block_t b)
 373 {
 374         return block_size_is_power_of_two(pool) ?
 375                 (b << pool->sectors_per_block_shift) :
 376                 (b * pool->sectors_per_block);
 377 }
 378
 379 /*----------------------------------------------------------------*/
 380
 381 struct discard_op {
 382         struct thin_c *tc;
 383         struct blk_plug plug;
 384         struct bio *parent_bio;
 385         struct bio *bio;
 386 };
 387
 388 static void begin_discard(struct discard_op *op, struct thin_c *tc, struct bio *parent)
 389 {
 390         BUG_ON(!parent);
 391
 392         op->tc = tc;
 393         blk_start_plug(&op->plug);
 394         op->parent_bio = parent;
 395         op->bio = NULL;
 396 }
 397
 398 static int issue_discard(struct discard_op *op, dm_block_t data_b, dm_block_t data_e)
 399 {
 400         struct thin_c *tc = op->tc;
 401         sector_t s = block_to_sectors(tc->pool, data_b);
 402         sector_t len = block_to_sectors(tc->pool, data_e - data_b);
 403
 404         return __blkdev_issue_discard(tc->pool_dev->bdev, s, len, GFP_NOIO, &op->bio);
 405 }
 406
 407 static void end_discard(struct discard_op *op, int r)
 408 {
 409         if (op->bio) {
 410                 /*
 411                  * Even if one of the calls to issue_discard failed, we
 412                  * need to wait for the chain to complete.
 413                  */
 414                 bio_chain(op->bio, op->parent_bio);
 415                 op->bio->bi_opf = REQ_OP_DISCARD;
 416                 submit_bio(op->bio);
 417         }
 418
 419         blk_finish_plug(&op->plug);
 420
 421         /*
 422          * Even if r is set, there could be sub discards in flight that we
 423          * need to wait for.
 424          */
 425         if (r && !op->parent_bio->bi_status)
 426                 op->parent_bio->bi_status = errno_to_blk_status(r);
 427         bio_endio(op->parent_bio);
 428 }
 429
 430 /*----------------------------------------------------------------*/
 431
 432 /*
 433  * wake_worker() is used when new work is queued and when pool_resume is
 434  * ready to continue deferred IO processing.
 435  */
 436 static void wake_worker(struct pool *pool)
 437 {
 438         queue_work(pool->wq, &pool->worker);
 439 }
 440
 441 /*----------------------------------------------------------------*/
 442
 443 static int bio_detain(struct pool *pool, struct dm_cell_key *key, struct bio *bio,
 444                       struct dm_bio_prison_cell **cell_result)
 445 {
 446         int r;
 447         struct dm_bio_prison_cell *cell_prealloc;
 448
 449         /*
 450          * Allocate a cell from the prison's mempool.
 451          * This might block but it can't fail.
 452          */
 453         cell_prealloc = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);
 454
 455         r = dm_bio_detain(pool->prison, key, bio, cell_prealloc, cell_result);
 456         if (r)
 457                 /*
 458                  * We reused an old cell; we can get rid of
 459                  * the new one.
 460                  */
 461                 dm_bio_prison_free_cell(pool->prison, cell_prealloc);
 462
 463         return r;
 464 }
 465
 466 static void cell_release(struct pool *pool,
 467                          struct dm_bio_prison_cell *cell,
 468                          struct bio_list *bios)
 469 {
 470         dm_cell_release(pool->prison, cell, bios);
 471         dm_bio_prison_free_cell(pool->prison, cell);
 472 }
 473
 474 static void cell_visit_release(struct pool *pool,
 475                                void (*fn)(void *, struct dm_bio_prison_cell *),
 476                                void *context,
 477                                struct dm_bio_prison_cell *cell)
 478 {
 479         dm_cell_visit_release(pool->prison, fn, context, cell);
 480         dm_bio_prison_free_cell(pool->prison, cell);
 481 }
 482
 483 static void cell_release_no_holder(struct pool *pool,
 484                                    struct dm_bio_prison_cell *cell,
 485                                    struct bio_list *bios)
 486 {
 487         dm_cell_release_no_holder(pool->prison, cell, bios);
 488         dm_bio_prison_free_cell(pool->prison, cell);
 489 }
 490
 491 static void cell_error_with_code(struct pool *pool,
 492                 struct dm_bio_prison_cell *cell, blk_status_t error_code)
 493 {
 494         dm_cell_error(pool->prison, cell, error_code);
 495         dm_bio_prison_free_cell(pool->prison, cell);
 496 }
 497
 498 static blk_status_t get_pool_io_error_code(struct pool *pool)
 499 {
 500         return pool->out_of_data_space ? BLK_STS_NOSPC : BLK_STS_IOERR;
 501 }
 502
 503 static void cell_error(struct pool *pool, struct dm_bio_prison_cell *cell)
 504 {
 505         cell_error_with_code(pool, cell, get_pool_io_error_code(pool));
 506 }
 507
 508 static void cell_success(struct pool *pool, struct dm_bio_prison_cell *cell)
 509 {
 510         cell_error_with_code(pool, cell, 0);
 511 }
 512
 513 static void cell_requeue(struct pool *pool, struct dm_bio_prison_cell *cell)
 514 {
 515         cell_error_with_code(pool, cell, BLK_STS_DM_REQUEUE);
 516 }
 517
 518 /*----------------------------------------------------------------*/
 519
 520 /*
 521  * A global list of pools that uses a struct mapped_device as a key.
 522  */
 523 static struct dm_thin_pool_table {
 524         struct mutex mutex;
 525         struct list_head pools;
 526 } dm_thin_pool_table;
 527
 528 static void pool_table_init(void)
 529 {
 530         mutex_init(&dm_thin_pool_table.mutex);
 531         INIT_LIST_HEAD(&dm_thin_pool_table.pools);
 532 }
 533
 534 static void pool_table_exit(void)
 535 {
 536         mutex_destroy(&dm_thin_pool_table.mutex);
 537 }
 538
 539 static void __pool_table_insert(struct pool *pool)
 540 {
 541         BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 542         list_add(&pool->list, &dm_thin_pool_table.pools);
 543 }
 544
 545 static void __pool_table_remove(struct pool *pool)
 546 {
 547         BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 548         list_del(&pool->list);
 549 }
 550
 551 static struct pool *__pool_table_lookup(struct mapped_device *md)
 552 {
 553         struct pool *pool = NULL, *tmp;
 554
 555         BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 556
 557         list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
 558                 if (tmp->pool_md == md) {
 559                         pool = tmp;
 560                         break;
 561                 }
 562         }
 563
 564         return pool;
 565 }
 566
 567 static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev)
 568 {
 569         struct pool *pool = NULL, *tmp;
 570
 571         BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 572
 573         list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
 574                 if (tmp->md_dev == md_dev) {
 575                         pool = tmp;
 576                         break;
 577                 }
 578         }
 579
 580         return pool;
 581 }
 582
 583 /*----------------------------------------------------------------*/
 584
 585 struct dm_thin_endio_hook {
 586         struct thin_c *tc;
 587         struct dm_deferred_entry *shared_read_entry;
 588         struct dm_deferred_entry *all_io_entry;
 589         struct dm_thin_new_mapping *overwrite_mapping;
 590         struct rb_node rb_node;
 591         struct dm_bio_prison_cell *cell;
 592 };
 593
 594 static void __merge_bio_list(struct bio_list *bios, struct bio_list *master)
 595 {
 596         bio_list_merge(bios, master);
 597         bio_list_init(master);
 598 }
 599
 600 static void error_bio_list(struct bio_list *bios, blk_status_t error)
 601 {
 602         struct bio *bio;
 603
 604         while ((bio = bio_list_pop(bios))) {
 605                 bio->bi_status = error;
 606                 bio_endio(bio);
 607         }
 608 }
 609
 610 static void error_thin_bio_list(struct thin_c *tc, struct bio_list *master,
 611                 blk_status_t error)
 612 {
 613         struct bio_list bios;
 614
 615         bio_list_init(&bios);
 616
 617         spin_lock_irq(&tc->lock);
 618         __merge_bio_list(&bios, master);
 619         spin_unlock_irq(&tc->lock);
 620
 621         error_bio_list(&bios, error);
 622 }
 623
 624 static void requeue_deferred_cells(struct thin_c *tc)
 625 {
 626         struct pool *pool = tc->pool;
 627         struct list_head cells;
 628         struct dm_bio_prison_cell *cell, *tmp;
 629
 630         INIT_LIST_HEAD(&cells);
 631
 632         spin_lock_irq(&tc->lock);
 633         list_splice_init(&tc->deferred_cells, &cells);
 634         spin_unlock_irq(&tc->lock);
 635
 636         list_for_each_entry_safe(cell, tmp, &cells, user_list)
 637                 cell_requeue(pool, cell);
 638 }
 639
 640 static void requeue_io(struct thin_c *tc)
 641 {
 642         struct bio_list bios;
 643
 644         bio_list_init(&bios);
 645
 646         spin_lock_irq(&tc->lock);
 647         __merge_bio_list(&bios, &tc->deferred_bio_list);
 648         __merge_bio_list(&bios, &tc->retry_on_resume_list);
 649         spin_unlock_irq(&tc->lock);
 650
 651         error_bio_list(&bios, BLK_STS_DM_REQUEUE);
 652         requeue_deferred_cells(tc);
 653 }
 654
 655 static void error_retry_list_with_code(struct pool *pool, blk_status_t error)
 656 {
 657         struct thin_c *tc;
 658
 659         rcu_read_lock();
 660         list_for_each_entry_rcu(tc, &pool->active_thins, list)
 661                 error_thin_bio_list(tc, &tc->retry_on_resume_list, error);
 662         rcu_read_unlock();
 663 }
 664
 665 static void error_retry_list(struct pool *pool)
 666 {
 667         error_retry_list_with_code(pool, get_pool_io_error_code(pool));
 668 }
 669
 670 /*
 671  * This section of code contains the logic for processing a thin device's IO.
 672  * Much of the code depends on pool object resources (lists, workqueues, etc)
 673  * but most is exclusively called from the thin target rather than the thin-pool
 674  * target.
 675  */
 676
 677 static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio)
 678 {
 679         struct pool *pool = tc->pool;
 680         sector_t block_nr = bio->bi_iter.bi_sector;
 681
 682         if (block_size_is_power_of_two(pool))
 683                 block_nr >>= pool->sectors_per_block_shift;
 684         else
 685                 (void) sector_div(block_nr, pool->sectors_per_block);
 686
 687         return block_nr;
 688 }
 689
 690 /*
 691  * Returns the _complete_ blocks that this bio covers.
 692  */
 693 static void get_bio_block_range(struct thin_c *tc, struct bio *bio,
 694                                 dm_block_t *begin, dm_block_t *end)
 695 {
 696         struct pool *pool = tc->pool;
 697         sector_t b = bio->bi_iter.bi_sector;
 698         sector_t e = b + (bio->bi_iter.bi_size >> SECTOR_SHIFT);
 699
 700         b += pool->sectors_per_block - 1ull; /* so we round up */
 701
 702         if (block_size_is_power_of_two(pool)) {
 703                 b >>= pool->sectors_per_block_shift;
 704                 e >>= pool->sectors_per_block_shift;
 705         } else {
 706                 (void) sector_div(b, pool->sectors_per_block);
 707                 (void) sector_div(e, pool->sectors_per_block);
 708         }
 709
 710         if (e < b)
 711                 /* Can happen if the bio is within a single block. */
 712                 e = b;
 713
 714         *begin = b;
 715         *end = e;
 716 }
 717
 718 static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
 719 {
 720         struct pool *pool = tc->pool;
 721         sector_t bi_sector = bio->bi_iter.bi_sector;
 722
 723         bio_set_dev(bio, tc->pool_dev->bdev);
 724         if (block_size_is_power_of_two(pool))
 725                 bio->bi_iter.bi_sector =
 726                         (block << pool->sectors_per_block_shift) |
 727                         (bi_sector & (pool->sectors_per_block - 1));
 728         else
 729                 bio->bi_iter.bi_sector = (block * pool->sectors_per_block) +
 730                                  sector_div(bi_sector, pool->sectors_per_block);
 731 }
 732
 733 static void remap_to_origin(struct thin_c *tc, struct bio *bio)
 734 {
 735         bio_set_dev(bio, tc->origin_dev->bdev);
 736 }
 737
 738 static int bio_triggers_commit(struct thin_c *tc, struct bio *bio)
 739 {
 740         return op_is_flush(bio->bi_opf) &&
 741                 dm_thin_changed_this_transaction(tc->td);
 742 }
 743
 744 static void inc_all_io_entry(struct pool *pool, struct bio *bio)
 745 {
 746         struct dm_thin_endio_hook *h;
 747
 748         if (bio_op(bio) == REQ_OP_DISCARD)
 749                 return;
 750
 751         h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 752         h->all_io_entry = dm_deferred_entry_inc(pool->all_io_ds);
 753 }
 754
 755 static void issue(struct thin_c *tc, struct bio *bio)
 756 {
 757         struct pool *pool = tc->pool;
 758
 759         if (!bio_triggers_commit(tc, bio)) {
 760                 dm_submit_bio_remap(bio, NULL);
 761                 return;
 762         }
 763
 764         /*
 765          * Complete bio with an error if earlier I/O caused changes to
 766          * the metadata that can't be committed e.g, due to I/O errors
 767          * on the metadata device.
 768          */
 769         if (dm_thin_aborted_changes(tc->td)) {
 770                 bio_io_error(bio);
 771                 return;
 772         }
 773
 774         /*
 775          * Batch together any bios that trigger commits and then issue a
 776          * single commit for them in process_deferred_bios().
 777          */
 778         spin_lock_irq(&pool->lock);
 779         bio_list_add(&pool->deferred_flush_bios, bio);
 780         spin_unlock_irq(&pool->lock);
 781 }
 782
 783 static void remap_to_origin_and_issue(struct thin_c *tc, struct bio *bio)
 784 {
 785         remap_to_origin(tc, bio);
 786         issue(tc, bio);
 787 }
 788
 789 static void remap_and_issue(struct thin_c *tc, struct bio *bio,
 790                             dm_block_t block)
 791 {
 792         remap(tc, bio, block);
 793         issue(tc, bio);
 794 }
 795
 796 /*----------------------------------------------------------------*/
 797
 798 /*
 799  * Bio endio functions.
 800  */
 801 struct dm_thin_new_mapping {
 802         struct list_head list;
 803
 804         bool pass_discard:1;
 805         bool maybe_shared:1;
 806
 807         /*
 808          * Track quiescing, copying and zeroing preparation actions.  When this
 809          * counter hits zero the block is prepared and can be inserted into the
 810          * btree.
 811          */
 812         atomic_t prepare_actions;
 813
 814         blk_status_t status;
 815         struct thin_c *tc;
 816         dm_block_t virt_begin, virt_end;
 817         dm_block_t data_block;
 818         struct dm_bio_prison_cell *cell;
 819
 820         /*
 821          * If the bio covers the whole area of a block then we can avoid
 822          * zeroing or copying.  Instead this bio is hooked.  The bio will
 823          * still be in the cell, so care has to be taken to avoid issuing
 824          * the bio twice.
 825          */
 826         struct bio *bio;
 827         bio_end_io_t *saved_bi_end_io;
 828 };
 829
 830 static void __complete_mapping_preparation(struct dm_thin_new_mapping *m)
 831 {
 832         struct pool *pool = m->tc->pool;
 833
 834         if (atomic_dec_and_test(&m->prepare_actions)) {
 835                 list_add_tail(&m->list, &pool->prepared_mappings);
 836                 wake_worker(pool);
 837         }
 838 }
 839
 840 static void complete_mapping_preparation(struct dm_thin_new_mapping *m)
 841 {
 842         unsigned long flags;
 843         struct pool *pool = m->tc->pool;
 844
 845         spin_lock_irqsave(&pool->lock, flags);
 846         __complete_mapping_preparation(m);
 847         spin_unlock_irqrestore(&pool->lock, flags);
 848 }
 849
 850 static void copy_complete(int read_err, unsigned long write_err, void *context)
 851 {
 852         struct dm_thin_new_mapping *m = context;
 853
 854         m->status = read_err || write_err ? BLK_STS_IOERR : 0;
 855         complete_mapping_preparation(m);
 856 }
 857
 858 static void overwrite_endio(struct bio *bio)
 859 {
 860         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 861         struct dm_thin_new_mapping *m = h->overwrite_mapping;
 862
 863         bio->bi_end_io = m->saved_bi_end_io;
 864
 865         m->status = bio->bi_status;
 866         complete_mapping_preparation(m);
 867 }
 868
 869 /*----------------------------------------------------------------*/
 870
 871 /*
 872  * Workqueue.
 873  */
 874
 875 /*
 876  * Prepared mapping jobs.
 877  */
 878
 879 /*
 880  * This sends the bios in the cell, except the original holder, back
 881  * to the deferred_bios list.
 882  */
 883 static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
 884 {
 885         struct pool *pool = tc->pool;
 886         unsigned long flags;
 887         struct bio_list bios;
 888
 889         bio_list_init(&bios);
 890         cell_release_no_holder(pool, cell, &bios);
 891
 892         if (!bio_list_empty(&bios)) {
 893                 spin_lock_irqsave(&tc->lock, flags);
 894                 bio_list_merge(&tc->deferred_bio_list, &bios);
 895                 spin_unlock_irqrestore(&tc->lock, flags);
 896                 wake_worker(pool);
 897         }
 898 }
 899
 900 static void thin_defer_bio(struct thin_c *tc, struct bio *bio);
 901
 902 struct remap_info {
 903         struct thin_c *tc;
 904         struct bio_list defer_bios;
 905         struct bio_list issue_bios;
 906 };
 907
 908 static void __inc_remap_and_issue_cell(void *context,
 909                                        struct dm_bio_prison_cell *cell)
 910 {
 911         struct remap_info *info = context;
 912         struct bio *bio;
 913
 914         while ((bio = bio_list_pop(&cell->bios))) {
 915                 if (op_is_flush(bio->bi_opf) || bio_op(bio) == REQ_OP_DISCARD)
 916                         bio_list_add(&info->defer_bios, bio);
 917                 else {
 918                         inc_all_io_entry(info->tc->pool, bio);
 919
 920                         /*
 921                          * We can't issue the bios with the bio prison lock
 922                          * held, so we add them to a list to issue on
 923                          * return from this function.
 924                          */
 925                         bio_list_add(&info->issue_bios, bio);
 926                 }
 927         }
 928 }
 929
 930 static void inc_remap_and_issue_cell(struct thin_c *tc,
 931                                      struct dm_bio_prison_cell *cell,
 932                                      dm_block_t block)
 933 {
 934         struct bio *bio;
 935         struct remap_info info;
 936
 937         info.tc = tc;
 938         bio_list_init(&info.defer_bios);
 939         bio_list_init(&info.issue_bios);
 940
 941         /*
 942          * We have to be careful to inc any bios we're about to issue
 943          * before the cell is released, and avoid a race with new bios
 944          * being added to the cell.
 945          */
 946         cell_visit_release(tc->pool, __inc_remap_and_issue_cell,
 947                            &info, cell);
 948
 949         while ((bio = bio_list_pop(&info.defer_bios)))
 950                 thin_defer_bio(tc, bio);
 951
 952         while ((bio = bio_list_pop(&info.issue_bios)))
 953                 remap_and_issue(info.tc, bio, block);
 954 }
 955
 956 static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
 957 {
 958         cell_error(m->tc->pool, m->cell);
 959         list_del(&m->list);
 960         mempool_free(m, &m->tc->pool->mapping_pool);
 961 }
 962
 963 static void complete_overwrite_bio(struct thin_c *tc, struct bio *bio)
 964 {
 965         struct pool *pool = tc->pool;
 966
 967         /*
 968          * If the bio has the REQ_FUA flag set we must commit the metadata
 969          * before signaling its completion.
 970          */
 971         if (!bio_triggers_commit(tc, bio)) {
 972                 bio_endio(bio);
 973                 return;
 974         }
 975
 976         /*
 977          * Complete bio with an error if earlier I/O caused changes to the
 978          * metadata that can't be committed, e.g, due to I/O errors on the
 979          * metadata device.
 980          */
 981         if (dm_thin_aborted_changes(tc->td)) {
 982                 bio_io_error(bio);
 983                 return;
 984         }
 985
 986         /*
 987          * Batch together any bios that trigger commits and then issue a
 988          * single commit for them in process_deferred_bios().
 989          */
 990         spin_lock_irq(&pool->lock);
 991         bio_list_add(&pool->deferred_flush_completions, bio);
 992         spin_unlock_irq(&pool->lock);
 993 }
 994
 995 static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 996 {
 997         struct thin_c *tc = m->tc;
 998         struct pool *pool = tc->pool;
 999         struct bio *bio = m->bio;
1000         int r;
1001
1002         if (m->status) {
1003                 cell_error(pool, m->cell);
1004                 goto out;
1005         }
1006
1007         /*
1008          * Commit the prepared block into the mapping btree.
1009          * Any I/O for this block arriving after this point will get
1010          * remapped to it directly.
1011          */
1012         r = dm_thin_insert_block(tc->td, m->virt_begin, m->data_block);
1013         if (r) {
1014                 metadata_operation_failed(pool, "dm_thin_insert_block", r);
1015                 cell_error(pool, m->cell);
1016                 goto out;
1017         }
1018
1019         /*
1020          * Release any bios held while the block was being provisioned.
1021          * If we are processing a write bio that completely covers the block,
1022          * we already processed it so can ignore it now when processing
1023          * the bios in the cell.
1024          */
1025         if (bio) {
1026                 inc_remap_and_issue_cell(tc, m->cell, m->data_block);
1027                 complete_overwrite_bio(tc, bio);
1028         } else {
1029                 inc_all_io_entry(tc->pool, m->cell->holder);
1030                 remap_and_issue(tc, m->cell->holder, m->data_block);
1031                 inc_remap_and_issue_cell(tc, m->cell, m->data_block);
1032         }
1033
1034 out:
1035         list_del(&m->list);
1036         mempool_free(m, &pool->mapping_pool);
1037 }
1038
1039 /*----------------------------------------------------------------*/
1040
1041 static void free_discard_mapping(struct dm_thin_new_mapping *m)
1042 {
1043         struct thin_c *tc = m->tc;
1044
1045         if (m->cell)
1046                 cell_defer_no_holder(tc, m->cell);
1047         mempool_free(m, &tc->pool->mapping_pool);
1048 }
1049
1050 static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
1051 {
1052         bio_io_error(m->bio);
1053         free_discard_mapping(m);
1054 }
1055
1056 static void process_prepared_discard_success(struct dm_thin_new_mapping *m)
1057 {
1058         bio_endio(m->bio);
1059         free_discard_mapping(m);
1060 }
1061
1062 static void process_prepared_discard_no_passdown(struct dm_thin_new_mapping *m)
1063 {
1064         int r;
1065         struct thin_c *tc = m->tc;
1066
1067         r = dm_thin_remove_range(tc->td, m->cell->key.block_begin, m->cell->key.block_end);
1068         if (r) {
1069                 metadata_operation_failed(tc->pool, "dm_thin_remove_range", r);
1070                 bio_io_error(m->bio);
1071         } else
1072                 bio_endio(m->bio);
1073
1074         cell_defer_no_holder(tc, m->cell);
1075         mempool_free(m, &tc->pool->mapping_pool);
1076 }
1077
1078 /*----------------------------------------------------------------*/
1079
1080 static void passdown_double_checking_shared_status(struct dm_thin_new_mapping *m,
1081                                                    struct bio *discard_parent)
1082 {
1083         /*
1084          * We've already unmapped this range of blocks, but before we
1085          * passdown we have to check that these blocks are now unused.
1086          */
1087         int r = 0;
1088         bool shared = true;
1089         struct thin_c *tc = m->tc;
1090         struct pool *pool = tc->pool;
1091         dm_block_t b = m->data_block, e, end = m->data_block + m->virt_end - m->virt_begin;
1092         struct discard_op op;
1093
1094         begin_discard(&op, tc, discard_parent);
1095         while (b != end) {
1096                 /* find start of unmapped run */
1097                 for (; b < end; b++) {
1098                         r = dm_pool_block_is_shared(pool->pmd, b, &shared);
1099                         if (r)
1100                                 goto out;
1101
1102                         if (!shared)
1103                                 break;
1104                 }
1105
1106                 if (b == end)
1107                         break;
1108
1109                 /* find end of run */
1110                 for (e = b + 1; e != end; e++) {
1111                         r = dm_pool_block_is_shared(pool->pmd, e, &shared);
1112                         if (r)
1113                                 goto out;
1114
1115                         if (shared)
1116                                 break;
1117                 }
1118
1119                 r = issue_discard(&op, b, e);
1120                 if (r)
1121                         goto out;
1122
1123                 b = e;
1124         }
1125 out:
1126         end_discard(&op, r);
1127 }
1128
1129 static void queue_passdown_pt2(struct dm_thin_new_mapping *m)
1130 {
1131         unsigned long flags;
1132         struct pool *pool = m->tc->pool;
1133
1134         spin_lock_irqsave(&pool->lock, flags);
1135         list_add_tail(&m->list, &pool->prepared_discards_pt2);
1136         spin_unlock_irqrestore(&pool->lock, flags);
1137         wake_worker(pool);
1138 }
1139
1140 static void passdown_endio(struct bio *bio)
1141 {
1142         /*
1143          * It doesn't matter if the passdown discard failed, we still want
1144          * to unmap (we ignore err).
1145          */
1146         queue_passdown_pt2(bio->bi_private);
1147         bio_put(bio);
1148 }
1149
1150 static void process_prepared_discard_passdown_pt1(struct dm_thin_new_mapping *m)
1151 {
1152         int r;
1153         struct thin_c *tc = m->tc;
1154         struct pool *pool = tc->pool;
1155         struct bio *discard_parent;
1156         dm_block_t data_end = m->data_block + (m->virt_end - m->virt_begin);
1157
1158         /*
1159          * Only this thread allocates blocks, so we can be sure that the
1160          * newly unmapped blocks will not be allocated before the end of
1161          * the function.
1162          */
1163         r = dm_thin_remove_range(tc->td, m->virt_begin, m->virt_end);
1164         if (r) {
1165                 metadata_operation_failed(pool, "dm_thin_remove_range", r);
1166                 bio_io_error(m->bio);
1167                 cell_defer_no_holder(tc, m->cell);
1168                 mempool_free(m, &pool->mapping_pool);
1169                 return;
1170         }
1171
1172         /*
1173          * Increment the unmapped blocks.  This prevents a race between the
1174          * passdown io and reallocation of freed blocks.
1175          */
1176         r = dm_pool_inc_data_range(pool->pmd, m->data_block, data_end);
1177         if (r) {
1178                 metadata_operation_failed(pool, "dm_pool_inc_data_range", r);
1179                 bio_io_error(m->bio);
1180                 cell_defer_no_holder(tc, m->cell);
1181                 mempool_free(m, &pool->mapping_pool);
1182                 return;
1183         }
1184
1185         discard_parent = bio_alloc(NULL, 1, 0, GFP_NOIO);
1186         discard_parent->bi_end_io = passdown_endio;
1187         discard_parent->bi_private = m;
1188         if (m->maybe_shared)
1189                 passdown_double_checking_shared_status(m, discard_parent);
1190         else {
1191                 struct discard_op op;
1192
1193                 begin_discard(&op, tc, discard_parent);
1194                 r = issue_discard(&op, m->data_block, data_end);
1195                 end_discard(&op, r);
1196         }
1197 }
1198
1199 static void process_prepared_discard_passdown_pt2(struct dm_thin_new_mapping *m)
1200 {
1201         int r;
1202         struct thin_c *tc = m->tc;
1203         struct pool *pool = tc->pool;
1204
1205         /*
1206          * The passdown has completed, so now we can decrement all those
1207          * unmapped blocks.
1208          */
1209         r = dm_pool_dec_data_range(pool->pmd, m->data_block,
1210                                    m->data_block + (m->virt_end - m->virt_begin));
1211         if (r) {
1212                 metadata_operation_failed(pool, "dm_pool_dec_data_range", r);
1213                 bio_io_error(m->bio);
1214         } else
1215                 bio_endio(m->bio);
1216
1217         cell_defer_no_holder(tc, m->cell);
1218         mempool_free(m, &pool->mapping_pool);
1219 }
1220
1221 static void process_prepared(struct pool *pool, struct list_head *head,
1222                              process_mapping_fn *fn)
1223 {
1224         struct list_head maps;
1225         struct dm_thin_new_mapping *m, *tmp;
1226
1227         INIT_LIST_HEAD(&maps);
1228         spin_lock_irq(&pool->lock);
1229         list_splice_init(head, &maps);
1230         spin_unlock_irq(&pool->lock);
1231
1232         list_for_each_entry_safe(m, tmp, &maps, list)
1233                 (*fn)(m);
1234 }
1235
1236 /*
1237  * Deferred bio jobs.
1238  */
1239 static int io_overlaps_block(struct pool *pool, struct bio *bio)
1240 {
1241         return bio->bi_iter.bi_size ==
1242                 (pool->sectors_per_block << SECTOR_SHIFT);
1243 }
1244
1245 static int io_overwrites_block(struct pool *pool, struct bio *bio)
1246 {
1247         return (bio_data_dir(bio) == WRITE) &&
1248                 io_overlaps_block(pool, bio);
1249 }
1250
1251 static void save_and_set_endio(struct bio *bio, bio_end_io_t **save,
1252                                bio_end_io_t *fn)
1253 {
1254         *save = bio->bi_end_io;
1255         bio->bi_end_io = fn;
1256 }
1257
1258 static int ensure_next_mapping(struct pool *pool)
1259 {
1260         if (pool->next_mapping)
1261                 return 0;
1262
1263         pool->next_mapping = mempool_alloc(&pool->mapping_pool, GFP_ATOMIC);
1264
1265         return pool->next_mapping ? 0 : -ENOMEM;
1266 }
1267
1268 static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool)
1269 {
1270         struct dm_thin_new_mapping *m = pool->next_mapping;
1271
1272         BUG_ON(!pool->next_mapping);
1273
1274         memset(m, 0, sizeof(struct dm_thin_new_mapping));
1275         INIT_LIST_HEAD(&m->list);
1276         m->bio = NULL;
1277
1278         pool->next_mapping = NULL;
1279
1280         return m;
1281 }
1282
1283 static void ll_zero(struct thin_c *tc, struct dm_thin_new_mapping *m,
1284                     sector_t begin, sector_t end)
1285 {
1286         struct dm_io_region to;
1287
1288         to.bdev = tc->pool_dev->bdev;
1289         to.sector = begin;
1290         to.count = end - begin;
1291
1292         dm_kcopyd_zero(tc->pool->copier, 1, &to, 0, copy_complete, m);
1293 }
1294
1295 static void remap_and_issue_overwrite(struct thin_c *tc, struct bio *bio,
1296                                       dm_block_t data_begin,
1297                                       struct dm_thin_new_mapping *m)
1298 {
1299         struct pool *pool = tc->pool;
1300         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1301
1302         h->overwrite_mapping = m;
1303         m->bio = bio;
1304         save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
1305         inc_all_io_entry(pool, bio);
1306         remap_and_issue(tc, bio, data_begin);
1307 }
1308
1309 /*
1310  * A partial copy also needs to zero the uncopied region.
1311  */
1312 static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
1313                           struct dm_dev *origin, dm_block_t data_origin,
1314                           dm_block_t data_dest,
1315                           struct dm_bio_prison_cell *cell, struct bio *bio,
1316                           sector_t len)
1317 {
1318         struct pool *pool = tc->pool;
1319         struct dm_thin_new_mapping *m = get_next_mapping(pool);
1320
1321         m->tc = tc;
1322         m->virt_begin = virt_block;
1323         m->virt_end = virt_block + 1u;
1324         m->data_block = data_dest;
1325         m->cell = cell;
1326
1327         /*
1328          * quiesce action + copy action + an extra reference held for the
1329          * duration of this function (we may need to inc later for a
1330          * partial zero).
1331          */
1332         atomic_set(&m->prepare_actions, 3);
1333
1334         if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
1335                 complete_mapping_preparation(m); /* already quiesced */
1336
1337         /*
1338          * IO to pool_dev remaps to the pool target's data_dev.
1339          *
1340          * If the whole block of data is being overwritten, we can issue the
1341          * bio immediately. Otherwise we use kcopyd to clone the data first.
1342          */
1343         if (io_overwrites_block(pool, bio))
1344                 remap_and_issue_overwrite(tc, bio, data_dest, m);
1345         else {
1346                 struct dm_io_region from, to;
1347
1348                 from.bdev = origin->bdev;
1349                 from.sector = data_origin * pool->sectors_per_block;
1350                 from.count = len;
1351
1352                 to.bdev = tc->pool_dev->bdev;
1353                 to.sector = data_dest * pool->sectors_per_block;
1354                 to.count = len;
1355
1356                 dm_kcopyd_copy(pool->copier, &from, 1, &to,
1357                                0, copy_complete, m);
1358
1359                 /*
1360                  * Do we need to zero a tail region?
1361                  */
1362                 if (len < pool->sectors_per_block && pool->pf.zero_new_blocks) {
1363                         atomic_inc(&m->prepare_actions);
1364                         ll_zero(tc, m,
1365                                 data_dest * pool->sectors_per_block + len,
1366                                 (data_dest + 1) * pool->sectors_per_block);
1367                 }
1368         }
1369
1370         complete_mapping_preparation(m); /* drop our ref */
1371 }
1372
1373 static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,
1374                                    dm_block_t data_origin, dm_block_t data_dest,
1375                                    struct dm_bio_prison_cell *cell, struct bio *bio)
1376 {
1377         schedule_copy(tc, virt_block, tc->pool_dev,
1378                       data_origin, data_dest, cell, bio,
1379                       tc->pool->sectors_per_block);
1380 }
1381
1382 static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
1383                           dm_block_t data_block, struct dm_bio_prison_cell *cell,
1384                           struct bio *bio)
1385 {
1386         struct pool *pool = tc->pool;
1387         struct dm_thin_new_mapping *m = get_next_mapping(pool);
1388
1389         atomic_set(&m->prepare_actions, 1); /* no need to quiesce */
1390         m->tc = tc;
1391         m->virt_begin = virt_block;
1392         m->virt_end = virt_block + 1u;
1393         m->data_block = data_block;
1394         m->cell = cell;
1395
1396         /*
1397          * If the whole block of data is being overwritten or we are not
1398          * zeroing pre-existing data, we can issue the bio immediately.
1399          * Otherwise we use kcopyd to zero the data first.
1400          */
1401         if (pool->pf.zero_new_blocks) {
1402                 if (io_overwrites_block(pool, bio))
1403                         remap_and_issue_overwrite(tc, bio, data_block, m);
1404                 else
1405                         ll_zero(tc, m, data_block * pool->sectors_per_block,
1406                                 (data_block + 1) * pool->sectors_per_block);
1407         } else
1408                 process_prepared_mapping(m);
1409 }
1410
1411 static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,
1412                                    dm_block_t data_dest,
1413                                    struct dm_bio_prison_cell *cell, struct bio *bio)
1414 {
1415         struct pool *pool = tc->pool;
1416         sector_t virt_block_begin = virt_block * pool->sectors_per_block;
1417         sector_t virt_block_end = (virt_block + 1) * pool->sectors_per_block;
1418
1419         if (virt_block_end <= tc->origin_size)
1420                 schedule_copy(tc, virt_block, tc->origin_dev,
1421                               virt_block, data_dest, cell, bio,
1422                               pool->sectors_per_block);
1423
1424         else if (virt_block_begin < tc->origin_size)
1425                 schedule_copy(tc, virt_block, tc->origin_dev,
1426                               virt_block, data_dest, cell, bio,
1427                               tc->origin_size - virt_block_begin);
1428
1429         else
1430                 schedule_zero(tc, virt_block, data_dest, cell, bio);
1431 }
1432
1433 static void set_pool_mode(struct pool *pool, enum pool_mode new_mode);
1434
1435 static void requeue_bios(struct pool *pool);
1436
1437 static bool is_read_only_pool_mode(enum pool_mode mode)
1438 {
1439         return (mode == PM_OUT_OF_METADATA_SPACE || mode == PM_READ_ONLY);
1440 }
1441
1442 static bool is_read_only(struct pool *pool)
1443 {
1444         return is_read_only_pool_mode(get_pool_mode(pool));
1445 }
1446
1447 static void check_for_metadata_space(struct pool *pool)
1448 {
1449         int r;
1450         const char *ooms_reason = NULL;
1451         dm_block_t nr_free;
1452
1453         r = dm_pool_get_free_metadata_block_count(pool->pmd, &nr_free);
1454         if (r)
1455                 ooms_reason = "Could not get free metadata blocks";
1456         else if (!nr_free)
1457                 ooms_reason = "No free metadata blocks";
1458
1459         if (ooms_reason && !is_read_only(pool)) {
1460                 DMERR("%s", ooms_reason);
1461                 set_pool_mode(pool, PM_OUT_OF_METADATA_SPACE);
1462         }
1463 }
1464
1465 static void check_for_data_space(struct pool *pool)
1466 {
1467         int r;
1468         dm_block_t nr_free;
1469
1470         if (get_pool_mode(pool) != PM_OUT_OF_DATA_SPACE)
1471                 return;
1472
1473         r = dm_pool_get_free_block_count(pool->pmd, &nr_free);
1474         if (r)
1475                 return;
1476
1477         if (nr_free) {
1478                 set_pool_mode(pool, PM_WRITE);
1479                 requeue_bios(pool);
1480         }
1481 }
1482
1483 /*
1484  * A non-zero return indicates read_only or fail_io mode.
1485  * Many callers don't care about the return value.
1486  */
1487 static int commit(struct pool *pool)
1488 {
1489         int r;
1490
1491         if (get_pool_mode(pool) >= PM_OUT_OF_METADATA_SPACE)
1492                 return -EINVAL;
1493
1494         r = dm_pool_commit_metadata(pool->pmd);
1495         if (r)
1496                 metadata_operation_failed(pool, "dm_pool_commit_metadata", r);
1497         else {
1498                 check_for_metadata_space(pool);
1499                 check_for_data_space(pool);
1500         }
1501
1502         return r;
1503 }
1504
1505 static void check_low_water_mark(struct pool *pool, dm_block_t free_blocks)
1506 {
1507         if (free_blocks <= pool->low_water_blocks && !pool->low_water_triggered) {
1508                 DMWARN("%s: reached low water mark for data device: sending event.",
1509                        dm_device_name(pool->pool_md));
1510                 spin_lock_irq(&pool->lock);
1511                 pool->low_water_triggered = true;
1512                 spin_unlock_irq(&pool->lock);
1513                 dm_table_event(pool->ti->table);
1514         }
1515 }
1516
1517 static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
1518 {
1519         int r;
1520         dm_block_t free_blocks;
1521         struct pool *pool = tc->pool;
1522
1523         if (WARN_ON(get_pool_mode(pool) != PM_WRITE))
1524                 return -EINVAL;
1525
1526         r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
1527         if (r) {
1528                 metadata_operation_failed(pool, "dm_pool_get_free_block_count", r);
1529                 return r;
1530         }
1531
1532         check_low_water_mark(pool, free_blocks);
1533
1534         if (!free_blocks) {
1535                 /*
1536                  * Try to commit to see if that will free up some
1537                  * more space.
1538                  */
1539                 r = commit(pool);
1540                 if (r)
1541                         return r;
1542
1543                 r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
1544                 if (r) {
1545                         metadata_operation_failed(pool, "dm_pool_get_free_block_count", r);
1546                         return r;
1547                 }
1548
1549                 if (!free_blocks) {
1550                         set_pool_mode(pool, PM_OUT_OF_DATA_SPACE);
1551                         return -ENOSPC;
1552                 }
1553         }
1554
1555         r = dm_pool_alloc_data_block(pool->pmd, result);
1556         if (r) {
1557                 if (r == -ENOSPC)
1558                         set_pool_mode(pool, PM_OUT_OF_DATA_SPACE);
1559                 else
1560                         metadata_operation_failed(pool, "dm_pool_alloc_data_block", r);
1561                 return r;
1562         }
1563
1564         r = dm_pool_get_free_metadata_block_count(pool->pmd, &free_blocks);
1565         if (r) {
1566                 metadata_operation_failed(pool, "dm_pool_get_free_metadata_block_count", r);
1567                 return r;
1568         }
1569
1570         if (!free_blocks) {
1571                 /* Let's commit before we use up the metadata reserve. */
1572                 r = commit(pool);
1573                 if (r)
1574                         return r;
1575         }
1576
1577         return 0;
1578 }
1579
1580 /*
1581  * If we have run out of space, queue bios until the device is
1582  * resumed, presumably after having been reloaded with more space.
1583  */
1584 static void retry_on_resume(struct bio *bio)
1585 {
1586         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1587         struct thin_c *tc = h->tc;
1588
1589         spin_lock_irq(&tc->lock);
1590         bio_list_add(&tc->retry_on_resume_list, bio);
1591         spin_unlock_irq(&tc->lock);
1592 }
1593
1594 static blk_status_t should_error_unserviceable_bio(struct pool *pool)
1595 {
1596         enum pool_mode m = get_pool_mode(pool);
1597
1598         switch (m) {
1599         case PM_WRITE:
1600                 /* Shouldn't get here */
1601                 DMERR_LIMIT("bio unserviceable, yet pool is in PM_WRITE mode");
1602                 return BLK_STS_IOERR;
1603
1604         case PM_OUT_OF_DATA_SPACE:
1605                 return pool->pf.error_if_no_space ? BLK_STS_NOSPC : 0;
1606
1607         case PM_OUT_OF_METADATA_SPACE:
1608         case PM_READ_ONLY:
1609         case PM_FAIL:
1610                 return BLK_STS_IOERR;
1611         default:
1612                 /* Shouldn't get here */
1613                 DMERR_LIMIT("bio unserviceable, yet pool has an unknown mode");
1614                 return BLK_STS_IOERR;
1615         }
1616 }
1617
1618 static void handle_unserviceable_bio(struct pool *pool, struct bio *bio)
1619 {
1620         blk_status_t error = should_error_unserviceable_bio(pool);
1621
1622         if (error) {
1623                 bio->bi_status = error;
1624                 bio_endio(bio);
1625         } else
1626                 retry_on_resume(bio);
1627 }
1628
1629 static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *cell)
1630 {
1631         struct bio *bio;
1632         struct bio_list bios;
1633         blk_status_t error;
1634
1635         error = should_error_unserviceable_bio(pool);
1636         if (error) {
1637                 cell_error_with_code(pool, cell, error);
1638                 return;
1639         }
1640
1641         bio_list_init(&bios);
1642         cell_release(pool, cell, &bios);
1643
1644         while ((bio = bio_list_pop(&bios)))
1645                 retry_on_resume(bio);
1646 }
1647
1648 static void process_discard_cell_no_passdown(struct thin_c *tc,
1649                                              struct dm_bio_prison_cell *virt_cell)
1650 {
1651         struct pool *pool = tc->pool;
1652         struct dm_thin_new_mapping *m = get_next_mapping(pool);
1653
1654         /*
1655          * We don't need to lock the data blocks, since there's no
1656          * passdown.  We only lock data blocks for allocation and breaking sharing.
1657          */
1658         m->tc = tc;
1659         m->virt_begin = virt_cell->key.block_begin;
1660         m->virt_end = virt_cell->key.block_end;
1661         m->cell = virt_cell;
1662         m->bio = virt_cell->holder;
1663
1664         if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list))
1665                 pool->process_prepared_discard(m);
1666 }
1667
1668 static void break_up_discard_bio(struct thin_c *tc, dm_block_t begin, dm_block_t end,
1669                                  struct bio *bio)
1670 {
1671         struct pool *pool = tc->pool;
1672
1673         int r;
1674         bool maybe_shared;
1675         struct dm_cell_key data_key;
1676         struct dm_bio_prison_cell *data_cell;
1677         struct dm_thin_new_mapping *m;
1678         dm_block_t virt_begin, virt_end, data_begin, data_end;
1679         dm_block_t len, next_boundary;
1680
1681         while (begin != end) {
1682                 r = dm_thin_find_mapped_range(tc->td, begin, end, &virt_begin, &virt_end,
1683                                               &data_begin, &maybe_shared);
1684                 if (r) {
1685                         /*
1686                          * Silently fail, letting any mappings we've
1687                          * created complete.
1688                          */
1689                         break;
1690                 }
1691
1692                 data_end = data_begin + (virt_end - virt_begin);
1693
1694                 /*
1695                  * Make sure the data region obeys the bio prison restrictions.
1696                  */
1697                 while (data_begin < data_end) {
1698                         r = ensure_next_mapping(pool);
1699                         if (r)
1700                                 return; /* we did our best */
1701
1702                         next_boundary = ((data_begin >> BIO_PRISON_MAX_RANGE_SHIFT) + 1)
1703                                 << BIO_PRISON_MAX_RANGE_SHIFT;
1704                         len = min_t(sector_t, data_end - data_begin, next_boundary - data_begin);
1705
1706                         /* This key is certainly within range given the above splitting */
1707                         (void) build_key(tc->td, PHYSICAL, data_begin, data_begin + len, &data_key);
1708                         if (bio_detain(tc->pool, &data_key, NULL, &data_cell)) {
1709                                 /* contention, we'll give up with this range */
1710                                 data_begin += len;
1711                                 continue;
1712                         }
1713
1714                         /*
1715                          * IO may still be going to the destination block.  We must
1716                          * quiesce before we can do the removal.
1717                          */
1718                         m = get_next_mapping(pool);
1719                         m->tc = tc;
1720                         m->maybe_shared = maybe_shared;
1721                         m->virt_begin = virt_begin;
1722                         m->virt_end = virt_begin + len;
1723                         m->data_block = data_begin;
1724                         m->cell = data_cell;
1725                         m->bio = bio;
1726
1727                         /*
1728                          * The parent bio must not complete before sub discard bios are
1729                          * chained to it (see end_discard's bio_chain)!
1730                          *
1731                          * This per-mapping bi_remaining increment is paired with
1732                          * the implicit decrement that occurs via bio_endio() in
1733                          * end_discard().
1734                          */
1735                         bio_inc_remaining(bio);
1736                         if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list))
1737                                 pool->process_prepared_discard(m);
1738
1739                         virt_begin += len;
1740                         data_begin += len;
1741                 }
1742
1743                 begin = virt_end;
1744         }
1745 }
1746
1747 static void process_discard_cell_passdown(struct thin_c *tc, struct dm_bio_prison_cell *virt_cell)
1748 {
1749         struct bio *bio = virt_cell->holder;
1750         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1751
1752         /*
1753          * The virt_cell will only get freed once the origin bio completes.
1754          * This means it will remain locked while all the individual
1755          * passdown bios are in flight.
1756          */
1757         h->cell = virt_cell;
1758         break_up_discard_bio(tc, virt_cell->key.block_begin, virt_cell->key.block_end, bio);
1759
1760         /*
1761          * We complete the bio now, knowing that the bi_remaining field
1762          * will prevent completion until the sub range discards have
1763          * completed.
1764          */
1765         bio_endio(bio);
1766 }
1767
1768 static void process_discard_bio(struct thin_c *tc, struct bio *bio)
1769 {
1770         dm_block_t begin, end;
1771         struct dm_cell_key virt_key;
1772         struct dm_bio_prison_cell *virt_cell;
1773
1774         get_bio_block_range(tc, bio, &begin, &end);
1775         if (begin == end) {
1776                 /*
1777                  * The discard covers less than a block.
1778                  */
1779                 bio_endio(bio);
1780                 return;
1781         }
1782
1783         if (unlikely(!build_key(tc->td, VIRTUAL, begin, end, &virt_key))) {
1784                 DMERR_LIMIT("Discard doesn't respect bio prison limits");
1785                 bio_endio(bio);
1786                 return;
1787         }
1788
1789         if (bio_detain(tc->pool, &virt_key, bio, &virt_cell)) {
1790                 /*
1791                  * Potential starvation issue: We're relying on the
1792                  * fs/application being well behaved, and not trying to
1793                  * send IO to a region at the same time as discarding it.
1794                  * If they do this persistently then it's possible this
1795                  * cell will never be granted.
1796                  */
1797                 return;
1798         }
1799
1800         tc->pool->process_discard_cell(tc, virt_cell);
1801 }
1802
1803 static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
1804                           struct dm_cell_key *key,
1805                           struct dm_thin_lookup_result *lookup_result,
1806                           struct dm_bio_prison_cell *cell)
1807 {
1808         int r;
1809         dm_block_t data_block;
1810         struct pool *pool = tc->pool;
1811
1812         r = alloc_data_block(tc, &data_block);
1813         switch (r) {
1814         case 0:
1815                 schedule_internal_copy(tc, block, lookup_result->block,
1816                                        data_block, cell, bio);
1817                 break;
1818
1819         case -ENOSPC:
1820                 retry_bios_on_resume(pool, cell);
1821                 break;
1822
1823         default:
1824                 DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
1825                             __func__, r);
1826                 cell_error(pool, cell);
1827                 break;
1828         }
1829 }
1830
1831 static void __remap_and_issue_shared_cell(void *context,
1832                                           struct dm_bio_prison_cell *cell)
1833 {
1834         struct remap_info *info = context;
1835         struct bio *bio;
1836
1837         while ((bio = bio_list_pop(&cell->bios))) {
1838                 if (bio_data_dir(bio) == WRITE || op_is_flush(bio->bi_opf) ||
1839                     bio_op(bio) == REQ_OP_DISCARD)
1840                         bio_list_add(&info->defer_bios, bio);
1841                 else {
1842                         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1843
1844                         h->shared_read_entry = dm_deferred_entry_inc(info->tc->pool->shared_read_ds);
1845                         inc_all_io_entry(info->tc->pool, bio);
1846                         bio_list_add(&info->issue_bios, bio);
1847                 }
1848         }
1849 }
1850
1851 static void remap_and_issue_shared_cell(struct thin_c *tc,
1852                                         struct dm_bio_prison_cell *cell,
1853                                         dm_block_t block)
1854 {
1855         struct bio *bio;
1856         struct remap_info info;
1857
1858         info.tc = tc;
1859         bio_list_init(&info.defer_bios);
1860         bio_list_init(&info.issue_bios);
1861
1862         cell_visit_release(tc->pool, __remap_and_issue_shared_cell,
1863                            &info, cell);
1864
1865         while ((bio = bio_list_pop(&info.defer_bios)))
1866                 thin_defer_bio(tc, bio);
1867
1868         while ((bio = bio_list_pop(&info.issue_bios)))
1869                 remap_and_issue(tc, bio, block);
1870 }
1871
1872 static void process_shared_bio(struct thin_c *tc, struct bio *bio,
1873                                dm_block_t block,
1874                                struct dm_thin_lookup_result *lookup_result,
1875                                struct dm_bio_prison_cell *virt_cell)
1876 {
1877         struct dm_bio_prison_cell *data_cell;
1878         struct pool *pool = tc->pool;
1879         struct dm_cell_key key;
1880
1881         /*
1882          * If cell is already occupied, then sharing is already in the process
1883          * of being broken so we have nothing further to do here.
1884          */
1885         build_data_key(tc->td, lookup_result->block, &key);
1886         if (bio_detain(pool, &key, bio, &data_cell)) {
1887                 cell_defer_no_holder(tc, virt_cell);
1888                 return;
1889         }
1890
1891         if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size) {
1892                 break_sharing(tc, bio, block, &key, lookup_result, data_cell);
1893                 cell_defer_no_holder(tc, virt_cell);
1894         } else {
1895                 struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1896
1897                 h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
1898                 inc_all_io_entry(pool, bio);
1899                 remap_and_issue(tc, bio, lookup_result->block);
1900
1901                 remap_and_issue_shared_cell(tc, data_cell, lookup_result->block);
1902                 remap_and_issue_shared_cell(tc, virt_cell, lookup_result->block);
1903         }
1904 }
1905
1906 static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block,
1907                             struct dm_bio_prison_cell *cell)
1908 {
1909         int r;
1910         dm_block_t data_block;
1911         struct pool *pool = tc->pool;
1912
1913         /*
1914          * Remap empty bios (flushes) immediately, without provisioning.
1915          */
1916         if (!bio->bi_iter.bi_size) {
1917                 inc_all_io_entry(pool, bio);
1918                 cell_defer_no_holder(tc, cell);
1919
1920                 remap_and_issue(tc, bio, 0);
1921                 return;
1922         }
1923
1924         /*
1925          * Fill read bios with zeroes and complete them immediately.
1926          */
1927         if (bio_data_dir(bio) == READ) {
1928                 zero_fill_bio(bio);
1929                 cell_defer_no_holder(tc, cell);
1930                 bio_endio(bio);
1931                 return;
1932         }
1933
1934         r = alloc_data_block(tc, &data_block);
1935         switch (r) {
1936         case 0:
1937                 if (tc->origin_dev)
1938                         schedule_external_copy(tc, block, data_block, cell, bio);
1939                 else
1940                         schedule_zero(tc, block, data_block, cell, bio);
1941                 break;
1942
1943         case -ENOSPC:
1944                 retry_bios_on_resume(pool, cell);
1945                 break;
1946
1947         default:
1948                 DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
1949                             __func__, r);
1950                 cell_error(pool, cell);
1951                 break;
1952         }
1953 }
1954
1955 static void process_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
1956 {
1957         int r;
1958         struct pool *pool = tc->pool;
1959         struct bio *bio = cell->holder;
1960         dm_block_t block = get_bio_block(tc, bio);
1961         struct dm_thin_lookup_result lookup_result;
1962
1963         if (tc->requeue_mode) {
1964                 cell_requeue(pool, cell);
1965                 return;
1966         }
1967
1968         r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
1969         switch (r) {
1970         case 0:
1971                 if (lookup_result.shared)
1972                         process_shared_bio(tc, bio, block, &lookup_result, cell);
1973                 else {
1974                         inc_all_io_entry(pool, bio);
1975                         remap_and_issue(tc, bio, lookup_result.block);
1976                         inc_remap_and_issue_cell(tc, cell, lookup_result.block);
1977                 }
1978                 break;
1979
1980         case -ENODATA:
1981                 if (bio_data_dir(bio) == READ && tc->origin_dev) {
1982                         inc_all_io_entry(pool, bio);
1983                         cell_defer_no_holder(tc, cell);
1984
1985                         if (bio_end_sector(bio) <= tc->origin_size)
1986                                 remap_to_origin_and_issue(tc, bio);
1987
1988                         else if (bio->bi_iter.bi_sector < tc->origin_size) {
1989                                 zero_fill_bio(bio);
1990                                 bio->bi_iter.bi_size = (tc->origin_size - bio->bi_iter.bi_sector) << SECTOR_SHIFT;
1991                                 remap_to_origin_and_issue(tc, bio);
1992
1993                         } else {
1994                                 zero_fill_bio(bio);
1995                                 bio_endio(bio);
1996                         }
1997                 } else
1998                         provision_block(tc, bio, block, cell);
1999                 break;
2000
2001         default:
2002                 DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
2003                             __func__, r);
2004                 cell_defer_no_holder(tc, cell);
2005                 bio_io_error(bio);
2006                 break;
2007         }
2008 }
2009
2010 static void process_bio(struct thin_c *tc, struct bio *bio)
2011 {
2012         struct pool *pool = tc->pool;
2013         dm_block_t block = get_bio_block(tc, bio);
2014         struct dm_bio_prison_cell *cell;
2015         struct dm_cell_key key;
2016
2017         /*
2018          * If cell is already occupied, then the block is already
2019          * being provisioned so we have nothing further to do here.
2020          */
2021         build_virtual_key(tc->td, block, &key);
2022         if (bio_detain(pool, &key, bio, &cell))
2023                 return;
2024
2025         process_cell(tc, cell);
2026 }
2027
2028 static void __process_bio_read_only(struct thin_c *tc, struct bio *bio,
2029                                     struct dm_bio_prison_cell *cell)
2030 {
2031         int r;
2032         int rw = bio_data_dir(bio);
2033         dm_block_t block = get_bio_block(tc, bio);
2034         struct dm_thin_lookup_result lookup_result;
2035
2036         r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
2037         switch (r) {
2038         case 0:
2039                 if (lookup_result.shared && (rw == WRITE) && bio->bi_iter.bi_size) {
2040                         handle_unserviceable_bio(tc->pool, bio);
2041                         if (cell)
2042                                 cell_defer_no_holder(tc, cell);
2043                 } else {
2044                         inc_all_io_entry(tc->pool, bio);
2045                         remap_and_issue(tc, bio, lookup_result.block);
2046                         if (cell)
2047                                 inc_remap_and_issue_cell(tc, cell, lookup_result.block);
2048                 }
2049                 break;
2050
2051         case -ENODATA:
2052                 if (cell)
2053                         cell_defer_no_holder(tc, cell);
2054                 if (rw != READ) {
2055                         handle_unserviceable_bio(tc->pool, bio);
2056                         break;
2057                 }
2058
2059                 if (tc->origin_dev) {
2060                         inc_all_io_entry(tc->pool, bio);
2061                         remap_to_origin_and_issue(tc, bio);
2062                         break;
2063                 }
2064
2065                 zero_fill_bio(bio);
2066                 bio_endio(bio);
2067                 break;
2068
2069         default:
2070                 DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
2071                             __func__, r);
2072                 if (cell)
2073                         cell_defer_no_holder(tc, cell);
2074                 bio_io_error(bio);
2075                 break;
2076         }
2077 }
2078
2079 static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
2080 {
2081         __process_bio_read_only(tc, bio, NULL);
2082 }
2083
2084 static void process_cell_read_only(struct thin_c *tc, struct dm_bio_prison_cell *cell)
2085 {
2086         __process_bio_read_only(tc, cell->holder, cell);
2087 }
2088
2089 static void process_bio_success(struct thin_c *tc, struct bio *bio)
2090 {
2091         bio_endio(bio);
2092 }
2093
2094 static void process_bio_fail(struct thin_c *tc, struct bio *bio)
2095 {
2096         bio_io_error(bio);
2097 }
2098
2099 static void process_cell_success(struct thin_c *tc, struct dm_bio_prison_cell *cell)
2100 {
2101         cell_success(tc->pool, cell);
2102 }
2103
2104 static void process_cell_fail(struct thin_c *tc, struct dm_bio_prison_cell *cell)
2105 {
2106         cell_error(tc->pool, cell);
2107 }
2108
2109 /*
2110  * FIXME: should we also commit due to size of transaction, measured in
2111  * metadata blocks?
2112  */
2113 static int need_commit_due_to_time(struct pool *pool)
2114 {
2115         return !time_in_range(jiffies, pool->last_commit_jiffies,
2116                               pool->last_commit_jiffies + COMMIT_PERIOD);
2117 }
2118
2119 #define thin_pbd(node) rb_entry((node), struct dm_thin_endio_hook, rb_node)
2120 #define thin_bio(pbd) dm_bio_from_per_bio_data((pbd), sizeof(struct dm_thin_endio_hook))
2121
2122 static void __thin_bio_rb_add(struct thin_c *tc, struct bio *bio)
2123 {
2124         struct rb_node **rbp, *parent;
2125         struct dm_thin_endio_hook *pbd;
2126         sector_t bi_sector = bio->bi_iter.bi_sector;
2127
2128         rbp = &tc->sort_bio_list.rb_node;
2129         parent = NULL;
2130         while (*rbp) {
2131                 parent = *rbp;
2132                 pbd = thin_pbd(parent);
2133
2134                 if (bi_sector < thin_bio(pbd)->bi_iter.bi_sector)
2135                         rbp = &(*rbp)->rb_left;
2136                 else
2137                         rbp = &(*rbp)->rb_right;
2138         }
2139
2140         pbd = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
2141         rb_link_node(&pbd->rb_node, parent, rbp);
2142         rb_insert_color(&pbd->rb_node, &tc->sort_bio_list);
2143 }
2144
2145 static void __extract_sorted_bios(struct thin_c *tc)
2146 {
2147         struct rb_node *node;
2148         struct dm_thin_endio_hook *pbd;
2149         struct bio *bio;
2150
2151         for (node = rb_first(&tc->sort_bio_list); node; node = rb_next(node)) {
2152                 pbd = thin_pbd(node);
2153                 bio = thin_bio(pbd);
2154
2155                 bio_list_add(&tc->deferred_bio_list, bio);
2156                 rb_erase(&pbd->rb_node, &tc->sort_bio_list);
2157         }
2158
2159         WARN_ON(!RB_EMPTY_ROOT(&tc->sort_bio_list));
2160 }
2161
2162 static void __sort_thin_deferred_bios(struct thin_c *tc)
2163 {
2164         struct bio *bio;
2165         struct bio_list bios;
2166
2167         bio_list_init(&bios);
2168         bio_list_merge(&bios, &tc->deferred_bio_list);
2169         bio_list_init(&tc->deferred_bio_list);
2170
2171         /* Sort deferred_bio_list using rb-tree */
2172         while ((bio = bio_list_pop(&bios)))
2173                 __thin_bio_rb_add(tc, bio);
2174
2175         /*
2176          * Transfer the sorted bios in sort_bio_list back to
2177          * deferred_bio_list to allow lockless submission of
2178          * all bios.
2179          */
2180         __extract_sorted_bios(tc);
2181 }
2182
2183 static void process_thin_deferred_bios(struct thin_c *tc)
2184 {
2185         struct pool *pool = tc->pool;
2186         struct bio *bio;
2187         struct bio_list bios;
2188         struct blk_plug plug;
2189         unsigned int count = 0;
2190
2191         if (tc->requeue_mode) {
2192                 error_thin_bio_list(tc, &tc->deferred_bio_list,
2193                                 BLK_STS_DM_REQUEUE);
2194                 return;
2195         }
2196
2197         bio_list_init(&bios);
2198
2199         spin_lock_irq(&tc->lock);
2200
2201         if (bio_list_empty(&tc->deferred_bio_list)) {
2202                 spin_unlock_irq(&tc->lock);
2203                 return;
2204         }
2205
2206         __sort_thin_deferred_bios(tc);
2207
2208         bio_list_merge(&bios, &tc->deferred_bio_list);
2209         bio_list_init(&tc->deferred_bio_list);
2210
2211         spin_unlock_irq(&tc->lock);
2212
2213         blk_start_plug(&plug);
2214         while ((bio = bio_list_pop(&bios))) {
2215                 /*
2216                  * If we've got no free new_mapping structs, and processing
2217                  * this bio might require one, we pause until there are some
2218                  * prepared mappings to process.
2219                  */
2220                 if (ensure_next_mapping(pool)) {
2221                         spin_lock_irq(&tc->lock);
2222                         bio_list_add(&tc->deferred_bio_list, bio);
2223                         bio_list_merge(&tc->deferred_bio_list, &bios);
2224                         spin_unlock_irq(&tc->lock);
2225                         break;
2226                 }
2227
2228                 if (bio_op(bio) == REQ_OP_DISCARD)
2229                         pool->process_discard(tc, bio);
2230                 else
2231                         pool->process_bio(tc, bio);
2232
2233                 if ((count++ & 127) == 0) {
2234                         throttle_work_update(&pool->throttle);
2235                         dm_pool_issue_prefetches(pool->pmd);
2236                 }
2237                 cond_resched();
2238         }
2239         blk_finish_plug(&plug);
2240 }
2241
2242 static int cmp_cells(const void *lhs, const void *rhs)
2243 {
2244         struct dm_bio_prison_cell *lhs_cell = *((struct dm_bio_prison_cell **) lhs);
2245         struct dm_bio_prison_cell *rhs_cell = *((struct dm_bio_prison_cell **) rhs);
2246
2247         BUG_ON(!lhs_cell->holder);
2248         BUG_ON(!rhs_cell->holder);
2249
2250         if (lhs_cell->holder->bi_iter.bi_sector < rhs_cell->holder->bi_iter.bi_sector)
2251                 return -1;
2252
2253         if (lhs_cell->holder->bi_iter.bi_sector > rhs_cell->holder->bi_iter.bi_sector)
2254                 return 1;
2255
2256         return 0;
2257 }
2258
2259 static unsigned int sort_cells(struct pool *pool, struct list_head *cells)
2260 {
2261         unsigned int count = 0;
2262         struct dm_bio_prison_cell *cell, *tmp;
2263
2264         list_for_each_entry_safe(cell, tmp, cells, user_list) {
2265                 if (count >= CELL_SORT_ARRAY_SIZE)
2266                         break;
2267
2268                 pool->cell_sort_array[count++] = cell;
2269                 list_del(&cell->user_list);
2270         }
2271
2272         sort(pool->cell_sort_array, count, sizeof(cell), cmp_cells, NULL);
2273
2274         return count;
2275 }
2276
2277 static void process_thin_deferred_cells(struct thin_c *tc)
2278 {
2279         struct pool *pool = tc->pool;
2280         struct list_head cells;
2281         struct dm_bio_prison_cell *cell;
2282         unsigned int i, j, count;
2283
2284         INIT_LIST_HEAD(&cells);
2285
2286         spin_lock_irq(&tc->lock);
2287         list_splice_init(&tc->deferred_cells, &cells);
2288         spin_unlock_irq(&tc->lock);
2289
2290         if (list_empty(&cells))
2291                 return;
2292
2293         do {
2294                 count = sort_cells(tc->pool, &cells);
2295
2296                 for (i = 0; i < count; i++) {
2297                         cell = pool->cell_sort_array[i];
2298                         BUG_ON(!cell->holder);
2299
2300                         /*
2301                          * If we've got no free new_mapping structs, and processing
2302                          * this bio might require one, we pause until there are some
2303                          * prepared mappings to process.
2304                          */
2305                         if (ensure_next_mapping(pool)) {
2306                                 for (j = i; j < count; j++)
2307                                         list_add(&pool->cell_sort_array[j]->user_list, &cells);
2308
2309                                 spin_lock_irq(&tc->lock);
2310                                 list_splice(&cells, &tc->deferred_cells);
2311                                 spin_unlock_irq(&tc->lock);
2312                                 return;
2313                         }
2314
2315                         if (bio_op(cell->holder) == REQ_OP_DISCARD)
2316                                 pool->process_discard_cell(tc, cell);
2317                         else
2318                                 pool->process_cell(tc, cell);
2319                 }
2320                 cond_resched();
2321         } while (!list_empty(&cells));
2322 }
2323
2324 static void thin_get(struct thin_c *tc);
2325 static void thin_put(struct thin_c *tc);
2326
2327 /*
2328  * We can't hold rcu_read_lock() around code that can block.  So we
2329  * find a thin with the rcu lock held; bump a refcount; then drop
2330  * the lock.
2331  */
2332 static struct thin_c *get_first_thin(struct pool *pool)
2333 {
2334         struct thin_c *tc = NULL;
2335
2336         rcu_read_lock();
2337         if (!list_empty(&pool->active_thins)) {
2338                 tc = list_entry_rcu(pool->active_thins.next, struct thin_c, list);
2339                 thin_get(tc);
2340         }
2341         rcu_read_unlock();
2342
2343         return tc;
2344 }
2345
2346 static struct thin_c *get_next_thin(struct pool *pool, struct thin_c *tc)
2347 {
2348         struct thin_c *old_tc = tc;
2349
2350         rcu_read_lock();
2351         list_for_each_entry_continue_rcu(tc, &pool->active_thins, list) {
2352                 thin_get(tc);
2353                 thin_put(old_tc);
2354                 rcu_read_unlock();
2355                 return tc;
2356         }
2357         thin_put(old_tc);
2358         rcu_read_unlock();
2359
2360         return NULL;
2361 }
2362
2363 static void process_deferred_bios(struct pool *pool)
2364 {
2365         struct bio *bio;
2366         struct bio_list bios, bio_completions;
2367         struct thin_c *tc;
2368
2369         tc = get_first_thin(pool);
2370         while (tc) {
2371                 process_thin_deferred_cells(tc);
2372                 process_thin_deferred_bios(tc);
2373                 tc = get_next_thin(pool, tc);
2374         }
2375
2376         /*
2377          * If there are any deferred flush bios, we must commit the metadata
2378          * before issuing them or signaling their completion.
2379          */
2380         bio_list_init(&bios);
2381         bio_list_init(&bio_completions);
2382
2383         spin_lock_irq(&pool->lock);
2384         bio_list_merge(&bios, &pool->deferred_flush_bios);
2385         bio_list_init(&pool->deferred_flush_bios);
2386
2387         bio_list_merge(&bio_completions, &pool->deferred_flush_completions);
2388         bio_list_init(&pool->deferred_flush_completions);
2389         spin_unlock_irq(&pool->lock);
2390
2391         if (bio_list_empty(&bios) && bio_list_empty(&bio_completions) &&
2392             !(dm_pool_changed_this_transaction(pool->pmd) && need_commit_due_to_time(pool)))
2393                 return;
2394
2395         if (commit(pool)) {
2396                 bio_list_merge(&bios, &bio_completions);
2397
2398                 while ((bio = bio_list_pop(&bios)))
2399                         bio_io_error(bio);
2400                 return;
2401         }
2402         pool->last_commit_jiffies = jiffies;
2403
2404         while ((bio = bio_list_pop(&bio_completions)))
2405                 bio_endio(bio);
2406
2407         while ((bio = bio_list_pop(&bios))) {
2408                 /*
2409                  * The data device was flushed as part of metadata commit,
2410                  * so complete redundant flushes immediately.
2411                  */
2412                 if (bio->bi_opf & REQ_PREFLUSH)
2413                         bio_endio(bio);
2414                 else
2415                         dm_submit_bio_remap(bio, NULL);
2416         }
2417 }
2418
2419 static void do_worker(struct work_struct *ws)
2420 {
2421         struct pool *pool = container_of(ws, struct pool, worker);
2422
2423         throttle_work_start(&pool->throttle);
2424         dm_pool_issue_prefetches(pool->pmd);
2425         throttle_work_update(&pool->throttle);
2426         process_prepared(pool, &pool->prepared_mappings, &pool->process_prepared_mapping);
2427         throttle_work_update(&pool->throttle);
2428         process_prepared(pool, &pool->prepared_discards, &pool->process_prepared_discard);
2429         throttle_work_update(&pool->throttle);
2430         process_prepared(pool, &pool->prepared_discards_pt2, &pool->process_prepared_discard_pt2);
2431         throttle_work_update(&pool->throttle);
2432         process_deferred_bios(pool);
2433         throttle_work_complete(&pool->throttle);
2434 }
2435
2436 /*
2437  * We want to commit periodically so that not too much
2438  * unwritten data builds up.
2439  */
2440 static void do_waker(struct work_struct *ws)
2441 {
2442         struct pool *pool = container_of(to_delayed_work(ws), struct pool, waker);
2443
2444         wake_worker(pool);
2445         queue_delayed_work(pool->wq, &pool->waker, COMMIT_PERIOD);
2446 }
2447
2448 /*
2449  * We're holding onto IO to allow userland time to react.  After the
2450  * timeout either the pool will have been resized (and thus back in
2451  * PM_WRITE mode), or we degrade to PM_OUT_OF_DATA_SPACE w/ error_if_no_space.
2452  */
2453 static void do_no_space_timeout(struct work_struct *ws)
2454 {
2455         struct pool *pool = container_of(to_delayed_work(ws), struct pool,
2456                                          no_space_timeout);
2457
2458         if (get_pool_mode(pool) == PM_OUT_OF_DATA_SPACE && !pool->pf.error_if_no_space) {
2459                 pool->pf.error_if_no_space = true;
2460                 notify_of_pool_mode_change(pool);
2461                 error_retry_list_with_code(pool, BLK_STS_NOSPC);
2462         }
2463 }
2464
2465 /*----------------------------------------------------------------*/
2466
2467 struct pool_work {
2468         struct work_struct worker;
2469         struct completion complete;
2470 };
2471
2472 static struct pool_work *to_pool_work(struct work_struct *ws)
2473 {
2474         return container_of(ws, struct pool_work, worker);
2475 }
2476
2477 static void pool_work_complete(struct pool_work *pw)
2478 {
2479         complete(&pw->complete);
2480 }
2481
2482 static void pool_work_wait(struct pool_work *pw, struct pool *pool,
2483                            void (*fn)(struct work_struct *))
2484 {
2485         INIT_WORK_ONSTACK(&pw->worker, fn);
2486         init_completion(&pw->complete);
2487         queue_work(pool->wq, &pw->worker);
2488         wait_for_completion(&pw->complete);
2489 }
2490
2491 /*----------------------------------------------------------------*/
2492
2493 struct noflush_work {
2494         struct pool_work pw;
2495         struct thin_c *tc;
2496 };
2497
2498 static struct noflush_work *to_noflush(struct work_struct *ws)
2499 {
2500         return container_of(to_pool_work(ws), struct noflush_work, pw);
2501 }
2502
2503 static void do_noflush_start(struct work_struct *ws)
2504 {
2505         struct noflush_work *w = to_noflush(ws);
2506
2507         w->tc->requeue_mode = true;
2508         requeue_io(w->tc);
2509         pool_work_complete(&w->pw);
2510 }
2511
2512 static void do_noflush_stop(struct work_struct *ws)
2513 {
2514         struct noflush_work *w = to_noflush(ws);
2515
2516         w->tc->requeue_mode = false;
2517         pool_work_complete(&w->pw);
2518 }
2519
2520 static void noflush_work(struct thin_c *tc, void (*fn)(struct work_struct *))
2521 {
2522         struct noflush_work w;
2523
2524         w.tc = tc;
2525         pool_work_wait(&w.pw, tc->pool, fn);
2526 }
2527
2528 /*----------------------------------------------------------------*/
2529
2530 static void set_discard_callbacks(struct pool *pool)
2531 {
2532         struct pool_c *pt = pool->ti->private;
2533
2534         if (pt->adjusted_pf.discard_passdown) {
2535                 pool->process_discard_cell = process_discard_cell_passdown;
2536                 pool->process_prepared_discard = process_prepared_discard_passdown_pt1;
2537                 pool->process_prepared_discard_pt2 = process_prepared_discard_passdown_pt2;
2538         } else {
2539                 pool->process_discard_cell = process_discard_cell_no_passdown;
2540                 pool->process_prepared_discard = process_prepared_discard_no_passdown;
2541         }
2542 }
2543
2544 static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
2545 {
2546         struct pool_c *pt = pool->ti->private;
2547         bool needs_check = dm_pool_metadata_needs_check(pool->pmd);
2548         enum pool_mode old_mode = get_pool_mode(pool);
2549         unsigned long no_space_timeout = READ_ONCE(no_space_timeout_secs) * HZ;
2550
2551         /*
2552          * Never allow the pool to transition to PM_WRITE mode if user
2553          * intervention is required to verify metadata and data consistency.
2554          */
2555         if (new_mode == PM_WRITE && needs_check) {
2556                 DMERR("%s: unable to switch pool to write mode until repaired.",
2557                       dm_device_name(pool->pool_md));
2558                 if (old_mode != new_mode)
2559                         new_mode = old_mode;
2560                 else
2561                         new_mode = PM_READ_ONLY;
2562         }
2563         /*
2564          * If we were in PM_FAIL mode, rollback of metadata failed.  We're
2565          * not going to recover without a thin_repair.  So we never let the
2566          * pool move out of the old mode.
2567          */
2568         if (old_mode == PM_FAIL)
2569                 new_mode = old_mode;
2570
2571         switch (new_mode) {
2572         case PM_FAIL:
2573                 dm_pool_metadata_read_only(pool->pmd);
2574                 pool->process_bio = process_bio_fail;
2575                 pool->process_discard = process_bio_fail;
2576                 pool->process_cell = process_cell_fail;
2577                 pool->process_discard_cell = process_cell_fail;
2578                 pool->process_prepared_mapping = process_prepared_mapping_fail;
2579                 pool->process_prepared_discard = process_prepared_discard_fail;
2580
2581                 error_retry_list(pool);
2582                 break;
2583
2584         case PM_OUT_OF_METADATA_SPACE:
2585         case PM_READ_ONLY:
2586                 dm_pool_metadata_read_only(pool->pmd);
2587                 pool->process_bio = process_bio_read_only;
2588                 pool->process_discard = process_bio_success;
2589                 pool->process_cell = process_cell_read_only;
2590                 pool->process_discard_cell = process_cell_success;
2591                 pool->process_prepared_mapping = process_prepared_mapping_fail;
2592                 pool->process_prepared_discard = process_prepared_discard_success;
2593
2594                 error_retry_list(pool);
2595                 break;
2596
2597         case PM_OUT_OF_DATA_SPACE:
2598                 /*
2599                  * Ideally we'd never hit this state; the low water mark
2600                  * would trigger userland to extend the pool before we
2601                  * completely run out of data space.  However, many small
2602                  * IOs to unprovisioned space can consume data space at an
2603                  * alarming rate.  Adjust your low water mark if you're
2604                  * frequently seeing this mode.
2605                  */
2606                 pool->out_of_data_space = true;
2607                 pool->process_bio = process_bio_read_only;
2608                 pool->process_discard = process_discard_bio;
2609                 pool->process_cell = process_cell_read_only;
2610                 pool->process_prepared_mapping = process_prepared_mapping;
2611                 set_discard_callbacks(pool);
2612
2613                 if (!pool->pf.error_if_no_space && no_space_timeout)
2614                         queue_delayed_work(pool->wq, &pool->no_space_timeout, no_space_timeout);
2615                 break;
2616
2617         case PM_WRITE:
2618                 if (old_mode == PM_OUT_OF_DATA_SPACE)
2619                         cancel_delayed_work_sync(&pool->no_space_timeout);
2620                 pool->out_of_data_space = false;
2621                 pool->pf.error_if_no_space = pt->requested_pf.error_if_no_space;
2622                 dm_pool_metadata_read_write(pool->pmd);
2623                 pool->process_bio = process_bio;
2624                 pool->process_discard = process_discard_bio;
2625                 pool->process_cell = process_cell;
2626                 pool->process_prepared_mapping = process_prepared_mapping;
2627                 set_discard_callbacks(pool);
2628                 break;
2629         }
2630
2631         pool->pf.mode = new_mode;
2632         /*
2633          * The pool mode may have changed, sync it so bind_control_target()
2634          * doesn't cause an unexpected mode transition on resume.
2635          */
2636         pt->adjusted_pf.mode = new_mode;
2637
2638         if (old_mode != new_mode)
2639                 notify_of_pool_mode_change(pool);
2640 }
2641
2642 static void abort_transaction(struct pool *pool)
2643 {
2644         const char *dev_name = dm_device_name(pool->pool_md);
2645
2646         DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
2647         if (dm_pool_abort_metadata(pool->pmd)) {
2648                 DMERR("%s: failed to abort metadata transaction", dev_name);
2649                 set_pool_mode(pool, PM_FAIL);
2650         }
2651
2652         if (dm_pool_metadata_set_needs_check(pool->pmd)) {
2653                 DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
2654                 set_pool_mode(pool, PM_FAIL);
2655         }
2656 }
2657
2658 static void metadata_operation_failed(struct pool *pool, const char *op, int r)
2659 {
2660         DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
2661                     dm_device_name(pool->pool_md), op, r);
2662
2663         abort_transaction(pool);
2664         set_pool_mode(pool, PM_READ_ONLY);
2665 }
2666
2667 /*----------------------------------------------------------------*/
2668
2669 /*
2670  * Mapping functions.
2671  */
2672
2673 /*
2674  * Called only while mapping a thin bio to hand it over to the workqueue.
2675  */
2676 static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
2677 {
2678         struct pool *pool = tc->pool;
2679
2680         spin_lock_irq(&tc->lock);
2681         bio_list_add(&tc->deferred_bio_list, bio);
2682         spin_unlock_irq(&tc->lock);
2683
2684         wake_worker(pool);
2685 }
2686
2687 static void thin_defer_bio_with_throttle(struct thin_c *tc, struct bio *bio)
2688 {
2689         struct pool *pool = tc->pool;
2690
2691         throttle_lock(&pool->throttle);
2692         thin_defer_bio(tc, bio);
2693         throttle_unlock(&pool->throttle);
2694 }
2695
2696 static void thin_defer_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
2697 {
2698         struct pool *pool = tc->pool;
2699
2700         throttle_lock(&pool->throttle);
2701         spin_lock_irq(&tc->lock);
2702         list_add_tail(&cell->user_list, &tc->deferred_cells);
2703         spin_unlock_irq(&tc->lock);
2704         throttle_unlock(&pool->throttle);
2705
2706         wake_worker(pool);
2707 }
2708
2709 static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
2710 {
2711         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
2712
2713         h->tc = tc;
2714         h->shared_read_entry = NULL;
2715         h->all_io_entry = NULL;
2716         h->overwrite_mapping = NULL;
2717         h->cell = NULL;
2718 }
2719
2720 /*
2721  * Non-blocking function called from the thin target's map function.
2722  */
2723 static int thin_bio_map(struct dm_target *ti, struct bio *bio)
2724 {
2725         int r;
2726         struct thin_c *tc = ti->private;
2727         dm_block_t block = get_bio_block(tc, bio);
2728         struct dm_thin_device *td = tc->td;
2729         struct dm_thin_lookup_result result;
2730         struct dm_bio_prison_cell *virt_cell, *data_cell;
2731         struct dm_cell_key key;
2732
2733         thin_hook_bio(tc, bio);
2734
2735         if (tc->requeue_mode) {
2736                 bio->bi_status = BLK_STS_DM_REQUEUE;
2737                 bio_endio(bio);
2738                 return DM_MAPIO_SUBMITTED;
2739         }
2740
2741         if (get_pool_mode(tc->pool) == PM_FAIL) {
2742                 bio_io_error(bio);
2743                 return DM_MAPIO_SUBMITTED;
2744         }
2745
2746         if (op_is_flush(bio->bi_opf) || bio_op(bio) == REQ_OP_DISCARD) {
2747                 thin_defer_bio_with_throttle(tc, bio);
2748                 return DM_MAPIO_SUBMITTED;
2749         }
2750
2751         /*
2752          * We must hold the virtual cell before doing the lookup, otherwise
2753          * there's a race with discard.
2754          */
2755         build_virtual_key(tc->td, block, &key);
2756         if (bio_detain(tc->pool, &key, bio, &virt_cell))
2757                 return DM_MAPIO_SUBMITTED;
2758
2759         r = dm_thin_find_block(td, block, 0, &result);
2760
2761         /*
2762          * Note that we defer readahead too.
2763          */
2764         switch (r) {
2765         case 0:
2766                 if (unlikely(result.shared)) {
2767                         /*
2768                          * We have a race condition here between the
2769                          * result.shared value returned by the lookup and
2770                          * snapshot creation, which may cause new
2771                          * sharing.
2772                          *
2773                          * To avoid this always quiesce the origin before
2774                          * taking the snap.  You want to do this anyway to
2775                          * ensure a consistent application view
2776                          * (i.e. lockfs).
2777                          *
2778                          * More distant ancestors are irrelevant. The
2779                          * shared flag will be set in their case.
2780                          */
2781                         thin_defer_cell(tc, virt_cell);
2782                         return DM_MAPIO_SUBMITTED;
2783                 }
2784
2785                 build_data_key(tc->td, result.block, &key);
2786                 if (bio_detain(tc->pool, &key, bio, &data_cell)) {
2787                         cell_defer_no_holder(tc, virt_cell);
2788                         return DM_MAPIO_SUBMITTED;
2789                 }
2790
2791                 inc_all_io_entry(tc->pool, bio);
2792                 cell_defer_no_holder(tc, data_cell);
2793                 cell_defer_no_holder(tc, virt_cell);
2794
2795                 remap(tc, bio, result.block);
2796                 return DM_MAPIO_REMAPPED;
2797
2798         case -ENODATA:
2799         case -EWOULDBLOCK:
2800                 thin_defer_cell(tc, virt_cell);
2801                 return DM_MAPIO_SUBMITTED;
2802
2803         default:
2804                 /*
2805                  * Must always call bio_io_error on failure.
2806                  * dm_thin_find_block can fail with -EINVAL if the
2807                  * pool is switched to fail-io mode.
2808                  */
2809                 bio_io_error(bio);
2810                 cell_defer_no_holder(tc, virt_cell);
2811                 return DM_MAPIO_SUBMITTED;
2812         }
2813 }
2814
2815 static void requeue_bios(struct pool *pool)
2816 {
2817         struct thin_c *tc;
2818
2819         rcu_read_lock();
2820         list_for_each_entry_rcu(tc, &pool->active_thins, list) {
2821                 spin_lock_irq(&tc->lock);
2822                 bio_list_merge(&tc->deferred_bio_list, &tc->retry_on_resume_list);
2823                 bio_list_init(&tc->retry_on_resume_list);
2824                 spin_unlock_irq(&tc->lock);
2825         }
2826         rcu_read_unlock();
2827 }
2828
2829 /*
2830  *--------------------------------------------------------------
2831  * Binding of control targets to a pool object
2832  *--------------------------------------------------------------
2833  */
2834 static bool is_factor(sector_t block_size, uint32_t n)
2835 {
2836         return !sector_div(block_size, n);
2837 }
2838
2839 /*
2840  * If discard_passdown was enabled verify that the data device
2841  * supports discards.  Disable discard_passdown if not.
2842  */
2843 static void disable_discard_passdown_if_not_supported(struct pool_c *pt)
2844 {
2845         struct pool *pool = pt->pool;
2846         struct block_device *data_bdev = pt->data_dev->bdev;
2847         struct queue_limits *data_limits = &bdev_get_queue(data_bdev)->limits;
2848         const char *reason = NULL;
2849
2850         if (!pt->adjusted_pf.discard_passdown)
2851                 return;
2852
2853         if (!bdev_max_discard_sectors(pt->data_dev->bdev))
2854                 reason = "discard unsupported";
2855
2856         else if (data_limits->max_discard_sectors < pool->sectors_per_block)
2857                 reason = "max discard sectors smaller than a block";
2858
2859         if (reason) {
2860                 DMWARN("Data device (%pg) %s: Disabling discard passdown.", data_bdev, reason);
2861                 pt->adjusted_pf.discard_passdown = false;
2862         }
2863 }
2864
2865 static int bind_control_target(struct pool *pool, struct dm_target *ti)
2866 {
2867         struct pool_c *pt = ti->private;
2868
2869         /*
2870          * We want to make sure that a pool in PM_FAIL mode is never upgraded.
2871          */
2872         enum pool_mode old_mode = get_pool_mode(pool);
2873         enum pool_mode new_mode = pt->adjusted_pf.mode;
2874
2875         /*
2876          * Don't change the pool's mode until set_pool_mode() below.
2877          * Otherwise the pool's process_* function pointers may
2878          * not match the desired pool mode.
2879          */
2880         pt->adjusted_pf.mode = old_mode;
2881
2882         pool->ti = ti;
2883         pool->pf = pt->adjusted_pf;
2884         pool->low_water_blocks = pt->low_water_blocks;
2885
2886         set_pool_mode(pool, new_mode);
2887
2888         return 0;
2889 }
2890
2891 static void unbind_control_target(struct pool *pool, struct dm_target *ti)
2892 {
2893         if (pool->ti == ti)
2894                 pool->ti = NULL;
2895 }
2896
2897 /*
2898  *--------------------------------------------------------------
2899  * Pool creation
2900  *--------------------------------------------------------------
2901  */
2902 /* Initialize pool features. */
2903 static void pool_features_init(struct pool_features *pf)
2904 {
2905         pf->mode = PM_WRITE;
2906         pf->zero_new_blocks = true;
2907         pf->discard_enabled = true;
2908         pf->discard_passdown = true;
2909         pf->error_if_no_space = false;
2910 }
2911
2912 static void __pool_destroy(struct pool *pool)
2913 {
2914         __pool_table_remove(pool);
2915
2916         vfree(pool->cell_sort_array);
2917         if (dm_pool_metadata_close(pool->pmd) < 0)
2918                 DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
2919
2920         dm_bio_prison_destroy(pool->prison);
2921         dm_kcopyd_client_destroy(pool->copier);
2922
2923         cancel_delayed_work_sync(&pool->waker);
2924         cancel_delayed_work_sync(&pool->no_space_timeout);
2925         if (pool->wq)
2926                 destroy_workqueue(pool->wq);
2927
2928         if (pool->next_mapping)
2929                 mempool_free(pool->next_mapping, &pool->mapping_pool);
2930         mempool_exit(&pool->mapping_pool);
2931         dm_deferred_set_destroy(pool->shared_read_ds);
2932         dm_deferred_set_destroy(pool->all_io_ds);
2933         kfree(pool);
2934 }
2935
2936 static struct kmem_cache *_new_mapping_cache;
2937
2938 static struct pool *pool_create(struct mapped_device *pool_md,
2939                                 struct block_device *metadata_dev,
2940                                 struct block_device *data_dev,
2941                                 unsigned long block_size,
2942                                 int read_only, char **error)
2943 {
2944         int r;
2945         void *err_p;
2946         struct pool *pool;
2947         struct dm_pool_metadata *pmd;
2948         bool format_device = read_only ? false : true;
2949
2950         pmd = dm_pool_metadata_open(metadata_dev, block_size, format_device);
2951         if (IS_ERR(pmd)) {
2952                 *error = "Error creating metadata object";
2953                 return (struct pool *)pmd;
2954         }
2955
2956         pool = kzalloc(sizeof(*pool), GFP_KERNEL);
2957         if (!pool) {
2958                 *error = "Error allocating memory for pool";
2959                 err_p = ERR_PTR(-ENOMEM);
2960                 goto bad_pool;
2961         }
2962
2963         pool->pmd = pmd;
2964         pool->sectors_per_block = block_size;
2965         if (block_size & (block_size - 1))
2966                 pool->sectors_per_block_shift = -1;
2967         else
2968                 pool->sectors_per_block_shift = __ffs(block_size);
2969         pool->low_water_blocks = 0;
2970         pool_features_init(&pool->pf);
2971         pool->prison = dm_bio_prison_create();
2972         if (!pool->prison) {
2973                 *error = "Error creating pool's bio prison";
2974                 err_p = ERR_PTR(-ENOMEM);
2975                 goto bad_prison;
2976         }
2977
2978         pool->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2979         if (IS_ERR(pool->copier)) {
2980                 r = PTR_ERR(pool->copier);
2981                 *error = "Error creating pool's kcopyd client";
2982                 err_p = ERR_PTR(r);
2983                 goto bad_kcopyd_client;
2984         }
2985
2986         /*
2987          * Create singlethreaded workqueue that will service all devices
2988          * that use this metadata.
2989          */
2990         pool->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
2991         if (!pool->wq) {
2992                 *error = "Error creating pool's workqueue";
2993                 err_p = ERR_PTR(-ENOMEM);
2994                 goto bad_wq;
2995         }
2996
2997         throttle_init(&pool->throttle);
2998         INIT_WORK(&pool->worker, do_worker);
2999         INIT_DELAYED_WORK(&pool->waker, do_waker);
3000         INIT_DELAYED_WORK(&pool->no_space_timeout, do_no_space_timeout);
3001         spin_lock_init(&pool->lock);
3002         bio_list_init(&pool->deferred_flush_bios);
3003         bio_list_init(&pool->deferred_flush_completions);
3004         INIT_LIST_HEAD(&pool->prepared_mappings);
3005         INIT_LIST_HEAD(&pool->prepared_discards);
3006         INIT_LIST_HEAD(&pool->prepared_discards_pt2);
3007         INIT_LIST_HEAD(&pool->active_thins);
3008         pool->low_water_triggered = false;
3009         pool->suspended = true;
3010         pool->out_of_data_space = false;
3011
3012         pool->shared_read_ds = dm_deferred_set_create();
3013         if (!pool->shared_read_ds) {
3014                 *error = "Error creating pool's shared read deferred set";
3015                 err_p = ERR_PTR(-ENOMEM);
3016                 goto bad_shared_read_ds;
3017         }
3018
3019         pool->all_io_ds = dm_deferred_set_create();
3020         if (!pool->all_io_ds) {
3021                 *error = "Error creating pool's all io deferred set";
3022                 err_p = ERR_PTR(-ENOMEM);
3023                 goto bad_all_io_ds;
3024         }
3025
3026         pool->next_mapping = NULL;
3027         r = mempool_init_slab_pool(&pool->mapping_pool, MAPPING_POOL_SIZE,
3028                                    _new_mapping_cache);
3029         if (r) {
3030                 *error = "Error creating pool's mapping mempool";
3031                 err_p = ERR_PTR(r);
3032                 goto bad_mapping_pool;
3033         }
3034
3035         pool->cell_sort_array =
3036                 vmalloc(array_size(CELL_SORT_ARRAY_SIZE,
3037                                    sizeof(*pool->cell_sort_array)));
3038         if (!pool->cell_sort_array) {
3039                 *error = "Error allocating cell sort array";
3040                 err_p = ERR_PTR(-ENOMEM);
3041                 goto bad_sort_array;
3042         }
3043
3044         pool->ref_count = 1;
3045         pool->last_commit_jiffies = jiffies;
3046         pool->pool_md = pool_md;
3047         pool->md_dev = metadata_dev;
3048         pool->data_dev = data_dev;
3049         __pool_table_insert(pool);
3050
3051         return pool;
3052
3053 bad_sort_array:
3054         mempool_exit(&pool->mapping_pool);
3055 bad_mapping_pool:
3056         dm_deferred_set_destroy(pool->all_io_ds);
3057 bad_all_io_ds:
3058         dm_deferred_set_destroy(pool->shared_read_ds);
3059 bad_shared_read_ds:
3060         destroy_workqueue(pool->wq);
3061 bad_wq:
3062         dm_kcopyd_client_destroy(pool->copier);
3063 bad_kcopyd_client:
3064         dm_bio_prison_destroy(pool->prison);
3065 bad_prison:
3066         kfree(pool);
3067 bad_pool:
3068         if (dm_pool_metadata_close(pmd))
3069                 DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
3070
3071         return err_p;
3072 }
3073
3074 static void __pool_inc(struct pool *pool)
3075 {
3076         BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
3077         pool->ref_count++;
3078 }
3079
3080 static void __pool_dec(struct pool *pool)
3081 {
3082         BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
3083         BUG_ON(!pool->ref_count);
3084         if (!--pool->ref_count)
3085                 __pool_destroy(pool);
3086 }
3087
3088 static struct pool *__pool_find(struct mapped_device *pool_md,
3089                                 struct block_device *metadata_dev,
3090                                 struct block_device *data_dev,
3091                                 unsigned long block_size, int read_only,
3092                                 char **error, int *created)
3093 {
3094         struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev);
3095
3096         if (pool) {
3097                 if (pool->pool_md != pool_md) {
3098                         *error = "metadata device already in use by a pool";
3099                         return ERR_PTR(-EBUSY);
3100                 }
3101                 if (pool->data_dev != data_dev) {
3102                         *error = "data device already in use by a pool";
3103                         return ERR_PTR(-EBUSY);
3104                 }
3105                 __pool_inc(pool);
3106
3107         } else {
3108                 pool = __pool_table_lookup(pool_md);
3109                 if (pool) {
3110                         if (pool->md_dev != metadata_dev || pool->data_dev != data_dev) {
3111                                 *error = "different pool cannot replace a pool";
3112                                 return ERR_PTR(-EINVAL);
3113                         }
3114                         __pool_inc(pool);
3115
3116                 } else {
3117                         pool = pool_create(pool_md, metadata_dev, data_dev, block_size, read_only, error);
3118                         *created = 1;
3119                 }
3120         }
3121
3122         return pool;
3123 }
3124
3125 /*
3126  *--------------------------------------------------------------
3127  * Pool target methods
3128  *--------------------------------------------------------------
3129  */
3130 static void pool_dtr(struct dm_target *ti)
3131 {
3132         struct pool_c *pt = ti->private;
3133
3134         mutex_lock(&dm_thin_pool_table.mutex);
3135
3136         unbind_control_target(pt->pool, ti);
3137         __pool_dec(pt->pool);
3138         dm_put_device(ti, pt->metadata_dev);
3139         dm_put_device(ti, pt->data_dev);
3140         kfree(pt);
3141
3142         mutex_unlock(&dm_thin_pool_table.mutex);
3143 }
3144
3145 static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
3146                                struct dm_target *ti)
3147 {
3148         int r;
3149         unsigned int argc;
3150         const char *arg_name;
3151
3152         static const struct dm_arg _args[] = {
3153                 {0, 4, "Invalid number of pool feature arguments"},
3154         };
3155
3156         /*
3157          * No feature arguments supplied.
3158          */
3159         if (!as->argc)
3160                 return 0;
3161
3162         r = dm_read_arg_group(_args, as, &argc, &ti->error);
3163         if (r)
3164                 return -EINVAL;
3165
3166         while (argc && !r) {
3167                 arg_name = dm_shift_arg(as);
3168                 argc--;
3169
3170                 if (!strcasecmp(arg_name, "skip_block_zeroing"))
3171                         pf->zero_new_blocks = false;
3172
3173                 else if (!strcasecmp(arg_name, "ignore_discard"))
3174                         pf->discard_enabled = false;
3175
3176                 else if (!strcasecmp(arg_name, "no_discard_passdown"))
3177                         pf->discard_passdown = false;
3178
3179                 else if (!strcasecmp(arg_name, "read_only"))
3180                         pf->mode = PM_READ_ONLY;
3181
3182                 else if (!strcasecmp(arg_name, "error_if_no_space"))
3183                         pf->error_if_no_space = true;
3184
3185                 else {
3186                         ti->error = "Unrecognised pool feature requested";
3187                         r = -EINVAL;
3188                         break;
3189                 }
3190         }
3191
3192         return r;
3193 }
3194
3195 static void metadata_low_callback(void *context)
3196 {
3197         struct pool *pool = context;
3198
3199         DMWARN("%s: reached low water mark for metadata device: sending event.",
3200                dm_device_name(pool->pool_md));
3201
3202         dm_table_event(pool->ti->table);
3203 }
3204
3205 /*
3206  * We need to flush the data device **before** committing the metadata.
3207  *
3208  * This ensures that the data blocks of any newly inserted mappings are
3209  * properly written to non-volatile storage and won't be lost in case of a
3210  * crash.
3211  *
3212  * Failure to do so can result in data corruption in the case of internal or
3213  * external snapshots and in the case of newly provisioned blocks, when block
3214  * zeroing is enabled.
3215  */
3216 static int metadata_pre_commit_callback(void *context)
3217 {
3218         struct pool *pool = context;
3219
3220         return blkdev_issue_flush(pool->data_dev);
3221 }
3222
3223 static sector_t get_dev_size(struct block_device *bdev)
3224 {
3225         return bdev_nr_sectors(bdev);
3226 }
3227
3228 static void warn_if_metadata_device_too_big(struct block_device *bdev)
3229 {
3230         sector_t metadata_dev_size = get_dev_size(bdev);
3231
3232         if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING)
3233                 DMWARN("Metadata device %pg is larger than %u sectors: excess space will not be used.",
3234                        bdev, THIN_METADATA_MAX_SECTORS);
3235 }
3236
3237 static sector_t get_metadata_dev_size(struct block_device *bdev)
3238 {
3239         sector_t metadata_dev_size = get_dev_size(bdev);
3240
3241         if (metadata_dev_size > THIN_METADATA_MAX_SECTORS)
3242                 metadata_dev_size = THIN_METADATA_MAX_SECTORS;
3243
3244         return metadata_dev_size;
3245 }
3246
3247 static dm_block_t get_metadata_dev_size_in_blocks(struct block_device *bdev)
3248 {
3249         sector_t metadata_dev_size = get_metadata_dev_size(bdev);
3250
3251         sector_div(metadata_dev_size, THIN_METADATA_BLOCK_SIZE);
3252
3253         return metadata_dev_size;
3254 }
3255
3256 /*
3257  * When a metadata threshold is crossed a dm event is triggered, and
3258  * userland should respond by growing the metadata device.  We could let
3259  * userland set the threshold, like we do with the data threshold, but I'm
3260  * not sure they know enough to do this well.
3261  */
3262 static dm_block_t calc_metadata_threshold(struct pool_c *pt)
3263 {
3264         /*
3265          * 4M is ample for all ops with the possible exception of thin
3266          * device deletion which is harmless if it fails (just retry the
3267          * delete after you've grown the device).
3268          */
3269         dm_block_t quarter = get_metadata_dev_size_in_blocks(pt->metadata_dev->bdev) / 4;
3270
3271         return min((dm_block_t)1024ULL /* 4M */, quarter);
3272 }
3273
3274 /*
3275  * thin-pool <metadata dev> <data dev>
3276  *           <data block size (sectors)>
3277  *           <low water mark (blocks)>
3278  *           [<#feature args> [<arg>]*]
3279  *
3280  * Optional feature arguments are:
3281  *           skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
3282  *           ignore_discard: disable discard
3283  *           no_discard_passdown: don't pass discards down to the data device
3284  *           read_only: Don't allow any changes to be made to the pool metadata.
3285  *           error_if_no_space: error IOs, instead of queueing, if no space.
3286  */
3287 static int pool_ctr(struct dm_target *ti, unsigned int argc, char **argv)
3288 {
3289         int r, pool_created = 0;
3290         struct pool_c *pt;
3291         struct pool *pool;
3292         struct pool_features pf;
3293         struct dm_arg_set as;
3294         struct dm_dev *data_dev;
3295         unsigned long block_size;
3296         dm_block_t low_water_blocks;
3297         struct dm_dev *metadata_dev;
3298         blk_mode_t metadata_mode;
3299
3300         /*
3301          * FIXME Remove validation from scope of lock.
3302          */
3303         mutex_lock(&dm_thin_pool_table.mutex);
3304
3305         if (argc < 4) {
3306                 ti->error = "Invalid argument count";
3307                 r = -EINVAL;
3308                 goto out_unlock;
3309         }
3310
3311         as.argc = argc;
3312         as.argv = argv;
3313
3314         /* make sure metadata and data are different devices */
3315         if (!strcmp(argv[0], argv[1])) {
3316                 ti->error = "Error setting metadata or data device";
3317                 r = -EINVAL;
3318                 goto out_unlock;
3319         }
3320
3321         /*
3322          * Set default pool features.
3323          */
3324         pool_features_init(&pf);
3325
3326         dm_consume_args(&as, 4);
3327         r = parse_pool_features(&as, &pf, ti);
3328         if (r)
3329                 goto out_unlock;
3330
3331         metadata_mode = BLK_OPEN_READ |
3332                 ((pf.mode == PM_READ_ONLY) ? 0 : BLK_OPEN_WRITE);
3333         r = dm_get_device(ti, argv[0], metadata_mode, &metadata_dev);
3334         if (r) {
3335                 ti->error = "Error opening metadata block device";
3336                 goto out_unlock;
3337         }
3338         warn_if_metadata_device_too_big(metadata_dev->bdev);
3339
3340         r = dm_get_device(ti, argv[1], BLK_OPEN_READ | BLK_OPEN_WRITE, &data_dev);
3341         if (r) {
3342                 ti->error = "Error getting data device";
3343                 goto out_metadata;
3344         }
3345
3346         if (kstrtoul(argv[2], 10, &block_size) || !block_size ||
3347             block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
3348             block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
3349             block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
3350                 ti->error = "Invalid block size";
3351                 r = -EINVAL;
3352                 goto out;
3353         }
3354
3355         if (kstrtoull(argv[3], 10, (unsigned long long *)&low_water_blocks)) {
3356                 ti->error = "Invalid low water mark";
3357                 r = -EINVAL;
3358                 goto out;
3359         }
3360
3361         pt = kzalloc(sizeof(*pt), GFP_KERNEL);
3362         if (!pt) {
3363                 r = -ENOMEM;
3364                 goto out;
3365         }
3366
3367         pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev, data_dev->bdev,
3368                            block_size, pf.mode == PM_READ_ONLY, &ti->error, &pool_created);
3369         if (IS_ERR(pool)) {
3370                 r = PTR_ERR(pool);
3371                 goto out_free_pt;
3372         }
3373
3374         /*
3375          * 'pool_created' reflects whether this is the first table load.
3376          * Top level discard support is not allowed to be changed after
3377          * initial load.  This would require a pool reload to trigger thin
3378          * device changes.
3379          */
3380         if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
3381                 ti->error = "Discard support cannot be disabled once enabled";
3382                 r = -EINVAL;
3383                 goto out_flags_changed;
3384         }
3385
3386         pt->pool = pool;
3387         pt->ti = ti;
3388         pt->metadata_dev = metadata_dev;
3389         pt->data_dev = data_dev;
3390         pt->low_water_blocks = low_water_blocks;
3391         pt->adjusted_pf = pt->requested_pf = pf;
3392         ti->num_flush_bios = 1;
3393         ti->limit_swap_bios = true;
3394
3395         /*
3396          * Only need to enable discards if the pool should pass
3397          * them down to the data device.  The thin device's discard
3398          * processing will cause mappings to be removed from the btree.
3399          */
3400         if (pf.discard_enabled && pf.discard_passdown) {
3401                 ti->num_discard_bios = 1;
3402                 /*
3403                  * Setting 'discards_supported' circumvents the normal
3404                  * stacking of discard limits (this keeps the pool and
3405                  * thin devices' discard limits consistent).
3406                  */
3407                 ti->discards_supported = true;
3408                 ti->max_discard_granularity = true;
3409         }
3410         ti->private = pt;
3411
3412         r = dm_pool_register_metadata_threshold(pt->pool->pmd,
3413                                                 calc_metadata_threshold(pt),
3414                                                 metadata_low_callback,
3415                                                 pool);
3416         if (r) {
3417                 ti->error = "Error registering metadata threshold";
3418                 goto out_flags_changed;
3419         }
3420
3421         dm_pool_register_pre_commit_callback(pool->pmd,
3422                                              metadata_pre_commit_callback, pool);
3423
3424         mutex_unlock(&dm_thin_pool_table.mutex);
3425
3426         return 0;
3427
3428 out_flags_changed:
3429         __pool_dec(pool);
3430 out_free_pt:
3431         kfree(pt);
3432 out:
3433         dm_put_device(ti, data_dev);
3434 out_metadata:
3435         dm_put_device(ti, metadata_dev);
3436 out_unlock:
3437         mutex_unlock(&dm_thin_pool_table.mutex);
3438
3439         return r;
3440 }
3441
3442 static int pool_map(struct dm_target *ti, struct bio *bio)
3443 {
3444         struct pool_c *pt = ti->private;
3445         struct pool *pool = pt->pool;
3446
3447         /*
3448          * As this is a singleton target, ti->begin is always zero.
3449          */
3450         spin_lock_irq(&pool->lock);
3451         bio_set_dev(bio, pt->data_dev->bdev);
3452         spin_unlock_irq(&pool->lock);
3453
3454         return DM_MAPIO_REMAPPED;
3455 }
3456
3457 static int maybe_resize_data_dev(struct dm_target *ti, bool *need_commit)
3458 {
3459         int r;
3460         struct pool_c *pt = ti->private;
3461         struct pool *pool = pt->pool;
3462         sector_t data_size = ti->len;
3463         dm_block_t sb_data_size;
3464
3465         *need_commit = false;
3466
3467         (void) sector_div(data_size, pool->sectors_per_block);
3468
3469         r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size);
3470         if (r) {
3471                 DMERR("%s: failed to retrieve data device size",
3472                       dm_device_name(pool->pool_md));
3473                 return r;
3474         }
3475
3476         if (data_size < sb_data_size) {
3477                 DMERR("%s: pool target (%llu blocks) too small: expected %llu",
3478                       dm_device_name(pool->pool_md),
3479                       (unsigned long long)data_size, sb_data_size);
3480                 return -EINVAL;
3481
3482         } else if (data_size > sb_data_size) {
3483                 if (dm_pool_metadata_needs_check(pool->pmd)) {
3484                         DMERR("%s: unable to grow the data device until repaired.",
3485                               dm_device_name(pool->pool_md));
3486                         return 0;
3487                 }
3488
3489                 if (sb_data_size)
3490                         DMINFO("%s: growing the data device from %llu to %llu blocks",
3491                                dm_device_name(pool->pool_md),
3492                                sb_data_size, (unsigned long long)data_size);
3493                 r = dm_pool_resize_data_dev(pool->pmd, data_size);
3494                 if (r) {
3495                         metadata_operation_failed(pool, "dm_pool_resize_data_dev", r);
3496                         return r;
3497                 }
3498
3499                 *need_commit = true;
3500         }
3501
3502         return 0;
3503 }
3504
3505 static int maybe_resize_metadata_dev(struct dm_target *ti, bool *need_commit)
3506 {
3507         int r;
3508         struct pool_c *pt = ti->private;
3509         struct pool *pool = pt->pool;
3510         dm_block_t metadata_dev_size, sb_metadata_dev_size;
3511
3512         *need_commit = false;
3513
3514         metadata_dev_size = get_metadata_dev_size_in_blocks(pool->md_dev);
3515
3516         r = dm_pool_get_metadata_dev_size(pool->pmd, &sb_metadata_dev_size);
3517         if (r) {
3518                 DMERR("%s: failed to retrieve metadata device size",
3519                       dm_device_name(pool->pool_md));
3520                 return r;
3521         }
3522
3523         if (metadata_dev_size < sb_metadata_dev_size) {
3524                 DMERR("%s: metadata device (%llu blocks) too small: expected %llu",
3525                       dm_device_name(pool->pool_md),
3526                       metadata_dev_size, sb_metadata_dev_size);
3527                 return -EINVAL;
3528
3529         } else if (metadata_dev_size > sb_metadata_dev_size) {
3530                 if (dm_pool_metadata_needs_check(pool->pmd)) {
3531                         DMERR("%s: unable to grow the metadata device until repaired.",
3532                               dm_device_name(pool->pool_md));
3533                         return 0;
3534                 }
3535
3536                 warn_if_metadata_device_too_big(pool->md_dev);
3537                 DMINFO("%s: growing the metadata device from %llu to %llu blocks",
3538                        dm_device_name(pool->pool_md),
3539                        sb_metadata_dev_size, metadata_dev_size);
3540
3541                 if (get_pool_mode(pool) == PM_OUT_OF_METADATA_SPACE)
3542                         set_pool_mode(pool, PM_WRITE);
3543
3544                 r = dm_pool_resize_metadata_dev(pool->pmd, metadata_dev_size);
3545                 if (r) {
3546                         metadata_operation_failed(pool, "dm_pool_resize_metadata_dev", r);
3547                         return r;
3548                 }
3549
3550                 *need_commit = true;
3551         }
3552
3553         return 0;
3554 }
3555
3556 /*
3557  * Retrieves the number of blocks of the data device from
3558  * the superblock and compares it to the actual device size,
3559  * thus resizing the data device in case it has grown.
3560  *
3561  * This both copes with opening preallocated data devices in the ctr
3562  * being followed by a resume
3563  * -and-
3564  * calling the resume method individually after userspace has
3565  * grown the data device in reaction to a table event.
3566  */
3567 static int pool_preresume(struct dm_target *ti)
3568 {
3569         int r;
3570         bool need_commit1, need_commit2;
3571         struct pool_c *pt = ti->private;
3572         struct pool *pool = pt->pool;
3573
3574         /*
3575          * Take control of the pool object.
3576          */
3577         r = bind_control_target(pool, ti);
3578         if (r)
3579                 goto out;
3580
3581         r = maybe_resize_data_dev(ti, &need_commit1);
3582         if (r)
3583                 goto out;
3584
3585         r = maybe_resize_metadata_dev(ti, &need_commit2);
3586         if (r)
3587                 goto out;
3588
3589         if (need_commit1 || need_commit2)
3590                 (void) commit(pool);
3591 out:
3592         /*
3593          * When a thin-pool is PM_FAIL, it cannot be rebuilt if
3594          * bio is in deferred list. Therefore need to return 0
3595          * to allow pool_resume() to flush IO.
3596          */
3597         if (r && get_pool_mode(pool) == PM_FAIL)
3598                 r = 0;
3599
3600         return r;
3601 }
3602
3603 static void pool_suspend_active_thins(struct pool *pool)
3604 {
3605         struct thin_c *tc;
3606
3607         /* Suspend all active thin devices */
3608         tc = get_first_thin(pool);
3609         while (tc) {
3610                 dm_internal_suspend_noflush(tc->thin_md);
3611                 tc = get_next_thin(pool, tc);
3612         }
3613 }
3614
3615 static void pool_resume_active_thins(struct pool *pool)
3616 {
3617         struct thin_c *tc;
3618
3619         /* Resume all active thin devices */
3620         tc = get_first_thin(pool);
3621         while (tc) {
3622                 dm_internal_resume(tc->thin_md);
3623                 tc = get_next_thin(pool, tc);
3624         }
3625 }
3626
3627 static void pool_resume(struct dm_target *ti)
3628 {
3629         struct pool_c *pt = ti->private;
3630         struct pool *pool = pt->pool;
3631
3632         /*
3633          * Must requeue active_thins' bios and then resume
3634          * active_thins _before_ clearing 'suspend' flag.
3635          */
3636         requeue_bios(pool);
3637         pool_resume_active_thins(pool);
3638
3639         spin_lock_irq(&pool->lock);
3640         pool->low_water_triggered = false;
3641         pool->suspended = false;
3642         spin_unlock_irq(&pool->lock);
3643
3644         do_waker(&pool->waker.work);
3645 }
3646
3647 static void pool_presuspend(struct dm_target *ti)
3648 {
3649         struct pool_c *pt = ti->private;
3650         struct pool *pool = pt->pool;
3651
3652         spin_lock_irq(&pool->lock);
3653         pool->suspended = true;
3654         spin_unlock_irq(&pool->lock);
3655
3656         pool_suspend_active_thins(pool);
3657 }
3658
3659 static void pool_presuspend_undo(struct dm_target *ti)
3660 {
3661         struct pool_c *pt = ti->private;
3662         struct pool *pool = pt->pool;
3663
3664         pool_resume_active_thins(pool);
3665
3666         spin_lock_irq(&pool->lock);
3667         pool->suspended = false;
3668         spin_unlock_irq(&pool->lock);
3669 }
3670
3671 static void pool_postsuspend(struct dm_target *ti)
3672 {
3673         struct pool_c *pt = ti->private;
3674         struct pool *pool = pt->pool;
3675
3676         cancel_delayed_work_sync(&pool->waker);
3677         cancel_delayed_work_sync(&pool->no_space_timeout);
3678         flush_workqueue(pool->wq);
3679         (void) commit(pool);
3680 }
3681
3682 static int check_arg_count(unsigned int argc, unsigned int args_required)
3683 {
3684         if (argc != args_required) {
3685                 DMWARN("Message received with %u arguments instead of %u.",
3686                        argc, args_required);
3687                 return -EINVAL;
3688         }
3689
3690         return 0;
3691 }
3692
3693 static int read_dev_id(char *arg, dm_thin_id *dev_id, int warning)
3694 {
3695         if (!kstrtoull(arg, 10, (unsigned long long *)dev_id) &&
3696             *dev_id <= MAX_DEV_ID)
3697                 return 0;
3698
3699         if (warning)
3700                 DMWARN("Message received with invalid device id: %s", arg);
3701
3702         return -EINVAL;
3703 }
3704
3705 static int process_create_thin_mesg(unsigned int argc, char **argv, struct pool *pool)
3706 {
3707         dm_thin_id dev_id;
3708         int r;
3709
3710         r = check_arg_count(argc, 2);
3711         if (r)
3712                 return r;
3713
3714         r = read_dev_id(argv[1], &dev_id, 1);
3715         if (r)
3716                 return r;
3717
3718         r = dm_pool_create_thin(pool->pmd, dev_id);
3719         if (r) {
3720                 DMWARN("Creation of new thinly-provisioned device with id %s failed.",
3721                        argv[1]);
3722                 return r;
3723         }
3724
3725         return 0;
3726 }
3727
3728 static int process_create_snap_mesg(unsigned int argc, char **argv, struct pool *pool)
3729 {
3730         dm_thin_id dev_id;
3731         dm_thin_id origin_dev_id;
3732         int r;
3733
3734         r = check_arg_count(argc, 3);
3735         if (r)
3736                 return r;
3737
3738         r = read_dev_id(argv[1], &dev_id, 1);
3739         if (r)
3740                 return r;
3741
3742         r = read_dev_id(argv[2], &origin_dev_id, 1);
3743         if (r)
3744                 return r;
3745
3746         r = dm_pool_create_snap(pool->pmd, dev_id, origin_dev_id);
3747         if (r) {
3748                 DMWARN("Creation of new snapshot %s of device %s failed.",
3749                        argv[1], argv[2]);
3750                 return r;
3751         }
3752
3753         return 0;
3754 }
3755
3756 static int process_delete_mesg(unsigned int argc, char **argv, struct pool *pool)
3757 {
3758         dm_thin_id dev_id;
3759         int r;
3760
3761         r = check_arg_count(argc, 2);
3762         if (r)
3763                 return r;
3764
3765         r = read_dev_id(argv[1], &dev_id, 1);
3766         if (r)
3767                 return r;
3768
3769         r = dm_pool_delete_thin_device(pool->pmd, dev_id);
3770         if (r)
3771                 DMWARN("Deletion of thin device %s failed.", argv[1]);
3772
3773         return r;
3774 }
3775
3776 static int process_set_transaction_id_mesg(unsigned int argc, char **argv, struct pool *pool)
3777 {
3778         dm_thin_id old_id, new_id;
3779         int r;
3780
3781         r = check_arg_count(argc, 3);
3782         if (r)
3783                 return r;
3784
3785         if (kstrtoull(argv[1], 10, (unsigned long long *)&old_id)) {
3786                 DMWARN("set_transaction_id message: Unrecognised id %s.", argv[1]);
3787                 return -EINVAL;
3788         }
3789
3790         if (kstrtoull(argv[2], 10, (unsigned long long *)&new_id)) {
3791                 DMWARN("set_transaction_id message: Unrecognised new id %s.", argv[2]);
3792                 return -EINVAL;
3793         }
3794
3795         r = dm_pool_set_metadata_transaction_id(pool->pmd, old_id, new_id);
3796         if (r) {
3797                 DMWARN("Failed to change transaction id from %s to %s.",
3798                        argv[1], argv[2]);
3799                 return r;
3800         }
3801
3802         return 0;
3803 }
3804
3805 static int process_reserve_metadata_snap_mesg(unsigned int argc, char **argv, struct pool *pool)
3806 {
3807         int r;
3808
3809         r = check_arg_count(argc, 1);
3810         if (r)
3811                 return r;
3812
3813         (void) commit(pool);
3814
3815         r = dm_pool_reserve_metadata_snap(pool->pmd);
3816         if (r)
3817                 DMWARN("reserve_metadata_snap message failed.");
3818
3819         return r;
3820 }
3821
3822 static int process_release_metadata_snap_mesg(unsigned int argc, char **argv, struct pool *pool)
3823 {
3824         int r;
3825
3826         r = check_arg_count(argc, 1);
3827         if (r)
3828                 return r;
3829
3830         r = dm_pool_release_metadata_snap(pool->pmd);
3831         if (r)
3832                 DMWARN("release_metadata_snap message failed.");
3833
3834         return r;
3835 }
3836
3837 /*
3838  * Messages supported:
3839  *   create_thin        <dev_id>
3840  *   create_snap        <dev_id> <origin_id>
3841  *   delete             <dev_id>
3842  *   set_transaction_id <current_trans_id> <new_trans_id>
3843  *   reserve_metadata_snap
3844  *   release_metadata_snap
3845  */
3846 static int pool_message(struct dm_target *ti, unsigned int argc, char **argv,
3847                         char *result, unsigned int maxlen)
3848 {
3849         int r = -EINVAL;
3850         struct pool_c *pt = ti->private;
3851         struct pool *pool = pt->pool;
3852
3853         if (get_pool_mode(pool) >= PM_OUT_OF_METADATA_SPACE) {
3854                 DMERR("%s: unable to service pool target messages in READ_ONLY or FAIL mode",
3855                       dm_device_name(pool->pool_md));
3856                 return -EOPNOTSUPP;
3857         }
3858
3859         if (!strcasecmp(argv[0], "create_thin"))
3860                 r = process_create_thin_mesg(argc, argv, pool);
3861
3862         else if (!strcasecmp(argv[0], "create_snap"))
3863                 r = process_create_snap_mesg(argc, argv, pool);
3864
3865         else if (!strcasecmp(argv[0], "delete"))
3866                 r = process_delete_mesg(argc, argv, pool);
3867
3868         else if (!strcasecmp(argv[0], "set_transaction_id"))
3869                 r = process_set_transaction_id_mesg(argc, argv, pool);
3870
3871         else if (!strcasecmp(argv[0], "reserve_metadata_snap"))
3872                 r = process_reserve_metadata_snap_mesg(argc, argv, pool);
3873
3874         else if (!strcasecmp(argv[0], "release_metadata_snap"))
3875                 r = process_release_metadata_snap_mesg(argc, argv, pool);
3876
3877         else
3878                 DMWARN("Unrecognised thin pool target message received: %s", argv[0]);
3879
3880         if (!r)
3881                 (void) commit(pool);
3882
3883         return r;
3884 }
3885
3886 static void emit_flags(struct pool_features *pf, char *result,
3887                        unsigned int sz, unsigned int maxlen)
3888 {
3889         unsigned int count = !pf->zero_new_blocks + !pf->discard_enabled +
3890                 !pf->discard_passdown + (pf->mode == PM_READ_ONLY) +
3891                 pf->error_if_no_space;
3892         DMEMIT("%u ", count);
3893
3894         if (!pf->zero_new_blocks)
3895                 DMEMIT("skip_block_zeroing ");
3896
3897         if (!pf->discard_enabled)
3898                 DMEMIT("ignore_discard ");
3899
3900         if (!pf->discard_passdown)
3901                 DMEMIT("no_discard_passdown ");
3902
3903         if (pf->mode == PM_READ_ONLY)
3904                 DMEMIT("read_only ");
3905
3906         if (pf->error_if_no_space)
3907                 DMEMIT("error_if_no_space ");
3908 }
3909
3910 /*
3911  * Status line is:
3912  *    <transaction id> <used metadata sectors>/<total metadata sectors>
3913  *    <used data sectors>/<total data sectors> <held metadata root>
3914  *    <pool mode> <discard config> <no space config> <needs_check>
3915  */
3916 static void pool_status(struct dm_target *ti, status_type_t type,
3917                         unsigned int status_flags, char *result, unsigned int maxlen)
3918 {
3919         int r;
3920         unsigned int sz = 0;
3921         uint64_t transaction_id;
3922         dm_block_t nr_free_blocks_data;
3923         dm_block_t nr_free_blocks_metadata;
3924         dm_block_t nr_blocks_data;
3925         dm_block_t nr_blocks_metadata;
3926         dm_block_t held_root;
3927         enum pool_mode mode;
3928         char buf[BDEVNAME_SIZE];
3929         char buf2[BDEVNAME_SIZE];
3930         struct pool_c *pt = ti->private;
3931         struct pool *pool = pt->pool;
3932
3933         switch (type) {
3934         case STATUSTYPE_INFO:
3935                 if (get_pool_mode(pool) == PM_FAIL) {
3936                         DMEMIT("Fail");
3937                         break;
3938                 }
3939
3940                 /* Commit to ensure statistics aren't out-of-date */
3941                 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
3942                         (void) commit(pool);
3943
3944                 r = dm_pool_get_metadata_transaction_id(pool->pmd, &transaction_id);
3945                 if (r) {
3946                         DMERR("%s: dm_pool_get_metadata_transaction_id returned %d",
3947                               dm_device_name(pool->pool_md), r);
3948                         goto err;
3949                 }
3950
3951                 r = dm_pool_get_free_metadata_block_count(pool->pmd, &nr_free_blocks_metadata);
3952                 if (r) {
3953                         DMERR("%s: dm_pool_get_free_metadata_block_count returned %d",
3954                               dm_device_name(pool->pool_md), r);
3955                         goto err;
3956                 }
3957
3958                 r = dm_pool_get_metadata_dev_size(pool->pmd, &nr_blocks_metadata);
3959                 if (r) {
3960                         DMERR("%s: dm_pool_get_metadata_dev_size returned %d",
3961                               dm_device_name(pool->pool_md), r);
3962                         goto err;
3963                 }
3964
3965                 r = dm_pool_get_free_block_count(pool->pmd, &nr_free_blocks_data);
3966                 if (r) {
3967                         DMERR("%s: dm_pool_get_free_block_count returned %d",
3968                               dm_device_name(pool->pool_md), r);
3969                         goto err;
3970                 }
3971
3972                 r = dm_pool_get_data_dev_size(pool->pmd, &nr_blocks_data);
3973                 if (r) {
3974                         DMERR("%s: dm_pool_get_data_dev_size returned %d",
3975                               dm_device_name(pool->pool_md), r);
3976                         goto err;
3977                 }
3978
3979                 r = dm_pool_get_metadata_snap(pool->pmd, &held_root);
3980                 if (r) {
3981                         DMERR("%s: dm_pool_get_metadata_snap returned %d",
3982                               dm_device_name(pool->pool_md), r);
3983                         goto err;
3984                 }
3985
3986                 DMEMIT("%llu %llu/%llu %llu/%llu ",
3987                        (unsigned long long)transaction_id,
3988                        (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
3989                        (unsigned long long)nr_blocks_metadata,
3990                        (unsigned long long)(nr_blocks_data - nr_free_blocks_data),
3991                        (unsigned long long)nr_blocks_data);
3992
3993                 if (held_root)
3994                         DMEMIT("%llu ", held_root);
3995                 else
3996                         DMEMIT("- ");
3997
3998                 mode = get_pool_mode(pool);
3999                 if (mode == PM_OUT_OF_DATA_SPACE)
4000                         DMEMIT("out_of_data_space ");
4001                 else if (is_read_only_pool_mode(mode))
4002                         DMEMIT("ro ");
4003                 else
4004                         DMEMIT("rw ");
4005
4006                 if (!pool->pf.discard_enabled)
4007                         DMEMIT("ignore_discard ");
4008                 else if (pool->pf.discard_passdown)
4009                         DMEMIT("discard_passdown ");
4010                 else
4011                         DMEMIT("no_discard_passdown ");
4012
4013                 if (pool->pf.error_if_no_space)
4014                         DMEMIT("error_if_no_space ");
4015                 else
4016                         DMEMIT("queue_if_no_space ");
4017
4018                 if (dm_pool_metadata_needs_check(pool->pmd))
4019                         DMEMIT("needs_check ");
4020                 else
4021                         DMEMIT("- ");
4022
4023                 DMEMIT("%llu ", (unsigned long long)calc_metadata_threshold(pt));
4024
4025                 break;
4026
4027         case STATUSTYPE_TABLE:
4028                 DMEMIT("%s %s %lu %llu ",
4029                        format_dev_t(buf, pt->metadata_dev->bdev->bd_dev),
4030                        format_dev_t(buf2, pt->data_dev->bdev->bd_dev),
4031                        (unsigned long)pool->sectors_per_block,
4032                        (unsigned long long)pt->low_water_blocks);
4033                 emit_flags(&pt->requested_pf, result, sz, maxlen);
4034                 break;
4035
4036         case STATUSTYPE_IMA:
4037                 *result = '\0';
4038                 break;
4039         }
4040         return;
4041
4042 err:
4043         DMEMIT("Error");
4044 }
4045
4046 static int pool_iterate_devices(struct dm_target *ti,
4047                                 iterate_devices_callout_fn fn, void *data)
4048 {
4049         struct pool_c *pt = ti->private;
4050
4051         return fn(ti, pt->data_dev, 0, ti->len, data);
4052 }
4053
4054 static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
4055 {
4056         struct pool_c *pt = ti->private;
4057         struct pool *pool = pt->pool;
4058         sector_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
4059
4060         /*
4061          * If max_sectors is smaller than pool->sectors_per_block adjust it
4062          * to the highest possible power-of-2 factor of pool->sectors_per_block.
4063          * This is especially beneficial when the pool's data device is a RAID
4064          * device that has a full stripe width that matches pool->sectors_per_block
4065          * -- because even though partial RAID stripe-sized IOs will be issued to a
4066          *    single RAID stripe; when aggregated they will end on a full RAID stripe
4067          *    boundary.. which avoids additional partial RAID stripe writes cascading
4068          */
4069         if (limits->max_sectors < pool->sectors_per_block) {
4070                 while (!is_factor(pool->sectors_per_block, limits->max_sectors)) {
4071                         if ((limits->max_sectors & (limits->max_sectors - 1)) == 0)
4072                                 limits->max_sectors--;
4073                         limits->max_sectors = rounddown_pow_of_two(limits->max_sectors);
4074                 }
4075         }
4076
4077         /*
4078          * If the system-determined stacked limits are compatible with the
4079          * pool's blocksize (io_opt is a factor) do not override them.
4080          */
4081         if (io_opt_sectors < pool->sectors_per_block ||
4082             !is_factor(io_opt_sectors, pool->sectors_per_block)) {
4083                 if (is_factor(pool->sectors_per_block, limits->max_sectors))
4084                         blk_limits_io_min(limits, limits->max_sectors << SECTOR_SHIFT);
4085                 else
4086                         blk_limits_io_min(limits, pool->sectors_per_block << SECTOR_SHIFT);
4087                 blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
4088         }
4089
4090         /*
4091          * pt->adjusted_pf is a staging area for the actual features to use.
4092          * They get transferred to the live pool in bind_control_target()
4093          * called from pool_preresume().
4094          */
4095
4096         if (pt->adjusted_pf.discard_enabled) {
4097                 disable_discard_passdown_if_not_supported(pt);
4098                 if (!pt->adjusted_pf.discard_passdown)
4099                         limits->max_discard_sectors = 0;
4100                 /*
4101                  * The pool uses the same discard limits as the underlying data
4102                  * device.  DM core has already set this up.
4103                  */
4104         } else {
4105                 /*
4106                  * Must explicitly disallow stacking discard limits otherwise the
4107                  * block layer will stack them if pool's data device has support.
4108                  */
4109                 limits->discard_granularity = 0;
4110         }
4111 }
4112
4113 static struct target_type pool_target = {
4114         .name = "thin-pool",
4115         .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
4116                     DM_TARGET_IMMUTABLE,
4117         .version = {1, 23, 0},
4118         .module = THIS_MODULE,
4119         .ctr = pool_ctr,
4120         .dtr = pool_dtr,
4121         .map = pool_map,
4122         .presuspend = pool_presuspend,
4123         .presuspend_undo = pool_presuspend_undo,
4124         .postsuspend = pool_postsuspend,
4125         .preresume = pool_preresume,
4126         .resume = pool_resume,
4127         .message = pool_message,
4128         .status = pool_status,
4129         .iterate_devices = pool_iterate_devices,
4130         .io_hints = pool_io_hints,
4131 };
4132
4133 /*
4134  *--------------------------------------------------------------
4135  * Thin target methods
4136  *--------------------------------------------------------------
4137  */
4138 static void thin_get(struct thin_c *tc)
4139 {
4140         refcount_inc(&tc->refcount);
4141 }
4142
4143 static void thin_put(struct thin_c *tc)
4144 {
4145         if (refcount_dec_and_test(&tc->refcount))
4146                 complete(&tc->can_destroy);
4147 }
4148
4149 static void thin_dtr(struct dm_target *ti)
4150 {
4151         struct thin_c *tc = ti->private;
4152
4153         spin_lock_irq(&tc->pool->lock);
4154         list_del_rcu(&tc->list);
4155         spin_unlock_irq(&tc->pool->lock);
4156         synchronize_rcu();
4157
4158         thin_put(tc);
4159         wait_for_completion(&tc->can_destroy);
4160
4161         mutex_lock(&dm_thin_pool_table.mutex);
4162
4163         __pool_dec(tc->pool);
4164         dm_pool_close_thin_device(tc->td);
4165         dm_put_device(ti, tc->pool_dev);
4166         if (tc->origin_dev)
4167                 dm_put_device(ti, tc->origin_dev);
4168         kfree(tc);
4169
4170         mutex_unlock(&dm_thin_pool_table.mutex);
4171 }
4172
4173 /*
4174  * Thin target parameters:
4175  *
4176  * <pool_dev> <dev_id> [origin_dev]
4177  *
4178  * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
4179  * dev_id: the internal device identifier
4180  * origin_dev: a device external to the pool that should act as the origin
4181  *
4182  * If the pool device has discards disabled, they get disabled for the thin
4183  * device as well.
4184  */
4185 static int thin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
4186 {
4187         int r;
4188         struct thin_c *tc;
4189         struct dm_dev *pool_dev, *origin_dev;
4190         struct mapped_device *pool_md;
4191
4192         mutex_lock(&dm_thin_pool_table.mutex);
4193
4194         if (argc != 2 && argc != 3) {
4195                 ti->error = "Invalid argument count";
4196                 r = -EINVAL;
4197                 goto out_unlock;
4198         }
4199
4200         tc = ti->private = kzalloc(sizeof(*tc), GFP_KERNEL);
4201         if (!tc) {
4202                 ti->error = "Out of memory";
4203                 r = -ENOMEM;
4204                 goto out_unlock;
4205         }
4206         tc->thin_md = dm_table_get_md(ti->table);
4207         spin_lock_init(&tc->lock);
4208         INIT_LIST_HEAD(&tc->deferred_cells);
4209         bio_list_init(&tc->deferred_bio_list);
4210         bio_list_init(&tc->retry_on_resume_list);
4211         tc->sort_bio_list = RB_ROOT;
4212
4213         if (argc == 3) {
4214                 if (!strcmp(argv[0], argv[2])) {
4215                         ti->error = "Error setting origin device";
4216                         r = -EINVAL;
4217                         goto bad_origin_dev;
4218                 }
4219
4220                 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &origin_dev);
4221                 if (r) {
4222                         ti->error = "Error opening origin device";
4223                         goto bad_origin_dev;
4224                 }
4225                 tc->origin_dev = origin_dev;
4226         }
4227
4228         r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &pool_dev);
4229         if (r) {
4230                 ti->error = "Error opening pool device";
4231                 goto bad_pool_dev;
4232         }
4233         tc->pool_dev = pool_dev;
4234
4235         if (read_dev_id(argv[1], (unsigned long long *)&tc->dev_id, 0)) {
4236                 ti->error = "Invalid device id";
4237                 r = -EINVAL;
4238                 goto bad_common;
4239         }
4240
4241         pool_md = dm_get_md(tc->pool_dev->bdev->bd_dev);
4242         if (!pool_md) {
4243                 ti->error = "Couldn't get pool mapped device";
4244                 r = -EINVAL;
4245                 goto bad_common;
4246         }
4247
4248         tc->pool = __pool_table_lookup(pool_md);
4249         if (!tc->pool) {
4250                 ti->error = "Couldn't find pool object";
4251                 r = -EINVAL;
4252                 goto bad_pool_lookup;
4253         }
4254         __pool_inc(tc->pool);
4255
4256         if (get_pool_mode(tc->pool) == PM_FAIL) {
4257                 ti->error = "Couldn't open thin device, Pool is in fail mode";
4258                 r = -EINVAL;
4259                 goto bad_pool;
4260         }
4261
4262         r = dm_pool_open_thin_device(tc->pool->pmd, tc->dev_id, &tc->td);
4263         if (r) {
4264                 ti->error = "Couldn't open thin internal device";
4265                 goto bad_pool;
4266         }
4267
4268         r = dm_set_target_max_io_len(ti, tc->pool->sectors_per_block);
4269         if (r)
4270                 goto bad;
4271
4272         ti->num_flush_bios = 1;
4273         ti->limit_swap_bios = true;
4274         ti->flush_supported = true;
4275         ti->accounts_remapped_io = true;
4276         ti->per_io_data_size = sizeof(struct dm_thin_endio_hook);
4277
4278         /* In case the pool supports discards, pass them on. */
4279         if (tc->pool->pf.discard_enabled) {
4280                 ti->discards_supported = true;
4281                 ti->num_discard_bios = 1;
4282                 ti->max_discard_granularity = true;
4283         }
4284
4285         mutex_unlock(&dm_thin_pool_table.mutex);
4286
4287         spin_lock_irq(&tc->pool->lock);
4288         if (tc->pool->suspended) {
4289                 spin_unlock_irq(&tc->pool->lock);
4290                 mutex_lock(&dm_thin_pool_table.mutex); /* reacquire for __pool_dec */
4291                 ti->error = "Unable to activate thin device while pool is suspended";
4292                 r = -EINVAL;
4293                 goto bad;
4294         }
4295         refcount_set(&tc->refcount, 1);
4296         init_completion(&tc->can_destroy);
4297         list_add_tail_rcu(&tc->list, &tc->pool->active_thins);
4298         spin_unlock_irq(&tc->pool->lock);
4299         /*
4300          * This synchronize_rcu() call is needed here otherwise we risk a
4301          * wake_worker() call finding no bios to process (because the newly
4302          * added tc isn't yet visible).  So this reduces latency since we
4303          * aren't then dependent on the periodic commit to wake_worker().
4304          */
4305         synchronize_rcu();
4306
4307         dm_put(pool_md);
4308
4309         return 0;
4310
4311 bad:
4312         dm_pool_close_thin_device(tc->td);
4313 bad_pool:
4314         __pool_dec(tc->pool);
4315 bad_pool_lookup:
4316         dm_put(pool_md);
4317 bad_common:
4318         dm_put_device(ti, tc->pool_dev);
4319 bad_pool_dev:
4320         if (tc->origin_dev)
4321                 dm_put_device(ti, tc->origin_dev);
4322 bad_origin_dev:
4323         kfree(tc);
4324 out_unlock:
4325         mutex_unlock(&dm_thin_pool_table.mutex);
4326
4327         return r;
4328 }
4329
4330 static int thin_map(struct dm_target *ti, struct bio *bio)
4331 {
4332         bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
4333
4334         return thin_bio_map(ti, bio);
4335 }
4336
4337 static int thin_endio(struct dm_target *ti, struct bio *bio,
4338                 blk_status_t *err)
4339 {
4340         unsigned long flags;
4341         struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
4342         struct list_head work;
4343         struct dm_thin_new_mapping *m, *tmp;
4344         struct pool *pool = h->tc->pool;
4345
4346         if (h->shared_read_entry) {
4347                 INIT_LIST_HEAD(&work);
4348                 dm_deferred_entry_dec(h->shared_read_entry, &work);
4349
4350                 spin_lock_irqsave(&pool->lock, flags);
4351                 list_for_each_entry_safe(m, tmp, &work, list) {
4352                         list_del(&m->list);
4353                         __complete_mapping_preparation(m);
4354                 }
4355                 spin_unlock_irqrestore(&pool->lock, flags);
4356         }
4357
4358         if (h->all_io_entry) {
4359                 INIT_LIST_HEAD(&work);
4360                 dm_deferred_entry_dec(h->all_io_entry, &work);
4361                 if (!list_empty(&work)) {
4362                         spin_lock_irqsave(&pool->lock, flags);
4363                         list_for_each_entry_safe(m, tmp, &work, list)
4364                                 list_add_tail(&m->list, &pool->prepared_discards);
4365                         spin_unlock_irqrestore(&pool->lock, flags);
4366                         wake_worker(pool);
4367                 }
4368         }
4369
4370         if (h->cell)
4371                 cell_defer_no_holder(h->tc, h->cell);
4372
4373         return DM_ENDIO_DONE;
4374 }
4375
4376 static void thin_presuspend(struct dm_target *ti)
4377 {
4378         struct thin_c *tc = ti->private;
4379
4380         if (dm_noflush_suspending(ti))
4381                 noflush_work(tc, do_noflush_start);
4382 }
4383
4384 static void thin_postsuspend(struct dm_target *ti)
4385 {
4386         struct thin_c *tc = ti->private;
4387
4388         /*
4389          * The dm_noflush_suspending flag has been cleared by now, so
4390          * unfortunately we must always run this.
4391          */
4392         noflush_work(tc, do_noflush_stop);
4393 }
4394
4395 static int thin_preresume(struct dm_target *ti)
4396 {
4397         struct thin_c *tc = ti->private;
4398
4399         if (tc->origin_dev)
4400                 tc->origin_size = get_dev_size(tc->origin_dev->bdev);
4401
4402         return 0;
4403 }
4404
4405 /*
4406  * <nr mapped sectors> <highest mapped sector>
4407  */
4408 static void thin_status(struct dm_target *ti, status_type_t type,
4409                         unsigned int status_flags, char *result, unsigned int maxlen)
4410 {
4411         int r;
4412         ssize_t sz = 0;
4413         dm_block_t mapped, highest;
4414         char buf[BDEVNAME_SIZE];
4415         struct thin_c *tc = ti->private;
4416
4417         if (get_pool_mode(tc->pool) == PM_FAIL) {
4418                 DMEMIT("Fail");
4419                 return;
4420         }
4421
4422         if (!tc->td)
4423                 DMEMIT("-");
4424         else {
4425                 switch (type) {
4426                 case STATUSTYPE_INFO:
4427                         r = dm_thin_get_mapped_count(tc->td, &mapped);
4428                         if (r) {
4429                                 DMERR("dm_thin_get_mapped_count returned %d", r);
4430                                 goto err;
4431                         }
4432
4433                         r = dm_thin_get_highest_mapped_block(tc->td, &highest);
4434                         if (r < 0) {
4435                                 DMERR("dm_thin_get_highest_mapped_block returned %d", r);
4436                                 goto err;
4437                         }
4438
4439                         DMEMIT("%llu ", mapped * tc->pool->sectors_per_block);
4440                         if (r)
4441                                 DMEMIT("%llu", ((highest + 1) *
4442                                                 tc->pool->sectors_per_block) - 1);
4443                         else
4444                                 DMEMIT("-");
4445                         break;
4446
4447                 case STATUSTYPE_TABLE:
4448                         DMEMIT("%s %lu",
4449                                format_dev_t(buf, tc->pool_dev->bdev->bd_dev),
4450                                (unsigned long) tc->dev_id);
4451                         if (tc->origin_dev)
4452                                 DMEMIT(" %s", format_dev_t(buf, tc->origin_dev->bdev->bd_dev));
4453                         break;
4454
4455                 case STATUSTYPE_IMA:
4456                         *result = '\0';
4457                         break;
4458                 }
4459         }
4460
4461         return;
4462
4463 err:
4464         DMEMIT("Error");
4465 }
4466
4467 static int thin_iterate_devices(struct dm_target *ti,
4468                                 iterate_devices_callout_fn fn, void *data)
4469 {
4470         sector_t blocks;
4471         struct thin_c *tc = ti->private;
4472         struct pool *pool = tc->pool;
4473
4474         /*
4475          * We can't call dm_pool_get_data_dev_size() since that blocks.  So
4476          * we follow a more convoluted path through to the pool's target.
4477          */
4478         if (!pool->ti)
4479                 return 0;       /* nothing is bound */
4480
4481         blocks = pool->ti->len;
4482         (void) sector_div(blocks, pool->sectors_per_block);
4483         if (blocks)
4484                 return fn(ti, tc->pool_dev, 0, pool->sectors_per_block * blocks, data);
4485
4486         return 0;
4487 }
4488
4489 static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
4490 {
4491         struct thin_c *tc = ti->private;
4492         struct pool *pool = tc->pool;
4493
4494         if (pool->pf.discard_enabled) {
4495                 limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
4496                 limits->max_discard_sectors = pool->sectors_per_block * BIO_PRISON_MAX_RANGE;
4497         }
4498 }
4499
4500 static struct target_type thin_target = {
4501         .name = "thin",
4502         .version = {1, 23, 0},
4503         .module = THIS_MODULE,
4504         .ctr = thin_ctr,
4505         .dtr = thin_dtr,
4506         .map = thin_map,
4507         .end_io = thin_endio,
4508         .preresume = thin_preresume,
4509         .presuspend = thin_presuspend,
4510         .postsuspend = thin_postsuspend,
4511         .status = thin_status,
4512         .iterate_devices = thin_iterate_devices,
4513         .io_hints = thin_io_hints,
4514 };
4515
4516 /*----------------------------------------------------------------*/
4517
4518 static int __init dm_thin_init(void)
4519 {
4520         int r = -ENOMEM;
4521
4522         pool_table_init();
4523
4524         _new_mapping_cache = KMEM_CACHE(dm_thin_new_mapping, 0);
4525         if (!_new_mapping_cache)
4526                 return r;
4527
4528         r = dm_register_target(&thin_target);
4529         if (r)
4530                 goto bad_new_mapping_cache;
4531
4532         r = dm_register_target(&pool_target);
4533         if (r)
4534                 goto bad_thin_target;
4535
4536         return 0;
4537
4538 bad_thin_target:
4539         dm_unregister_target(&thin_target);
4540 bad_new_mapping_cache:
4541         kmem_cache_destroy(_new_mapping_cache);
4542
4543         return r;
4544 }
4545
4546 static void dm_thin_exit(void)
4547 {
4548         dm_unregister_target(&thin_target);
4549         dm_unregister_target(&pool_target);
4550
4551         kmem_cache_destroy(_new_mapping_cache);
4552
4553         pool_table_exit();
4554 }
4555
4556 module_init(dm_thin_init);
4557 module_exit(dm_thin_exit);
4558
4559 module_param_named(no_space_timeout, no_space_timeout_secs, uint, 0644);
4560 MODULE_PARM_DESC(no_space_timeout, "Out of data space queue IO timeout in seconds");
4561
4562 MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
4563 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
4564 MODULE_LICENSE("GPL");