linux/drivers/md/dm-thin.c
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   1/*
   2 * Copyright (C) 2011-2012 Red Hat UK.
   3 *
   4 * This file is released under the GPL.
   5 */
   6
   7#include "dm-thin-metadata.h"
   8#include "dm-bio-prison.h"
   9#include "dm.h"
  10
  11#include <linux/device-mapper.h>
  12#include <linux/dm-io.h>
  13#include <linux/dm-kcopyd.h>
  14#include <linux/list.h>
  15#include <linux/init.h>
  16#include <linux/module.h>
  17#include <linux/slab.h>
  18
  19#define DM_MSG_PREFIX   "thin"
  20
  21/*
  22 * Tunable constants
  23 */
  24#define ENDIO_HOOK_POOL_SIZE 1024
  25#define MAPPING_POOL_SIZE 1024
  26#define PRISON_CELLS 1024
  27#define COMMIT_PERIOD HZ
  28
  29DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle,
  30                "A percentage of time allocated for copy on write");
  31
  32/*
  33 * The block size of the device holding pool data must be
  34 * between 64KB and 1GB.
  35 */
  36#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (64 * 1024 >> SECTOR_SHIFT)
  37#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
  38
  39/*
  40 * Device id is restricted to 24 bits.
  41 */
  42#define MAX_DEV_ID ((1 << 24) - 1)
  43
  44/*
  45 * How do we handle breaking sharing of data blocks?
  46 * =================================================
  47 *
  48 * We use a standard copy-on-write btree to store the mappings for the
  49 * devices (note I'm talking about copy-on-write of the metadata here, not
  50 * the data).  When you take an internal snapshot you clone the root node
  51 * of the origin btree.  After this there is no concept of an origin or a
  52 * snapshot.  They are just two device trees that happen to point to the
  53 * same data blocks.
  54 *
  55 * When we get a write in we decide if it's to a shared data block using
  56 * some timestamp magic.  If it is, we have to break sharing.
  57 *
  58 * Let's say we write to a shared block in what was the origin.  The
  59 * steps are:
  60 *
  61 * i) plug io further to this physical block. (see bio_prison code).
  62 *
  63 * ii) quiesce any read io to that shared data block.  Obviously
  64 * including all devices that share this block.  (see dm_deferred_set code)
  65 *
  66 * iii) copy the data block to a newly allocate block.  This step can be
  67 * missed out if the io covers the block. (schedule_copy).
  68 *
  69 * iv) insert the new mapping into the origin's btree
  70 * (process_prepared_mapping).  This act of inserting breaks some
  71 * sharing of btree nodes between the two devices.  Breaking sharing only
  72 * effects the btree of that specific device.  Btrees for the other
  73 * devices that share the block never change.  The btree for the origin
  74 * device as it was after the last commit is untouched, ie. we're using
  75 * persistent data structures in the functional programming sense.
  76 *
  77 * v) unplug io to this physical block, including the io that triggered
  78 * the breaking of sharing.
  79 *
  80 * Steps (ii) and (iii) occur in parallel.
  81 *
  82 * The metadata _doesn't_ need to be committed before the io continues.  We
  83 * get away with this because the io is always written to a _new_ block.
  84 * If there's a crash, then:
  85 *
  86 * - The origin mapping will point to the old origin block (the shared
  87 * one).  This will contain the data as it was before the io that triggered
  88 * the breaking of sharing came in.
  89 *
  90 * - The snap mapping still points to the old block.  As it would after
  91 * the commit.
  92 *
  93 * The downside of this scheme is the timestamp magic isn't perfect, and
  94 * will continue to think that data block in the snapshot device is shared
  95 * even after the write to the origin has broken sharing.  I suspect data
  96 * blocks will typically be shared by many different devices, so we're
  97 * breaking sharing n + 1 times, rather than n, where n is the number of
  98 * devices that reference this data block.  At the moment I think the
  99 * benefits far, far outweigh the disadvantages.
 100 */
 101
 102/*----------------------------------------------------------------*/
 103
 104/*
 105 * Key building.
 106 */
 107static void build_data_key(struct dm_thin_device *td,
 108                           dm_block_t b, struct dm_cell_key *key)
 109{
 110        key->virtual = 0;
 111        key->dev = dm_thin_dev_id(td);
 112        key->block = b;
 113}
 114
 115static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
 116                              struct dm_cell_key *key)
 117{
 118        key->virtual = 1;
 119        key->dev = dm_thin_dev_id(td);
 120        key->block = b;
 121}
 122
 123/*----------------------------------------------------------------*/
 124
 125/*
 126 * A pool device ties together a metadata device and a data device.  It
 127 * also provides the interface for creating and destroying internal
 128 * devices.
 129 */
 130struct dm_thin_new_mapping;
 131
 132/*
 133 * The pool runs in 3 modes.  Ordered in degraded order for comparisons.
 134 */
 135enum pool_mode {
 136        PM_WRITE,               /* metadata may be changed */
 137        PM_READ_ONLY,           /* metadata may not be changed */
 138        PM_FAIL,                /* all I/O fails */
 139};
 140
 141struct pool_features {
 142        enum pool_mode mode;
 143
 144        bool zero_new_blocks:1;
 145        bool discard_enabled:1;
 146        bool discard_passdown:1;
 147};
 148
 149struct thin_c;
 150typedef void (*process_bio_fn)(struct thin_c *tc, struct bio *bio);
 151typedef void (*process_mapping_fn)(struct dm_thin_new_mapping *m);
 152
 153struct pool {
 154        struct list_head list;
 155        struct dm_target *ti;   /* Only set if a pool target is bound */
 156
 157        struct mapped_device *pool_md;
 158        struct block_device *md_dev;
 159        struct dm_pool_metadata *pmd;
 160
 161        dm_block_t low_water_blocks;
 162        uint32_t sectors_per_block;
 163        int sectors_per_block_shift;
 164
 165        struct pool_features pf;
 166        unsigned low_water_triggered:1; /* A dm event has been sent */
 167        unsigned no_free_space:1;       /* A -ENOSPC warning has been issued */
 168
 169        struct dm_bio_prison *prison;
 170        struct dm_kcopyd_client *copier;
 171
 172        struct workqueue_struct *wq;
 173        struct work_struct worker;
 174        struct delayed_work waker;
 175
 176        unsigned long last_commit_jiffies;
 177        unsigned ref_count;
 178
 179        spinlock_t lock;
 180        struct bio_list deferred_bios;
 181        struct bio_list deferred_flush_bios;
 182        struct list_head prepared_mappings;
 183        struct list_head prepared_discards;
 184
 185        struct bio_list retry_on_resume_list;
 186
 187        struct dm_deferred_set *shared_read_ds;
 188        struct dm_deferred_set *all_io_ds;
 189
 190        struct dm_thin_new_mapping *next_mapping;
 191        mempool_t *mapping_pool;
 192
 193        process_bio_fn process_bio;
 194        process_bio_fn process_discard;
 195
 196        process_mapping_fn process_prepared_mapping;
 197        process_mapping_fn process_prepared_discard;
 198};
 199
 200static enum pool_mode get_pool_mode(struct pool *pool);
 201static void set_pool_mode(struct pool *pool, enum pool_mode mode);
 202
 203/*
 204 * Target context for a pool.
 205 */
 206struct pool_c {
 207        struct dm_target *ti;
 208        struct pool *pool;
 209        struct dm_dev *data_dev;
 210        struct dm_dev *metadata_dev;
 211        struct dm_target_callbacks callbacks;
 212
 213        dm_block_t low_water_blocks;
 214        struct pool_features requested_pf; /* Features requested during table load */
 215        struct pool_features adjusted_pf;  /* Features used after adjusting for constituent devices */
 216};
 217
 218/*
 219 * Target context for a thin.
 220 */
 221struct thin_c {
 222        struct dm_dev *pool_dev;
 223        struct dm_dev *origin_dev;
 224        dm_thin_id dev_id;
 225
 226        struct pool *pool;
 227        struct dm_thin_device *td;
 228};
 229
 230/*----------------------------------------------------------------*/
 231
 232/*
 233 * wake_worker() is used when new work is queued and when pool_resume is
 234 * ready to continue deferred IO processing.
 235 */
 236static void wake_worker(struct pool *pool)
 237{
 238        queue_work(pool->wq, &pool->worker);
 239}
 240
 241/*----------------------------------------------------------------*/
 242
 243static int bio_detain(struct pool *pool, struct dm_cell_key *key, struct bio *bio,
 244                      struct dm_bio_prison_cell **cell_result)
 245{
 246        int r;
 247        struct dm_bio_prison_cell *cell_prealloc;
 248
 249        /*
 250         * Allocate a cell from the prison's mempool.
 251         * This might block but it can't fail.
 252         */
 253        cell_prealloc = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);
 254
 255        r = dm_bio_detain(pool->prison, key, bio, cell_prealloc, cell_result);
 256        if (r)
 257                /*
 258                 * We reused an old cell; we can get rid of
 259                 * the new one.
 260                 */
 261                dm_bio_prison_free_cell(pool->prison, cell_prealloc);
 262
 263        return r;
 264}
 265
 266static void cell_release(struct pool *pool,
 267                         struct dm_bio_prison_cell *cell,
 268                         struct bio_list *bios)
 269{
 270        dm_cell_release(pool->prison, cell, bios);
 271        dm_bio_prison_free_cell(pool->prison, cell);
 272}
 273
 274static void cell_release_no_holder(struct pool *pool,
 275                                   struct dm_bio_prison_cell *cell,
 276                                   struct bio_list *bios)
 277{
 278        dm_cell_release_no_holder(pool->prison, cell, bios);
 279        dm_bio_prison_free_cell(pool->prison, cell);
 280}
 281
 282static void cell_defer_no_holder_no_free(struct thin_c *tc,
 283                                         struct dm_bio_prison_cell *cell)
 284{
 285        struct pool *pool = tc->pool;
 286        unsigned long flags;
 287
 288        spin_lock_irqsave(&pool->lock, flags);
 289        dm_cell_release_no_holder(pool->prison, cell, &pool->deferred_bios);
 290        spin_unlock_irqrestore(&pool->lock, flags);
 291
 292        wake_worker(pool);
 293}
 294
 295static void cell_error(struct pool *pool,
 296                       struct dm_bio_prison_cell *cell)
 297{
 298        dm_cell_error(pool->prison, cell);
 299        dm_bio_prison_free_cell(pool->prison, cell);
 300}
 301
 302/*----------------------------------------------------------------*/
 303
 304/*
 305 * A global list of pools that uses a struct mapped_device as a key.
 306 */
 307static struct dm_thin_pool_table {
 308        struct mutex mutex;
 309        struct list_head pools;
 310} dm_thin_pool_table;
 311
 312static void pool_table_init(void)
 313{
 314        mutex_init(&dm_thin_pool_table.mutex);
 315        INIT_LIST_HEAD(&dm_thin_pool_table.pools);
 316}
 317
 318static void __pool_table_insert(struct pool *pool)
 319{
 320        BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 321        list_add(&pool->list, &dm_thin_pool_table.pools);
 322}
 323
 324static void __pool_table_remove(struct pool *pool)
 325{
 326        BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 327        list_del(&pool->list);
 328}
 329
 330static struct pool *__pool_table_lookup(struct mapped_device *md)
 331{
 332        struct pool *pool = NULL, *tmp;
 333
 334        BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 335
 336        list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
 337                if (tmp->pool_md == md) {
 338                        pool = tmp;
 339                        break;
 340                }
 341        }
 342
 343        return pool;
 344}
 345
 346static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev)
 347{
 348        struct pool *pool = NULL, *tmp;
 349
 350        BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
 351
 352        list_for_each_entry(tmp, &dm_thin_pool_table.pools, list) {
 353                if (tmp->md_dev == md_dev) {
 354                        pool = tmp;
 355                        break;
 356                }
 357        }
 358
 359        return pool;
 360}
 361
 362/*----------------------------------------------------------------*/
 363
 364struct dm_thin_endio_hook {
 365        struct thin_c *tc;
 366        struct dm_deferred_entry *shared_read_entry;
 367        struct dm_deferred_entry *all_io_entry;
 368        struct dm_thin_new_mapping *overwrite_mapping;
 369};
 370
 371static void __requeue_bio_list(struct thin_c *tc, struct bio_list *master)
 372{
 373        struct bio *bio;
 374        struct bio_list bios;
 375
 376        bio_list_init(&bios);
 377        bio_list_merge(&bios, master);
 378        bio_list_init(master);
 379
 380        while ((bio = bio_list_pop(&bios))) {
 381                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 382
 383                if (h->tc == tc)
 384                        bio_endio(bio, DM_ENDIO_REQUEUE);
 385                else
 386                        bio_list_add(master, bio);
 387        }
 388}
 389
 390static void requeue_io(struct thin_c *tc)
 391{
 392        struct pool *pool = tc->pool;
 393        unsigned long flags;
 394
 395        spin_lock_irqsave(&pool->lock, flags);
 396        __requeue_bio_list(tc, &pool->deferred_bios);
 397        __requeue_bio_list(tc, &pool->retry_on_resume_list);
 398        spin_unlock_irqrestore(&pool->lock, flags);
 399}
 400
 401/*
 402 * This section of code contains the logic for processing a thin device's IO.
 403 * Much of the code depends on pool object resources (lists, workqueues, etc)
 404 * but most is exclusively called from the thin target rather than the thin-pool
 405 * target.
 406 */
 407
 408static bool block_size_is_power_of_two(struct pool *pool)
 409{
 410        return pool->sectors_per_block_shift >= 0;
 411}
 412
 413static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio)
 414{
 415        struct pool *pool = tc->pool;
 416        sector_t block_nr = bio->bi_sector;
 417
 418        if (block_size_is_power_of_two(pool))
 419                block_nr >>= pool->sectors_per_block_shift;
 420        else
 421                (void) sector_div(block_nr, pool->sectors_per_block);
 422
 423        return block_nr;
 424}
 425
 426static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
 427{
 428        struct pool *pool = tc->pool;
 429        sector_t bi_sector = bio->bi_sector;
 430
 431        bio->bi_bdev = tc->pool_dev->bdev;
 432        if (block_size_is_power_of_two(pool))
 433                bio->bi_sector = (block << pool->sectors_per_block_shift) |
 434                                (bi_sector & (pool->sectors_per_block - 1));
 435        else
 436                bio->bi_sector = (block * pool->sectors_per_block) +
 437                                 sector_div(bi_sector, pool->sectors_per_block);
 438}
 439
 440static void remap_to_origin(struct thin_c *tc, struct bio *bio)
 441{
 442        bio->bi_bdev = tc->origin_dev->bdev;
 443}
 444
 445static int bio_triggers_commit(struct thin_c *tc, struct bio *bio)
 446{
 447        return (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) &&
 448                dm_thin_changed_this_transaction(tc->td);
 449}
 450
 451static void inc_all_io_entry(struct pool *pool, struct bio *bio)
 452{
 453        struct dm_thin_endio_hook *h;
 454
 455        if (bio->bi_rw & REQ_DISCARD)
 456                return;
 457
 458        h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 459        h->all_io_entry = dm_deferred_entry_inc(pool->all_io_ds);
 460}
 461
 462static void issue(struct thin_c *tc, struct bio *bio)
 463{
 464        struct pool *pool = tc->pool;
 465        unsigned long flags;
 466
 467        if (!bio_triggers_commit(tc, bio)) {
 468                generic_make_request(bio);
 469                return;
 470        }
 471
 472        /*
 473         * Complete bio with an error if earlier I/O caused changes to
 474         * the metadata that can't be committed e.g, due to I/O errors
 475         * on the metadata device.
 476         */
 477        if (dm_thin_aborted_changes(tc->td)) {
 478                bio_io_error(bio);
 479                return;
 480        }
 481
 482        /*
 483         * Batch together any bios that trigger commits and then issue a
 484         * single commit for them in process_deferred_bios().
 485         */
 486        spin_lock_irqsave(&pool->lock, flags);
 487        bio_list_add(&pool->deferred_flush_bios, bio);
 488        spin_unlock_irqrestore(&pool->lock, flags);
 489}
 490
 491static void remap_to_origin_and_issue(struct thin_c *tc, struct bio *bio)
 492{
 493        remap_to_origin(tc, bio);
 494        issue(tc, bio);
 495}
 496
 497static void remap_and_issue(struct thin_c *tc, struct bio *bio,
 498                            dm_block_t block)
 499{
 500        remap(tc, bio, block);
 501        issue(tc, bio);
 502}
 503
 504/*----------------------------------------------------------------*/
 505
 506/*
 507 * Bio endio functions.
 508 */
 509struct dm_thin_new_mapping {
 510        struct list_head list;
 511
 512        unsigned quiesced:1;
 513        unsigned prepared:1;
 514        unsigned pass_discard:1;
 515
 516        struct thin_c *tc;
 517        dm_block_t virt_block;
 518        dm_block_t data_block;
 519        struct dm_bio_prison_cell *cell, *cell2;
 520        int err;
 521
 522        /*
 523         * If the bio covers the whole area of a block then we can avoid
 524         * zeroing or copying.  Instead this bio is hooked.  The bio will
 525         * still be in the cell, so care has to be taken to avoid issuing
 526         * the bio twice.
 527         */
 528        struct bio *bio;
 529        bio_end_io_t *saved_bi_end_io;
 530};
 531
 532static void __maybe_add_mapping(struct dm_thin_new_mapping *m)
 533{
 534        struct pool *pool = m->tc->pool;
 535
 536        if (m->quiesced && m->prepared) {
 537                list_add(&m->list, &pool->prepared_mappings);
 538                wake_worker(pool);
 539        }
 540}
 541
 542static void copy_complete(int read_err, unsigned long write_err, void *context)
 543{
 544        unsigned long flags;
 545        struct dm_thin_new_mapping *m = context;
 546        struct pool *pool = m->tc->pool;
 547
 548        m->err = read_err || write_err ? -EIO : 0;
 549
 550        spin_lock_irqsave(&pool->lock, flags);
 551        m->prepared = 1;
 552        __maybe_add_mapping(m);
 553        spin_unlock_irqrestore(&pool->lock, flags);
 554}
 555
 556static void overwrite_endio(struct bio *bio, int err)
 557{
 558        unsigned long flags;
 559        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 560        struct dm_thin_new_mapping *m = h->overwrite_mapping;
 561        struct pool *pool = m->tc->pool;
 562
 563        m->err = err;
 564
 565        spin_lock_irqsave(&pool->lock, flags);
 566        m->prepared = 1;
 567        __maybe_add_mapping(m);
 568        spin_unlock_irqrestore(&pool->lock, flags);
 569}
 570
 571/*----------------------------------------------------------------*/
 572
 573/*
 574 * Workqueue.
 575 */
 576
 577/*
 578 * Prepared mapping jobs.
 579 */
 580
 581/*
 582 * This sends the bios in the cell back to the deferred_bios list.
 583 */
 584static void cell_defer(struct thin_c *tc, struct dm_bio_prison_cell *cell)
 585{
 586        struct pool *pool = tc->pool;
 587        unsigned long flags;
 588
 589        spin_lock_irqsave(&pool->lock, flags);
 590        cell_release(pool, cell, &pool->deferred_bios);
 591        spin_unlock_irqrestore(&tc->pool->lock, flags);
 592
 593        wake_worker(pool);
 594}
 595
 596/*
 597 * Same as cell_defer above, except it omits the original holder of the cell.
 598 */
 599static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
 600{
 601        struct pool *pool = tc->pool;
 602        unsigned long flags;
 603
 604        spin_lock_irqsave(&pool->lock, flags);
 605        cell_release_no_holder(pool, cell, &pool->deferred_bios);
 606        spin_unlock_irqrestore(&pool->lock, flags);
 607
 608        wake_worker(pool);
 609}
 610
 611static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
 612{
 613        if (m->bio)
 614                m->bio->bi_end_io = m->saved_bi_end_io;
 615        cell_error(m->tc->pool, m->cell);
 616        list_del(&m->list);
 617        mempool_free(m, m->tc->pool->mapping_pool);
 618}
 619
 620static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 621{
 622        struct thin_c *tc = m->tc;
 623        struct pool *pool = tc->pool;
 624        struct bio *bio;
 625        int r;
 626
 627        bio = m->bio;
 628        if (bio)
 629                bio->bi_end_io = m->saved_bi_end_io;
 630
 631        if (m->err) {
 632                cell_error(pool, m->cell);
 633                goto out;
 634        }
 635
 636        /*
 637         * Commit the prepared block into the mapping btree.
 638         * Any I/O for this block arriving after this point will get
 639         * remapped to it directly.
 640         */
 641        r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
 642        if (r) {
 643                DMERR_LIMIT("dm_thin_insert_block() failed");
 644                cell_error(pool, m->cell);
 645                goto out;
 646        }
 647
 648        /*
 649         * Release any bios held while the block was being provisioned.
 650         * If we are processing a write bio that completely covers the block,
 651         * we already processed it so can ignore it now when processing
 652         * the bios in the cell.
 653         */
 654        if (bio) {
 655                cell_defer_no_holder(tc, m->cell);
 656                bio_endio(bio, 0);
 657        } else
 658                cell_defer(tc, m->cell);
 659
 660out:
 661        list_del(&m->list);
 662        mempool_free(m, pool->mapping_pool);
 663}
 664
 665static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
 666{
 667        struct thin_c *tc = m->tc;
 668
 669        bio_io_error(m->bio);
 670        cell_defer_no_holder(tc, m->cell);
 671        cell_defer_no_holder(tc, m->cell2);
 672        mempool_free(m, tc->pool->mapping_pool);
 673}
 674
 675static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
 676{
 677        struct thin_c *tc = m->tc;
 678
 679        inc_all_io_entry(tc->pool, m->bio);
 680        cell_defer_no_holder(tc, m->cell);
 681        cell_defer_no_holder(tc, m->cell2);
 682
 683        if (m->pass_discard)
 684                remap_and_issue(tc, m->bio, m->data_block);
 685        else
 686                bio_endio(m->bio, 0);
 687
 688        mempool_free(m, tc->pool->mapping_pool);
 689}
 690
 691static void process_prepared_discard(struct dm_thin_new_mapping *m)
 692{
 693        int r;
 694        struct thin_c *tc = m->tc;
 695
 696        r = dm_thin_remove_block(tc->td, m->virt_block);
 697        if (r)
 698                DMERR_LIMIT("dm_thin_remove_block() failed");
 699
 700        process_prepared_discard_passdown(m);
 701}
 702
 703static void process_prepared(struct pool *pool, struct list_head *head,
 704                             process_mapping_fn *fn)
 705{
 706        unsigned long flags;
 707        struct list_head maps;
 708        struct dm_thin_new_mapping *m, *tmp;
 709
 710        INIT_LIST_HEAD(&maps);
 711        spin_lock_irqsave(&pool->lock, flags);
 712        list_splice_init(head, &maps);
 713        spin_unlock_irqrestore(&pool->lock, flags);
 714
 715        list_for_each_entry_safe(m, tmp, &maps, list)
 716                (*fn)(m);
 717}
 718
 719/*
 720 * Deferred bio jobs.
 721 */
 722static int io_overlaps_block(struct pool *pool, struct bio *bio)
 723{
 724        return bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT);
 725}
 726
 727static int io_overwrites_block(struct pool *pool, struct bio *bio)
 728{
 729        return (bio_data_dir(bio) == WRITE) &&
 730                io_overlaps_block(pool, bio);
 731}
 732
 733static void save_and_set_endio(struct bio *bio, bio_end_io_t **save,
 734                               bio_end_io_t *fn)
 735{
 736        *save = bio->bi_end_io;
 737        bio->bi_end_io = fn;
 738}
 739
 740static int ensure_next_mapping(struct pool *pool)
 741{
 742        if (pool->next_mapping)
 743                return 0;
 744
 745        pool->next_mapping = mempool_alloc(pool->mapping_pool, GFP_ATOMIC);
 746
 747        return pool->next_mapping ? 0 : -ENOMEM;
 748}
 749
 750static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool)
 751{
 752        struct dm_thin_new_mapping *r = pool->next_mapping;
 753
 754        BUG_ON(!pool->next_mapping);
 755
 756        pool->next_mapping = NULL;
 757
 758        return r;
 759}
 760
 761static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
 762                          struct dm_dev *origin, dm_block_t data_origin,
 763                          dm_block_t data_dest,
 764                          struct dm_bio_prison_cell *cell, struct bio *bio)
 765{
 766        int r;
 767        struct pool *pool = tc->pool;
 768        struct dm_thin_new_mapping *m = get_next_mapping(pool);
 769
 770        INIT_LIST_HEAD(&m->list);
 771        m->quiesced = 0;
 772        m->prepared = 0;
 773        m->tc = tc;
 774        m->virt_block = virt_block;
 775        m->data_block = data_dest;
 776        m->cell = cell;
 777        m->err = 0;
 778        m->bio = NULL;
 779
 780        if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
 781                m->quiesced = 1;
 782
 783        /*
 784         * IO to pool_dev remaps to the pool target's data_dev.
 785         *
 786         * If the whole block of data is being overwritten, we can issue the
 787         * bio immediately. Otherwise we use kcopyd to clone the data first.
 788         */
 789        if (io_overwrites_block(pool, bio)) {
 790                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 791
 792                h->overwrite_mapping = m;
 793                m->bio = bio;
 794                save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
 795                inc_all_io_entry(pool, bio);
 796                remap_and_issue(tc, bio, data_dest);
 797        } else {
 798                struct dm_io_region from, to;
 799
 800                from.bdev = origin->bdev;
 801                from.sector = data_origin * pool->sectors_per_block;
 802                from.count = pool->sectors_per_block;
 803
 804                to.bdev = tc->pool_dev->bdev;
 805                to.sector = data_dest * pool->sectors_per_block;
 806                to.count = pool->sectors_per_block;
 807
 808                r = dm_kcopyd_copy(pool->copier, &from, 1, &to,
 809                                   0, copy_complete, m);
 810                if (r < 0) {
 811                        mempool_free(m, pool->mapping_pool);
 812                        DMERR_LIMIT("dm_kcopyd_copy() failed");
 813                        cell_error(pool, cell);
 814                }
 815        }
 816}
 817
 818static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,
 819                                   dm_block_t data_origin, dm_block_t data_dest,
 820                                   struct dm_bio_prison_cell *cell, struct bio *bio)
 821{
 822        schedule_copy(tc, virt_block, tc->pool_dev,
 823                      data_origin, data_dest, cell, bio);
 824}
 825
 826static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,
 827                                   dm_block_t data_dest,
 828                                   struct dm_bio_prison_cell *cell, struct bio *bio)
 829{
 830        schedule_copy(tc, virt_block, tc->origin_dev,
 831                      virt_block, data_dest, cell, bio);
 832}
 833
 834static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
 835                          dm_block_t data_block, struct dm_bio_prison_cell *cell,
 836                          struct bio *bio)
 837{
 838        struct pool *pool = tc->pool;
 839        struct dm_thin_new_mapping *m = get_next_mapping(pool);
 840
 841        INIT_LIST_HEAD(&m->list);
 842        m->quiesced = 1;
 843        m->prepared = 0;
 844        m->tc = tc;
 845        m->virt_block = virt_block;
 846        m->data_block = data_block;
 847        m->cell = cell;
 848        m->err = 0;
 849        m->bio = NULL;
 850
 851        /*
 852         * If the whole block of data is being overwritten or we are not
 853         * zeroing pre-existing data, we can issue the bio immediately.
 854         * Otherwise we use kcopyd to zero the data first.
 855         */
 856        if (!pool->pf.zero_new_blocks)
 857                process_prepared_mapping(m);
 858
 859        else if (io_overwrites_block(pool, bio)) {
 860                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 861
 862                h->overwrite_mapping = m;
 863                m->bio = bio;
 864                save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
 865                inc_all_io_entry(pool, bio);
 866                remap_and_issue(tc, bio, data_block);
 867        } else {
 868                int r;
 869                struct dm_io_region to;
 870
 871                to.bdev = tc->pool_dev->bdev;
 872                to.sector = data_block * pool->sectors_per_block;
 873                to.count = pool->sectors_per_block;
 874
 875                r = dm_kcopyd_zero(pool->copier, 1, &to, 0, copy_complete, m);
 876                if (r < 0) {
 877                        mempool_free(m, pool->mapping_pool);
 878                        DMERR_LIMIT("dm_kcopyd_zero() failed");
 879                        cell_error(pool, cell);
 880                }
 881        }
 882}
 883
 884static int commit(struct pool *pool)
 885{
 886        int r;
 887
 888        r = dm_pool_commit_metadata(pool->pmd);
 889        if (r)
 890                DMERR_LIMIT("commit failed: error = %d", r);
 891
 892        return r;
 893}
 894
 895/*
 896 * A non-zero return indicates read_only or fail_io mode.
 897 * Many callers don't care about the return value.
 898 */
 899static int commit_or_fallback(struct pool *pool)
 900{
 901        int r;
 902
 903        if (get_pool_mode(pool) != PM_WRITE)
 904                return -EINVAL;
 905
 906        r = commit(pool);
 907        if (r)
 908                set_pool_mode(pool, PM_READ_ONLY);
 909
 910        return r;
 911}
 912
 913static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
 914{
 915        int r;
 916        dm_block_t free_blocks;
 917        unsigned long flags;
 918        struct pool *pool = tc->pool;
 919
 920        r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
 921        if (r)
 922                return r;
 923
 924        if (free_blocks <= pool->low_water_blocks && !pool->low_water_triggered) {
 925                DMWARN("%s: reached low water mark for data device: sending event.",
 926                       dm_device_name(pool->pool_md));
 927                spin_lock_irqsave(&pool->lock, flags);
 928                pool->low_water_triggered = 1;
 929                spin_unlock_irqrestore(&pool->lock, flags);
 930                dm_table_event(pool->ti->table);
 931        }
 932
 933        if (!free_blocks) {
 934                if (pool->no_free_space)
 935                        return -ENOSPC;
 936                else {
 937                        /*
 938                         * Try to commit to see if that will free up some
 939                         * more space.
 940                         */
 941                        (void) commit_or_fallback(pool);
 942
 943                        r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
 944                        if (r)
 945                                return r;
 946
 947                        /*
 948                         * If we still have no space we set a flag to avoid
 949                         * doing all this checking and return -ENOSPC.
 950                         */
 951                        if (!free_blocks) {
 952                                DMWARN("%s: no free space available.",
 953                                       dm_device_name(pool->pool_md));
 954                                spin_lock_irqsave(&pool->lock, flags);
 955                                pool->no_free_space = 1;
 956                                spin_unlock_irqrestore(&pool->lock, flags);
 957                                return -ENOSPC;
 958                        }
 959                }
 960        }
 961
 962        r = dm_pool_alloc_data_block(pool->pmd, result);
 963        if (r)
 964                return r;
 965
 966        return 0;
 967}
 968
 969/*
 970 * If we have run out of space, queue bios until the device is
 971 * resumed, presumably after having been reloaded with more space.
 972 */
 973static void retry_on_resume(struct bio *bio)
 974{
 975        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 976        struct thin_c *tc = h->tc;
 977        struct pool *pool = tc->pool;
 978        unsigned long flags;
 979
 980        spin_lock_irqsave(&pool->lock, flags);
 981        bio_list_add(&pool->retry_on_resume_list, bio);
 982        spin_unlock_irqrestore(&pool->lock, flags);
 983}
 984
 985static void no_space(struct pool *pool, struct dm_bio_prison_cell *cell)
 986{
 987        struct bio *bio;
 988        struct bio_list bios;
 989
 990        bio_list_init(&bios);
 991        cell_release(pool, cell, &bios);
 992
 993        while ((bio = bio_list_pop(&bios)))
 994                retry_on_resume(bio);
 995}
 996
 997static void process_discard(struct thin_c *tc, struct bio *bio)
 998{
 999        int r;
1000        unsigned long flags;
1001        struct pool *pool = tc->pool;
1002        struct dm_bio_prison_cell *cell, *cell2;
1003        struct dm_cell_key key, key2;
1004        dm_block_t block = get_bio_block(tc, bio);
1005        struct dm_thin_lookup_result lookup_result;
1006        struct dm_thin_new_mapping *m;
1007
1008        build_virtual_key(tc->td, block, &key);
1009        if (bio_detain(tc->pool, &key, bio, &cell))
1010                return;
1011
1012        r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
1013        switch (r) {
1014        case 0:
1015                /*
1016                 * Check nobody is fiddling with this pool block.  This can
1017                 * happen if someone's in the process of breaking sharing
1018                 * on this block.
1019                 */
1020                build_data_key(tc->td, lookup_result.block, &key2);
1021                if (bio_detain(tc->pool, &key2, bio, &cell2)) {
1022                        cell_defer_no_holder(tc, cell);
1023                        break;
1024                }
1025
1026                if (io_overlaps_block(pool, bio)) {
1027                        /*
1028                         * IO may still be going to the destination block.  We must
1029                         * quiesce before we can do the removal.
1030                         */
1031                        m = get_next_mapping(pool);
1032                        m->tc = tc;
1033                        m->pass_discard = (!lookup_result.shared) && pool->pf.discard_passdown;
1034                        m->virt_block = block;
1035                        m->data_block = lookup_result.block;
1036                        m->cell = cell;
1037                        m->cell2 = cell2;
1038                        m->err = 0;
1039                        m->bio = bio;
1040
1041                        if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) {
1042                                spin_lock_irqsave(&pool->lock, flags);
1043                                list_add(&m->list, &pool->prepared_discards);
1044                                spin_unlock_irqrestore(&pool->lock, flags);
1045                                wake_worker(pool);
1046                        }
1047                } else {
1048                        inc_all_io_entry(pool, bio);
1049                        cell_defer_no_holder(tc, cell);
1050                        cell_defer_no_holder(tc, cell2);
1051
1052                        /*
1053                         * The DM core makes sure that the discard doesn't span
1054                         * a block boundary.  So we submit the discard of a
1055                         * partial block appropriately.
1056                         */
1057                        if ((!lookup_result.shared) && pool->pf.discard_passdown)
1058                                remap_and_issue(tc, bio, lookup_result.block);
1059                        else
1060                                bio_endio(bio, 0);
1061                }
1062                break;
1063
1064        case -ENODATA:
1065                /*
1066                 * It isn't provisioned, just forget it.
1067                 */
1068                cell_defer_no_holder(tc, cell);
1069                bio_endio(bio, 0);
1070                break;
1071
1072        default:
1073                DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
1074                            __func__, r);
1075                cell_defer_no_holder(tc, cell);
1076                bio_io_error(bio);
1077                break;
1078        }
1079}
1080
1081static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
1082                          struct dm_cell_key *key,
1083                          struct dm_thin_lookup_result *lookup_result,
1084                          struct dm_bio_prison_cell *cell)
1085{
1086        int r;
1087        dm_block_t data_block;
1088
1089        r = alloc_data_block(tc, &data_block);
1090        switch (r) {
1091        case 0:
1092                schedule_internal_copy(tc, block, lookup_result->block,
1093                                       data_block, cell, bio);
1094                break;
1095
1096        case -ENOSPC:
1097                no_space(tc->pool, cell);
1098                break;
1099
1100        default:
1101                DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
1102                            __func__, r);
1103                cell_error(tc->pool, cell);
1104                break;
1105        }
1106}
1107
1108static void process_shared_bio(struct thin_c *tc, struct bio *bio,
1109                               dm_block_t block,
1110                               struct dm_thin_lookup_result *lookup_result)
1111{
1112        struct dm_bio_prison_cell *cell;
1113        struct pool *pool = tc->pool;
1114        struct dm_cell_key key;
1115
1116        /*
1117         * If cell is already occupied, then sharing is already in the process
1118         * of being broken so we have nothing further to do here.
1119         */
1120        build_data_key(tc->td, lookup_result->block, &key);
1121        if (bio_detain(pool, &key, bio, &cell))
1122                return;
1123
1124        if (bio_data_dir(bio) == WRITE && bio->bi_size)
1125                break_sharing(tc, bio, block, &key, lookup_result, cell);
1126        else {
1127                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1128
1129                h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
1130                inc_all_io_entry(pool, bio);
1131                cell_defer_no_holder(tc, cell);
1132
1133                remap_and_issue(tc, bio, lookup_result->block);
1134        }
1135}
1136
1137static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block,
1138                            struct dm_bio_prison_cell *cell)
1139{
1140        int r;
1141        dm_block_t data_block;
1142        struct pool *pool = tc->pool;
1143
1144        /*
1145         * Remap empty bios (flushes) immediately, without provisioning.
1146         */
1147        if (!bio->bi_size) {
1148                inc_all_io_entry(pool, bio);
1149                cell_defer_no_holder(tc, cell);
1150
1151                remap_and_issue(tc, bio, 0);
1152                return;
1153        }
1154
1155        /*
1156         * Fill read bios with zeroes and complete them immediately.
1157         */
1158        if (bio_data_dir(bio) == READ) {
1159                zero_fill_bio(bio);
1160                cell_defer_no_holder(tc, cell);
1161                bio_endio(bio, 0);
1162                return;
1163        }
1164
1165        r = alloc_data_block(tc, &data_block);
1166        switch (r) {
1167        case 0:
1168                if (tc->origin_dev)
1169                        schedule_external_copy(tc, block, data_block, cell, bio);
1170                else
1171                        schedule_zero(tc, block, data_block, cell, bio);
1172                break;
1173
1174        case -ENOSPC:
1175                no_space(pool, cell);
1176                break;
1177
1178        default:
1179                DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
1180                            __func__, r);
1181                set_pool_mode(pool, PM_READ_ONLY);
1182                cell_error(pool, cell);
1183                break;
1184        }
1185}
1186
1187static void process_bio(struct thin_c *tc, struct bio *bio)
1188{
1189        int r;
1190        struct pool *pool = tc->pool;
1191        dm_block_t block = get_bio_block(tc, bio);
1192        struct dm_bio_prison_cell *cell;
1193        struct dm_cell_key key;
1194        struct dm_thin_lookup_result lookup_result;
1195
1196        /*
1197         * If cell is already occupied, then the block is already
1198         * being provisioned so we have nothing further to do here.
1199         */
1200        build_virtual_key(tc->td, block, &key);
1201        if (bio_detain(pool, &key, bio, &cell))
1202                return;
1203
1204        r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
1205        switch (r) {
1206        case 0:
1207                if (lookup_result.shared) {
1208                        process_shared_bio(tc, bio, block, &lookup_result);
1209                        cell_defer_no_holder(tc, cell); /* FIXME: pass this cell into process_shared? */
1210                } else {
1211                        inc_all_io_entry(pool, bio);
1212                        cell_defer_no_holder(tc, cell);
1213
1214                        remap_and_issue(tc, bio, lookup_result.block);
1215                }
1216                break;
1217
1218        case -ENODATA:
1219                if (bio_data_dir(bio) == READ && tc->origin_dev) {
1220                        inc_all_io_entry(pool, bio);
1221                        cell_defer_no_holder(tc, cell);
1222
1223                        remap_to_origin_and_issue(tc, bio);
1224                } else
1225                        provision_block(tc, bio, block, cell);
1226                break;
1227
1228        default:
1229                DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
1230                            __func__, r);
1231                cell_defer_no_holder(tc, cell);
1232                bio_io_error(bio);
1233                break;
1234        }
1235}
1236
1237static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
1238{
1239        int r;
1240        int rw = bio_data_dir(bio);
1241        dm_block_t block = get_bio_block(tc, bio);
1242        struct dm_thin_lookup_result lookup_result;
1243
1244        r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
1245        switch (r) {
1246        case 0:
1247                if (lookup_result.shared && (rw == WRITE) && bio->bi_size)
1248                        bio_io_error(bio);
1249                else {
1250                        inc_all_io_entry(tc->pool, bio);
1251                        remap_and_issue(tc, bio, lookup_result.block);
1252                }
1253                break;
1254
1255        case -ENODATA:
1256                if (rw != READ) {
1257                        bio_io_error(bio);
1258                        break;
1259                }
1260
1261                if (tc->origin_dev) {
1262                        inc_all_io_entry(tc->pool, bio);
1263                        remap_to_origin_and_issue(tc, bio);
1264                        break;
1265                }
1266
1267                zero_fill_bio(bio);
1268                bio_endio(bio, 0);
1269                break;
1270
1271        default:
1272                DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
1273                            __func__, r);
1274                bio_io_error(bio);
1275                break;
1276        }
1277}
1278
1279static void process_bio_fail(struct thin_c *tc, struct bio *bio)
1280{
1281        bio_io_error(bio);
1282}
1283
1284/*
1285 * FIXME: should we also commit due to size of transaction, measured in
1286 * metadata blocks?
1287 */
1288static int need_commit_due_to_time(struct pool *pool)
1289{
1290        return jiffies < pool->last_commit_jiffies ||
1291               jiffies > pool->last_commit_jiffies + COMMIT_PERIOD;
1292}
1293
1294static void process_deferred_bios(struct pool *pool)
1295{
1296        unsigned long flags;
1297        struct bio *bio;
1298        struct bio_list bios;
1299
1300        bio_list_init(&bios);
1301
1302        spin_lock_irqsave(&pool->lock, flags);
1303        bio_list_merge(&bios, &pool->deferred_bios);
1304        bio_list_init(&pool->deferred_bios);
1305        spin_unlock_irqrestore(&pool->lock, flags);
1306
1307        while ((bio = bio_list_pop(&bios))) {
1308                struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1309                struct thin_c *tc = h->tc;
1310
1311                /*
1312                 * If we've got no free new_mapping structs, and processing
1313                 * this bio might require one, we pause until there are some
1314                 * prepared mappings to process.
1315                 */
1316                if (ensure_next_mapping(pool)) {
1317                        spin_lock_irqsave(&pool->lock, flags);
1318                        bio_list_merge(&pool->deferred_bios, &bios);
1319                        spin_unlock_irqrestore(&pool->lock, flags);
1320
1321                        break;
1322                }
1323
1324                if (bio->bi_rw & REQ_DISCARD)
1325                        pool->process_discard(tc, bio);
1326                else
1327                        pool->process_bio(tc, bio);
1328        }
1329
1330        /*
1331         * If there are any deferred flush bios, we must commit
1332         * the metadata before issuing them.
1333         */
1334        bio_list_init(&bios);
1335        spin_lock_irqsave(&pool->lock, flags);
1336        bio_list_merge(&bios, &pool->deferred_flush_bios);
1337        bio_list_init(&pool->deferred_flush_bios);
1338        spin_unlock_irqrestore(&pool->lock, flags);
1339
1340        if (bio_list_empty(&bios) && !need_commit_due_to_time(pool))
1341                return;
1342
1343        if (commit_or_fallback(pool)) {
1344                while ((bio = bio_list_pop(&bios)))
1345                        bio_io_error(bio);
1346                return;
1347        }
1348        pool->last_commit_jiffies = jiffies;
1349
1350        while ((bio = bio_list_pop(&bios)))
1351                generic_make_request(bio);
1352}
1353
1354static void do_worker(struct work_struct *ws)
1355{
1356        struct pool *pool = container_of(ws, struct pool, worker);
1357
1358        process_prepared(pool, &pool->prepared_mappings, &pool->process_prepared_mapping);
1359        process_prepared(pool, &pool->prepared_discards, &pool->process_prepared_discard);
1360        process_deferred_bios(pool);
1361}
1362
1363/*
1364 * We want to commit periodically so that not too much
1365 * unwritten data builds up.
1366 */
1367static void do_waker(struct work_struct *ws)
1368{
1369        struct pool *pool = container_of(to_delayed_work(ws), struct pool, waker);
1370        wake_worker(pool);
1371        queue_delayed_work(pool->wq, &pool->waker, COMMIT_PERIOD);
1372}
1373
1374/*----------------------------------------------------------------*/
1375
1376static enum pool_mode get_pool_mode(struct pool *pool)
1377{
1378        return pool->pf.mode;
1379}
1380
1381static void set_pool_mode(struct pool *pool, enum pool_mode mode)
1382{
1383        int r;
1384
1385        pool->pf.mode = mode;
1386
1387        switch (mode) {
1388        case PM_FAIL:
1389                DMERR("switching pool to failure mode");
1390                pool->process_bio = process_bio_fail;
1391                pool->process_discard = process_bio_fail;
1392                pool->process_prepared_mapping = process_prepared_mapping_fail;
1393                pool->process_prepared_discard = process_prepared_discard_fail;
1394                break;
1395
1396        case PM_READ_ONLY:
1397                DMERR("switching pool to read-only mode");
1398                r = dm_pool_abort_metadata(pool->pmd);
1399                if (r) {
1400                        DMERR("aborting transaction failed");
1401                        set_pool_mode(pool, PM_FAIL);
1402                } else {
1403                        dm_pool_metadata_read_only(pool->pmd);
1404                        pool->process_bio = process_bio_read_only;
1405                        pool->process_discard = process_discard;
1406                        pool->process_prepared_mapping = process_prepared_mapping_fail;
1407                        pool->process_prepared_discard = process_prepared_discard_passdown;
1408                }
1409                break;
1410
1411        case PM_WRITE:
1412                pool->process_bio = process_bio;
1413                pool->process_discard = process_discard;
1414                pool->process_prepared_mapping = process_prepared_mapping;
1415                pool->process_prepared_discard = process_prepared_discard;
1416                break;
1417        }
1418}
1419
1420/*----------------------------------------------------------------*/
1421
1422/*
1423 * Mapping functions.
1424 */
1425
1426/*
1427 * Called only while mapping a thin bio to hand it over to the workqueue.
1428 */
1429static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
1430{
1431        unsigned long flags;
1432        struct pool *pool = tc->pool;
1433
1434        spin_lock_irqsave(&pool->lock, flags);
1435        bio_list_add(&pool->deferred_bios, bio);
1436        spin_unlock_irqrestore(&pool->lock, flags);
1437
1438        wake_worker(pool);
1439}
1440
1441static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
1442{
1443        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
1444
1445        h->tc = tc;
1446        h->shared_read_entry = NULL;
1447        h->all_io_entry = NULL;
1448        h->overwrite_mapping = NULL;
1449}
1450
1451/*
1452 * Non-blocking function called from the thin target's map function.
1453 */
1454static int thin_bio_map(struct dm_target *ti, struct bio *bio)
1455{
1456        int r;
1457        struct thin_c *tc = ti->private;
1458        dm_block_t block = get_bio_block(tc, bio);
1459        struct dm_thin_device *td = tc->td;
1460        struct dm_thin_lookup_result result;
1461        struct dm_bio_prison_cell cell1, cell2;
1462        struct dm_bio_prison_cell *cell_result;
1463        struct dm_cell_key key;
1464
1465        thin_hook_bio(tc, bio);
1466
1467        if (get_pool_mode(tc->pool) == PM_FAIL) {
1468                bio_io_error(bio);
1469                return DM_MAPIO_SUBMITTED;
1470        }
1471
1472        if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA)) {
1473                thin_defer_bio(tc, bio);
1474                return DM_MAPIO_SUBMITTED;
1475        }
1476
1477        r = dm_thin_find_block(td, block, 0, &result);
1478
1479        /*
1480         * Note that we defer readahead too.
1481         */
1482        switch (r) {
1483        case 0:
1484                if (unlikely(result.shared)) {
1485                        /*
1486                         * We have a race condition here between the
1487                         * result.shared value returned by the lookup and
1488                         * snapshot creation, which may cause new
1489                         * sharing.
1490                         *
1491                         * To avoid this always quiesce the origin before
1492                         * taking the snap.  You want to do this anyway to
1493                         * ensure a consistent application view
1494                         * (i.e. lockfs).
1495                         *
1496                         * More distant ancestors are irrelevant. The
1497                         * shared flag will be set in their case.
1498                         */
1499                        thin_defer_bio(tc, bio);
1500                        return DM_MAPIO_SUBMITTED;
1501                }
1502
1503                build_virtual_key(tc->td, block, &key);
1504                if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1, &cell_result))
1505                        return DM_MAPIO_SUBMITTED;
1506
1507                build_data_key(tc->td, result.block, &key);
1508                if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2, &cell_result)) {
1509                        cell_defer_no_holder_no_free(tc, &cell1);
1510                        return DM_MAPIO_SUBMITTED;
1511                }
1512
1513                inc_all_io_entry(tc->pool, bio);
1514                cell_defer_no_holder_no_free(tc, &cell2);
1515                cell_defer_no_holder_no_free(tc, &cell1);
1516
1517                remap(tc, bio, result.block);
1518                return DM_MAPIO_REMAPPED;
1519
1520        case -ENODATA:
1521                if (get_pool_mode(tc->pool) == PM_READ_ONLY) {
1522                        /*
1523                         * This block isn't provisioned, and we have no way
1524                         * of doing so.  Just error it.
1525                         */
1526                        bio_io_error(bio);
1527                        return DM_MAPIO_SUBMITTED;
1528                }
1529                /* fall through */
1530
1531        case -EWOULDBLOCK:
1532                /*
1533                 * In future, the failed dm_thin_find_block above could
1534                 * provide the hint to load the metadata into cache.
1535                 */
1536                thin_defer_bio(tc, bio);
1537                return DM_MAPIO_SUBMITTED;
1538
1539        default:
1540                /*
1541                 * Must always call bio_io_error on failure.
1542                 * dm_thin_find_block can fail with -EINVAL if the
1543                 * pool is switched to fail-io mode.
1544                 */
1545                bio_io_error(bio);
1546                return DM_MAPIO_SUBMITTED;
1547        }
1548}
1549
1550static int pool_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
1551{
1552        int r;
1553        unsigned long flags;
1554        struct pool_c *pt = container_of(cb, struct pool_c, callbacks);
1555
1556        spin_lock_irqsave(&pt->pool->lock, flags);
1557        r = !bio_list_empty(&pt->pool->retry_on_resume_list);
1558        spin_unlock_irqrestore(&pt->pool->lock, flags);
1559
1560        if (!r) {
1561                struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
1562                r = bdi_congested(&q->backing_dev_info, bdi_bits);
1563        }
1564
1565        return r;
1566}
1567
1568static void __requeue_bios(struct pool *pool)
1569{
1570        bio_list_merge(&pool->deferred_bios, &pool->retry_on_resume_list);
1571        bio_list_init(&pool->retry_on_resume_list);
1572}
1573
1574/*----------------------------------------------------------------
1575 * Binding of control targets to a pool object
1576 *--------------------------------------------------------------*/
1577static bool data_dev_supports_discard(struct pool_c *pt)
1578{
1579        struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
1580
1581        return q && blk_queue_discard(q);
1582}
1583
1584static bool is_factor(sector_t block_size, uint32_t n)
1585{
1586        return !sector_div(block_size, n);
1587}
1588
1589/*
1590 * If discard_passdown was enabled verify that the data device
1591 * supports discards.  Disable discard_passdown if not.
1592 */
1593static void disable_passdown_if_not_supported(struct pool_c *pt)
1594{
1595        struct pool *pool = pt->pool;
1596        struct block_device *data_bdev = pt->data_dev->bdev;
1597        struct queue_limits *data_limits = &bdev_get_queue(data_bdev)->limits;
1598        sector_t block_size = pool->sectors_per_block << SECTOR_SHIFT;
1599        const char *reason = NULL;
1600        char buf[BDEVNAME_SIZE];
1601
1602        if (!pt->adjusted_pf.discard_passdown)
1603                return;
1604
1605        if (!data_dev_supports_discard(pt))
1606                reason = "discard unsupported";
1607
1608        else if (data_limits->max_discard_sectors < pool->sectors_per_block)
1609                reason = "max discard sectors smaller than a block";
1610
1611        else if (data_limits->discard_granularity > block_size)
1612                reason = "discard granularity larger than a block";
1613
1614        else if (!is_factor(block_size, data_limits->discard_granularity))
1615                reason = "discard granularity not a factor of block size";
1616
1617        if (reason) {
1618                DMWARN("Data device (%s) %s: Disabling discard passdown.", bdevname(data_bdev, buf), reason);
1619                pt->adjusted_pf.discard_passdown = false;
1620        }
1621}
1622
1623static int bind_control_target(struct pool *pool, struct dm_target *ti)
1624{
1625        struct pool_c *pt = ti->private;
1626
1627        /*
1628         * We want to make sure that degraded pools are never upgraded.
1629         */
1630        enum pool_mode old_mode = pool->pf.mode;
1631        enum pool_mode new_mode = pt->adjusted_pf.mode;
1632
1633        if (old_mode > new_mode)
1634                new_mode = old_mode;
1635
1636        pool->ti = ti;
1637        pool->low_water_blocks = pt->low_water_blocks;
1638        pool->pf = pt->adjusted_pf;
1639
1640        set_pool_mode(pool, new_mode);
1641
1642        return 0;
1643}
1644
1645static void unbind_control_target(struct pool *pool, struct dm_target *ti)
1646{
1647        if (pool->ti == ti)
1648                pool->ti = NULL;
1649}
1650
1651/*----------------------------------------------------------------
1652 * Pool creation
1653 *--------------------------------------------------------------*/
1654/* Initialize pool features. */
1655static void pool_features_init(struct pool_features *pf)
1656{
1657        pf->mode = PM_WRITE;
1658        pf->zero_new_blocks = true;
1659        pf->discard_enabled = true;
1660        pf->discard_passdown = true;
1661}
1662
1663static void __pool_destroy(struct pool *pool)
1664{
1665        __pool_table_remove(pool);
1666
1667        if (dm_pool_metadata_close(pool->pmd) < 0)
1668                DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
1669
1670        dm_bio_prison_destroy(pool->prison);
1671        dm_kcopyd_client_destroy(pool->copier);
1672
1673        if (pool->wq)
1674                destroy_workqueue(pool->wq);
1675
1676        if (pool->next_mapping)
1677                mempool_free(pool->next_mapping, pool->mapping_pool);
1678        mempool_destroy(pool->mapping_pool);
1679        dm_deferred_set_destroy(pool->shared_read_ds);
1680        dm_deferred_set_destroy(pool->all_io_ds);
1681        kfree(pool);
1682}
1683
1684static struct kmem_cache *_new_mapping_cache;
1685
1686static struct pool *pool_create(struct mapped_device *pool_md,
1687                                struct block_device *metadata_dev,
1688                                unsigned long block_size,
1689                                int read_only, char **error)
1690{
1691        int r;
1692        void *err_p;
1693        struct pool *pool;
1694        struct dm_pool_metadata *pmd;
1695        bool format_device = read_only ? false : true;
1696
1697        pmd = dm_pool_metadata_open(metadata_dev, block_size, format_device);
1698        if (IS_ERR(pmd)) {
1699                *error = "Error creating metadata object";
1700                return (struct pool *)pmd;
1701        }
1702
1703        pool = kmalloc(sizeof(*pool), GFP_KERNEL);
1704        if (!pool) {
1705                *error = "Error allocating memory for pool";
1706                err_p = ERR_PTR(-ENOMEM);
1707                goto bad_pool;
1708        }
1709
1710        pool->pmd = pmd;
1711        pool->sectors_per_block = block_size;
1712        if (block_size & (block_size - 1))
1713                pool->sectors_per_block_shift = -1;
1714        else
1715                pool->sectors_per_block_shift = __ffs(block_size);
1716        pool->low_water_blocks = 0;
1717        pool_features_init(&pool->pf);
1718        pool->prison = dm_bio_prison_create(PRISON_CELLS);
1719        if (!pool->prison) {
1720                *error = "Error creating pool's bio prison";
1721                err_p = ERR_PTR(-ENOMEM);
1722                goto bad_prison;
1723        }
1724
1725        pool->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
1726        if (IS_ERR(pool->copier)) {
1727                r = PTR_ERR(pool->copier);
1728                *error = "Error creating pool's kcopyd client";
1729                err_p = ERR_PTR(r);
1730                goto bad_kcopyd_client;
1731        }
1732
1733        /*
1734         * Create singlethreaded workqueue that will service all devices
1735         * that use this metadata.
1736         */
1737        pool->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
1738        if (!pool->wq) {
1739                *error = "Error creating pool's workqueue";
1740                err_p = ERR_PTR(-ENOMEM);
1741                goto bad_wq;
1742        }
1743
1744        INIT_WORK(&pool->worker, do_worker);
1745        INIT_DELAYED_WORK(&pool->waker, do_waker);
1746        spin_lock_init(&pool->lock);
1747        bio_list_init(&pool->deferred_bios);
1748        bio_list_init(&pool->deferred_flush_bios);
1749        INIT_LIST_HEAD(&pool->prepared_mappings);
1750        INIT_LIST_HEAD(&pool->prepared_discards);
1751        pool->low_water_triggered = 0;
1752        pool->no_free_space = 0;
1753        bio_list_init(&pool->retry_on_resume_list);
1754
1755        pool->shared_read_ds = dm_deferred_set_create();
1756        if (!pool->shared_read_ds) {
1757                *error = "Error creating pool's shared read deferred set";
1758                err_p = ERR_PTR(-ENOMEM);
1759                goto bad_shared_read_ds;
1760        }
1761
1762        pool->all_io_ds = dm_deferred_set_create();
1763        if (!pool->all_io_ds) {
1764                *error = "Error creating pool's all io deferred set";
1765                err_p = ERR_PTR(-ENOMEM);
1766                goto bad_all_io_ds;
1767        }
1768
1769        pool->next_mapping = NULL;
1770        pool->mapping_pool = mempool_create_slab_pool(MAPPING_POOL_SIZE,
1771                                                      _new_mapping_cache);
1772        if (!pool->mapping_pool) {
1773                *error = "Error creating pool's mapping mempool";
1774                err_p = ERR_PTR(-ENOMEM);
1775                goto bad_mapping_pool;
1776        }
1777
1778        pool->ref_count = 1;
1779        pool->last_commit_jiffies = jiffies;
1780        pool->pool_md = pool_md;
1781        pool->md_dev = metadata_dev;
1782        __pool_table_insert(pool);
1783
1784        return pool;
1785
1786bad_mapping_pool:
1787        dm_deferred_set_destroy(pool->all_io_ds);
1788bad_all_io_ds:
1789        dm_deferred_set_destroy(pool->shared_read_ds);
1790bad_shared_read_ds:
1791        destroy_workqueue(pool->wq);
1792bad_wq:
1793        dm_kcopyd_client_destroy(pool->copier);
1794bad_kcopyd_client:
1795        dm_bio_prison_destroy(pool->prison);
1796bad_prison:
1797        kfree(pool);
1798bad_pool:
1799        if (dm_pool_metadata_close(pmd))
1800                DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
1801
1802        return err_p;
1803}
1804
1805static void __pool_inc(struct pool *pool)
1806{
1807        BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
1808        pool->ref_count++;
1809}
1810
1811static void __pool_dec(struct pool *pool)
1812{
1813        BUG_ON(!mutex_is_locked(&dm_thin_pool_table.mutex));
1814        BUG_ON(!pool->ref_count);
1815        if (!--pool->ref_count)
1816                __pool_destroy(pool);
1817}
1818
1819static struct pool *__pool_find(struct mapped_device *pool_md,
1820                                struct block_device *metadata_dev,
1821                                unsigned long block_size, int read_only,
1822                                char **error, int *created)
1823{
1824        struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev);
1825
1826        if (pool) {
1827                if (pool->pool_md != pool_md) {
1828                        *error = "metadata device already in use by a pool";
1829                        return ERR_PTR(-EBUSY);
1830                }
1831                __pool_inc(pool);
1832
1833        } else {
1834                pool = __pool_table_lookup(pool_md);
1835                if (pool) {
1836                        if (pool->md_dev != metadata_dev) {
1837                                *error = "different pool cannot replace a pool";
1838                                return ERR_PTR(-EINVAL);
1839                        }
1840                        __pool_inc(pool);
1841
1842                } else {
1843                        pool = pool_create(pool_md, metadata_dev, block_size, read_only, error);
1844                        *created = 1;
1845                }
1846        }
1847
1848        return pool;
1849}
1850
1851/*----------------------------------------------------------------
1852 * Pool target methods
1853 *--------------------------------------------------------------*/
1854static void pool_dtr(struct dm_target *ti)
1855{
1856        struct pool_c *pt = ti->private;
1857
1858        mutex_lock(&dm_thin_pool_table.mutex);
1859
1860        unbind_control_target(pt->pool, ti);
1861        __pool_dec(pt->pool);
1862        dm_put_device(ti, pt->metadata_dev);
1863        dm_put_device(ti, pt->data_dev);
1864        kfree(pt);
1865
1866        mutex_unlock(&dm_thin_pool_table.mutex);
1867}
1868
1869static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
1870                               struct dm_target *ti)
1871{
1872        int r;
1873        unsigned argc;
1874        const char *arg_name;
1875
1876        static struct dm_arg _args[] = {
1877                {0, 3, "Invalid number of pool feature arguments"},
1878        };
1879
1880        /*
1881         * No feature arguments supplied.
1882         */
1883        if (!as->argc)
1884                return 0;
1885
1886        r = dm_read_arg_group(_args, as, &argc, &ti->error);
1887        if (r)
1888                return -EINVAL;
1889
1890        while (argc && !r) {
1891                arg_name = dm_shift_arg(as);
1892                argc--;
1893
1894                if (!strcasecmp(arg_name, "skip_block_zeroing"))
1895                        pf->zero_new_blocks = false;
1896
1897                else if (!strcasecmp(arg_name, "ignore_discard"))
1898                        pf->discard_enabled = false;
1899
1900                else if (!strcasecmp(arg_name, "no_discard_passdown"))
1901                        pf->discard_passdown = false;
1902
1903                else if (!strcasecmp(arg_name, "read_only"))
1904                        pf->mode = PM_READ_ONLY;
1905
1906                else {
1907                        ti->error = "Unrecognised pool feature requested";
1908                        r = -EINVAL;
1909                        break;
1910                }
1911        }
1912
1913        return r;
1914}
1915
1916static void metadata_low_callback(void *context)
1917{
1918        struct pool *pool = context;
1919
1920        DMWARN("%s: reached low water mark for metadata device: sending event.",
1921               dm_device_name(pool->pool_md));
1922
1923        dm_table_event(pool->ti->table);
1924}
1925
1926static sector_t get_metadata_dev_size(struct block_device *bdev)
1927{
1928        sector_t metadata_dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
1929        char buffer[BDEVNAME_SIZE];
1930
1931        if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING) {
1932                DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
1933                       bdevname(bdev, buffer), THIN_METADATA_MAX_SECTORS);
1934                metadata_dev_size = THIN_METADATA_MAX_SECTORS_WARNING;
1935        }
1936
1937        return metadata_dev_size;
1938}
1939
1940static dm_block_t get_metadata_dev_size_in_blocks(struct block_device *bdev)
1941{
1942        sector_t metadata_dev_size = get_metadata_dev_size(bdev);
1943
1944        sector_div(metadata_dev_size, THIN_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
1945
1946        return metadata_dev_size;
1947}
1948
1949/*
1950 * When a metadata threshold is crossed a dm event is triggered, and
1951 * userland should respond by growing the metadata device.  We could let
1952 * userland set the threshold, like we do with the data threshold, but I'm
1953 * not sure they know enough to do this well.
1954 */
1955static dm_block_t calc_metadata_threshold(struct pool_c *pt)
1956{
1957        /*
1958         * 4M is ample for all ops with the possible exception of thin
1959         * device deletion which is harmless if it fails (just retry the
1960         * delete after you've grown the device).
1961         */
1962        dm_block_t quarter = get_metadata_dev_size_in_blocks(pt->metadata_dev->bdev) / 4;
1963        return min((dm_block_t)1024ULL /* 4M */, quarter);
1964}
1965
1966/*
1967 * thin-pool <metadata dev> <data dev>
1968 *           <data block size (sectors)>
1969 *           <low water mark (blocks)>
1970 *           [<#feature args> [<arg>]*]
1971 *
1972 * Optional feature arguments are:
1973 *           skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
1974 *           ignore_discard: disable discard
1975 *           no_discard_passdown: don't pass discards down to the data device
1976 */
1977static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
1978{
1979        int r, pool_created = 0;
1980        struct pool_c *pt;
1981        struct pool *pool;
1982        struct pool_features pf;
1983        struct dm_arg_set as;
1984        struct dm_dev *data_dev;
1985        unsigned long block_size;
1986        dm_block_t low_water_blocks;
1987        struct dm_dev *metadata_dev;
1988        fmode_t metadata_mode;
1989
1990        /*
1991         * FIXME Remove validation from scope of lock.
1992         */
1993        mutex_lock(&dm_thin_pool_table.mutex);
1994
1995        if (argc < 4) {
1996                ti->error = "Invalid argument count";
1997                r = -EINVAL;
1998                goto out_unlock;
1999        }
2000
2001        as.argc = argc;
2002        as.argv = argv;
2003
2004        /*
2005         * Set default pool features.
2006         */
2007        pool_features_init(&pf);
2008
2009        dm_consume_args(&as, 4);
2010        r = parse_pool_features(&as, &pf, ti);
2011        if (r)
2012                goto out_unlock;
2013
2014        metadata_mode = FMODE_READ | ((pf.mode == PM_READ_ONLY) ? 0 : FMODE_WRITE);
2015        r = dm_get_device(ti, argv[0], metadata_mode, &metadata_dev);
2016        if (r) {
2017                ti->error = "Error opening metadata block device";
2018                goto out_unlock;
2019        }
2020
2021        /*
2022         * Run for the side-effect of possibly issuing a warning if the
2023         * device is too big.
2024         */
2025        (void) get_metadata_dev_size(metadata_dev->bdev);
2026
2027        r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev);
2028        if (r) {
2029                ti->error = "Error getting data device";
2030                goto out_metadata;
2031        }
2032
2033        if (kstrtoul(argv[2], 10, &block_size) || !block_size ||
2034            block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
2035            block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
2036            block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
2037                ti->error = "Invalid block size";
2038                r = -EINVAL;
2039                goto out;
2040        }
2041
2042        if (kstrtoull(argv[3], 10, (unsigned long long *)&low_water_blocks)) {
2043                ti->error = "Invalid low water mark";
2044                r = -EINVAL;
2045                goto out;
2046        }
2047
2048        pt = kzalloc(sizeof(*pt), GFP_KERNEL);
2049        if (!pt) {
2050                r = -ENOMEM;
2051                goto out;
2052        }
2053
2054        pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,
2055                           block_size, pf.mode == PM_READ_ONLY, &ti->error, &pool_created);
2056        if (IS_ERR(pool)) {
2057                r = PTR_ERR(pool);
2058                goto out_free_pt;
2059        }
2060
2061        /*
2062         * 'pool_created' reflects whether this is the first table load.
2063         * Top level discard support is not allowed to be changed after
2064         * initial load.  This would require a pool reload to trigger thin
2065         * device changes.
2066         */
2067        if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
2068                ti->error = "Discard support cannot be disabled once enabled";
2069                r = -EINVAL;
2070                goto out_flags_changed;
2071        }
2072
2073        pt->pool = pool;
2074        pt->ti = ti;
2075        pt->metadata_dev = metadata_dev;
2076        pt->data_dev = data_dev;
2077        pt->low_water_blocks = low_water_blocks;
2078        pt->adjusted_pf = pt->requested_pf = pf;
2079        ti->num_flush_bios = 1;
2080
2081        /*
2082         * Only need to enable discards if the pool should pass
2083         * them down to the data device.  The thin device's discard
2084         * processing will cause mappings to be removed from the btree.
2085         */
2086        if (pf.discard_enabled && pf.discard_passdown) {
2087                ti->num_discard_bios = 1;
2088
2089                /*
2090                 * Setting 'discards_supported' circumvents the normal
2091                 * stacking of discard limits (this keeps the pool and
2092                 * thin devices' discard limits consistent).
2093                 */
2094                ti->discards_supported = true;
2095                ti->discard_zeroes_data_unsupported = true;
2096        }
2097        ti->private = pt;
2098
2099        r = dm_pool_register_metadata_threshold(pt->pool->pmd,
2100                                                calc_metadata_threshold(pt),
2101                                                metadata_low_callback,
2102                                                pool);
2103        if (r)
2104                goto out_free_pt;
2105
2106        pt->callbacks.congested_fn = pool_is_congested;
2107        dm_table_add_target_callbacks(ti->table, &pt->callbacks);
2108
2109        mutex_unlock(&dm_thin_pool_table.mutex);
2110
2111        return 0;
2112
2113out_flags_changed:
2114        __pool_dec(pool);
2115out_free_pt:
2116        kfree(pt);
2117out:
2118        dm_put_device(ti, data_dev);
2119out_metadata:
2120        dm_put_device(ti, metadata_dev);
2121out_unlock:
2122        mutex_unlock(&dm_thin_pool_table.mutex);
2123
2124        return r;
2125}
2126
2127static int pool_map(struct dm_target *ti, struct bio *bio)
2128{
2129        int r;
2130        struct pool_c *pt = ti->private;
2131        struct pool *pool = pt->pool;
2132        unsigned long flags;
2133
2134        /*
2135         * As this is a singleton target, ti->begin is always zero.
2136         */
2137        spin_lock_irqsave(&pool->lock, flags);
2138        bio->bi_bdev = pt->data_dev->bdev;
2139        r = DM_MAPIO_REMAPPED;
2140        spin_unlock_irqrestore(&pool->lock, flags);
2141
2142        return r;
2143}
2144
2145static int maybe_resize_data_dev(struct dm_target *ti, bool *need_commit)
2146{
2147        int r;
2148        struct pool_c *pt = ti->private;
2149        struct pool *pool = pt->pool;
2150        sector_t data_size = ti->len;
2151        dm_block_t sb_data_size;
2152
2153        *need_commit = false;
2154
2155        (void) sector_div(data_size, pool->sectors_per_block);
2156
2157        r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size);
2158        if (r) {
2159                DMERR("failed to retrieve data device size");
2160                return r;
2161        }
2162
2163        if (data_size < sb_data_size) {
2164                DMERR("pool target (%llu blocks) too small: expected %llu",
2165                      (unsigned long long)data_size, sb_data_size);
2166                return -EINVAL;
2167
2168        } else if (data_size > sb_data_size) {
2169                r = dm_pool_resize_data_dev(pool->pmd, data_size);
2170                if (r) {
2171                        DMERR("failed to resize data device");
2172                        set_pool_mode(pool, PM_READ_ONLY);
2173                        return r;
2174                }
2175
2176                *need_commit = true;
2177        }
2178
2179        return 0;
2180}
2181
2182static int maybe_resize_metadata_dev(struct dm_target *ti, bool *need_commit)
2183{
2184        int r;
2185        struct pool_c *pt = ti->private;
2186        struct pool *pool = pt->pool;
2187        dm_block_t metadata_dev_size, sb_metadata_dev_size;
2188
2189        *need_commit = false;
2190
2191        metadata_dev_size = get_metadata_dev_size_in_blocks(pool->md_dev);
2192
2193        r = dm_pool_get_metadata_dev_size(pool->pmd, &sb_metadata_dev_size);
2194        if (r) {
2195                DMERR("failed to retrieve data device size");
2196                return r;
2197        }
2198
2199        if (metadata_dev_size < sb_metadata_dev_size) {
2200                DMERR("metadata device (%llu blocks) too small: expected %llu",
2201                      metadata_dev_size, sb_metadata_dev_size);
2202                return -EINVAL;
2203
2204        } else if (metadata_dev_size > sb_metadata_dev_size) {
2205                r = dm_pool_resize_metadata_dev(pool->pmd, metadata_dev_size);
2206                if (r) {
2207                        DMERR("failed to resize metadata device");
2208                        return r;
2209                }
2210
2211                *need_commit = true;
2212        }
2213
2214        return 0;
2215}
2216
2217/*
2218 * Retrieves the number of blocks of the data device from
2219 * the superblock and compares it to the actual device size,
2220 * thus resizing the data device in case it has grown.
2221 *
2222 * This both copes with opening preallocated data devices in the ctr
2223 * being followed by a resume
2224 * -and-
2225 * calling the resume method individually after userspace has
2226 * grown the data device in reaction to a table event.
2227 */
2228static int pool_preresume(struct dm_target *ti)
2229{
2230        int r;
2231        bool need_commit1, need_commit2;
2232        struct pool_c *pt = ti->private;
2233        struct pool *pool = pt->pool;
2234
2235        /*
2236         * Take control of the pool object.
2237         */
2238        r = bind_control_target(pool, ti);
2239        if (r)
2240                return r;
2241
2242        r = maybe_resize_data_dev(ti, &need_commit1);
2243        if (r)
2244                return r;
2245
2246        r = maybe_resize_metadata_dev(ti, &need_commit2);
2247        if (r)
2248                return r;
2249
2250        if (need_commit1 || need_commit2)
2251                (void) commit_or_fallback(pool);
2252
2253        return 0;
2254}
2255
2256static void pool_resume(struct dm_target *ti)
2257{
2258        struct pool_c *pt = ti->private;
2259        struct pool *pool = pt->pool;
2260        unsigned long flags;
2261
2262        spin_lock_irqsave(&pool->lock, flags);
2263        pool->low_water_triggered = 0;
2264        pool->no_free_space = 0;
2265        __requeue_bios(pool);
2266        spin_unlock_irqrestore(&pool->lock, flags);
2267
2268        do_waker(&pool->waker.work);
2269}
2270
2271static void pool_postsuspend(struct dm_target *ti)
2272{
2273        struct pool_c *pt = ti->private;
2274        struct pool *pool = pt->pool;
2275
2276        cancel_delayed_work(&pool->waker);
2277        flush_workqueue(pool->wq);
2278        (void) commit_or_fallback(pool);
2279}
2280
2281static int check_arg_count(unsigned argc, unsigned args_required)
2282{
2283        if (argc != args_required) {
2284                DMWARN("Message received with %u arguments instead of %u.",
2285                       argc, args_required);
2286                return -EINVAL;
2287        }
2288
2289        return 0;
2290}
2291
2292static int read_dev_id(char *arg, dm_thin_id *dev_id, int warning)
2293{
2294        if (!kstrtoull(arg, 10, (unsigned long long *)dev_id) &&
2295            *dev_id <= MAX_DEV_ID)
2296                return 0;
2297
2298        if (warning)
2299                DMWARN("Message received with invalid device id: %s", arg);
2300
2301        return -EINVAL;
2302}
2303
2304static int process_create_thin_mesg(unsigned argc, char **argv, struct pool *pool)
2305{
2306        dm_thin_id dev_id;
2307        int r;
2308
2309        r = check_arg_count(argc, 2);
2310        if (r)
2311                return r;
2312
2313        r = read_dev_id(argv[1], &dev_id, 1);
2314        if (r)
2315                return r;
2316
2317        r = dm_pool_create_thin(pool->pmd, dev_id);
2318        if (r) {
2319                DMWARN("Creation of new thinly-provisioned device with id %s failed.",
2320                       argv[1]);
2321                return r;
2322        }
2323
2324        return 0;
2325}
2326
2327static int process_create_snap_mesg(unsigned argc, char **argv, struct pool *pool)
2328{
2329        dm_thin_id dev_id;
2330        dm_thin_id origin_dev_id;
2331        int r;
2332
2333        r = check_arg_count(argc, 3);
2334        if (r)
2335                return r;
2336
2337        r = read_dev_id(argv[1], &dev_id, 1);
2338        if (r)
2339                return r;
2340
2341        r = read_dev_id(argv[2], &origin_dev_id, 1);
2342        if (r)
2343                return r;
2344
2345        r = dm_pool_create_snap(pool->pmd, dev_id, origin_dev_id);
2346        if (r) {
2347                DMWARN("Creation of new snapshot %s of device %s failed.",
2348                       argv[1], argv[2]);
2349                return r;
2350        }
2351
2352        return 0;
2353}
2354
2355static int process_delete_mesg(unsigned argc, char **argv, struct pool *pool)
2356{
2357        dm_thin_id dev_id;
2358        int r;
2359
2360        r = check_arg_count(argc, 2);
2361        if (r)
2362                return r;
2363
2364        r = read_dev_id(argv[1], &dev_id, 1);
2365        if (r)
2366                return r;
2367
2368        r = dm_pool_delete_thin_device(pool->pmd, dev_id);
2369        if (r)
2370                DMWARN("Deletion of thin device %s failed.", argv[1]);
2371
2372        return r;
2373}
2374
2375static int process_set_transaction_id_mesg(unsigned argc, char **argv, struct pool *pool)
2376{
2377        dm_thin_id old_id, new_id;
2378        int r;
2379
2380        r = check_arg_count(argc, 3);
2381        if (r)
2382                return r;
2383
2384        if (kstrtoull(argv[1], 10, (unsigned long long *)&old_id)) {
2385                DMWARN("set_transaction_id message: Unrecognised id %s.", argv[1]);
2386                return -EINVAL;
2387        }
2388
2389        if (kstrtoull(argv[2], 10, (unsigned long long *)&new_id)) {
2390                DMWARN("set_transaction_id message: Unrecognised new id %s.", argv[2]);
2391                return -EINVAL;
2392        }
2393
2394        r = dm_pool_set_metadata_transaction_id(pool->pmd, old_id, new_id);
2395        if (r) {
2396                DMWARN("Failed to change transaction id from %s to %s.",
2397                       argv[1], argv[2]);
2398                return r;
2399        }
2400
2401        return 0;
2402}
2403
2404static int process_reserve_metadata_snap_mesg(unsigned argc, char **argv, struct pool *pool)
2405{
2406        int r;
2407
2408        r = check_arg_count(argc, 1);
2409        if (r)
2410                return r;
2411
2412        (void) commit_or_fallback(pool);
2413
2414        r = dm_pool_reserve_metadata_snap(pool->pmd);
2415        if (r)
2416                DMWARN("reserve_metadata_snap message failed.");
2417
2418        return r;
2419}
2420
2421static int process_release_metadata_snap_mesg(unsigned argc, char **argv, struct pool *pool)
2422{
2423        int r;
2424
2425        r = check_arg_count(argc, 1);
2426        if (r)
2427                return r;
2428
2429        r = dm_pool_release_metadata_snap(pool->pmd);
2430        if (r)
2431                DMWARN("release_metadata_snap message failed.");
2432
2433        return r;
2434}
2435
2436/*
2437 * Messages supported:
2438 *   create_thin        <dev_id>
2439 *   create_snap        <dev_id> <origin_id>
2440 *   delete             <dev_id>
2441 *   trim               <dev_id> <new_size_in_sectors>
2442 *   set_transaction_id <current_trans_id> <new_trans_id>
2443 *   reserve_metadata_snap
2444 *   release_metadata_snap
2445 */
2446static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
2447{
2448        int r = -EINVAL;
2449        struct pool_c *pt = ti->private;
2450        struct pool *pool = pt->pool;
2451
2452        if (!strcasecmp(argv[0], "create_thin"))
2453                r = process_create_thin_mesg(argc, argv, pool);
2454
2455        else if (!strcasecmp(argv[0], "create_snap"))
2456                r = process_create_snap_mesg(argc, argv, pool);
2457
2458        else if (!strcasecmp(argv[0], "delete"))
2459                r = process_delete_mesg(argc, argv, pool);
2460
2461        else if (!strcasecmp(argv[0], "set_transaction_id"))
2462                r = process_set_transaction_id_mesg(argc, argv, pool);
2463
2464        else if (!strcasecmp(argv[0], "reserve_metadata_snap"))
2465                r = process_reserve_metadata_snap_mesg(argc, argv, pool);
2466
2467        else if (!strcasecmp(argv[0], "release_metadata_snap"))
2468                r = process_release_metadata_snap_mesg(argc, argv, pool);
2469
2470        else
2471                DMWARN("Unrecognised thin pool target message received: %s", argv[0]);
2472
2473        if (!r)
2474                (void) commit_or_fallback(pool);
2475
2476        return r;
2477}
2478
2479static void emit_flags(struct pool_features *pf, char *result,
2480                       unsigned sz, unsigned maxlen)
2481{
2482        unsigned count = !pf->zero_new_blocks + !pf->discard_enabled +
2483                !pf->discard_passdown + (pf->mode == PM_READ_ONLY);
2484        DMEMIT("%u ", count);
2485
2486        if (!pf->zero_new_blocks)
2487                DMEMIT("skip_block_zeroing ");
2488
2489        if (!pf->discard_enabled)
2490                DMEMIT("ignore_discard ");
2491
2492        if (!pf->discard_passdown)
2493                DMEMIT("no_discard_passdown ");
2494
2495        if (pf->mode == PM_READ_ONLY)
2496                DMEMIT("read_only ");
2497}
2498
2499/*
2500 * Status line is:
2501 *    <transaction id> <used metadata sectors>/<total metadata sectors>
2502 *    <used data sectors>/<total data sectors> <held metadata root>
2503 */
2504static void pool_status(struct dm_target *ti, status_type_t type,
2505                        unsigned status_flags, char *result, unsigned maxlen)
2506{
2507        int r;
2508        unsigned sz = 0;
2509        uint64_t transaction_id;
2510        dm_block_t nr_free_blocks_data;
2511        dm_block_t nr_free_blocks_metadata;
2512        dm_block_t nr_blocks_data;
2513        dm_block_t nr_blocks_metadata;
2514        dm_block_t held_root;
2515        char buf[BDEVNAME_SIZE];
2516        char buf2[BDEVNAME_SIZE];
2517        struct pool_c *pt = ti->private;
2518        struct pool *pool = pt->pool;
2519
2520        switch (type) {
2521        case STATUSTYPE_INFO:
2522                if (get_pool_mode(pool) == PM_FAIL) {
2523                        DMEMIT("Fail");
2524                        break;
2525                }
2526
2527                /* Commit to ensure statistics aren't out-of-date */
2528                if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
2529                        (void) commit_or_fallback(pool);
2530
2531                r = dm_pool_get_metadata_transaction_id(pool->pmd, &transaction_id);
2532                if (r) {
2533                        DMERR("dm_pool_get_metadata_transaction_id returned %d", r);
2534                        goto err;
2535                }
2536
2537                r = dm_pool_get_free_metadata_block_count(pool->pmd, &nr_free_blocks_metadata);
2538                if (r) {
2539                        DMERR("dm_pool_get_free_metadata_block_count returned %d", r);
2540                        goto err;
2541                }
2542
2543                r = dm_pool_get_metadata_dev_size(pool->pmd, &nr_blocks_metadata);
2544                if (r) {
2545                        DMERR("dm_pool_get_metadata_dev_size returned %d", r);
2546                        goto err;
2547                }
2548
2549                r = dm_pool_get_free_block_count(pool->pmd, &nr_free_blocks_data);
2550                if (r) {
2551                        DMERR("dm_pool_get_free_block_count returned %d", r);
2552                        goto err;
2553                }
2554
2555                r = dm_pool_get_data_dev_size(pool->pmd, &nr_blocks_data);
2556                if (r) {
2557                        DMERR("dm_pool_get_data_dev_size returned %d", r);
2558                        goto err;
2559                }
2560
2561                r = dm_pool_get_metadata_snap(pool->pmd, &held_root);
2562                if (r) {
2563                        DMERR("dm_pool_get_metadata_snap returned %d", r);
2564                        goto err;
2565                }
2566
2567                DMEMIT("%llu %llu/%llu %llu/%llu ",
2568                       (unsigned long long)transaction_id,
2569                       (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
2570                       (unsigned long long)nr_blocks_metadata,
2571                       (unsigned long long)(nr_blocks_data - nr_free_blocks_data),
2572                       (unsigned long long)nr_blocks_data);
2573
2574                if (held_root)
2575                        DMEMIT("%llu ", held_root);
2576                else
2577                        DMEMIT("- ");
2578
2579                if (pool->pf.mode == PM_READ_ONLY)
2580                        DMEMIT("ro ");
2581                else
2582                        DMEMIT("rw ");
2583
2584                if (!pool->pf.discard_enabled)
2585                        DMEMIT("ignore_discard");
2586                else if (pool->pf.discard_passdown)
2587                        DMEMIT("discard_passdown");
2588                else
2589                        DMEMIT("no_discard_passdown");
2590
2591                break;
2592
2593        case STATUSTYPE_TABLE:
2594                DMEMIT("%s %s %lu %llu ",
2595                       format_dev_t(buf, pt->metadata_dev->bdev->bd_dev),
2596                       format_dev_t(buf2, pt->data_dev->bdev->bd_dev),
2597                       (unsigned long)pool->sectors_per_block,
2598                       (unsigned long long)pt->low_water_blocks);
2599                emit_flags(&pt->requested_pf, result, sz, maxlen);
2600                break;
2601        }
2602        return;
2603
2604err:
2605        DMEMIT("Error");
2606}
2607
2608static int pool_iterate_devices(struct dm_target *ti,
2609                                iterate_devices_callout_fn fn, void *data)
2610{
2611        struct pool_c *pt = ti->private;
2612
2613        return fn(ti, pt->data_dev, 0, ti->len, data);
2614}
2615
2616static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
2617                      struct bio_vec *biovec, int max_size)
2618{
2619        struct pool_c *pt = ti->private;
2620        struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
2621
2622        if (!q->merge_bvec_fn)
2623                return max_size;
2624
2625        bvm->bi_bdev = pt->data_dev->bdev;
2626
2627        return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
2628}
2629
2630static void set_discard_limits(struct pool_c *pt, struct queue_limits *limits)
2631{
2632        struct pool *pool = pt->pool;
2633        struct queue_limits *data_limits;
2634
2635        limits->max_discard_sectors = pool->sectors_per_block;
2636
2637        /*
2638         * discard_granularity is just a hint, and not enforced.
2639         */
2640        if (pt->adjusted_pf.discard_passdown) {
2641                data_limits = &bdev_get_queue(pt->data_dev->bdev)->limits;
2642                limits->discard_granularity = data_limits->discard_granularity;
2643        } else
2644                limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
2645}
2646
2647static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
2648{
2649        struct pool_c *pt = ti->private;
2650        struct pool *pool = pt->pool;
2651
2652        blk_limits_io_min(limits, 0);
2653        blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
2654
2655        /*
2656         * pt->adjusted_pf is a staging area for the actual features to use.
2657         * They get transferred to the live pool in bind_control_target()
2658         * called from pool_preresume().
2659         */
2660        if (!pt->adjusted_pf.discard_enabled)
2661                return;
2662
2663        disable_passdown_if_not_supported(pt);
2664
2665        set_discard_limits(pt, limits);
2666}
2667
2668static struct target_type pool_target = {
2669        .name = "thin-pool",
2670        .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
2671                    DM_TARGET_IMMUTABLE,
2672        .version = {1, 8, 0},
2673        .module = THIS_MODULE,
2674        .ctr = pool_ctr,
2675        .dtr = pool_dtr,
2676        .map = pool_map,
2677        .postsuspend = pool_postsuspend,
2678        .preresume = pool_preresume,
2679        .resume = pool_resume,
2680        .message = pool_message,
2681        .status = pool_status,
2682        .merge = pool_merge,
2683        .iterate_devices = pool_iterate_devices,
2684        .io_hints = pool_io_hints,
2685};
2686
2687/*----------------------------------------------------------------
2688 * Thin target methods
2689 *--------------------------------------------------------------*/
2690static void thin_dtr(struct dm_target *ti)
2691{
2692        struct thin_c *tc = ti->private;
2693
2694        mutex_lock(&dm_thin_pool_table.mutex);
2695
2696        __pool_dec(tc->pool);
2697        dm_pool_close_thin_device(tc->td);
2698        dm_put_device(ti, tc->pool_dev);
2699        if (tc->origin_dev)
2700                dm_put_device(ti, tc->origin_dev);
2701        kfree(tc);
2702
2703        mutex_unlock(&dm_thin_pool_table.mutex);
2704}
2705
2706/*
2707 * Thin target parameters:
2708 *
2709 * <pool_dev> <dev_id> [origin_dev]
2710 *
2711 * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
2712 * dev_id: the internal device identifier
2713 * origin_dev: a device external to the pool that should act as the origin
2714 *
2715 * If the pool device has discards disabled, they get disabled for the thin
2716 * device as well.
2717 */
2718static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
2719{
2720        int r;
2721        struct thin_c *tc;
2722        struct dm_dev *pool_dev, *origin_dev;
2723        struct mapped_device *pool_md;
2724
2725        mutex_lock(&dm_thin_pool_table.mutex);
2726
2727        if (argc != 2 && argc != 3) {
2728                ti->error = "Invalid argument count";
2729                r = -EINVAL;
2730                goto out_unlock;
2731        }
2732
2733        tc = ti->private = kzalloc(sizeof(*tc), GFP_KERNEL);
2734        if (!tc) {
2735                ti->error = "Out of memory";
2736                r = -ENOMEM;
2737                goto out_unlock;
2738        }
2739
2740        if (argc == 3) {
2741                r = dm_get_device(ti, argv[2], FMODE_READ, &origin_dev);
2742                if (r) {
2743                        ti->error = "Error opening origin device";
2744                        goto bad_origin_dev;
2745                }
2746                tc->origin_dev = origin_dev;
2747        }
2748
2749        r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &pool_dev);
2750        if (r) {
2751                ti->error = "Error opening pool device";
2752                goto bad_pool_dev;
2753        }
2754        tc->pool_dev = pool_dev;
2755
2756        if (read_dev_id(argv[1], (unsigned long long *)&tc->dev_id, 0)) {
2757                ti->error = "Invalid device id";
2758                r = -EINVAL;
2759                goto bad_common;
2760        }
2761
2762        pool_md = dm_get_md(tc->pool_dev->bdev->bd_dev);
2763        if (!pool_md) {
2764                ti->error = "Couldn't get pool mapped device";
2765                r = -EINVAL;
2766                goto bad_common;
2767        }
2768
2769        tc->pool = __pool_table_lookup(pool_md);
2770        if (!tc->pool) {
2771                ti->error = "Couldn't find pool object";
2772                r = -EINVAL;
2773                goto bad_pool_lookup;
2774        }
2775        __pool_inc(tc->pool);
2776
2777        if (get_pool_mode(tc->pool) == PM_FAIL) {
2778                ti->error = "Couldn't open thin device, Pool is in fail mode";
2779                goto bad_thin_open;
2780        }
2781
2782        r = dm_pool_open_thin_device(tc->pool->pmd, tc->dev_id, &tc->td);
2783        if (r) {
2784                ti->error = "Couldn't open thin internal device";
2785                goto bad_thin_open;
2786        }
2787
2788        r = dm_set_target_max_io_len(ti, tc->pool->sectors_per_block);
2789        if (r)
2790                goto bad_thin_open;
2791
2792        ti->num_flush_bios = 1;
2793        ti->flush_supported = true;
2794        ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook);
2795
2796        /* In case the pool supports discards, pass them on. */
2797        if (tc->pool->pf.discard_enabled) {
2798                ti->discards_supported = true;
2799                ti->num_discard_bios = 1;
2800                ti->discard_zeroes_data_unsupported = true;
2801                /* Discard bios must be split on a block boundary */
2802                ti->split_discard_bios = true;
2803        }
2804
2805        dm_put(pool_md);
2806
2807        mutex_unlock(&dm_thin_pool_table.mutex);
2808
2809        return 0;
2810
2811bad_thin_open:
2812        __pool_dec(tc->pool);
2813bad_pool_lookup:
2814        dm_put(pool_md);
2815bad_common:
2816        dm_put_device(ti, tc->pool_dev);
2817bad_pool_dev:
2818        if (tc->origin_dev)
2819                dm_put_device(ti, tc->origin_dev);
2820bad_origin_dev:
2821        kfree(tc);
2822out_unlock:
2823        mutex_unlock(&dm_thin_pool_table.mutex);
2824
2825        return r;
2826}
2827
2828static int thin_map(struct dm_target *ti, struct bio *bio)
2829{
2830        bio->bi_sector = dm_target_offset(ti, bio->bi_sector);
2831
2832        return thin_bio_map(ti, bio);
2833}
2834
2835static int thin_endio(struct dm_target *ti, struct bio *bio, int err)
2836{
2837        unsigned long flags;
2838        struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
2839        struct list_head work;
2840        struct dm_thin_new_mapping *m, *tmp;
2841        struct pool *pool = h->tc->pool;
2842
2843        if (h->shared_read_entry) {
2844                INIT_LIST_HEAD(&work);
2845                dm_deferred_entry_dec(h->shared_read_entry, &work);
2846
2847                spin_lock_irqsave(&pool->lock, flags);
2848                list_for_each_entry_safe(m, tmp, &work, list) {
2849                        list_del(&m->list);
2850                        m->quiesced = 1;
2851                        __maybe_add_mapping(m);
2852                }
2853                spin_unlock_irqrestore(&pool->lock, flags);
2854        }
2855
2856        if (h->all_io_entry) {
2857                INIT_LIST_HEAD(&work);
2858                dm_deferred_entry_dec(h->all_io_entry, &work);
2859                if (!list_empty(&work)) {
2860                        spin_lock_irqsave(&pool->lock, flags);
2861                        list_for_each_entry_safe(m, tmp, &work, list)
2862                                list_add(&m->list, &pool->prepared_discards);
2863                        spin_unlock_irqrestore(&pool->lock, flags);
2864                        wake_worker(pool);
2865                }
2866        }
2867
2868        return 0;
2869}
2870
2871static void thin_postsuspend(struct dm_target *ti)
2872{
2873        if (dm_noflush_suspending(ti))
2874                requeue_io((struct thin_c *)ti->private);
2875}
2876
2877/*
2878 * <nr mapped sectors> <highest mapped sector>
2879 */
2880static void thin_status(struct dm_target *ti, status_type_t type,
2881                        unsigned status_flags, char *result, unsigned maxlen)
2882{
2883        int r;
2884        ssize_t sz = 0;
2885        dm_block_t mapped, highest;
2886        char buf[BDEVNAME_SIZE];
2887        struct thin_c *tc = ti->private;
2888
2889        if (get_pool_mode(tc->pool) == PM_FAIL) {
2890                DMEMIT("Fail");
2891                return;
2892        }
2893
2894        if (!tc->td)
2895                DMEMIT("-");
2896        else {
2897                switch (type) {
2898                case STATUSTYPE_INFO:
2899                        r = dm_thin_get_mapped_count(tc->td, &mapped);
2900                        if (r) {
2901                                DMERR("dm_thin_get_mapped_count returned %d", r);
2902                                goto err;
2903                        }
2904
2905                        r = dm_thin_get_highest_mapped_block(tc->td, &highest);
2906                        if (r < 0) {
2907                                DMERR("dm_thin_get_highest_mapped_block returned %d", r);
2908                                goto err;
2909                        }
2910
2911                        DMEMIT("%llu ", mapped * tc->pool->sectors_per_block);
2912                        if (r)
2913                                DMEMIT("%llu", ((highest + 1) *
2914                                                tc->pool->sectors_per_block) - 1);
2915                        else
2916                                DMEMIT("-");
2917                        break;
2918
2919                case STATUSTYPE_TABLE:
2920                        DMEMIT("%s %lu",
2921                               format_dev_t(buf, tc->pool_dev->bdev->bd_dev),
2922                               (unsigned long) tc->dev_id);
2923                        if (tc->origin_dev)
2924                                DMEMIT(" %s", format_dev_t(buf, tc->origin_dev->bdev->bd_dev));
2925                        break;
2926                }
2927        }
2928
2929        return;
2930
2931err:
2932        DMEMIT("Error");
2933}
2934
2935static int thin_iterate_devices(struct dm_target *ti,
2936                                iterate_devices_callout_fn fn, void *data)
2937{
2938        sector_t blocks;
2939        struct thin_c *tc = ti->private;
2940        struct pool *pool = tc->pool;
2941
2942        /*
2943         * We can't call dm_pool_get_data_dev_size() since that blocks.  So
2944         * we follow a more convoluted path through to the pool's target.
2945         */
2946        if (!pool->ti)
2947                return 0;       /* nothing is bound */
2948
2949        blocks = pool->ti->len;
2950        (void) sector_div(blocks, pool->sectors_per_block);
2951        if (blocks)
2952                return fn(ti, tc->pool_dev, 0, pool->sectors_per_block * blocks, data);
2953
2954        return 0;
2955}
2956
2957static struct target_type thin_target = {
2958        .name = "thin",
2959        .version = {1, 8, 0},
2960        .module = THIS_MODULE,
2961        .ctr = thin_ctr,
2962        .dtr = thin_dtr,
2963        .map = thin_map,
2964        .end_io = thin_endio,
2965        .postsuspend = thin_postsuspend,
2966        .status = thin_status,
2967        .iterate_devices = thin_iterate_devices,
2968};
2969
2970/*----------------------------------------------------------------*/
2971
2972static int __init dm_thin_init(void)
2973{
2974        int r;
2975
2976        pool_table_init();
2977
2978        r = dm_register_target(&thin_target);
2979        if (r)
2980                return r;
2981
2982        r = dm_register_target(&pool_target);
2983        if (r)
2984                goto bad_pool_target;
2985
2986        r = -ENOMEM;
2987
2988        _new_mapping_cache = KMEM_CACHE(dm_thin_new_mapping, 0);
2989        if (!_new_mapping_cache)
2990                goto bad_new_mapping_cache;
2991
2992        return 0;
2993
2994bad_new_mapping_cache:
2995        dm_unregister_target(&pool_target);
2996bad_pool_target:
2997        dm_unregister_target(&thin_target);
2998
2999        return r;
3000}
3001
3002static void dm_thin_exit(void)
3003{
3004        dm_unregister_target(&thin_target);
3005        dm_unregister_target(&pool_target);
3006
3007        kmem_cache_destroy(_new_mapping_cache);
3008}
3009
3010module_init(dm_thin_init);
3011module_exit(dm_thin_exit);
3012
3013MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
3014MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
3015MODULE_LICENSE("GPL");
3016
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