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