linux/drivers/md/dm-raid1.c
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   1/*
   2 * Copyright (C) 2003 Sistina Software Limited.
   3 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
   4 *
   5 * This file is released under the GPL.
   6 */
   7
   8#include "dm-bio-record.h"
   9
  10#include <linux/init.h>
  11#include <linux/mempool.h>
  12#include <linux/module.h>
  13#include <linux/pagemap.h>
  14#include <linux/slab.h>
  15#include <linux/workqueue.h>
  16#include <linux/device-mapper.h>
  17#include <linux/dm-io.h>
  18#include <linux/dm-dirty-log.h>
  19#include <linux/dm-kcopyd.h>
  20#include <linux/dm-region-hash.h>
  21
  22#define DM_MSG_PREFIX "raid1"
  23
  24#define MAX_RECOVERY 1  /* Maximum number of regions recovered in parallel. */
  25
  26#define DM_RAID1_HANDLE_ERRORS 0x01
  27#define errors_handled(p)       ((p)->features & DM_RAID1_HANDLE_ERRORS)
  28
  29static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
  30
  31/*-----------------------------------------------------------------
  32 * Mirror set structures.
  33 *---------------------------------------------------------------*/
  34enum dm_raid1_error {
  35        DM_RAID1_WRITE_ERROR,
  36        DM_RAID1_FLUSH_ERROR,
  37        DM_RAID1_SYNC_ERROR,
  38        DM_RAID1_READ_ERROR
  39};
  40
  41struct mirror {
  42        struct mirror_set *ms;
  43        atomic_t error_count;
  44        unsigned long error_type;
  45        struct dm_dev *dev;
  46        sector_t offset;
  47};
  48
  49struct mirror_set {
  50        struct dm_target *ti;
  51        struct list_head list;
  52
  53        uint64_t features;
  54
  55        spinlock_t lock;        /* protects the lists */
  56        struct bio_list reads;
  57        struct bio_list writes;
  58        struct bio_list failures;
  59        struct bio_list holds;  /* bios are waiting until suspend */
  60
  61        struct dm_region_hash *rh;
  62        struct dm_kcopyd_client *kcopyd_client;
  63        struct dm_io_client *io_client;
  64        mempool_t *read_record_pool;
  65
  66        /* recovery */
  67        region_t nr_regions;
  68        int in_sync;
  69        int log_failure;
  70        int leg_failure;
  71        atomic_t suspend;
  72
  73        atomic_t default_mirror;        /* Default mirror */
  74
  75        struct workqueue_struct *kmirrord_wq;
  76        struct work_struct kmirrord_work;
  77        struct timer_list timer;
  78        unsigned long timer_pending;
  79
  80        struct work_struct trigger_event;
  81
  82        unsigned nr_mirrors;
  83        struct mirror mirror[0];
  84};
  85
  86static void wakeup_mirrord(void *context)
  87{
  88        struct mirror_set *ms = context;
  89
  90        queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
  91}
  92
  93static void delayed_wake_fn(unsigned long data)
  94{
  95        struct mirror_set *ms = (struct mirror_set *) data;
  96
  97        clear_bit(0, &ms->timer_pending);
  98        wakeup_mirrord(ms);
  99}
 100
 101static void delayed_wake(struct mirror_set *ms)
 102{
 103        if (test_and_set_bit(0, &ms->timer_pending))
 104                return;
 105
 106        ms->timer.expires = jiffies + HZ / 5;
 107        ms->timer.data = (unsigned long) ms;
 108        ms->timer.function = delayed_wake_fn;
 109        add_timer(&ms->timer);
 110}
 111
 112static void wakeup_all_recovery_waiters(void *context)
 113{
 114        wake_up_all(&_kmirrord_recovery_stopped);
 115}
 116
 117static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
 118{
 119        unsigned long flags;
 120        int should_wake = 0;
 121        struct bio_list *bl;
 122
 123        bl = (rw == WRITE) ? &ms->writes : &ms->reads;
 124        spin_lock_irqsave(&ms->lock, flags);
 125        should_wake = !(bl->head);
 126        bio_list_add(bl, bio);
 127        spin_unlock_irqrestore(&ms->lock, flags);
 128
 129        if (should_wake)
 130                wakeup_mirrord(ms);
 131}
 132
 133static void dispatch_bios(void *context, struct bio_list *bio_list)
 134{
 135        struct mirror_set *ms = context;
 136        struct bio *bio;
 137
 138        while ((bio = bio_list_pop(bio_list)))
 139                queue_bio(ms, bio, WRITE);
 140}
 141
 142#define MIN_READ_RECORDS 20
 143struct dm_raid1_read_record {
 144        struct mirror *m;
 145        struct dm_bio_details details;
 146};
 147
 148static struct kmem_cache *_dm_raid1_read_record_cache;
 149
 150/*
 151 * Every mirror should look like this one.
 152 */
 153#define DEFAULT_MIRROR 0
 154
 155/*
 156 * This is yucky.  We squirrel the mirror struct away inside
 157 * bi_next for read/write buffers.  This is safe since the bh
 158 * doesn't get submitted to the lower levels of block layer.
 159 */
 160static struct mirror *bio_get_m(struct bio *bio)
 161{
 162        return (struct mirror *) bio->bi_next;
 163}
 164
 165static void bio_set_m(struct bio *bio, struct mirror *m)
 166{
 167        bio->bi_next = (struct bio *) m;
 168}
 169
 170static struct mirror *get_default_mirror(struct mirror_set *ms)
 171{
 172        return &ms->mirror[atomic_read(&ms->default_mirror)];
 173}
 174
 175static void set_default_mirror(struct mirror *m)
 176{
 177        struct mirror_set *ms = m->ms;
 178        struct mirror *m0 = &(ms->mirror[0]);
 179
 180        atomic_set(&ms->default_mirror, m - m0);
 181}
 182
 183static struct mirror *get_valid_mirror(struct mirror_set *ms)
 184{
 185        struct mirror *m;
 186
 187        for (m = ms->mirror; m < ms->mirror + ms->nr_mirrors; m++)
 188                if (!atomic_read(&m->error_count))
 189                        return m;
 190
 191        return NULL;
 192}
 193
 194/* fail_mirror
 195 * @m: mirror device to fail
 196 * @error_type: one of the enum's, DM_RAID1_*_ERROR
 197 *
 198 * If errors are being handled, record the type of
 199 * error encountered for this device.  If this type
 200 * of error has already been recorded, we can return;
 201 * otherwise, we must signal userspace by triggering
 202 * an event.  Additionally, if the device is the
 203 * primary device, we must choose a new primary, but
 204 * only if the mirror is in-sync.
 205 *
 206 * This function must not block.
 207 */
 208static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
 209{
 210        struct mirror_set *ms = m->ms;
 211        struct mirror *new;
 212
 213        ms->leg_failure = 1;
 214
 215        /*
 216         * error_count is used for nothing more than a
 217         * simple way to tell if a device has encountered
 218         * errors.
 219         */
 220        atomic_inc(&m->error_count);
 221
 222        if (test_and_set_bit(error_type, &m->error_type))
 223                return;
 224
 225        if (!errors_handled(ms))
 226                return;
 227
 228        if (m != get_default_mirror(ms))
 229                goto out;
 230
 231        if (!ms->in_sync) {
 232                /*
 233                 * Better to issue requests to same failing device
 234                 * than to risk returning corrupt data.
 235                 */
 236                DMERR("Primary mirror (%s) failed while out-of-sync: "
 237                      "Reads may fail.", m->dev->name);
 238                goto out;
 239        }
 240
 241        new = get_valid_mirror(ms);
 242        if (new)
 243                set_default_mirror(new);
 244        else
 245                DMWARN("All sides of mirror have failed.");
 246
 247out:
 248        schedule_work(&ms->trigger_event);
 249}
 250
 251static int mirror_flush(struct dm_target *ti)
 252{
 253        struct mirror_set *ms = ti->private;
 254        unsigned long error_bits;
 255
 256        unsigned int i;
 257        struct dm_io_region io[ms->nr_mirrors];
 258        struct mirror *m;
 259        struct dm_io_request io_req = {
 260                .bi_rw = WRITE_FLUSH,
 261                .mem.type = DM_IO_KMEM,
 262                .mem.ptr.addr = NULL,
 263                .client = ms->io_client,
 264        };
 265
 266        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
 267                io[i].bdev = m->dev->bdev;
 268                io[i].sector = 0;
 269                io[i].count = 0;
 270        }
 271
 272        error_bits = -1;
 273        dm_io(&io_req, ms->nr_mirrors, io, &error_bits);
 274        if (unlikely(error_bits != 0)) {
 275                for (i = 0; i < ms->nr_mirrors; i++)
 276                        if (test_bit(i, &error_bits))
 277                                fail_mirror(ms->mirror + i,
 278                                            DM_RAID1_FLUSH_ERROR);
 279                return -EIO;
 280        }
 281
 282        return 0;
 283}
 284
 285/*-----------------------------------------------------------------
 286 * Recovery.
 287 *
 288 * When a mirror is first activated we may find that some regions
 289 * are in the no-sync state.  We have to recover these by
 290 * recopying from the default mirror to all the others.
 291 *---------------------------------------------------------------*/
 292static void recovery_complete(int read_err, unsigned long write_err,
 293                              void *context)
 294{
 295        struct dm_region *reg = context;
 296        struct mirror_set *ms = dm_rh_region_context(reg);
 297        int m, bit = 0;
 298
 299        if (read_err) {
 300                /* Read error means the failure of default mirror. */
 301                DMERR_LIMIT("Unable to read primary mirror during recovery");
 302                fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR);
 303        }
 304
 305        if (write_err) {
 306                DMERR_LIMIT("Write error during recovery (error = 0x%lx)",
 307                            write_err);
 308                /*
 309                 * Bits correspond to devices (excluding default mirror).
 310                 * The default mirror cannot change during recovery.
 311                 */
 312                for (m = 0; m < ms->nr_mirrors; m++) {
 313                        if (&ms->mirror[m] == get_default_mirror(ms))
 314                                continue;
 315                        if (test_bit(bit, &write_err))
 316                                fail_mirror(ms->mirror + m,
 317                                            DM_RAID1_SYNC_ERROR);
 318                        bit++;
 319                }
 320        }
 321
 322        dm_rh_recovery_end(reg, !(read_err || write_err));
 323}
 324
 325static int recover(struct mirror_set *ms, struct dm_region *reg)
 326{
 327        int r;
 328        unsigned i;
 329        struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest;
 330        struct mirror *m;
 331        unsigned long flags = 0;
 332        region_t key = dm_rh_get_region_key(reg);
 333        sector_t region_size = dm_rh_get_region_size(ms->rh);
 334
 335        /* fill in the source */
 336        m = get_default_mirror(ms);
 337        from.bdev = m->dev->bdev;
 338        from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
 339        if (key == (ms->nr_regions - 1)) {
 340                /*
 341                 * The final region may be smaller than
 342                 * region_size.
 343                 */
 344                from.count = ms->ti->len & (region_size - 1);
 345                if (!from.count)
 346                        from.count = region_size;
 347        } else
 348                from.count = region_size;
 349
 350        /* fill in the destinations */
 351        for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
 352                if (&ms->mirror[i] == get_default_mirror(ms))
 353                        continue;
 354
 355                m = ms->mirror + i;
 356                dest->bdev = m->dev->bdev;
 357                dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
 358                dest->count = from.count;
 359                dest++;
 360        }
 361
 362        /* hand to kcopyd */
 363        if (!errors_handled(ms))
 364                set_bit(DM_KCOPYD_IGNORE_ERROR, &flags);
 365
 366        r = dm_kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to,
 367                           flags, recovery_complete, reg);
 368
 369        return r;
 370}
 371
 372static void do_recovery(struct mirror_set *ms)
 373{
 374        struct dm_region *reg;
 375        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 376        int r;
 377
 378        /*
 379         * Start quiescing some regions.
 380         */
 381        dm_rh_recovery_prepare(ms->rh);
 382
 383        /*
 384         * Copy any already quiesced regions.
 385         */
 386        while ((reg = dm_rh_recovery_start(ms->rh))) {
 387                r = recover(ms, reg);
 388                if (r)
 389                        dm_rh_recovery_end(reg, 0);
 390        }
 391
 392        /*
 393         * Update the in sync flag.
 394         */
 395        if (!ms->in_sync &&
 396            (log->type->get_sync_count(log) == ms->nr_regions)) {
 397                /* the sync is complete */
 398                dm_table_event(ms->ti->table);
 399                ms->in_sync = 1;
 400        }
 401}
 402
 403/*-----------------------------------------------------------------
 404 * Reads
 405 *---------------------------------------------------------------*/
 406static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
 407{
 408        struct mirror *m = get_default_mirror(ms);
 409
 410        do {
 411                if (likely(!atomic_read(&m->error_count)))
 412                        return m;
 413
 414                if (m-- == ms->mirror)
 415                        m += ms->nr_mirrors;
 416        } while (m != get_default_mirror(ms));
 417
 418        return NULL;
 419}
 420
 421static int default_ok(struct mirror *m)
 422{
 423        struct mirror *default_mirror = get_default_mirror(m->ms);
 424
 425        return !atomic_read(&default_mirror->error_count);
 426}
 427
 428static int mirror_available(struct mirror_set *ms, struct bio *bio)
 429{
 430        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 431        region_t region = dm_rh_bio_to_region(ms->rh, bio);
 432
 433        if (log->type->in_sync(log, region, 0))
 434                return choose_mirror(ms,  bio->bi_sector) ? 1 : 0;
 435
 436        return 0;
 437}
 438
 439/*
 440 * remap a buffer to a particular mirror.
 441 */
 442static sector_t map_sector(struct mirror *m, struct bio *bio)
 443{
 444        if (unlikely(!bio->bi_size))
 445                return 0;
 446        return m->offset + dm_target_offset(m->ms->ti, bio->bi_sector);
 447}
 448
 449static void map_bio(struct mirror *m, struct bio *bio)
 450{
 451        bio->bi_bdev = m->dev->bdev;
 452        bio->bi_sector = map_sector(m, bio);
 453}
 454
 455static void map_region(struct dm_io_region *io, struct mirror *m,
 456                       struct bio *bio)
 457{
 458        io->bdev = m->dev->bdev;
 459        io->sector = map_sector(m, bio);
 460        io->count = bio->bi_size >> 9;
 461}
 462
 463static void hold_bio(struct mirror_set *ms, struct bio *bio)
 464{
 465        /*
 466         * Lock is required to avoid race condition during suspend
 467         * process.
 468         */
 469        spin_lock_irq(&ms->lock);
 470
 471        if (atomic_read(&ms->suspend)) {
 472                spin_unlock_irq(&ms->lock);
 473
 474                /*
 475                 * If device is suspended, complete the bio.
 476                 */
 477                if (dm_noflush_suspending(ms->ti))
 478                        bio_endio(bio, DM_ENDIO_REQUEUE);
 479                else
 480                        bio_endio(bio, -EIO);
 481                return;
 482        }
 483
 484        /*
 485         * Hold bio until the suspend is complete.
 486         */
 487        bio_list_add(&ms->holds, bio);
 488        spin_unlock_irq(&ms->lock);
 489}
 490
 491/*-----------------------------------------------------------------
 492 * Reads
 493 *---------------------------------------------------------------*/
 494static void read_callback(unsigned long error, void *context)
 495{
 496        struct bio *bio = context;
 497        struct mirror *m;
 498
 499        m = bio_get_m(bio);
 500        bio_set_m(bio, NULL);
 501
 502        if (likely(!error)) {
 503                bio_endio(bio, 0);
 504                return;
 505        }
 506
 507        fail_mirror(m, DM_RAID1_READ_ERROR);
 508
 509        if (likely(default_ok(m)) || mirror_available(m->ms, bio)) {
 510                DMWARN_LIMIT("Read failure on mirror device %s.  "
 511                             "Trying alternative device.",
 512                             m->dev->name);
 513                queue_bio(m->ms, bio, bio_rw(bio));
 514                return;
 515        }
 516
 517        DMERR_LIMIT("Read failure on mirror device %s.  Failing I/O.",
 518                    m->dev->name);
 519        bio_endio(bio, -EIO);
 520}
 521
 522/* Asynchronous read. */
 523static void read_async_bio(struct mirror *m, struct bio *bio)
 524{
 525        struct dm_io_region io;
 526        struct dm_io_request io_req = {
 527                .bi_rw = READ,
 528                .mem.type = DM_IO_BVEC,
 529                .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
 530                .notify.fn = read_callback,
 531                .notify.context = bio,
 532                .client = m->ms->io_client,
 533        };
 534
 535        map_region(&io, m, bio);
 536        bio_set_m(bio, m);
 537        BUG_ON(dm_io(&io_req, 1, &io, NULL));
 538}
 539
 540static inline int region_in_sync(struct mirror_set *ms, region_t region,
 541                                 int may_block)
 542{
 543        int state = dm_rh_get_state(ms->rh, region, may_block);
 544        return state == DM_RH_CLEAN || state == DM_RH_DIRTY;
 545}
 546
 547static void do_reads(struct mirror_set *ms, struct bio_list *reads)
 548{
 549        region_t region;
 550        struct bio *bio;
 551        struct mirror *m;
 552
 553        while ((bio = bio_list_pop(reads))) {
 554                region = dm_rh_bio_to_region(ms->rh, bio);
 555                m = get_default_mirror(ms);
 556
 557                /*
 558                 * We can only read balance if the region is in sync.
 559                 */
 560                if (likely(region_in_sync(ms, region, 1)))
 561                        m = choose_mirror(ms, bio->bi_sector);
 562                else if (m && atomic_read(&m->error_count))
 563                        m = NULL;
 564
 565                if (likely(m))
 566                        read_async_bio(m, bio);
 567                else
 568                        bio_endio(bio, -EIO);
 569        }
 570}
 571
 572/*-----------------------------------------------------------------
 573 * Writes.
 574 *
 575 * We do different things with the write io depending on the
 576 * state of the region that it's in:
 577 *
 578 * SYNC:        increment pending, use kcopyd to write to *all* mirrors
 579 * RECOVERING:  delay the io until recovery completes
 580 * NOSYNC:      increment pending, just write to the default mirror
 581 *---------------------------------------------------------------*/
 582
 583
 584static void write_callback(unsigned long error, void *context)
 585{
 586        unsigned i, ret = 0;
 587        struct bio *bio = (struct bio *) context;
 588        struct mirror_set *ms;
 589        int should_wake = 0;
 590        unsigned long flags;
 591
 592        ms = bio_get_m(bio)->ms;
 593        bio_set_m(bio, NULL);
 594
 595        /*
 596         * NOTE: We don't decrement the pending count here,
 597         * instead it is done by the targets endio function.
 598         * This way we handle both writes to SYNC and NOSYNC
 599         * regions with the same code.
 600         */
 601        if (likely(!error)) {
 602                bio_endio(bio, ret);
 603                return;
 604        }
 605
 606        for (i = 0; i < ms->nr_mirrors; i++)
 607                if (test_bit(i, &error))
 608                        fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
 609
 610        /*
 611         * Need to raise event.  Since raising
 612         * events can block, we need to do it in
 613         * the main thread.
 614         */
 615        spin_lock_irqsave(&ms->lock, flags);
 616        if (!ms->failures.head)
 617                should_wake = 1;
 618        bio_list_add(&ms->failures, bio);
 619        spin_unlock_irqrestore(&ms->lock, flags);
 620        if (should_wake)
 621                wakeup_mirrord(ms);
 622}
 623
 624static void do_write(struct mirror_set *ms, struct bio *bio)
 625{
 626        unsigned int i;
 627        struct dm_io_region io[ms->nr_mirrors], *dest = io;
 628        struct mirror *m;
 629        struct dm_io_request io_req = {
 630                .bi_rw = WRITE | (bio->bi_rw & WRITE_FLUSH_FUA),
 631                .mem.type = DM_IO_BVEC,
 632                .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
 633                .notify.fn = write_callback,
 634                .notify.context = bio,
 635                .client = ms->io_client,
 636        };
 637
 638        if (bio->bi_rw & REQ_DISCARD) {
 639                io_req.bi_rw |= REQ_DISCARD;
 640                io_req.mem.type = DM_IO_KMEM;
 641                io_req.mem.ptr.addr = NULL;
 642        }
 643
 644        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
 645                map_region(dest++, m, bio);
 646
 647        /*
 648         * Use default mirror because we only need it to retrieve the reference
 649         * to the mirror set in write_callback().
 650         */
 651        bio_set_m(bio, get_default_mirror(ms));
 652
 653        BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL));
 654}
 655
 656static void do_writes(struct mirror_set *ms, struct bio_list *writes)
 657{
 658        int state;
 659        struct bio *bio;
 660        struct bio_list sync, nosync, recover, *this_list = NULL;
 661        struct bio_list requeue;
 662        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 663        region_t region;
 664
 665        if (!writes->head)
 666                return;
 667
 668        /*
 669         * Classify each write.
 670         */
 671        bio_list_init(&sync);
 672        bio_list_init(&nosync);
 673        bio_list_init(&recover);
 674        bio_list_init(&requeue);
 675
 676        while ((bio = bio_list_pop(writes))) {
 677                if ((bio->bi_rw & REQ_FLUSH) ||
 678                    (bio->bi_rw & REQ_DISCARD)) {
 679                        bio_list_add(&sync, bio);
 680                        continue;
 681                }
 682
 683                region = dm_rh_bio_to_region(ms->rh, bio);
 684
 685                if (log->type->is_remote_recovering &&
 686                    log->type->is_remote_recovering(log, region)) {
 687                        bio_list_add(&requeue, bio);
 688                        continue;
 689                }
 690
 691                state = dm_rh_get_state(ms->rh, region, 1);
 692                switch (state) {
 693                case DM_RH_CLEAN:
 694                case DM_RH_DIRTY:
 695                        this_list = &sync;
 696                        break;
 697
 698                case DM_RH_NOSYNC:
 699                        this_list = &nosync;
 700                        break;
 701
 702                case DM_RH_RECOVERING:
 703                        this_list = &recover;
 704                        break;
 705                }
 706
 707                bio_list_add(this_list, bio);
 708        }
 709
 710        /*
 711         * Add bios that are delayed due to remote recovery
 712         * back on to the write queue
 713         */
 714        if (unlikely(requeue.head)) {
 715                spin_lock_irq(&ms->lock);
 716                bio_list_merge(&ms->writes, &requeue);
 717                spin_unlock_irq(&ms->lock);
 718                delayed_wake(ms);
 719        }
 720
 721        /*
 722         * Increment the pending counts for any regions that will
 723         * be written to (writes to recover regions are going to
 724         * be delayed).
 725         */
 726        dm_rh_inc_pending(ms->rh, &sync);
 727        dm_rh_inc_pending(ms->rh, &nosync);
 728
 729        /*
 730         * If the flush fails on a previous call and succeeds here,
 731         * we must not reset the log_failure variable.  We need
 732         * userspace interaction to do that.
 733         */
 734        ms->log_failure = dm_rh_flush(ms->rh) ? 1 : ms->log_failure;
 735
 736        /*
 737         * Dispatch io.
 738         */
 739        if (unlikely(ms->log_failure) && errors_handled(ms)) {
 740                spin_lock_irq(&ms->lock);
 741                bio_list_merge(&ms->failures, &sync);
 742                spin_unlock_irq(&ms->lock);
 743                wakeup_mirrord(ms);
 744        } else
 745                while ((bio = bio_list_pop(&sync)))
 746                        do_write(ms, bio);
 747
 748        while ((bio = bio_list_pop(&recover)))
 749                dm_rh_delay(ms->rh, bio);
 750
 751        while ((bio = bio_list_pop(&nosync))) {
 752                if (unlikely(ms->leg_failure) && errors_handled(ms)) {
 753                        spin_lock_irq(&ms->lock);
 754                        bio_list_add(&ms->failures, bio);
 755                        spin_unlock_irq(&ms->lock);
 756                        wakeup_mirrord(ms);
 757                } else {
 758                        map_bio(get_default_mirror(ms), bio);
 759                        generic_make_request(bio);
 760                }
 761        }
 762}
 763
 764static void do_failures(struct mirror_set *ms, struct bio_list *failures)
 765{
 766        struct bio *bio;
 767
 768        if (likely(!failures->head))
 769                return;
 770
 771        /*
 772         * If the log has failed, unattempted writes are being
 773         * put on the holds list.  We can't issue those writes
 774         * until a log has been marked, so we must store them.
 775         *
 776         * If a 'noflush' suspend is in progress, we can requeue
 777         * the I/O's to the core.  This give userspace a chance
 778         * to reconfigure the mirror, at which point the core
 779         * will reissue the writes.  If the 'noflush' flag is
 780         * not set, we have no choice but to return errors.
 781         *
 782         * Some writes on the failures list may have been
 783         * submitted before the log failure and represent a
 784         * failure to write to one of the devices.  It is ok
 785         * for us to treat them the same and requeue them
 786         * as well.
 787         */
 788        while ((bio = bio_list_pop(failures))) {
 789                if (!ms->log_failure) {
 790                        ms->in_sync = 0;
 791                        dm_rh_mark_nosync(ms->rh, bio);
 792                }
 793
 794                /*
 795                 * If all the legs are dead, fail the I/O.
 796                 * If we have been told to handle errors, hold the bio
 797                 * and wait for userspace to deal with the problem.
 798                 * Otherwise pretend that the I/O succeeded. (This would
 799                 * be wrong if the failed leg returned after reboot and
 800                 * got replicated back to the good legs.)
 801                 */
 802                if (!get_valid_mirror(ms))
 803                        bio_endio(bio, -EIO);
 804                else if (errors_handled(ms))
 805                        hold_bio(ms, bio);
 806                else
 807                        bio_endio(bio, 0);
 808        }
 809}
 810
 811static void trigger_event(struct work_struct *work)
 812{
 813        struct mirror_set *ms =
 814                container_of(work, struct mirror_set, trigger_event);
 815
 816        dm_table_event(ms->ti->table);
 817}
 818
 819/*-----------------------------------------------------------------
 820 * kmirrord
 821 *---------------------------------------------------------------*/
 822static void do_mirror(struct work_struct *work)
 823{
 824        struct mirror_set *ms = container_of(work, struct mirror_set,
 825                                             kmirrord_work);
 826        struct bio_list reads, writes, failures;
 827        unsigned long flags;
 828
 829        spin_lock_irqsave(&ms->lock, flags);
 830        reads = ms->reads;
 831        writes = ms->writes;
 832        failures = ms->failures;
 833        bio_list_init(&ms->reads);
 834        bio_list_init(&ms->writes);
 835        bio_list_init(&ms->failures);
 836        spin_unlock_irqrestore(&ms->lock, flags);
 837
 838        dm_rh_update_states(ms->rh, errors_handled(ms));
 839        do_recovery(ms);
 840        do_reads(ms, &reads);
 841        do_writes(ms, &writes);
 842        do_failures(ms, &failures);
 843}
 844
 845/*-----------------------------------------------------------------
 846 * Target functions
 847 *---------------------------------------------------------------*/
 848static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 849                                        uint32_t region_size,
 850                                        struct dm_target *ti,
 851                                        struct dm_dirty_log *dl)
 852{
 853        size_t len;
 854        struct mirror_set *ms = NULL;
 855
 856        len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
 857
 858        ms = kzalloc(len, GFP_KERNEL);
 859        if (!ms) {
 860                ti->error = "Cannot allocate mirror context";
 861                return NULL;
 862        }
 863
 864        spin_lock_init(&ms->lock);
 865        bio_list_init(&ms->reads);
 866        bio_list_init(&ms->writes);
 867        bio_list_init(&ms->failures);
 868        bio_list_init(&ms->holds);
 869
 870        ms->ti = ti;
 871        ms->nr_mirrors = nr_mirrors;
 872        ms->nr_regions = dm_sector_div_up(ti->len, region_size);
 873        ms->in_sync = 0;
 874        ms->log_failure = 0;
 875        ms->leg_failure = 0;
 876        atomic_set(&ms->suspend, 0);
 877        atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
 878
 879        ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS,
 880                                                _dm_raid1_read_record_cache);
 881
 882        if (!ms->read_record_pool) {
 883                ti->error = "Error creating mirror read_record_pool";
 884                kfree(ms);
 885                return NULL;
 886        }
 887
 888        ms->io_client = dm_io_client_create();
 889        if (IS_ERR(ms->io_client)) {
 890                ti->error = "Error creating dm_io client";
 891                mempool_destroy(ms->read_record_pool);
 892                kfree(ms);
 893                return NULL;
 894        }
 895
 896        ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord,
 897                                       wakeup_all_recovery_waiters,
 898                                       ms->ti->begin, MAX_RECOVERY,
 899                                       dl, region_size, ms->nr_regions);
 900        if (IS_ERR(ms->rh)) {
 901                ti->error = "Error creating dirty region hash";
 902                dm_io_client_destroy(ms->io_client);
 903                mempool_destroy(ms->read_record_pool);
 904                kfree(ms);
 905                return NULL;
 906        }
 907
 908        return ms;
 909}
 910
 911static void free_context(struct mirror_set *ms, struct dm_target *ti,
 912                         unsigned int m)
 913{
 914        while (m--)
 915                dm_put_device(ti, ms->mirror[m].dev);
 916
 917        dm_io_client_destroy(ms->io_client);
 918        dm_region_hash_destroy(ms->rh);
 919        mempool_destroy(ms->read_record_pool);
 920        kfree(ms);
 921}
 922
 923static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
 924                      unsigned int mirror, char **argv)
 925{
 926        unsigned long long offset;
 927        char dummy;
 928
 929        if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1) {
 930                ti->error = "Invalid offset";
 931                return -EINVAL;
 932        }
 933
 934        if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
 935                          &ms->mirror[mirror].dev)) {
 936                ti->error = "Device lookup failure";
 937                return -ENXIO;
 938        }
 939
 940        ms->mirror[mirror].ms = ms;
 941        atomic_set(&(ms->mirror[mirror].error_count), 0);
 942        ms->mirror[mirror].error_type = 0;
 943        ms->mirror[mirror].offset = offset;
 944
 945        return 0;
 946}
 947
 948/*
 949 * Create dirty log: log_type #log_params <log_params>
 950 */
 951static struct dm_dirty_log *create_dirty_log(struct dm_target *ti,
 952                                             unsigned argc, char **argv,
 953                                             unsigned *args_used)
 954{
 955        unsigned param_count;
 956        struct dm_dirty_log *dl;
 957        char dummy;
 958
 959        if (argc < 2) {
 960                ti->error = "Insufficient mirror log arguments";
 961                return NULL;
 962        }
 963
 964        if (sscanf(argv[1], "%u%c", &param_count, &dummy) != 1) {
 965                ti->error = "Invalid mirror log argument count";
 966                return NULL;
 967        }
 968
 969        *args_used = 2 + param_count;
 970
 971        if (argc < *args_used) {
 972                ti->error = "Insufficient mirror log arguments";
 973                return NULL;
 974        }
 975
 976        dl = dm_dirty_log_create(argv[0], ti, mirror_flush, param_count,
 977                                 argv + 2);
 978        if (!dl) {
 979                ti->error = "Error creating mirror dirty log";
 980                return NULL;
 981        }
 982
 983        return dl;
 984}
 985
 986static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
 987                          unsigned *args_used)
 988{
 989        unsigned num_features;
 990        struct dm_target *ti = ms->ti;
 991        char dummy;
 992
 993        *args_used = 0;
 994
 995        if (!argc)
 996                return 0;
 997
 998        if (sscanf(argv[0], "%u%c", &num_features, &dummy) != 1) {
 999                ti->error = "Invalid number of features";
1000                return -EINVAL;
1001        }
1002
1003        argc--;
1004        argv++;
1005        (*args_used)++;
1006
1007        if (num_features > argc) {
1008                ti->error = "Not enough arguments to support feature count";
1009                return -EINVAL;
1010        }
1011
1012        if (!strcmp("handle_errors", argv[0]))
1013                ms->features |= DM_RAID1_HANDLE_ERRORS;
1014        else {
1015                ti->error = "Unrecognised feature requested";
1016                return -EINVAL;
1017        }
1018
1019        (*args_used)++;
1020
1021        return 0;
1022}
1023
1024/*
1025 * Construct a mirror mapping:
1026 *
1027 * log_type #log_params <log_params>
1028 * #mirrors [mirror_path offset]{2,}
1029 * [#features <features>]
1030 *
1031 * log_type is "core" or "disk"
1032 * #log_params is between 1 and 3
1033 *
1034 * If present, features must be "handle_errors".
1035 */
1036static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1037{
1038        int r;
1039        unsigned int nr_mirrors, m, args_used;
1040        struct mirror_set *ms;
1041        struct dm_dirty_log *dl;
1042        char dummy;
1043
1044        dl = create_dirty_log(ti, argc, argv, &args_used);
1045        if (!dl)
1046                return -EINVAL;
1047
1048        argv += args_used;
1049        argc -= args_used;
1050
1051        if (!argc || sscanf(argv[0], "%u%c", &nr_mirrors, &dummy) != 1 ||
1052            nr_mirrors < 2 || nr_mirrors > DM_KCOPYD_MAX_REGIONS + 1) {
1053                ti->error = "Invalid number of mirrors";
1054                dm_dirty_log_destroy(dl);
1055                return -EINVAL;
1056        }
1057
1058        argv++, argc--;
1059
1060        if (argc < nr_mirrors * 2) {
1061                ti->error = "Too few mirror arguments";
1062                dm_dirty_log_destroy(dl);
1063                return -EINVAL;
1064        }
1065
1066        ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
1067        if (!ms) {
1068                dm_dirty_log_destroy(dl);
1069                return -ENOMEM;
1070        }
1071
1072        /* Get the mirror parameter sets */
1073        for (m = 0; m < nr_mirrors; m++) {
1074                r = get_mirror(ms, ti, m, argv);
1075                if (r) {
1076                        free_context(ms, ti, m);
1077                        return r;
1078                }
1079                argv += 2;
1080                argc -= 2;
1081        }
1082
1083        ti->private = ms;
1084
1085        r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
1086        if (r)
1087                goto err_free_context;
1088
1089        ti->num_flush_requests = 1;
1090        ti->num_discard_requests = 1;
1091        ti->discard_zeroes_data_unsupported = true;
1092
1093        ms->kmirrord_wq = alloc_workqueue("kmirrord",
1094                                          WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
1095        if (!ms->kmirrord_wq) {
1096                DMERR("couldn't start kmirrord");
1097                r = -ENOMEM;
1098                goto err_free_context;
1099        }
1100        INIT_WORK(&ms->kmirrord_work, do_mirror);
1101        init_timer(&ms->timer);
1102        ms->timer_pending = 0;
1103        INIT_WORK(&ms->trigger_event, trigger_event);
1104
1105        r = parse_features(ms, argc, argv, &args_used);
1106        if (r)
1107                goto err_destroy_wq;
1108
1109        argv += args_used;
1110        argc -= args_used;
1111
1112        /*
1113         * Any read-balancing addition depends on the
1114         * DM_RAID1_HANDLE_ERRORS flag being present.
1115         * This is because the decision to balance depends
1116         * on the sync state of a region.  If the above
1117         * flag is not present, we ignore errors; and
1118         * the sync state may be inaccurate.
1119         */
1120
1121        if (argc) {
1122                ti->error = "Too many mirror arguments";
1123                r = -EINVAL;
1124                goto err_destroy_wq;
1125        }
1126
1127        ms->kcopyd_client = dm_kcopyd_client_create();
1128        if (IS_ERR(ms->kcopyd_client)) {
1129                r = PTR_ERR(ms->kcopyd_client);
1130                goto err_destroy_wq;
1131        }
1132
1133        wakeup_mirrord(ms);
1134        return 0;
1135
1136err_destroy_wq:
1137        destroy_workqueue(ms->kmirrord_wq);
1138err_free_context:
1139        free_context(ms, ti, ms->nr_mirrors);
1140        return r;
1141}
1142
1143static void mirror_dtr(struct dm_target *ti)
1144{
1145        struct mirror_set *ms = (struct mirror_set *) ti->private;
1146
1147        del_timer_sync(&ms->timer);
1148        flush_workqueue(ms->kmirrord_wq);
1149        flush_work(&ms->trigger_event);
1150        dm_kcopyd_client_destroy(ms->kcopyd_client);
1151        destroy_workqueue(ms->kmirrord_wq);
1152        free_context(ms, ti, ms->nr_mirrors);
1153}
1154
1155/*
1156 * Mirror mapping function
1157 */
1158static int mirror_map(struct dm_target *ti, struct bio *bio,
1159                      union map_info *map_context)
1160{
1161        int r, rw = bio_rw(bio);
1162        struct mirror *m;
1163        struct mirror_set *ms = ti->private;
1164        struct dm_raid1_read_record *read_record = NULL;
1165        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1166
1167        if (rw == WRITE) {
1168                /* Save region for mirror_end_io() handler */
1169                map_context->ll = dm_rh_bio_to_region(ms->rh, bio);
1170                queue_bio(ms, bio, rw);
1171                return DM_MAPIO_SUBMITTED;
1172        }
1173
1174        r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
1175        if (r < 0 && r != -EWOULDBLOCK)
1176                return r;
1177
1178        /*
1179         * If region is not in-sync queue the bio.
1180         */
1181        if (!r || (r == -EWOULDBLOCK)) {
1182                if (rw == READA)
1183                        return -EWOULDBLOCK;
1184
1185                queue_bio(ms, bio, rw);
1186                return DM_MAPIO_SUBMITTED;
1187        }
1188
1189        /*
1190         * The region is in-sync and we can perform reads directly.
1191         * Store enough information so we can retry if it fails.
1192         */
1193        m = choose_mirror(ms, bio->bi_sector);
1194        if (unlikely(!m))
1195                return -EIO;
1196
1197        read_record = mempool_alloc(ms->read_record_pool, GFP_NOIO);
1198        if (likely(read_record)) {
1199                dm_bio_record(&read_record->details, bio);
1200                map_context->ptr = read_record;
1201                read_record->m = m;
1202        }
1203
1204        map_bio(m, bio);
1205
1206        return DM_MAPIO_REMAPPED;
1207}
1208
1209static int mirror_end_io(struct dm_target *ti, struct bio *bio,
1210                         int error, union map_info *map_context)
1211{
1212        int rw = bio_rw(bio);
1213        struct mirror_set *ms = (struct mirror_set *) ti->private;
1214        struct mirror *m = NULL;
1215        struct dm_bio_details *bd = NULL;
1216        struct dm_raid1_read_record *read_record = map_context->ptr;
1217
1218        /*
1219         * We need to dec pending if this was a write.
1220         */
1221        if (rw == WRITE) {
1222                if (!(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD)))
1223                        dm_rh_dec(ms->rh, map_context->ll);
1224                return error;
1225        }
1226
1227        if (error == -EOPNOTSUPP)
1228                goto out;
1229
1230        if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
1231                goto out;
1232
1233        if (unlikely(error)) {
1234                if (!read_record) {
1235                        /*
1236                         * There wasn't enough memory to record necessary
1237                         * information for a retry or there was no other
1238                         * mirror in-sync.
1239                         */
1240                        DMERR_LIMIT("Mirror read failed.");
1241                        return -EIO;
1242                }
1243
1244                m = read_record->m;
1245
1246                DMERR("Mirror read failed from %s. Trying alternative device.",
1247                      m->dev->name);
1248
1249                fail_mirror(m, DM_RAID1_READ_ERROR);
1250
1251                /*
1252                 * A failed read is requeued for another attempt using an intact
1253                 * mirror.
1254                 */
1255                if (default_ok(m) || mirror_available(ms, bio)) {
1256                        bd = &read_record->details;
1257
1258                        dm_bio_restore(bd, bio);
1259                        mempool_free(read_record, ms->read_record_pool);
1260                        map_context->ptr = NULL;
1261                        queue_bio(ms, bio, rw);
1262                        return 1;
1263                }
1264                DMERR("All replicated volumes dead, failing I/O");
1265        }
1266
1267out:
1268        if (read_record) {
1269                mempool_free(read_record, ms->read_record_pool);
1270                map_context->ptr = NULL;
1271        }
1272
1273        return error;
1274}
1275
1276static void mirror_presuspend(struct dm_target *ti)
1277{
1278        struct mirror_set *ms = (struct mirror_set *) ti->private;
1279        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1280
1281        struct bio_list holds;
1282        struct bio *bio;
1283
1284        atomic_set(&ms->suspend, 1);
1285
1286        /*
1287         * Process bios in the hold list to start recovery waiting
1288         * for bios in the hold list. After the process, no bio has
1289         * a chance to be added in the hold list because ms->suspend
1290         * is set.
1291         */
1292        spin_lock_irq(&ms->lock);
1293        holds = ms->holds;
1294        bio_list_init(&ms->holds);
1295        spin_unlock_irq(&ms->lock);
1296
1297        while ((bio = bio_list_pop(&holds)))
1298                hold_bio(ms, bio);
1299
1300        /*
1301         * We must finish up all the work that we've
1302         * generated (i.e. recovery work).
1303         */
1304        dm_rh_stop_recovery(ms->rh);
1305
1306        wait_event(_kmirrord_recovery_stopped,
1307                   !dm_rh_recovery_in_flight(ms->rh));
1308
1309        if (log->type->presuspend && log->type->presuspend(log))
1310                /* FIXME: need better error handling */
1311                DMWARN("log presuspend failed");
1312
1313        /*
1314         * Now that recovery is complete/stopped and the
1315         * delayed bios are queued, we need to wait for
1316         * the worker thread to complete.  This way,
1317         * we know that all of our I/O has been pushed.
1318         */
1319        flush_workqueue(ms->kmirrord_wq);
1320}
1321
1322static void mirror_postsuspend(struct dm_target *ti)
1323{
1324        struct mirror_set *ms = ti->private;
1325        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1326
1327        if (log->type->postsuspend && log->type->postsuspend(log))
1328                /* FIXME: need better error handling */
1329                DMWARN("log postsuspend failed");
1330}
1331
1332static void mirror_resume(struct dm_target *ti)
1333{
1334        struct mirror_set *ms = ti->private;
1335        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1336
1337        atomic_set(&ms->suspend, 0);
1338        if (log->type->resume && log->type->resume(log))
1339                /* FIXME: need better error handling */
1340                DMWARN("log resume failed");
1341        dm_rh_start_recovery(ms->rh);
1342}
1343
1344/*
1345 * device_status_char
1346 * @m: mirror device/leg we want the status of
1347 *
1348 * We return one character representing the most severe error
1349 * we have encountered.
1350 *    A => Alive - No failures
1351 *    D => Dead - A write failure occurred leaving mirror out-of-sync
1352 *    S => Sync - A sychronization failure occurred, mirror out-of-sync
1353 *    R => Read - A read failure occurred, mirror data unaffected
1354 *
1355 * Returns: <char>
1356 */
1357static char device_status_char(struct mirror *m)
1358{
1359        if (!atomic_read(&(m->error_count)))
1360                return 'A';
1361
1362        return (test_bit(DM_RAID1_FLUSH_ERROR, &(m->error_type))) ? 'F' :
1363                (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' :
1364                (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' :
1365                (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
1366}
1367
1368
1369static int mirror_status(struct dm_target *ti, status_type_t type,
1370                         unsigned status_flags, char *result, unsigned maxlen)
1371{
1372        unsigned int m, sz = 0;
1373        struct mirror_set *ms = (struct mirror_set *) ti->private;
1374        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1375        char buffer[ms->nr_mirrors + 1];
1376
1377        switch (type) {
1378        case STATUSTYPE_INFO:
1379                DMEMIT("%d ", ms->nr_mirrors);
1380                for (m = 0; m < ms->nr_mirrors; m++) {
1381                        DMEMIT("%s ", ms->mirror[m].dev->name);
1382                        buffer[m] = device_status_char(&(ms->mirror[m]));
1383                }
1384                buffer[m] = '\0';
1385
1386                DMEMIT("%llu/%llu 1 %s ",
1387                      (unsigned long long)log->type->get_sync_count(log),
1388                      (unsigned long long)ms->nr_regions, buffer);
1389
1390                sz += log->type->status(log, type, result+sz, maxlen-sz);
1391
1392                break;
1393
1394        case STATUSTYPE_TABLE:
1395                sz = log->type->status(log, type, result, maxlen);
1396
1397                DMEMIT("%d", ms->nr_mirrors);
1398                for (m = 0; m < ms->nr_mirrors; m++)
1399                        DMEMIT(" %s %llu", ms->mirror[m].dev->name,
1400                               (unsigned long long)ms->mirror[m].offset);
1401
1402                if (ms->features & DM_RAID1_HANDLE_ERRORS)
1403                        DMEMIT(" 1 handle_errors");
1404        }
1405
1406        return 0;
1407}
1408
1409static int mirror_iterate_devices(struct dm_target *ti,
1410                                  iterate_devices_callout_fn fn, void *data)
1411{
1412        struct mirror_set *ms = ti->private;
1413        int ret = 0;
1414        unsigned i;
1415
1416        for (i = 0; !ret && i < ms->nr_mirrors; i++)
1417                ret = fn(ti, ms->mirror[i].dev,
1418                         ms->mirror[i].offset, ti->len, data);
1419
1420        return ret;
1421}
1422
1423static struct target_type mirror_target = {
1424        .name    = "mirror",
1425        .version = {1, 12, 1},
1426        .module  = THIS_MODULE,
1427        .ctr     = mirror_ctr,
1428        .dtr     = mirror_dtr,
1429        .map     = mirror_map,
1430        .end_io  = mirror_end_io,
1431        .presuspend = mirror_presuspend,
1432        .postsuspend = mirror_postsuspend,
1433        .resume  = mirror_resume,
1434        .status  = mirror_status,
1435        .iterate_devices = mirror_iterate_devices,
1436};
1437
1438static int __init dm_mirror_init(void)
1439{
1440        int r;
1441
1442        _dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0);
1443        if (!_dm_raid1_read_record_cache) {
1444                DMERR("Can't allocate dm_raid1_read_record cache");
1445                r = -ENOMEM;
1446                goto bad_cache;
1447        }
1448
1449        r = dm_register_target(&mirror_target);
1450        if (r < 0) {
1451                DMERR("Failed to register mirror target");
1452                goto bad_target;
1453        }
1454
1455        return 0;
1456
1457bad_target:
1458        kmem_cache_destroy(_dm_raid1_read_record_cache);
1459bad_cache:
1460        return r;
1461}
1462
1463static void __exit dm_mirror_exit(void)
1464{
1465        dm_unregister_target(&mirror_target);
1466        kmem_cache_destroy(_dm_raid1_read_record_cache);
1467}
1468
1469/* Module hooks */
1470module_init(dm_mirror_init);
1471module_exit(dm_mirror_exit);
1472
1473MODULE_DESCRIPTION(DM_NAME " mirror target");
1474MODULE_AUTHOR("Joe Thornber");
1475MODULE_LICENSE("GPL");
1476
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