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 MAX_NR_MIRRORS  (DM_KCOPYD_MAX_REGIONS + 1)
  27
  28#define DM_RAID1_HANDLE_ERRORS  0x01
  29#define DM_RAID1_KEEP_LOG       0x02
  30#define errors_handled(p)       ((p)->features & DM_RAID1_HANDLE_ERRORS)
  31#define keep_log(p)             ((p)->features & DM_RAID1_KEEP_LOG)
  32
  33static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
  34
  35/*-----------------------------------------------------------------
  36 * Mirror set structures.
  37 *---------------------------------------------------------------*/
  38enum dm_raid1_error {
  39        DM_RAID1_WRITE_ERROR,
  40        DM_RAID1_FLUSH_ERROR,
  41        DM_RAID1_SYNC_ERROR,
  42        DM_RAID1_READ_ERROR
  43};
  44
  45struct mirror {
  46        struct mirror_set *ms;
  47        atomic_t error_count;
  48        unsigned long error_type;
  49        struct dm_dev *dev;
  50        sector_t offset;
  51};
  52
  53struct mirror_set {
  54        struct dm_target *ti;
  55        struct list_head list;
  56
  57        uint64_t features;
  58
  59        spinlock_t lock;        /* protects the lists */
  60        struct bio_list reads;
  61        struct bio_list writes;
  62        struct bio_list failures;
  63        struct bio_list holds;  /* bios are waiting until suspend */
  64
  65        struct dm_region_hash *rh;
  66        struct dm_kcopyd_client *kcopyd_client;
  67        struct dm_io_client *io_client;
  68
  69        /* recovery */
  70        region_t nr_regions;
  71        int in_sync;
  72        int log_failure;
  73        int leg_failure;
  74        atomic_t suspend;
  75
  76        atomic_t default_mirror;        /* Default mirror */
  77
  78        struct workqueue_struct *kmirrord_wq;
  79        struct work_struct kmirrord_work;
  80        struct timer_list timer;
  81        unsigned long timer_pending;
  82
  83        struct work_struct trigger_event;
  84
  85        unsigned nr_mirrors;
  86        struct mirror mirror[];
  87};
  88
  89DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle,
  90                "A percentage of time allocated for raid resynchronization");
  91
  92static void wakeup_mirrord(void *context)
  93{
  94        struct mirror_set *ms = context;
  95
  96        queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
  97}
  98
  99static void delayed_wake_fn(struct timer_list *t)
 100{
 101        struct mirror_set *ms = from_timer(ms, t, timer);
 102
 103        clear_bit(0, &ms->timer_pending);
 104        wakeup_mirrord(ms);
 105}
 106
 107static void delayed_wake(struct mirror_set *ms)
 108{
 109        if (test_and_set_bit(0, &ms->timer_pending))
 110                return;
 111
 112        ms->timer.expires = jiffies + HZ / 5;
 113        add_timer(&ms->timer);
 114}
 115
 116static void wakeup_all_recovery_waiters(void *context)
 117{
 118        wake_up_all(&_kmirrord_recovery_stopped);
 119}
 120
 121static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
 122{
 123        unsigned long flags;
 124        int should_wake = 0;
 125        struct bio_list *bl;
 126
 127        bl = (rw == WRITE) ? &ms->writes : &ms->reads;
 128        spin_lock_irqsave(&ms->lock, flags);
 129        should_wake = !(bl->head);
 130        bio_list_add(bl, bio);
 131        spin_unlock_irqrestore(&ms->lock, flags);
 132
 133        if (should_wake)
 134                wakeup_mirrord(ms);
 135}
 136
 137static void dispatch_bios(void *context, struct bio_list *bio_list)
 138{
 139        struct mirror_set *ms = context;
 140        struct bio *bio;
 141
 142        while ((bio = bio_list_pop(bio_list)))
 143                queue_bio(ms, bio, WRITE);
 144}
 145
 146struct dm_raid1_bio_record {
 147        struct mirror *m;
 148        /* if details->bi_bdev == NULL, details were not saved */
 149        struct dm_bio_details details;
 150        region_t write_region;
 151};
 152
 153/*
 154 * Every mirror should look like this one.
 155 */
 156#define DEFAULT_MIRROR 0
 157
 158/*
 159 * This is yucky.  We squirrel the mirror struct away inside
 160 * bi_next for read/write buffers.  This is safe since the bh
 161 * doesn't get submitted to the lower levels of block layer.
 162 */
 163static struct mirror *bio_get_m(struct bio *bio)
 164{
 165        return (struct mirror *) bio->bi_next;
 166}
 167
 168static void bio_set_m(struct bio *bio, struct mirror *m)
 169{
 170        bio->bi_next = (struct bio *) m;
 171}
 172
 173static struct mirror *get_default_mirror(struct mirror_set *ms)
 174{
 175        return &ms->mirror[atomic_read(&ms->default_mirror)];
 176}
 177
 178static void set_default_mirror(struct mirror *m)
 179{
 180        struct mirror_set *ms = m->ms;
 181        struct mirror *m0 = &(ms->mirror[0]);
 182
 183        atomic_set(&ms->default_mirror, m - m0);
 184}
 185
 186static struct mirror *get_valid_mirror(struct mirror_set *ms)
 187{
 188        struct mirror *m;
 189
 190        for (m = ms->mirror; m < ms->mirror + ms->nr_mirrors; m++)
 191                if (!atomic_read(&m->error_count))
 192                        return m;
 193
 194        return NULL;
 195}
 196
 197/* fail_mirror
 198 * @m: mirror device to fail
 199 * @error_type: one of the enum's, DM_RAID1_*_ERROR
 200 *
 201 * If errors are being handled, record the type of
 202 * error encountered for this device.  If this type
 203 * of error has already been recorded, we can return;
 204 * otherwise, we must signal userspace by triggering
 205 * an event.  Additionally, if the device is the
 206 * primary device, we must choose a new primary, but
 207 * only if the mirror is in-sync.
 208 *
 209 * This function must not block.
 210 */
 211static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
 212{
 213        struct mirror_set *ms = m->ms;
 214        struct mirror *new;
 215
 216        ms->leg_failure = 1;
 217
 218        /*
 219         * error_count is used for nothing more than a
 220         * simple way to tell if a device has encountered
 221         * errors.
 222         */
 223        atomic_inc(&m->error_count);
 224
 225        if (test_and_set_bit(error_type, &m->error_type))
 226                return;
 227
 228        if (!errors_handled(ms))
 229                return;
 230
 231        if (m != get_default_mirror(ms))
 232                goto out;
 233
 234        if (!ms->in_sync && !keep_log(ms)) {
 235                /*
 236                 * Better to issue requests to same failing device
 237                 * than to risk returning corrupt data.
 238                 */
 239                DMERR("Primary mirror (%s) failed while out-of-sync: "
 240                      "Reads may fail.", m->dev->name);
 241                goto out;
 242        }
 243
 244        new = get_valid_mirror(ms);
 245        if (new)
 246                set_default_mirror(new);
 247        else
 248                DMWARN("All sides of mirror have failed.");
 249
 250out:
 251        schedule_work(&ms->trigger_event);
 252}
 253
 254static int mirror_flush(struct dm_target *ti)
 255{
 256        struct mirror_set *ms = ti->private;
 257        unsigned long error_bits;
 258
 259        unsigned int i;
 260        struct dm_io_region io[MAX_NR_MIRRORS];
 261        struct mirror *m;
 262        struct dm_io_request io_req = {
 263                .bi_op = REQ_OP_WRITE,
 264                .bi_op_flags = REQ_PREFLUSH | REQ_SYNC,
 265                .mem.type = DM_IO_KMEM,
 266                .mem.ptr.addr = NULL,
 267                .client = ms->io_client,
 268        };
 269
 270        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
 271                io[i].bdev = m->dev->bdev;
 272                io[i].sector = 0;
 273                io[i].count = 0;
 274        }
 275
 276        error_bits = -1;
 277        dm_io(&io_req, ms->nr_mirrors, io, &error_bits);
 278        if (unlikely(error_bits != 0)) {
 279                for (i = 0; i < ms->nr_mirrors; i++)
 280                        if (test_bit(i, &error_bits))
 281                                fail_mirror(ms->mirror + i,
 282                                            DM_RAID1_FLUSH_ERROR);
 283                return -EIO;
 284        }
 285
 286        return 0;
 287}
 288
 289/*-----------------------------------------------------------------
 290 * Recovery.
 291 *
 292 * When a mirror is first activated we may find that some regions
 293 * are in the no-sync state.  We have to recover these by
 294 * recopying from the default mirror to all the others.
 295 *---------------------------------------------------------------*/
 296static void recovery_complete(int read_err, unsigned long write_err,
 297                              void *context)
 298{
 299        struct dm_region *reg = context;
 300        struct mirror_set *ms = dm_rh_region_context(reg);
 301        int m, bit = 0;
 302
 303        if (read_err) {
 304                /* Read error means the failure of default mirror. */
 305                DMERR_LIMIT("Unable to read primary mirror during recovery");
 306                fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR);
 307        }
 308
 309        if (write_err) {
 310                DMERR_LIMIT("Write error during recovery (error = 0x%lx)",
 311                            write_err);
 312                /*
 313                 * Bits correspond to devices (excluding default mirror).
 314                 * The default mirror cannot change during recovery.
 315                 */
 316                for (m = 0; m < ms->nr_mirrors; m++) {
 317                        if (&ms->mirror[m] == get_default_mirror(ms))
 318                                continue;
 319                        if (test_bit(bit, &write_err))
 320                                fail_mirror(ms->mirror + m,
 321                                            DM_RAID1_SYNC_ERROR);
 322                        bit++;
 323                }
 324        }
 325
 326        dm_rh_recovery_end(reg, !(read_err || write_err));
 327}
 328
 329static void recover(struct mirror_set *ms, struct dm_region *reg)
 330{
 331        unsigned i;
 332        struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest;
 333        struct mirror *m;
 334        unsigned long flags = 0;
 335        region_t key = dm_rh_get_region_key(reg);
 336        sector_t region_size = dm_rh_get_region_size(ms->rh);
 337
 338        /* fill in the source */
 339        m = get_default_mirror(ms);
 340        from.bdev = m->dev->bdev;
 341        from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
 342        if (key == (ms->nr_regions - 1)) {
 343                /*
 344                 * The final region may be smaller than
 345                 * region_size.
 346                 */
 347                from.count = ms->ti->len & (region_size - 1);
 348                if (!from.count)
 349                        from.count = region_size;
 350        } else
 351                from.count = region_size;
 352
 353        /* fill in the destinations */
 354        for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
 355                if (&ms->mirror[i] == get_default_mirror(ms))
 356                        continue;
 357
 358                m = ms->mirror + i;
 359                dest->bdev = m->dev->bdev;
 360                dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
 361                dest->count = from.count;
 362                dest++;
 363        }
 364
 365        /* hand to kcopyd */
 366        if (!errors_handled(ms))
 367                set_bit(DM_KCOPYD_IGNORE_ERROR, &flags);
 368
 369        dm_kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to,
 370                       flags, recovery_complete, reg);
 371}
 372
 373static void reset_ms_flags(struct mirror_set *ms)
 374{
 375        unsigned int m;
 376
 377        ms->leg_failure = 0;
 378        for (m = 0; m < ms->nr_mirrors; m++) {
 379                atomic_set(&(ms->mirror[m].error_count), 0);
 380                ms->mirror[m].error_type = 0;
 381        }
 382}
 383
 384static void do_recovery(struct mirror_set *ms)
 385{
 386        struct dm_region *reg;
 387        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 388
 389        /*
 390         * Start quiescing some regions.
 391         */
 392        dm_rh_recovery_prepare(ms->rh);
 393
 394        /*
 395         * Copy any already quiesced regions.
 396         */
 397        while ((reg = dm_rh_recovery_start(ms->rh)))
 398                recover(ms, reg);
 399
 400        /*
 401         * Update the in sync flag.
 402         */
 403        if (!ms->in_sync &&
 404            (log->type->get_sync_count(log) == ms->nr_regions)) {
 405                /* the sync is complete */
 406                dm_table_event(ms->ti->table);
 407                ms->in_sync = 1;
 408                reset_ms_flags(ms);
 409        }
 410}
 411
 412/*-----------------------------------------------------------------
 413 * Reads
 414 *---------------------------------------------------------------*/
 415static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
 416{
 417        struct mirror *m = get_default_mirror(ms);
 418
 419        do {
 420                if (likely(!atomic_read(&m->error_count)))
 421                        return m;
 422
 423                if (m-- == ms->mirror)
 424                        m += ms->nr_mirrors;
 425        } while (m != get_default_mirror(ms));
 426
 427        return NULL;
 428}
 429
 430static int default_ok(struct mirror *m)
 431{
 432        struct mirror *default_mirror = get_default_mirror(m->ms);
 433
 434        return !atomic_read(&default_mirror->error_count);
 435}
 436
 437static int mirror_available(struct mirror_set *ms, struct bio *bio)
 438{
 439        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 440        region_t region = dm_rh_bio_to_region(ms->rh, bio);
 441
 442        if (log->type->in_sync(log, region, 0))
 443                return choose_mirror(ms,  bio->bi_iter.bi_sector) ? 1 : 0;
 444
 445        return 0;
 446}
 447
 448/*
 449 * remap a buffer to a particular mirror.
 450 */
 451static sector_t map_sector(struct mirror *m, struct bio *bio)
 452{
 453        if (unlikely(!bio->bi_iter.bi_size))
 454                return 0;
 455        return m->offset + dm_target_offset(m->ms->ti, bio->bi_iter.bi_sector);
 456}
 457
 458static void map_bio(struct mirror *m, struct bio *bio)
 459{
 460        bio_set_dev(bio, m->dev->bdev);
 461        bio->bi_iter.bi_sector = map_sector(m, bio);
 462}
 463
 464static void map_region(struct dm_io_region *io, struct mirror *m,
 465                       struct bio *bio)
 466{
 467        io->bdev = m->dev->bdev;
 468        io->sector = map_sector(m, bio);
 469        io->count = bio_sectors(bio);
 470}
 471
 472static void hold_bio(struct mirror_set *ms, struct bio *bio)
 473{
 474        /*
 475         * Lock is required to avoid race condition during suspend
 476         * process.
 477         */
 478        spin_lock_irq(&ms->lock);
 479
 480        if (atomic_read(&ms->suspend)) {
 481                spin_unlock_irq(&ms->lock);
 482
 483                /*
 484                 * If device is suspended, complete the bio.
 485                 */
 486                if (dm_noflush_suspending(ms->ti))
 487                        bio->bi_status = BLK_STS_DM_REQUEUE;
 488                else
 489                        bio->bi_status = BLK_STS_IOERR;
 490
 491                bio_endio(bio);
 492                return;
 493        }
 494
 495        /*
 496         * Hold bio until the suspend is complete.
 497         */
 498        bio_list_add(&ms->holds, bio);
 499        spin_unlock_irq(&ms->lock);
 500}
 501
 502/*-----------------------------------------------------------------
 503 * Reads
 504 *---------------------------------------------------------------*/
 505static void read_callback(unsigned long error, void *context)
 506{
 507        struct bio *bio = context;
 508        struct mirror *m;
 509
 510        m = bio_get_m(bio);
 511        bio_set_m(bio, NULL);
 512
 513        if (likely(!error)) {
 514                bio_endio(bio);
 515                return;
 516        }
 517
 518        fail_mirror(m, DM_RAID1_READ_ERROR);
 519
 520        if (likely(default_ok(m)) || mirror_available(m->ms, bio)) {
 521                DMWARN_LIMIT("Read failure on mirror device %s.  "
 522                             "Trying alternative device.",
 523                             m->dev->name);
 524                queue_bio(m->ms, bio, bio_data_dir(bio));
 525                return;
 526        }
 527
 528        DMERR_LIMIT("Read failure on mirror device %s.  Failing I/O.",
 529                    m->dev->name);
 530        bio_io_error(bio);
 531}
 532
 533/* Asynchronous read. */
 534static void read_async_bio(struct mirror *m, struct bio *bio)
 535{
 536        struct dm_io_region io;
 537        struct dm_io_request io_req = {
 538                .bi_op = REQ_OP_READ,
 539                .bi_op_flags = 0,
 540                .mem.type = DM_IO_BIO,
 541                .mem.ptr.bio = bio,
 542                .notify.fn = read_callback,
 543                .notify.context = bio,
 544                .client = m->ms->io_client,
 545        };
 546
 547        map_region(&io, m, bio);
 548        bio_set_m(bio, m);
 549        BUG_ON(dm_io(&io_req, 1, &io, NULL));
 550}
 551
 552static inline int region_in_sync(struct mirror_set *ms, region_t region,
 553                                 int may_block)
 554{
 555        int state = dm_rh_get_state(ms->rh, region, may_block);
 556        return state == DM_RH_CLEAN || state == DM_RH_DIRTY;
 557}
 558
 559static void do_reads(struct mirror_set *ms, struct bio_list *reads)
 560{
 561        region_t region;
 562        struct bio *bio;
 563        struct mirror *m;
 564
 565        while ((bio = bio_list_pop(reads))) {
 566                region = dm_rh_bio_to_region(ms->rh, bio);
 567                m = get_default_mirror(ms);
 568
 569                /*
 570                 * We can only read balance if the region is in sync.
 571                 */
 572                if (likely(region_in_sync(ms, region, 1)))
 573                        m = choose_mirror(ms, bio->bi_iter.bi_sector);
 574                else if (m && atomic_read(&m->error_count))
 575                        m = NULL;
 576
 577                if (likely(m))
 578                        read_async_bio(m, bio);
 579                else
 580                        bio_io_error(bio);
 581        }
 582}
 583
 584/*-----------------------------------------------------------------
 585 * Writes.
 586 *
 587 * We do different things with the write io depending on the
 588 * state of the region that it's in:
 589 *
 590 * SYNC:        increment pending, use kcopyd to write to *all* mirrors
 591 * RECOVERING:  delay the io until recovery completes
 592 * NOSYNC:      increment pending, just write to the default mirror
 593 *---------------------------------------------------------------*/
 594
 595
 596static void write_callback(unsigned long error, void *context)
 597{
 598        unsigned i;
 599        struct bio *bio = (struct bio *) context;
 600        struct mirror_set *ms;
 601        int should_wake = 0;
 602        unsigned long flags;
 603
 604        ms = bio_get_m(bio)->ms;
 605        bio_set_m(bio, NULL);
 606
 607        /*
 608         * NOTE: We don't decrement the pending count here,
 609         * instead it is done by the targets endio function.
 610         * This way we handle both writes to SYNC and NOSYNC
 611         * regions with the same code.
 612         */
 613        if (likely(!error)) {
 614                bio_endio(bio);
 615                return;
 616        }
 617
 618        /*
 619         * If the bio is discard, return an error, but do not
 620         * degrade the array.
 621         */
 622        if (bio_op(bio) == REQ_OP_DISCARD) {
 623                bio->bi_status = BLK_STS_NOTSUPP;
 624                bio_endio(bio);
 625                return;
 626        }
 627
 628        for (i = 0; i < ms->nr_mirrors; i++)
 629                if (test_bit(i, &error))
 630                        fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
 631
 632        /*
 633         * Need to raise event.  Since raising
 634         * events can block, we need to do it in
 635         * the main thread.
 636         */
 637        spin_lock_irqsave(&ms->lock, flags);
 638        if (!ms->failures.head)
 639                should_wake = 1;
 640        bio_list_add(&ms->failures, bio);
 641        spin_unlock_irqrestore(&ms->lock, flags);
 642        if (should_wake)
 643                wakeup_mirrord(ms);
 644}
 645
 646static void do_write(struct mirror_set *ms, struct bio *bio)
 647{
 648        unsigned int i;
 649        struct dm_io_region io[MAX_NR_MIRRORS], *dest = io;
 650        struct mirror *m;
 651        struct dm_io_request io_req = {
 652                .bi_op = REQ_OP_WRITE,
 653                .bi_op_flags = bio->bi_opf & (REQ_FUA | REQ_PREFLUSH),
 654                .mem.type = DM_IO_BIO,
 655                .mem.ptr.bio = bio,
 656                .notify.fn = write_callback,
 657                .notify.context = bio,
 658                .client = ms->io_client,
 659        };
 660
 661        if (bio_op(bio) == REQ_OP_DISCARD) {
 662                io_req.bi_op = REQ_OP_DISCARD;
 663                io_req.mem.type = DM_IO_KMEM;
 664                io_req.mem.ptr.addr = NULL;
 665        }
 666
 667        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
 668                map_region(dest++, m, bio);
 669
 670        /*
 671         * Use default mirror because we only need it to retrieve the reference
 672         * to the mirror set in write_callback().
 673         */
 674        bio_set_m(bio, get_default_mirror(ms));
 675
 676        BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL));
 677}
 678
 679static void do_writes(struct mirror_set *ms, struct bio_list *writes)
 680{
 681        int state;
 682        struct bio *bio;
 683        struct bio_list sync, nosync, recover, *this_list = NULL;
 684        struct bio_list requeue;
 685        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 686        region_t region;
 687
 688        if (!writes->head)
 689                return;
 690
 691        /*
 692         * Classify each write.
 693         */
 694        bio_list_init(&sync);
 695        bio_list_init(&nosync);
 696        bio_list_init(&recover);
 697        bio_list_init(&requeue);
 698
 699        while ((bio = bio_list_pop(writes))) {
 700                if ((bio->bi_opf & REQ_PREFLUSH) ||
 701                    (bio_op(bio) == REQ_OP_DISCARD)) {
 702                        bio_list_add(&sync, bio);
 703                        continue;
 704                }
 705
 706                region = dm_rh_bio_to_region(ms->rh, bio);
 707
 708                if (log->type->is_remote_recovering &&
 709                    log->type->is_remote_recovering(log, region)) {
 710                        bio_list_add(&requeue, bio);
 711                        continue;
 712                }
 713
 714                state = dm_rh_get_state(ms->rh, region, 1);
 715                switch (state) {
 716                case DM_RH_CLEAN:
 717                case DM_RH_DIRTY:
 718                        this_list = &sync;
 719                        break;
 720
 721                case DM_RH_NOSYNC:
 722                        this_list = &nosync;
 723                        break;
 724
 725                case DM_RH_RECOVERING:
 726                        this_list = &recover;
 727                        break;
 728                }
 729
 730                bio_list_add(this_list, bio);
 731        }
 732
 733        /*
 734         * Add bios that are delayed due to remote recovery
 735         * back on to the write queue
 736         */
 737        if (unlikely(requeue.head)) {
 738                spin_lock_irq(&ms->lock);
 739                bio_list_merge(&ms->writes, &requeue);
 740                spin_unlock_irq(&ms->lock);
 741                delayed_wake(ms);
 742        }
 743
 744        /*
 745         * Increment the pending counts for any regions that will
 746         * be written to (writes to recover regions are going to
 747         * be delayed).
 748         */
 749        dm_rh_inc_pending(ms->rh, &sync);
 750        dm_rh_inc_pending(ms->rh, &nosync);
 751
 752        /*
 753         * If the flush fails on a previous call and succeeds here,
 754         * we must not reset the log_failure variable.  We need
 755         * userspace interaction to do that.
 756         */
 757        ms->log_failure = dm_rh_flush(ms->rh) ? 1 : ms->log_failure;
 758
 759        /*
 760         * Dispatch io.
 761         */
 762        if (unlikely(ms->log_failure) && errors_handled(ms)) {
 763                spin_lock_irq(&ms->lock);
 764                bio_list_merge(&ms->failures, &sync);
 765                spin_unlock_irq(&ms->lock);
 766                wakeup_mirrord(ms);
 767        } else
 768                while ((bio = bio_list_pop(&sync)))
 769                        do_write(ms, bio);
 770
 771        while ((bio = bio_list_pop(&recover)))
 772                dm_rh_delay(ms->rh, bio);
 773
 774        while ((bio = bio_list_pop(&nosync))) {
 775                if (unlikely(ms->leg_failure) && errors_handled(ms) && !keep_log(ms)) {
 776                        spin_lock_irq(&ms->lock);
 777                        bio_list_add(&ms->failures, bio);
 778                        spin_unlock_irq(&ms->lock);
 779                        wakeup_mirrord(ms);
 780                } else {
 781                        map_bio(get_default_mirror(ms), bio);
 782                        submit_bio_noacct(bio);
 783                }
 784        }
 785}
 786
 787static void do_failures(struct mirror_set *ms, struct bio_list *failures)
 788{
 789        struct bio *bio;
 790
 791        if (likely(!failures->head))
 792                return;
 793
 794        /*
 795         * If the log has failed, unattempted writes are being
 796         * put on the holds list.  We can't issue those writes
 797         * until a log has been marked, so we must store them.
 798         *
 799         * If a 'noflush' suspend is in progress, we can requeue
 800         * the I/O's to the core.  This give userspace a chance
 801         * to reconfigure the mirror, at which point the core
 802         * will reissue the writes.  If the 'noflush' flag is
 803         * not set, we have no choice but to return errors.
 804         *
 805         * Some writes on the failures list may have been
 806         * submitted before the log failure and represent a
 807         * failure to write to one of the devices.  It is ok
 808         * for us to treat them the same and requeue them
 809         * as well.
 810         */
 811        while ((bio = bio_list_pop(failures))) {
 812                if (!ms->log_failure) {
 813                        ms->in_sync = 0;
 814                        dm_rh_mark_nosync(ms->rh, bio);
 815                }
 816
 817                /*
 818                 * If all the legs are dead, fail the I/O.
 819                 * If the device has failed and keep_log is enabled,
 820                 * fail the I/O.
 821                 *
 822                 * If we have been told to handle errors, and keep_log
 823                 * isn't enabled, hold the bio and wait for userspace to
 824                 * deal with the problem.
 825                 *
 826                 * Otherwise pretend that the I/O succeeded. (This would
 827                 * be wrong if the failed leg returned after reboot and
 828                 * got replicated back to the good legs.)
 829                 */
 830                if (unlikely(!get_valid_mirror(ms) || (keep_log(ms) && ms->log_failure)))
 831                        bio_io_error(bio);
 832                else if (errors_handled(ms) && !keep_log(ms))
 833                        hold_bio(ms, bio);
 834                else
 835                        bio_endio(bio);
 836        }
 837}
 838
 839static void trigger_event(struct work_struct *work)
 840{
 841        struct mirror_set *ms =
 842                container_of(work, struct mirror_set, trigger_event);
 843
 844        dm_table_event(ms->ti->table);
 845}
 846
 847/*-----------------------------------------------------------------
 848 * kmirrord
 849 *---------------------------------------------------------------*/
 850static void do_mirror(struct work_struct *work)
 851{
 852        struct mirror_set *ms = container_of(work, struct mirror_set,
 853                                             kmirrord_work);
 854        struct bio_list reads, writes, failures;
 855        unsigned long flags;
 856
 857        spin_lock_irqsave(&ms->lock, flags);
 858        reads = ms->reads;
 859        writes = ms->writes;
 860        failures = ms->failures;
 861        bio_list_init(&ms->reads);
 862        bio_list_init(&ms->writes);
 863        bio_list_init(&ms->failures);
 864        spin_unlock_irqrestore(&ms->lock, flags);
 865
 866        dm_rh_update_states(ms->rh, errors_handled(ms));
 867        do_recovery(ms);
 868        do_reads(ms, &reads);
 869        do_writes(ms, &writes);
 870        do_failures(ms, &failures);
 871}
 872
 873/*-----------------------------------------------------------------
 874 * Target functions
 875 *---------------------------------------------------------------*/
 876static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 877                                        uint32_t region_size,
 878                                        struct dm_target *ti,
 879                                        struct dm_dirty_log *dl)
 880{
 881        struct mirror_set *ms =
 882                kzalloc(struct_size(ms, mirror, nr_mirrors), GFP_KERNEL);
 883
 884        if (!ms) {
 885                ti->error = "Cannot allocate mirror context";
 886                return NULL;
 887        }
 888
 889        spin_lock_init(&ms->lock);
 890        bio_list_init(&ms->reads);
 891        bio_list_init(&ms->writes);
 892        bio_list_init(&ms->failures);
 893        bio_list_init(&ms->holds);
 894
 895        ms->ti = ti;
 896        ms->nr_mirrors = nr_mirrors;
 897        ms->nr_regions = dm_sector_div_up(ti->len, region_size);
 898        ms->in_sync = 0;
 899        ms->log_failure = 0;
 900        ms->leg_failure = 0;
 901        atomic_set(&ms->suspend, 0);
 902        atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
 903
 904        ms->io_client = dm_io_client_create();
 905        if (IS_ERR(ms->io_client)) {
 906                ti->error = "Error creating dm_io client";
 907                kfree(ms);
 908                return NULL;
 909        }
 910
 911        ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord,
 912                                       wakeup_all_recovery_waiters,
 913                                       ms->ti->begin, MAX_RECOVERY,
 914                                       dl, region_size, ms->nr_regions);
 915        if (IS_ERR(ms->rh)) {
 916                ti->error = "Error creating dirty region hash";
 917                dm_io_client_destroy(ms->io_client);
 918                kfree(ms);
 919                return NULL;
 920        }
 921
 922        return ms;
 923}
 924
 925static void free_context(struct mirror_set *ms, struct dm_target *ti,
 926                         unsigned int m)
 927{
 928        while (m--)
 929                dm_put_device(ti, ms->mirror[m].dev);
 930
 931        dm_io_client_destroy(ms->io_client);
 932        dm_region_hash_destroy(ms->rh);
 933        kfree(ms);
 934}
 935
 936static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
 937                      unsigned int mirror, char **argv)
 938{
 939        unsigned long long offset;
 940        char dummy;
 941        int ret;
 942
 943        if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1 ||
 944            offset != (sector_t)offset) {
 945                ti->error = "Invalid offset";
 946                return -EINVAL;
 947        }
 948
 949        ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
 950                            &ms->mirror[mirror].dev);
 951        if (ret) {
 952                ti->error = "Device lookup failure";
 953                return ret;
 954        }
 955
 956        ms->mirror[mirror].ms = ms;
 957        atomic_set(&(ms->mirror[mirror].error_count), 0);
 958        ms->mirror[mirror].error_type = 0;
 959        ms->mirror[mirror].offset = offset;
 960
 961        return 0;
 962}
 963
 964/*
 965 * Create dirty log: log_type #log_params <log_params>
 966 */
 967static struct dm_dirty_log *create_dirty_log(struct dm_target *ti,
 968                                             unsigned argc, char **argv,
 969                                             unsigned *args_used)
 970{
 971        unsigned param_count;
 972        struct dm_dirty_log *dl;
 973        char dummy;
 974
 975        if (argc < 2) {
 976                ti->error = "Insufficient mirror log arguments";
 977                return NULL;
 978        }
 979
 980        if (sscanf(argv[1], "%u%c", &param_count, &dummy) != 1) {
 981                ti->error = "Invalid mirror log argument count";
 982                return NULL;
 983        }
 984
 985        *args_used = 2 + param_count;
 986
 987        if (argc < *args_used) {
 988                ti->error = "Insufficient mirror log arguments";
 989                return NULL;
 990        }
 991
 992        dl = dm_dirty_log_create(argv[0], ti, mirror_flush, param_count,
 993                                 argv + 2);
 994        if (!dl) {
 995                ti->error = "Error creating mirror dirty log";
 996                return NULL;
 997        }
 998
 999        return dl;
1000}
1001
1002static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
1003                          unsigned *args_used)
1004{
1005        unsigned num_features;
1006        struct dm_target *ti = ms->ti;
1007        char dummy;
1008        int i;
1009
1010        *args_used = 0;
1011
1012        if (!argc)
1013                return 0;
1014
1015        if (sscanf(argv[0], "%u%c", &num_features, &dummy) != 1) {
1016                ti->error = "Invalid number of features";
1017                return -EINVAL;
1018        }
1019
1020        argc--;
1021        argv++;
1022        (*args_used)++;
1023
1024        if (num_features > argc) {
1025                ti->error = "Not enough arguments to support feature count";
1026                return -EINVAL;
1027        }
1028
1029        for (i = 0; i < num_features; i++) {
1030                if (!strcmp("handle_errors", argv[0]))
1031                        ms->features |= DM_RAID1_HANDLE_ERRORS;
1032                else if (!strcmp("keep_log", argv[0]))
1033                        ms->features |= DM_RAID1_KEEP_LOG;
1034                else {
1035                        ti->error = "Unrecognised feature requested";
1036                        return -EINVAL;
1037                }
1038
1039                argc--;
1040                argv++;
1041                (*args_used)++;
1042        }
1043        if (!errors_handled(ms) && keep_log(ms)) {
1044                ti->error = "keep_log feature requires the handle_errors feature";
1045                return -EINVAL;
1046        }
1047
1048        return 0;
1049}
1050
1051/*
1052 * Construct a mirror mapping:
1053 *
1054 * log_type #log_params <log_params>
1055 * #mirrors [mirror_path offset]{2,}
1056 * [#features <features>]
1057 *
1058 * log_type is "core" or "disk"
1059 * #log_params is between 1 and 3
1060 *
1061 * If present, supported features are "handle_errors" and "keep_log".
1062 */
1063static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1064{
1065        int r;
1066        unsigned int nr_mirrors, m, args_used;
1067        struct mirror_set *ms;
1068        struct dm_dirty_log *dl;
1069        char dummy;
1070
1071        dl = create_dirty_log(ti, argc, argv, &args_used);
1072        if (!dl)
1073                return -EINVAL;
1074
1075        argv += args_used;
1076        argc -= args_used;
1077
1078        if (!argc || sscanf(argv[0], "%u%c", &nr_mirrors, &dummy) != 1 ||
1079            nr_mirrors < 2 || nr_mirrors > MAX_NR_MIRRORS) {
1080                ti->error = "Invalid number of mirrors";
1081                dm_dirty_log_destroy(dl);
1082                return -EINVAL;
1083        }
1084
1085        argv++, argc--;
1086
1087        if (argc < nr_mirrors * 2) {
1088                ti->error = "Too few mirror arguments";
1089                dm_dirty_log_destroy(dl);
1090                return -EINVAL;
1091        }
1092
1093        ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
1094        if (!ms) {
1095                dm_dirty_log_destroy(dl);
1096                return -ENOMEM;
1097        }
1098
1099        /* Get the mirror parameter sets */
1100        for (m = 0; m < nr_mirrors; m++) {
1101                r = get_mirror(ms, ti, m, argv);
1102                if (r) {
1103                        free_context(ms, ti, m);
1104                        return r;
1105                }
1106                argv += 2;
1107                argc -= 2;
1108        }
1109
1110        ti->private = ms;
1111
1112        r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
1113        if (r)
1114                goto err_free_context;
1115
1116        ti->num_flush_bios = 1;
1117        ti->num_discard_bios = 1;
1118        ti->per_io_data_size = sizeof(struct dm_raid1_bio_record);
1119
1120        ms->kmirrord_wq = alloc_workqueue("kmirrord", WQ_MEM_RECLAIM, 0);
1121        if (!ms->kmirrord_wq) {
1122                DMERR("couldn't start kmirrord");
1123                r = -ENOMEM;
1124                goto err_free_context;
1125        }
1126        INIT_WORK(&ms->kmirrord_work, do_mirror);
1127        timer_setup(&ms->timer, delayed_wake_fn, 0);
1128        ms->timer_pending = 0;
1129        INIT_WORK(&ms->trigger_event, trigger_event);
1130
1131        r = parse_features(ms, argc, argv, &args_used);
1132        if (r)
1133                goto err_destroy_wq;
1134
1135        argv += args_used;
1136        argc -= args_used;
1137
1138        /*
1139         * Any read-balancing addition depends on the
1140         * DM_RAID1_HANDLE_ERRORS flag being present.
1141         * This is because the decision to balance depends
1142         * on the sync state of a region.  If the above
1143         * flag is not present, we ignore errors; and
1144         * the sync state may be inaccurate.
1145         */
1146
1147        if (argc) {
1148                ti->error = "Too many mirror arguments";
1149                r = -EINVAL;
1150                goto err_destroy_wq;
1151        }
1152
1153        ms->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
1154        if (IS_ERR(ms->kcopyd_client)) {
1155                r = PTR_ERR(ms->kcopyd_client);
1156                goto err_destroy_wq;
1157        }
1158
1159        wakeup_mirrord(ms);
1160        return 0;
1161
1162err_destroy_wq:
1163        destroy_workqueue(ms->kmirrord_wq);
1164err_free_context:
1165        free_context(ms, ti, ms->nr_mirrors);
1166        return r;
1167}
1168
1169static void mirror_dtr(struct dm_target *ti)
1170{
1171        struct mirror_set *ms = (struct mirror_set *) ti->private;
1172
1173        del_timer_sync(&ms->timer);
1174        flush_workqueue(ms->kmirrord_wq);
1175        flush_work(&ms->trigger_event);
1176        dm_kcopyd_client_destroy(ms->kcopyd_client);
1177        destroy_workqueue(ms->kmirrord_wq);
1178        free_context(ms, ti, ms->nr_mirrors);
1179}
1180
1181/*
1182 * Mirror mapping function
1183 */
1184static int mirror_map(struct dm_target *ti, struct bio *bio)
1185{
1186        int r, rw = bio_data_dir(bio);
1187        struct mirror *m;
1188        struct mirror_set *ms = ti->private;
1189        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1190        struct dm_raid1_bio_record *bio_record =
1191          dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
1192
1193        bio_record->details.bi_bdev = NULL;
1194
1195        if (rw == WRITE) {
1196                /* Save region for mirror_end_io() handler */
1197                bio_record->write_region = dm_rh_bio_to_region(ms->rh, bio);
1198                queue_bio(ms, bio, rw);
1199                return DM_MAPIO_SUBMITTED;
1200        }
1201
1202        r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
1203        if (r < 0 && r != -EWOULDBLOCK)
1204                return DM_MAPIO_KILL;
1205
1206        /*
1207         * If region is not in-sync queue the bio.
1208         */
1209        if (!r || (r == -EWOULDBLOCK)) {
1210                if (bio->bi_opf & REQ_RAHEAD)
1211                        return DM_MAPIO_KILL;
1212
1213                queue_bio(ms, bio, rw);
1214                return DM_MAPIO_SUBMITTED;
1215        }
1216
1217        /*
1218         * The region is in-sync and we can perform reads directly.
1219         * Store enough information so we can retry if it fails.
1220         */
1221        m = choose_mirror(ms, bio->bi_iter.bi_sector);
1222        if (unlikely(!m))
1223                return DM_MAPIO_KILL;
1224
1225        dm_bio_record(&bio_record->details, bio);
1226        bio_record->m = m;
1227
1228        map_bio(m, bio);
1229
1230        return DM_MAPIO_REMAPPED;
1231}
1232
1233static int mirror_end_io(struct dm_target *ti, struct bio *bio,
1234                blk_status_t *error)
1235{
1236        int rw = bio_data_dir(bio);
1237        struct mirror_set *ms = (struct mirror_set *) ti->private;
1238        struct mirror *m = NULL;
1239        struct dm_bio_details *bd = NULL;
1240        struct dm_raid1_bio_record *bio_record =
1241          dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
1242
1243        /*
1244         * We need to dec pending if this was a write.
1245         */
1246        if (rw == WRITE) {
1247                if (!(bio->bi_opf & REQ_PREFLUSH) &&
1248                    bio_op(bio) != REQ_OP_DISCARD)
1249                        dm_rh_dec(ms->rh, bio_record->write_region);
1250                return DM_ENDIO_DONE;
1251        }
1252
1253        if (*error == BLK_STS_NOTSUPP)
1254                goto out;
1255
1256        if (bio->bi_opf & REQ_RAHEAD)
1257                goto out;
1258
1259        if (unlikely(*error)) {
1260                if (!bio_record->details.bi_bdev) {
1261                        /*
1262                         * There wasn't enough memory to record necessary
1263                         * information for a retry or there was no other
1264                         * mirror in-sync.
1265                         */
1266                        DMERR_LIMIT("Mirror read failed.");
1267                        return DM_ENDIO_DONE;
1268                }
1269
1270                m = bio_record->m;
1271
1272                DMERR("Mirror read failed from %s. Trying alternative device.",
1273                      m->dev->name);
1274
1275                fail_mirror(m, DM_RAID1_READ_ERROR);
1276
1277                /*
1278                 * A failed read is requeued for another attempt using an intact
1279                 * mirror.
1280                 */
1281                if (default_ok(m) || mirror_available(ms, bio)) {
1282                        bd = &bio_record->details;
1283
1284                        dm_bio_restore(bd, bio);
1285                        bio_record->details.bi_bdev = NULL;
1286                        bio->bi_status = 0;
1287
1288                        queue_bio(ms, bio, rw);
1289                        return DM_ENDIO_INCOMPLETE;
1290                }
1291                DMERR("All replicated volumes dead, failing I/O");
1292        }
1293
1294out:
1295        bio_record->details.bi_bdev = NULL;
1296
1297        return DM_ENDIO_DONE;
1298}
1299
1300static void mirror_presuspend(struct dm_target *ti)
1301{
1302        struct mirror_set *ms = (struct mirror_set *) ti->private;
1303        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1304
1305        struct bio_list holds;
1306        struct bio *bio;
1307
1308        atomic_set(&ms->suspend, 1);
1309
1310        /*
1311         * Process bios in the hold list to start recovery waiting
1312         * for bios in the hold list. After the process, no bio has
1313         * a chance to be added in the hold list because ms->suspend
1314         * is set.
1315         */
1316        spin_lock_irq(&ms->lock);
1317        holds = ms->holds;
1318        bio_list_init(&ms->holds);
1319        spin_unlock_irq(&ms->lock);
1320
1321        while ((bio = bio_list_pop(&holds)))
1322                hold_bio(ms, bio);
1323
1324        /*
1325         * We must finish up all the work that we've
1326         * generated (i.e. recovery work).
1327         */
1328        dm_rh_stop_recovery(ms->rh);
1329
1330        wait_event(_kmirrord_recovery_stopped,
1331                   !dm_rh_recovery_in_flight(ms->rh));
1332
1333        if (log->type->presuspend && log->type->presuspend(log))
1334                /* FIXME: need better error handling */
1335                DMWARN("log presuspend failed");
1336
1337        /*
1338         * Now that recovery is complete/stopped and the
1339         * delayed bios are queued, we need to wait for
1340         * the worker thread to complete.  This way,
1341         * we know that all of our I/O has been pushed.
1342         */
1343        flush_workqueue(ms->kmirrord_wq);
1344}
1345
1346static void mirror_postsuspend(struct dm_target *ti)
1347{
1348        struct mirror_set *ms = ti->private;
1349        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1350
1351        if (log->type->postsuspend && log->type->postsuspend(log))
1352                /* FIXME: need better error handling */
1353                DMWARN("log postsuspend failed");
1354}
1355
1356static void mirror_resume(struct dm_target *ti)
1357{
1358        struct mirror_set *ms = ti->private;
1359        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1360
1361        atomic_set(&ms->suspend, 0);
1362        if (log->type->resume && log->type->resume(log))
1363                /* FIXME: need better error handling */
1364                DMWARN("log resume failed");
1365        dm_rh_start_recovery(ms->rh);
1366}
1367
1368/*
1369 * device_status_char
1370 * @m: mirror device/leg we want the status of
1371 *
1372 * We return one character representing the most severe error
1373 * we have encountered.
1374 *    A => Alive - No failures
1375 *    D => Dead - A write failure occurred leaving mirror out-of-sync
1376 *    S => Sync - A sychronization failure occurred, mirror out-of-sync
1377 *    R => Read - A read failure occurred, mirror data unaffected
1378 *
1379 * Returns: <char>
1380 */
1381static char device_status_char(struct mirror *m)
1382{
1383        if (!atomic_read(&(m->error_count)))
1384                return 'A';
1385
1386        return (test_bit(DM_RAID1_FLUSH_ERROR, &(m->error_type))) ? 'F' :
1387                (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' :
1388                (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' :
1389                (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
1390}
1391
1392
1393static void mirror_status(struct dm_target *ti, status_type_t type,
1394                          unsigned status_flags, char *result, unsigned maxlen)
1395{
1396        unsigned int m, sz = 0;
1397        int num_feature_args = 0;
1398        struct mirror_set *ms = (struct mirror_set *) ti->private;
1399        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1400        char buffer[MAX_NR_MIRRORS + 1];
1401
1402        switch (type) {
1403        case STATUSTYPE_INFO:
1404                DMEMIT("%d ", ms->nr_mirrors);
1405                for (m = 0; m < ms->nr_mirrors; m++) {
1406                        DMEMIT("%s ", ms->mirror[m].dev->name);
1407                        buffer[m] = device_status_char(&(ms->mirror[m]));
1408                }
1409                buffer[m] = '\0';
1410
1411                DMEMIT("%llu/%llu 1 %s ",
1412                      (unsigned long long)log->type->get_sync_count(log),
1413                      (unsigned long long)ms->nr_regions, buffer);
1414
1415                sz += log->type->status(log, type, result+sz, maxlen-sz);
1416
1417                break;
1418
1419        case STATUSTYPE_TABLE:
1420                sz = log->type->status(log, type, result, maxlen);
1421
1422                DMEMIT("%d", ms->nr_mirrors);
1423                for (m = 0; m < ms->nr_mirrors; m++)
1424                        DMEMIT(" %s %llu", ms->mirror[m].dev->name,
1425                               (unsigned long long)ms->mirror[m].offset);
1426
1427                num_feature_args += !!errors_handled(ms);
1428                num_feature_args += !!keep_log(ms);
1429                if (num_feature_args) {
1430                        DMEMIT(" %d", num_feature_args);
1431                        if (errors_handled(ms))
1432                                DMEMIT(" handle_errors");
1433                        if (keep_log(ms))
1434                                DMEMIT(" keep_log");
1435                }
1436
1437                break;
1438        }
1439}
1440
1441static int mirror_iterate_devices(struct dm_target *ti,
1442                                  iterate_devices_callout_fn fn, void *data)
1443{
1444        struct mirror_set *ms = ti->private;
1445        int ret = 0;
1446        unsigned i;
1447
1448        for (i = 0; !ret && i < ms->nr_mirrors; i++)
1449                ret = fn(ti, ms->mirror[i].dev,
1450                         ms->mirror[i].offset, ti->len, data);
1451
1452        return ret;
1453}
1454
1455static struct target_type mirror_target = {
1456        .name    = "mirror",
1457        .version = {1, 14, 0},
1458        .module  = THIS_MODULE,
1459        .ctr     = mirror_ctr,
1460        .dtr     = mirror_dtr,
1461        .map     = mirror_map,
1462        .end_io  = mirror_end_io,
1463        .presuspend = mirror_presuspend,
1464        .postsuspend = mirror_postsuspend,
1465        .resume  = mirror_resume,
1466        .status  = mirror_status,
1467        .iterate_devices = mirror_iterate_devices,
1468};
1469
1470static int __init dm_mirror_init(void)
1471{
1472        int r;
1473
1474        r = dm_register_target(&mirror_target);
1475        if (r < 0) {
1476                DMERR("Failed to register mirror target");
1477                goto bad_target;
1478        }
1479
1480        return 0;
1481
1482bad_target:
1483        return r;
1484}
1485
1486static void __exit dm_mirror_exit(void)
1487{
1488        dm_unregister_target(&mirror_target);
1489}
1490
1491/* Module hooks */
1492module_init(dm_mirror_init);
1493module_exit(dm_mirror_exit);
1494
1495MODULE_DESCRIPTION(DM_NAME " mirror target");
1496MODULE_AUTHOR("Joe Thornber");
1497MODULE_LICENSE("GPL");
1498