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
  65        /* recovery */
  66        region_t nr_regions;
  67        int in_sync;
  68        int log_failure;
  69        int leg_failure;
  70        atomic_t suspend;
  71
  72        atomic_t default_mirror;        /* Default mirror */
  73
  74        struct workqueue_struct *kmirrord_wq;
  75        struct work_struct kmirrord_work;
  76        struct timer_list timer;
  77        unsigned long timer_pending;
  78
  79        struct work_struct trigger_event;
  80
  81        unsigned nr_mirrors;
  82        struct mirror mirror[0];
  83};
  84
  85DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle,
  86                "A percentage of time allocated for raid resynchronization");
  87
  88static void wakeup_mirrord(void *context)
  89{
  90        struct mirror_set *ms = context;
  91
  92        queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
  93}
  94
  95static void delayed_wake_fn(unsigned long data)
  96{
  97        struct mirror_set *ms = (struct mirror_set *) data;
  98
  99        clear_bit(0, &ms->timer_pending);
 100        wakeup_mirrord(ms);
 101}
 102
 103static void delayed_wake(struct mirror_set *ms)
 104{
 105        if (test_and_set_bit(0, &ms->timer_pending))
 106                return;
 107
 108        ms->timer.expires = jiffies + HZ / 5;
 109        ms->timer.data = (unsigned long) ms;
 110        ms->timer.function = delayed_wake_fn;
 111        add_timer(&ms->timer);
 112}
 113
 114static void wakeup_all_recovery_waiters(void *context)
 115{
 116        wake_up_all(&_kmirrord_recovery_stopped);
 117}
 118
 119static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
 120{
 121        unsigned long flags;
 122        int should_wake = 0;
 123        struct bio_list *bl;
 124
 125        bl = (rw == WRITE) ? &ms->writes : &ms->reads;
 126        spin_lock_irqsave(&ms->lock, flags);
 127        should_wake = !(bl->head);
 128        bio_list_add(bl, bio);
 129        spin_unlock_irqrestore(&ms->lock, flags);
 130
 131        if (should_wake)
 132                wakeup_mirrord(ms);
 133}
 134
 135static void dispatch_bios(void *context, struct bio_list *bio_list)
 136{
 137        struct mirror_set *ms = context;
 138        struct bio *bio;
 139
 140        while ((bio = bio_list_pop(bio_list)))
 141                queue_bio(ms, bio, WRITE);
 142}
 143
 144struct dm_raid1_bio_record {
 145        struct mirror *m;
 146        /* if details->bi_bdev == NULL, details were not saved */
 147        struct dm_bio_details details;
 148        region_t write_region;
 149};
 150
 151/*
 152 * Every mirror should look like this one.
 153 */
 154#define DEFAULT_MIRROR 0
 155
 156/*
 157 * This is yucky.  We squirrel the mirror struct away inside
 158 * bi_next for read/write buffers.  This is safe since the bh
 159 * doesn't get submitted to the lower levels of block layer.
 160 */
 161static struct mirror *bio_get_m(struct bio *bio)
 162{
 163        return (struct mirror *) bio->bi_next;
 164}
 165
 166static void bio_set_m(struct bio *bio, struct mirror *m)
 167{
 168        bio->bi_next = (struct bio *) m;
 169}
 170
 171static struct mirror *get_default_mirror(struct mirror_set *ms)
 172{
 173        return &ms->mirror[atomic_read(&ms->default_mirror)];
 174}
 175
 176static void set_default_mirror(struct mirror *m)
 177{
 178        struct mirror_set *ms = m->ms;
 179        struct mirror *m0 = &(ms->mirror[0]);
 180
 181        atomic_set(&ms->default_mirror, m - m0);
 182}
 183
 184static struct mirror *get_valid_mirror(struct mirror_set *ms)
 185{
 186        struct mirror *m;
 187
 188        for (m = ms->mirror; m < ms->mirror + ms->nr_mirrors; m++)
 189                if (!atomic_read(&m->error_count))
 190                        return m;
 191
 192        return NULL;
 193}
 194
 195/* fail_mirror
 196 * @m: mirror device to fail
 197 * @error_type: one of the enum's, DM_RAID1_*_ERROR
 198 *
 199 * If errors are being handled, record the type of
 200 * error encountered for this device.  If this type
 201 * of error has already been recorded, we can return;
 202 * otherwise, we must signal userspace by triggering
 203 * an event.  Additionally, if the device is the
 204 * primary device, we must choose a new primary, but
 205 * only if the mirror is in-sync.
 206 *
 207 * This function must not block.
 208 */
 209static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
 210{
 211        struct mirror_set *ms = m->ms;
 212        struct mirror *new;
 213
 214        ms->leg_failure = 1;
 215
 216        /*
 217         * error_count is used for nothing more than a
 218         * simple way to tell if a device has encountered
 219         * errors.
 220         */
 221        atomic_inc(&m->error_count);
 222
 223        if (test_and_set_bit(error_type, &m->error_type))
 224                return;
 225
 226        if (!errors_handled(ms))
 227                return;
 228
 229        if (m != get_default_mirror(ms))
 230                goto out;
 231
 232        if (!ms->in_sync) {
 233                /*
 234                 * Better to issue requests to same failing device
 235                 * than to risk returning corrupt data.
 236                 */
 237                DMERR("Primary mirror (%s) failed while out-of-sync: "
 238                      "Reads may fail.", m->dev->name);
 239                goto out;
 240        }
 241
 242        new = get_valid_mirror(ms);
 243        if (new)
 244                set_default_mirror(new);
 245        else
 246                DMWARN("All sides of mirror have failed.");
 247
 248out:
 249        schedule_work(&ms->trigger_event);
 250}
 251
 252static int mirror_flush(struct dm_target *ti)
 253{
 254        struct mirror_set *ms = ti->private;
 255        unsigned long error_bits;
 256
 257        unsigned int i;
 258        struct dm_io_region io[ms->nr_mirrors];
 259        struct mirror *m;
 260        struct dm_io_request io_req = {
 261                .bi_rw = WRITE_FLUSH,
 262                .mem.type = DM_IO_KMEM,
 263                .mem.ptr.addr = NULL,
 264                .client = ms->io_client,
 265        };
 266
 267        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
 268                io[i].bdev = m->dev->bdev;
 269                io[i].sector = 0;
 270                io[i].count = 0;
 271        }
 272
 273        error_bits = -1;
 274        dm_io(&io_req, ms->nr_mirrors, io, &error_bits);
 275        if (unlikely(error_bits != 0)) {
 276                for (i = 0; i < ms->nr_mirrors; i++)
 277                        if (test_bit(i, &error_bits))
 278                                fail_mirror(ms->mirror + i,
 279                                            DM_RAID1_FLUSH_ERROR);
 280                return -EIO;
 281        }
 282
 283        return 0;
 284}
 285
 286/*-----------------------------------------------------------------
 287 * Recovery.
 288 *
 289 * When a mirror is first activated we may find that some regions
 290 * are in the no-sync state.  We have to recover these by
 291 * recopying from the default mirror to all the others.
 292 *---------------------------------------------------------------*/
 293static void recovery_complete(int read_err, unsigned long write_err,
 294                              void *context)
 295{
 296        struct dm_region *reg = context;
 297        struct mirror_set *ms = dm_rh_region_context(reg);
 298        int m, bit = 0;
 299
 300        if (read_err) {
 301                /* Read error means the failure of default mirror. */
 302                DMERR_LIMIT("Unable to read primary mirror during recovery");
 303                fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR);
 304        }
 305
 306        if (write_err) {
 307                DMERR_LIMIT("Write error during recovery (error = 0x%lx)",
 308                            write_err);
 309                /*
 310                 * Bits correspond to devices (excluding default mirror).
 311                 * The default mirror cannot change during recovery.
 312                 */
 313                for (m = 0; m < ms->nr_mirrors; m++) {
 314                        if (&ms->mirror[m] == get_default_mirror(ms))
 315                                continue;
 316                        if (test_bit(bit, &write_err))
 317                                fail_mirror(ms->mirror + m,
 318                                            DM_RAID1_SYNC_ERROR);
 319                        bit++;
 320                }
 321        }
 322
 323        dm_rh_recovery_end(reg, !(read_err || write_err));
 324}
 325
 326static int recover(struct mirror_set *ms, struct dm_region *reg)
 327{
 328        int r;
 329        unsigned i;
 330        struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest;
 331        struct mirror *m;
 332        unsigned long flags = 0;
 333        region_t key = dm_rh_get_region_key(reg);
 334        sector_t region_size = dm_rh_get_region_size(ms->rh);
 335
 336        /* fill in the source */
 337        m = get_default_mirror(ms);
 338        from.bdev = m->dev->bdev;
 339        from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
 340        if (key == (ms->nr_regions - 1)) {
 341                /*
 342                 * The final region may be smaller than
 343                 * region_size.
 344                 */
 345                from.count = ms->ti->len & (region_size - 1);
 346                if (!from.count)
 347                        from.count = region_size;
 348        } else
 349                from.count = region_size;
 350
 351        /* fill in the destinations */
 352        for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
 353                if (&ms->mirror[i] == get_default_mirror(ms))
 354                        continue;
 355
 356                m = ms->mirror + i;
 357                dest->bdev = m->dev->bdev;
 358                dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
 359                dest->count = from.count;
 360                dest++;
 361        }
 362
 363        /* hand to kcopyd */
 364        if (!errors_handled(ms))
 365                set_bit(DM_KCOPYD_IGNORE_ERROR, &flags);
 366
 367        r = dm_kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to,
 368                           flags, recovery_complete, reg);
 369
 370        return r;
 371}
 372
 373static void do_recovery(struct mirror_set *ms)
 374{
 375        struct dm_region *reg;
 376        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 377        int r;
 378
 379        /*
 380         * Start quiescing some regions.
 381         */
 382        dm_rh_recovery_prepare(ms->rh);
 383
 384        /*
 385         * Copy any already quiesced regions.
 386         */
 387        while ((reg = dm_rh_recovery_start(ms->rh))) {
 388                r = recover(ms, reg);
 389                if (r)
 390                        dm_rh_recovery_end(reg, 0);
 391        }
 392
 393        /*
 394         * Update the in sync flag.
 395         */
 396        if (!ms->in_sync &&
 397            (log->type->get_sync_count(log) == ms->nr_regions)) {
 398                /* the sync is complete */
 399                dm_table_event(ms->ti->table);
 400                ms->in_sync = 1;
 401        }
 402}
 403
 404/*-----------------------------------------------------------------
 405 * Reads
 406 *---------------------------------------------------------------*/
 407static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
 408{
 409        struct mirror *m = get_default_mirror(ms);
 410
 411        do {
 412                if (likely(!atomic_read(&m->error_count)))
 413                        return m;
 414
 415                if (m-- == ms->mirror)
 416                        m += ms->nr_mirrors;
 417        } while (m != get_default_mirror(ms));
 418
 419        return NULL;
 420}
 421
 422static int default_ok(struct mirror *m)
 423{
 424        struct mirror *default_mirror = get_default_mirror(m->ms);
 425
 426        return !atomic_read(&default_mirror->error_count);
 427}
 428
 429static int mirror_available(struct mirror_set *ms, struct bio *bio)
 430{
 431        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 432        region_t region = dm_rh_bio_to_region(ms->rh, bio);
 433
 434        if (log->type->in_sync(log, region, 0))
 435                return choose_mirror(ms,  bio->bi_sector) ? 1 : 0;
 436
 437        return 0;
 438}
 439
 440/*
 441 * remap a buffer to a particular mirror.
 442 */
 443static sector_t map_sector(struct mirror *m, struct bio *bio)
 444{
 445        if (unlikely(!bio->bi_size))
 446                return 0;
 447        return m->offset + dm_target_offset(m->ms->ti, bio->bi_sector);
 448}
 449
 450static void map_bio(struct mirror *m, struct bio *bio)
 451{
 452        bio->bi_bdev = m->dev->bdev;
 453        bio->bi_sector = map_sector(m, bio);
 454}
 455
 456static void map_region(struct dm_io_region *io, struct mirror *m,
 457                       struct bio *bio)
 458{
 459        io->bdev = m->dev->bdev;
 460        io->sector = map_sector(m, bio);
 461        io->count = bio_sectors(bio);
 462}
 463
 464static void hold_bio(struct mirror_set *ms, struct bio *bio)
 465{
 466        /*
 467         * Lock is required to avoid race condition during suspend
 468         * process.
 469         */
 470        spin_lock_irq(&ms->lock);
 471
 472        if (atomic_read(&ms->suspend)) {
 473                spin_unlock_irq(&ms->lock);
 474
 475                /*
 476                 * If device is suspended, complete the bio.
 477                 */
 478                if (dm_noflush_suspending(ms->ti))
 479                        bio_endio(bio, DM_ENDIO_REQUEUE);
 480                else
 481                        bio_endio(bio, -EIO);
 482                return;
 483        }
 484
 485        /*
 486         * Hold bio until the suspend is complete.
 487         */
 488        bio_list_add(&ms->holds, bio);
 489        spin_unlock_irq(&ms->lock);
 490}
 491
 492/*-----------------------------------------------------------------
 493 * Reads
 494 *---------------------------------------------------------------*/
 495static void read_callback(unsigned long error, void *context)
 496{
 497        struct bio *bio = context;
 498        struct mirror *m;
 499
 500        m = bio_get_m(bio);
 501        bio_set_m(bio, NULL);
 502
 503        if (likely(!error)) {
 504                bio_endio(bio, 0);
 505                return;
 506        }
 507
 508        fail_mirror(m, DM_RAID1_READ_ERROR);
 509
 510        if (likely(default_ok(m)) || mirror_available(m->ms, bio)) {
 511                DMWARN_LIMIT("Read failure on mirror device %s.  "
 512                             "Trying alternative device.",
 513                             m->dev->name);
 514                queue_bio(m->ms, bio, bio_rw(bio));
 515                return;
 516        }
 517
 518        DMERR_LIMIT("Read failure on mirror device %s.  Failing I/O.",
 519                    m->dev->name);
 520        bio_endio(bio, -EIO);
 521}
 522
 523/* Asynchronous read. */
 524static void read_async_bio(struct mirror *m, struct bio *bio)
 525{
 526        struct dm_io_region io;
 527        struct dm_io_request io_req = {
 528                .bi_rw = READ,
 529                .mem.type = DM_IO_BVEC,
 530                .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
 531                .notify.fn = read_callback,
 532                .notify.context = bio,
 533                .client = m->ms->io_client,
 534        };
 535
 536        map_region(&io, m, bio);
 537        bio_set_m(bio, m);
 538        BUG_ON(dm_io(&io_req, 1, &io, NULL));
 539}
 540
 541static inline int region_in_sync(struct mirror_set *ms, region_t region,
 542                                 int may_block)
 543{
 544        int state = dm_rh_get_state(ms->rh, region, may_block);
 545        return state == DM_RH_CLEAN || state == DM_RH_DIRTY;
 546}
 547
 548static void do_reads(struct mirror_set *ms, struct bio_list *reads)
 549{
 550        region_t region;
 551        struct bio *bio;
 552        struct mirror *m;
 553
 554        while ((bio = bio_list_pop(reads))) {
 555                region = dm_rh_bio_to_region(ms->rh, bio);
 556                m = get_default_mirror(ms);
 557
 558                /*
 559                 * We can only read balance if the region is in sync.
 560                 */
 561                if (likely(region_in_sync(ms, region, 1)))
 562                        m = choose_mirror(ms, bio->bi_sector);
 563                else if (m && atomic_read(&m->error_count))
 564                        m = NULL;
 565
 566                if (likely(m))
 567                        read_async_bio(m, bio);
 568                else
 569                        bio_endio(bio, -EIO);
 570        }
 571}
 572
 573/*-----------------------------------------------------------------
 574 * Writes.
 575 *
 576 * We do different things with the write io depending on the
 577 * state of the region that it's in:
 578 *
 579 * SYNC:        increment pending, use kcopyd to write to *all* mirrors
 580 * RECOVERING:  delay the io until recovery completes
 581 * NOSYNC:      increment pending, just write to the default mirror
 582 *---------------------------------------------------------------*/
 583
 584
 585static void write_callback(unsigned long error, void *context)
 586{
 587        unsigned i, ret = 0;
 588        struct bio *bio = (struct bio *) context;
 589        struct mirror_set *ms;
 590        int should_wake = 0;
 591        unsigned long flags;
 592
 593        ms = bio_get_m(bio)->ms;
 594        bio_set_m(bio, NULL);
 595
 596        /*
 597         * NOTE: We don't decrement the pending count here,
 598         * instead it is done by the targets endio function.
 599         * This way we handle both writes to SYNC and NOSYNC
 600         * regions with the same code.
 601         */
 602        if (likely(!error)) {
 603                bio_endio(bio, ret);
 604                return;
 605        }
 606
 607        for (i = 0; i < ms->nr_mirrors; i++)
 608                if (test_bit(i, &error))
 609                        fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
 610
 611        /*
 612         * Need to raise event.  Since raising
 613         * events can block, we need to do it in
 614         * the main thread.
 615         */
 616        spin_lock_irqsave(&ms->lock, flags);
 617        if (!ms->failures.head)
 618                should_wake = 1;
 619        bio_list_add(&ms->failures, bio);
 620        spin_unlock_irqrestore(&ms->lock, flags);
 621        if (should_wake)
 622                wakeup_mirrord(ms);
 623}
 624
 625static void do_write(struct mirror_set *ms, struct bio *bio)
 626{
 627        unsigned int i;
 628        struct dm_io_region io[ms->nr_mirrors], *dest = io;
 629        struct mirror *m;
 630        struct dm_io_request io_req = {
 631                .bi_rw = WRITE | (bio->bi_rw & WRITE_FLUSH_FUA),
 632                .mem.type = DM_IO_BVEC,
 633                .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
 634                .notify.fn = write_callback,
 635                .notify.context = bio,
 636                .client = ms->io_client,
 637        };
 638
 639        if (bio->bi_rw & REQ_DISCARD) {
 640                io_req.bi_rw |= REQ_DISCARD;
 641                io_req.mem.type = DM_IO_KMEM;
 642                io_req.mem.ptr.addr = NULL;
 643        }
 644
 645        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
 646                map_region(dest++, m, bio);
 647
 648        /*
 649         * Use default mirror because we only need it to retrieve the reference
 650         * to the mirror set in write_callback().
 651         */
 652        bio_set_m(bio, get_default_mirror(ms));
 653
 654        BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL));
 655}
 656
 657static void do_writes(struct mirror_set *ms, struct bio_list *writes)
 658{
 659        int state;
 660        struct bio *bio;
 661        struct bio_list sync, nosync, recover, *this_list = NULL;
 662        struct bio_list requeue;
 663        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
 664        region_t region;
 665
 666        if (!writes->head)
 667                return;
 668
 669        /*
 670         * Classify each write.
 671         */
 672        bio_list_init(&sync);
 673        bio_list_init(&nosync);
 674        bio_list_init(&recover);
 675        bio_list_init(&requeue);
 676
 677        while ((bio = bio_list_pop(writes))) {
 678                if ((bio->bi_rw & REQ_FLUSH) ||
 679                    (bio->bi_rw & REQ_DISCARD)) {
 680                        bio_list_add(&sync, bio);
 681                        continue;
 682                }
 683
 684                region = dm_rh_bio_to_region(ms->rh, bio);
 685
 686                if (log->type->is_remote_recovering &&
 687                    log->type->is_remote_recovering(log, region)) {
 688                        bio_list_add(&requeue, bio);
 689                        continue;
 690                }
 691
 692                state = dm_rh_get_state(ms->rh, region, 1);
 693                switch (state) {
 694                case DM_RH_CLEAN:
 695                case DM_RH_DIRTY:
 696                        this_list = &sync;
 697                        break;
 698
 699                case DM_RH_NOSYNC:
 700                        this_list = &nosync;
 701                        break;
 702
 703                case DM_RH_RECOVERING:
 704                        this_list = &recover;
 705                        break;
 706                }
 707
 708                bio_list_add(this_list, bio);
 709        }
 710
 711        /*
 712         * Add bios that are delayed due to remote recovery
 713         * back on to the write queue
 714         */
 715        if (unlikely(requeue.head)) {
 716                spin_lock_irq(&ms->lock);
 717                bio_list_merge(&ms->writes, &requeue);
 718                spin_unlock_irq(&ms->lock);
 719                delayed_wake(ms);
 720        }
 721
 722        /*
 723         * Increment the pending counts for any regions that will
 724         * be written to (writes to recover regions are going to
 725         * be delayed).
 726         */
 727        dm_rh_inc_pending(ms->rh, &sync);
 728        dm_rh_inc_pending(ms->rh, &nosync);
 729
 730        /*
 731         * If the flush fails on a previous call and succeeds here,
 732         * we must not reset the log_failure variable.  We need
 733         * userspace interaction to do that.
 734         */
 735        ms->log_failure = dm_rh_flush(ms->rh) ? 1 : ms->log_failure;
 736
 737        /*
 738         * Dispatch io.
 739         */
 740        if (unlikely(ms->log_failure) && errors_handled(ms)) {
 741                spin_lock_irq(&ms->lock);
 742                bio_list_merge(&ms->failures, &sync);
 743                spin_unlock_irq(&ms->lock);
 744                wakeup_mirrord(ms);
 745        } else
 746                while ((bio = bio_list_pop(&sync)))
 747                        do_write(ms, bio);
 748
 749        while ((bio = bio_list_pop(&recover)))
 750                dm_rh_delay(ms->rh, bio);
 751
 752        while ((bio = bio_list_pop(&nosync))) {
 753                if (unlikely(ms->leg_failure) && errors_handled(ms)) {
 754                        spin_lock_irq(&ms->lock);
 755                        bio_list_add(&ms->failures, bio);
 756                        spin_unlock_irq(&ms->lock);
 757                        wakeup_mirrord(ms);
 758                } else {
 759                        map_bio(get_default_mirror(ms), bio);
 760                        generic_make_request(bio);
 761                }
 762        }
 763}
 764
 765static void do_failures(struct mirror_set *ms, struct bio_list *failures)
 766{
 767        struct bio *bio;
 768
 769        if (likely(!failures->head))
 770                return;
 771
 772        /*
 773         * If the log has failed, unattempted writes are being
 774         * put on the holds list.  We can't issue those writes
 775         * until a log has been marked, so we must store them.
 776         *
 777         * If a 'noflush' suspend is in progress, we can requeue
 778         * the I/O's to the core.  This give userspace a chance
 779         * to reconfigure the mirror, at which point the core
 780         * will reissue the writes.  If the 'noflush' flag is
 781         * not set, we have no choice but to return errors.
 782         *
 783         * Some writes on the failures list may have been
 784         * submitted before the log failure and represent a
 785         * failure to write to one of the devices.  It is ok
 786         * for us to treat them the same and requeue them
 787         * as well.
 788         */
 789        while ((bio = bio_list_pop(failures))) {
 790                if (!ms->log_failure) {
 791                        ms->in_sync = 0;
 792                        dm_rh_mark_nosync(ms->rh, bio);
 793                }
 794
 795                /*
 796                 * If all the legs are dead, fail the I/O.
 797                 * If we have been told to handle errors, hold the bio
 798                 * and wait for userspace to deal with the problem.
 799                 * Otherwise pretend that the I/O succeeded. (This would
 800                 * be wrong if the failed leg returned after reboot and
 801                 * got replicated back to the good legs.)
 802                 */
 803                if (!get_valid_mirror(ms))
 804                        bio_endio(bio, -EIO);
 805                else if (errors_handled(ms))
 806                        hold_bio(ms, bio);
 807                else
 808                        bio_endio(bio, 0);
 809        }
 810}
 811
 812static void trigger_event(struct work_struct *work)
 813{
 814        struct mirror_set *ms =
 815                container_of(work, struct mirror_set, trigger_event);
 816
 817        dm_table_event(ms->ti->table);
 818}
 819
 820/*-----------------------------------------------------------------
 821 * kmirrord
 822 *---------------------------------------------------------------*/
 823static void do_mirror(struct work_struct *work)
 824{
 825        struct mirror_set *ms = container_of(work, struct mirror_set,
 826                                             kmirrord_work);
 827        struct bio_list reads, writes, failures;
 828        unsigned long flags;
 829
 830        spin_lock_irqsave(&ms->lock, flags);
 831        reads = ms->reads;
 832        writes = ms->writes;
 833        failures = ms->failures;
 834        bio_list_init(&ms->reads);
 835        bio_list_init(&ms->writes);
 836        bio_list_init(&ms->failures);
 837        spin_unlock_irqrestore(&ms->lock, flags);
 838
 839        dm_rh_update_states(ms->rh, errors_handled(ms));
 840        do_recovery(ms);
 841        do_reads(ms, &reads);
 842        do_writes(ms, &writes);
 843        do_failures(ms, &failures);
 844}
 845
 846/*-----------------------------------------------------------------
 847 * Target functions
 848 *---------------------------------------------------------------*/
 849static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 850                                        uint32_t region_size,
 851                                        struct dm_target *ti,
 852                                        struct dm_dirty_log *dl)
 853{
 854        size_t len;
 855        struct mirror_set *ms = NULL;
 856
 857        len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
 858
 859        ms = kzalloc(len, GFP_KERNEL);
 860        if (!ms) {
 861                ti->error = "Cannot allocate mirror context";
 862                return NULL;
 863        }
 864
 865        spin_lock_init(&ms->lock);
 866        bio_list_init(&ms->reads);
 867        bio_list_init(&ms->writes);
 868        bio_list_init(&ms->failures);
 869        bio_list_init(&ms->holds);
 870
 871        ms->ti = ti;
 872        ms->nr_mirrors = nr_mirrors;
 873        ms->nr_regions = dm_sector_div_up(ti->len, region_size);
 874        ms->in_sync = 0;
 875        ms->log_failure = 0;
 876        ms->leg_failure = 0;
 877        atomic_set(&ms->suspend, 0);
 878        atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
 879
 880        ms->io_client = dm_io_client_create();
 881        if (IS_ERR(ms->io_client)) {
 882                ti->error = "Error creating dm_io client";
 883                kfree(ms);
 884                return NULL;
 885        }
 886
 887        ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord,
 888                                       wakeup_all_recovery_waiters,
 889                                       ms->ti->begin, MAX_RECOVERY,
 890                                       dl, region_size, ms->nr_regions);
 891        if (IS_ERR(ms->rh)) {
 892                ti->error = "Error creating dirty region hash";
 893                dm_io_client_destroy(ms->io_client);
 894                kfree(ms);
 895                return NULL;
 896        }
 897
 898        return ms;
 899}
 900
 901static void free_context(struct mirror_set *ms, struct dm_target *ti,
 902                         unsigned int m)
 903{
 904        while (m--)
 905                dm_put_device(ti, ms->mirror[m].dev);
 906
 907        dm_io_client_destroy(ms->io_client);
 908        dm_region_hash_destroy(ms->rh);
 909        kfree(ms);
 910}
 911
 912static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
 913                      unsigned int mirror, char **argv)
 914{
 915        unsigned long long offset;
 916        char dummy;
 917
 918        if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1) {
 919                ti->error = "Invalid offset";
 920                return -EINVAL;
 921        }
 922
 923        if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
 924                          &ms->mirror[mirror].dev)) {
 925                ti->error = "Device lookup failure";
 926                return -ENXIO;
 927        }
 928
 929        ms->mirror[mirror].ms = ms;
 930        atomic_set(&(ms->mirror[mirror].error_count), 0);
 931        ms->mirror[mirror].error_type = 0;
 932        ms->mirror[mirror].offset = offset;
 933
 934        return 0;
 935}
 936
 937/*
 938 * Create dirty log: log_type #log_params <log_params>
 939 */
 940static struct dm_dirty_log *create_dirty_log(struct dm_target *ti,
 941                                             unsigned argc, char **argv,
 942                                             unsigned *args_used)
 943{
 944        unsigned param_count;
 945        struct dm_dirty_log *dl;
 946        char dummy;
 947
 948        if (argc < 2) {
 949                ti->error = "Insufficient mirror log arguments";
 950                return NULL;
 951        }
 952
 953        if (sscanf(argv[1], "%u%c", &param_count, &dummy) != 1) {
 954                ti->error = "Invalid mirror log argument count";
 955                return NULL;
 956        }
 957
 958        *args_used = 2 + param_count;
 959
 960        if (argc < *args_used) {
 961                ti->error = "Insufficient mirror log arguments";
 962                return NULL;
 963        }
 964
 965        dl = dm_dirty_log_create(argv[0], ti, mirror_flush, param_count,
 966                                 argv + 2);
 967        if (!dl) {
 968                ti->error = "Error creating mirror dirty log";
 969                return NULL;
 970        }
 971
 972        return dl;
 973}
 974
 975static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
 976                          unsigned *args_used)
 977{
 978        unsigned num_features;
 979        struct dm_target *ti = ms->ti;
 980        char dummy;
 981
 982        *args_used = 0;
 983
 984        if (!argc)
 985                return 0;
 986
 987        if (sscanf(argv[0], "%u%c", &num_features, &dummy) != 1) {
 988                ti->error = "Invalid number of features";
 989                return -EINVAL;
 990        }
 991
 992        argc--;
 993        argv++;
 994        (*args_used)++;
 995
 996        if (num_features > argc) {
 997                ti->error = "Not enough arguments to support feature count";
 998                return -EINVAL;
 999        }
1000
1001        if (!strcmp("handle_errors", argv[0]))
1002                ms->features |= DM_RAID1_HANDLE_ERRORS;
1003        else {
1004                ti->error = "Unrecognised feature requested";
1005                return -EINVAL;
1006        }
1007
1008        (*args_used)++;
1009
1010        return 0;
1011}
1012
1013/*
1014 * Construct a mirror mapping:
1015 *
1016 * log_type #log_params <log_params>
1017 * #mirrors [mirror_path offset]{2,}
1018 * [#features <features>]
1019 *
1020 * log_type is "core" or "disk"
1021 * #log_params is between 1 and 3
1022 *
1023 * If present, features must be "handle_errors".
1024 */
1025static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1026{
1027        int r;
1028        unsigned int nr_mirrors, m, args_used;
1029        struct mirror_set *ms;
1030        struct dm_dirty_log *dl;
1031        char dummy;
1032
1033        dl = create_dirty_log(ti, argc, argv, &args_used);
1034        if (!dl)
1035                return -EINVAL;
1036
1037        argv += args_used;
1038        argc -= args_used;
1039
1040        if (!argc || sscanf(argv[0], "%u%c", &nr_mirrors, &dummy) != 1 ||
1041            nr_mirrors < 2 || nr_mirrors > DM_KCOPYD_MAX_REGIONS + 1) {
1042                ti->error = "Invalid number of mirrors";
1043                dm_dirty_log_destroy(dl);
1044                return -EINVAL;
1045        }
1046
1047        argv++, argc--;
1048
1049        if (argc < nr_mirrors * 2) {
1050                ti->error = "Too few mirror arguments";
1051                dm_dirty_log_destroy(dl);
1052                return -EINVAL;
1053        }
1054
1055        ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
1056        if (!ms) {
1057                dm_dirty_log_destroy(dl);
1058                return -ENOMEM;
1059        }
1060
1061        /* Get the mirror parameter sets */
1062        for (m = 0; m < nr_mirrors; m++) {
1063                r = get_mirror(ms, ti, m, argv);
1064                if (r) {
1065                        free_context(ms, ti, m);
1066                        return r;
1067                }
1068                argv += 2;
1069                argc -= 2;
1070        }
1071
1072        ti->private = ms;
1073
1074        r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
1075        if (r)
1076                goto err_free_context;
1077
1078        ti->num_flush_bios = 1;
1079        ti->num_discard_bios = 1;
1080        ti->per_bio_data_size = sizeof(struct dm_raid1_bio_record);
1081        ti->discard_zeroes_data_unsupported = true;
1082
1083        ms->kmirrord_wq = alloc_workqueue("kmirrord",
1084                                          WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
1085        if (!ms->kmirrord_wq) {
1086                DMERR("couldn't start kmirrord");
1087                r = -ENOMEM;
1088                goto err_free_context;
1089        }
1090        INIT_WORK(&ms->kmirrord_work, do_mirror);
1091        init_timer(&ms->timer);
1092        ms->timer_pending = 0;
1093        INIT_WORK(&ms->trigger_event, trigger_event);
1094
1095        r = parse_features(ms, argc, argv, &args_used);
1096        if (r)
1097                goto err_destroy_wq;
1098
1099        argv += args_used;
1100        argc -= args_used;
1101
1102        /*
1103         * Any read-balancing addition depends on the
1104         * DM_RAID1_HANDLE_ERRORS flag being present.
1105         * This is because the decision to balance depends
1106         * on the sync state of a region.  If the above
1107         * flag is not present, we ignore errors; and
1108         * the sync state may be inaccurate.
1109         */
1110
1111        if (argc) {
1112                ti->error = "Too many mirror arguments";
1113                r = -EINVAL;
1114                goto err_destroy_wq;
1115        }
1116
1117        ms->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
1118        if (IS_ERR(ms->kcopyd_client)) {
1119                r = PTR_ERR(ms->kcopyd_client);
1120                goto err_destroy_wq;
1121        }
1122
1123        wakeup_mirrord(ms);
1124        return 0;
1125
1126err_destroy_wq:
1127        destroy_workqueue(ms->kmirrord_wq);
1128err_free_context:
1129        free_context(ms, ti, ms->nr_mirrors);
1130        return r;
1131}
1132
1133static void mirror_dtr(struct dm_target *ti)
1134{
1135        struct mirror_set *ms = (struct mirror_set *) ti->private;
1136
1137        del_timer_sync(&ms->timer);
1138        flush_workqueue(ms->kmirrord_wq);
1139        flush_work(&ms->trigger_event);
1140        dm_kcopyd_client_destroy(ms->kcopyd_client);
1141        destroy_workqueue(ms->kmirrord_wq);
1142        free_context(ms, ti, ms->nr_mirrors);
1143}
1144
1145/*
1146 * Mirror mapping function
1147 */
1148static int mirror_map(struct dm_target *ti, struct bio *bio)
1149{
1150        int r, rw = bio_rw(bio);
1151        struct mirror *m;
1152        struct mirror_set *ms = ti->private;
1153        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1154        struct dm_raid1_bio_record *bio_record =
1155          dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
1156
1157        bio_record->details.bi_bdev = NULL;
1158
1159        if (rw == WRITE) {
1160                /* Save region for mirror_end_io() handler */
1161                bio_record->write_region = dm_rh_bio_to_region(ms->rh, bio);
1162                queue_bio(ms, bio, rw);
1163                return DM_MAPIO_SUBMITTED;
1164        }
1165
1166        r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
1167        if (r < 0 && r != -EWOULDBLOCK)
1168                return r;
1169
1170        /*
1171         * If region is not in-sync queue the bio.
1172         */
1173        if (!r || (r == -EWOULDBLOCK)) {
1174                if (rw == READA)
1175                        return -EWOULDBLOCK;
1176
1177                queue_bio(ms, bio, rw);
1178                return DM_MAPIO_SUBMITTED;
1179        }
1180
1181        /*
1182         * The region is in-sync and we can perform reads directly.
1183         * Store enough information so we can retry if it fails.
1184         */
1185        m = choose_mirror(ms, bio->bi_sector);
1186        if (unlikely(!m))
1187                return -EIO;
1188
1189        dm_bio_record(&bio_record->details, bio);
1190        bio_record->m = m;
1191
1192        map_bio(m, bio);
1193
1194        return DM_MAPIO_REMAPPED;
1195}
1196
1197static int mirror_end_io(struct dm_target *ti, struct bio *bio, int error)
1198{
1199        int rw = bio_rw(bio);
1200        struct mirror_set *ms = (struct mirror_set *) ti->private;
1201        struct mirror *m = NULL;
1202        struct dm_bio_details *bd = NULL;
1203        struct dm_raid1_bio_record *bio_record =
1204          dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
1205
1206        /*
1207         * We need to dec pending if this was a write.
1208         */
1209        if (rw == WRITE) {
1210                if (!(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD)))
1211                        dm_rh_dec(ms->rh, bio_record->write_region);
1212                return error;
1213        }
1214
1215        if (error == -EOPNOTSUPP)
1216                goto out;
1217
1218        if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
1219                goto out;
1220
1221        if (unlikely(error)) {
1222                if (!bio_record->details.bi_bdev) {
1223                        /*
1224                         * There wasn't enough memory to record necessary
1225                         * information for a retry or there was no other
1226                         * mirror in-sync.
1227                         */
1228                        DMERR_LIMIT("Mirror read failed.");
1229                        return -EIO;
1230                }
1231
1232                m = bio_record->m;
1233
1234                DMERR("Mirror read failed from %s. Trying alternative device.",
1235                      m->dev->name);
1236
1237                fail_mirror(m, DM_RAID1_READ_ERROR);
1238
1239                /*
1240                 * A failed read is requeued for another attempt using an intact
1241                 * mirror.
1242                 */
1243                if (default_ok(m) || mirror_available(ms, bio)) {
1244                        bd = &bio_record->details;
1245
1246                        dm_bio_restore(bd, bio);
1247                        bio_record->details.bi_bdev = NULL;
1248                        queue_bio(ms, bio, rw);
1249                        return DM_ENDIO_INCOMPLETE;
1250                }
1251                DMERR("All replicated volumes dead, failing I/O");
1252        }
1253
1254out:
1255        bio_record->details.bi_bdev = NULL;
1256
1257        return error;
1258}
1259
1260static void mirror_presuspend(struct dm_target *ti)
1261{
1262        struct mirror_set *ms = (struct mirror_set *) ti->private;
1263        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1264
1265        struct bio_list holds;
1266        struct bio *bio;
1267
1268        atomic_set(&ms->suspend, 1);
1269
1270        /*
1271         * Process bios in the hold list to start recovery waiting
1272         * for bios in the hold list. After the process, no bio has
1273         * a chance to be added in the hold list because ms->suspend
1274         * is set.
1275         */
1276        spin_lock_irq(&ms->lock);
1277        holds = ms->holds;
1278        bio_list_init(&ms->holds);
1279        spin_unlock_irq(&ms->lock);
1280
1281        while ((bio = bio_list_pop(&holds)))
1282                hold_bio(ms, bio);
1283
1284        /*
1285         * We must finish up all the work that we've
1286         * generated (i.e. recovery work).
1287         */
1288        dm_rh_stop_recovery(ms->rh);
1289
1290        wait_event(_kmirrord_recovery_stopped,
1291                   !dm_rh_recovery_in_flight(ms->rh));
1292
1293        if (log->type->presuspend && log->type->presuspend(log))
1294                /* FIXME: need better error handling */
1295                DMWARN("log presuspend failed");
1296
1297        /*
1298         * Now that recovery is complete/stopped and the
1299         * delayed bios are queued, we need to wait for
1300         * the worker thread to complete.  This way,
1301         * we know that all of our I/O has been pushed.
1302         */
1303        flush_workqueue(ms->kmirrord_wq);
1304}
1305
1306static void mirror_postsuspend(struct dm_target *ti)
1307{
1308        struct mirror_set *ms = ti->private;
1309        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1310
1311        if (log->type->postsuspend && log->type->postsuspend(log))
1312                /* FIXME: need better error handling */
1313                DMWARN("log postsuspend failed");
1314}
1315
1316static void mirror_resume(struct dm_target *ti)
1317{
1318        struct mirror_set *ms = ti->private;
1319        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1320
1321        atomic_set(&ms->suspend, 0);
1322        if (log->type->resume && log->type->resume(log))
1323                /* FIXME: need better error handling */
1324                DMWARN("log resume failed");
1325        dm_rh_start_recovery(ms->rh);
1326}
1327
1328/*
1329 * device_status_char
1330 * @m: mirror device/leg we want the status of
1331 *
1332 * We return one character representing the most severe error
1333 * we have encountered.
1334 *    A => Alive - No failures
1335 *    D => Dead - A write failure occurred leaving mirror out-of-sync
1336 *    S => Sync - A sychronization failure occurred, mirror out-of-sync
1337 *    R => Read - A read failure occurred, mirror data unaffected
1338 *
1339 * Returns: <char>
1340 */
1341static char device_status_char(struct mirror *m)
1342{
1343        if (!atomic_read(&(m->error_count)))
1344                return 'A';
1345
1346        return (test_bit(DM_RAID1_FLUSH_ERROR, &(m->error_type))) ? 'F' :
1347                (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' :
1348                (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' :
1349                (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
1350}
1351
1352
1353static void mirror_status(struct dm_target *ti, status_type_t type,
1354                          unsigned status_flags, char *result, unsigned maxlen)
1355{
1356        unsigned int m, sz = 0;
1357        struct mirror_set *ms = (struct mirror_set *) ti->private;
1358        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
1359        char buffer[ms->nr_mirrors + 1];
1360
1361        switch (type) {
1362        case STATUSTYPE_INFO:
1363                DMEMIT("%d ", ms->nr_mirrors);
1364                for (m = 0; m < ms->nr_mirrors; m++) {
1365                        DMEMIT("%s ", ms->mirror[m].dev->name);
1366                        buffer[m] = device_status_char(&(ms->mirror[m]));
1367                }
1368                buffer[m] = '\0';
1369
1370                DMEMIT("%llu/%llu 1 %s ",
1371                      (unsigned long long)log->type->get_sync_count(log),
1372                      (unsigned long long)ms->nr_regions, buffer);
1373
1374                sz += log->type->status(log, type, result+sz, maxlen-sz);
1375
1376                break;
1377
1378        case STATUSTYPE_TABLE:
1379                sz = log->type->status(log, type, result, maxlen);
1380
1381                DMEMIT("%d", ms->nr_mirrors);
1382                for (m = 0; m < ms->nr_mirrors; m++)
1383                        DMEMIT(" %s %llu", ms->mirror[m].dev->name,
1384                               (unsigned long long)ms->mirror[m].offset);
1385
1386                if (ms->features & DM_RAID1_HANDLE_ERRORS)
1387                        DMEMIT(" 1 handle_errors");
1388        }
1389}
1390
1391static int mirror_iterate_devices(struct dm_target *ti,
1392                                  iterate_devices_callout_fn fn, void *data)
1393{
1394        struct mirror_set *ms = ti->private;
1395        int ret = 0;
1396        unsigned i;
1397
1398        for (i = 0; !ret && i < ms->nr_mirrors; i++)
1399                ret = fn(ti, ms->mirror[i].dev,
1400                         ms->mirror[i].offset, ti->len, data);
1401
1402        return ret;
1403}
1404
1405static struct target_type mirror_target = {
1406        .name    = "mirror",
1407        .version = {1, 13, 2},
1408        .module  = THIS_MODULE,
1409        .ctr     = mirror_ctr,
1410        .dtr     = mirror_dtr,
1411        .map     = mirror_map,
1412        .end_io  = mirror_end_io,
1413        .presuspend = mirror_presuspend,
1414        .postsuspend = mirror_postsuspend,
1415        .resume  = mirror_resume,
1416        .status  = mirror_status,
1417        .iterate_devices = mirror_iterate_devices,
1418};
1419
1420static int __init dm_mirror_init(void)
1421{
1422        int r;
1423
1424        r = dm_register_target(&mirror_target);
1425        if (r < 0) {
1426                DMERR("Failed to register mirror target");
1427                goto bad_target;
1428        }
1429
1430        return 0;
1431
1432bad_target:
1433        return r;
1434}
1435
1436static void __exit dm_mirror_exit(void)
1437{
1438        dm_unregister_target(&mirror_target);
1439}
1440
1441/* Module hooks */
1442module_init(dm_mirror_init);
1443module_exit(dm_mirror_exit);
1444
1445MODULE_DESCRIPTION(DM_NAME " mirror target");
1446MODULE_AUTHOR("Joe Thornber");
1447MODULE_LICENSE("GPL");
1448
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