drivers/md/dm-raid.c

   1 /*
   2  * Copyright (C) 2010-2011 Neil Brown
   3  * Copyright (C) 2010-2011 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/slab.h>
   9
  10 #include "md.h"
  11 #include "raid5.h"
  12 #include "dm.h"
  13 #include "bitmap.h"
  14
  15 #define DM_MSG_PREFIX "raid"
  16
  17 /*
  18  * If the MD doesn't support MD_SYNC_STATE_FORCED yet, then
  19  * make it so the flag doesn't set anything.
  20  */
  21 #ifndef MD_SYNC_STATE_FORCED
  22 #define MD_SYNC_STATE_FORCED 0
  23 #endif
  24
  25 struct raid_dev {
  26         /*
  27          * Two DM devices, one to hold metadata and one to hold the
  28          * actual data/parity.  The reason for this is to not confuse
  29          * ti->len and give more flexibility in altering size and
  30          * characteristics.
  31          *
  32          * While it is possible for this device to be associated
  33          * with a different physical device than the data_dev, it
  34          * is intended for it to be the same.
  35          *    |--------- Physical Device ---------|
  36          *    |- meta_dev -|------ data_dev ------|
  37          */
  38         struct dm_dev *meta_dev;
  39         struct dm_dev *data_dev;
  40         struct mdk_rdev_s rdev;
  41 };
  42
  43 /*
  44  * Flags for rs->print_flags field.
  45  */
  46 #define DMPF_DAEMON_SLEEP      0x1
  47 #define DMPF_MAX_WRITE_BEHIND  0x2
  48 #define DMPF_SYNC              0x4
  49 #define DMPF_NOSYNC            0x8
  50 #define DMPF_STRIPE_CACHE      0x10
  51 #define DMPF_MIN_RECOVERY_RATE 0x20
  52 #define DMPF_MAX_RECOVERY_RATE 0x40
  53
  54 struct raid_set {
  55         struct dm_target *ti;
  56
  57         uint64_t print_flags;
  58
  59         struct mddev_s md;
  60         struct raid_type *raid_type;
  61         struct dm_target_callbacks callbacks;
  62
  63         struct raid_dev dev[0];
  64 };
  65
  66 /* Supported raid types and properties. */
  67 static struct raid_type {
  68         const char *name;               /* RAID algorithm. */
  69         const char *descr;              /* Descriptor text for logging. */
  70         const unsigned parity_devs;     /* # of parity devices. */
  71         const unsigned minimal_devs;    /* minimal # of devices in set. */
  72         const unsigned level;           /* RAID level. */
  73         const unsigned algorithm;       /* RAID algorithm. */
  74 } raid_types[] = {
  75         {"raid4",    "RAID4 (dedicated parity disk)",   1, 2, 5, ALGORITHM_PARITY_0},
  76         {"raid5_la", "RAID5 (left asymmetric)",         1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
  77         {"raid5_ra", "RAID5 (right asymmetric)",        1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
  78         {"raid5_ls", "RAID5 (left symmetric)",          1, 2, 5, ALGORITHM_LEFT_SYMMETRIC},
  79         {"raid5_rs", "RAID5 (right symmetric)",         1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC},
  80         {"raid6_zr", "RAID6 (zero restart)",            2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART},
  81         {"raid6_nr", "RAID6 (N restart)",               2, 4, 6, ALGORITHM_ROTATING_N_RESTART},
  82         {"raid6_nc", "RAID6 (N continue)",              2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
  83 };
  84
  85 static struct raid_type *get_raid_type(char *name)
  86 {
  87         int i;
  88
  89         for (i = 0; i < ARRAY_SIZE(raid_types); i++)
  90                 if (!strcmp(raid_types[i].name, name))
  91                         return &raid_types[i];
  92
  93         return NULL;
  94 }
  95
  96 static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *raid_type, unsigned raid_devs)
  97 {
  98         unsigned i;
  99         struct raid_set *rs;
 100         sector_t sectors_per_dev;
 101
 102         if (raid_devs <= raid_type->parity_devs) {
 103                 ti->error = "Insufficient number of devices";
 104                 return ERR_PTR(-EINVAL);
 105         }
 106
 107         sectors_per_dev = ti->len;
 108         if (sector_div(sectors_per_dev, (raid_devs - raid_type->parity_devs))) {
 109                 ti->error = "Target length not divisible by number of data devices";
 110                 return ERR_PTR(-EINVAL);
 111         }
 112
 113         rs = kzalloc(sizeof(*rs) + raid_devs * sizeof(rs->dev[0]), GFP_KERNEL);
 114         if (!rs) {
 115                 ti->error = "Cannot allocate raid context";
 116                 return ERR_PTR(-ENOMEM);
 117         }
 118
 119         mddev_init(&rs->md);
 120
 121         rs->ti = ti;
 122         rs->raid_type = raid_type;
 123         rs->md.raid_disks = raid_devs;
 124         rs->md.level = raid_type->level;
 125         rs->md.new_level = rs->md.level;
 126         rs->md.dev_sectors = sectors_per_dev;
 127         rs->md.layout = raid_type->algorithm;
 128         rs->md.new_layout = rs->md.layout;
 129         rs->md.delta_disks = 0;
 130         rs->md.recovery_cp = 0;
 131
 132         for (i = 0; i < raid_devs; i++)
 133                 md_rdev_init(&rs->dev[i].rdev);
 134
 135         /*
 136          * Remaining items to be initialized by further RAID params:
 137          *  rs->md.persistent
 138          *  rs->md.external
 139          *  rs->md.chunk_sectors
 140          *  rs->md.new_chunk_sectors
 141          */
 142
 143         return rs;
 144 }
 145
 146 static void context_free(struct raid_set *rs)
 147 {
 148         int i;
 149
 150         for (i = 0; i < rs->md.raid_disks; i++)
 151                 if (rs->dev[i].data_dev)
 152                         dm_put_device(rs->ti, rs->dev[i].data_dev);
 153
 154         kfree(rs);
 155 }
 156
 157 /*
 158  * For every device we have two words
 159  *  <meta_dev>: meta device name or '-' if missing
 160  *  <data_dev>: data device name or '-' if missing
 161  *
 162  * This code parses those words.
 163  */
 164 static int dev_parms(struct raid_set *rs, char **argv)
 165 {
 166         int i;
 167         int rebuild = 0;
 168         int metadata_available = 0;
 169         int ret = 0;
 170
 171         for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
 172                 rs->dev[i].rdev.raid_disk = i;
 173
 174                 rs->dev[i].meta_dev = NULL;
 175                 rs->dev[i].data_dev = NULL;
 176
 177                 /*
 178                  * There are no offsets, since there is a separate device
 179                  * for data and metadata.
 180                  */
 181                 rs->dev[i].rdev.data_offset = 0;
 182                 rs->dev[i].rdev.mddev = &rs->md;
 183
 184                 if (strcmp(argv[0], "-")) {
 185                         rs->ti->error = "Metadata devices not supported";
 186                         return -EINVAL;
 187                 }
 188
 189                 if (!strcmp(argv[1], "-")) {
 190                         if (!test_bit(In_sync, &rs->dev[i].rdev.flags) &&
 191                             (!rs->dev[i].rdev.recovery_offset)) {
 192                                 rs->ti->error = "Drive designated for rebuild not specified";
 193                                 return -EINVAL;
 194                         }
 195
 196                         continue;
 197                 }
 198
 199                 ret = dm_get_device(rs->ti, argv[1],
 200                                     dm_table_get_mode(rs->ti->table),
 201                                     &rs->dev[i].data_dev);
 202                 if (ret) {
 203                         rs->ti->error = "RAID device lookup failure";
 204                         return ret;
 205                 }
 206
 207                 rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
 208                 list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
 209                 if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
 210                         rebuild++;
 211         }
 212
 213         if (metadata_available) {
 214                 rs->md.external = 0;
 215                 rs->md.persistent = 1;
 216                 rs->md.major_version = 2;
 217         } else if (rebuild && !rs->md.recovery_cp) {
 218                 /*
 219                  * Without metadata, we will not be able to tell if the array
 220                  * is in-sync or not - we must assume it is not.  Therefore,
 221                  * it is impossible to rebuild a drive.
 222                  *
 223                  * Even if there is metadata, the on-disk information may
 224                  * indicate that the array is not in-sync and it will then
 225                  * fail at that time.
 226                  *
 227                  * User could specify 'nosync' option if desperate.
 228                  */
 229                 DMERR("Unable to rebuild drive while array is not in-sync");
 230                 rs->ti->error = "RAID device lookup failure";
 231                 return -EINVAL;
 232         }
 233
 234         return 0;
 235 }
 236
 237 /*
 238  * Possible arguments are...
 239  * RAID456:
 240  *      <chunk_size> [optional_args]
 241  *
 242  * Optional args:
 243  *    [[no]sync]                        Force or prevent recovery of the entire array
 244  *    [rebuild <idx>]                   Rebuild the drive indicated by the index
 245  *    [daemon_sleep <ms>]               Time between bitmap daemon work to clear bits
 246  *    [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
 247  *    [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
 248  *    [max_write_behind <sectors>]      See '-write-behind=' (man mdadm)
 249  *    [stripe_cache <sectors>]          Stripe cache size for higher RAIDs
 250  */
 251 static int parse_raid_params(struct raid_set *rs, char **argv,
 252                              unsigned num_raid_params)
 253 {
 254         unsigned i, rebuild_cnt = 0;
 255         unsigned long value;
 256         char *key;
 257
 258         /*
 259          * First, parse the in-order required arguments
 260          */
 261         if ((strict_strtoul(argv[0], 10, &value) < 0) ||
 262             !is_power_of_2(value) || (value < 8)) {
 263                 rs->ti->error = "Bad chunk size";
 264                 return -EINVAL;
 265         }
 266
 267         rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
 268         argv++;
 269         num_raid_params--;
 270
 271         /*
 272          * Second, parse the unordered optional arguments
 273          */
 274         for (i = 0; i < rs->md.raid_disks; i++)
 275                 set_bit(In_sync, &rs->dev[i].rdev.flags);
 276
 277         for (i = 0; i < num_raid_params; i++) {
 278                 if (!strcmp(argv[i], "nosync")) {
 279                         rs->md.recovery_cp = MaxSector;
 280                         rs->print_flags |= DMPF_NOSYNC;
 281                         rs->md.flags |= MD_SYNC_STATE_FORCED;
 282                         continue;
 283                 }
 284                 if (!strcmp(argv[i], "sync")) {
 285                         rs->md.recovery_cp = 0;
 286                         rs->print_flags |= DMPF_SYNC;
 287                         rs->md.flags |= MD_SYNC_STATE_FORCED;
 288                         continue;
 289                 }
 290
 291                 /* The rest of the optional arguments come in key/value pairs */
 292                 if ((i + 1) >= num_raid_params) {
 293                         rs->ti->error = "Wrong number of raid parameters given";
 294                         return -EINVAL;
 295                 }
 296
 297                 key = argv[i++];
 298                 if (strict_strtoul(argv[i], 10, &value) < 0) {
 299                         rs->ti->error = "Bad numerical argument given in raid params";
 300                         return -EINVAL;
 301                 }
 302
 303                 if (!strcmp(key, "rebuild")) {
 304                         if (++rebuild_cnt > rs->raid_type->parity_devs) {
 305                                 rs->ti->error = "Too many rebuild drives given";
 306                                 return -EINVAL;
 307                         }
 308                         if (value > rs->md.raid_disks) {
 309                                 rs->ti->error = "Invalid rebuild index given";
 310                                 return -EINVAL;
 311                         }
 312                         clear_bit(In_sync, &rs->dev[value].rdev.flags);
 313                         rs->dev[value].rdev.recovery_offset = 0;
 314                 } else if (!strcmp(key, "max_write_behind")) {
 315                         rs->print_flags |= DMPF_MAX_WRITE_BEHIND;
 316
 317                         /*
 318                          * In device-mapper, we specify things in sectors, but
 319                          * MD records this value in kB
 320                          */
 321                         value /= 2;
 322                         if (value > COUNTER_MAX) {
 323                                 rs->ti->error = "Max write-behind limit out of range";
 324                                 return -EINVAL;
 325                         }
 326                         rs->md.bitmap_info.max_write_behind = value;
 327                 } else if (!strcmp(key, "daemon_sleep")) {
 328                         rs->print_flags |= DMPF_DAEMON_SLEEP;
 329                         if (!value || (value > MAX_SCHEDULE_TIMEOUT)) {
 330                                 rs->ti->error = "daemon sleep period out of range";
 331                                 return -EINVAL;
 332                         }
 333                         rs->md.bitmap_info.daemon_sleep = value;
 334                 } else if (!strcmp(key, "stripe_cache")) {
 335                         rs->print_flags |= DMPF_STRIPE_CACHE;
 336
 337                         /*
 338                          * In device-mapper, we specify things in sectors, but
 339                          * MD records this value in kB
 340                          */
 341                         value /= 2;
 342
 343                         if (rs->raid_type->level < 5) {
 344                                 rs->ti->error = "Inappropriate argument: stripe_cache";
 345                                 return -EINVAL;
 346                         }
 347                         if (raid5_set_cache_size(&rs->md, (int)value)) {
 348                                 rs->ti->error = "Bad stripe_cache size";
 349                                 return -EINVAL;
 350                         }
 351                 } else if (!strcmp(key, "min_recovery_rate")) {
 352                         rs->print_flags |= DMPF_MIN_RECOVERY_RATE;
 353                         if (value > INT_MAX) {
 354                                 rs->ti->error = "min_recovery_rate out of range";
 355                                 return -EINVAL;
 356                         }
 357                         rs->md.sync_speed_min = (int)value;
 358                 } else if (!strcmp(key, "max_recovery_rate")) {
 359                         rs->print_flags |= DMPF_MAX_RECOVERY_RATE;
 360                         if (value > INT_MAX) {
 361                                 rs->ti->error = "max_recovery_rate out of range";
 362                                 return -EINVAL;
 363                         }
 364                         rs->md.sync_speed_max = (int)value;
 365                 } else {
 366                         DMERR("Unable to parse RAID parameter: %s", key);
 367                         rs->ti->error = "Unable to parse RAID parameters";
 368                         return -EINVAL;
 369                 }
 370         }
 371
 372         /* Assume there are no metadata devices until the drives are parsed */
 373         rs->md.persistent = 0;
 374         rs->md.external = 1;
 375
 376         return 0;
 377 }
 378
 379 static void do_table_event(struct work_struct *ws)
 380 {
 381         struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
 382
 383         dm_table_event(rs->ti->table);
 384 }
 385
 386 static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
 387 {
 388         struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
 389
 390         return md_raid5_congested(&rs->md, bits);
 391 }
 392
 393 /*
 394  * Construct a RAID4/5/6 mapping:
 395  * Args:
 396  *      <raid_type> <#raid_params> <raid_params>                \
 397  *      <#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
 398  *
 399  * ** metadata devices are not supported yet, use '-' instead **
 400  *
 401  * <raid_params> varies by <raid_type>.  See 'parse_raid_params' for
 402  * details on possible <raid_params>.
 403  */
 404 static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 405 {
 406         int ret;
 407         struct raid_type *rt;
 408         unsigned long num_raid_params, num_raid_devs;
 409         struct raid_set *rs = NULL;
 410
 411         /* Must have at least <raid_type> <#raid_params> */
 412         if (argc < 2) {
 413                 ti->error = "Too few arguments";
 414                 return -EINVAL;
 415         }
 416
 417         /* raid type */
 418         rt = get_raid_type(argv[0]);
 419         if (!rt) {
 420                 ti->error = "Unrecognised raid_type";
 421                 return -EINVAL;
 422         }
 423         argc--;
 424         argv++;
 425
 426         /* number of RAID parameters */
 427         if (strict_strtoul(argv[0], 10, &num_raid_params) < 0) {
 428                 ti->error = "Cannot understand number of RAID parameters";
 429                 return -EINVAL;
 430         }
 431         argc--;
 432         argv++;
 433
 434         /* Skip over RAID params for now and find out # of devices */
 435         if (num_raid_params + 1 > argc) {
 436                 ti->error = "Arguments do not agree with counts given";
 437                 return -EINVAL;
 438         }
 439
 440         if ((strict_strtoul(argv[num_raid_params], 10, &num_raid_devs) < 0) ||
 441             (num_raid_devs >= INT_MAX)) {
 442                 ti->error = "Cannot understand number of raid devices";
 443                 return -EINVAL;
 444         }
 445
 446         rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
 447         if (IS_ERR(rs))
 448                 return PTR_ERR(rs);
 449
 450         ret = parse_raid_params(rs, argv, (unsigned)num_raid_params);
 451         if (ret)
 452                 goto bad;
 453
 454         ret = -EINVAL;
 455
 456         argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
 457         argv += num_raid_params + 1;
 458
 459         if (argc != (num_raid_devs * 2)) {
 460                 ti->error = "Supplied RAID devices does not match the count given";
 461                 goto bad;
 462         }
 463
 464         ret = dev_parms(rs, argv);
 465         if (ret)
 466                 goto bad;
 467
 468         INIT_WORK(&rs->md.event_work, do_table_event);
 469         ti->split_io = rs->md.chunk_sectors;
 470         ti->private = rs;
 471
 472         mutex_lock(&rs->md.reconfig_mutex);
 473         ret = md_run(&rs->md);
 474         rs->md.in_sync = 0; /* Assume already marked dirty */
 475         mutex_unlock(&rs->md.reconfig_mutex);
 476
 477         if (ret) {
 478                 ti->error = "Fail to run raid array";
 479                 goto bad;
 480         }
 481
 482         rs->callbacks.congested_fn = raid_is_congested;
 483         dm_table_add_target_callbacks(ti->table, &rs->callbacks);
 484
 485         return 0;
 486
 487 bad:
 488         context_free(rs);
 489
 490         return ret;
 491 }
 492
 493 static void raid_dtr(struct dm_target *ti)
 494 {
 495         struct raid_set *rs = ti->private;
 496
 497         list_del_init(&rs->callbacks.list);
 498         md_stop(&rs->md);
 499         context_free(rs);
 500 }
 501
 502 static int raid_map(struct dm_target *ti, struct bio *bio, union map_info *map_context)
 503 {
 504         struct raid_set *rs = ti->private;
 505         mddev_t *mddev = &rs->md;
 506
 507         mddev->pers->make_request(mddev, bio);
 508
 509         return DM_MAPIO_SUBMITTED;
 510 }
 511
 512 static int raid_status(struct dm_target *ti, status_type_t type,
 513                        char *result, unsigned maxlen)
 514 {
 515         struct raid_set *rs = ti->private;
 516         unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
 517         unsigned sz = 0;
 518         int i;
 519         sector_t sync;
 520
 521         switch (type) {
 522         case STATUSTYPE_INFO:
 523                 DMEMIT("%s %d ", rs->raid_type->name, rs->md.raid_disks);
 524
 525                 for (i = 0; i < rs->md.raid_disks; i++) {
 526                         if (test_bit(Faulty, &rs->dev[i].rdev.flags))
 527                                 DMEMIT("D");
 528                         else if (test_bit(In_sync, &rs->dev[i].rdev.flags))
 529                                 DMEMIT("A");
 530                         else
 531                                 DMEMIT("a");
 532                 }
 533
 534                 if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery))
 535                         sync = rs->md.curr_resync_completed;
 536                 else
 537                         sync = rs->md.recovery_cp;
 538
 539                 if (sync > rs->md.resync_max_sectors)
 540                         sync = rs->md.resync_max_sectors;
 541
 542                 DMEMIT(" %llu/%llu",
 543                        (unsigned long long) sync,
 544                        (unsigned long long) rs->md.resync_max_sectors);
 545
 546                 break;
 547         case STATUSTYPE_TABLE:
 548                 /* The string you would use to construct this array */
 549                 for (i = 0; i < rs->md.raid_disks; i++)
 550                         if (rs->dev[i].data_dev &&
 551                             !test_bit(In_sync, &rs->dev[i].rdev.flags))
 552                                 raid_param_cnt++; /* for rebuilds */
 553
 554                 raid_param_cnt += (hweight64(rs->print_flags) * 2);
 555                 if (rs->print_flags & (DMPF_SYNC | DMPF_NOSYNC))
 556                         raid_param_cnt--;
 557
 558                 DMEMIT("%s %u %u", rs->raid_type->name,
 559                        raid_param_cnt, rs->md.chunk_sectors);
 560
 561                 if ((rs->print_flags & DMPF_SYNC) &&
 562                     (rs->md.recovery_cp == MaxSector))
 563                         DMEMIT(" sync");
 564                 if (rs->print_flags & DMPF_NOSYNC)
 565                         DMEMIT(" nosync");
 566
 567                 for (i = 0; i < rs->md.raid_disks; i++)
 568                         if (rs->dev[i].data_dev &&
 569                             !test_bit(In_sync, &rs->dev[i].rdev.flags))
 570                                 DMEMIT(" rebuild %u", i);
 571
 572                 if (rs->print_flags & DMPF_DAEMON_SLEEP)
 573                         DMEMIT(" daemon_sleep %lu",
 574                                rs->md.bitmap_info.daemon_sleep);
 575
 576                 if (rs->print_flags & DMPF_MIN_RECOVERY_RATE)
 577                         DMEMIT(" min_recovery_rate %d", rs->md.sync_speed_min);
 578
 579                 if (rs->print_flags & DMPF_MAX_RECOVERY_RATE)
 580                         DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);
 581
 582                 if (rs->print_flags & DMPF_MAX_WRITE_BEHIND)
 583                         DMEMIT(" max_write_behind %lu",
 584                                rs->md.bitmap_info.max_write_behind);
 585
 586                 if (rs->print_flags & DMPF_STRIPE_CACHE) {
 587                         raid5_conf_t *conf = rs->md.private;
 588
 589                         /* convert from kiB to sectors */
 590                         DMEMIT(" stripe_cache %d",
 591                                conf ? conf->max_nr_stripes * 2 : 0);
 592                 }
 593
 594                 DMEMIT(" %d", rs->md.raid_disks);
 595                 for (i = 0; i < rs->md.raid_disks; i++) {
 596                         DMEMIT(" -"); /* metadata device */
 597
 598                         if (rs->dev[i].data_dev)
 599                                 DMEMIT(" %s", rs->dev[i].data_dev->name);
 600                         else
 601                                 DMEMIT(" -");
 602                 }
 603         }
 604
 605         return 0;
 606 }
 607
 608 static int raid_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 609 {
 610         struct raid_set *rs = ti->private;
 611         unsigned i;
 612         int ret = 0;
 613
 614         for (i = 0; !ret && i < rs->md.raid_disks; i++)
 615                 if (rs->dev[i].data_dev)
 616                         ret = fn(ti,
 617                                  rs->dev[i].data_dev,
 618                                  0, /* No offset on data devs */
 619                                  rs->md.dev_sectors,
 620                                  data);
 621
 622         return ret;
 623 }
 624
 625 static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
 626 {
 627         struct raid_set *rs = ti->private;
 628         unsigned chunk_size = rs->md.chunk_sectors << 9;
 629         raid5_conf_t *conf = rs->md.private;
 630
 631         blk_limits_io_min(limits, chunk_size);
 632         blk_limits_io_opt(limits, chunk_size * (conf->raid_disks - conf->max_degraded));
 633 }
 634
 635 static void raid_presuspend(struct dm_target *ti)
 636 {
 637         struct raid_set *rs = ti->private;
 638
 639         md_stop_writes(&rs->md);
 640 }
 641
 642 static void raid_postsuspend(struct dm_target *ti)
 643 {
 644         struct raid_set *rs = ti->private;
 645
 646         mddev_suspend(&rs->md);
 647 }
 648
 649 static void raid_resume(struct dm_target *ti)
 650 {
 651         struct raid_set *rs = ti->private;
 652
 653         mddev_resume(&rs->md);
 654 }
 655
 656 static struct target_type raid_target = {
 657         .name = "raid",
 658         .version = {1, 0, 0},
 659         .module = THIS_MODULE,
 660         .ctr = raid_ctr,
 661         .dtr = raid_dtr,
 662         .map = raid_map,
 663         .status = raid_status,
 664         .iterate_devices = raid_iterate_devices,
 665         .io_hints = raid_io_hints,
 666         .presuspend = raid_presuspend,
 667         .postsuspend = raid_postsuspend,
 668         .resume = raid_resume,
 669 };
 670
 671 static int __init dm_raid_init(void)
 672 {
 673         return dm_register_target(&raid_target);
 674 }
 675
 676 static void __exit dm_raid_exit(void)
 677 {
 678         dm_unregister_target(&raid_target);
 679 }
 680
 681 module_init(dm_raid_init);
 682 module_exit(dm_raid_exit);
 683
 684 MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
 685 MODULE_ALIAS("dm-raid4");
 686 MODULE_ALIAS("dm-raid5");
 687 MODULE_ALIAS("dm-raid6");
 688 MODULE_AUTHOR("Neil Brown <dm-devel@redhat.com>");
 689 MODULE_LICENSE("GPL");