drivers/md/raid0.c

   1 /*
   2    raid0.c : Multiple Devices driver for Linux
   3              Copyright (C) 1994-96 Marc ZYNGIER
   4              <zyngier@ufr-info-p7.ibp.fr> or
   5              <maz@gloups.fdn.fr>
   6              Copyright (C) 1999, 2000 Ingo Molnar, Red Hat
   7
   8    RAID-0 management functions.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2, or (at your option)
  13    any later version.
  14
  15    You should have received a copy of the GNU General Public License
  16    (for example /usr/src/linux/COPYING); if not, write to the Free
  17    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18 */
  19
  20 #include <linux/blkdev.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/module.h>
  23 #include <linux/slab.h>
  24 #include <trace/events/block.h>
  25 #include "md.h"
  26 #include "raid0.h"
  27 #include "raid5.h"
  28
  29 #define UNSUPPORTED_MDDEV_FLAGS         \
  30         ((1L << MD_HAS_JOURNAL) |       \
  31          (1L << MD_JOURNAL_CLEAN) |     \
  32          (1L << MD_FAILFAST_SUPPORTED) |\
  33          (1L << MD_HAS_PPL) |           \
  34          (1L << MD_HAS_MULTIPLE_PPLS))
  35
  36 static int raid0_congested(struct mddev *mddev, int bits)
  37 {
  38         struct r0conf *conf = mddev->private;
  39         struct md_rdev **devlist = conf->devlist;
  40         int raid_disks = conf->strip_zone[0].nb_dev;
  41         int i, ret = 0;
  42
  43         for (i = 0; i < raid_disks && !ret ; i++) {
  44                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  45
  46                 ret |= bdi_congested(q->backing_dev_info, bits);
  47         }
  48         return ret;
  49 }
  50
  51 /*
  52  * inform the user of the raid configuration
  53 */
  54 static void dump_zones(struct mddev *mddev)
  55 {
  56         int j, k;
  57         sector_t zone_size = 0;
  58         sector_t zone_start = 0;
  59         char b[BDEVNAME_SIZE];
  60         struct r0conf *conf = mddev->private;
  61         int raid_disks = conf->strip_zone[0].nb_dev;
  62         pr_debug("md: RAID0 configuration for %s - %d zone%s\n",
  63                  mdname(mddev),
  64                  conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
  65         for (j = 0; j < conf->nr_strip_zones; j++) {
  66                 char line[200];
  67                 int len = 0;
  68
  69                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
  70                         len += snprintf(line+len, 200-len, "%s%s", k?"/":"",
  71                                         bdevname(conf->devlist[j*raid_disks
  72                                                                + k]->bdev, b));
  73                 pr_debug("md: zone%d=[%s]\n", j, line);
  74
  75                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
  76                 pr_debug("      zone-offset=%10lluKB, device-offset=%10lluKB, size=%10lluKB\n",
  77                         (unsigned long long)zone_start>>1,
  78                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
  79                         (unsigned long long)zone_size>>1);
  80                 zone_start = conf->strip_zone[j].zone_end;
  81         }
  82 }
  83
  84 static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
  85 {
  86         int i, c, err;
  87         sector_t curr_zone_end, sectors;
  88         struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
  89         struct strip_zone *zone;
  90         int cnt;
  91         char b[BDEVNAME_SIZE];
  92         char b2[BDEVNAME_SIZE];
  93         struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
  94         unsigned short blksize = 512;
  95
  96         *private_conf = ERR_PTR(-ENOMEM);
  97         if (!conf)
  98                 return -ENOMEM;
  99         rdev_for_each(rdev1, mddev) {
 100                 pr_debug("md/raid0:%s: looking at %s\n",
 101                          mdname(mddev),
 102                          bdevname(rdev1->bdev, b));
 103                 c = 0;
 104
 105                 /* round size to chunk_size */
 106                 sectors = rdev1->sectors;
 107                 sector_div(sectors, mddev->chunk_sectors);
 108                 rdev1->sectors = sectors * mddev->chunk_sectors;
 109
 110                 blksize = max(blksize, queue_logical_block_size(
 111                                       rdev1->bdev->bd_disk->queue));
 112
 113                 rdev_for_each(rdev2, mddev) {
 114                         pr_debug("md/raid0:%s:   comparing %s(%llu)"
 115                                  " with %s(%llu)\n",
 116                                  mdname(mddev),
 117                                  bdevname(rdev1->bdev,b),
 118                                  (unsigned long long)rdev1->sectors,
 119                                  bdevname(rdev2->bdev,b2),
 120                                  (unsigned long long)rdev2->sectors);
 121                         if (rdev2 == rdev1) {
 122                                 pr_debug("md/raid0:%s:   END\n",
 123                                          mdname(mddev));
 124                                 break;
 125                         }
 126                         if (rdev2->sectors == rdev1->sectors) {
 127                                 /*
 128                                  * Not unique, don't count it as a new
 129                                  * group
 130                                  */
 131                                 pr_debug("md/raid0:%s:   EQUAL\n",
 132                                          mdname(mddev));
 133                                 c = 1;
 134                                 break;
 135                         }
 136                         pr_debug("md/raid0:%s:   NOT EQUAL\n",
 137                                  mdname(mddev));
 138                 }
 139                 if (!c) {
 140                         pr_debug("md/raid0:%s:   ==> UNIQUE\n",
 141                                  mdname(mddev));
 142                         conf->nr_strip_zones++;
 143                         pr_debug("md/raid0:%s: %d zones\n",
 144                                  mdname(mddev), conf->nr_strip_zones);
 145                 }
 146         }
 147         pr_debug("md/raid0:%s: FINAL %d zones\n",
 148                  mdname(mddev), conf->nr_strip_zones);
 149         /*
 150          * now since we have the hard sector sizes, we can make sure
 151          * chunk size is a multiple of that sector size
 152          */
 153         if ((mddev->chunk_sectors << 9) % blksize) {
 154                 pr_warn("md/raid0:%s: chunk_size of %d not multiple of block size %d\n",
 155                         mdname(mddev),
 156                         mddev->chunk_sectors << 9, blksize);
 157                 err = -EINVAL;
 158                 goto abort;
 159         }
 160
 161         err = -ENOMEM;
 162         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 163                                 conf->nr_strip_zones, GFP_KERNEL);
 164         if (!conf->strip_zone)
 165                 goto abort;
 166         conf->devlist = kzalloc(sizeof(struct md_rdev*)*
 167                                 conf->nr_strip_zones*mddev->raid_disks,
 168                                 GFP_KERNEL);
 169         if (!conf->devlist)
 170                 goto abort;
 171
 172         /* The first zone must contain all devices, so here we check that
 173          * there is a proper alignment of slots to devices and find them all
 174          */
 175         zone = &conf->strip_zone[0];
 176         cnt = 0;
 177         smallest = NULL;
 178         dev = conf->devlist;
 179         err = -EINVAL;
 180         rdev_for_each(rdev1, mddev) {
 181                 int j = rdev1->raid_disk;
 182
 183                 if (mddev->level == 10) {
 184                         /* taking over a raid10-n2 array */
 185                         j /= 2;
 186                         rdev1->new_raid_disk = j;
 187                 }
 188
 189                 if (mddev->level == 1) {
 190                         /* taiking over a raid1 array-
 191                          * we have only one active disk
 192                          */
 193                         j = 0;
 194                         rdev1->new_raid_disk = j;
 195                 }
 196
 197                 if (j < 0) {
 198                         pr_warn("md/raid0:%s: remove inactive devices before converting to RAID0\n",
 199                                 mdname(mddev));
 200                         goto abort;
 201                 }
 202                 if (j >= mddev->raid_disks) {
 203                         pr_warn("md/raid0:%s: bad disk number %d - aborting!\n",
 204                                 mdname(mddev), j);
 205                         goto abort;
 206                 }
 207                 if (dev[j]) {
 208                         pr_warn("md/raid0:%s: multiple devices for %d - aborting!\n",
 209                                 mdname(mddev), j);
 210                         goto abort;
 211                 }
 212                 dev[j] = rdev1;
 213
 214                 if (!smallest || (rdev1->sectors < smallest->sectors))
 215                         smallest = rdev1;
 216                 cnt++;
 217         }
 218         if (cnt != mddev->raid_disks) {
 219                 pr_warn("md/raid0:%s: too few disks (%d of %d) - aborting!\n",
 220                         mdname(mddev), cnt, mddev->raid_disks);
 221                 goto abort;
 222         }
 223         zone->nb_dev = cnt;
 224         zone->zone_end = smallest->sectors * cnt;
 225
 226         curr_zone_end = zone->zone_end;
 227
 228         /* now do the other zones */
 229         for (i = 1; i < conf->nr_strip_zones; i++)
 230         {
 231                 int j;
 232
 233                 zone = conf->strip_zone + i;
 234                 dev = conf->devlist + i * mddev->raid_disks;
 235
 236                 pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
 237                 zone->dev_start = smallest->sectors;
 238                 smallest = NULL;
 239                 c = 0;
 240
 241                 for (j=0; j<cnt; j++) {
 242                         rdev = conf->devlist[j];
 243                         if (rdev->sectors <= zone->dev_start) {
 244                                 pr_debug("md/raid0:%s: checking %s ... nope\n",
 245                                          mdname(mddev),
 246                                          bdevname(rdev->bdev, b));
 247                                 continue;
 248                         }
 249                         pr_debug("md/raid0:%s: checking %s ..."
 250                                  " contained as device %d\n",
 251                                  mdname(mddev),
 252                                  bdevname(rdev->bdev, b), c);
 253                         dev[c] = rdev;
 254                         c++;
 255                         if (!smallest || rdev->sectors < smallest->sectors) {
 256                                 smallest = rdev;
 257                                 pr_debug("md/raid0:%s:  (%llu) is smallest!.\n",
 258                                          mdname(mddev),
 259                                          (unsigned long long)rdev->sectors);
 260                         }
 261                 }
 262
 263                 zone->nb_dev = c;
 264                 sectors = (smallest->sectors - zone->dev_start) * c;
 265                 pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
 266                          mdname(mddev),
 267                          zone->nb_dev, (unsigned long long)sectors);
 268
 269                 curr_zone_end += sectors;
 270                 zone->zone_end = curr_zone_end;
 271
 272                 pr_debug("md/raid0:%s: current zone start: %llu\n",
 273                          mdname(mddev),
 274                          (unsigned long long)smallest->sectors);
 275         }
 276
 277         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 278         *private_conf = conf;
 279
 280         return 0;
 281 abort:
 282         kfree(conf->strip_zone);
 283         kfree(conf->devlist);
 284         kfree(conf);
 285         *private_conf = ERR_PTR(err);
 286         return err;
 287 }
 288
 289 /* Find the zone which holds a particular offset
 290  * Update *sectorp to be an offset in that zone
 291  */
 292 static struct strip_zone *find_zone(struct r0conf *conf,
 293                                     sector_t *sectorp)
 294 {
 295         int i;
 296         struct strip_zone *z = conf->strip_zone;
 297         sector_t sector = *sectorp;
 298
 299         for (i = 0; i < conf->nr_strip_zones; i++)
 300                 if (sector < z[i].zone_end) {
 301                         if (i)
 302                                 *sectorp = sector - z[i-1].zone_end;
 303                         return z + i;
 304                 }
 305         BUG();
 306 }
 307
 308 /*
 309  * remaps the bio to the target device. we separate two flows.
 310  * power 2 flow and a general flow for the sake of performance
 311 */
 312 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 313                                 sector_t sector, sector_t *sector_offset)
 314 {
 315         unsigned int sect_in_chunk;
 316         sector_t chunk;
 317         struct r0conf *conf = mddev->private;
 318         int raid_disks = conf->strip_zone[0].nb_dev;
 319         unsigned int chunk_sects = mddev->chunk_sectors;
 320
 321         if (is_power_of_2(chunk_sects)) {
 322                 int chunksect_bits = ffz(~chunk_sects);
 323                 /* find the sector offset inside the chunk */
 324                 sect_in_chunk  = sector & (chunk_sects - 1);
 325                 sector >>= chunksect_bits;
 326                 /* chunk in zone */
 327                 chunk = *sector_offset;
 328                 /* quotient is the chunk in real device*/
 329                 sector_div(chunk, zone->nb_dev << chunksect_bits);
 330         } else{
 331                 sect_in_chunk = sector_div(sector, chunk_sects);
 332                 chunk = *sector_offset;
 333                 sector_div(chunk, chunk_sects * zone->nb_dev);
 334         }
 335         /*
 336         *  position the bio over the real device
 337         *  real sector = chunk in device + starting of zone
 338         *       + the position in the chunk
 339         */
 340         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
 341         return conf->devlist[(zone - conf->strip_zone)*raid_disks
 342                              + sector_div(sector, zone->nb_dev)];
 343 }
 344
 345 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 346 {
 347         sector_t array_sectors = 0;
 348         struct md_rdev *rdev;
 349
 350         WARN_ONCE(sectors || raid_disks,
 351                   "%s does not support generic reshape\n", __func__);
 352
 353         rdev_for_each(rdev, mddev)
 354                 array_sectors += (rdev->sectors &
 355                                   ~(sector_t)(mddev->chunk_sectors-1));
 356
 357         return array_sectors;
 358 }
 359
 360 static void raid0_free(struct mddev *mddev, void *priv);
 361
 362 static int raid0_run(struct mddev *mddev)
 363 {
 364         struct r0conf *conf;
 365         int ret;
 366
 367         if (mddev->chunk_sectors == 0) {
 368                 pr_warn("md/raid0:%s: chunk size must be set.\n", mdname(mddev));
 369                 return -EINVAL;
 370         }
 371         if (md_check_no_bitmap(mddev))
 372                 return -EINVAL;
 373
 374         /* if private is not null, we are here after takeover */
 375         if (mddev->private == NULL) {
 376                 ret = create_strip_zones(mddev, &conf);
 377                 if (ret < 0)
 378                         return ret;
 379                 mddev->private = conf;
 380         }
 381         conf = mddev->private;
 382         if (mddev->queue) {
 383                 struct md_rdev *rdev;
 384                 bool discard_supported = false;
 385
 386                 blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 387                 blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 388                 blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
 389                 blk_queue_max_discard_sectors(mddev->queue, UINT_MAX);
 390
 391                 blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 392                 blk_queue_io_opt(mddev->queue,
 393                                  (mddev->chunk_sectors << 9) * mddev->raid_disks);
 394
 395                 rdev_for_each(rdev, mddev) {
 396                         disk_stack_limits(mddev->gendisk, rdev->bdev,
 397                                           rdev->data_offset << 9);
 398                         if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 399                                 discard_supported = true;
 400                 }
 401                 if (!discard_supported)
 402                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 403                 else
 404                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 405         }
 406
 407         /* calculate array device size */
 408         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 409
 410         pr_debug("md/raid0:%s: md_size is %llu sectors.\n",
 411                  mdname(mddev),
 412                  (unsigned long long)mddev->array_sectors);
 413
 414         if (mddev->queue) {
 415                 /* calculate the max read-ahead size.
 416                  * For read-ahead of large files to be effective, we need to
 417                  * readahead at least twice a whole stripe. i.e. number of devices
 418                  * multiplied by chunk size times 2.
 419                  * If an individual device has an ra_pages greater than the
 420                  * chunk size, then we will not drive that device as hard as it
 421                  * wants.  We consider this a configuration error: a larger
 422                  * chunksize should be used in that case.
 423                  */
 424                 int stripe = mddev->raid_disks *
 425                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
 426                 if (mddev->queue->backing_dev_info->ra_pages < 2* stripe)
 427                         mddev->queue->backing_dev_info->ra_pages = 2* stripe;
 428         }
 429
 430         dump_zones(mddev);
 431
 432         ret = md_integrity_register(mddev);
 433
 434         return ret;
 435 }
 436
 437 static void raid0_free(struct mddev *mddev, void *priv)
 438 {
 439         struct r0conf *conf = priv;
 440
 441         kfree(conf->strip_zone);
 442         kfree(conf->devlist);
 443         kfree(conf);
 444 }
 445
 446 /*
 447  * Is io distribute over 1 or more chunks ?
 448 */
 449 static inline int is_io_in_chunk_boundary(struct mddev *mddev,
 450                         unsigned int chunk_sects, struct bio *bio)
 451 {
 452         if (likely(is_power_of_2(chunk_sects))) {
 453                 return chunk_sects >=
 454                         ((bio->bi_iter.bi_sector & (chunk_sects-1))
 455                                         + bio_sectors(bio));
 456         } else{
 457                 sector_t sector = bio->bi_iter.bi_sector;
 458                 return chunk_sects >= (sector_div(sector, chunk_sects)
 459                                                 + bio_sectors(bio));
 460         }
 461 }
 462
 463 static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
 464 {
 465         struct r0conf *conf = mddev->private;
 466         struct strip_zone *zone;
 467         sector_t start = bio->bi_iter.bi_sector;
 468         sector_t end;
 469         unsigned int stripe_size;
 470         sector_t first_stripe_index, last_stripe_index;
 471         sector_t start_disk_offset;
 472         unsigned int start_disk_index;
 473         sector_t end_disk_offset;
 474         unsigned int end_disk_index;
 475         unsigned int disk;
 476
 477         zone = find_zone(conf, &start);
 478
 479         if (bio_end_sector(bio) > zone->zone_end) {
 480                 struct bio *split = bio_split(bio,
 481                         zone->zone_end - bio->bi_iter.bi_sector, GFP_NOIO,
 482                         mddev->bio_set);
 483                 bio_chain(split, bio);
 484                 generic_make_request(bio);
 485                 bio = split;
 486                 end = zone->zone_end;
 487         } else
 488                 end = bio_end_sector(bio);
 489
 490         if (zone != conf->strip_zone)
 491                 end = end - zone[-1].zone_end;
 492
 493         /* Now start and end is the offset in zone */
 494         stripe_size = zone->nb_dev * mddev->chunk_sectors;
 495
 496         first_stripe_index = start;
 497         sector_div(first_stripe_index, stripe_size);
 498         last_stripe_index = end;
 499         sector_div(last_stripe_index, stripe_size);
 500
 501         start_disk_index = (int)(start - first_stripe_index * stripe_size) /
 502                 mddev->chunk_sectors;
 503         start_disk_offset = ((int)(start - first_stripe_index * stripe_size) %
 504                 mddev->chunk_sectors) +
 505                 first_stripe_index * mddev->chunk_sectors;
 506         end_disk_index = (int)(end - last_stripe_index * stripe_size) /
 507                 mddev->chunk_sectors;
 508         end_disk_offset = ((int)(end - last_stripe_index * stripe_size) %
 509                 mddev->chunk_sectors) +
 510                 last_stripe_index * mddev->chunk_sectors;
 511
 512         for (disk = 0; disk < zone->nb_dev; disk++) {
 513                 sector_t dev_start, dev_end;
 514                 struct bio *discard_bio = NULL;
 515                 struct md_rdev *rdev;
 516
 517                 if (disk < start_disk_index)
 518                         dev_start = (first_stripe_index + 1) *
 519                                 mddev->chunk_sectors;
 520                 else if (disk > start_disk_index)
 521                         dev_start = first_stripe_index * mddev->chunk_sectors;
 522                 else
 523                         dev_start = start_disk_offset;
 524
 525                 if (disk < end_disk_index)
 526                         dev_end = (last_stripe_index + 1) * mddev->chunk_sectors;
 527                 else if (disk > end_disk_index)
 528                         dev_end = last_stripe_index * mddev->chunk_sectors;
 529                 else
 530                         dev_end = end_disk_offset;
 531
 532                 if (dev_end <= dev_start)
 533                         continue;
 534
 535                 rdev = conf->devlist[(zone - conf->strip_zone) *
 536                         conf->strip_zone[0].nb_dev + disk];
 537                 if (__blkdev_issue_discard(rdev->bdev,
 538                         dev_start + zone->dev_start + rdev->data_offset,
 539                         dev_end - dev_start, GFP_NOIO, 0, &discard_bio) ||
 540                     !discard_bio)
 541                         continue;
 542                 bio_chain(discard_bio, bio);
 543                 bio_clone_blkcg_association(discard_bio, bio);
 544                 if (mddev->gendisk)
 545                         trace_block_bio_remap(bdev_get_queue(rdev->bdev),
 546                                 discard_bio, disk_devt(mddev->gendisk),
 547                                 bio->bi_iter.bi_sector);
 548                 generic_make_request(discard_bio);
 549         }
 550         bio_endio(bio);
 551 }
 552
 553 static bool raid0_make_request(struct mddev *mddev, struct bio *bio)
 554 {
 555         struct strip_zone *zone;
 556         struct md_rdev *tmp_dev;
 557         sector_t bio_sector;
 558         sector_t sector;
 559         unsigned chunk_sects;
 560         unsigned sectors;
 561
 562         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
 563                 md_flush_request(mddev, bio);
 564                 return true;
 565         }
 566
 567         if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) {
 568                 raid0_handle_discard(mddev, bio);
 569                 return true;
 570         }
 571
 572         bio_sector = bio->bi_iter.bi_sector;
 573         sector = bio_sector;
 574         chunk_sects = mddev->chunk_sectors;
 575
 576         sectors = chunk_sects -
 577                 (likely(is_power_of_2(chunk_sects))
 578                  ? (sector & (chunk_sects-1))
 579                  : sector_div(sector, chunk_sects));
 580
 581         /* Restore due to sector_div */
 582         sector = bio_sector;
 583
 584         if (sectors < bio_sectors(bio)) {
 585                 struct bio *split = bio_split(bio, sectors, GFP_NOIO, mddev->bio_set);
 586                 bio_chain(split, bio);
 587                 generic_make_request(bio);
 588                 bio = split;
 589         }
 590
 591         zone = find_zone(mddev->private, &sector);
 592         tmp_dev = map_sector(mddev, zone, sector, &sector);
 593         bio_set_dev(bio, tmp_dev->bdev);
 594         bio->bi_iter.bi_sector = sector + zone->dev_start +
 595                 tmp_dev->data_offset;
 596
 597         if (mddev->gendisk)
 598                 trace_block_bio_remap(bio->bi_disk->queue, bio,
 599                                 disk_devt(mddev->gendisk), bio_sector);
 600         mddev_check_writesame(mddev, bio);
 601         mddev_check_write_zeroes(mddev, bio);
 602         generic_make_request(bio);
 603         return true;
 604 }
 605
 606 static void raid0_status(struct seq_file *seq, struct mddev *mddev)
 607 {
 608         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 609         return;
 610 }
 611
 612 static void *raid0_takeover_raid45(struct mddev *mddev)
 613 {
 614         struct md_rdev *rdev;
 615         struct r0conf *priv_conf;
 616
 617         if (mddev->degraded != 1) {
 618                 pr_warn("md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
 619                         mdname(mddev),
 620                         mddev->degraded);
 621                 return ERR_PTR(-EINVAL);
 622         }
 623
 624         rdev_for_each(rdev, mddev) {
 625                 /* check slot number for a disk */
 626                 if (rdev->raid_disk == mddev->raid_disks-1) {
 627                         pr_warn("md/raid0:%s: raid5 must have missing parity disk!\n",
 628                                 mdname(mddev));
 629                         return ERR_PTR(-EINVAL);
 630                 }
 631                 rdev->sectors = mddev->dev_sectors;
 632         }
 633
 634         /* Set new parameters */
 635         mddev->new_level = 0;
 636         mddev->new_layout = 0;
 637         mddev->new_chunk_sectors = mddev->chunk_sectors;
 638         mddev->raid_disks--;
 639         mddev->delta_disks = -1;
 640         /* make sure it will be not marked as dirty */
 641         mddev->recovery_cp = MaxSector;
 642         mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
 643
 644         create_strip_zones(mddev, &priv_conf);
 645
 646         return priv_conf;
 647 }
 648
 649 static void *raid0_takeover_raid10(struct mddev *mddev)
 650 {
 651         struct r0conf *priv_conf;
 652
 653         /* Check layout:
 654          *  - far_copies must be 1
 655          *  - near_copies must be 2
 656          *  - disks number must be even
 657          *  - all mirrors must be already degraded
 658          */
 659         if (mddev->layout != ((1 << 8) + 2)) {
 660                 pr_warn("md/raid0:%s:: Raid0 cannot takeover layout: 0x%x\n",
 661                         mdname(mddev),
 662                         mddev->layout);
 663                 return ERR_PTR(-EINVAL);
 664         }
 665         if (mddev->raid_disks & 1) {
 666                 pr_warn("md/raid0:%s: Raid0 cannot takeover Raid10 with odd disk number.\n",
 667                         mdname(mddev));
 668                 return ERR_PTR(-EINVAL);
 669         }
 670         if (mddev->degraded != (mddev->raid_disks>>1)) {
 671                 pr_warn("md/raid0:%s: All mirrors must be already degraded!\n",
 672                         mdname(mddev));
 673                 return ERR_PTR(-EINVAL);
 674         }
 675
 676         /* Set new parameters */
 677         mddev->new_level = 0;
 678         mddev->new_layout = 0;
 679         mddev->new_chunk_sectors = mddev->chunk_sectors;
 680         mddev->delta_disks = - mddev->raid_disks / 2;
 681         mddev->raid_disks += mddev->delta_disks;
 682         mddev->degraded = 0;
 683         /* make sure it will be not marked as dirty */
 684         mddev->recovery_cp = MaxSector;
 685         mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
 686
 687         create_strip_zones(mddev, &priv_conf);
 688         return priv_conf;
 689 }
 690
 691 static void *raid0_takeover_raid1(struct mddev *mddev)
 692 {
 693         struct r0conf *priv_conf;
 694         int chunksect;
 695
 696         /* Check layout:
 697          *  - (N - 1) mirror drives must be already faulty
 698          */
 699         if ((mddev->raid_disks - 1) != mddev->degraded) {
 700                 pr_err("md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
 701                        mdname(mddev));
 702                 return ERR_PTR(-EINVAL);
 703         }
 704
 705         /*
 706          * a raid1 doesn't have the notion of chunk size, so
 707          * figure out the largest suitable size we can use.
 708          */
 709         chunksect = 64 * 2; /* 64K by default */
 710
 711         /* The array must be an exact multiple of chunksize */
 712         while (chunksect && (mddev->array_sectors & (chunksect - 1)))
 713                 chunksect >>= 1;
 714
 715         if ((chunksect << 9) < PAGE_SIZE)
 716                 /* array size does not allow a suitable chunk size */
 717                 return ERR_PTR(-EINVAL);
 718
 719         /* Set new parameters */
 720         mddev->new_level = 0;
 721         mddev->new_layout = 0;
 722         mddev->new_chunk_sectors = chunksect;
 723         mddev->chunk_sectors = chunksect;
 724         mddev->delta_disks = 1 - mddev->raid_disks;
 725         mddev->raid_disks = 1;
 726         /* make sure it will be not marked as dirty */
 727         mddev->recovery_cp = MaxSector;
 728         mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
 729
 730         create_strip_zones(mddev, &priv_conf);
 731         return priv_conf;
 732 }
 733
 734 static void *raid0_takeover(struct mddev *mddev)
 735 {
 736         /* raid0 can take over:
 737          *  raid4 - if all data disks are active.
 738          *  raid5 - providing it is Raid4 layout and one disk is faulty
 739          *  raid10 - assuming we have all necessary active disks
 740          *  raid1 - with (N -1) mirror drives faulty
 741          */
 742
 743         if (mddev->bitmap) {
 744                 pr_warn("md/raid0: %s: cannot takeover array with bitmap\n",
 745                         mdname(mddev));
 746                 return ERR_PTR(-EBUSY);
 747         }
 748         if (mddev->level == 4)
 749                 return raid0_takeover_raid45(mddev);
 750
 751         if (mddev->level == 5) {
 752                 if (mddev->layout == ALGORITHM_PARITY_N)
 753                         return raid0_takeover_raid45(mddev);
 754
 755                 pr_warn("md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
 756                         mdname(mddev), ALGORITHM_PARITY_N);
 757         }
 758
 759         if (mddev->level == 10)
 760                 return raid0_takeover_raid10(mddev);
 761
 762         if (mddev->level == 1)
 763                 return raid0_takeover_raid1(mddev);
 764
 765         pr_warn("Takeover from raid%i to raid0 not supported\n",
 766                 mddev->level);
 767
 768         return ERR_PTR(-EINVAL);
 769 }
 770
 771 static void raid0_quiesce(struct mddev *mddev, int quiesce)
 772 {
 773 }
 774
 775 static struct md_personality raid0_personality=
 776 {
 777         .name           = "raid0",
 778         .level          = 0,
 779         .owner          = THIS_MODULE,
 780         .make_request   = raid0_make_request,
 781         .run            = raid0_run,
 782         .free           = raid0_free,
 783         .status         = raid0_status,
 784         .size           = raid0_size,
 785         .takeover       = raid0_takeover,
 786         .quiesce        = raid0_quiesce,
 787         .congested      = raid0_congested,
 788 };
 789
 790 static int __init raid0_init (void)
 791 {
 792         return register_md_personality (&raid0_personality);
 793 }
 794
 795 static void raid0_exit (void)
 796 {
 797         unregister_md_personality (&raid0_personality);
 798 }
 799
 800 module_init(raid0_init);
 801 module_exit(raid0_exit);
 802 MODULE_LICENSE("GPL");
 803 MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
 804 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 805 MODULE_ALIAS("md-raid0");
 806 MODULE_ALIAS("md-level-0");