drivers/md/raid0.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3    raid0.c : Multiple Devices driver for Linux
   4              Copyright (C) 1994-96 Marc ZYNGIER
   5              <zyngier@ufr-info-p7.ibp.fr> or
   6              <maz@gloups.fdn.fr>
   7              Copyright (C) 1999, 2000 Ingo Molnar, Red Hat
   8
   9    RAID-0 management functions.
  10
  11 */
  12
  13 #include <linux/blkdev.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <trace/events/block.h>
  18 #include "md.h"
  19 #include "raid0.h"
  20 #include "raid5.h"
  21
  22 #define UNSUPPORTED_MDDEV_FLAGS         \
  23         ((1L << MD_HAS_JOURNAL) |       \
  24          (1L << MD_JOURNAL_CLEAN) |     \
  25          (1L << MD_FAILFAST_SUPPORTED) |\
  26          (1L << MD_HAS_PPL) |           \
  27          (1L << MD_HAS_MULTIPLE_PPLS))
  28
  29 static int raid0_congested(struct mddev *mddev, int bits)
  30 {
  31         struct r0conf *conf = mddev->private;
  32         struct md_rdev **devlist = conf->devlist;
  33         int raid_disks = conf->strip_zone[0].nb_dev;
  34         int i, ret = 0;
  35
  36         for (i = 0; i < raid_disks && !ret ; i++) {
  37                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  38
  39                 ret |= bdi_congested(q->backing_dev_info, bits);
  40         }
  41         return ret;
  42 }
  43
  44 /*
  45  * inform the user of the raid configuration
  46 */
  47 static void dump_zones(struct mddev *mddev)
  48 {
  49         int j, k;
  50         sector_t zone_size = 0;
  51         sector_t zone_start = 0;
  52         char b[BDEVNAME_SIZE];
  53         struct r0conf *conf = mddev->private;
  54         int raid_disks = conf->strip_zone[0].nb_dev;
  55         pr_debug("md: RAID0 configuration for %s - %d zone%s\n",
  56                  mdname(mddev),
  57                  conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
  58         for (j = 0; j < conf->nr_strip_zones; j++) {
  59                 char line[200];
  60                 int len = 0;
  61
  62                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
  63                         len += snprintf(line+len, 200-len, "%s%s", k?"/":"",
  64                                         bdevname(conf->devlist[j*raid_disks
  65                                                                + k]->bdev, b));
  66                 pr_debug("md: zone%d=[%s]\n", j, line);
  67
  68                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
  69                 pr_debug("      zone-offset=%10lluKB, device-offset=%10lluKB, size=%10lluKB\n",
  70                         (unsigned long long)zone_start>>1,
  71                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
  72                         (unsigned long long)zone_size>>1);
  73                 zone_start = conf->strip_zone[j].zone_end;
  74         }
  75 }
  76
  77 static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
  78 {
  79         int i, c, err;
  80         sector_t curr_zone_end, sectors;
  81         struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
  82         struct strip_zone *zone;
  83         int cnt;
  84         char b[BDEVNAME_SIZE];
  85         char b2[BDEVNAME_SIZE];
  86         struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
  87         unsigned short blksize = 512;
  88
  89         *private_conf = ERR_PTR(-ENOMEM);
  90         if (!conf)
  91                 return -ENOMEM;
  92         rdev_for_each(rdev1, mddev) {
  93                 pr_debug("md/raid0:%s: looking at %s\n",
  94                          mdname(mddev),
  95                          bdevname(rdev1->bdev, b));
  96                 c = 0;
  97
  98                 /* round size to chunk_size */
  99                 sectors = rdev1->sectors;
 100                 sector_div(sectors, mddev->chunk_sectors);
 101                 rdev1->sectors = sectors * mddev->chunk_sectors;
 102
 103                 blksize = max(blksize, queue_logical_block_size(
 104                                       rdev1->bdev->bd_disk->queue));
 105
 106                 rdev_for_each(rdev2, mddev) {
 107                         pr_debug("md/raid0:%s:   comparing %s(%llu)"
 108                                  " with %s(%llu)\n",
 109                                  mdname(mddev),
 110                                  bdevname(rdev1->bdev,b),
 111                                  (unsigned long long)rdev1->sectors,
 112                                  bdevname(rdev2->bdev,b2),
 113                                  (unsigned long long)rdev2->sectors);
 114                         if (rdev2 == rdev1) {
 115                                 pr_debug("md/raid0:%s:   END\n",
 116                                          mdname(mddev));
 117                                 break;
 118                         }
 119                         if (rdev2->sectors == rdev1->sectors) {
 120                                 /*
 121                                  * Not unique, don't count it as a new
 122                                  * group
 123                                  */
 124                                 pr_debug("md/raid0:%s:   EQUAL\n",
 125                                          mdname(mddev));
 126                                 c = 1;
 127                                 break;
 128                         }
 129                         pr_debug("md/raid0:%s:   NOT EQUAL\n",
 130                                  mdname(mddev));
 131                 }
 132                 if (!c) {
 133                         pr_debug("md/raid0:%s:   ==> UNIQUE\n",
 134                                  mdname(mddev));
 135                         conf->nr_strip_zones++;
 136                         pr_debug("md/raid0:%s: %d zones\n",
 137                                  mdname(mddev), conf->nr_strip_zones);
 138                 }
 139         }
 140         pr_debug("md/raid0:%s: FINAL %d zones\n",
 141                  mdname(mddev), conf->nr_strip_zones);
 142         /*
 143          * now since we have the hard sector sizes, we can make sure
 144          * chunk size is a multiple of that sector size
 145          */
 146         if ((mddev->chunk_sectors << 9) % blksize) {
 147                 pr_warn("md/raid0:%s: chunk_size of %d not multiple of block size %d\n",
 148                         mdname(mddev),
 149                         mddev->chunk_sectors << 9, blksize);
 150                 err = -EINVAL;
 151                 goto abort;
 152         }
 153
 154         err = -ENOMEM;
 155         conf->strip_zone = kcalloc(conf->nr_strip_zones,
 156                                    sizeof(struct strip_zone),
 157                                    GFP_KERNEL);
 158         if (!conf->strip_zone)
 159                 goto abort;
 160         conf->devlist = kzalloc(array3_size(sizeof(struct md_rdev *),
 161                                             conf->nr_strip_zones,
 162                                             mddev->raid_disks),
 163                                 GFP_KERNEL);
 164         if (!conf->devlist)
 165                 goto abort;
 166
 167         /* The first zone must contain all devices, so here we check that
 168          * there is a proper alignment of slots to devices and find them all
 169          */
 170         zone = &conf->strip_zone[0];
 171         cnt = 0;
 172         smallest = NULL;
 173         dev = conf->devlist;
 174         err = -EINVAL;
 175         rdev_for_each(rdev1, mddev) {
 176                 int j = rdev1->raid_disk;
 177
 178                 if (mddev->level == 10) {
 179                         /* taking over a raid10-n2 array */
 180                         j /= 2;
 181                         rdev1->new_raid_disk = j;
 182                 }
 183
 184                 if (mddev->level == 1) {
 185                         /* taiking over a raid1 array-
 186                          * we have only one active disk
 187                          */
 188                         j = 0;
 189                         rdev1->new_raid_disk = j;
 190                 }
 191
 192                 if (j < 0) {
 193                         pr_warn("md/raid0:%s: remove inactive devices before converting to RAID0\n",
 194                                 mdname(mddev));
 195                         goto abort;
 196                 }
 197                 if (j >= mddev->raid_disks) {
 198                         pr_warn("md/raid0:%s: bad disk number %d - aborting!\n",
 199                                 mdname(mddev), j);
 200                         goto abort;
 201                 }
 202                 if (dev[j]) {
 203                         pr_warn("md/raid0:%s: multiple devices for %d - aborting!\n",
 204                                 mdname(mddev), j);
 205                         goto abort;
 206                 }
 207                 dev[j] = rdev1;
 208
 209                 if (!smallest || (rdev1->sectors < smallest->sectors))
 210                         smallest = rdev1;
 211                 cnt++;
 212         }
 213         if (cnt != mddev->raid_disks) {
 214                 pr_warn("md/raid0:%s: too few disks (%d of %d) - aborting!\n",
 215                         mdname(mddev), cnt, mddev->raid_disks);
 216                 goto abort;
 217         }
 218         zone->nb_dev = cnt;
 219         zone->zone_end = smallest->sectors * cnt;
 220
 221         curr_zone_end = zone->zone_end;
 222
 223         /* now do the other zones */
 224         for (i = 1; i < conf->nr_strip_zones; i++)
 225         {
 226                 int j;
 227
 228                 zone = conf->strip_zone + i;
 229                 dev = conf->devlist + i * mddev->raid_disks;
 230
 231                 pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
 232                 zone->dev_start = smallest->sectors;
 233                 smallest = NULL;
 234                 c = 0;
 235
 236                 for (j=0; j<cnt; j++) {
 237                         rdev = conf->devlist[j];
 238                         if (rdev->sectors <= zone->dev_start) {
 239                                 pr_debug("md/raid0:%s: checking %s ... nope\n",
 240                                          mdname(mddev),
 241                                          bdevname(rdev->bdev, b));
 242                                 continue;
 243                         }
 244                         pr_debug("md/raid0:%s: checking %s ..."
 245                                  " contained as device %d\n",
 246                                  mdname(mddev),
 247                                  bdevname(rdev->bdev, b), c);
 248                         dev[c] = rdev;
 249                         c++;
 250                         if (!smallest || rdev->sectors < smallest->sectors) {
 251                                 smallest = rdev;
 252                                 pr_debug("md/raid0:%s:  (%llu) is smallest!.\n",
 253                                          mdname(mddev),
 254                                          (unsigned long long)rdev->sectors);
 255                         }
 256                 }
 257
 258                 zone->nb_dev = c;
 259                 sectors = (smallest->sectors - zone->dev_start) * c;
 260                 pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
 261                          mdname(mddev),
 262                          zone->nb_dev, (unsigned long long)sectors);
 263
 264                 curr_zone_end += sectors;
 265                 zone->zone_end = curr_zone_end;
 266
 267                 pr_debug("md/raid0:%s: current zone start: %llu\n",
 268                          mdname(mddev),
 269                          (unsigned long long)smallest->sectors);
 270         }
 271
 272         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 273         *private_conf = conf;
 274
 275         return 0;
 276 abort:
 277         kfree(conf->strip_zone);
 278         kfree(conf->devlist);
 279         kfree(conf);
 280         *private_conf = ERR_PTR(err);
 281         return err;
 282 }
 283
 284 /* Find the zone which holds a particular offset
 285  * Update *sectorp to be an offset in that zone
 286  */
 287 static struct strip_zone *find_zone(struct r0conf *conf,
 288                                     sector_t *sectorp)
 289 {
 290         int i;
 291         struct strip_zone *z = conf->strip_zone;
 292         sector_t sector = *sectorp;
 293
 294         for (i = 0; i < conf->nr_strip_zones; i++)
 295                 if (sector < z[i].zone_end) {
 296                         if (i)
 297                                 *sectorp = sector - z[i-1].zone_end;
 298                         return z + i;
 299                 }
 300         BUG();
 301 }
 302
 303 /*
 304  * remaps the bio to the target device. we separate two flows.
 305  * power 2 flow and a general flow for the sake of performance
 306 */
 307 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 308                                 sector_t sector, sector_t *sector_offset)
 309 {
 310         unsigned int sect_in_chunk;
 311         sector_t chunk;
 312         struct r0conf *conf = mddev->private;
 313         int raid_disks = conf->strip_zone[0].nb_dev;
 314         unsigned int chunk_sects = mddev->chunk_sectors;
 315
 316         if (is_power_of_2(chunk_sects)) {
 317                 int chunksect_bits = ffz(~chunk_sects);
 318                 /* find the sector offset inside the chunk */
 319                 sect_in_chunk  = sector & (chunk_sects - 1);
 320                 sector >>= chunksect_bits;
 321                 /* chunk in zone */
 322                 chunk = *sector_offset;
 323                 /* quotient is the chunk in real device*/
 324                 sector_div(chunk, zone->nb_dev << chunksect_bits);
 325         } else{
 326                 sect_in_chunk = sector_div(sector, chunk_sects);
 327                 chunk = *sector_offset;
 328                 sector_div(chunk, chunk_sects * zone->nb_dev);
 329         }
 330         /*
 331         *  position the bio over the real device
 332         *  real sector = chunk in device + starting of zone
 333         *       + the position in the chunk
 334         */
 335         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
 336         return conf->devlist[(zone - conf->strip_zone)*raid_disks
 337                              + sector_div(sector, zone->nb_dev)];
 338 }
 339
 340 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 341 {
 342         sector_t array_sectors = 0;
 343         struct md_rdev *rdev;
 344
 345         WARN_ONCE(sectors || raid_disks,
 346                   "%s does not support generic reshape\n", __func__);
 347
 348         rdev_for_each(rdev, mddev)
 349                 array_sectors += (rdev->sectors &
 350                                   ~(sector_t)(mddev->chunk_sectors-1));
 351
 352         return array_sectors;
 353 }
 354
 355 static void raid0_free(struct mddev *mddev, void *priv);
 356
 357 static int raid0_run(struct mddev *mddev)
 358 {
 359         struct r0conf *conf;
 360         int ret;
 361
 362         if (mddev->chunk_sectors == 0) {
 363                 pr_warn("md/raid0:%s: chunk size must be set.\n", mdname(mddev));
 364                 return -EINVAL;
 365         }
 366         if (md_check_no_bitmap(mddev))
 367                 return -EINVAL;
 368
 369         /* if private is not null, we are here after takeover */
 370         if (mddev->private == NULL) {
 371                 ret = create_strip_zones(mddev, &conf);
 372                 if (ret < 0)
 373                         return ret;
 374                 mddev->private = conf;
 375         }
 376         conf = mddev->private;
 377         if (mddev->queue) {
 378                 struct md_rdev *rdev;
 379                 bool discard_supported = false;
 380
 381                 blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 382                 blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 383                 blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
 384                 blk_queue_max_discard_sectors(mddev->queue, UINT_MAX);
 385
 386                 blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 387                 blk_queue_io_opt(mddev->queue,
 388                                  (mddev->chunk_sectors << 9) * mddev->raid_disks);
 389
 390                 rdev_for_each(rdev, mddev) {
 391                         disk_stack_limits(mddev->gendisk, rdev->bdev,
 392                                           rdev->data_offset << 9);
 393                         if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 394                                 discard_supported = true;
 395                 }
 396                 if (!discard_supported)
 397                         blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
 398                 else
 399                         blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
 400         }
 401
 402         /* calculate array device size */
 403         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 404
 405         pr_debug("md/raid0:%s: md_size is %llu sectors.\n",
 406                  mdname(mddev),
 407                  (unsigned long long)mddev->array_sectors);
 408
 409         if (mddev->queue) {
 410                 /* calculate the max read-ahead size.
 411                  * For read-ahead of large files to be effective, we need to
 412                  * readahead at least twice a whole stripe. i.e. number of devices
 413                  * multiplied by chunk size times 2.
 414                  * If an individual device has an ra_pages greater than the
 415                  * chunk size, then we will not drive that device as hard as it
 416                  * wants.  We consider this a configuration error: a larger
 417                  * chunksize should be used in that case.
 418                  */
 419                 int stripe = mddev->raid_disks *
 420                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
 421                 if (mddev->queue->backing_dev_info->ra_pages < 2* stripe)
 422                         mddev->queue->backing_dev_info->ra_pages = 2* stripe;
 423         }
 424
 425         dump_zones(mddev);
 426
 427         ret = md_integrity_register(mddev);
 428
 429         return ret;
 430 }
 431
 432 static void raid0_free(struct mddev *mddev, void *priv)
 433 {
 434         struct r0conf *conf = priv;
 435
 436         kfree(conf->strip_zone);
 437         kfree(conf->devlist);
 438         kfree(conf);
 439 }
 440
 441 /*
 442  * Is io distribute over 1 or more chunks ?
 443 */
 444 static inline int is_io_in_chunk_boundary(struct mddev *mddev,
 445                         unsigned int chunk_sects, struct bio *bio)
 446 {
 447         if (likely(is_power_of_2(chunk_sects))) {
 448                 return chunk_sects >=
 449                         ((bio->bi_iter.bi_sector & (chunk_sects-1))
 450                                         + bio_sectors(bio));
 451         } else{
 452                 sector_t sector = bio->bi_iter.bi_sector;
 453                 return chunk_sects >= (sector_div(sector, chunk_sects)
 454                                                 + bio_sectors(bio));
 455         }
 456 }
 457
 458 static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
 459 {
 460         struct r0conf *conf = mddev->private;
 461         struct strip_zone *zone;
 462         sector_t start = bio->bi_iter.bi_sector;
 463         sector_t end;
 464         unsigned int stripe_size;
 465         sector_t first_stripe_index, last_stripe_index;
 466         sector_t start_disk_offset;
 467         unsigned int start_disk_index;
 468         sector_t end_disk_offset;
 469         unsigned int end_disk_index;
 470         unsigned int disk;
 471
 472         zone = find_zone(conf, &start);
 473
 474         if (bio_end_sector(bio) > zone->zone_end) {
 475                 struct bio *split = bio_split(bio,
 476                         zone->zone_end - bio->bi_iter.bi_sector, GFP_NOIO,
 477                         &mddev->bio_set);
 478                 bio_chain(split, bio);
 479                 generic_make_request(bio);
 480                 bio = split;
 481                 end = zone->zone_end;
 482         } else
 483                 end = bio_end_sector(bio);
 484
 485         if (zone != conf->strip_zone)
 486                 end = end - zone[-1].zone_end;
 487
 488         /* Now start and end is the offset in zone */
 489         stripe_size = zone->nb_dev * mddev->chunk_sectors;
 490
 491         first_stripe_index = start;
 492         sector_div(first_stripe_index, stripe_size);
 493         last_stripe_index = end;
 494         sector_div(last_stripe_index, stripe_size);
 495
 496         start_disk_index = (int)(start - first_stripe_index * stripe_size) /
 497                 mddev->chunk_sectors;
 498         start_disk_offset = ((int)(start - first_stripe_index * stripe_size) %
 499                 mddev->chunk_sectors) +
 500                 first_stripe_index * mddev->chunk_sectors;
 501         end_disk_index = (int)(end - last_stripe_index * stripe_size) /
 502                 mddev->chunk_sectors;
 503         end_disk_offset = ((int)(end - last_stripe_index * stripe_size) %
 504                 mddev->chunk_sectors) +
 505                 last_stripe_index * mddev->chunk_sectors;
 506
 507         for (disk = 0; disk < zone->nb_dev; disk++) {
 508                 sector_t dev_start, dev_end;
 509                 struct bio *discard_bio = NULL;
 510                 struct md_rdev *rdev;
 511
 512                 if (disk < start_disk_index)
 513                         dev_start = (first_stripe_index + 1) *
 514                                 mddev->chunk_sectors;
 515                 else if (disk > start_disk_index)
 516                         dev_start = first_stripe_index * mddev->chunk_sectors;
 517                 else
 518                         dev_start = start_disk_offset;
 519
 520                 if (disk < end_disk_index)
 521                         dev_end = (last_stripe_index + 1) * mddev->chunk_sectors;
 522                 else if (disk > end_disk_index)
 523                         dev_end = last_stripe_index * mddev->chunk_sectors;
 524                 else
 525                         dev_end = end_disk_offset;
 526
 527                 if (dev_end <= dev_start)
 528                         continue;
 529
 530                 rdev = conf->devlist[(zone - conf->strip_zone) *
 531                         conf->strip_zone[0].nb_dev + disk];
 532                 if (__blkdev_issue_discard(rdev->bdev,
 533                         dev_start + zone->dev_start + rdev->data_offset,
 534                         dev_end - dev_start, GFP_NOIO, 0, &discard_bio) ||
 535                     !discard_bio)
 536                         continue;
 537                 bio_chain(discard_bio, bio);
 538                 bio_clone_blkg_association(discard_bio, bio);
 539                 if (mddev->gendisk)
 540                         trace_block_bio_remap(bdev_get_queue(rdev->bdev),
 541                                 discard_bio, disk_devt(mddev->gendisk),
 542                                 bio->bi_iter.bi_sector);
 543                 generic_make_request(discard_bio);
 544         }
 545         bio_endio(bio);
 546 }
 547
 548 static bool raid0_make_request(struct mddev *mddev, struct bio *bio)
 549 {
 550         struct strip_zone *zone;
 551         struct md_rdev *tmp_dev;
 552         sector_t bio_sector;
 553         sector_t sector;
 554         unsigned chunk_sects;
 555         unsigned sectors;
 556
 557         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
 558                 md_flush_request(mddev, bio);
 559                 return true;
 560         }
 561
 562         if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) {
 563                 raid0_handle_discard(mddev, bio);
 564                 return true;
 565         }
 566
 567         bio_sector = bio->bi_iter.bi_sector;
 568         sector = bio_sector;
 569         chunk_sects = mddev->chunk_sectors;
 570
 571         sectors = chunk_sects -
 572                 (likely(is_power_of_2(chunk_sects))
 573                  ? (sector & (chunk_sects-1))
 574                  : sector_div(sector, chunk_sects));
 575
 576         /* Restore due to sector_div */
 577         sector = bio_sector;
 578
 579         if (sectors < bio_sectors(bio)) {
 580                 struct bio *split = bio_split(bio, sectors, GFP_NOIO,
 581                                               &mddev->bio_set);
 582                 bio_chain(split, bio);
 583                 generic_make_request(bio);
 584                 bio = split;
 585         }
 586
 587         zone = find_zone(mddev->private, &sector);
 588         tmp_dev = map_sector(mddev, zone, sector, &sector);
 589         bio_set_dev(bio, tmp_dev->bdev);
 590         bio->bi_iter.bi_sector = sector + zone->dev_start +
 591                 tmp_dev->data_offset;
 592
 593         if (mddev->gendisk)
 594                 trace_block_bio_remap(bio->bi_disk->queue, bio,
 595                                 disk_devt(mddev->gendisk), bio_sector);
 596         mddev_check_writesame(mddev, bio);
 597         mddev_check_write_zeroes(mddev, bio);
 598         generic_make_request(bio);
 599         return true;
 600 }
 601
 602 static void raid0_status(struct seq_file *seq, struct mddev *mddev)
 603 {
 604         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 605         return;
 606 }
 607
 608 static void *raid0_takeover_raid45(struct mddev *mddev)
 609 {
 610         struct md_rdev *rdev;
 611         struct r0conf *priv_conf;
 612
 613         if (mddev->degraded != 1) {
 614                 pr_warn("md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
 615                         mdname(mddev),
 616                         mddev->degraded);
 617                 return ERR_PTR(-EINVAL);
 618         }
 619
 620         rdev_for_each(rdev, mddev) {
 621                 /* check slot number for a disk */
 622                 if (rdev->raid_disk == mddev->raid_disks-1) {
 623                         pr_warn("md/raid0:%s: raid5 must have missing parity disk!\n",
 624                                 mdname(mddev));
 625                         return ERR_PTR(-EINVAL);
 626                 }
 627                 rdev->sectors = mddev->dev_sectors;
 628         }
 629
 630         /* Set new parameters */
 631         mddev->new_level = 0;
 632         mddev->new_layout = 0;
 633         mddev->new_chunk_sectors = mddev->chunk_sectors;
 634         mddev->raid_disks--;
 635         mddev->delta_disks = -1;
 636         /* make sure it will be not marked as dirty */
 637         mddev->recovery_cp = MaxSector;
 638         mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
 639
 640         create_strip_zones(mddev, &priv_conf);
 641
 642         return priv_conf;
 643 }
 644
 645 static void *raid0_takeover_raid10(struct mddev *mddev)
 646 {
 647         struct r0conf *priv_conf;
 648
 649         /* Check layout:
 650          *  - far_copies must be 1
 651          *  - near_copies must be 2
 652          *  - disks number must be even
 653          *  - all mirrors must be already degraded
 654          */
 655         if (mddev->layout != ((1 << 8) + 2)) {
 656                 pr_warn("md/raid0:%s:: Raid0 cannot takeover layout: 0x%x\n",
 657                         mdname(mddev),
 658                         mddev->layout);
 659                 return ERR_PTR(-EINVAL);
 660         }
 661         if (mddev->raid_disks & 1) {
 662                 pr_warn("md/raid0:%s: Raid0 cannot takeover Raid10 with odd disk number.\n",
 663                         mdname(mddev));
 664                 return ERR_PTR(-EINVAL);
 665         }
 666         if (mddev->degraded != (mddev->raid_disks>>1)) {
 667                 pr_warn("md/raid0:%s: All mirrors must be already degraded!\n",
 668                         mdname(mddev));
 669                 return ERR_PTR(-EINVAL);
 670         }
 671
 672         /* Set new parameters */
 673         mddev->new_level = 0;
 674         mddev->new_layout = 0;
 675         mddev->new_chunk_sectors = mddev->chunk_sectors;
 676         mddev->delta_disks = - mddev->raid_disks / 2;
 677         mddev->raid_disks += mddev->delta_disks;
 678         mddev->degraded = 0;
 679         /* make sure it will be not marked as dirty */
 680         mddev->recovery_cp = MaxSector;
 681         mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
 682
 683         create_strip_zones(mddev, &priv_conf);
 684         return priv_conf;
 685 }
 686
 687 static void *raid0_takeover_raid1(struct mddev *mddev)
 688 {
 689         struct r0conf *priv_conf;
 690         int chunksect;
 691
 692         /* Check layout:
 693          *  - (N - 1) mirror drives must be already faulty
 694          */
 695         if ((mddev->raid_disks - 1) != mddev->degraded) {
 696                 pr_err("md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
 697                        mdname(mddev));
 698                 return ERR_PTR(-EINVAL);
 699         }
 700
 701         /*
 702          * a raid1 doesn't have the notion of chunk size, so
 703          * figure out the largest suitable size we can use.
 704          */
 705         chunksect = 64 * 2; /* 64K by default */
 706
 707         /* The array must be an exact multiple of chunksize */
 708         while (chunksect && (mddev->array_sectors & (chunksect - 1)))
 709                 chunksect >>= 1;
 710
 711         if ((chunksect << 9) < PAGE_SIZE)
 712                 /* array size does not allow a suitable chunk size */
 713                 return ERR_PTR(-EINVAL);
 714
 715         /* Set new parameters */
 716         mddev->new_level = 0;
 717         mddev->new_layout = 0;
 718         mddev->new_chunk_sectors = chunksect;
 719         mddev->chunk_sectors = chunksect;
 720         mddev->delta_disks = 1 - mddev->raid_disks;
 721         mddev->raid_disks = 1;
 722         /* make sure it will be not marked as dirty */
 723         mddev->recovery_cp = MaxSector;
 724         mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
 725
 726         create_strip_zones(mddev, &priv_conf);
 727         return priv_conf;
 728 }
 729
 730 static void *raid0_takeover(struct mddev *mddev)
 731 {
 732         /* raid0 can take over:
 733          *  raid4 - if all data disks are active.
 734          *  raid5 - providing it is Raid4 layout and one disk is faulty
 735          *  raid10 - assuming we have all necessary active disks
 736          *  raid1 - with (N -1) mirror drives faulty
 737          */
 738
 739         if (mddev->bitmap) {
 740                 pr_warn("md/raid0: %s: cannot takeover array with bitmap\n",
 741                         mdname(mddev));
 742                 return ERR_PTR(-EBUSY);
 743         }
 744         if (mddev->level == 4)
 745                 return raid0_takeover_raid45(mddev);
 746
 747         if (mddev->level == 5) {
 748                 if (mddev->layout == ALGORITHM_PARITY_N)
 749                         return raid0_takeover_raid45(mddev);
 750
 751                 pr_warn("md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
 752                         mdname(mddev), ALGORITHM_PARITY_N);
 753         }
 754
 755         if (mddev->level == 10)
 756                 return raid0_takeover_raid10(mddev);
 757
 758         if (mddev->level == 1)
 759                 return raid0_takeover_raid1(mddev);
 760
 761         pr_warn("Takeover from raid%i to raid0 not supported\n",
 762                 mddev->level);
 763
 764         return ERR_PTR(-EINVAL);
 765 }
 766
 767 static void raid0_quiesce(struct mddev *mddev, int quiesce)
 768 {
 769 }
 770
 771 static struct md_personality raid0_personality=
 772 {
 773         .name           = "raid0",
 774         .level          = 0,
 775         .owner          = THIS_MODULE,
 776         .make_request   = raid0_make_request,
 777         .run            = raid0_run,
 778         .free           = raid0_free,
 779         .status         = raid0_status,
 780         .size           = raid0_size,
 781         .takeover       = raid0_takeover,
 782         .quiesce        = raid0_quiesce,
 783         .congested      = raid0_congested,
 784 };
 785
 786 static int __init raid0_init (void)
 787 {
 788         return register_md_personality (&raid0_personality);
 789 }
 790
 791 static void raid0_exit (void)
 792 {
 793         unregister_md_personality (&raid0_personality);
 794 }
 795
 796 module_init(raid0_init);
 797 module_exit(raid0_exit);
 798 MODULE_LICENSE("GPL");
 799 MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
 800 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 801 MODULE_ALIAS("md-raid0");
 802 MODULE_ALIAS("md-level-0");