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 "md.h"
  25 #include "raid0.h"
  26 #include "raid5.h"
  27
  28 static int raid0_congested(struct mddev *mddev, int bits)
  29 {
  30         struct r0conf *conf = mddev->private;
  31         struct md_rdev **devlist = conf->devlist;
  32         int raid_disks = conf->strip_zone[0].nb_dev;
  33         int i, ret = 0;
  34
  35         for (i = 0; i < raid_disks && !ret ; i++) {
  36                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  37
  38                 ret |= bdi_congested(&q->backing_dev_info, bits);
  39         }
  40         return ret;
  41 }
  42
  43 /*
  44  * inform the user of the raid configuration
  45 */
  46 static void dump_zones(struct mddev *mddev)
  47 {
  48         int j, k;
  49         sector_t zone_size = 0;
  50         sector_t zone_start = 0;
  51         char b[BDEVNAME_SIZE];
  52         struct r0conf *conf = mddev->private;
  53         int raid_disks = conf->strip_zone[0].nb_dev;
  54         printk(KERN_INFO "md: RAID0 configuration for %s - %d zone%s\n",
  55                mdname(mddev),
  56                conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
  57         for (j = 0; j < conf->nr_strip_zones; j++) {
  58                 printk(KERN_INFO "md: zone%d=[", j);
  59                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
  60                         printk(KERN_CONT "%s%s", k?"/":"",
  61                         bdevname(conf->devlist[j*raid_disks
  62                                                 + k]->bdev, b));
  63                 printk(KERN_CONT "]\n");
  64
  65                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
  66                 printk(KERN_INFO "      zone-offset=%10lluKB, "
  67                                 "device-offset=%10lluKB, size=%10lluKB\n",
  68                         (unsigned long long)zone_start>>1,
  69                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
  70                         (unsigned long long)zone_size>>1);
  71                 zone_start = conf->strip_zone[j].zone_end;
  72         }
  73         printk(KERN_INFO "\n");
  74 }
  75
  76 static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
  77 {
  78         int i, c, err;
  79         sector_t curr_zone_end, sectors;
  80         struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
  81         struct strip_zone *zone;
  82         int cnt;
  83         char b[BDEVNAME_SIZE];
  84         char b2[BDEVNAME_SIZE];
  85         struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
  86         bool discard_supported = false;
  87
  88         if (!conf)
  89                 return -ENOMEM;
  90         rdev_for_each(rdev1, mddev) {
  91                 pr_debug("md/raid0:%s: looking at %s\n",
  92                          mdname(mddev),
  93                          bdevname(rdev1->bdev, b));
  94                 c = 0;
  95
  96                 /* round size to chunk_size */
  97                 sectors = rdev1->sectors;
  98                 sector_div(sectors, mddev->chunk_sectors);
  99                 rdev1->sectors = sectors * mddev->chunk_sectors;
 100
 101                 rdev_for_each(rdev2, mddev) {
 102                         pr_debug("md/raid0:%s:   comparing %s(%llu)"
 103                                  " with %s(%llu)\n",
 104                                  mdname(mddev),
 105                                  bdevname(rdev1->bdev,b),
 106                                  (unsigned long long)rdev1->sectors,
 107                                  bdevname(rdev2->bdev,b2),
 108                                  (unsigned long long)rdev2->sectors);
 109                         if (rdev2 == rdev1) {
 110                                 pr_debug("md/raid0:%s:   END\n",
 111                                          mdname(mddev));
 112                                 break;
 113                         }
 114                         if (rdev2->sectors == rdev1->sectors) {
 115                                 /*
 116                                  * Not unique, don't count it as a new
 117                                  * group
 118                                  */
 119                                 pr_debug("md/raid0:%s:   EQUAL\n",
 120                                          mdname(mddev));
 121                                 c = 1;
 122                                 break;
 123                         }
 124                         pr_debug("md/raid0:%s:   NOT EQUAL\n",
 125                                  mdname(mddev));
 126                 }
 127                 if (!c) {
 128                         pr_debug("md/raid0:%s:   ==> UNIQUE\n",
 129                                  mdname(mddev));
 130                         conf->nr_strip_zones++;
 131                         pr_debug("md/raid0:%s: %d zones\n",
 132                                  mdname(mddev), conf->nr_strip_zones);
 133                 }
 134         }
 135         pr_debug("md/raid0:%s: FINAL %d zones\n",
 136                  mdname(mddev), conf->nr_strip_zones);
 137         err = -ENOMEM;
 138         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 139                                 conf->nr_strip_zones, GFP_KERNEL);
 140         if (!conf->strip_zone)
 141                 goto abort;
 142         conf->devlist = kzalloc(sizeof(struct md_rdev*)*
 143                                 conf->nr_strip_zones*mddev->raid_disks,
 144                                 GFP_KERNEL);
 145         if (!conf->devlist)
 146                 goto abort;
 147
 148         /* The first zone must contain all devices, so here we check that
 149          * there is a proper alignment of slots to devices and find them all
 150          */
 151         zone = &conf->strip_zone[0];
 152         cnt = 0;
 153         smallest = NULL;
 154         dev = conf->devlist;
 155         err = -EINVAL;
 156         rdev_for_each(rdev1, mddev) {
 157                 int j = rdev1->raid_disk;
 158
 159                 if (mddev->level == 10) {
 160                         /* taking over a raid10-n2 array */
 161                         j /= 2;
 162                         rdev1->new_raid_disk = j;
 163                 }
 164
 165                 if (mddev->level == 1) {
 166                         /* taiking over a raid1 array-
 167                          * we have only one active disk
 168                          */
 169                         j = 0;
 170                         rdev1->new_raid_disk = j;
 171                 }
 172
 173                 if (j < 0) {
 174                         printk(KERN_ERR
 175                                "md/raid0:%s: remove inactive devices before converting to RAID0\n",
 176                                mdname(mddev));
 177                         goto abort;
 178                 }
 179                 if (j >= mddev->raid_disks) {
 180                         printk(KERN_ERR "md/raid0:%s: bad disk number %d - "
 181                                "aborting!\n", mdname(mddev), j);
 182                         goto abort;
 183                 }
 184                 if (dev[j]) {
 185                         printk(KERN_ERR "md/raid0:%s: multiple devices for %d - "
 186                                "aborting!\n", mdname(mddev), j);
 187                         goto abort;
 188                 }
 189                 dev[j] = rdev1;
 190
 191                 disk_stack_limits(mddev->gendisk, rdev1->bdev,
 192                                   rdev1->data_offset << 9);
 193
 194                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
 195                         conf->has_merge_bvec = 1;
 196
 197                 if (!smallest || (rdev1->sectors < smallest->sectors))
 198                         smallest = rdev1;
 199                 cnt++;
 200
 201                 if (blk_queue_discard(bdev_get_queue(rdev1->bdev)))
 202                         discard_supported = true;
 203         }
 204         if (cnt != mddev->raid_disks) {
 205                 printk(KERN_ERR "md/raid0:%s: too few disks (%d of %d) - "
 206                        "aborting!\n", mdname(mddev), cnt, mddev->raid_disks);
 207                 goto abort;
 208         }
 209         zone->nb_dev = cnt;
 210         zone->zone_end = smallest->sectors * cnt;
 211
 212         curr_zone_end = zone->zone_end;
 213
 214         /* now do the other zones */
 215         for (i = 1; i < conf->nr_strip_zones; i++)
 216         {
 217                 int j;
 218
 219                 zone = conf->strip_zone + i;
 220                 dev = conf->devlist + i * mddev->raid_disks;
 221
 222                 pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
 223                 zone->dev_start = smallest->sectors;
 224                 smallest = NULL;
 225                 c = 0;
 226
 227                 for (j=0; j<cnt; j++) {
 228                         rdev = conf->devlist[j];
 229                         if (rdev->sectors <= zone->dev_start) {
 230                                 pr_debug("md/raid0:%s: checking %s ... nope\n",
 231                                          mdname(mddev),
 232                                          bdevname(rdev->bdev, b));
 233                                 continue;
 234                         }
 235                         pr_debug("md/raid0:%s: checking %s ..."
 236                                  " contained as device %d\n",
 237                                  mdname(mddev),
 238                                  bdevname(rdev->bdev, b), c);
 239                         dev[c] = rdev;
 240                         c++;
 241                         if (!smallest || rdev->sectors < smallest->sectors) {
 242                                 smallest = rdev;
 243                                 pr_debug("md/raid0:%s:  (%llu) is smallest!.\n",
 244                                          mdname(mddev),
 245                                          (unsigned long long)rdev->sectors);
 246                         }
 247                 }
 248
 249                 zone->nb_dev = c;
 250                 sectors = (smallest->sectors - zone->dev_start) * c;
 251                 pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
 252                          mdname(mddev),
 253                          zone->nb_dev, (unsigned long long)sectors);
 254
 255                 curr_zone_end += sectors;
 256                 zone->zone_end = curr_zone_end;
 257
 258                 pr_debug("md/raid0:%s: current zone start: %llu\n",
 259                          mdname(mddev),
 260                          (unsigned long long)smallest->sectors);
 261         }
 262
 263         /*
 264          * now since we have the hard sector sizes, we can make sure
 265          * chunk size is a multiple of that sector size
 266          */
 267         if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
 268                 printk(KERN_ERR "md/raid0:%s: chunk_size of %d not valid\n",
 269                        mdname(mddev),
 270                        mddev->chunk_sectors << 9);
 271                 goto abort;
 272         }
 273
 274         blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 275         blk_queue_io_opt(mddev->queue,
 276                          (mddev->chunk_sectors << 9) * mddev->raid_disks);
 277
 278         if (!discard_supported)
 279                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 280         else
 281                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 282
 283         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 284         *private_conf = conf;
 285
 286         return 0;
 287 abort:
 288         kfree(conf->strip_zone);
 289         kfree(conf->devlist);
 290         kfree(conf);
 291         *private_conf = ERR_PTR(err);
 292         return err;
 293 }
 294
 295 /* Find the zone which holds a particular offset
 296  * Update *sectorp to be an offset in that zone
 297  */
 298 static struct strip_zone *find_zone(struct r0conf *conf,
 299                                     sector_t *sectorp)
 300 {
 301         int i;
 302         struct strip_zone *z = conf->strip_zone;
 303         sector_t sector = *sectorp;
 304
 305         for (i = 0; i < conf->nr_strip_zones; i++)
 306                 if (sector < z[i].zone_end) {
 307                         if (i)
 308                                 *sectorp = sector - z[i-1].zone_end;
 309                         return z + i;
 310                 }
 311         BUG();
 312 }
 313
 314 /*
 315  * remaps the bio to the target device. we separate two flows.
 316  * power 2 flow and a general flow for the sake of perfromance
 317 */
 318 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 319                                 sector_t sector, sector_t *sector_offset)
 320 {
 321         unsigned int sect_in_chunk;
 322         sector_t chunk;
 323         struct r0conf *conf = mddev->private;
 324         int raid_disks = conf->strip_zone[0].nb_dev;
 325         unsigned int chunk_sects = mddev->chunk_sectors;
 326
 327         if (is_power_of_2(chunk_sects)) {
 328                 int chunksect_bits = ffz(~chunk_sects);
 329                 /* find the sector offset inside the chunk */
 330                 sect_in_chunk  = sector & (chunk_sects - 1);
 331                 sector >>= chunksect_bits;
 332                 /* chunk in zone */
 333                 chunk = *sector_offset;
 334                 /* quotient is the chunk in real device*/
 335                 sector_div(chunk, zone->nb_dev << chunksect_bits);
 336         } else{
 337                 sect_in_chunk = sector_div(sector, chunk_sects);
 338                 chunk = *sector_offset;
 339                 sector_div(chunk, chunk_sects * zone->nb_dev);
 340         }
 341         /*
 342         *  position the bio over the real device
 343         *  real sector = chunk in device + starting of zone
 344         *       + the position in the chunk
 345         */
 346         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
 347         return conf->devlist[(zone - conf->strip_zone)*raid_disks
 348                              + sector_div(sector, zone->nb_dev)];
 349 }
 350
 351 /**
 352  *      raid0_mergeable_bvec -- tell bio layer if two requests can be merged
 353  *      @mddev: the md device
 354  *      @bvm: properties of new bio
 355  *      @biovec: the request that could be merged to it.
 356  *
 357  *      Return amount of bytes we can accept at this offset
 358  */
 359 static int raid0_mergeable_bvec(struct mddev *mddev,
 360                                 struct bvec_merge_data *bvm,
 361                                 struct bio_vec *biovec)
 362 {
 363         struct r0conf *conf = mddev->private;
 364         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 365         sector_t sector_offset = sector;
 366         int max;
 367         unsigned int chunk_sectors = mddev->chunk_sectors;
 368         unsigned int bio_sectors = bvm->bi_size >> 9;
 369         struct strip_zone *zone;
 370         struct md_rdev *rdev;
 371         struct request_queue *subq;
 372
 373         if (is_power_of_2(chunk_sectors))
 374                 max =  (chunk_sectors - ((sector & (chunk_sectors-1))
 375                                                 + bio_sectors)) << 9;
 376         else
 377                 max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
 378                                                 + bio_sectors)) << 9;
 379         if (max < 0)
 380                 max = 0; /* bio_add cannot handle a negative return */
 381         if (max <= biovec->bv_len && bio_sectors == 0)
 382                 return biovec->bv_len;
 383         if (max < biovec->bv_len)
 384                 /* too small already, no need to check further */
 385                 return max;
 386         if (!conf->has_merge_bvec)
 387                 return max;
 388
 389         /* May need to check subordinate device */
 390         sector = sector_offset;
 391         zone = find_zone(mddev->private, &sector_offset);
 392         rdev = map_sector(mddev, zone, sector, &sector_offset);
 393         subq = bdev_get_queue(rdev->bdev);
 394         if (subq->merge_bvec_fn) {
 395                 bvm->bi_bdev = rdev->bdev;
 396                 bvm->bi_sector = sector_offset + zone->dev_start +
 397                         rdev->data_offset;
 398                 return min(max, subq->merge_bvec_fn(subq, bvm, biovec));
 399         } else
 400                 return max;
 401 }
 402
 403 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 404 {
 405         sector_t array_sectors = 0;
 406         struct md_rdev *rdev;
 407
 408         WARN_ONCE(sectors || raid_disks,
 409                   "%s does not support generic reshape\n", __func__);
 410
 411         rdev_for_each(rdev, mddev)
 412                 array_sectors += (rdev->sectors &
 413                                   ~(sector_t)(mddev->chunk_sectors-1));
 414
 415         return array_sectors;
 416 }
 417
 418 static void raid0_free(struct mddev *mddev, void *priv);
 419
 420 static int raid0_run(struct mddev *mddev)
 421 {
 422         struct r0conf *conf;
 423         int ret;
 424
 425         if (mddev->chunk_sectors == 0) {
 426                 printk(KERN_ERR "md/raid0:%s: chunk size must be set.\n",
 427                        mdname(mddev));
 428                 return -EINVAL;
 429         }
 430         if (md_check_no_bitmap(mddev))
 431                 return -EINVAL;
 432         blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 433         blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 434         blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
 435
 436         /* if private is not null, we are here after takeover */
 437         if (mddev->private == NULL) {
 438                 ret = create_strip_zones(mddev, &conf);
 439                 if (ret < 0)
 440                         return ret;
 441                 mddev->private = conf;
 442         }
 443         conf = mddev->private;
 444
 445         /* calculate array device size */
 446         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 447
 448         printk(KERN_INFO "md/raid0:%s: md_size is %llu sectors.\n",
 449                mdname(mddev),
 450                (unsigned long long)mddev->array_sectors);
 451         /* calculate the max read-ahead size.
 452          * For read-ahead of large files to be effective, we need to
 453          * readahead at least twice a whole stripe. i.e. number of devices
 454          * multiplied by chunk size times 2.
 455          * If an individual device has an ra_pages greater than the
 456          * chunk size, then we will not drive that device as hard as it
 457          * wants.  We consider this a configuration error: a larger
 458          * chunksize should be used in that case.
 459          */
 460         {
 461                 int stripe = mddev->raid_disks *
 462                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
 463                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 464                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 465         }
 466
 467         dump_zones(mddev);
 468
 469         ret = md_integrity_register(mddev);
 470         if (ret)
 471                 raid0_free(mddev, conf);
 472
 473         return ret;
 474 }
 475
 476 static void raid0_free(struct mddev *mddev, void *priv)
 477 {
 478         struct r0conf *conf = priv;
 479
 480         kfree(conf->strip_zone);
 481         kfree(conf->devlist);
 482         kfree(conf);
 483 }
 484
 485 /*
 486  * Is io distribute over 1 or more chunks ?
 487 */
 488 static inline int is_io_in_chunk_boundary(struct mddev *mddev,
 489                         unsigned int chunk_sects, struct bio *bio)
 490 {
 491         if (likely(is_power_of_2(chunk_sects))) {
 492                 return chunk_sects >=
 493                         ((bio->bi_iter.bi_sector & (chunk_sects-1))
 494                                         + bio_sectors(bio));
 495         } else{
 496                 sector_t sector = bio->bi_iter.bi_sector;
 497                 return chunk_sects >= (sector_div(sector, chunk_sects)
 498                                                 + bio_sectors(bio));
 499         }
 500 }
 501
 502 static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 503 {
 504         struct strip_zone *zone;
 505         struct md_rdev *tmp_dev;
 506         struct bio *split;
 507
 508         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 509                 md_flush_request(mddev, bio);
 510                 return;
 511         }
 512
 513         do {
 514                 sector_t sector = bio->bi_iter.bi_sector;
 515                 unsigned chunk_sects = mddev->chunk_sectors;
 516
 517                 unsigned sectors = chunk_sects -
 518                         (likely(is_power_of_2(chunk_sects))
 519                          ? (sector & (chunk_sects-1))
 520                          : sector_div(sector, chunk_sects));
 521
 522                 if (sectors < bio_sectors(bio)) {
 523                         split = bio_split(bio, sectors, GFP_NOIO, fs_bio_set);
 524                         bio_chain(split, bio);
 525                 } else {
 526                         split = bio;
 527                 }
 528
 529                 zone = find_zone(mddev->private, &sector);
 530                 tmp_dev = map_sector(mddev, zone, sector, &sector);
 531                 split->bi_bdev = tmp_dev->bdev;
 532                 split->bi_iter.bi_sector = sector + zone->dev_start +
 533                         tmp_dev->data_offset;
 534
 535                 if (unlikely((split->bi_rw & REQ_DISCARD) &&
 536                          !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
 537                         /* Just ignore it */
 538                         bio_endio(split, 0);
 539                 } else
 540                         generic_make_request(split);
 541         } while (split != bio);
 542 }
 543
 544 static void raid0_status(struct seq_file *seq, struct mddev *mddev)
 545 {
 546         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 547         return;
 548 }
 549
 550 static void *raid0_takeover_raid45(struct mddev *mddev)
 551 {
 552         struct md_rdev *rdev;
 553         struct r0conf *priv_conf;
 554
 555         if (mddev->degraded != 1) {
 556                 printk(KERN_ERR "md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
 557                        mdname(mddev),
 558                        mddev->degraded);
 559                 return ERR_PTR(-EINVAL);
 560         }
 561
 562         rdev_for_each(rdev, mddev) {
 563                 /* check slot number for a disk */
 564                 if (rdev->raid_disk == mddev->raid_disks-1) {
 565                         printk(KERN_ERR "md/raid0:%s: raid5 must have missing parity disk!\n",
 566                                mdname(mddev));
 567                         return ERR_PTR(-EINVAL);
 568                 }
 569                 rdev->sectors = mddev->dev_sectors;
 570         }
 571
 572         /* Set new parameters */
 573         mddev->new_level = 0;
 574         mddev->new_layout = 0;
 575         mddev->new_chunk_sectors = mddev->chunk_sectors;
 576         mddev->raid_disks--;
 577         mddev->delta_disks = -1;
 578         /* make sure it will be not marked as dirty */
 579         mddev->recovery_cp = MaxSector;
 580
 581         create_strip_zones(mddev, &priv_conf);
 582         return priv_conf;
 583 }
 584
 585 static void *raid0_takeover_raid10(struct mddev *mddev)
 586 {
 587         struct r0conf *priv_conf;
 588
 589         /* Check layout:
 590          *  - far_copies must be 1
 591          *  - near_copies must be 2
 592          *  - disks number must be even
 593          *  - all mirrors must be already degraded
 594          */
 595         if (mddev->layout != ((1 << 8) + 2)) {
 596                 printk(KERN_ERR "md/raid0:%s:: Raid0 cannot takover layout: 0x%x\n",
 597                        mdname(mddev),
 598                        mddev->layout);
 599                 return ERR_PTR(-EINVAL);
 600         }
 601         if (mddev->raid_disks & 1) {
 602                 printk(KERN_ERR "md/raid0:%s: Raid0 cannot takover Raid10 with odd disk number.\n",
 603                        mdname(mddev));
 604                 return ERR_PTR(-EINVAL);
 605         }
 606         if (mddev->degraded != (mddev->raid_disks>>1)) {
 607                 printk(KERN_ERR "md/raid0:%s: All mirrors must be already degraded!\n",
 608                        mdname(mddev));
 609                 return ERR_PTR(-EINVAL);
 610         }
 611
 612         /* Set new parameters */
 613         mddev->new_level = 0;
 614         mddev->new_layout = 0;
 615         mddev->new_chunk_sectors = mddev->chunk_sectors;
 616         mddev->delta_disks = - mddev->raid_disks / 2;
 617         mddev->raid_disks += mddev->delta_disks;
 618         mddev->degraded = 0;
 619         /* make sure it will be not marked as dirty */
 620         mddev->recovery_cp = MaxSector;
 621
 622         create_strip_zones(mddev, &priv_conf);
 623         return priv_conf;
 624 }
 625
 626 static void *raid0_takeover_raid1(struct mddev *mddev)
 627 {
 628         struct r0conf *priv_conf;
 629         int chunksect;
 630
 631         /* Check layout:
 632          *  - (N - 1) mirror drives must be already faulty
 633          */
 634         if ((mddev->raid_disks - 1) != mddev->degraded) {
 635                 printk(KERN_ERR "md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
 636                        mdname(mddev));
 637                 return ERR_PTR(-EINVAL);
 638         }
 639
 640         /*
 641          * a raid1 doesn't have the notion of chunk size, so
 642          * figure out the largest suitable size we can use.
 643          */
 644         chunksect = 64 * 2; /* 64K by default */
 645
 646         /* The array must be an exact multiple of chunksize */
 647         while (chunksect && (mddev->array_sectors & (chunksect - 1)))
 648                 chunksect >>= 1;
 649
 650         if ((chunksect << 9) < PAGE_SIZE)
 651                 /* array size does not allow a suitable chunk size */
 652                 return ERR_PTR(-EINVAL);
 653
 654         /* Set new parameters */
 655         mddev->new_level = 0;
 656         mddev->new_layout = 0;
 657         mddev->new_chunk_sectors = chunksect;
 658         mddev->chunk_sectors = chunksect;
 659         mddev->delta_disks = 1 - mddev->raid_disks;
 660         mddev->raid_disks = 1;
 661         /* make sure it will be not marked as dirty */
 662         mddev->recovery_cp = MaxSector;
 663
 664         create_strip_zones(mddev, &priv_conf);
 665         return priv_conf;
 666 }
 667
 668 static void *raid0_takeover(struct mddev *mddev)
 669 {
 670         /* raid0 can take over:
 671          *  raid4 - if all data disks are active.
 672          *  raid5 - providing it is Raid4 layout and one disk is faulty
 673          *  raid10 - assuming we have all necessary active disks
 674          *  raid1 - with (N -1) mirror drives faulty
 675          */
 676
 677         if (mddev->bitmap) {
 678                 printk(KERN_ERR "md/raid0: %s: cannot takeover array with bitmap\n",
 679                        mdname(mddev));
 680                 return ERR_PTR(-EBUSY);
 681         }
 682         if (mddev->level == 4)
 683                 return raid0_takeover_raid45(mddev);
 684
 685         if (mddev->level == 5) {
 686                 if (mddev->layout == ALGORITHM_PARITY_N)
 687                         return raid0_takeover_raid45(mddev);
 688
 689                 printk(KERN_ERR "md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
 690                        mdname(mddev), ALGORITHM_PARITY_N);
 691         }
 692
 693         if (mddev->level == 10)
 694                 return raid0_takeover_raid10(mddev);
 695
 696         if (mddev->level == 1)
 697                 return raid0_takeover_raid1(mddev);
 698
 699         printk(KERN_ERR "Takeover from raid%i to raid0 not supported\n",
 700                 mddev->level);
 701
 702         return ERR_PTR(-EINVAL);
 703 }
 704
 705 static void raid0_quiesce(struct mddev *mddev, int state)
 706 {
 707 }
 708
 709 static struct md_personality raid0_personality=
 710 {
 711         .name           = "raid0",
 712         .level          = 0,
 713         .owner          = THIS_MODULE,
 714         .make_request   = raid0_make_request,
 715         .run            = raid0_run,
 716         .free           = raid0_free,
 717         .status         = raid0_status,
 718         .size           = raid0_size,
 719         .takeover       = raid0_takeover,
 720         .quiesce        = raid0_quiesce,
 721         .congested      = raid0_congested,
 722         .mergeable_bvec = raid0_mergeable_bvec,
 723 };
 724
 725 static int __init raid0_init (void)
 726 {
 727         return register_md_personality (&raid0_personality);
 728 }
 729
 730 static void raid0_exit (void)
 731 {
 732         unregister_md_personality (&raid0_personality);
 733 }
 734
 735 module_init(raid0_init);
 736 module_exit(raid0_exit);
 737 MODULE_LICENSE("GPL");
 738 MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
 739 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 740 MODULE_ALIAS("md-raid0");
 741 MODULE_ALIAS("md-level-0");