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
   9    RAID-0 management functions.
  10
  11    This program is free software; you can redistribute it and/or modify
  12    it under the terms of the GNU General Public License as published by
  13    the Free Software Foundation; either version 2, or (at your option)
  14    any later version.
  15
  16    You should have received a copy of the GNU General Public License
  17    (for example /usr/src/linux/COPYING); if not, write to the Free
  18    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include <linux/blkdev.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/slab.h>
  24 #include "md.h"
  25 #include "raid0.h"
  26 #include "raid5.h"
  27
  28 static int raid0_congested(void *data, int bits)
  29 {
  30         struct mddev *mddev = data;
  31         raid0_conf_t *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         if (mddev_congested(mddev, bits))
  37                 return 1;
  38
  39         for (i = 0; i < raid_disks && !ret ; i++) {
  40                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  41
  42                 ret |= bdi_congested(&q->backing_dev_info, bits);
  43         }
  44         return ret;
  45 }
  46
  47 /*
  48  * inform the user of the raid configuration
  49 */
  50 static void dump_zones(struct mddev *mddev)
  51 {
  52         int j, k;
  53         sector_t zone_size = 0;
  54         sector_t zone_start = 0;
  55         char b[BDEVNAME_SIZE];
  56         raid0_conf_t *conf = mddev->private;
  57         int raid_disks = conf->strip_zone[0].nb_dev;
  58         printk(KERN_INFO "md: RAID0 configuration for %s - %d zone%s\n",
  59                mdname(mddev),
  60                conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
  61         for (j = 0; j < conf->nr_strip_zones; j++) {
  62                 printk(KERN_INFO "md: zone%d=[", j);
  63                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
  64                         printk(KERN_CONT "%s%s", k?"/":"",
  65                         bdevname(conf->devlist[j*raid_disks
  66                                                 + k]->bdev, b));
  67                 printk(KERN_CONT "]\n");
  68
  69                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
  70                 printk(KERN_INFO "      zone-offset=%10lluKB, "
  71                                 "device-offset=%10lluKB, size=%10lluKB\n",
  72                         (unsigned long long)zone_start>>1,
  73                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
  74                         (unsigned long long)zone_size>>1);
  75                 zone_start = conf->strip_zone[j].zone_end;
  76         }
  77         printk(KERN_INFO "\n");
  78 }
  79
  80 static int create_strip_zones(struct mddev *mddev, raid0_conf_t **private_conf)
  81 {
  82         int i, c, err;
  83         sector_t curr_zone_end, sectors;
  84         struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
  85         struct strip_zone *zone;
  86         int cnt;
  87         char b[BDEVNAME_SIZE];
  88         char b2[BDEVNAME_SIZE];
  89         raid0_conf_t *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
  90
  91         if (!conf)
  92                 return -ENOMEM;
  93         list_for_each_entry(rdev1, &mddev->disks, same_set) {
  94                 pr_debug("md/raid0:%s: looking at %s\n",
  95                          mdname(mddev),
  96                          bdevname(rdev1->bdev, b));
  97                 c = 0;
  98
  99                 /* round size to chunk_size */
 100                 sectors = rdev1->sectors;
 101                 sector_div(sectors, mddev->chunk_sectors);
 102                 rdev1->sectors = sectors * mddev->chunk_sectors;
 103
 104                 list_for_each_entry(rdev2, &mddev->disks, same_set) {
 105                         pr_debug("md/raid0:%s:   comparing %s(%llu)"
 106                                  " with %s(%llu)\n",
 107                                  mdname(mddev),
 108                                  bdevname(rdev1->bdev,b),
 109                                  (unsigned long long)rdev1->sectors,
 110                                  bdevname(rdev2->bdev,b2),
 111                                  (unsigned long long)rdev2->sectors);
 112                         if (rdev2 == rdev1) {
 113                                 pr_debug("md/raid0:%s:   END\n",
 114                                          mdname(mddev));
 115                                 break;
 116                         }
 117                         if (rdev2->sectors == rdev1->sectors) {
 118                                 /*
 119                                  * Not unique, don't count it as a new
 120                                  * group
 121                                  */
 122                                 pr_debug("md/raid0:%s:   EQUAL\n",
 123                                          mdname(mddev));
 124                                 c = 1;
 125                                 break;
 126                         }
 127                         pr_debug("md/raid0:%s:   NOT EQUAL\n",
 128                                  mdname(mddev));
 129                 }
 130                 if (!c) {
 131                         pr_debug("md/raid0:%s:   ==> UNIQUE\n",
 132                                  mdname(mddev));
 133                         conf->nr_strip_zones++;
 134                         pr_debug("md/raid0:%s: %d zones\n",
 135                                  mdname(mddev), conf->nr_strip_zones);
 136                 }
 137         }
 138         pr_debug("md/raid0:%s: FINAL %d zones\n",
 139                  mdname(mddev), conf->nr_strip_zones);
 140         err = -ENOMEM;
 141         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 142                                 conf->nr_strip_zones, GFP_KERNEL);
 143         if (!conf->strip_zone)
 144                 goto abort;
 145         conf->devlist = kzalloc(sizeof(struct md_rdev*)*
 146                                 conf->nr_strip_zones*mddev->raid_disks,
 147                                 GFP_KERNEL);
 148         if (!conf->devlist)
 149                 goto abort;
 150
 151         /* The first zone must contain all devices, so here we check that
 152          * there is a proper alignment of slots to devices and find them all
 153          */
 154         zone = &conf->strip_zone[0];
 155         cnt = 0;
 156         smallest = NULL;
 157         dev = conf->devlist;
 158         err = -EINVAL;
 159         list_for_each_entry(rdev1, &mddev->disks, same_set) {
 160                 int j = rdev1->raid_disk;
 161
 162                 if (mddev->level == 10) {
 163                         /* taking over a raid10-n2 array */
 164                         j /= 2;
 165                         rdev1->new_raid_disk = j;
 166                 }
 167
 168                 if (mddev->level == 1) {
 169                         /* taiking over a raid1 array-
 170                          * we have only one active disk
 171                          */
 172                         j = 0;
 173                         rdev1->new_raid_disk = j;
 174                 }
 175
 176                 if (j < 0 || j >= mddev->raid_disks) {
 177                         printk(KERN_ERR "md/raid0:%s: bad disk number %d - "
 178                                "aborting!\n", mdname(mddev), j);
 179                         goto abort;
 180                 }
 181                 if (dev[j]) {
 182                         printk(KERN_ERR "md/raid0:%s: multiple devices for %d - "
 183                                "aborting!\n", mdname(mddev), j);
 184                         goto abort;
 185                 }
 186                 dev[j] = rdev1;
 187
 188                 disk_stack_limits(mddev->gendisk, rdev1->bdev,
 189                                   rdev1->data_offset << 9);
 190                 /* as we don't honour merge_bvec_fn, we must never risk
 191                  * violating it, so limit ->max_segments to 1, lying within
 192                  * a single page.
 193                  */
 194
 195                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn) {
 196                         blk_queue_max_segments(mddev->queue, 1);
 197                         blk_queue_segment_boundary(mddev->queue,
 198                                                    PAGE_CACHE_SIZE - 1);
 199                 }
 200                 if (!smallest || (rdev1->sectors < smallest->sectors))
 201                         smallest = rdev1;
 202                 cnt++;
 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         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
 263         mddev->queue->backing_dev_info.congested_data = mddev;
 264
 265         /*
 266          * now since we have the hard sector sizes, we can make sure
 267          * chunk size is a multiple of that sector size
 268          */
 269         if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
 270                 printk(KERN_ERR "md/raid0:%s: chunk_size of %d not valid\n",
 271                        mdname(mddev),
 272                        mddev->chunk_sectors << 9);
 273                 goto abort;
 274         }
 275
 276         blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 277         blk_queue_io_opt(mddev->queue,
 278                          (mddev->chunk_sectors << 9) * mddev->raid_disks);
 279
 280         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 281         *private_conf = conf;
 282
 283         return 0;
 284 abort:
 285         kfree(conf->strip_zone);
 286         kfree(conf->devlist);
 287         kfree(conf);
 288         *private_conf = NULL;
 289         return err;
 290 }
 291
 292 /**
 293  *      raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
 294  *      @q: request queue
 295  *      @bvm: properties of new bio
 296  *      @biovec: the request that could be merged to it.
 297  *
 298  *      Return amount of bytes we can accept at this offset
 299  */
 300 static int raid0_mergeable_bvec(struct request_queue *q,
 301                                 struct bvec_merge_data *bvm,
 302                                 struct bio_vec *biovec)
 303 {
 304         struct mddev *mddev = q->queuedata;
 305         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 306         int max;
 307         unsigned int chunk_sectors = mddev->chunk_sectors;
 308         unsigned int bio_sectors = bvm->bi_size >> 9;
 309
 310         if (is_power_of_2(chunk_sectors))
 311                 max =  (chunk_sectors - ((sector & (chunk_sectors-1))
 312                                                 + bio_sectors)) << 9;
 313         else
 314                 max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
 315                                                 + bio_sectors)) << 9;
 316         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
 317         if (max <= biovec->bv_len && bio_sectors == 0)
 318                 return biovec->bv_len;
 319         else
 320                 return max;
 321 }
 322
 323 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 324 {
 325         sector_t array_sectors = 0;
 326         struct md_rdev *rdev;
 327
 328         WARN_ONCE(sectors || raid_disks,
 329                   "%s does not support generic reshape\n", __func__);
 330
 331         list_for_each_entry(rdev, &mddev->disks, same_set)
 332                 array_sectors += rdev->sectors;
 333
 334         return array_sectors;
 335 }
 336
 337 static int raid0_run(struct mddev *mddev)
 338 {
 339         raid0_conf_t *conf;
 340         int ret;
 341
 342         if (mddev->chunk_sectors == 0) {
 343                 printk(KERN_ERR "md/raid0:%s: chunk size must be set.\n",
 344                        mdname(mddev));
 345                 return -EINVAL;
 346         }
 347         if (md_check_no_bitmap(mddev))
 348                 return -EINVAL;
 349         blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 350
 351         /* if private is not null, we are here after takeover */
 352         if (mddev->private == NULL) {
 353                 ret = create_strip_zones(mddev, &conf);
 354                 if (ret < 0)
 355                         return ret;
 356                 mddev->private = conf;
 357         }
 358         conf = mddev->private;
 359
 360         /* calculate array device size */
 361         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 362
 363         printk(KERN_INFO "md/raid0:%s: md_size is %llu sectors.\n",
 364                mdname(mddev),
 365                (unsigned long long)mddev->array_sectors);
 366         /* calculate the max read-ahead size.
 367          * For read-ahead of large files to be effective, we need to
 368          * readahead at least twice a whole stripe. i.e. number of devices
 369          * multiplied by chunk size times 2.
 370          * If an individual device has an ra_pages greater than the
 371          * chunk size, then we will not drive that device as hard as it
 372          * wants.  We consider this a configuration error: a larger
 373          * chunksize should be used in that case.
 374          */
 375         {
 376                 int stripe = mddev->raid_disks *
 377                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
 378                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 379                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 380         }
 381
 382         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 383         dump_zones(mddev);
 384         return md_integrity_register(mddev);
 385 }
 386
 387 static int raid0_stop(struct mddev *mddev)
 388 {
 389         raid0_conf_t *conf = mddev->private;
 390
 391         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 392         kfree(conf->strip_zone);
 393         kfree(conf->devlist);
 394         kfree(conf);
 395         mddev->private = NULL;
 396         return 0;
 397 }
 398
 399 /* Find the zone which holds a particular offset
 400  * Update *sectorp to be an offset in that zone
 401  */
 402 static struct strip_zone *find_zone(struct raid0_private_data *conf,
 403                                     sector_t *sectorp)
 404 {
 405         int i;
 406         struct strip_zone *z = conf->strip_zone;
 407         sector_t sector = *sectorp;
 408
 409         for (i = 0; i < conf->nr_strip_zones; i++)
 410                 if (sector < z[i].zone_end) {
 411                         if (i)
 412                                 *sectorp = sector - z[i-1].zone_end;
 413                         return z + i;
 414                 }
 415         BUG();
 416 }
 417
 418 /*
 419  * remaps the bio to the target device. we separate two flows.
 420  * power 2 flow and a general flow for the sake of perfromance
 421 */
 422 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 423                                 sector_t sector, sector_t *sector_offset)
 424 {
 425         unsigned int sect_in_chunk;
 426         sector_t chunk;
 427         raid0_conf_t *conf = mddev->private;
 428         int raid_disks = conf->strip_zone[0].nb_dev;
 429         unsigned int chunk_sects = mddev->chunk_sectors;
 430
 431         if (is_power_of_2(chunk_sects)) {
 432                 int chunksect_bits = ffz(~chunk_sects);
 433                 /* find the sector offset inside the chunk */
 434                 sect_in_chunk  = sector & (chunk_sects - 1);
 435                 sector >>= chunksect_bits;
 436                 /* chunk in zone */
 437                 chunk = *sector_offset;
 438                 /* quotient is the chunk in real device*/
 439                 sector_div(chunk, zone->nb_dev << chunksect_bits);
 440         } else{
 441                 sect_in_chunk = sector_div(sector, chunk_sects);
 442                 chunk = *sector_offset;
 443                 sector_div(chunk, chunk_sects * zone->nb_dev);
 444         }
 445         /*
 446         *  position the bio over the real device
 447         *  real sector = chunk in device + starting of zone
 448         *       + the position in the chunk
 449         */
 450         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
 451         return conf->devlist[(zone - conf->strip_zone)*raid_disks
 452                              + sector_div(sector, zone->nb_dev)];
 453 }
 454
 455 /*
 456  * Is io distribute over 1 or more chunks ?
 457 */
 458 static inline int is_io_in_chunk_boundary(struct mddev *mddev,
 459                         unsigned int chunk_sects, struct bio *bio)
 460 {
 461         if (likely(is_power_of_2(chunk_sects))) {
 462                 return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
 463                                         + (bio->bi_size >> 9));
 464         } else{
 465                 sector_t sector = bio->bi_sector;
 466                 return chunk_sects >= (sector_div(sector, chunk_sects)
 467                                                 + (bio->bi_size >> 9));
 468         }
 469 }
 470
 471 static int raid0_make_request(struct mddev *mddev, struct bio *bio)
 472 {
 473         unsigned int chunk_sects;
 474         sector_t sector_offset;
 475         struct strip_zone *zone;
 476         struct md_rdev *tmp_dev;
 477
 478         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 479                 md_flush_request(mddev, bio);
 480                 return 0;
 481         }
 482
 483         chunk_sects = mddev->chunk_sectors;
 484         if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
 485                 sector_t sector = bio->bi_sector;
 486                 struct bio_pair *bp;
 487                 /* Sanity check -- queue functions should prevent this happening */
 488                 if (bio->bi_vcnt != 1 ||
 489                     bio->bi_idx != 0)
 490                         goto bad_map;
 491                 /* This is a one page bio that upper layers
 492                  * refuse to split for us, so we need to split it.
 493                  */
 494                 if (likely(is_power_of_2(chunk_sects)))
 495                         bp = bio_split(bio, chunk_sects - (sector &
 496                                                            (chunk_sects-1)));
 497                 else
 498                         bp = bio_split(bio, chunk_sects -
 499                                        sector_div(sector, chunk_sects));
 500                 if (raid0_make_request(mddev, &bp->bio1))
 501                         generic_make_request(&bp->bio1);
 502                 if (raid0_make_request(mddev, &bp->bio2))
 503                         generic_make_request(&bp->bio2);
 504
 505                 bio_pair_release(bp);
 506                 return 0;
 507         }
 508
 509         sector_offset = bio->bi_sector;
 510         zone =  find_zone(mddev->private, &sector_offset);
 511         tmp_dev = map_sector(mddev, zone, bio->bi_sector,
 512                              &sector_offset);
 513         bio->bi_bdev = tmp_dev->bdev;
 514         bio->bi_sector = sector_offset + zone->dev_start +
 515                 tmp_dev->data_offset;
 516         /*
 517          * Let the main block layer submit the IO and resolve recursion:
 518          */
 519         return 1;
 520
 521 bad_map:
 522         printk("md/raid0:%s: make_request bug: can't convert block across chunks"
 523                " or bigger than %dk %llu %d\n",
 524                mdname(mddev), chunk_sects / 2,
 525                (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 526
 527         bio_io_error(bio);
 528         return 0;
 529 }
 530
 531 static void raid0_status(struct seq_file *seq, struct mddev *mddev)
 532 {
 533         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 534         return;
 535 }
 536
 537 static void *raid0_takeover_raid45(struct mddev *mddev)
 538 {
 539         struct md_rdev *rdev;
 540         raid0_conf_t *priv_conf;
 541
 542         if (mddev->degraded != 1) {
 543                 printk(KERN_ERR "md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
 544                        mdname(mddev),
 545                        mddev->degraded);
 546                 return ERR_PTR(-EINVAL);
 547         }
 548
 549         list_for_each_entry(rdev, &mddev->disks, same_set) {
 550                 /* check slot number for a disk */
 551                 if (rdev->raid_disk == mddev->raid_disks-1) {
 552                         printk(KERN_ERR "md/raid0:%s: raid5 must have missing parity disk!\n",
 553                                mdname(mddev));
 554                         return ERR_PTR(-EINVAL);
 555                 }
 556         }
 557
 558         /* Set new parameters */
 559         mddev->new_level = 0;
 560         mddev->new_layout = 0;
 561         mddev->new_chunk_sectors = mddev->chunk_sectors;
 562         mddev->raid_disks--;
 563         mddev->delta_disks = -1;
 564         /* make sure it will be not marked as dirty */
 565         mddev->recovery_cp = MaxSector;
 566
 567         create_strip_zones(mddev, &priv_conf);
 568         return priv_conf;
 569 }
 570
 571 static void *raid0_takeover_raid10(struct mddev *mddev)
 572 {
 573         raid0_conf_t *priv_conf;
 574
 575         /* Check layout:
 576          *  - far_copies must be 1
 577          *  - near_copies must be 2
 578          *  - disks number must be even
 579          *  - all mirrors must be already degraded
 580          */
 581         if (mddev->layout != ((1 << 8) + 2)) {
 582                 printk(KERN_ERR "md/raid0:%s:: Raid0 cannot takover layout: 0x%x\n",
 583                        mdname(mddev),
 584                        mddev->layout);
 585                 return ERR_PTR(-EINVAL);
 586         }
 587         if (mddev->raid_disks & 1) {
 588                 printk(KERN_ERR "md/raid0:%s: Raid0 cannot takover Raid10 with odd disk number.\n",
 589                        mdname(mddev));
 590                 return ERR_PTR(-EINVAL);
 591         }
 592         if (mddev->degraded != (mddev->raid_disks>>1)) {
 593                 printk(KERN_ERR "md/raid0:%s: All mirrors must be already degraded!\n",
 594                        mdname(mddev));
 595                 return ERR_PTR(-EINVAL);
 596         }
 597
 598         /* Set new parameters */
 599         mddev->new_level = 0;
 600         mddev->new_layout = 0;
 601         mddev->new_chunk_sectors = mddev->chunk_sectors;
 602         mddev->delta_disks = - mddev->raid_disks / 2;
 603         mddev->raid_disks += mddev->delta_disks;
 604         mddev->degraded = 0;
 605         /* make sure it will be not marked as dirty */
 606         mddev->recovery_cp = MaxSector;
 607
 608         create_strip_zones(mddev, &priv_conf);
 609         return priv_conf;
 610 }
 611
 612 static void *raid0_takeover_raid1(struct mddev *mddev)
 613 {
 614         raid0_conf_t *priv_conf;
 615
 616         /* Check layout:
 617          *  - (N - 1) mirror drives must be already faulty
 618          */
 619         if ((mddev->raid_disks - 1) != mddev->degraded) {
 620                 printk(KERN_ERR "md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
 621                        mdname(mddev));
 622                 return ERR_PTR(-EINVAL);
 623         }
 624
 625         /* Set new parameters */
 626         mddev->new_level = 0;
 627         mddev->new_layout = 0;
 628         mddev->new_chunk_sectors = 128; /* by default set chunk size to 64k */
 629         mddev->delta_disks = 1 - mddev->raid_disks;
 630         mddev->raid_disks = 1;
 631         /* make sure it will be not marked as dirty */
 632         mddev->recovery_cp = MaxSector;
 633
 634         create_strip_zones(mddev, &priv_conf);
 635         return priv_conf;
 636 }
 637
 638 static void *raid0_takeover(struct mddev *mddev)
 639 {
 640         /* raid0 can take over:
 641          *  raid4 - if all data disks are active.
 642          *  raid5 - providing it is Raid4 layout and one disk is faulty
 643          *  raid10 - assuming we have all necessary active disks
 644          *  raid1 - with (N -1) mirror drives faulty
 645          */
 646         if (mddev->level == 4)
 647                 return raid0_takeover_raid45(mddev);
 648
 649         if (mddev->level == 5) {
 650                 if (mddev->layout == ALGORITHM_PARITY_N)
 651                         return raid0_takeover_raid45(mddev);
 652
 653                 printk(KERN_ERR "md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
 654                        mdname(mddev), ALGORITHM_PARITY_N);
 655         }
 656
 657         if (mddev->level == 10)
 658                 return raid0_takeover_raid10(mddev);
 659
 660         if (mddev->level == 1)
 661                 return raid0_takeover_raid1(mddev);
 662
 663         printk(KERN_ERR "Takeover from raid%i to raid0 not supported\n",
 664                 mddev->level);
 665
 666         return ERR_PTR(-EINVAL);
 667 }
 668
 669 static void raid0_quiesce(struct mddev *mddev, int state)
 670 {
 671 }
 672
 673 static struct mdk_personality raid0_personality=
 674 {
 675         .name           = "raid0",
 676         .level          = 0,
 677         .owner          = THIS_MODULE,
 678         .make_request   = raid0_make_request,
 679         .run            = raid0_run,
 680         .stop           = raid0_stop,
 681         .status         = raid0_status,
 682         .size           = raid0_size,
 683         .takeover       = raid0_takeover,
 684         .quiesce        = raid0_quiesce,
 685 };
 686
 687 static int __init raid0_init (void)
 688 {
 689         return register_md_personality (&raid0_personality);
 690 }
 691
 692 static void raid0_exit (void)
 693 {
 694         unregister_md_personality (&raid0_personality);
 695 }
 696
 697 module_init(raid0_init);
 698 module_exit(raid0_exit);
 699 MODULE_LICENSE("GPL");
 700 MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
 701 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 702 MODULE_ALIAS("md-raid0");
 703 MODULE_ALIAS("md-level-0");