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/module.h>
  24 #include <linux/slab.h>
  25 #include "md.h"
  26 #include "raid0.h"
  27 #include "raid5.h"
  28
  29 static int raid0_congested(void *data, int bits)
  30 {
  31         struct mddev *mddev = data;
  32         struct r0conf *conf = mddev->private;
  33         struct md_rdev **devlist = conf->devlist;
  34         int raid_disks = conf->strip_zone[0].nb_dev;
  35         int i, ret = 0;
  36
  37         if (mddev_congested(mddev, bits))
  38                 return 1;
  39
  40         for (i = 0; i < raid_disks && !ret ; i++) {
  41                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  42
  43                 ret |= bdi_congested(&q->backing_dev_info, bits);
  44         }
  45         return ret;
  46 }
  47
  48 /*
  49  * inform the user of the raid configuration
  50 */
  51 static void dump_zones(struct mddev *mddev)
  52 {
  53         int j, k;
  54         sector_t zone_size = 0;
  55         sector_t zone_start = 0;
  56         char b[BDEVNAME_SIZE];
  57         struct r0conf *conf = mddev->private;
  58         int raid_disks = conf->strip_zone[0].nb_dev;
  59         printk(KERN_INFO "md: RAID0 configuration for %s - %d zone%s\n",
  60                mdname(mddev),
  61                conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
  62         for (j = 0; j < conf->nr_strip_zones; j++) {
  63                 printk(KERN_INFO "md: zone%d=[", j);
  64                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
  65                         printk(KERN_CONT "%s%s", k?"/":"",
  66                         bdevname(conf->devlist[j*raid_disks
  67                                                 + k]->bdev, b));
  68                 printk(KERN_CONT "]\n");
  69
  70                 zone_size  = conf->strip_zone[j].zone_end - zone_start;
  71                 printk(KERN_INFO "      zone-offset=%10lluKB, "
  72                                 "device-offset=%10lluKB, size=%10lluKB\n",
  73                         (unsigned long long)zone_start>>1,
  74                         (unsigned long long)conf->strip_zone[j].dev_start>>1,
  75                         (unsigned long long)zone_size>>1);
  76                 zone_start = conf->strip_zone[j].zone_end;
  77         }
  78         printk(KERN_INFO "\n");
  79 }
  80
  81 static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
  82 {
  83         int i, c, err;
  84         sector_t curr_zone_end, sectors;
  85         struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
  86         struct strip_zone *zone;
  87         int cnt;
  88         char b[BDEVNAME_SIZE];
  89         char b2[BDEVNAME_SIZE];
  90         struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
  91         bool discard_supported = false;
  92
  93         if (!conf)
  94                 return -ENOMEM;
  95         rdev_for_each(rdev1, mddev) {
  96                 pr_debug("md/raid0:%s: looking at %s\n",
  97                          mdname(mddev),
  98                          bdevname(rdev1->bdev, b));
  99                 c = 0;
 100
 101                 /* round size to chunk_size */
 102                 sectors = rdev1->sectors;
 103                 sector_div(sectors, mddev->chunk_sectors);
 104                 rdev1->sectors = sectors * mddev->chunk_sectors;
 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         err = -ENOMEM;
 143         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 144                                 conf->nr_strip_zones, GFP_KERNEL);
 145         if (!conf->strip_zone)
 146                 goto abort;
 147         conf->devlist = kzalloc(sizeof(struct md_rdev*)*
 148                                 conf->nr_strip_zones*mddev->raid_disks,
 149                                 GFP_KERNEL);
 150         if (!conf->devlist)
 151                 goto abort;
 152
 153         /* The first zone must contain all devices, so here we check that
 154          * there is a proper alignment of slots to devices and find them all
 155          */
 156         zone = &conf->strip_zone[0];
 157         cnt = 0;
 158         smallest = NULL;
 159         dev = conf->devlist;
 160         err = -EINVAL;
 161         rdev_for_each(rdev1, mddev) {
 162                 int j = rdev1->raid_disk;
 163
 164                 if (mddev->level == 10) {
 165                         /* taking over a raid10-n2 array */
 166                         j /= 2;
 167                         rdev1->new_raid_disk = j;
 168                 }
 169
 170                 if (mddev->level == 1) {
 171                         /* taiking over a raid1 array-
 172                          * we have only one active disk
 173                          */
 174                         j = 0;
 175                         rdev1->new_raid_disk = j;
 176                 }
 177
 178                 if (j < 0) {
 179                         printk(KERN_ERR
 180                                "md/raid0:%s: remove inactive devices before converting to RAID0\n",
 181                                mdname(mddev));
 182                         goto abort;
 183                 }
 184                 if (j >= mddev->raid_disks) {
 185                         printk(KERN_ERR "md/raid0:%s: bad disk number %d - "
 186                                "aborting!\n", mdname(mddev), j);
 187                         goto abort;
 188                 }
 189                 if (dev[j]) {
 190                         printk(KERN_ERR "md/raid0:%s: multiple devices for %d - "
 191                                "aborting!\n", mdname(mddev), j);
 192                         goto abort;
 193                 }
 194                 dev[j] = rdev1;
 195
 196                 disk_stack_limits(mddev->gendisk, rdev1->bdev,
 197                                   rdev1->data_offset << 9);
 198
 199                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
 200                         conf->has_merge_bvec = 1;
 201
 202                 if (!smallest || (rdev1->sectors < smallest->sectors))
 203                         smallest = rdev1;
 204                 cnt++;
 205
 206                 if (blk_queue_discard(bdev_get_queue(rdev1->bdev)))
 207                         discard_supported = true;
 208         }
 209         if (cnt != mddev->raid_disks) {
 210                 printk(KERN_ERR "md/raid0:%s: too few disks (%d of %d) - "
 211                        "aborting!\n", mdname(mddev), cnt, mddev->raid_disks);
 212                 goto abort;
 213         }
 214         zone->nb_dev = cnt;
 215         zone->zone_end = smallest->sectors * cnt;
 216
 217         curr_zone_end = zone->zone_end;
 218
 219         /* now do the other zones */
 220         for (i = 1; i < conf->nr_strip_zones; i++)
 221         {
 222                 int j;
 223
 224                 zone = conf->strip_zone + i;
 225                 dev = conf->devlist + i * mddev->raid_disks;
 226
 227                 pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
 228                 zone->dev_start = smallest->sectors;
 229                 smallest = NULL;
 230                 c = 0;
 231
 232                 for (j=0; j<cnt; j++) {
 233                         rdev = conf->devlist[j];
 234                         if (rdev->sectors <= zone->dev_start) {
 235                                 pr_debug("md/raid0:%s: checking %s ... nope\n",
 236                                          mdname(mddev),
 237                                          bdevname(rdev->bdev, b));
 238                                 continue;
 239                         }
 240                         pr_debug("md/raid0:%s: checking %s ..."
 241                                  " contained as device %d\n",
 242                                  mdname(mddev),
 243                                  bdevname(rdev->bdev, b), c);
 244                         dev[c] = rdev;
 245                         c++;
 246                         if (!smallest || rdev->sectors < smallest->sectors) {
 247                                 smallest = rdev;
 248                                 pr_debug("md/raid0:%s:  (%llu) is smallest!.\n",
 249                                          mdname(mddev),
 250                                          (unsigned long long)rdev->sectors);
 251                         }
 252                 }
 253
 254                 zone->nb_dev = c;
 255                 sectors = (smallest->sectors - zone->dev_start) * c;
 256                 pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
 257                          mdname(mddev),
 258                          zone->nb_dev, (unsigned long long)sectors);
 259
 260                 curr_zone_end += sectors;
 261                 zone->zone_end = curr_zone_end;
 262
 263                 pr_debug("md/raid0:%s: current zone start: %llu\n",
 264                          mdname(mddev),
 265                          (unsigned long long)smallest->sectors);
 266         }
 267         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
 268         mddev->queue->backing_dev_info.congested_data = mddev;
 269
 270         /*
 271          * now since we have the hard sector sizes, we can make sure
 272          * chunk size is a multiple of that sector size
 273          */
 274         if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
 275                 printk(KERN_ERR "md/raid0:%s: chunk_size of %d not valid\n",
 276                        mdname(mddev),
 277                        mddev->chunk_sectors << 9);
 278                 goto abort;
 279         }
 280
 281         blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 282         blk_queue_io_opt(mddev->queue,
 283                          (mddev->chunk_sectors << 9) * mddev->raid_disks);
 284
 285         if (!discard_supported)
 286                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 287         else
 288                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 289
 290         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 291         *private_conf = conf;
 292
 293         return 0;
 294 abort:
 295         kfree(conf->strip_zone);
 296         kfree(conf->devlist);
 297         kfree(conf);
 298         *private_conf = ERR_PTR(err);
 299         return err;
 300 }
 301
 302 /* Find the zone which holds a particular offset
 303  * Update *sectorp to be an offset in that zone
 304  */
 305 static struct strip_zone *find_zone(struct r0conf *conf,
 306                                     sector_t *sectorp)
 307 {
 308         int i;
 309         struct strip_zone *z = conf->strip_zone;
 310         sector_t sector = *sectorp;
 311
 312         for (i = 0; i < conf->nr_strip_zones; i++)
 313                 if (sector < z[i].zone_end) {
 314                         if (i)
 315                                 *sectorp = sector - z[i-1].zone_end;
 316                         return z + i;
 317                 }
 318         BUG();
 319 }
 320
 321 /*
 322  * remaps the bio to the target device. we separate two flows.
 323  * power 2 flow and a general flow for the sake of perfromance
 324 */
 325 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 326                                 sector_t sector, sector_t *sector_offset)
 327 {
 328         unsigned int sect_in_chunk;
 329         sector_t chunk;
 330         struct r0conf *conf = mddev->private;
 331         int raid_disks = conf->strip_zone[0].nb_dev;
 332         unsigned int chunk_sects = mddev->chunk_sectors;
 333
 334         if (is_power_of_2(chunk_sects)) {
 335                 int chunksect_bits = ffz(~chunk_sects);
 336                 /* find the sector offset inside the chunk */
 337                 sect_in_chunk  = sector & (chunk_sects - 1);
 338                 sector >>= chunksect_bits;
 339                 /* chunk in zone */
 340                 chunk = *sector_offset;
 341                 /* quotient is the chunk in real device*/
 342                 sector_div(chunk, zone->nb_dev << chunksect_bits);
 343         } else{
 344                 sect_in_chunk = sector_div(sector, chunk_sects);
 345                 chunk = *sector_offset;
 346                 sector_div(chunk, chunk_sects * zone->nb_dev);
 347         }
 348         /*
 349         *  position the bio over the real device
 350         *  real sector = chunk in device + starting of zone
 351         *       + the position in the chunk
 352         */
 353         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
 354         return conf->devlist[(zone - conf->strip_zone)*raid_disks
 355                              + sector_div(sector, zone->nb_dev)];
 356 }
 357
 358 /**
 359  *      raid0_mergeable_bvec -- tell bio layer if two requests can be merged
 360  *      @q: request queue
 361  *      @bvm: properties of new bio
 362  *      @biovec: the request that could be merged to it.
 363  *
 364  *      Return amount of bytes we can accept at this offset
 365  */
 366 static int raid0_mergeable_bvec(struct request_queue *q,
 367                                 struct bvec_merge_data *bvm,
 368                                 struct bio_vec *biovec)
 369 {
 370         struct mddev *mddev = q->queuedata;
 371         struct r0conf *conf = mddev->private;
 372         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 373         sector_t sector_offset = sector;
 374         int max;
 375         unsigned int chunk_sectors = mddev->chunk_sectors;
 376         unsigned int bio_sectors = bvm->bi_size >> 9;
 377         struct strip_zone *zone;
 378         struct md_rdev *rdev;
 379         struct request_queue *subq;
 380
 381         if (is_power_of_2(chunk_sectors))
 382                 max =  (chunk_sectors - ((sector & (chunk_sectors-1))
 383                                                 + bio_sectors)) << 9;
 384         else
 385                 max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
 386                                                 + bio_sectors)) << 9;
 387         if (max < 0)
 388                 max = 0; /* bio_add cannot handle a negative return */
 389         if (max <= biovec->bv_len && bio_sectors == 0)
 390                 return biovec->bv_len;
 391         if (max < biovec->bv_len)
 392                 /* too small already, no need to check further */
 393                 return max;
 394         if (!conf->has_merge_bvec)
 395                 return max;
 396
 397         /* May need to check subordinate device */
 398         sector = sector_offset;
 399         zone = find_zone(mddev->private, &sector_offset);
 400         rdev = map_sector(mddev, zone, sector, &sector_offset);
 401         subq = bdev_get_queue(rdev->bdev);
 402         if (subq->merge_bvec_fn) {
 403                 bvm->bi_bdev = rdev->bdev;
 404                 bvm->bi_sector = sector_offset + zone->dev_start +
 405                         rdev->data_offset;
 406                 return min(max, subq->merge_bvec_fn(subq, bvm, biovec));
 407         } else
 408                 return max;
 409 }
 410
 411 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 412 {
 413         sector_t array_sectors = 0;
 414         struct md_rdev *rdev;
 415
 416         WARN_ONCE(sectors || raid_disks,
 417                   "%s does not support generic reshape\n", __func__);
 418
 419         rdev_for_each(rdev, mddev)
 420                 array_sectors += (rdev->sectors &
 421                                   ~(sector_t)(mddev->chunk_sectors-1));
 422
 423         return array_sectors;
 424 }
 425
 426 static int raid0_stop(struct mddev *mddev);
 427
 428 static int raid0_run(struct mddev *mddev)
 429 {
 430         struct r0conf *conf;
 431         int ret;
 432
 433         if (mddev->chunk_sectors == 0) {
 434                 printk(KERN_ERR "md/raid0:%s: chunk size must be set.\n",
 435                        mdname(mddev));
 436                 return -EINVAL;
 437         }
 438         if (md_check_no_bitmap(mddev))
 439                 return -EINVAL;
 440         blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 441         blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 442         blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
 443
 444         /* if private is not null, we are here after takeover */
 445         if (mddev->private == NULL) {
 446                 ret = create_strip_zones(mddev, &conf);
 447                 if (ret < 0)
 448                         return ret;
 449                 mddev->private = conf;
 450         }
 451         conf = mddev->private;
 452
 453         /* calculate array device size */
 454         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 455
 456         printk(KERN_INFO "md/raid0:%s: md_size is %llu sectors.\n",
 457                mdname(mddev),
 458                (unsigned long long)mddev->array_sectors);
 459         /* calculate the max read-ahead size.
 460          * For read-ahead of large files to be effective, we need to
 461          * readahead at least twice a whole stripe. i.e. number of devices
 462          * multiplied by chunk size times 2.
 463          * If an individual device has an ra_pages greater than the
 464          * chunk size, then we will not drive that device as hard as it
 465          * wants.  We consider this a configuration error: a larger
 466          * chunksize should be used in that case.
 467          */
 468         {
 469                 int stripe = mddev->raid_disks *
 470                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
 471                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 472                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 473         }
 474
 475         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 476         dump_zones(mddev);
 477
 478         ret = md_integrity_register(mddev);
 479         if (ret)
 480                 raid0_stop(mddev);
 481
 482         return ret;
 483 }
 484
 485 static int raid0_stop(struct mddev *mddev)
 486 {
 487         struct r0conf *conf = mddev->private;
 488
 489         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 490         kfree(conf->strip_zone);
 491         kfree(conf->devlist);
 492         kfree(conf);
 493         mddev->private = NULL;
 494         return 0;
 495 }
 496
 497 /*
 498  * Is io distribute over 1 or more chunks ?
 499 */
 500 static inline int is_io_in_chunk_boundary(struct mddev *mddev,
 501                         unsigned int chunk_sects, struct bio *bio)
 502 {
 503         if (likely(is_power_of_2(chunk_sects))) {
 504                 return chunk_sects >=
 505                         ((bio->bi_iter.bi_sector & (chunk_sects-1))
 506                                         + bio_sectors(bio));
 507         } else{
 508                 sector_t sector = bio->bi_iter.bi_sector;
 509                 return chunk_sects >= (sector_div(sector, chunk_sects)
 510                                                 + bio_sectors(bio));
 511         }
 512 }
 513
 514 static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 515 {
 516         struct strip_zone *zone;
 517         struct md_rdev *tmp_dev;
 518         struct bio *split;
 519
 520         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 521                 md_flush_request(mddev, bio);
 522                 return;
 523         }
 524
 525         do {
 526                 sector_t sector = bio->bi_iter.bi_sector;
 527                 unsigned chunk_sects = mddev->chunk_sectors;
 528
 529                 unsigned sectors = chunk_sects -
 530                         (likely(is_power_of_2(chunk_sects))
 531                          ? (sector & (chunk_sects-1))
 532                          : sector_div(sector, chunk_sects));
 533
 534                 if (sectors < bio_sectors(bio)) {
 535                         split = bio_split(bio, sectors, GFP_NOIO, fs_bio_set);
 536                         bio_chain(split, bio);
 537                 } else {
 538                         split = bio;
 539                 }
 540
 541                 zone = find_zone(mddev->private, &sector);
 542                 tmp_dev = map_sector(mddev, zone, sector, &sector);
 543                 split->bi_bdev = tmp_dev->bdev;
 544                 split->bi_iter.bi_sector = sector + zone->dev_start +
 545                         tmp_dev->data_offset;
 546
 547                 if (unlikely((split->bi_rw & REQ_DISCARD) &&
 548                          !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
 549                         /* Just ignore it */
 550                         bio_endio(split, 0);
 551                 } else
 552                         generic_make_request(split);
 553         } while (split != bio);
 554 }
 555
 556 static void raid0_status(struct seq_file *seq, struct mddev *mddev)
 557 {
 558         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 559         return;
 560 }
 561
 562 static void *raid0_takeover_raid45(struct mddev *mddev)
 563 {
 564         struct md_rdev *rdev;
 565         struct r0conf *priv_conf;
 566
 567         if (mddev->degraded != 1) {
 568                 printk(KERN_ERR "md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
 569                        mdname(mddev),
 570                        mddev->degraded);
 571                 return ERR_PTR(-EINVAL);
 572         }
 573
 574         rdev_for_each(rdev, mddev) {
 575                 /* check slot number for a disk */
 576                 if (rdev->raid_disk == mddev->raid_disks-1) {
 577                         printk(KERN_ERR "md/raid0:%s: raid5 must have missing parity disk!\n",
 578                                mdname(mddev));
 579                         return ERR_PTR(-EINVAL);
 580                 }
 581                 rdev->sectors = mddev->dev_sectors;
 582         }
 583
 584         /* Set new parameters */
 585         mddev->new_level = 0;
 586         mddev->new_layout = 0;
 587         mddev->new_chunk_sectors = mddev->chunk_sectors;
 588         mddev->raid_disks--;
 589         mddev->delta_disks = -1;
 590         /* make sure it will be not marked as dirty */
 591         mddev->recovery_cp = MaxSector;
 592
 593         create_strip_zones(mddev, &priv_conf);
 594         return priv_conf;
 595 }
 596
 597 static void *raid0_takeover_raid10(struct mddev *mddev)
 598 {
 599         struct r0conf *priv_conf;
 600
 601         /* Check layout:
 602          *  - far_copies must be 1
 603          *  - near_copies must be 2
 604          *  - disks number must be even
 605          *  - all mirrors must be already degraded
 606          */
 607         if (mddev->layout != ((1 << 8) + 2)) {
 608                 printk(KERN_ERR "md/raid0:%s:: Raid0 cannot takover layout: 0x%x\n",
 609                        mdname(mddev),
 610                        mddev->layout);
 611                 return ERR_PTR(-EINVAL);
 612         }
 613         if (mddev->raid_disks & 1) {
 614                 printk(KERN_ERR "md/raid0:%s: Raid0 cannot takover Raid10 with odd disk number.\n",
 615                        mdname(mddev));
 616                 return ERR_PTR(-EINVAL);
 617         }
 618         if (mddev->degraded != (mddev->raid_disks>>1)) {
 619                 printk(KERN_ERR "md/raid0:%s: All mirrors must be already degraded!\n",
 620                        mdname(mddev));
 621                 return ERR_PTR(-EINVAL);
 622         }
 623
 624         /* Set new parameters */
 625         mddev->new_level = 0;
 626         mddev->new_layout = 0;
 627         mddev->new_chunk_sectors = mddev->chunk_sectors;
 628         mddev->delta_disks = - mddev->raid_disks / 2;
 629         mddev->raid_disks += mddev->delta_disks;
 630         mddev->degraded = 0;
 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_raid1(struct mddev *mddev)
 639 {
 640         struct r0conf *priv_conf;
 641         int chunksect;
 642
 643         /* Check layout:
 644          *  - (N - 1) mirror drives must be already faulty
 645          */
 646         if ((mddev->raid_disks - 1) != mddev->degraded) {
 647                 printk(KERN_ERR "md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
 648                        mdname(mddev));
 649                 return ERR_PTR(-EINVAL);
 650         }
 651
 652         /*
 653          * a raid1 doesn't have the notion of chunk size, so
 654          * figure out the largest suitable size we can use.
 655          */
 656         chunksect = 64 * 2; /* 64K by default */
 657
 658         /* The array must be an exact multiple of chunksize */
 659         while (chunksect && (mddev->array_sectors & (chunksect - 1)))
 660                 chunksect >>= 1;
 661
 662         if ((chunksect << 9) < PAGE_SIZE)
 663                 /* array size does not allow a suitable chunk size */
 664                 return ERR_PTR(-EINVAL);
 665
 666         /* Set new parameters */
 667         mddev->new_level = 0;
 668         mddev->new_layout = 0;
 669         mddev->new_chunk_sectors = chunksect;
 670         mddev->chunk_sectors = chunksect;
 671         mddev->delta_disks = 1 - mddev->raid_disks;
 672         mddev->raid_disks = 1;
 673         /* make sure it will be not marked as dirty */
 674         mddev->recovery_cp = MaxSector;
 675
 676         create_strip_zones(mddev, &priv_conf);
 677         return priv_conf;
 678 }
 679
 680 static void *raid0_takeover(struct mddev *mddev)
 681 {
 682         /* raid0 can take over:
 683          *  raid4 - if all data disks are active.
 684          *  raid5 - providing it is Raid4 layout and one disk is faulty
 685          *  raid10 - assuming we have all necessary active disks
 686          *  raid1 - with (N -1) mirror drives faulty
 687          */
 688         if (mddev->level == 4)
 689                 return raid0_takeover_raid45(mddev);
 690
 691         if (mddev->level == 5) {
 692                 if (mddev->layout == ALGORITHM_PARITY_N)
 693                         return raid0_takeover_raid45(mddev);
 694
 695                 printk(KERN_ERR "md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
 696                        mdname(mddev), ALGORITHM_PARITY_N);
 697         }
 698
 699         if (mddev->level == 10)
 700                 return raid0_takeover_raid10(mddev);
 701
 702         if (mddev->level == 1)
 703                 return raid0_takeover_raid1(mddev);
 704
 705         printk(KERN_ERR "Takeover from raid%i to raid0 not supported\n",
 706                 mddev->level);
 707
 708         return ERR_PTR(-EINVAL);
 709 }
 710
 711 static void raid0_quiesce(struct mddev *mddev, int state)
 712 {
 713 }
 714
 715 static struct md_personality raid0_personality=
 716 {
 717         .name           = "raid0",
 718         .level          = 0,
 719         .owner          = THIS_MODULE,
 720         .make_request   = raid0_make_request,
 721         .run            = raid0_run,
 722         .stop           = raid0_stop,
 723         .status         = raid0_status,
 724         .size           = raid0_size,
 725         .takeover       = raid0_takeover,
 726         .quiesce        = raid0_quiesce,
 727 };
 728
 729 static int __init raid0_init (void)
 730 {
 731         return register_md_personality (&raid0_personality);
 732 }
 733
 734 static void raid0_exit (void)
 735 {
 736         unregister_md_personality (&raid0_personality);
 737 }
 738
 739 module_init(raid0_init);
 740 module_exit(raid0_exit);
 741 MODULE_LICENSE("GPL");
 742 MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
 743 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 744 MODULE_ALIAS("md-raid0");
 745 MODULE_ALIAS("md-level-0");