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
  92         if (!conf)
  93                 return -ENOMEM;
  94         rdev_for_each(rdev1, mddev) {
  95                 pr_debug("md/raid0:%s: looking at %s\n",
  96                          mdname(mddev),
  97                          bdevname(rdev1->bdev, b));
  98                 c = 0;
  99
 100                 /* round size to chunk_size */
 101                 sectors = rdev1->sectors;
 102                 sector_div(sectors, mddev->chunk_sectors);
 103                 rdev1->sectors = sectors * mddev->chunk_sectors;
 104
 105                 rdev_for_each(rdev2, mddev) {
 106                         pr_debug("md/raid0:%s:   comparing %s(%llu)"
 107                                  " with %s(%llu)\n",
 108                                  mdname(mddev),
 109                                  bdevname(rdev1->bdev,b),
 110                                  (unsigned long long)rdev1->sectors,
 111                                  bdevname(rdev2->bdev,b2),
 112                                  (unsigned long long)rdev2->sectors);
 113                         if (rdev2 == rdev1) {
 114                                 pr_debug("md/raid0:%s:   END\n",
 115                                          mdname(mddev));
 116                                 break;
 117                         }
 118                         if (rdev2->sectors == rdev1->sectors) {
 119                                 /*
 120                                  * Not unique, don't count it as a new
 121                                  * group
 122                                  */
 123                                 pr_debug("md/raid0:%s:   EQUAL\n",
 124                                          mdname(mddev));
 125                                 c = 1;
 126                                 break;
 127                         }
 128                         pr_debug("md/raid0:%s:   NOT EQUAL\n",
 129                                  mdname(mddev));
 130                 }
 131                 if (!c) {
 132                         pr_debug("md/raid0:%s:   ==> UNIQUE\n",
 133                                  mdname(mddev));
 134                         conf->nr_strip_zones++;
 135                         pr_debug("md/raid0:%s: %d zones\n",
 136                                  mdname(mddev), conf->nr_strip_zones);
 137                 }
 138         }
 139         pr_debug("md/raid0:%s: FINAL %d zones\n",
 140                  mdname(mddev), conf->nr_strip_zones);
 141         err = -ENOMEM;
 142         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 143                                 conf->nr_strip_zones, GFP_KERNEL);
 144         if (!conf->strip_zone)
 145                 goto abort;
 146         conf->devlist = kzalloc(sizeof(struct md_rdev*)*
 147                                 conf->nr_strip_zones*mddev->raid_disks,
 148                                 GFP_KERNEL);
 149         if (!conf->devlist)
 150                 goto abort;
 151
 152         /* The first zone must contain all devices, so here we check that
 153          * there is a proper alignment of slots to devices and find them all
 154          */
 155         zone = &conf->strip_zone[0];
 156         cnt = 0;
 157         smallest = NULL;
 158         dev = conf->devlist;
 159         err = -EINVAL;
 160         rdev_for_each(rdev1, mddev) {
 161                 int j = rdev1->raid_disk;
 162
 163                 if (mddev->level == 10) {
 164                         /* taking over a raid10-n2 array */
 165                         j /= 2;
 166                         rdev1->new_raid_disk = j;
 167                 }
 168
 169                 if (mddev->level == 1) {
 170                         /* taiking over a raid1 array-
 171                          * we have only one active disk
 172                          */
 173                         j = 0;
 174                         rdev1->new_raid_disk = j;
 175                 }
 176
 177                 if (j < 0 || j >= mddev->raid_disks) {
 178                         printk(KERN_ERR "md/raid0:%s: bad disk number %d - "
 179                                "aborting!\n", mdname(mddev), j);
 180                         goto abort;
 181                 }
 182                 if (dev[j]) {
 183                         printk(KERN_ERR "md/raid0:%s: multiple devices for %d - "
 184                                "aborting!\n", mdname(mddev), j);
 185                         goto abort;
 186                 }
 187                 dev[j] = rdev1;
 188
 189                 disk_stack_limits(mddev->gendisk, rdev1->bdev,
 190                                   rdev1->data_offset << 9);
 191
 192                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
 193                         conf->has_merge_bvec = 1;
 194
 195                 if (!smallest || (rdev1->sectors < smallest->sectors))
 196                         smallest = rdev1;
 197                 cnt++;
 198         }
 199         if (cnt != mddev->raid_disks) {
 200                 printk(KERN_ERR "md/raid0:%s: too few disks (%d of %d) - "
 201                        "aborting!\n", mdname(mddev), cnt, mddev->raid_disks);
 202                 goto abort;
 203         }
 204         zone->nb_dev = cnt;
 205         zone->zone_end = smallest->sectors * cnt;
 206
 207         curr_zone_end = zone->zone_end;
 208
 209         /* now do the other zones */
 210         for (i = 1; i < conf->nr_strip_zones; i++)
 211         {
 212                 int j;
 213
 214                 zone = conf->strip_zone + i;
 215                 dev = conf->devlist + i * mddev->raid_disks;
 216
 217                 pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
 218                 zone->dev_start = smallest->sectors;
 219                 smallest = NULL;
 220                 c = 0;
 221
 222                 for (j=0; j<cnt; j++) {
 223                         rdev = conf->devlist[j];
 224                         if (rdev->sectors <= zone->dev_start) {
 225                                 pr_debug("md/raid0:%s: checking %s ... nope\n",
 226                                          mdname(mddev),
 227                                          bdevname(rdev->bdev, b));
 228                                 continue;
 229                         }
 230                         pr_debug("md/raid0:%s: checking %s ..."
 231                                  " contained as device %d\n",
 232                                  mdname(mddev),
 233                                  bdevname(rdev->bdev, b), c);
 234                         dev[c] = rdev;
 235                         c++;
 236                         if (!smallest || rdev->sectors < smallest->sectors) {
 237                                 smallest = rdev;
 238                                 pr_debug("md/raid0:%s:  (%llu) is smallest!.\n",
 239                                          mdname(mddev),
 240                                          (unsigned long long)rdev->sectors);
 241                         }
 242                 }
 243
 244                 zone->nb_dev = c;
 245                 sectors = (smallest->sectors - zone->dev_start) * c;
 246                 pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
 247                          mdname(mddev),
 248                          zone->nb_dev, (unsigned long long)sectors);
 249
 250                 curr_zone_end += sectors;
 251                 zone->zone_end = curr_zone_end;
 252
 253                 pr_debug("md/raid0:%s: current zone start: %llu\n",
 254                          mdname(mddev),
 255                          (unsigned long long)smallest->sectors);
 256         }
 257         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
 258         mddev->queue->backing_dev_info.congested_data = mddev;
 259
 260         /*
 261          * now since we have the hard sector sizes, we can make sure
 262          * chunk size is a multiple of that sector size
 263          */
 264         if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
 265                 printk(KERN_ERR "md/raid0:%s: chunk_size of %d not valid\n",
 266                        mdname(mddev),
 267                        mddev->chunk_sectors << 9);
 268                 goto abort;
 269         }
 270
 271         blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 272         blk_queue_io_opt(mddev->queue,
 273                          (mddev->chunk_sectors << 9) * mddev->raid_disks);
 274
 275         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 276         *private_conf = conf;
 277
 278         return 0;
 279 abort:
 280         kfree(conf->strip_zone);
 281         kfree(conf->devlist);
 282         kfree(conf);
 283         *private_conf = NULL;
 284         return err;
 285 }
 286
 287 /* Find the zone which holds a particular offset
 288  * Update *sectorp to be an offset in that zone
 289  */
 290 static struct strip_zone *find_zone(struct r0conf *conf,
 291                                     sector_t *sectorp)
 292 {
 293         int i;
 294         struct strip_zone *z = conf->strip_zone;
 295         sector_t sector = *sectorp;
 296
 297         for (i = 0; i < conf->nr_strip_zones; i++)
 298                 if (sector < z[i].zone_end) {
 299                         if (i)
 300                                 *sectorp = sector - z[i-1].zone_end;
 301                         return z + i;
 302                 }
 303         BUG();
 304 }
 305
 306 /*
 307  * remaps the bio to the target device. we separate two flows.
 308  * power 2 flow and a general flow for the sake of perfromance
 309 */
 310 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 311                                 sector_t sector, sector_t *sector_offset)
 312 {
 313         unsigned int sect_in_chunk;
 314         sector_t chunk;
 315         struct r0conf *conf = mddev->private;
 316         int raid_disks = conf->strip_zone[0].nb_dev;
 317         unsigned int chunk_sects = mddev->chunk_sectors;
 318
 319         if (is_power_of_2(chunk_sects)) {
 320                 int chunksect_bits = ffz(~chunk_sects);
 321                 /* find the sector offset inside the chunk */
 322                 sect_in_chunk  = sector & (chunk_sects - 1);
 323                 sector >>= chunksect_bits;
 324                 /* chunk in zone */
 325                 chunk = *sector_offset;
 326                 /* quotient is the chunk in real device*/
 327                 sector_div(chunk, zone->nb_dev << chunksect_bits);
 328         } else{
 329                 sect_in_chunk = sector_div(sector, chunk_sects);
 330                 chunk = *sector_offset;
 331                 sector_div(chunk, chunk_sects * zone->nb_dev);
 332         }
 333         /*
 334         *  position the bio over the real device
 335         *  real sector = chunk in device + starting of zone
 336         *       + the position in the chunk
 337         */
 338         *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
 339         return conf->devlist[(zone - conf->strip_zone)*raid_disks
 340                              + sector_div(sector, zone->nb_dev)];
 341 }
 342
 343 /**
 344  *      raid0_mergeable_bvec -- tell bio layer if two requests can be merged
 345  *      @q: request queue
 346  *      @bvm: properties of new bio
 347  *      @biovec: the request that could be merged to it.
 348  *
 349  *      Return amount of bytes we can accept at this offset
 350  */
 351 static int raid0_mergeable_bvec(struct request_queue *q,
 352                                 struct bvec_merge_data *bvm,
 353                                 struct bio_vec *biovec)
 354 {
 355         struct mddev *mddev = q->queuedata;
 356         struct r0conf *conf = mddev->private;
 357         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 358         sector_t sector_offset = sector;
 359         int max;
 360         unsigned int chunk_sectors = mddev->chunk_sectors;
 361         unsigned int bio_sectors = bvm->bi_size >> 9;
 362         struct strip_zone *zone;
 363         struct md_rdev *rdev;
 364         struct request_queue *subq;
 365
 366         if (is_power_of_2(chunk_sectors))
 367                 max =  (chunk_sectors - ((sector & (chunk_sectors-1))
 368                                                 + bio_sectors)) << 9;
 369         else
 370                 max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
 371                                                 + bio_sectors)) << 9;
 372         if (max < 0)
 373                 max = 0; /* bio_add cannot handle a negative return */
 374         if (max <= biovec->bv_len && bio_sectors == 0)
 375                 return biovec->bv_len;
 376         if (max < biovec->bv_len)
 377                 /* too small already, no need to check further */
 378                 return max;
 379         if (!conf->has_merge_bvec)
 380                 return max;
 381
 382         /* May need to check subordinate device */
 383         sector = sector_offset;
 384         zone = find_zone(mddev->private, &sector_offset);
 385         rdev = map_sector(mddev, zone, sector, &sector_offset);
 386         subq = bdev_get_queue(rdev->bdev);
 387         if (subq->merge_bvec_fn) {
 388                 bvm->bi_bdev = rdev->bdev;
 389                 bvm->bi_sector = sector_offset + zone->dev_start +
 390                         rdev->data_offset;
 391                 return min(max, subq->merge_bvec_fn(subq, bvm, biovec));
 392         } else
 393                 return max;
 394 }
 395
 396 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 397 {
 398         sector_t array_sectors = 0;
 399         struct md_rdev *rdev;
 400
 401         WARN_ONCE(sectors || raid_disks,
 402                   "%s does not support generic reshape\n", __func__);
 403
 404         rdev_for_each(rdev, mddev)
 405                 array_sectors += rdev->sectors;
 406
 407         return array_sectors;
 408 }
 409
 410 static int raid0_stop(struct mddev *mddev);
 411
 412 static int raid0_run(struct mddev *mddev)
 413 {
 414         struct r0conf *conf;
 415         int ret;
 416
 417         if (mddev->chunk_sectors == 0) {
 418                 printk(KERN_ERR "md/raid0:%s: chunk size must be set.\n",
 419                        mdname(mddev));
 420                 return -EINVAL;
 421         }
 422         if (md_check_no_bitmap(mddev))
 423                 return -EINVAL;
 424         blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 425
 426         /* if private is not null, we are here after takeover */
 427         if (mddev->private == NULL) {
 428                 ret = create_strip_zones(mddev, &conf);
 429                 if (ret < 0)
 430                         return ret;
 431                 mddev->private = conf;
 432         }
 433         conf = mddev->private;
 434
 435         /* calculate array device size */
 436         md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
 437
 438         printk(KERN_INFO "md/raid0:%s: md_size is %llu sectors.\n",
 439                mdname(mddev),
 440                (unsigned long long)mddev->array_sectors);
 441         /* calculate the max read-ahead size.
 442          * For read-ahead of large files to be effective, we need to
 443          * readahead at least twice a whole stripe. i.e. number of devices
 444          * multiplied by chunk size times 2.
 445          * If an individual device has an ra_pages greater than the
 446          * chunk size, then we will not drive that device as hard as it
 447          * wants.  We consider this a configuration error: a larger
 448          * chunksize should be used in that case.
 449          */
 450         {
 451                 int stripe = mddev->raid_disks *
 452                         (mddev->chunk_sectors << 9) / PAGE_SIZE;
 453                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 454                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 455         }
 456
 457         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 458         dump_zones(mddev);
 459
 460         ret = md_integrity_register(mddev);
 461         if (ret)
 462                 raid0_stop(mddev);
 463
 464         return ret;
 465 }
 466
 467 static int raid0_stop(struct mddev *mddev)
 468 {
 469         struct r0conf *conf = mddev->private;
 470
 471         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 472         kfree(conf->strip_zone);
 473         kfree(conf->devlist);
 474         kfree(conf);
 475         mddev->private = NULL;
 476         return 0;
 477 }
 478
 479 /*
 480  * Is io distribute over 1 or more chunks ?
 481 */
 482 static inline int is_io_in_chunk_boundary(struct mddev *mddev,
 483                         unsigned int chunk_sects, struct bio *bio)
 484 {
 485         if (likely(is_power_of_2(chunk_sects))) {
 486                 return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
 487                                         + (bio->bi_size >> 9));
 488         } else{
 489                 sector_t sector = bio->bi_sector;
 490                 return chunk_sects >= (sector_div(sector, chunk_sects)
 491                                                 + (bio->bi_size >> 9));
 492         }
 493 }
 494
 495 static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 496 {
 497         unsigned int chunk_sects;
 498         sector_t sector_offset;
 499         struct strip_zone *zone;
 500         struct md_rdev *tmp_dev;
 501
 502         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 503                 md_flush_request(mddev, bio);
 504                 return;
 505         }
 506
 507         chunk_sects = mddev->chunk_sectors;
 508         if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
 509                 sector_t sector = bio->bi_sector;
 510                 struct bio_pair *bp;
 511                 /* Sanity check -- queue functions should prevent this happening */
 512                 if (bio->bi_vcnt != 1 ||
 513                     bio->bi_idx != 0)
 514                         goto bad_map;
 515                 /* This is a one page bio that upper layers
 516                  * refuse to split for us, so we need to split it.
 517                  */
 518                 if (likely(is_power_of_2(chunk_sects)))
 519                         bp = bio_split(bio, chunk_sects - (sector &
 520                                                            (chunk_sects-1)));
 521                 else
 522                         bp = bio_split(bio, chunk_sects -
 523                                        sector_div(sector, chunk_sects));
 524                 raid0_make_request(mddev, &bp->bio1);
 525                 raid0_make_request(mddev, &bp->bio2);
 526                 bio_pair_release(bp);
 527                 return;
 528         }
 529
 530         sector_offset = bio->bi_sector;
 531         zone = find_zone(mddev->private, &sector_offset);
 532         tmp_dev = map_sector(mddev, zone, bio->bi_sector,
 533                              &sector_offset);
 534         bio->bi_bdev = tmp_dev->bdev;
 535         bio->bi_sector = sector_offset + zone->dev_start +
 536                 tmp_dev->data_offset;
 537
 538         generic_make_request(bio);
 539         return;
 540
 541 bad_map:
 542         printk("md/raid0:%s: make_request bug: can't convert block across chunks"
 543                " or bigger than %dk %llu %d\n",
 544                mdname(mddev), chunk_sects / 2,
 545                (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 546
 547         bio_io_error(bio);
 548         return;
 549 }
 550
 551 static void raid0_status(struct seq_file *seq, struct mddev *mddev)
 552 {
 553         seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 554         return;
 555 }
 556
 557 static void *raid0_takeover_raid45(struct mddev *mddev)
 558 {
 559         struct md_rdev *rdev;
 560         struct r0conf *priv_conf;
 561
 562         if (mddev->degraded != 1) {
 563                 printk(KERN_ERR "md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
 564                        mdname(mddev),
 565                        mddev->degraded);
 566                 return ERR_PTR(-EINVAL);
 567         }
 568
 569         rdev_for_each(rdev, mddev) {
 570                 /* check slot number for a disk */
 571                 if (rdev->raid_disk == mddev->raid_disks-1) {
 572                         printk(KERN_ERR "md/raid0:%s: raid5 must have missing parity disk!\n",
 573                                mdname(mddev));
 574                         return ERR_PTR(-EINVAL);
 575                 }
 576         }
 577
 578         /* Set new parameters */
 579         mddev->new_level = 0;
 580         mddev->new_layout = 0;
 581         mddev->new_chunk_sectors = mddev->chunk_sectors;
 582         mddev->raid_disks--;
 583         mddev->delta_disks = -1;
 584         /* make sure it will be not marked as dirty */
 585         mddev->recovery_cp = MaxSector;
 586
 587         create_strip_zones(mddev, &priv_conf);
 588         return priv_conf;
 589 }
 590
 591 static void *raid0_takeover_raid10(struct mddev *mddev)
 592 {
 593         struct r0conf *priv_conf;
 594
 595         /* Check layout:
 596          *  - far_copies must be 1
 597          *  - near_copies must be 2
 598          *  - disks number must be even
 599          *  - all mirrors must be already degraded
 600          */
 601         if (mddev->layout != ((1 << 8) + 2)) {
 602                 printk(KERN_ERR "md/raid0:%s:: Raid0 cannot takover layout: 0x%x\n",
 603                        mdname(mddev),
 604                        mddev->layout);
 605                 return ERR_PTR(-EINVAL);
 606         }
 607         if (mddev->raid_disks & 1) {
 608                 printk(KERN_ERR "md/raid0:%s: Raid0 cannot takover Raid10 with odd disk number.\n",
 609                        mdname(mddev));
 610                 return ERR_PTR(-EINVAL);
 611         }
 612         if (mddev->degraded != (mddev->raid_disks>>1)) {
 613                 printk(KERN_ERR "md/raid0:%s: All mirrors must be already degraded!\n",
 614                        mdname(mddev));
 615                 return ERR_PTR(-EINVAL);
 616         }
 617
 618         /* Set new parameters */
 619         mddev->new_level = 0;
 620         mddev->new_layout = 0;
 621         mddev->new_chunk_sectors = mddev->chunk_sectors;
 622         mddev->delta_disks = - mddev->raid_disks / 2;
 623         mddev->raid_disks += mddev->delta_disks;
 624         mddev->degraded = 0;
 625         /* make sure it will be not marked as dirty */
 626         mddev->recovery_cp = MaxSector;
 627
 628         create_strip_zones(mddev, &priv_conf);
 629         return priv_conf;
 630 }
 631
 632 static void *raid0_takeover_raid1(struct mddev *mddev)
 633 {
 634         struct r0conf *priv_conf;
 635         int chunksect;
 636
 637         /* Check layout:
 638          *  - (N - 1) mirror drives must be already faulty
 639          */
 640         if ((mddev->raid_disks - 1) != mddev->degraded) {
 641                 printk(KERN_ERR "md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
 642                        mdname(mddev));
 643                 return ERR_PTR(-EINVAL);
 644         }
 645
 646         /*
 647          * a raid1 doesn't have the notion of chunk size, so
 648          * figure out the largest suitable size we can use.
 649          */
 650         chunksect = 64 * 2; /* 64K by default */
 651
 652         /* The array must be an exact multiple of chunksize */
 653         while (chunksect && (mddev->array_sectors & (chunksect - 1)))
 654                 chunksect >>= 1;
 655
 656         if ((chunksect << 9) < PAGE_SIZE)
 657                 /* array size does not allow a suitable chunk size */
 658                 return ERR_PTR(-EINVAL);
 659
 660         /* Set new parameters */
 661         mddev->new_level = 0;
 662         mddev->new_layout = 0;
 663         mddev->new_chunk_sectors = chunksect;
 664         mddev->chunk_sectors = chunksect;
 665         mddev->delta_disks = 1 - mddev->raid_disks;
 666         mddev->raid_disks = 1;
 667         /* make sure it will be not marked as dirty */
 668         mddev->recovery_cp = MaxSector;
 669
 670         create_strip_zones(mddev, &priv_conf);
 671         return priv_conf;
 672 }
 673
 674 static void *raid0_takeover(struct mddev *mddev)
 675 {
 676         /* raid0 can take over:
 677          *  raid4 - if all data disks are active.
 678          *  raid5 - providing it is Raid4 layout and one disk is faulty
 679          *  raid10 - assuming we have all necessary active disks
 680          *  raid1 - with (N -1) mirror drives faulty
 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         .stop           = raid0_stop,
 717         .status         = raid0_status,
 718         .size           = raid0_size,
 719         .takeover       = raid0_takeover,
 720         .quiesce        = raid0_quiesce,
 721 };
 722
 723 static int __init raid0_init (void)
 724 {
 725         return register_md_personality (&raid0_personality);
 726 }
 727
 728 static void raid0_exit (void)
 729 {
 730         unregister_md_personality (&raid0_personality);
 731 }
 732
 733 module_init(raid0_init);
 734 module_exit(raid0_exit);
 735 MODULE_LICENSE("GPL");
 736 MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
 737 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 738 MODULE_ALIAS("md-raid0");
 739 MODULE_ALIAS("md-level-0");