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/module.h>
  22 #include <linux/raid/raid0.h>
  23
  24 #define MAJOR_NR MD_MAJOR
  25 #define MD_DRIVER
  26 #define MD_PERSONALITY
  27
  28 static void raid0_unplug(struct request_queue *q)
  29 {
  30         mddev_t *mddev = q->queuedata;
  31         raid0_conf_t *conf = mddev_to_conf(mddev);
  32         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
  33         int i;
  34
  35         for (i=0; i<mddev->raid_disks; i++) {
  36                 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
  37
  38                 if (r_queue->unplug_fn)
  39                         r_queue->unplug_fn(r_queue);
  40         }
  41 }
  42
  43 static int raid0_issue_flush(struct request_queue *q, struct gendisk *disk,
  44                              sector_t *error_sector)
  45 {
  46         mddev_t *mddev = q->queuedata;
  47         raid0_conf_t *conf = mddev_to_conf(mddev);
  48         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
  49         int i, ret = 0;
  50
  51         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
  52                 struct block_device *bdev = devlist[i]->bdev;
  53                 struct request_queue *r_queue = bdev_get_queue(bdev);
  54
  55                 if (!r_queue->issue_flush_fn)
  56                         ret = -EOPNOTSUPP;
  57                 else
  58                         ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
  59         }
  60         return ret;
  61 }
  62
  63 static int raid0_congested(void *data, int bits)
  64 {
  65         mddev_t *mddev = data;
  66         raid0_conf_t *conf = mddev_to_conf(mddev);
  67         mdk_rdev_t **devlist = conf->strip_zone[0].dev;
  68         int i, ret = 0;
  69
  70         for (i = 0; i < mddev->raid_disks && !ret ; i++) {
  71                 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
  72
  73                 ret |= bdi_congested(&q->backing_dev_info, bits);
  74         }
  75         return ret;
  76 }
  77
  78
  79 static int create_strip_zones (mddev_t *mddev)
  80 {
  81         int i, c, j;
  82         sector_t current_offset, curr_zone_offset;
  83         sector_t min_spacing;
  84         raid0_conf_t *conf = mddev_to_conf(mddev);
  85         mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
  86         struct list_head *tmp1, *tmp2;
  87         struct strip_zone *zone;
  88         int cnt;
  89         char b[BDEVNAME_SIZE];
  90
  91         /*
  92          * The number of 'same size groups'
  93          */
  94         conf->nr_strip_zones = 0;
  95
  96         ITERATE_RDEV(mddev,rdev1,tmp1) {
  97                 printk("raid0: looking at %s\n",
  98                         bdevname(rdev1->bdev,b));
  99                 c = 0;
 100                 ITERATE_RDEV(mddev,rdev2,tmp2) {
 101                         printk("raid0:   comparing %s(%llu)",
 102                                bdevname(rdev1->bdev,b),
 103                                (unsigned long long)rdev1->size);
 104                         printk(" with %s(%llu)\n",
 105                                bdevname(rdev2->bdev,b),
 106                                (unsigned long long)rdev2->size);
 107                         if (rdev2 == rdev1) {
 108                                 printk("raid0:   END\n");
 109                                 break;
 110                         }
 111                         if (rdev2->size == rdev1->size)
 112                         {
 113                                 /*
 114                                  * Not unique, don't count it as a new
 115                                  * group
 116                                  */
 117                                 printk("raid0:   EQUAL\n");
 118                                 c = 1;
 119                                 break;
 120                         }
 121                         printk("raid0:   NOT EQUAL\n");
 122                 }
 123                 if (!c) {
 124                         printk("raid0:   ==> UNIQUE\n");
 125                         conf->nr_strip_zones++;
 126                         printk("raid0: %d zones\n", conf->nr_strip_zones);
 127                 }
 128         }
 129         printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);
 130
 131         conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 132                                 conf->nr_strip_zones, GFP_KERNEL);
 133         if (!conf->strip_zone)
 134                 return 1;
 135         conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
 136                                 conf->nr_strip_zones*mddev->raid_disks,
 137                                 GFP_KERNEL);
 138         if (!conf->devlist)
 139                 return 1;
 140
 141         /* The first zone must contain all devices, so here we check that
 142          * there is a proper alignment of slots to devices and find them all
 143          */
 144         zone = &conf->strip_zone[0];
 145         cnt = 0;
 146         smallest = NULL;
 147         zone->dev = conf->devlist;
 148         ITERATE_RDEV(mddev, rdev1, tmp1) {
 149                 int j = rdev1->raid_disk;
 150
 151                 if (j < 0 || j >= mddev->raid_disks) {
 152                         printk("raid0: bad disk number %d - aborting!\n", j);
 153                         goto abort;
 154                 }
 155                 if (zone->dev[j]) {
 156                         printk("raid0: multiple devices for %d - aborting!\n",
 157                                 j);
 158                         goto abort;
 159                 }
 160                 zone->dev[j] = rdev1;
 161
 162                 blk_queue_stack_limits(mddev->queue,
 163                                        rdev1->bdev->bd_disk->queue);
 164                 /* as we don't honour merge_bvec_fn, we must never risk
 165                  * violating it, so limit ->max_sector to one PAGE, as
 166                  * a one page request is never in violation.
 167                  */
 168
 169                 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
 170                     mddev->queue->max_sectors > (PAGE_SIZE>>9))
 171                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 172
 173                 if (!smallest || (rdev1->size <smallest->size))
 174                         smallest = rdev1;
 175                 cnt++;
 176         }
 177         if (cnt != mddev->raid_disks) {
 178                 printk("raid0: too few disks (%d of %d) - aborting!\n",
 179                         cnt, mddev->raid_disks);
 180                 goto abort;
 181         }
 182         zone->nb_dev = cnt;
 183         zone->size = smallest->size * cnt;
 184         zone->zone_offset = 0;
 185
 186         current_offset = smallest->size;
 187         curr_zone_offset = zone->size;
 188
 189         /* now do the other zones */
 190         for (i = 1; i < conf->nr_strip_zones; i++)
 191         {
 192                 zone = conf->strip_zone + i;
 193                 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
 194
 195                 printk("raid0: zone %d\n", i);
 196                 zone->dev_offset = current_offset;
 197                 smallest = NULL;
 198                 c = 0;
 199
 200                 for (j=0; j<cnt; j++) {
 201                         char b[BDEVNAME_SIZE];
 202                         rdev = conf->strip_zone[0].dev[j];
 203                         printk("raid0: checking %s ...", bdevname(rdev->bdev,b));
 204                         if (rdev->size > current_offset)
 205                         {
 206                                 printk(" contained as device %d\n", c);
 207                                 zone->dev[c] = rdev;
 208                                 c++;
 209                                 if (!smallest || (rdev->size <smallest->size)) {
 210                                         smallest = rdev;
 211                                         printk("  (%llu) is smallest!.\n",
 212                                                 (unsigned long long)rdev->size);
 213                                 }
 214                         } else
 215                                 printk(" nope.\n");
 216                 }
 217
 218                 zone->nb_dev = c;
 219                 zone->size = (smallest->size - current_offset) * c;
 220                 printk("raid0: zone->nb_dev: %d, size: %llu\n",
 221                         zone->nb_dev, (unsigned long long)zone->size);
 222
 223                 zone->zone_offset = curr_zone_offset;
 224                 curr_zone_offset += zone->size;
 225
 226                 current_offset = smallest->size;
 227                 printk("raid0: current zone offset: %llu\n",
 228                         (unsigned long long)current_offset);
 229         }
 230
 231         /* Now find appropriate hash spacing.
 232          * We want a number which causes most hash entries to cover
 233          * at most two strips, but the hash table must be at most
 234          * 1 PAGE.  We choose the smallest strip, or contiguous collection
 235          * of strips, that has big enough size.  We never consider the last
 236          * strip though as it's size has no bearing on the efficacy of the hash
 237          * table.
 238          */
 239         conf->hash_spacing = curr_zone_offset;
 240         min_spacing = curr_zone_offset;
 241         sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
 242         for (i=0; i < conf->nr_strip_zones-1; i++) {
 243                 sector_t sz = 0;
 244                 for (j=i; j<conf->nr_strip_zones-1 &&
 245                              sz < min_spacing ; j++)
 246                         sz += conf->strip_zone[j].size;
 247                 if (sz >= min_spacing && sz < conf->hash_spacing)
 248                         conf->hash_spacing = sz;
 249         }
 250
 251         mddev->queue->unplug_fn = raid0_unplug;
 252
 253         mddev->queue->issue_flush_fn = raid0_issue_flush;
 254         mddev->queue->backing_dev_info.congested_fn = raid0_congested;
 255         mddev->queue->backing_dev_info.congested_data = mddev;
 256
 257         printk("raid0: done.\n");
 258         return 0;
 259  abort:
 260         return 1;
 261 }
 262
 263 /**
 264  *      raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
 265  *      @q: request queue
 266  *      @bio: the buffer head that's been built up so far
 267  *      @biovec: the request that could be merged to it.
 268  *
 269  *      Return amount of bytes we can accept at this offset
 270  */
 271 static int raid0_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec)
 272 {
 273         mddev_t *mddev = q->queuedata;
 274         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
 275         int max;
 276         unsigned int chunk_sectors = mddev->chunk_size >> 9;
 277         unsigned int bio_sectors = bio->bi_size >> 9;
 278
 279         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
 280         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
 281         if (max <= biovec->bv_len && bio_sectors == 0)
 282                 return biovec->bv_len;
 283         else
 284                 return max;
 285 }
 286
 287 static int raid0_run (mddev_t *mddev)
 288 {
 289         unsigned  cur=0, i=0, nb_zone;
 290         s64 size;
 291         raid0_conf_t *conf;
 292         mdk_rdev_t *rdev;
 293         struct list_head *tmp;
 294
 295         if (mddev->chunk_size == 0) {
 296                 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
 297                 return -EINVAL;
 298         }
 299         printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
 300                mdname(mddev),
 301                mddev->chunk_size >> 9,
 302                (mddev->chunk_size>>1)-1);
 303         blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
 304         blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
 305
 306         conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
 307         if (!conf)
 308                 goto out;
 309         mddev->private = (void *)conf;
 310
 311         conf->strip_zone = NULL;
 312         conf->devlist = NULL;
 313         if (create_strip_zones (mddev))
 314                 goto out_free_conf;
 315
 316         /* calculate array device size */
 317         mddev->array_size = 0;
 318         ITERATE_RDEV(mddev,rdev,tmp)
 319                 mddev->array_size += rdev->size;
 320
 321         printk("raid0 : md_size is %llu blocks.\n",
 322                 (unsigned long long)mddev->array_size);
 323         printk("raid0 : conf->hash_spacing is %llu blocks.\n",
 324                 (unsigned long long)conf->hash_spacing);
 325         {
 326                 sector_t s = mddev->array_size;
 327                 sector_t space = conf->hash_spacing;
 328                 int round;
 329                 conf->preshift = 0;
 330                 if (sizeof(sector_t) > sizeof(u32)) {
 331                         /*shift down space and s so that sector_div will work */
 332                         while (space > (sector_t) (~(u32)0)) {
 333                                 s >>= 1;
 334                                 space >>= 1;
 335                                 s += 1; /* force round-up */
 336                                 conf->preshift++;
 337                         }
 338                 }
 339                 round = sector_div(s, (u32)space) ? 1 : 0;
 340                 nb_zone = s + round;
 341         }
 342         printk("raid0 : nb_zone is %d.\n", nb_zone);
 343
 344         printk("raid0 : Allocating %Zd bytes for hash.\n",
 345                                 nb_zone*sizeof(struct strip_zone*));
 346         conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
 347         if (!conf->hash_table)
 348                 goto out_free_conf;
 349         size = conf->strip_zone[cur].size;
 350
 351         conf->hash_table[0] = conf->strip_zone + cur;
 352         for (i=1; i< nb_zone; i++) {
 353                 while (size <= conf->hash_spacing) {
 354                         cur++;
 355                         size += conf->strip_zone[cur].size;
 356                 }
 357                 size -= conf->hash_spacing;
 358                 conf->hash_table[i] = conf->strip_zone + cur;
 359         }
 360         if (conf->preshift) {
 361                 conf->hash_spacing >>= conf->preshift;
 362                 /* round hash_spacing up so when we divide by it, we
 363                  * err on the side of too-low, which is safest
 364                  */
 365                 conf->hash_spacing++;
 366         }
 367
 368         /* calculate the max read-ahead size.
 369          * For read-ahead of large files to be effective, we need to
 370          * readahead at least twice a whole stripe. i.e. number of devices
 371          * multiplied by chunk size times 2.
 372          * If an individual device has an ra_pages greater than the
 373          * chunk size, then we will not drive that device as hard as it
 374          * wants.  We consider this a configuration error: a larger
 375          * chunksize should be used in that case.
 376          */
 377         {
 378                 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
 379                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 380                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 381         }
 382
 383
 384         blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 385         return 0;
 386
 387 out_free_conf:
 388         kfree(conf->strip_zone);
 389         kfree(conf->devlist);
 390         kfree(conf);
 391         mddev->private = NULL;
 392 out:
 393         return -ENOMEM;
 394 }
 395
 396 static int raid0_stop (mddev_t *mddev)
 397 {
 398         raid0_conf_t *conf = mddev_to_conf(mddev);
 399
 400         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 401         kfree(conf->hash_table);
 402         conf->hash_table = NULL;
 403         kfree(conf->strip_zone);
 404         conf->strip_zone = NULL;
 405         kfree(conf);
 406         mddev->private = NULL;
 407
 408         return 0;
 409 }
 410
 411 static int raid0_make_request (struct request_queue *q, struct bio *bio)
 412 {
 413         mddev_t *mddev = q->queuedata;
 414         unsigned int sect_in_chunk, chunksize_bits,  chunk_size, chunk_sects;
 415         raid0_conf_t *conf = mddev_to_conf(mddev);
 416         struct strip_zone *zone;
 417         mdk_rdev_t *tmp_dev;
 418         sector_t chunk;
 419         sector_t block, rsect;
 420         const int rw = bio_data_dir(bio);
 421
 422         if (unlikely(bio_barrier(bio))) {
 423                 bio_endio(bio, -EOPNOTSUPP);
 424                 return 0;
 425         }
 426
 427         disk_stat_inc(mddev->gendisk, ios[rw]);
 428         disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
 429
 430         chunk_size = mddev->chunk_size >> 10;
 431         chunk_sects = mddev->chunk_size >> 9;
 432         chunksize_bits = ffz(~chunk_size);
 433         block = bio->bi_sector >> 1;
 434
 435
 436         if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
 437                 struct bio_pair *bp;
 438                 /* Sanity check -- queue functions should prevent this happening */
 439                 if (bio->bi_vcnt != 1 ||
 440                     bio->bi_idx != 0)
 441                         goto bad_map;
 442                 /* This is a one page bio that upper layers
 443                  * refuse to split for us, so we need to split it.
 444                  */
 445                 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
 446                 if (raid0_make_request(q, &bp->bio1))
 447                         generic_make_request(&bp->bio1);
 448                 if (raid0_make_request(q, &bp->bio2))
 449                         generic_make_request(&bp->bio2);
 450
 451                 bio_pair_release(bp);
 452                 return 0;
 453         }
 454
 455
 456         {
 457                 sector_t x = block >> conf->preshift;
 458                 sector_div(x, (u32)conf->hash_spacing);
 459                 zone = conf->hash_table[x];
 460         }
 461
 462         while (block >= (zone->zone_offset + zone->size))
 463                 zone++;
 464
 465         sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);
 466
 467
 468         {
 469                 sector_t x =  (block - zone->zone_offset) >> chunksize_bits;
 470
 471                 sector_div(x, zone->nb_dev);
 472                 chunk = x;
 473
 474                 x = block >> chunksize_bits;
 475                 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
 476         }
 477         rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
 478                 + sect_in_chunk;
 479
 480         bio->bi_bdev = tmp_dev->bdev;
 481         bio->bi_sector = rsect + tmp_dev->data_offset;
 482
 483         /*
 484          * Let the main block layer submit the IO and resolve recursion:
 485          */
 486         return 1;
 487
 488 bad_map:
 489         printk("raid0_make_request bug: can't convert block across chunks"
 490                 " or bigger than %dk %llu %d\n", chunk_size,
 491                 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 492
 493         bio_io_error(bio);
 494         return 0;
 495 }
 496
 497 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
 498 {
 499 #undef MD_DEBUG
 500 #ifdef MD_DEBUG
 501         int j, k, h;
 502         char b[BDEVNAME_SIZE];
 503         raid0_conf_t *conf = mddev_to_conf(mddev);
 504
 505         h = 0;
 506         for (j = 0; j < conf->nr_strip_zones; j++) {
 507                 seq_printf(seq, "      z%d", j);
 508                 if (conf->hash_table[h] == conf->strip_zone+j)
 509                         seq_printf("(h%d)", h++);
 510                 seq_printf(seq, "=[");
 511                 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
 512                         seq_printf (seq, "%s/", bdevname(
 513                                 conf->strip_zone[j].dev[k]->bdev,b));
 514
 515                 seq_printf (seq, "] zo=%d do=%d s=%d\n",
 516                                 conf->strip_zone[j].zone_offset,
 517                                 conf->strip_zone[j].dev_offset,
 518                                 conf->strip_zone[j].size);
 519         }
 520 #endif
 521         seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
 522         return;
 523 }
 524
 525 static struct mdk_personality raid0_personality=
 526 {
 527         .name           = "raid0",
 528         .level          = 0,
 529         .owner          = THIS_MODULE,
 530         .make_request   = raid0_make_request,
 531         .run            = raid0_run,
 532         .stop           = raid0_stop,
 533         .status         = raid0_status,
 534 };
 535
 536 static int __init raid0_init (void)
 537 {
 538         return register_md_personality (&raid0_personality);
 539 }
 540
 541 static void raid0_exit (void)
 542 {
 543         unregister_md_personality (&raid0_personality);
 544 }
 545
 546 module_init(raid0_init);
 547 module_exit(raid0_exit);
 548 MODULE_LICENSE("GPL");
 549 MODULE_ALIAS("md-personality-2"); /* RAID0 */
 550 MODULE_ALIAS("md-raid0");
 551 MODULE_ALIAS("md-level-0");