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