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 for (i=0; i< nb_zone; i++) { 335 conf->hash_table[i] = conf->strip_zone + cur; 336 while (size <= conf->hash_spacing) { 337 cur++; 338 size += conf->strip_zone[cur].size; 339 } 340 size -= conf->hash_spacing; 341 } 342 if (conf->preshift) { 343 conf->hash_spacing >>= conf->preshift; 344 /* round hash_spacing up so when we divide by it, we 345 * err on the side of too-low, which is safest 346 */ 347 conf->hash_spacing++; 348 } 349 350 /* calculate the max read-ahead size. 351 * For read-ahead of large files to be effective, we need to 352 * readahead at least twice a whole stripe. i.e. number of devices 353 * multiplied by chunk size times 2. 354 * If an individual device has an ra_pages greater than the 355 * chunk size, then we will not drive that device as hard as it 356 * wants. We consider this a configuration error: a larger 357 * chunksize should be used in that case. 358 */ 359 { 360 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE; 361 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 362 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 363 } 364 365 366 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 367 return 0; 368 369 out_free_conf: 370 kfree(conf->strip_zone); 371 kfree(conf->devlist); 372 kfree(conf); 373 mddev->private = NULL; 374 out: 375 return -ENOMEM; 376 } 377 378 static int raid0_stop (mddev_t *mddev) 379 { 380 raid0_conf_t *conf = mddev_to_conf(mddev); 381 382 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 383 kfree(conf->hash_table); 384 conf->hash_table = NULL; 385 kfree(conf->strip_zone); 386 conf->strip_zone = NULL; 387 kfree(conf); 388 mddev->private = NULL; 389 390 return 0; 391 } 392 393 static int raid0_make_request (request_queue_t *q, struct bio *bio) 394 { 395 mddev_t *mddev = q->queuedata; 396 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects; 397 raid0_conf_t *conf = mddev_to_conf(mddev); 398 struct strip_zone *zone; 399 mdk_rdev_t *tmp_dev; 400 unsigned long chunk; 401 sector_t block, rsect; 402 const int rw = bio_data_dir(bio); 403 404 if (unlikely(bio_barrier(bio))) { 405 bio_endio(bio, bio->bi_size, -EOPNOTSUPP); 406 return 0; 407 } 408 409 disk_stat_inc(mddev->gendisk, ios[rw]); 410 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio)); 411 412 chunk_size = mddev->chunk_size >> 10; 413 chunk_sects = mddev->chunk_size >> 9; 414 chunksize_bits = ffz(~chunk_size); 415 block = bio->bi_sector >> 1; 416 417 418 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 419 struct bio_pair *bp; 420 /* Sanity check -- queue functions should prevent this happening */ 421 if (bio->bi_vcnt != 1 || 422 bio->bi_idx != 0) 423 goto bad_map; 424 /* This is a one page bio that upper layers 425 * refuse to split for us, so we need to split it. 426 */ 427 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) ); 428 if (raid0_make_request(q, &bp->bio1)) 429 generic_make_request(&bp->bio1); 430 if (raid0_make_request(q, &bp->bio2)) 431 generic_make_request(&bp->bio2); 432 433 bio_pair_release(bp); 434 return 0; 435 } 436 437 438 { 439 sector_t x = block >> conf->preshift; 440 sector_div(x, (u32)conf->hash_spacing); 441 zone = conf->hash_table[x]; 442 } 443 444 while (block >= (zone->zone_offset + zone->size)) 445 zone++; 446 447 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1); 448 449 450 { 451 sector_t x = (block - zone->zone_offset) >> chunksize_bits; 452 453 sector_div(x, zone->nb_dev); 454 chunk = x; 455 BUG_ON(x != (sector_t)chunk); 456 457 x = block >> chunksize_bits; 458 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 459 } 460 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1) 461 + sect_in_chunk; 462 463 bio->bi_bdev = tmp_dev->bdev; 464 bio->bi_sector = rsect + tmp_dev->data_offset; 465 466 /* 467 * Let the main block layer submit the IO and resolve recursion: 468 */ 469 return 1; 470 471 bad_map: 472 printk("raid0_make_request bug: can't convert block across chunks" 473 " or bigger than %dk %llu %d\n", chunk_size, 474 (unsigned long long)bio->bi_sector, bio->bi_size >> 10); 475 476 bio_io_error(bio, bio->bi_size); 477 return 0; 478 } 479 480 static void raid0_status (struct seq_file *seq, mddev_t *mddev) 481 { 482 #undef MD_DEBUG 483 #ifdef MD_DEBUG 484 int j, k, h; 485 char b[BDEVNAME_SIZE]; 486 raid0_conf_t *conf = mddev_to_conf(mddev); 487 488 h = 0; 489 for (j = 0; j < conf->nr_strip_zones; j++) { 490 seq_printf(seq, " z%d", j); 491 if (conf->hash_table[h] == conf->strip_zone+j) 492 seq_printf("(h%d)", h++); 493 seq_printf(seq, "=["); 494 for (k = 0; k < conf->strip_zone[j].nb_dev; k++) 495 seq_printf (seq, "%s/", bdevname( 496 conf->strip_zone[j].dev[k]->bdev,b)); 497 498 seq_printf (seq, "] zo=%d do=%d s=%d\n", 499 conf->strip_zone[j].zone_offset, 500 conf->strip_zone[j].dev_offset, 501 conf->strip_zone[j].size); 502 } 503 #endif 504 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); 505 return; 506 } 507 508 static struct mdk_personality raid0_personality= 509 { 510 .name = "raid0", 511 .level = 0, 512 .owner = THIS_MODULE, 513 .make_request = raid0_make_request, 514 .run = raid0_run, 515 .stop = raid0_stop, 516 .status = raid0_status, 517 }; 518 519 static int __init raid0_init (void) 520 { 521 return register_md_personality (&raid0_personality); 522 } 523 524 static void raid0_exit (void) 525 { 526 unregister_md_personality (&raid0_personality); 527 } 528 529 module_init(raid0_init); 530 module_exit(raid0_exit); 531 MODULE_LICENSE("GPL"); 532 MODULE_ALIAS("md-personality-2"); /* RAID0 */ 533 MODULE_ALIAS("md-raid0"); 534 MODULE_ALIAS("md-level-0"); 535