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 = kmalloc(sizeof(struct strip_zone)* 117 conf->nr_strip_zones, GFP_KERNEL); 118 if (!conf->strip_zone) 119 return 1; 120 conf->devlist = kmalloc(sizeof(mdk_rdev_t*)* 121 conf->nr_strip_zones*mddev->raid_disks, 122 GFP_KERNEL); 123 if (!conf->devlist) 124 return 1; 125 126 memset(conf->strip_zone, 0,sizeof(struct strip_zone)* 127 conf->nr_strip_zones); 128 memset(conf->devlist, 0, 129 sizeof(mdk_rdev_t*) * conf->nr_strip_zones * mddev->raid_disks); 130 131 /* The first zone must contain all devices, so here we check that 132 * there is a proper alignment of slots to devices and find them all 133 */ 134 zone = &conf->strip_zone[0]; 135 cnt = 0; 136 smallest = NULL; 137 zone->dev = conf->devlist; 138 ITERATE_RDEV(mddev, rdev1, tmp1) { 139 int j = rdev1->raid_disk; 140 141 if (j < 0 || j >= mddev->raid_disks) { 142 printk("raid0: bad disk number %d - aborting!\n", j); 143 goto abort; 144 } 145 if (zone->dev[j]) { 146 printk("raid0: multiple devices for %d - aborting!\n", 147 j); 148 goto abort; 149 } 150 zone->dev[j] = rdev1; 151 152 blk_queue_stack_limits(mddev->queue, 153 rdev1->bdev->bd_disk->queue); 154 /* as we don't honour merge_bvec_fn, we must never risk 155 * violating it, so limit ->max_sector to one PAGE, as 156 * a one page request is never in violation. 157 */ 158 159 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && 160 mddev->queue->max_sectors > (PAGE_SIZE>>9)) 161 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); 162 163 if (!smallest || (rdev1->size <smallest->size)) 164 smallest = rdev1; 165 cnt++; 166 } 167 if (cnt != mddev->raid_disks) { 168 printk("raid0: too few disks (%d of %d) - aborting!\n", 169 cnt, mddev->raid_disks); 170 goto abort; 171 } 172 zone->nb_dev = cnt; 173 zone->size = smallest->size * cnt; 174 zone->zone_offset = 0; 175 176 current_offset = smallest->size; 177 curr_zone_offset = zone->size; 178 179 /* now do the other zones */ 180 for (i = 1; i < conf->nr_strip_zones; i++) 181 { 182 zone = conf->strip_zone + i; 183 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks; 184 185 printk("raid0: zone %d\n", i); 186 zone->dev_offset = current_offset; 187 smallest = NULL; 188 c = 0; 189 190 for (j=0; j<cnt; j++) { 191 char b[BDEVNAME_SIZE]; 192 rdev = conf->strip_zone[0].dev[j]; 193 printk("raid0: checking %s ...", bdevname(rdev->bdev,b)); 194 if (rdev->size > current_offset) 195 { 196 printk(" contained as device %d\n", c); 197 zone->dev[c] = rdev; 198 c++; 199 if (!smallest || (rdev->size <smallest->size)) { 200 smallest = rdev; 201 printk(" (%llu) is smallest!.\n", 202 (unsigned long long)rdev->size); 203 } 204 } else 205 printk(" nope.\n"); 206 } 207 208 zone->nb_dev = c; 209 zone->size = (smallest->size - current_offset) * c; 210 printk("raid0: zone->nb_dev: %d, size: %llu\n", 211 zone->nb_dev, (unsigned long long)zone->size); 212 213 zone->zone_offset = curr_zone_offset; 214 curr_zone_offset += zone->size; 215 216 current_offset = smallest->size; 217 printk("raid0: current zone offset: %llu\n", 218 (unsigned long long)current_offset); 219 } 220 221 /* Now find appropriate hash spacing. 222 * We want a number which causes most hash entries to cover 223 * at most two strips, but the hash table must be at most 224 * 1 PAGE. We choose the smallest strip, or contiguous collection 225 * of strips, that has big enough size. We never consider the last 226 * strip though as it's size has no bearing on the efficacy of the hash 227 * table. 228 */ 229 conf->hash_spacing = curr_zone_offset; 230 min_spacing = curr_zone_offset; 231 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*)); 232 for (i=0; i < conf->nr_strip_zones-1; i++) { 233 sector_t sz = 0; 234 for (j=i; j<conf->nr_strip_zones-1 && 235 sz < min_spacing ; j++) 236 sz += conf->strip_zone[j].size; 237 if (sz >= min_spacing && sz < conf->hash_spacing) 238 conf->hash_spacing = sz; 239 } 240 241 mddev->queue->unplug_fn = raid0_unplug; 242 243 mddev->queue->issue_flush_fn = raid0_issue_flush; 244 245 printk("raid0: done.\n"); 246 return 0; 247 abort: 248 return 1; 249 } 250 251 /** 252 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged 253 * @q: request queue 254 * @bio: the buffer head that's been built up so far 255 * @biovec: the request that could be merged to it. 256 * 257 * Return amount of bytes we can accept at this offset 258 */ 259 static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec) 260 { 261 mddev_t *mddev = q->queuedata; 262 sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); 263 int max; 264 unsigned int chunk_sectors = mddev->chunk_size >> 9; 265 unsigned int bio_sectors = bio->bi_size >> 9; 266 267 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; 268 if (max < 0) max = 0; /* bio_add cannot handle a negative return */ 269 if (max <= biovec->bv_len && bio_sectors == 0) 270 return biovec->bv_len; 271 else 272 return max; 273 } 274 275 static int raid0_run (mddev_t *mddev) 276 { 277 unsigned cur=0, i=0, nb_zone; 278 s64 size; 279 raid0_conf_t *conf; 280 mdk_rdev_t *rdev; 281 struct list_head *tmp; 282 283 printk("%s: setting max_sectors to %d, segment boundary to %d\n", 284 mdname(mddev), 285 mddev->chunk_size >> 9, 286 (mddev->chunk_size>>1)-1); 287 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); 288 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); 289 290 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); 291 if (!conf) 292 goto out; 293 mddev->private = (void *)conf; 294 295 conf->strip_zone = NULL; 296 conf->devlist = NULL; 297 if (create_strip_zones (mddev)) 298 goto out_free_conf; 299 300 /* calculate array device size */ 301 mddev->array_size = 0; 302 ITERATE_RDEV(mddev,rdev,tmp) 303 mddev->array_size += rdev->size; 304 305 printk("raid0 : md_size is %llu blocks.\n", 306 (unsigned long long)mddev->array_size); 307 printk("raid0 : conf->hash_spacing is %llu blocks.\n", 308 (unsigned long long)conf->hash_spacing); 309 { 310 #if __GNUC__ < 3 311 volatile 312 #endif 313 sector_t s = mddev->array_size; 314 sector_t space = conf->hash_spacing; 315 int round; 316 conf->preshift = 0; 317 if (sizeof(sector_t) > sizeof(u32)) { 318 /*shift down space and s so that sector_div will work */ 319 while (space > (sector_t) (~(u32)0)) { 320 s >>= 1; 321 space >>= 1; 322 s += 1; /* force round-up */ 323 conf->preshift++; 324 } 325 } 326 round = sector_div(s, (u32)space) ? 1 : 0; 327 nb_zone = s + round; 328 } 329 printk("raid0 : nb_zone is %d.\n", nb_zone); 330 331 printk("raid0 : Allocating %Zd bytes for hash.\n", 332 nb_zone*sizeof(struct strip_zone*)); 333 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); 334 if (!conf->hash_table) 335 goto out_free_conf; 336 size = conf->strip_zone[cur].size; 337 338 for (i=0; i< nb_zone; i++) { 339 conf->hash_table[i] = conf->strip_zone + cur; 340 while (size <= conf->hash_spacing) { 341 cur++; 342 size += conf->strip_zone[cur].size; 343 } 344 size -= conf->hash_spacing; 345 } 346 if (conf->preshift) { 347 conf->hash_spacing >>= conf->preshift; 348 /* round hash_spacing up so when we divide by it, we 349 * err on the side of too-low, which is safest 350 */ 351 conf->hash_spacing++; 352 } 353 354 /* calculate the max read-ahead size. 355 * For read-ahead of large files to be effective, we need to 356 * readahead at least twice a whole stripe. i.e. number of devices 357 * multiplied by chunk size times 2. 358 * If an individual device has an ra_pages greater than the 359 * chunk size, then we will not drive that device as hard as it 360 * wants. We consider this a configuration error: a larger 361 * chunksize should be used in that case. 362 */ 363 { 364 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_CACHE_SIZE; 365 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 366 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 367 } 368 369 370 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 371 return 0; 372 373 out_free_conf: 374 kfree(conf->strip_zone); 375 kfree(conf->devlist); 376 kfree(conf); 377 mddev->private = NULL; 378 out: 379 return 1; 380 } 381 382 static int raid0_stop (mddev_t *mddev) 383 { 384 raid0_conf_t *conf = mddev_to_conf(mddev); 385 386 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 387 kfree(conf->hash_table); 388 conf->hash_table = NULL; 389 kfree(conf->strip_zone); 390 conf->strip_zone = NULL; 391 kfree(conf); 392 mddev->private = NULL; 393 394 return 0; 395 } 396 397 static int raid0_make_request (request_queue_t *q, struct bio *bio) 398 { 399 mddev_t *mddev = q->queuedata; 400 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects; 401 raid0_conf_t *conf = mddev_to_conf(mddev); 402 struct strip_zone *zone; 403 mdk_rdev_t *tmp_dev; 404 unsigned long chunk; 405 sector_t block, rsect; 406 const int rw = bio_data_dir(bio); 407 408 if (unlikely(bio_barrier(bio))) { 409 bio_endio(bio, bio->bi_size, -EOPNOTSUPP); 410 return 0; 411 } 412 413 disk_stat_inc(mddev->gendisk, ios[rw]); 414 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio)); 415 416 chunk_size = mddev->chunk_size >> 10; 417 chunk_sects = mddev->chunk_size >> 9; 418 chunksize_bits = ffz(~chunk_size); 419 block = bio->bi_sector >> 1; 420 421 422 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 423 struct bio_pair *bp; 424 /* Sanity check -- queue functions should prevent this happening */ 425 if (bio->bi_vcnt != 1 || 426 bio->bi_idx != 0) 427 goto bad_map; 428 /* This is a one page bio that upper layers 429 * refuse to split for us, so we need to split it. 430 */ 431 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) ); 432 if (raid0_make_request(q, &bp->bio1)) 433 generic_make_request(&bp->bio1); 434 if (raid0_make_request(q, &bp->bio2)) 435 generic_make_request(&bp->bio2); 436 437 bio_pair_release(bp); 438 return 0; 439 } 440 441 442 { 443 #if __GNUC__ < 3 444 volatile 445 #endif 446 sector_t x = block >> conf->preshift; 447 sector_div(x, (u32)conf->hash_spacing); 448 zone = conf->hash_table[x]; 449 } 450 451 while (block >= (zone->zone_offset + zone->size)) 452 zone++; 453 454 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1); 455 456 457 { 458 sector_t x = (block - zone->zone_offset) >> chunksize_bits; 459 460 sector_div(x, zone->nb_dev); 461 chunk = x; 462 BUG_ON(x != (sector_t)chunk); 463 464 x = block >> chunksize_bits; 465 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 466 } 467 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1) 468 + sect_in_chunk; 469 470 bio->bi_bdev = tmp_dev->bdev; 471 bio->bi_sector = rsect + tmp_dev->data_offset; 472 473 /* 474 * Let the main block layer submit the IO and resolve recursion: 475 */ 476 return 1; 477 478 bad_map: 479 printk("raid0_make_request bug: can't convert block across chunks" 480 " or bigger than %dk %llu %d\n", chunk_size, 481 (unsigned long long)bio->bi_sector, bio->bi_size >> 10); 482 483 bio_io_error(bio, bio->bi_size); 484 return 0; 485 } 486 487 static void raid0_status (struct seq_file *seq, mddev_t *mddev) 488 { 489 #undef MD_DEBUG 490 #ifdef MD_DEBUG 491 int j, k, h; 492 char b[BDEVNAME_SIZE]; 493 raid0_conf_t *conf = mddev_to_conf(mddev); 494 495 h = 0; 496 for (j = 0; j < conf->nr_strip_zones; j++) { 497 seq_printf(seq, " z%d", j); 498 if (conf->hash_table[h] == conf->strip_zone+j) 499 seq_printf("(h%d)", h++); 500 seq_printf(seq, "=["); 501 for (k = 0; k < conf->strip_zone[j].nb_dev; k++) 502 seq_printf (seq, "%s/", bdevname( 503 conf->strip_zone[j].dev[k]->bdev,b)); 504 505 seq_printf (seq, "] zo=%d do=%d s=%d\n", 506 conf->strip_zone[j].zone_offset, 507 conf->strip_zone[j].dev_offset, 508 conf->strip_zone[j].size); 509 } 510 #endif 511 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); 512 return; 513 } 514 515 static mdk_personality_t raid0_personality= 516 { 517 .name = "raid0", 518 .owner = THIS_MODULE, 519 .make_request = raid0_make_request, 520 .run = raid0_run, 521 .stop = raid0_stop, 522 .status = raid0_status, 523 }; 524 525 static int __init raid0_init (void) 526 { 527 return register_md_personality (RAID0, &raid0_personality); 528 } 529 530 static void raid0_exit (void) 531 { 532 unregister_md_personality (RAID0); 533 } 534 535 module_init(raid0_init); 536 module_exit(raid0_exit); 537 MODULE_LICENSE("GPL"); 538 MODULE_ALIAS("md-personality-2"); /* RAID0 */ 539