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/raid/raid0.h> 22 23 static void raid0_unplug(struct request_queue *q) 24 { 25 mddev_t *mddev = q->queuedata; 26 raid0_conf_t *conf = mddev_to_conf(mddev); 27 mdk_rdev_t **devlist = conf->strip_zone[0].dev; 28 int i; 29 30 for (i=0; i<mddev->raid_disks; i++) { 31 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev); 32 33 blk_unplug(r_queue); 34 } 35 } 36 37 static int raid0_congested(void *data, int bits) 38 { 39 mddev_t *mddev = data; 40 raid0_conf_t *conf = mddev_to_conf(mddev); 41 mdk_rdev_t **devlist = conf->strip_zone[0].dev; 42 int i, ret = 0; 43 44 for (i = 0; i < mddev->raid_disks && !ret ; i++) { 45 struct request_queue *q = bdev_get_queue(devlist[i]->bdev); 46 47 ret |= bdi_congested(&q->backing_dev_info, bits); 48 } 49 return ret; 50 } 51 52 53 static int create_strip_zones (mddev_t *mddev) 54 { 55 int i, c, j; 56 sector_t current_start, curr_zone_start; 57 sector_t min_spacing; 58 raid0_conf_t *conf = mddev_to_conf(mddev); 59 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev; 60 struct strip_zone *zone; 61 int cnt; 62 char b[BDEVNAME_SIZE]; 63 64 /* 65 * The number of 'same size groups' 66 */ 67 conf->nr_strip_zones = 0; 68 69 list_for_each_entry(rdev1, &mddev->disks, same_set) { 70 printk(KERN_INFO "raid0: looking at %s\n", 71 bdevname(rdev1->bdev,b)); 72 c = 0; 73 list_for_each_entry(rdev2, &mddev->disks, same_set) { 74 printk(KERN_INFO "raid0: comparing %s(%llu)", 75 bdevname(rdev1->bdev,b), 76 (unsigned long long)rdev1->size); 77 printk(KERN_INFO " with %s(%llu)\n", 78 bdevname(rdev2->bdev,b), 79 (unsigned long long)rdev2->size); 80 if (rdev2 == rdev1) { 81 printk(KERN_INFO "raid0: END\n"); 82 break; 83 } 84 if (rdev2->size == rdev1->size) 85 { 86 /* 87 * Not unique, don't count it as a new 88 * group 89 */ 90 printk(KERN_INFO "raid0: EQUAL\n"); 91 c = 1; 92 break; 93 } 94 printk(KERN_INFO "raid0: NOT EQUAL\n"); 95 } 96 if (!c) { 97 printk(KERN_INFO "raid0: ==> UNIQUE\n"); 98 conf->nr_strip_zones++; 99 printk(KERN_INFO "raid0: %d zones\n", 100 conf->nr_strip_zones); 101 } 102 } 103 printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones); 104 105 conf->strip_zone = kzalloc(sizeof(struct strip_zone)* 106 conf->nr_strip_zones, GFP_KERNEL); 107 if (!conf->strip_zone) 108 return 1; 109 conf->devlist = kzalloc(sizeof(mdk_rdev_t*)* 110 conf->nr_strip_zones*mddev->raid_disks, 111 GFP_KERNEL); 112 if (!conf->devlist) 113 return 1; 114 115 /* The first zone must contain all devices, so here we check that 116 * there is a proper alignment of slots to devices and find them all 117 */ 118 zone = &conf->strip_zone[0]; 119 cnt = 0; 120 smallest = NULL; 121 zone->dev = conf->devlist; 122 list_for_each_entry(rdev1, &mddev->disks, same_set) { 123 int j = rdev1->raid_disk; 124 125 if (j < 0 || j >= mddev->raid_disks) { 126 printk(KERN_ERR "raid0: bad disk number %d - " 127 "aborting!\n", j); 128 goto abort; 129 } 130 if (zone->dev[j]) { 131 printk(KERN_ERR "raid0: multiple devices for %d - " 132 "aborting!\n", j); 133 goto abort; 134 } 135 zone->dev[j] = rdev1; 136 137 blk_queue_stack_limits(mddev->queue, 138 rdev1->bdev->bd_disk->queue); 139 /* as we don't honour merge_bvec_fn, we must never risk 140 * violating it, so limit ->max_sector to one PAGE, as 141 * a one page request is never in violation. 142 */ 143 144 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && 145 mddev->queue->max_sectors > (PAGE_SIZE>>9)) 146 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); 147 148 if (!smallest || (rdev1->size <smallest->size)) 149 smallest = rdev1; 150 cnt++; 151 } 152 if (cnt != mddev->raid_disks) { 153 printk(KERN_ERR "raid0: too few disks (%d of %d) - " 154 "aborting!\n", cnt, mddev->raid_disks); 155 goto abort; 156 } 157 zone->nb_dev = cnt; 158 zone->sectors = smallest->size * cnt * 2; 159 zone->zone_start = 0; 160 161 current_start = smallest->size * 2; 162 curr_zone_start = zone->sectors; 163 164 /* now do the other zones */ 165 for (i = 1; i < conf->nr_strip_zones; i++) 166 { 167 zone = conf->strip_zone + i; 168 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks; 169 170 printk(KERN_INFO "raid0: zone %d\n", i); 171 zone->dev_start = current_start; 172 smallest = NULL; 173 c = 0; 174 175 for (j=0; j<cnt; j++) { 176 char b[BDEVNAME_SIZE]; 177 rdev = conf->strip_zone[0].dev[j]; 178 printk(KERN_INFO "raid0: checking %s ...", 179 bdevname(rdev->bdev, b)); 180 if (rdev->size > current_start / 2) { 181 printk(KERN_INFO " contained as device %d\n", 182 c); 183 zone->dev[c] = rdev; 184 c++; 185 if (!smallest || (rdev->size <smallest->size)) { 186 smallest = rdev; 187 printk(KERN_INFO " (%llu) is smallest!.\n", 188 (unsigned long long)rdev->size); 189 } 190 } else 191 printk(KERN_INFO " nope.\n"); 192 } 193 194 zone->nb_dev = c; 195 zone->sectors = (smallest->size * 2 - current_start) * c; 196 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n", 197 zone->nb_dev, (unsigned long long)zone->sectors); 198 199 zone->zone_start = curr_zone_start; 200 curr_zone_start += zone->sectors; 201 202 current_start = smallest->size * 2; 203 printk(KERN_INFO "raid0: current zone start: %llu\n", 204 (unsigned long long)current_start); 205 } 206 207 /* Now find appropriate hash spacing. 208 * We want a number which causes most hash entries to cover 209 * at most two strips, but the hash table must be at most 210 * 1 PAGE. We choose the smallest strip, or contiguous collection 211 * of strips, that has big enough size. We never consider the last 212 * strip though as it's size has no bearing on the efficacy of the hash 213 * table. 214 */ 215 conf->spacing = curr_zone_start; 216 min_spacing = curr_zone_start; 217 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*)); 218 for (i=0; i < conf->nr_strip_zones-1; i++) { 219 sector_t s = 0; 220 for (j = i; j < conf->nr_strip_zones - 1 && 221 s < min_spacing; j++) 222 s += conf->strip_zone[j].sectors; 223 if (s >= min_spacing && s < conf->spacing) 224 conf->spacing = s; 225 } 226 227 mddev->queue->unplug_fn = raid0_unplug; 228 229 mddev->queue->backing_dev_info.congested_fn = raid0_congested; 230 mddev->queue->backing_dev_info.congested_data = mddev; 231 232 printk(KERN_INFO "raid0: done.\n"); 233 return 0; 234 abort: 235 return 1; 236 } 237 238 /** 239 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged 240 * @q: request queue 241 * @bvm: properties of new bio 242 * @biovec: the request that could be merged to it. 243 * 244 * Return amount of bytes we can accept at this offset 245 */ 246 static int raid0_mergeable_bvec(struct request_queue *q, 247 struct bvec_merge_data *bvm, 248 struct bio_vec *biovec) 249 { 250 mddev_t *mddev = q->queuedata; 251 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); 252 int max; 253 unsigned int chunk_sectors = mddev->chunk_size >> 9; 254 unsigned int bio_sectors = bvm->bi_size >> 9; 255 256 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; 257 if (max < 0) max = 0; /* bio_add cannot handle a negative return */ 258 if (max <= biovec->bv_len && bio_sectors == 0) 259 return biovec->bv_len; 260 else 261 return max; 262 } 263 264 static int raid0_run (mddev_t *mddev) 265 { 266 unsigned cur=0, i=0, nb_zone; 267 s64 sectors; 268 raid0_conf_t *conf; 269 mdk_rdev_t *rdev; 270 271 if (mddev->chunk_size == 0) { 272 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n"); 273 return -EINVAL; 274 } 275 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n", 276 mdname(mddev), 277 mddev->chunk_size >> 9, 278 (mddev->chunk_size>>1)-1); 279 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); 280 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); 281 mddev->queue->queue_lock = &mddev->queue->__queue_lock; 282 283 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); 284 if (!conf) 285 goto out; 286 mddev->private = (void *)conf; 287 288 conf->strip_zone = NULL; 289 conf->devlist = NULL; 290 if (create_strip_zones (mddev)) 291 goto out_free_conf; 292 293 /* calculate array device size */ 294 mddev->array_sectors = 0; 295 list_for_each_entry(rdev, &mddev->disks, same_set) 296 mddev->array_sectors += rdev->size * 2; 297 298 printk(KERN_INFO "raid0 : md_size is %llu sectors.\n", 299 (unsigned long long)mddev->array_sectors); 300 printk(KERN_INFO "raid0 : conf->spacing is %llu sectors.\n", 301 (unsigned long long)conf->spacing); 302 { 303 sector_t s = mddev->array_sectors; 304 sector_t space = conf->spacing; 305 int round; 306 conf->sector_shift = 0; 307 if (sizeof(sector_t) > sizeof(u32)) { 308 /*shift down space and s so that sector_div will work */ 309 while (space > (sector_t) (~(u32)0)) { 310 s >>= 1; 311 space >>= 1; 312 s += 1; /* force round-up */ 313 conf->sector_shift++; 314 } 315 } 316 round = sector_div(s, (u32)space) ? 1 : 0; 317 nb_zone = s + round; 318 } 319 printk(KERN_INFO "raid0 : nb_zone is %d.\n", nb_zone); 320 321 printk(KERN_INFO "raid0 : Allocating %zu bytes for hash.\n", 322 nb_zone*sizeof(struct strip_zone*)); 323 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); 324 if (!conf->hash_table) 325 goto out_free_conf; 326 sectors = conf->strip_zone[cur].sectors; 327 328 conf->hash_table[0] = conf->strip_zone + cur; 329 for (i=1; i< nb_zone; i++) { 330 while (sectors <= conf->spacing) { 331 cur++; 332 sectors += conf->strip_zone[cur].sectors; 333 } 334 sectors -= conf->spacing; 335 conf->hash_table[i] = conf->strip_zone + cur; 336 } 337 if (conf->sector_shift) { 338 conf->spacing >>= conf->sector_shift; 339 /* round spacing up so when we divide by it, we 340 * err on the side of too-low, which is safest 341 */ 342 conf->spacing++; 343 } 344 345 /* calculate the max read-ahead size. 346 * For read-ahead of large files to be effective, we need to 347 * readahead at least twice a whole stripe. i.e. number of devices 348 * multiplied by chunk size times 2. 349 * If an individual device has an ra_pages greater than the 350 * chunk size, then we will not drive that device as hard as it 351 * wants. We consider this a configuration error: a larger 352 * chunksize should be used in that case. 353 */ 354 { 355 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE; 356 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 357 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 358 } 359 360 361 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 362 return 0; 363 364 out_free_conf: 365 kfree(conf->strip_zone); 366 kfree(conf->devlist); 367 kfree(conf); 368 mddev->private = NULL; 369 out: 370 return -ENOMEM; 371 } 372 373 static int raid0_stop (mddev_t *mddev) 374 { 375 raid0_conf_t *conf = mddev_to_conf(mddev); 376 377 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 378 kfree(conf->hash_table); 379 conf->hash_table = NULL; 380 kfree(conf->strip_zone); 381 conf->strip_zone = NULL; 382 kfree(conf); 383 mddev->private = NULL; 384 385 return 0; 386 } 387 388 static int raid0_make_request (struct request_queue *q, struct bio *bio) 389 { 390 mddev_t *mddev = q->queuedata; 391 unsigned int sect_in_chunk, chunksect_bits, chunk_sects; 392 raid0_conf_t *conf = mddev_to_conf(mddev); 393 struct strip_zone *zone; 394 mdk_rdev_t *tmp_dev; 395 sector_t chunk; 396 sector_t sector, rsect; 397 const int rw = bio_data_dir(bio); 398 int cpu; 399 400 if (unlikely(bio_barrier(bio))) { 401 bio_endio(bio, -EOPNOTSUPP); 402 return 0; 403 } 404 405 cpu = part_stat_lock(); 406 part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); 407 part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], 408 bio_sectors(bio)); 409 part_stat_unlock(); 410 411 chunk_sects = mddev->chunk_size >> 9; 412 chunksect_bits = ffz(~chunk_sects); 413 sector = bio->bi_sector; 414 415 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 416 struct bio_pair *bp; 417 /* Sanity check -- queue functions should prevent this happening */ 418 if (bio->bi_vcnt != 1 || 419 bio->bi_idx != 0) 420 goto bad_map; 421 /* This is a one page bio that upper layers 422 * refuse to split for us, so we need to split it. 423 */ 424 bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1))); 425 if (raid0_make_request(q, &bp->bio1)) 426 generic_make_request(&bp->bio1); 427 if (raid0_make_request(q, &bp->bio2)) 428 generic_make_request(&bp->bio2); 429 430 bio_pair_release(bp); 431 return 0; 432 } 433 434 435 { 436 sector_t x = sector >> conf->sector_shift; 437 sector_div(x, (u32)conf->spacing); 438 zone = conf->hash_table[x]; 439 } 440 441 while (sector >= zone->zone_start + zone->sectors) 442 zone++; 443 444 sect_in_chunk = bio->bi_sector & (chunk_sects - 1); 445 446 447 { 448 sector_t x = (sector - zone->zone_start) >> chunksect_bits; 449 450 sector_div(x, zone->nb_dev); 451 chunk = x; 452 453 x = sector >> chunksect_bits; 454 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 455 } 456 rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk; 457 458 bio->bi_bdev = tmp_dev->bdev; 459 bio->bi_sector = rsect + tmp_dev->data_offset; 460 461 /* 462 * Let the main block layer submit the IO and resolve recursion: 463 */ 464 return 1; 465 466 bad_map: 467 printk("raid0_make_request bug: can't convert block across chunks" 468 " or bigger than %dk %llu %d\n", chunk_sects / 2, 469 (unsigned long long)bio->bi_sector, bio->bi_size >> 10); 470 471 bio_io_error(bio); 472 return 0; 473 } 474 475 static void raid0_status (struct seq_file *seq, mddev_t *mddev) 476 { 477 #undef MD_DEBUG 478 #ifdef MD_DEBUG 479 int j, k, h; 480 char b[BDEVNAME_SIZE]; 481 raid0_conf_t *conf = mddev_to_conf(mddev); 482 483 h = 0; 484 for (j = 0; j < conf->nr_strip_zones; j++) { 485 seq_printf(seq, " z%d", j); 486 if (conf->hash_table[h] == conf->strip_zone+j) 487 seq_printf(seq, "(h%d)", h++); 488 seq_printf(seq, "=["); 489 for (k = 0; k < conf->strip_zone[j].nb_dev; k++) 490 seq_printf(seq, "%s/", bdevname( 491 conf->strip_zone[j].dev[k]->bdev,b)); 492 493 seq_printf(seq, "] zs=%d ds=%d s=%d\n", 494 conf->strip_zone[j].zone_start, 495 conf->strip_zone[j].dev_start, 496 conf->strip_zone[j].sectors); 497 } 498 #endif 499 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); 500 return; 501 } 502 503 static struct mdk_personality raid0_personality= 504 { 505 .name = "raid0", 506 .level = 0, 507 .owner = THIS_MODULE, 508 .make_request = raid0_make_request, 509 .run = raid0_run, 510 .stop = raid0_stop, 511 .status = raid0_status, 512 }; 513 514 static int __init raid0_init (void) 515 { 516 return register_md_personality (&raid0_personality); 517 } 518 519 static void raid0_exit (void) 520 { 521 unregister_md_personality (&raid0_personality); 522 } 523 524 module_init(raid0_init); 525 module_exit(raid0_exit); 526 MODULE_LICENSE("GPL"); 527 MODULE_ALIAS("md-personality-2"); /* RAID0 */ 528 MODULE_ALIAS("md-raid0"); 529 MODULE_ALIAS("md-level-0"); 530