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/blkdev.h> 22 #include <linux/seq_file.h> 23 #include "md.h" 24 #include "raid0.h" 25 26 static void raid0_unplug(struct request_queue *q) 27 { 28 mddev_t *mddev = q->queuedata; 29 raid0_conf_t *conf = mddev_to_conf(mddev); 30 mdk_rdev_t **devlist = conf->strip_zone[0].dev; 31 int i; 32 33 for (i=0; i<mddev->raid_disks; i++) { 34 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev); 35 36 blk_unplug(r_queue); 37 } 38 } 39 40 static int raid0_congested(void *data, int bits) 41 { 42 mddev_t *mddev = data; 43 raid0_conf_t *conf = mddev_to_conf(mddev); 44 mdk_rdev_t **devlist = conf->strip_zone[0].dev; 45 int i, ret = 0; 46 47 for (i = 0; i < mddev->raid_disks && !ret ; i++) { 48 struct request_queue *q = bdev_get_queue(devlist[i]->bdev); 49 50 ret |= bdi_congested(&q->backing_dev_info, bits); 51 } 52 return ret; 53 } 54 55 56 static int create_strip_zones (mddev_t *mddev) 57 { 58 int i, c, j; 59 sector_t current_start, curr_zone_start; 60 sector_t min_spacing; 61 raid0_conf_t *conf = mddev_to_conf(mddev); 62 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev; 63 struct strip_zone *zone; 64 int cnt; 65 char b[BDEVNAME_SIZE]; 66 67 /* 68 * The number of 'same size groups' 69 */ 70 conf->nr_strip_zones = 0; 71 72 list_for_each_entry(rdev1, &mddev->disks, same_set) { 73 printk(KERN_INFO "raid0: looking at %s\n", 74 bdevname(rdev1->bdev,b)); 75 c = 0; 76 list_for_each_entry(rdev2, &mddev->disks, same_set) { 77 printk(KERN_INFO "raid0: comparing %s(%llu)", 78 bdevname(rdev1->bdev,b), 79 (unsigned long long)rdev1->sectors); 80 printk(KERN_INFO " with %s(%llu)\n", 81 bdevname(rdev2->bdev,b), 82 (unsigned long long)rdev2->sectors); 83 if (rdev2 == rdev1) { 84 printk(KERN_INFO "raid0: END\n"); 85 break; 86 } 87 if (rdev2->sectors == rdev1->sectors) { 88 /* 89 * Not unique, don't count it as a new 90 * group 91 */ 92 printk(KERN_INFO "raid0: EQUAL\n"); 93 c = 1; 94 break; 95 } 96 printk(KERN_INFO "raid0: NOT EQUAL\n"); 97 } 98 if (!c) { 99 printk(KERN_INFO "raid0: ==> UNIQUE\n"); 100 conf->nr_strip_zones++; 101 printk(KERN_INFO "raid0: %d zones\n", 102 conf->nr_strip_zones); 103 } 104 } 105 printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones); 106 107 conf->strip_zone = kzalloc(sizeof(struct strip_zone)* 108 conf->nr_strip_zones, GFP_KERNEL); 109 if (!conf->strip_zone) 110 return 1; 111 conf->devlist = kzalloc(sizeof(mdk_rdev_t*)* 112 conf->nr_strip_zones*mddev->raid_disks, 113 GFP_KERNEL); 114 if (!conf->devlist) 115 return 1; 116 117 /* The first zone must contain all devices, so here we check that 118 * there is a proper alignment of slots to devices and find them all 119 */ 120 zone = &conf->strip_zone[0]; 121 cnt = 0; 122 smallest = NULL; 123 zone->dev = conf->devlist; 124 list_for_each_entry(rdev1, &mddev->disks, same_set) { 125 int j = rdev1->raid_disk; 126 127 if (j < 0 || j >= mddev->raid_disks) { 128 printk(KERN_ERR "raid0: bad disk number %d - " 129 "aborting!\n", j); 130 goto abort; 131 } 132 if (zone->dev[j]) { 133 printk(KERN_ERR "raid0: multiple devices for %d - " 134 "aborting!\n", j); 135 goto abort; 136 } 137 zone->dev[j] = rdev1; 138 139 blk_queue_stack_limits(mddev->queue, 140 rdev1->bdev->bd_disk->queue); 141 /* as we don't honour merge_bvec_fn, we must never risk 142 * violating it, so limit ->max_sector to one PAGE, as 143 * a one page request is never in violation. 144 */ 145 146 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && 147 mddev->queue->max_sectors > (PAGE_SIZE>>9)) 148 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); 149 150 if (!smallest || (rdev1->sectors < smallest->sectors)) 151 smallest = rdev1; 152 cnt++; 153 } 154 if (cnt != mddev->raid_disks) { 155 printk(KERN_ERR "raid0: too few disks (%d of %d) - " 156 "aborting!\n", cnt, mddev->raid_disks); 157 goto abort; 158 } 159 zone->nb_dev = cnt; 160 zone->sectors = smallest->sectors * cnt; 161 zone->zone_start = 0; 162 163 current_start = smallest->sectors; 164 curr_zone_start = zone->sectors; 165 166 /* now do the other zones */ 167 for (i = 1; i < conf->nr_strip_zones; i++) 168 { 169 zone = conf->strip_zone + i; 170 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks; 171 172 printk(KERN_INFO "raid0: zone %d\n", i); 173 zone->dev_start = current_start; 174 smallest = NULL; 175 c = 0; 176 177 for (j=0; j<cnt; j++) { 178 char b[BDEVNAME_SIZE]; 179 rdev = conf->strip_zone[0].dev[j]; 180 printk(KERN_INFO "raid0: checking %s ...", 181 bdevname(rdev->bdev, b)); 182 if (rdev->sectors <= current_start) { 183 printk(KERN_INFO " nope.\n"); 184 continue; 185 } 186 printk(KERN_INFO " contained as device %d\n", c); 187 zone->dev[c] = rdev; 188 c++; 189 if (!smallest || rdev->sectors < smallest->sectors) { 190 smallest = rdev; 191 printk(KERN_INFO " (%llu) is smallest!.\n", 192 (unsigned long long)rdev->sectors); 193 } 194 } 195 196 zone->nb_dev = c; 197 zone->sectors = (smallest->sectors - current_start) * c; 198 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n", 199 zone->nb_dev, (unsigned long long)zone->sectors); 200 201 zone->zone_start = curr_zone_start; 202 curr_zone_start += zone->sectors; 203 204 current_start = smallest->sectors; 205 printk(KERN_INFO "raid0: current zone start: %llu\n", 206 (unsigned long long)current_start); 207 } 208 209 /* Now find appropriate hash spacing. 210 * We want a number which causes most hash entries to cover 211 * at most two strips, but the hash table must be at most 212 * 1 PAGE. We choose the smallest strip, or contiguous collection 213 * of strips, that has big enough size. We never consider the last 214 * strip though as it's size has no bearing on the efficacy of the hash 215 * table. 216 */ 217 conf->spacing = curr_zone_start; 218 min_spacing = curr_zone_start; 219 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*)); 220 for (i=0; i < conf->nr_strip_zones-1; i++) { 221 sector_t s = 0; 222 for (j = i; j < conf->nr_strip_zones - 1 && 223 s < min_spacing; j++) 224 s += conf->strip_zone[j].sectors; 225 if (s >= min_spacing && s < conf->spacing) 226 conf->spacing = s; 227 } 228 229 mddev->queue->unplug_fn = raid0_unplug; 230 231 mddev->queue->backing_dev_info.congested_fn = raid0_congested; 232 mddev->queue->backing_dev_info.congested_data = mddev; 233 234 printk(KERN_INFO "raid0: done.\n"); 235 return 0; 236 abort: 237 return 1; 238 } 239 240 /** 241 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged 242 * @q: request queue 243 * @bvm: properties of new bio 244 * @biovec: the request that could be merged to it. 245 * 246 * Return amount of bytes we can accept at this offset 247 */ 248 static int raid0_mergeable_bvec(struct request_queue *q, 249 struct bvec_merge_data *bvm, 250 struct bio_vec *biovec) 251 { 252 mddev_t *mddev = q->queuedata; 253 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); 254 int max; 255 unsigned int chunk_sectors = mddev->chunk_size >> 9; 256 unsigned int bio_sectors = bvm->bi_size >> 9; 257 258 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; 259 if (max < 0) max = 0; /* bio_add cannot handle a negative return */ 260 if (max <= biovec->bv_len && bio_sectors == 0) 261 return biovec->bv_len; 262 else 263 return max; 264 } 265 266 static sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks) 267 { 268 sector_t array_sectors = 0; 269 mdk_rdev_t *rdev; 270 271 WARN_ONCE(sectors || raid_disks, 272 "%s does not support generic reshape\n", __func__); 273 274 list_for_each_entry(rdev, &mddev->disks, same_set) 275 array_sectors += rdev->sectors; 276 277 return array_sectors; 278 } 279 280 static int raid0_run (mddev_t *mddev) 281 { 282 unsigned cur=0, i=0, nb_zone; 283 s64 sectors; 284 raid0_conf_t *conf; 285 286 if (mddev->chunk_size == 0) { 287 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n"); 288 return -EINVAL; 289 } 290 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n", 291 mdname(mddev), 292 mddev->chunk_size >> 9, 293 (mddev->chunk_size>>1)-1); 294 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); 295 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); 296 mddev->queue->queue_lock = &mddev->queue->__queue_lock; 297 298 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); 299 if (!conf) 300 goto out; 301 mddev->private = (void *)conf; 302 303 conf->strip_zone = NULL; 304 conf->devlist = NULL; 305 if (create_strip_zones (mddev)) 306 goto out_free_conf; 307 308 /* calculate array device size */ 309 md_set_array_sectors(mddev, raid0_size(mddev, 0, 0)); 310 311 printk(KERN_INFO "raid0 : md_size is %llu sectors.\n", 312 (unsigned long long)mddev->array_sectors); 313 printk(KERN_INFO "raid0 : conf->spacing is %llu sectors.\n", 314 (unsigned long long)conf->spacing); 315 { 316 sector_t s = raid0_size(mddev, 0, 0); 317 sector_t space = conf->spacing; 318 int round; 319 conf->sector_shift = 0; 320 if (sizeof(sector_t) > sizeof(u32)) { 321 /*shift down space and s so that sector_div will work */ 322 while (space > (sector_t) (~(u32)0)) { 323 s >>= 1; 324 space >>= 1; 325 s += 1; /* force round-up */ 326 conf->sector_shift++; 327 } 328 } 329 round = sector_div(s, (u32)space) ? 1 : 0; 330 nb_zone = s + round; 331 } 332 printk(KERN_INFO "raid0 : nb_zone is %d.\n", nb_zone); 333 334 printk(KERN_INFO "raid0 : Allocating %zu bytes for hash.\n", 335 nb_zone*sizeof(struct strip_zone*)); 336 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); 337 if (!conf->hash_table) 338 goto out_free_conf; 339 sectors = conf->strip_zone[cur].sectors; 340 341 conf->hash_table[0] = conf->strip_zone + cur; 342 for (i=1; i< nb_zone; i++) { 343 while (sectors <= conf->spacing) { 344 cur++; 345 sectors += conf->strip_zone[cur].sectors; 346 } 347 sectors -= conf->spacing; 348 conf->hash_table[i] = conf->strip_zone + cur; 349 } 350 if (conf->sector_shift) { 351 conf->spacing >>= conf->sector_shift; 352 /* round spacing up so when we divide by it, we 353 * err on the side of too-low, which is safest 354 */ 355 conf->spacing++; 356 } 357 358 /* calculate the max read-ahead size. 359 * For read-ahead of large files to be effective, we need to 360 * readahead at least twice a whole stripe. i.e. number of devices 361 * multiplied by chunk size times 2. 362 * If an individual device has an ra_pages greater than the 363 * chunk size, then we will not drive that device as hard as it 364 * wants. We consider this a configuration error: a larger 365 * chunksize should be used in that case. 366 */ 367 { 368 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE; 369 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 370 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 371 } 372 373 374 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 375 return 0; 376 377 out_free_conf: 378 kfree(conf->strip_zone); 379 kfree(conf->devlist); 380 kfree(conf); 381 mddev->private = NULL; 382 out: 383 return -ENOMEM; 384 } 385 386 static int raid0_stop (mddev_t *mddev) 387 { 388 raid0_conf_t *conf = mddev_to_conf(mddev); 389 390 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 391 kfree(conf->hash_table); 392 conf->hash_table = NULL; 393 kfree(conf->strip_zone); 394 conf->strip_zone = NULL; 395 kfree(conf); 396 mddev->private = NULL; 397 398 return 0; 399 } 400 401 static int raid0_make_request (struct request_queue *q, struct bio *bio) 402 { 403 mddev_t *mddev = q->queuedata; 404 unsigned int sect_in_chunk, chunksect_bits, chunk_sects; 405 raid0_conf_t *conf = mddev_to_conf(mddev); 406 struct strip_zone *zone; 407 mdk_rdev_t *tmp_dev; 408 sector_t chunk; 409 sector_t sector, rsect; 410 const int rw = bio_data_dir(bio); 411 int cpu; 412 413 if (unlikely(bio_barrier(bio))) { 414 bio_endio(bio, -EOPNOTSUPP); 415 return 0; 416 } 417 418 cpu = part_stat_lock(); 419 part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); 420 part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], 421 bio_sectors(bio)); 422 part_stat_unlock(); 423 424 chunk_sects = mddev->chunk_size >> 9; 425 chunksect_bits = ffz(~chunk_sects); 426 sector = bio->bi_sector; 427 428 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 429 struct bio_pair *bp; 430 /* Sanity check -- queue functions should prevent this happening */ 431 if (bio->bi_vcnt != 1 || 432 bio->bi_idx != 0) 433 goto bad_map; 434 /* This is a one page bio that upper layers 435 * refuse to split for us, so we need to split it. 436 */ 437 bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1))); 438 if (raid0_make_request(q, &bp->bio1)) 439 generic_make_request(&bp->bio1); 440 if (raid0_make_request(q, &bp->bio2)) 441 generic_make_request(&bp->bio2); 442 443 bio_pair_release(bp); 444 return 0; 445 } 446 447 448 { 449 sector_t x = sector >> conf->sector_shift; 450 sector_div(x, (u32)conf->spacing); 451 zone = conf->hash_table[x]; 452 } 453 454 while (sector >= zone->zone_start + zone->sectors) 455 zone++; 456 457 sect_in_chunk = bio->bi_sector & (chunk_sects - 1); 458 459 460 { 461 sector_t x = (sector - zone->zone_start) >> chunksect_bits; 462 463 sector_div(x, zone->nb_dev); 464 chunk = x; 465 466 x = sector >> chunksect_bits; 467 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 468 } 469 rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk; 470 471 bio->bi_bdev = tmp_dev->bdev; 472 bio->bi_sector = rsect + tmp_dev->data_offset; 473 474 /* 475 * Let the main block layer submit the IO and resolve recursion: 476 */ 477 return 1; 478 479 bad_map: 480 printk("raid0_make_request bug: can't convert block across chunks" 481 " or bigger than %dk %llu %d\n", chunk_sects / 2, 482 (unsigned long long)bio->bi_sector, bio->bi_size >> 10); 483 484 bio_io_error(bio); 485 return 0; 486 } 487 488 static void raid0_status (struct seq_file *seq, mddev_t *mddev) 489 { 490 #undef MD_DEBUG 491 #ifdef MD_DEBUG 492 int j, k, h; 493 char b[BDEVNAME_SIZE]; 494 raid0_conf_t *conf = mddev_to_conf(mddev); 495 496 h = 0; 497 for (j = 0; j < conf->nr_strip_zones; j++) { 498 seq_printf(seq, " z%d", j); 499 if (conf->hash_table[h] == conf->strip_zone+j) 500 seq_printf(seq, "(h%d)", h++); 501 seq_printf(seq, "=["); 502 for (k = 0; k < conf->strip_zone[j].nb_dev; k++) 503 seq_printf(seq, "%s/", bdevname( 504 conf->strip_zone[j].dev[k]->bdev,b)); 505 506 seq_printf(seq, "] zs=%d ds=%d s=%d\n", 507 conf->strip_zone[j].zone_start, 508 conf->strip_zone[j].dev_start, 509 conf->strip_zone[j].sectors); 510 } 511 #endif 512 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); 513 return; 514 } 515 516 static struct mdk_personality raid0_personality= 517 { 518 .name = "raid0", 519 .level = 0, 520 .owner = THIS_MODULE, 521 .make_request = raid0_make_request, 522 .run = raid0_run, 523 .stop = raid0_stop, 524 .status = raid0_status, 525 .size = raid0_size, 526 }; 527 528 static int __init raid0_init (void) 529 { 530 return register_md_personality (&raid0_personality); 531 } 532 533 static void raid0_exit (void) 534 { 535 unregister_md_personality (&raid0_personality); 536 } 537 538 module_init(raid0_init); 539 module_exit(raid0_exit); 540 MODULE_LICENSE("GPL"); 541 MODULE_ALIAS("md-personality-2"); /* RAID0 */ 542 MODULE_ALIAS("md-raid0"); 543 MODULE_ALIAS("md-level-0"); 544