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(struct request_queue *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 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev); 37 38 blk_unplug(r_queue); 39 } 40 } 41 42 static int raid0_congested(void *data, int bits) 43 { 44 mddev_t *mddev = data; 45 raid0_conf_t *conf = mddev_to_conf(mddev); 46 mdk_rdev_t **devlist = conf->strip_zone[0].dev; 47 int i, ret = 0; 48 49 for (i = 0; i < mddev->raid_disks && !ret ; i++) { 50 struct request_queue *q = bdev_get_queue(devlist[i]->bdev); 51 52 ret |= bdi_congested(&q->backing_dev_info, bits); 53 } 54 return ret; 55 } 56 57 58 static int create_strip_zones (mddev_t *mddev) 59 { 60 int i, c, j; 61 sector_t current_offset, curr_zone_offset; 62 sector_t min_spacing; 63 raid0_conf_t *conf = mddev_to_conf(mddev); 64 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev; 65 struct list_head *tmp1, *tmp2; 66 struct strip_zone *zone; 67 int cnt; 68 char b[BDEVNAME_SIZE]; 69 70 /* 71 * The number of 'same size groups' 72 */ 73 conf->nr_strip_zones = 0; 74 75 rdev_for_each(rdev1, tmp1, mddev) { 76 printk("raid0: looking at %s\n", 77 bdevname(rdev1->bdev,b)); 78 c = 0; 79 rdev_for_each(rdev2, tmp2, mddev) { 80 printk("raid0: comparing %s(%llu)", 81 bdevname(rdev1->bdev,b), 82 (unsigned long long)rdev1->size); 83 printk(" with %s(%llu)\n", 84 bdevname(rdev2->bdev,b), 85 (unsigned long long)rdev2->size); 86 if (rdev2 == rdev1) { 87 printk("raid0: END\n"); 88 break; 89 } 90 if (rdev2->size == rdev1->size) 91 { 92 /* 93 * Not unique, don't count it as a new 94 * group 95 */ 96 printk("raid0: EQUAL\n"); 97 c = 1; 98 break; 99 } 100 printk("raid0: NOT EQUAL\n"); 101 } 102 if (!c) { 103 printk("raid0: ==> UNIQUE\n"); 104 conf->nr_strip_zones++; 105 printk("raid0: %d zones\n", conf->nr_strip_zones); 106 } 107 } 108 printk("raid0: FINAL %d zones\n", conf->nr_strip_zones); 109 110 conf->strip_zone = kzalloc(sizeof(struct strip_zone)* 111 conf->nr_strip_zones, GFP_KERNEL); 112 if (!conf->strip_zone) 113 return 1; 114 conf->devlist = kzalloc(sizeof(mdk_rdev_t*)* 115 conf->nr_strip_zones*mddev->raid_disks, 116 GFP_KERNEL); 117 if (!conf->devlist) 118 return 1; 119 120 /* The first zone must contain all devices, so here we check that 121 * there is a proper alignment of slots to devices and find them all 122 */ 123 zone = &conf->strip_zone[0]; 124 cnt = 0; 125 smallest = NULL; 126 zone->dev = conf->devlist; 127 rdev_for_each(rdev1, tmp1, mddev) { 128 int j = rdev1->raid_disk; 129 130 if (j < 0 || j >= mddev->raid_disks) { 131 printk("raid0: bad disk number %d - aborting!\n", j); 132 goto abort; 133 } 134 if (zone->dev[j]) { 135 printk("raid0: multiple devices for %d - aborting!\n", 136 j); 137 goto abort; 138 } 139 zone->dev[j] = rdev1; 140 141 blk_queue_stack_limits(mddev->queue, 142 rdev1->bdev->bd_disk->queue); 143 /* as we don't honour merge_bvec_fn, we must never risk 144 * violating it, so limit ->max_sector to one PAGE, as 145 * a one page request is never in violation. 146 */ 147 148 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && 149 mddev->queue->max_sectors > (PAGE_SIZE>>9)) 150 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); 151 152 if (!smallest || (rdev1->size <smallest->size)) 153 smallest = rdev1; 154 cnt++; 155 } 156 if (cnt != mddev->raid_disks) { 157 printk("raid0: too few disks (%d of %d) - aborting!\n", 158 cnt, mddev->raid_disks); 159 goto abort; 160 } 161 zone->nb_dev = cnt; 162 zone->size = smallest->size * cnt; 163 zone->zone_offset = 0; 164 165 current_offset = smallest->size; 166 curr_zone_offset = zone->size; 167 168 /* now do the other zones */ 169 for (i = 1; i < conf->nr_strip_zones; i++) 170 { 171 zone = conf->strip_zone + i; 172 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks; 173 174 printk("raid0: zone %d\n", i); 175 zone->dev_offset = current_offset; 176 smallest = NULL; 177 c = 0; 178 179 for (j=0; j<cnt; j++) { 180 char b[BDEVNAME_SIZE]; 181 rdev = conf->strip_zone[0].dev[j]; 182 printk("raid0: checking %s ...", bdevname(rdev->bdev,b)); 183 if (rdev->size > current_offset) 184 { 185 printk(" contained as device %d\n", c); 186 zone->dev[c] = rdev; 187 c++; 188 if (!smallest || (rdev->size <smallest->size)) { 189 smallest = rdev; 190 printk(" (%llu) is smallest!.\n", 191 (unsigned long long)rdev->size); 192 } 193 } else 194 printk(" nope.\n"); 195 } 196 197 zone->nb_dev = c; 198 zone->size = (smallest->size - current_offset) * c; 199 printk("raid0: zone->nb_dev: %d, size: %llu\n", 200 zone->nb_dev, (unsigned long long)zone->size); 201 202 zone->zone_offset = curr_zone_offset; 203 curr_zone_offset += zone->size; 204 205 current_offset = smallest->size; 206 printk("raid0: current zone offset: %llu\n", 207 (unsigned long long)current_offset); 208 } 209 210 /* Now find appropriate hash spacing. 211 * We want a number which causes most hash entries to cover 212 * at most two strips, but the hash table must be at most 213 * 1 PAGE. We choose the smallest strip, or contiguous collection 214 * of strips, that has big enough size. We never consider the last 215 * strip though as it's size has no bearing on the efficacy of the hash 216 * table. 217 */ 218 conf->hash_spacing = curr_zone_offset; 219 min_spacing = curr_zone_offset; 220 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*)); 221 for (i=0; i < conf->nr_strip_zones-1; i++) { 222 sector_t sz = 0; 223 for (j=i; j<conf->nr_strip_zones-1 && 224 sz < min_spacing ; j++) 225 sz += conf->strip_zone[j].size; 226 if (sz >= min_spacing && sz < conf->hash_spacing) 227 conf->hash_spacing = sz; 228 } 229 230 mddev->queue->unplug_fn = raid0_unplug; 231 232 mddev->queue->backing_dev_info.congested_fn = raid0_congested; 233 mddev->queue->backing_dev_info.congested_data = mddev; 234 235 printk("raid0: done.\n"); 236 return 0; 237 abort: 238 return 1; 239 } 240 241 /** 242 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged 243 * @q: request queue 244 * @bio: the buffer head that's been built up so far 245 * @biovec: the request that could be merged to it. 246 * 247 * Return amount of bytes we can accept at this offset 248 */ 249 static int raid0_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec) 250 { 251 mddev_t *mddev = q->queuedata; 252 sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); 253 int max; 254 unsigned int chunk_sectors = mddev->chunk_size >> 9; 255 unsigned int bio_sectors = bio->bi_size >> 9; 256 257 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; 258 if (max < 0) max = 0; /* bio_add cannot handle a negative return */ 259 if (max <= biovec->bv_len && bio_sectors == 0) 260 return biovec->bv_len; 261 else 262 return max; 263 } 264 265 static int raid0_run (mddev_t *mddev) 266 { 267 unsigned cur=0, i=0, nb_zone; 268 s64 size; 269 raid0_conf_t *conf; 270 mdk_rdev_t *rdev; 271 struct list_head *tmp; 272 273 if (mddev->chunk_size == 0) { 274 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n"); 275 return -EINVAL; 276 } 277 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n", 278 mdname(mddev), 279 mddev->chunk_size >> 9, 280 (mddev->chunk_size>>1)-1); 281 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); 282 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); 283 284 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); 285 if (!conf) 286 goto out; 287 mddev->private = (void *)conf; 288 289 conf->strip_zone = NULL; 290 conf->devlist = NULL; 291 if (create_strip_zones (mddev)) 292 goto out_free_conf; 293 294 /* calculate array device size */ 295 mddev->array_size = 0; 296 rdev_for_each(rdev, tmp, mddev) 297 mddev->array_size += rdev->size; 298 299 printk("raid0 : md_size is %llu blocks.\n", 300 (unsigned long long)mddev->array_size); 301 printk("raid0 : conf->hash_spacing is %llu blocks.\n", 302 (unsigned long long)conf->hash_spacing); 303 { 304 sector_t s = mddev->array_size; 305 sector_t space = conf->hash_spacing; 306 int round; 307 conf->preshift = 0; 308 if (sizeof(sector_t) > sizeof(u32)) { 309 /*shift down space and s so that sector_div will work */ 310 while (space > (sector_t) (~(u32)0)) { 311 s >>= 1; 312 space >>= 1; 313 s += 1; /* force round-up */ 314 conf->preshift++; 315 } 316 } 317 round = sector_div(s, (u32)space) ? 1 : 0; 318 nb_zone = s + round; 319 } 320 printk("raid0 : nb_zone is %d.\n", nb_zone); 321 322 printk("raid0 : Allocating %Zd bytes for hash.\n", 323 nb_zone*sizeof(struct strip_zone*)); 324 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); 325 if (!conf->hash_table) 326 goto out_free_conf; 327 size = conf->strip_zone[cur].size; 328 329 conf->hash_table[0] = conf->strip_zone + cur; 330 for (i=1; i< nb_zone; i++) { 331 while (size <= conf->hash_spacing) { 332 cur++; 333 size += conf->strip_zone[cur].size; 334 } 335 size -= conf->hash_spacing; 336 conf->hash_table[i] = conf->strip_zone + cur; 337 } 338 if (conf->preshift) { 339 conf->hash_spacing >>= conf->preshift; 340 /* round hash_spacing up so when we divide by it, we 341 * err on the side of too-low, which is safest 342 */ 343 conf->hash_spacing++; 344 } 345 346 /* calculate the max read-ahead size. 347 * For read-ahead of large files to be effective, we need to 348 * readahead at least twice a whole stripe. i.e. number of devices 349 * multiplied by chunk size times 2. 350 * If an individual device has an ra_pages greater than the 351 * chunk size, then we will not drive that device as hard as it 352 * wants. We consider this a configuration error: a larger 353 * chunksize should be used in that case. 354 */ 355 { 356 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE; 357 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 358 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 359 } 360 361 362 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 363 return 0; 364 365 out_free_conf: 366 kfree(conf->strip_zone); 367 kfree(conf->devlist); 368 kfree(conf); 369 mddev->private = NULL; 370 out: 371 return -ENOMEM; 372 } 373 374 static int raid0_stop (mddev_t *mddev) 375 { 376 raid0_conf_t *conf = mddev_to_conf(mddev); 377 378 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 379 kfree(conf->hash_table); 380 conf->hash_table = NULL; 381 kfree(conf->strip_zone); 382 conf->strip_zone = NULL; 383 kfree(conf); 384 mddev->private = NULL; 385 386 return 0; 387 } 388 389 static int raid0_make_request (struct request_queue *q, struct bio *bio) 390 { 391 mddev_t *mddev = q->queuedata; 392 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects; 393 raid0_conf_t *conf = mddev_to_conf(mddev); 394 struct strip_zone *zone; 395 mdk_rdev_t *tmp_dev; 396 sector_t chunk; 397 sector_t block, rsect; 398 const int rw = bio_data_dir(bio); 399 400 if (unlikely(bio_barrier(bio))) { 401 bio_endio(bio, -EOPNOTSUPP); 402 return 0; 403 } 404 405 disk_stat_inc(mddev->gendisk, ios[rw]); 406 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio)); 407 408 chunk_size = mddev->chunk_size >> 10; 409 chunk_sects = mddev->chunk_size >> 9; 410 chunksize_bits = ffz(~chunk_size); 411 block = bio->bi_sector >> 1; 412 413 414 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 415 struct bio_pair *bp; 416 /* Sanity check -- queue functions should prevent this happening */ 417 if (bio->bi_vcnt != 1 || 418 bio->bi_idx != 0) 419 goto bad_map; 420 /* This is a one page bio that upper layers 421 * refuse to split for us, so we need to split it. 422 */ 423 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) ); 424 if (raid0_make_request(q, &bp->bio1)) 425 generic_make_request(&bp->bio1); 426 if (raid0_make_request(q, &bp->bio2)) 427 generic_make_request(&bp->bio2); 428 429 bio_pair_release(bp); 430 return 0; 431 } 432 433 434 { 435 sector_t x = block >> conf->preshift; 436 sector_div(x, (u32)conf->hash_spacing); 437 zone = conf->hash_table[x]; 438 } 439 440 while (block >= (zone->zone_offset + zone->size)) 441 zone++; 442 443 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1); 444 445 446 { 447 sector_t x = (block - zone->zone_offset) >> chunksize_bits; 448 449 sector_div(x, zone->nb_dev); 450 chunk = x; 451 452 x = block >> chunksize_bits; 453 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 454 } 455 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1) 456 + 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_size, 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, "] zo=%d do=%d s=%d\n", 494 conf->strip_zone[j].zone_offset, 495 conf->strip_zone[j].dev_offset, 496 conf->strip_zone[j].size); 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