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 * @bvm: properties of new bio 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, 250 struct bvec_merge_data *bvm, 251 struct bio_vec *biovec) 252 { 253 mddev_t *mddev = q->queuedata; 254 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); 255 int max; 256 unsigned int chunk_sectors = mddev->chunk_size >> 9; 257 unsigned int bio_sectors = bvm->bi_size >> 9; 258 259 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; 260 if (max < 0) max = 0; /* bio_add cannot handle a negative return */ 261 if (max <= biovec->bv_len && bio_sectors == 0) 262 return biovec->bv_len; 263 else 264 return max; 265 } 266 267 static int raid0_run (mddev_t *mddev) 268 { 269 unsigned cur=0, i=0, nb_zone; 270 s64 size; 271 raid0_conf_t *conf; 272 mdk_rdev_t *rdev; 273 struct list_head *tmp; 274 275 if (mddev->chunk_size == 0) { 276 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n"); 277 return -EINVAL; 278 } 279 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n", 280 mdname(mddev), 281 mddev->chunk_size >> 9, 282 (mddev->chunk_size>>1)-1); 283 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); 284 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); 285 mddev->queue->queue_lock = &mddev->queue->__queue_lock; 286 287 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); 288 if (!conf) 289 goto out; 290 mddev->private = (void *)conf; 291 292 conf->strip_zone = NULL; 293 conf->devlist = NULL; 294 if (create_strip_zones (mddev)) 295 goto out_free_conf; 296 297 /* calculate array device size */ 298 mddev->array_sectors = 0; 299 rdev_for_each(rdev, tmp, mddev) 300 mddev->array_sectors += rdev->size * 2; 301 302 printk("raid0 : md_size is %llu blocks.\n", 303 (unsigned long long)mddev->array_sectors / 2); 304 printk("raid0 : conf->hash_spacing is %llu blocks.\n", 305 (unsigned long long)conf->hash_spacing); 306 { 307 sector_t s = mddev->array_sectors / 2; 308 sector_t space = conf->hash_spacing; 309 int round; 310 conf->preshift = 0; 311 if (sizeof(sector_t) > sizeof(u32)) { 312 /*shift down space and s so that sector_div will work */ 313 while (space > (sector_t) (~(u32)0)) { 314 s >>= 1; 315 space >>= 1; 316 s += 1; /* force round-up */ 317 conf->preshift++; 318 } 319 } 320 round = sector_div(s, (u32)space) ? 1 : 0; 321 nb_zone = s + round; 322 } 323 printk("raid0 : nb_zone is %d.\n", nb_zone); 324 325 printk("raid0 : Allocating %Zd bytes for hash.\n", 326 nb_zone*sizeof(struct strip_zone*)); 327 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); 328 if (!conf->hash_table) 329 goto out_free_conf; 330 size = conf->strip_zone[cur].size; 331 332 conf->hash_table[0] = conf->strip_zone + cur; 333 for (i=1; i< nb_zone; i++) { 334 while (size <= conf->hash_spacing) { 335 cur++; 336 size += conf->strip_zone[cur].size; 337 } 338 size -= conf->hash_spacing; 339 conf->hash_table[i] = conf->strip_zone + cur; 340 } 341 if (conf->preshift) { 342 conf->hash_spacing >>= conf->preshift; 343 /* round hash_spacing up so when we divide by it, we 344 * err on the side of too-low, which is safest 345 */ 346 conf->hash_spacing++; 347 } 348 349 /* calculate the max read-ahead size. 350 * For read-ahead of large files to be effective, we need to 351 * readahead at least twice a whole stripe. i.e. number of devices 352 * multiplied by chunk size times 2. 353 * If an individual device has an ra_pages greater than the 354 * chunk size, then we will not drive that device as hard as it 355 * wants. We consider this a configuration error: a larger 356 * chunksize should be used in that case. 357 */ 358 { 359 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE; 360 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 361 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 362 } 363 364 365 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 366 return 0; 367 368 out_free_conf: 369 kfree(conf->strip_zone); 370 kfree(conf->devlist); 371 kfree(conf); 372 mddev->private = NULL; 373 out: 374 return -ENOMEM; 375 } 376 377 static int raid0_stop (mddev_t *mddev) 378 { 379 raid0_conf_t *conf = mddev_to_conf(mddev); 380 381 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 382 kfree(conf->hash_table); 383 conf->hash_table = NULL; 384 kfree(conf->strip_zone); 385 conf->strip_zone = NULL; 386 kfree(conf); 387 mddev->private = NULL; 388 389 return 0; 390 } 391 392 static int raid0_make_request (struct request_queue *q, struct bio *bio) 393 { 394 mddev_t *mddev = q->queuedata; 395 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects; 396 raid0_conf_t *conf = mddev_to_conf(mddev); 397 struct strip_zone *zone; 398 mdk_rdev_t *tmp_dev; 399 sector_t chunk; 400 sector_t block, rsect; 401 const int rw = bio_data_dir(bio); 402 403 if (unlikely(bio_barrier(bio))) { 404 bio_endio(bio, -EOPNOTSUPP); 405 return 0; 406 } 407 408 disk_stat_inc(mddev->gendisk, ios[rw]); 409 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio)); 410 411 chunk_size = mddev->chunk_size >> 10; 412 chunk_sects = mddev->chunk_size >> 9; 413 chunksize_bits = ffz(~chunk_size); 414 block = bio->bi_sector >> 1; 415 416 417 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 418 struct bio_pair *bp; 419 /* Sanity check -- queue functions should prevent this happening */ 420 if (bio->bi_vcnt != 1 || 421 bio->bi_idx != 0) 422 goto bad_map; 423 /* This is a one page bio that upper layers 424 * refuse to split for us, so we need to split it. 425 */ 426 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) ); 427 if (raid0_make_request(q, &bp->bio1)) 428 generic_make_request(&bp->bio1); 429 if (raid0_make_request(q, &bp->bio2)) 430 generic_make_request(&bp->bio2); 431 432 bio_pair_release(bp); 433 return 0; 434 } 435 436 437 { 438 sector_t x = block >> conf->preshift; 439 sector_div(x, (u32)conf->hash_spacing); 440 zone = conf->hash_table[x]; 441 } 442 443 while (block >= (zone->zone_offset + zone->size)) 444 zone++; 445 446 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1); 447 448 449 { 450 sector_t x = (block - zone->zone_offset) >> chunksize_bits; 451 452 sector_div(x, zone->nb_dev); 453 chunk = x; 454 455 x = block >> chunksize_bits; 456 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 457 } 458 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1) 459 + sect_in_chunk; 460 461 bio->bi_bdev = tmp_dev->bdev; 462 bio->bi_sector = rsect + tmp_dev->data_offset; 463 464 /* 465 * Let the main block layer submit the IO and resolve recursion: 466 */ 467 return 1; 468 469 bad_map: 470 printk("raid0_make_request bug: can't convert block across chunks" 471 " or bigger than %dk %llu %d\n", chunk_size, 472 (unsigned long long)bio->bi_sector, bio->bi_size >> 10); 473 474 bio_io_error(bio); 475 return 0; 476 } 477 478 static void raid0_status (struct seq_file *seq, mddev_t *mddev) 479 { 480 #undef MD_DEBUG 481 #ifdef MD_DEBUG 482 int j, k, h; 483 char b[BDEVNAME_SIZE]; 484 raid0_conf_t *conf = mddev_to_conf(mddev); 485 486 h = 0; 487 for (j = 0; j < conf->nr_strip_zones; j++) { 488 seq_printf(seq, " z%d", j); 489 if (conf->hash_table[h] == conf->strip_zone+j) 490 seq_printf(seq, "(h%d)", h++); 491 seq_printf(seq, "=["); 492 for (k = 0; k < conf->strip_zone[j].nb_dev; k++) 493 seq_printf(seq, "%s/", bdevname( 494 conf->strip_zone[j].dev[k]->bdev,b)); 495 496 seq_printf(seq, "] zo=%d do=%d s=%d\n", 497 conf->strip_zone[j].zone_offset, 498 conf->strip_zone[j].dev_offset, 499 conf->strip_zone[j].size); 500 } 501 #endif 502 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); 503 return; 504 } 505 506 static struct mdk_personality raid0_personality= 507 { 508 .name = "raid0", 509 .level = 0, 510 .owner = THIS_MODULE, 511 .make_request = raid0_make_request, 512 .run = raid0_run, 513 .stop = raid0_stop, 514 .status = raid0_status, 515 }; 516 517 static int __init raid0_init (void) 518 { 519 return register_md_personality (&raid0_personality); 520 } 521 522 static void raid0_exit (void) 523 { 524 unregister_md_personality (&raid0_personality); 525 } 526 527 module_init(raid0_init); 528 module_exit(raid0_exit); 529 MODULE_LICENSE("GPL"); 530 MODULE_ALIAS("md-personality-2"); /* RAID0 */ 531 MODULE_ALIAS("md-raid0"); 532 MODULE_ALIAS("md-level-0"); 533