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 28static 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 43static 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 63static int raid0_congested(void *data, int bits) 64{ 65 mddev_t *mddev = data; 66 raid0_conf_t *conf = mddev_to_conf(mddev); 67 mdk_rdev_t **devlist = conf->strip_zone[0].dev; 68 int i, ret = 0; 69 70 for (i = 0; i < mddev->raid_disks && !ret ; i++) { 71 request_queue_t *q = bdev_get_queue(devlist[i]->bdev); 72 73 ret |= bdi_congested(&q->backing_dev_info, bits); 74 } 75 return ret; 76} 77 78 79static int create_strip_zones (mddev_t *mddev) 80{ 81 int i, c, j; 82 sector_t current_offset, curr_zone_offset; 83 sector_t min_spacing; 84 raid0_conf_t *conf = mddev_to_conf(mddev); 85 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev; 86 struct list_head *tmp1, *tmp2; 87 struct strip_zone *zone; 88 int cnt; 89 char b[BDEVNAME_SIZE]; 90 91 /* 92 * The number of 'same size groups' 93 */ 94 conf->nr_strip_zones = 0; 95 96 ITERATE_RDEV(mddev,rdev1,tmp1) { 97 printk("raid0: looking at %s\n", 98 bdevname(rdev1->bdev,b)); 99 c = 0; 100 ITERATE_RDEV(mddev,rdev2,tmp2) { 101 printk("raid0: comparing %s(%llu)", 102 bdevname(rdev1->bdev,b), 103 (unsigned long long)rdev1->size); 104 printk(" with %s(%llu)\n", 105 bdevname(rdev2->bdev,b), 106 (unsigned long long)rdev2->size); 107 if (rdev2 == rdev1) { 108 printk("raid0: END\n"); 109 break; 110 } 111 if (rdev2->size == rdev1->size) 112 { 113 /* 114 * Not unique, don't count it as a new 115 * group 116 */ 117 printk("raid0: EQUAL\n"); 118 c = 1; 119 break; 120 } 121 printk("raid0: NOT EQUAL\n"); 122 } 123 if (!c) { 124 printk("raid0: ==> UNIQUE\n"); 125 conf->nr_strip_zones++; 126 printk("raid0: %d zones\n", conf->nr_strip_zones); 127 } 128 } 129 printk("raid0: FINAL %d zones\n", conf->nr_strip_zones); 130 131 conf->strip_zone = kzalloc(sizeof(struct strip_zone)* 132 conf->nr_strip_zones, GFP_KERNEL); 133 if (!conf->strip_zone) 134 return 1; 135 conf->devlist = kzalloc(sizeof(mdk_rdev_t*)* 136 conf->nr_strip_zones*mddev->raid_disks, 137 GFP_KERNEL); 138 if (!conf->devlist) 139 return 1; 140 141 /* The first zone must contain all devices, so here we check that 142 * there is a proper alignment of slots to devices and find them all 143 */ 144 zone = &conf->strip_zone[0]; 145 cnt = 0; 146 smallest = NULL; 147 zone->dev = conf->devlist; 148 ITERATE_RDEV(mddev, rdev1, tmp1) { 149 int j = rdev1->raid_disk; 150 151 if (j < 0 || j >= mddev->raid_disks) { 152 printk("raid0: bad disk number %d - aborting!\n", j); 153 goto abort; 154 } 155 if (zone->dev[j]) { 156 printk("raid0: multiple devices for %d - aborting!\n", 157 j); 158 goto abort; 159 } 160 zone->dev[j] = rdev1; 161 162 blk_queue_stack_limits(mddev->queue, 163 rdev1->bdev->bd_disk->queue); 164 /* as we don't honour merge_bvec_fn, we must never risk 165 * violating it, so limit ->max_sector to one PAGE, as 166 * a one page request is never in violation. 167 */ 168 169 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && 170 mddev->queue->max_sectors > (PAGE_SIZE>>9)) 171 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); 172 173 if (!smallest || (rdev1->size <smallest->size)) 174 smallest = rdev1; 175 cnt++; 176 } 177 if (cnt != mddev->raid_disks) { 178 printk("raid0: too few disks (%d of %d) - aborting!\n", 179 cnt, mddev->raid_disks); 180 goto abort; 181 } 182 zone->nb_dev = cnt; 183 zone->size = smallest->size * cnt; 184 zone->zone_offset = 0; 185 186 current_offset = smallest->size; 187 curr_zone_offset = zone->size; 188 189 /* now do the other zones */ 190 for (i = 1; i < conf->nr_strip_zones; i++) 191 { 192 zone = conf->strip_zone + i; 193 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks; 194 195 printk("raid0: zone %d\n", i); 196 zone->dev_offset = current_offset; 197 smallest = NULL; 198 c = 0; 199 200 for (j=0; j<cnt; j++) { 201 char b[BDEVNAME_SIZE]; 202 rdev = conf->strip_zone[0].dev[j]; 203 printk("raid0: checking %s ...", bdevname(rdev->bdev,b)); 204 if (rdev->size > current_offset) 205 { 206 printk(" contained as device %d\n", c); 207 zone->dev[c] = rdev; 208 c++; 209 if (!smallest || (rdev->size <smallest->size)) { 210 smallest = rdev; 211 printk(" (%llu) is smallest!.\n", 212 (unsigned long long)rdev->size); 213 } 214 } else 215 printk(" nope.\n"); 216 } 217 218 zone->nb_dev = c; 219 zone->size = (smallest->size - current_offset) * c; 220 printk("raid0: zone->nb_dev: %d, size: %llu\n", 221 zone->nb_dev, (unsigned long long)zone->size); 222 223 zone->zone_offset = curr_zone_offset; 224 curr_zone_offset += zone->size; 225 226 current_offset = smallest->size; 227 printk("raid0: current zone offset: %llu\n", 228 (unsigned long long)current_offset); 229 } 230 231 /* Now find appropriate hash spacing. 232 * We want a number which causes most hash entries to cover 233 * at most two strips, but the hash table must be at most 234 * 1 PAGE. We choose the smallest strip, or contiguous collection 235 * of strips, that has big enough size. We never consider the last 236 * strip though as it's size has no bearing on the efficacy of the hash 237 * table. 238 */ 239 conf->hash_spacing = curr_zone_offset; 240 min_spacing = curr_zone_offset; 241 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*)); 242 for (i=0; i < conf->nr_strip_zones-1; i++) { 243 sector_t sz = 0; 244 for (j=i; j<conf->nr_strip_zones-1 && 245 sz < min_spacing ; j++) 246 sz += conf->strip_zone[j].size; 247 if (sz >= min_spacing && sz < conf->hash_spacing) 248 conf->hash_spacing = sz; 249 } 250 251 mddev->queue->unplug_fn = raid0_unplug; 252 253 mddev->queue->issue_flush_fn = raid0_issue_flush; 254 mddev->queue->backing_dev_info.congested_fn = raid0_congested; 255 mddev->queue->backing_dev_info.congested_data = mddev; 256 257 printk("raid0: done.\n"); 258 return 0; 259 abort: 260 return 1; 261} 262 263/** 264 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged 265 * @q: request queue 266 * @bio: the buffer head that's been built up so far 267 * @biovec: the request that could be merged to it. 268 * 269 * Return amount of bytes we can accept at this offset 270 */ 271static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec) 272{ 273 mddev_t *mddev = q->queuedata; 274 sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev); 275 int max; 276 unsigned int chunk_sectors = mddev->chunk_size >> 9; 277 unsigned int bio_sectors = bio->bi_size >> 9; 278 279 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; 280 if (max < 0) max = 0; /* bio_add cannot handle a negative return */ 281 if (max <= biovec->bv_len && bio_sectors == 0) 282 return biovec->bv_len; 283 else 284 return max; 285} 286 287static int raid0_run (mddev_t *mddev) 288{ 289 unsigned cur=0, i=0, nb_zone; 290 s64 size; 291 raid0_conf_t *conf; 292 mdk_rdev_t *rdev; 293 struct list_head *tmp; 294 295 if (mddev->chunk_size == 0) { 296 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n"); 297 return -EINVAL; 298 } 299 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n", 300 mdname(mddev), 301 mddev->chunk_size >> 9, 302 (mddev->chunk_size>>1)-1); 303 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9); 304 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1); 305 306 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL); 307 if (!conf) 308 goto out; 309 mddev->private = (void *)conf; 310 311 conf->strip_zone = NULL; 312 conf->devlist = NULL; 313 if (create_strip_zones (mddev)) 314 goto out_free_conf; 315 316 /* calculate array device size */ 317 mddev->array_size = 0; 318 ITERATE_RDEV(mddev,rdev,tmp) 319 mddev->array_size += rdev->size; 320 321 printk("raid0 : md_size is %llu blocks.\n", 322 (unsigned long long)mddev->array_size); 323 printk("raid0 : conf->hash_spacing is %llu blocks.\n", 324 (unsigned long long)conf->hash_spacing); 325 { 326 sector_t s = mddev->array_size; 327 sector_t space = conf->hash_spacing; 328 int round; 329 conf->preshift = 0; 330 if (sizeof(sector_t) > sizeof(u32)) { 331 /*shift down space and s so that sector_div will work */ 332 while (space > (sector_t) (~(u32)0)) { 333 s >>= 1; 334 space >>= 1; 335 s += 1; /* force round-up */ 336 conf->preshift++; 337 } 338 } 339 round = sector_div(s, (u32)space) ? 1 : 0; 340 nb_zone = s + round; 341 } 342 printk("raid0 : nb_zone is %d.\n", nb_zone); 343 344 printk("raid0 : Allocating %Zd bytes for hash.\n", 345 nb_zone*sizeof(struct strip_zone*)); 346 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL); 347 if (!conf->hash_table) 348 goto out_free_conf; 349 size = conf->strip_zone[cur].size; 350 351 conf->hash_table[0] = conf->strip_zone + cur; 352 for (i=1; i< nb_zone; i++) { 353 while (size <= conf->hash_spacing) { 354 cur++; 355 size += conf->strip_zone[cur].size; 356 } 357 size -= conf->hash_spacing; 358 conf->hash_table[i] = conf->strip_zone + cur; 359 } 360 if (conf->preshift) { 361 conf->hash_spacing >>= conf->preshift; 362 /* round hash_spacing up so when we divide by it, we 363 * err on the side of too-low, which is safest 364 */ 365 conf->hash_spacing++; 366 } 367 368 /* calculate the max read-ahead size. 369 * For read-ahead of large files to be effective, we need to 370 * readahead at least twice a whole stripe. i.e. number of devices 371 * multiplied by chunk size times 2. 372 * If an individual device has an ra_pages greater than the 373 * chunk size, then we will not drive that device as hard as it 374 * wants. We consider this a configuration error: a larger 375 * chunksize should be used in that case. 376 */ 377 { 378 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE; 379 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe) 380 mddev->queue->backing_dev_info.ra_pages = 2* stripe; 381 } 382 383 384 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec); 385 return 0; 386 387out_free_conf: 388 kfree(conf->strip_zone); 389 kfree(conf->devlist); 390 kfree(conf); 391 mddev->private = NULL; 392out: 393 return -ENOMEM; 394} 395 396static int raid0_stop (mddev_t *mddev) 397{ 398 raid0_conf_t *conf = mddev_to_conf(mddev); 399 400 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ 401 kfree(conf->hash_table); 402 conf->hash_table = NULL; 403 kfree(conf->strip_zone); 404 conf->strip_zone = NULL; 405 kfree(conf); 406 mddev->private = NULL; 407 408 return 0; 409} 410 411static int raid0_make_request (request_queue_t *q, struct bio *bio) 412{ 413 mddev_t *mddev = q->queuedata; 414 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects; 415 raid0_conf_t *conf = mddev_to_conf(mddev); 416 struct strip_zone *zone; 417 mdk_rdev_t *tmp_dev; 418 sector_t chunk; 419 sector_t block, rsect; 420 const int rw = bio_data_dir(bio); 421 422 if (unlikely(bio_barrier(bio))) { 423 bio_endio(bio, bio->bi_size, -EOPNOTSUPP); 424 return 0; 425 } 426 427 disk_stat_inc(mddev->gendisk, ios[rw]); 428 disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio)); 429 430 chunk_size = mddev->chunk_size >> 10; 431 chunk_sects = mddev->chunk_size >> 9; 432 chunksize_bits = ffz(~chunk_size); 433 block = bio->bi_sector >> 1; 434 435 436 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) { 437 struct bio_pair *bp; 438 /* Sanity check -- queue functions should prevent this happening */ 439 if (bio->bi_vcnt != 1 || 440 bio->bi_idx != 0) 441 goto bad_map; 442 /* This is a one page bio that upper layers 443 * refuse to split for us, so we need to split it. 444 */ 445 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) ); 446 if (raid0_make_request(q, &bp->bio1)) 447 generic_make_request(&bp->bio1); 448 if (raid0_make_request(q, &bp->bio2)) 449 generic_make_request(&bp->bio2); 450 451 bio_pair_release(bp); 452 return 0; 453 } 454 455 456 { 457 sector_t x = block >> conf->preshift; 458 sector_div(x, (u32)conf->hash_spacing); 459 zone = conf->hash_table[x]; 460 } 461 462 while (block >= (zone->zone_offset + zone->size)) 463 zone++; 464 465 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1); 466 467 468 { 469 sector_t x = (block - zone->zone_offset) >> chunksize_bits; 470 471 sector_div(x, zone->nb_dev); 472 chunk = x; 473 474 x = block >> chunksize_bits; 475 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)]; 476 } 477 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1) 478 + sect_in_chunk; 479 480 bio->bi_bdev = tmp_dev->bdev; 481 bio->bi_sector = rsect + tmp_dev->data_offset; 482 483 /* 484 * Let the main block layer submit the IO and resolve recursion: 485 */ 486 return 1; 487 488bad_map: 489 printk("raid0_make_request bug: can't convert block across chunks" 490 " or bigger than %dk %llu %d\n", chunk_size, 491 (unsigned long long)bio->bi_sector, bio->bi_size >> 10); 492 493 bio_io_error(bio, bio->bi_size); 494 return 0; 495} 496 497static void raid0_status (struct seq_file *seq, mddev_t *mddev) 498{ 499#undef MD_DEBUG 500#ifdef MD_DEBUG 501 int j, k, h; 502 char b[BDEVNAME_SIZE]; 503 raid0_conf_t *conf = mddev_to_conf(mddev); 504 505 h = 0; 506 for (j = 0; j < conf->nr_strip_zones; j++) { 507 seq_printf(seq, " z%d", j); 508 if (conf->hash_table[h] == conf->strip_zone+j) 509 seq_printf("(h%d)", h++); 510 seq_printf(seq, "=["); 511 for (k = 0; k < conf->strip_zone[j].nb_dev; k++) 512 seq_printf (seq, "%s/", bdevname( 513 conf->strip_zone[j].dev[k]->bdev,b)); 514 515 seq_printf (seq, "] zo=%d do=%d s=%d\n", 516 conf->strip_zone[j].zone_offset, 517 conf->strip_zone[j].dev_offset, 518 conf->strip_zone[j].size); 519 } 520#endif 521 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024); 522 return; 523} 524 525static struct mdk_personality raid0_personality= 526{ 527 .name = "raid0", 528 .level = 0, 529 .owner = THIS_MODULE, 530 .make_request = raid0_make_request, 531 .run = raid0_run, 532 .stop = raid0_stop, 533 .status = raid0_status, 534}; 535 536static int __init raid0_init (void) 537{ 538 return register_md_personality (&raid0_personality); 539} 540 541static void raid0_exit (void) 542{ 543 unregister_md_personality (&raid0_personality); 544} 545 546module_init(raid0_init); 547module_exit(raid0_exit); 548MODULE_LICENSE("GPL"); 549MODULE_ALIAS("md-personality-2"); /* RAID0 */ 550MODULE_ALIAS("md-raid0"); 551MODULE_ALIAS("md-level-0"); 552