raid0.c 14.1 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115
/*
   raid0.c : Multiple Devices driver for Linux
             Copyright (C) 1994-96 Marc ZYNGIER
	     <zyngier@ufr-info-p7.ibp.fr> or
	     <maz@gloups.fdn.fr>
             Copyright (C) 1999, 2000 Ingo Molnar, Red Hat


   RAID-0 management functions.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
   
   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
*/

#include <linux/module.h>
#include <linux/raid/raid0.h>

#define MAJOR_NR MD_MAJOR
#define MD_DRIVER
#define MD_PERSONALITY

static void raid0_unplug(request_queue_t *q)
{
	mddev_t *mddev = q->queuedata;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
	int i;

	for (i=0; i<mddev->raid_disks; i++) {
		request_queue_t *r_queue = bdev_get_queue(devlist[i]->bdev);

		if (r_queue->unplug_fn)
			r_queue->unplug_fn(r_queue);
	}
}

static int raid0_issue_flush(request_queue_t *q, struct gendisk *disk,
			     sector_t *error_sector)
{
	mddev_t *mddev = q->queuedata;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
	int i, ret = 0;

	for (i=0; i<mddev->raid_disks && ret == 0; i++) {
		struct block_device *bdev = devlist[i]->bdev;
		request_queue_t *r_queue = bdev_get_queue(bdev);

		if (!r_queue->issue_flush_fn)
			ret = -EOPNOTSUPP;
		else
			ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
	}
	return ret;
}


static int create_strip_zones (mddev_t *mddev)
{
	int i, c, j;
	sector_t current_offset, curr_zone_offset;
	sector_t min_spacing;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
	struct list_head *tmp1, *tmp2;
	struct strip_zone *zone;
	int cnt;
	char b[BDEVNAME_SIZE];
 
	/*
	 * The number of 'same size groups'
	 */
	conf->nr_strip_zones = 0;
 
	ITERATE_RDEV(mddev,rdev1,tmp1) {
		printk("raid0: looking at %s\n",
			bdevname(rdev1->bdev,b));
		c = 0;
		ITERATE_RDEV(mddev,rdev2,tmp2) {
			printk("raid0:   comparing %s(%llu)",
			       bdevname(rdev1->bdev,b),
			       (unsigned long long)rdev1->size);
			printk(" with %s(%llu)\n",
			       bdevname(rdev2->bdev,b),
			       (unsigned long long)rdev2->size);
			if (rdev2 == rdev1) {
				printk("raid0:   END\n");
				break;
			}
			if (rdev2->size == rdev1->size)
			{
				/*
				 * Not unique, don't count it as a new
				 * group
				 */
				printk("raid0:   EQUAL\n");
				c = 1;
				break;
			}
			printk("raid0:   NOT EQUAL\n");
		}
		if (!c) {
			printk("raid0:   ==> UNIQUE\n");
			conf->nr_strip_zones++;
			printk("raid0: %d zones\n", conf->nr_strip_zones);
		}
	}
	printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);

116
	conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
L
Linus Torvalds 已提交
117 118 119
				conf->nr_strip_zones, GFP_KERNEL);
	if (!conf->strip_zone)
		return 1;
120
	conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
L
Linus Torvalds 已提交
121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277
				conf->nr_strip_zones*mddev->raid_disks,
				GFP_KERNEL);
	if (!conf->devlist)
		return 1;

	/* The first zone must contain all devices, so here we check that
	 * there is a proper alignment of slots to devices and find them all
	 */
	zone = &conf->strip_zone[0];
	cnt = 0;
	smallest = NULL;
	zone->dev = conf->devlist;
	ITERATE_RDEV(mddev, rdev1, tmp1) {
		int j = rdev1->raid_disk;

		if (j < 0 || j >= mddev->raid_disks) {
			printk("raid0: bad disk number %d - aborting!\n", j);
			goto abort;
		}
		if (zone->dev[j]) {
			printk("raid0: multiple devices for %d - aborting!\n",
				j);
			goto abort;
		}
		zone->dev[j] = rdev1;

		blk_queue_stack_limits(mddev->queue,
				       rdev1->bdev->bd_disk->queue);
		/* as we don't honour merge_bvec_fn, we must never risk
		 * violating it, so limit ->max_sector to one PAGE, as
		 * a one page request is never in violation.
		 */

		if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
		    mddev->queue->max_sectors > (PAGE_SIZE>>9))
			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

		if (!smallest || (rdev1->size <smallest->size))
			smallest = rdev1;
		cnt++;
	}
	if (cnt != mddev->raid_disks) {
		printk("raid0: too few disks (%d of %d) - aborting!\n",
			cnt, mddev->raid_disks);
		goto abort;
	}
	zone->nb_dev = cnt;
	zone->size = smallest->size * cnt;
	zone->zone_offset = 0;

	current_offset = smallest->size;
	curr_zone_offset = zone->size;

	/* now do the other zones */
	for (i = 1; i < conf->nr_strip_zones; i++)
	{
		zone = conf->strip_zone + i;
		zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;

		printk("raid0: zone %d\n", i);
		zone->dev_offset = current_offset;
		smallest = NULL;
		c = 0;

		for (j=0; j<cnt; j++) {
			char b[BDEVNAME_SIZE];
			rdev = conf->strip_zone[0].dev[j];
			printk("raid0: checking %s ...", bdevname(rdev->bdev,b));
			if (rdev->size > current_offset)
			{
				printk(" contained as device %d\n", c);
				zone->dev[c] = rdev;
				c++;
				if (!smallest || (rdev->size <smallest->size)) {
					smallest = rdev;
					printk("  (%llu) is smallest!.\n", 
						(unsigned long long)rdev->size);
				}
			} else
				printk(" nope.\n");
		}

		zone->nb_dev = c;
		zone->size = (smallest->size - current_offset) * c;
		printk("raid0: zone->nb_dev: %d, size: %llu\n",
			zone->nb_dev, (unsigned long long)zone->size);

		zone->zone_offset = curr_zone_offset;
		curr_zone_offset += zone->size;

		current_offset = smallest->size;
		printk("raid0: current zone offset: %llu\n",
			(unsigned long long)current_offset);
	}

	/* Now find appropriate hash spacing.
	 * We want a number which causes most hash entries to cover
	 * at most two strips, but the hash table must be at most
	 * 1 PAGE.  We choose the smallest strip, or contiguous collection
	 * of strips, that has big enough size.  We never consider the last
	 * strip though as it's size has no bearing on the efficacy of the hash
	 * table.
	 */
	conf->hash_spacing = curr_zone_offset;
	min_spacing = curr_zone_offset;
	sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
	for (i=0; i < conf->nr_strip_zones-1; i++) {
		sector_t sz = 0;
		for (j=i; j<conf->nr_strip_zones-1 &&
			     sz < min_spacing ; j++)
			sz += conf->strip_zone[j].size;
		if (sz >= min_spacing && sz < conf->hash_spacing)
			conf->hash_spacing = sz;
	}

	mddev->queue->unplug_fn = raid0_unplug;

	mddev->queue->issue_flush_fn = raid0_issue_flush;

	printk("raid0: done.\n");
	return 0;
 abort:
	return 1;
}

/**
 *	raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
 *	@q: request queue
 *	@bio: the buffer head that's been built up so far
 *	@biovec: the request that could be merged to it.
 *
 *	Return amount of bytes we can accept at this offset
 */
static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
{
	mddev_t *mddev = q->queuedata;
	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
	int max;
	unsigned int chunk_sectors = mddev->chunk_size >> 9;
	unsigned int bio_sectors = bio->bi_size >> 9;

	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
	if (max < 0) max = 0; /* bio_add cannot handle a negative return */
	if (max <= biovec->bv_len && bio_sectors == 0)
		return biovec->bv_len;
	else 
		return max;
}

static int raid0_run (mddev_t *mddev)
{
	unsigned  cur=0, i=0, nb_zone;
	s64 size;
	raid0_conf_t *conf;
	mdk_rdev_t *rdev;
	struct list_head *tmp;

278 279 280 281 282
	if (mddev->chunk_size == 0) {
		printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
		return -EINVAL;
	}
	printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
L
Linus Torvalds 已提交
283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315
	       mdname(mddev),
	       mddev->chunk_size >> 9,
	       (mddev->chunk_size>>1)-1);
	blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
	blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);

	conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
	if (!conf)
		goto out;
	mddev->private = (void *)conf;
 
	conf->strip_zone = NULL;
	conf->devlist = NULL;
	if (create_strip_zones (mddev)) 
		goto out_free_conf;

	/* calculate array device size */
	mddev->array_size = 0;
	ITERATE_RDEV(mddev,rdev,tmp)
		mddev->array_size += rdev->size;

	printk("raid0 : md_size is %llu blocks.\n", 
		(unsigned long long)mddev->array_size);
	printk("raid0 : conf->hash_spacing is %llu blocks.\n",
		(unsigned long long)conf->hash_spacing);
	{
#if __GNUC__ < 3
		volatile
#endif
		sector_t s = mddev->array_size;
		sector_t space = conf->hash_spacing;
		int round;
		conf->preshift = 0;
316
		if (sizeof(sector_t) > sizeof(u32)) {
L
Linus Torvalds 已提交
317
			/*shift down space and s so that sector_div will work */
318
			while (space > (sector_t) (~(u32)0)) {
L
Linus Torvalds 已提交
319 320 321 322 323 324
				s >>= 1;
				space >>= 1;
				s += 1; /* force round-up */
				conf->preshift++;
			}
		}
325
		round = sector_div(s, (u32)space) ? 1 : 0;
L
Linus Torvalds 已提交
326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362
		nb_zone = s + round;
	}
	printk("raid0 : nb_zone is %d.\n", nb_zone);

	printk("raid0 : Allocating %Zd bytes for hash.\n",
				nb_zone*sizeof(struct strip_zone*));
	conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
	if (!conf->hash_table)
		goto out_free_conf;
	size = conf->strip_zone[cur].size;

	for (i=0; i< nb_zone; i++) {
		conf->hash_table[i] = conf->strip_zone + cur;
		while (size <= conf->hash_spacing) {
			cur++;
			size += conf->strip_zone[cur].size;
		}
		size -= conf->hash_spacing;
	}
	if (conf->preshift) {
		conf->hash_spacing >>= conf->preshift;
		/* round hash_spacing up so when we divide by it, we
		 * err on the side of too-low, which is safest
		 */
		conf->hash_spacing++;
	}

	/* calculate the max read-ahead size.
	 * For read-ahead of large files to be effective, we need to
	 * readahead at least twice a whole stripe. i.e. number of devices
	 * multiplied by chunk size times 2.
	 * If an individual device has an ra_pages greater than the
	 * chunk size, then we will not drive that device as hard as it
	 * wants.  We consider this a configuration error: a larger
	 * chunksize should be used in that case.
	 */
	{
363
		int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
L
Linus Torvalds 已提交
364 365 366 367 368 369 370 371 372
		if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
			mddev->queue->backing_dev_info.ra_pages = 2* stripe;
	}


	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
	return 0;

out_free_conf:
373 374
	kfree(conf->strip_zone);
	kfree(conf->devlist);
L
Linus Torvalds 已提交
375 376 377 378 379 380 381 382 383 384 385
	kfree(conf);
	mddev->private = NULL;
out:
	return 1;
}

static int raid0_stop (mddev_t *mddev)
{
	raid0_conf_t *conf = mddev_to_conf(mddev);

	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
386
	kfree(conf->hash_table);
L
Linus Torvalds 已提交
387
	conf->hash_table = NULL;
388
	kfree(conf->strip_zone);
L
Linus Torvalds 已提交
389
	conf->strip_zone = NULL;
390
	kfree(conf);
L
Linus Torvalds 已提交
391 392 393 394 395 396 397 398 399 400 401 402 403 404
	mddev->private = NULL;

	return 0;
}

static int raid0_make_request (request_queue_t *q, struct bio *bio)
{
	mddev_t *mddev = q->queuedata;
	unsigned int sect_in_chunk, chunksize_bits,  chunk_size, chunk_sects;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	struct strip_zone *zone;
	mdk_rdev_t *tmp_dev;
	unsigned long chunk;
	sector_t block, rsect;
405
	const int rw = bio_data_dir(bio);
L
Linus Torvalds 已提交
406

407 408 409 410 411
	if (unlikely(bio_barrier(bio))) {
		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
		return 0;
	}

412 413
	disk_stat_inc(mddev->gendisk, ios[rw]);
	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
L
Linus Torvalds 已提交
414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445

	chunk_size = mddev->chunk_size >> 10;
	chunk_sects = mddev->chunk_size >> 9;
	chunksize_bits = ffz(~chunk_size);
	block = bio->bi_sector >> 1;
	

	if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
		struct bio_pair *bp;
		/* Sanity check -- queue functions should prevent this happening */
		if (bio->bi_vcnt != 1 ||
		    bio->bi_idx != 0)
			goto bad_map;
		/* This is a one page bio that upper layers
		 * refuse to split for us, so we need to split it.
		 */
		bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
		if (raid0_make_request(q, &bp->bio1))
			generic_make_request(&bp->bio1);
		if (raid0_make_request(q, &bp->bio2))
			generic_make_request(&bp->bio2);

		bio_pair_release(bp);
		return 0;
	}
 

	{
#if __GNUC__ < 3
		volatile
#endif
		sector_t x = block >> conf->preshift;
446
		sector_div(x, (u32)conf->hash_spacing);
L
Linus Torvalds 已提交
447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513
		zone = conf->hash_table[x];
	}
 
	while (block >= (zone->zone_offset + zone->size)) 
		zone++;
    
	sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);


	{
		sector_t x =  (block - zone->zone_offset) >> chunksize_bits;

		sector_div(x, zone->nb_dev);
		chunk = x;
		BUG_ON(x != (sector_t)chunk);

		x = block >> chunksize_bits;
		tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
	}
	rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
		+ sect_in_chunk;
 
	bio->bi_bdev = tmp_dev->bdev;
	bio->bi_sector = rsect + tmp_dev->data_offset;

	/*
	 * Let the main block layer submit the IO and resolve recursion:
	 */
	return 1;

bad_map:
	printk("raid0_make_request bug: can't convert block across chunks"
		" or bigger than %dk %llu %d\n", chunk_size, 
		(unsigned long long)bio->bi_sector, bio->bi_size >> 10);

	bio_io_error(bio, bio->bi_size);
	return 0;
}
			   
static void raid0_status (struct seq_file *seq, mddev_t *mddev)
{
#undef MD_DEBUG
#ifdef MD_DEBUG
	int j, k, h;
	char b[BDEVNAME_SIZE];
	raid0_conf_t *conf = mddev_to_conf(mddev);
  
	h = 0;
	for (j = 0; j < conf->nr_strip_zones; j++) {
		seq_printf(seq, "      z%d", j);
		if (conf->hash_table[h] == conf->strip_zone+j)
			seq_printf("(h%d)", h++);
		seq_printf(seq, "=[");
		for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
			seq_printf (seq, "%s/", bdevname(
				conf->strip_zone[j].dev[k]->bdev,b));

		seq_printf (seq, "] zo=%d do=%d s=%d\n",
				conf->strip_zone[j].zone_offset,
				conf->strip_zone[j].dev_offset,
				conf->strip_zone[j].size);
	}
#endif
	seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
	return;
}

514
static struct mdk_personality raid0_personality=
L
Linus Torvalds 已提交
515 516
{
	.name		= "raid0",
517
	.level		= 0,
L
Linus Torvalds 已提交
518 519 520 521 522 523 524 525 526
	.owner		= THIS_MODULE,
	.make_request	= raid0_make_request,
	.run		= raid0_run,
	.stop		= raid0_stop,
	.status		= raid0_status,
};

static int __init raid0_init (void)
{
527
	return register_md_personality (&raid0_personality);
L
Linus Torvalds 已提交
528 529 530 531
}

static void raid0_exit (void)
{
532
	unregister_md_personality (&raid0_personality);
L
Linus Torvalds 已提交
533 534 535 536 537 538
}

module_init(raid0_init);
module_exit(raid0_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS("md-personality-2"); /* RAID0 */
539
MODULE_ALIAS("md-level-0");