2 raid0.c : Multiple Devices driver for Linux
3 Copyright (C) 1994-96 Marc ZYNGIER
4 <zyngier@ufr-info-p7.ibp.fr> or
6 Copyright (C) 1999, 2000 Ingo Molnar, Red Hat
9 RAID-0 management functions.
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)
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.
21 #include <linux/raid/raid0.h>
23 static void raid0_unplug(struct request_queue *q)
25 mddev_t *mddev = q->queuedata;
26 raid0_conf_t *conf = mddev_to_conf(mddev);
27 mdk_rdev_t **devlist = conf->strip_zone[0].dev;
30 for (i=0; i<mddev->raid_disks; i++) {
31 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
37 static int raid0_congested(void *data, int bits)
39 mddev_t *mddev = data;
40 raid0_conf_t *conf = mddev_to_conf(mddev);
41 mdk_rdev_t **devlist = conf->strip_zone[0].dev;
44 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
45 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
47 ret |= bdi_congested(&q->backing_dev_info, bits);
53 static int create_strip_zones (mddev_t *mddev)
56 sector_t current_start, curr_zone_start;
58 raid0_conf_t *conf = mddev_to_conf(mddev);
59 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
60 struct strip_zone *zone;
62 char b[BDEVNAME_SIZE];
65 * The number of 'same size groups'
67 conf->nr_strip_zones = 0;
69 list_for_each_entry(rdev1, &mddev->disks, same_set) {
70 printk(KERN_INFO "raid0: looking at %s\n",
71 bdevname(rdev1->bdev,b));
73 list_for_each_entry(rdev2, &mddev->disks, same_set) {
74 printk(KERN_INFO "raid0: comparing %s(%llu)",
75 bdevname(rdev1->bdev,b),
76 (unsigned long long)rdev1->size);
77 printk(KERN_INFO " with %s(%llu)\n",
78 bdevname(rdev2->bdev,b),
79 (unsigned long long)rdev2->size);
81 printk(KERN_INFO "raid0: END\n");
84 if (rdev2->size == rdev1->size)
87 * Not unique, don't count it as a new
90 printk(KERN_INFO "raid0: EQUAL\n");
94 printk(KERN_INFO "raid0: NOT EQUAL\n");
97 printk(KERN_INFO "raid0: ==> UNIQUE\n");
98 conf->nr_strip_zones++;
99 printk(KERN_INFO "raid0: %d zones\n",
100 conf->nr_strip_zones);
103 printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
105 conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
106 conf->nr_strip_zones, GFP_KERNEL);
107 if (!conf->strip_zone)
109 conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
110 conf->nr_strip_zones*mddev->raid_disks,
115 /* The first zone must contain all devices, so here we check that
116 * there is a proper alignment of slots to devices and find them all
118 zone = &conf->strip_zone[0];
121 zone->dev = conf->devlist;
122 list_for_each_entry(rdev1, &mddev->disks, same_set) {
123 int j = rdev1->raid_disk;
125 if (j < 0 || j >= mddev->raid_disks) {
126 printk(KERN_ERR "raid0: bad disk number %d - "
131 printk(KERN_ERR "raid0: multiple devices for %d - "
135 zone->dev[j] = rdev1;
137 blk_queue_stack_limits(mddev->queue,
138 rdev1->bdev->bd_disk->queue);
139 /* as we don't honour merge_bvec_fn, we must never risk
140 * violating it, so limit ->max_sector to one PAGE, as
141 * a one page request is never in violation.
144 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
145 mddev->queue->max_sectors > (PAGE_SIZE>>9))
146 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
148 if (!smallest || (rdev1->size <smallest->size))
152 if (cnt != mddev->raid_disks) {
153 printk(KERN_ERR "raid0: too few disks (%d of %d) - "
154 "aborting!\n", cnt, mddev->raid_disks);
158 zone->sectors = smallest->size * cnt * 2;
159 zone->zone_start = 0;
161 current_start = smallest->size * 2;
162 curr_zone_start = zone->sectors;
164 /* now do the other zones */
165 for (i = 1; i < conf->nr_strip_zones; i++)
167 zone = conf->strip_zone + i;
168 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
170 printk(KERN_INFO "raid0: zone %d\n", i);
171 zone->dev_start = current_start;
175 for (j=0; j<cnt; j++) {
176 char b[BDEVNAME_SIZE];
177 rdev = conf->strip_zone[0].dev[j];
178 printk(KERN_INFO "raid0: checking %s ...",
179 bdevname(rdev->bdev, b));
180 if (rdev->size > current_start / 2) {
181 printk(KERN_INFO " contained as device %d\n",
185 if (!smallest || (rdev->size <smallest->size)) {
187 printk(KERN_INFO " (%llu) is smallest!.\n",
188 (unsigned long long)rdev->size);
191 printk(KERN_INFO " nope.\n");
195 zone->sectors = (smallest->size * 2 - current_start) * c;
196 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
197 zone->nb_dev, (unsigned long long)zone->sectors);
199 zone->zone_start = curr_zone_start;
200 curr_zone_start += zone->sectors;
202 current_start = smallest->size * 2;
203 printk(KERN_INFO "raid0: current zone start: %llu\n",
204 (unsigned long long)current_start);
207 /* Now find appropriate hash spacing.
208 * We want a number which causes most hash entries to cover
209 * at most two strips, but the hash table must be at most
210 * 1 PAGE. We choose the smallest strip, or contiguous collection
211 * of strips, that has big enough size. We never consider the last
212 * strip though as it's size has no bearing on the efficacy of the hash
215 conf->spacing = curr_zone_start;
216 min_spacing = curr_zone_start;
217 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
218 for (i=0; i < conf->nr_strip_zones-1; i++) {
220 for (j = i; j < conf->nr_strip_zones - 1 &&
221 s < min_spacing; j++)
222 s += conf->strip_zone[j].sectors;
223 if (s >= min_spacing && s < conf->spacing)
227 mddev->queue->unplug_fn = raid0_unplug;
229 mddev->queue->backing_dev_info.congested_fn = raid0_congested;
230 mddev->queue->backing_dev_info.congested_data = mddev;
232 printk(KERN_INFO "raid0: done.\n");
239 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
241 * @bvm: properties of new bio
242 * @biovec: the request that could be merged to it.
244 * Return amount of bytes we can accept at this offset
246 static int raid0_mergeable_bvec(struct request_queue *q,
247 struct bvec_merge_data *bvm,
248 struct bio_vec *biovec)
250 mddev_t *mddev = q->queuedata;
251 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
253 unsigned int chunk_sectors = mddev->chunk_size >> 9;
254 unsigned int bio_sectors = bvm->bi_size >> 9;
256 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
257 if (max < 0) max = 0; /* bio_add cannot handle a negative return */
258 if (max <= biovec->bv_len && bio_sectors == 0)
259 return biovec->bv_len;
264 static int raid0_run (mddev_t *mddev)
266 unsigned cur=0, i=0, nb_zone;
271 if (mddev->chunk_size == 0) {
272 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
275 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
277 mddev->chunk_size >> 9,
278 (mddev->chunk_size>>1)-1);
279 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
280 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
281 mddev->queue->queue_lock = &mddev->queue->__queue_lock;
283 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
286 mddev->private = (void *)conf;
288 conf->strip_zone = NULL;
289 conf->devlist = NULL;
290 if (create_strip_zones (mddev))
293 /* calculate array device size */
294 mddev->array_sectors = 0;
295 list_for_each_entry(rdev, &mddev->disks, same_set)
296 mddev->array_sectors += rdev->size * 2;
298 printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
299 (unsigned long long)mddev->array_sectors);
300 printk(KERN_INFO "raid0 : conf->spacing is %llu sectors.\n",
301 (unsigned long long)conf->spacing);
303 sector_t s = mddev->array_sectors;
304 sector_t space = conf->spacing;
306 conf->sector_shift = 0;
307 if (sizeof(sector_t) > sizeof(u32)) {
308 /*shift down space and s so that sector_div will work */
309 while (space > (sector_t) (~(u32)0)) {
312 s += 1; /* force round-up */
313 conf->sector_shift++;
316 round = sector_div(s, (u32)space) ? 1 : 0;
319 printk(KERN_INFO "raid0 : nb_zone is %d.\n", nb_zone);
321 printk(KERN_INFO "raid0 : Allocating %zu bytes for hash.\n",
322 nb_zone*sizeof(struct strip_zone*));
323 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
324 if (!conf->hash_table)
326 sectors = conf->strip_zone[cur].sectors;
328 conf->hash_table[0] = conf->strip_zone + cur;
329 for (i=1; i< nb_zone; i++) {
330 while (sectors <= conf->spacing) {
332 sectors += conf->strip_zone[cur].sectors;
334 sectors -= conf->spacing;
335 conf->hash_table[i] = conf->strip_zone + cur;
337 if (conf->sector_shift) {
338 conf->spacing >>= conf->sector_shift;
339 /* round spacing up so when we divide by it, we
340 * err on the side of too-low, which is safest
345 /* calculate the max read-ahead size.
346 * For read-ahead of large files to be effective, we need to
347 * readahead at least twice a whole stripe. i.e. number of devices
348 * multiplied by chunk size times 2.
349 * If an individual device has an ra_pages greater than the
350 * chunk size, then we will not drive that device as hard as it
351 * wants. We consider this a configuration error: a larger
352 * chunksize should be used in that case.
355 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
356 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
357 mddev->queue->backing_dev_info.ra_pages = 2* stripe;
361 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
365 kfree(conf->strip_zone);
366 kfree(conf->devlist);
368 mddev->private = NULL;
373 static int raid0_stop (mddev_t *mddev)
375 raid0_conf_t *conf = mddev_to_conf(mddev);
377 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
378 kfree(conf->hash_table);
379 conf->hash_table = NULL;
380 kfree(conf->strip_zone);
381 conf->strip_zone = NULL;
383 mddev->private = NULL;
388 static int raid0_make_request (struct request_queue *q, struct bio *bio)
390 mddev_t *mddev = q->queuedata;
391 unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
392 raid0_conf_t *conf = mddev_to_conf(mddev);
393 struct strip_zone *zone;
396 sector_t sector, rsect;
397 const int rw = bio_data_dir(bio);
400 if (unlikely(bio_barrier(bio))) {
401 bio_endio(bio, -EOPNOTSUPP);
405 cpu = part_stat_lock();
406 part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
407 part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
411 chunk_sects = mddev->chunk_size >> 9;
412 chunksect_bits = ffz(~chunk_sects);
413 sector = bio->bi_sector;
415 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
417 /* Sanity check -- queue functions should prevent this happening */
418 if (bio->bi_vcnt != 1 ||
421 /* This is a one page bio that upper layers
422 * refuse to split for us, so we need to split it.
424 bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1)));
425 if (raid0_make_request(q, &bp->bio1))
426 generic_make_request(&bp->bio1);
427 if (raid0_make_request(q, &bp->bio2))
428 generic_make_request(&bp->bio2);
430 bio_pair_release(bp);
436 sector_t x = sector >> conf->sector_shift;
437 sector_div(x, (u32)conf->spacing);
438 zone = conf->hash_table[x];
441 while (sector >= zone->zone_start + zone->sectors)
444 sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
448 sector_t x = (sector - zone->zone_start) >> chunksect_bits;
450 sector_div(x, zone->nb_dev);
453 x = sector >> chunksect_bits;
454 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
456 rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk;
458 bio->bi_bdev = tmp_dev->bdev;
459 bio->bi_sector = rsect + tmp_dev->data_offset;
462 * Let the main block layer submit the IO and resolve recursion:
467 printk("raid0_make_request bug: can't convert block across chunks"
468 " or bigger than %dk %llu %d\n", chunk_sects / 2,
469 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
475 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
480 char b[BDEVNAME_SIZE];
481 raid0_conf_t *conf = mddev_to_conf(mddev);
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));
493 seq_printf(seq, "] zs=%d ds=%d s=%d\n",
494 conf->strip_zone[j].zone_start,
495 conf->strip_zone[j].dev_start,
496 conf->strip_zone[j].sectors);
499 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
503 static struct mdk_personality raid0_personality=
507 .owner = THIS_MODULE,
508 .make_request = raid0_make_request,
511 .status = raid0_status,
514 static int __init raid0_init (void)
516 return register_md_personality (&raid0_personality);
519 static void raid0_exit (void)
521 unregister_md_personality (&raid0_personality);
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");