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/module.h>
22 #include <linux/raid/raid0.h>
24 #define MAJOR_NR MD_MAJOR
26 #define MD_PERSONALITY
28 static void raid0_unplug(request_queue_t *q)
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;
35 for (i=0; i<mddev->raid_disks; i++) {
36 request_queue_t *r_queue = bdev_get_queue(devlist[i]->bdev);
38 if (r_queue->unplug_fn)
39 r_queue->unplug_fn(r_queue);
43 static int raid0_issue_flush(request_queue_t *q, struct gendisk *disk,
44 sector_t *error_sector)
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;
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);
55 if (!r_queue->issue_flush_fn)
58 ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
64 static int create_strip_zones (mddev_t *mddev)
67 sector_t current_offset, curr_zone_offset;
69 raid0_conf_t *conf = mddev_to_conf(mddev);
70 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
71 struct list_head *tmp1, *tmp2;
72 struct strip_zone *zone;
74 char b[BDEVNAME_SIZE];
77 * The number of 'same size groups'
79 conf->nr_strip_zones = 0;
81 ITERATE_RDEV(mddev,rdev1,tmp1) {
82 printk("raid0: looking at %s\n",
83 bdevname(rdev1->bdev,b));
85 ITERATE_RDEV(mddev,rdev2,tmp2) {
86 printk("raid0: comparing %s(%llu)",
87 bdevname(rdev1->bdev,b),
88 (unsigned long long)rdev1->size);
89 printk(" with %s(%llu)\n",
90 bdevname(rdev2->bdev,b),
91 (unsigned long long)rdev2->size);
93 printk("raid0: END\n");
96 if (rdev2->size == rdev1->size)
99 * Not unique, don't count it as a new
102 printk("raid0: EQUAL\n");
106 printk("raid0: NOT EQUAL\n");
109 printk("raid0: ==> UNIQUE\n");
110 conf->nr_strip_zones++;
111 printk("raid0: %d zones\n", conf->nr_strip_zones);
114 printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);
116 conf->strip_zone = kmalloc(sizeof(struct strip_zone)*
117 conf->nr_strip_zones, GFP_KERNEL);
118 if (!conf->strip_zone)
120 conf->devlist = kmalloc(sizeof(mdk_rdev_t*)*
121 conf->nr_strip_zones*mddev->raid_disks,
126 memset(conf->strip_zone, 0,sizeof(struct strip_zone)*
127 conf->nr_strip_zones);
128 memset(conf->devlist, 0,
129 sizeof(mdk_rdev_t*) * conf->nr_strip_zones * mddev->raid_disks);
131 /* The first zone must contain all devices, so here we check that
132 * there is a proper alignment of slots to devices and find them all
134 zone = &conf->strip_zone[0];
137 zone->dev = conf->devlist;
138 ITERATE_RDEV(mddev, rdev1, tmp1) {
139 int j = rdev1->raid_disk;
141 if (j < 0 || j >= mddev->raid_disks) {
142 printk("raid0: bad disk number %d - aborting!\n", j);
146 printk("raid0: multiple devices for %d - aborting!\n",
150 zone->dev[j] = rdev1;
152 blk_queue_stack_limits(mddev->queue,
153 rdev1->bdev->bd_disk->queue);
154 /* as we don't honour merge_bvec_fn, we must never risk
155 * violating it, so limit ->max_sector to one PAGE, as
156 * a one page request is never in violation.
159 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
160 mddev->queue->max_sectors > (PAGE_SIZE>>9))
161 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
163 if (!smallest || (rdev1->size <smallest->size))
167 if (cnt != mddev->raid_disks) {
168 printk("raid0: too few disks (%d of %d) - aborting!\n",
169 cnt, mddev->raid_disks);
173 zone->size = smallest->size * cnt;
174 zone->zone_offset = 0;
176 current_offset = smallest->size;
177 curr_zone_offset = zone->size;
179 /* now do the other zones */
180 for (i = 1; i < conf->nr_strip_zones; i++)
182 zone = conf->strip_zone + i;
183 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
185 printk("raid0: zone %d\n", i);
186 zone->dev_offset = current_offset;
190 for (j=0; j<cnt; j++) {
191 char b[BDEVNAME_SIZE];
192 rdev = conf->strip_zone[0].dev[j];
193 printk("raid0: checking %s ...", bdevname(rdev->bdev,b));
194 if (rdev->size > current_offset)
196 printk(" contained as device %d\n", c);
199 if (!smallest || (rdev->size <smallest->size)) {
201 printk(" (%llu) is smallest!.\n",
202 (unsigned long long)rdev->size);
209 zone->size = (smallest->size - current_offset) * c;
210 printk("raid0: zone->nb_dev: %d, size: %llu\n",
211 zone->nb_dev, (unsigned long long)zone->size);
213 zone->zone_offset = curr_zone_offset;
214 curr_zone_offset += zone->size;
216 current_offset = smallest->size;
217 printk("raid0: current zone offset: %llu\n",
218 (unsigned long long)current_offset);
221 /* Now find appropriate hash spacing.
222 * We want a number which causes most hash entries to cover
223 * at most two strips, but the hash table must be at most
224 * 1 PAGE. We choose the smallest strip, or contiguous collection
225 * of strips, that has big enough size. We never consider the last
226 * strip though as it's size has no bearing on the efficacy of the hash
229 conf->hash_spacing = curr_zone_offset;
230 min_spacing = curr_zone_offset;
231 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
232 for (i=0; i < conf->nr_strip_zones-1; i++) {
234 for (j=i; j<conf->nr_strip_zones-1 &&
235 sz < min_spacing ; j++)
236 sz += conf->strip_zone[j].size;
237 if (sz >= min_spacing && sz < conf->hash_spacing)
238 conf->hash_spacing = sz;
241 mddev->queue->unplug_fn = raid0_unplug;
243 mddev->queue->issue_flush_fn = raid0_issue_flush;
245 printk("raid0: done.\n");
252 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
254 * @bio: the buffer head that's been built up so far
255 * @biovec: the request that could be merged to it.
257 * Return amount of bytes we can accept at this offset
259 static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
261 mddev_t *mddev = q->queuedata;
262 sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
264 unsigned int chunk_sectors = mddev->chunk_size >> 9;
265 unsigned int bio_sectors = bio->bi_size >> 9;
267 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
268 if (max < 0) max = 0; /* bio_add cannot handle a negative return */
269 if (max <= biovec->bv_len && bio_sectors == 0)
270 return biovec->bv_len;
275 static int raid0_run (mddev_t *mddev)
277 unsigned cur=0, i=0, nb_zone;
281 struct list_head *tmp;
283 printk("%s: setting max_sectors to %d, segment boundary to %d\n",
285 mddev->chunk_size >> 9,
286 (mddev->chunk_size>>1)-1);
287 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
288 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
290 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
293 mddev->private = (void *)conf;
295 conf->strip_zone = NULL;
296 conf->devlist = NULL;
297 if (create_strip_zones (mddev))
300 /* calculate array device size */
301 mddev->array_size = 0;
302 ITERATE_RDEV(mddev,rdev,tmp)
303 mddev->array_size += rdev->size;
305 printk("raid0 : md_size is %llu blocks.\n",
306 (unsigned long long)mddev->array_size);
307 printk("raid0 : conf->hash_spacing is %llu blocks.\n",
308 (unsigned long long)conf->hash_spacing);
313 sector_t s = mddev->array_size;
314 sector_t space = conf->hash_spacing;
317 if (sizeof(sector_t) > sizeof(unsigned long)) {
318 /*shift down space and s so that sector_div will work */
319 while (space > (sector_t) (~(unsigned long)0)) {
322 s += 1; /* force round-up */
326 round = sector_div(s, (unsigned long)space) ? 1 : 0;
329 printk("raid0 : nb_zone is %d.\n", nb_zone);
331 printk("raid0 : Allocating %Zd bytes for hash.\n",
332 nb_zone*sizeof(struct strip_zone*));
333 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
334 if (!conf->hash_table)
336 size = conf->strip_zone[cur].size;
338 for (i=0; i< nb_zone; i++) {
339 conf->hash_table[i] = conf->strip_zone + cur;
340 while (size <= conf->hash_spacing) {
342 size += conf->strip_zone[cur].size;
344 size -= conf->hash_spacing;
346 if (conf->preshift) {
347 conf->hash_spacing >>= conf->preshift;
348 /* round hash_spacing up so when we divide by it, we
349 * err on the side of too-low, which is safest
351 conf->hash_spacing++;
354 /* calculate the max read-ahead size.
355 * For read-ahead of large files to be effective, we need to
356 * readahead at least twice a whole stripe. i.e. number of devices
357 * multiplied by chunk size times 2.
358 * If an individual device has an ra_pages greater than the
359 * chunk size, then we will not drive that device as hard as it
360 * wants. We consider this a configuration error: a larger
361 * chunksize should be used in that case.
364 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_CACHE_SIZE;
365 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
366 mddev->queue->backing_dev_info.ra_pages = 2* stripe;
370 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
374 if (conf->strip_zone)
375 kfree(conf->strip_zone);
377 kfree (conf->devlist);
379 mddev->private = NULL;
384 static int raid0_stop (mddev_t *mddev)
386 raid0_conf_t *conf = mddev_to_conf(mddev);
388 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
389 kfree (conf->hash_table);
390 conf->hash_table = NULL;
391 kfree (conf->strip_zone);
392 conf->strip_zone = NULL;
394 mddev->private = NULL;
399 static int raid0_make_request (request_queue_t *q, struct bio *bio)
401 mddev_t *mddev = q->queuedata;
402 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects;
403 raid0_conf_t *conf = mddev_to_conf(mddev);
404 struct strip_zone *zone;
407 sector_t block, rsect;
409 if (bio_data_dir(bio)==WRITE) {
410 disk_stat_inc(mddev->gendisk, writes);
411 disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
413 disk_stat_inc(mddev->gendisk, reads);
414 disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
417 chunk_size = mddev->chunk_size >> 10;
418 chunk_sects = mddev->chunk_size >> 9;
419 chunksize_bits = ffz(~chunk_size);
420 block = bio->bi_sector >> 1;
423 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
425 /* Sanity check -- queue functions should prevent this happening */
426 if (bio->bi_vcnt != 1 ||
429 /* This is a one page bio that upper layers
430 * refuse to split for us, so we need to split it.
432 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
433 if (raid0_make_request(q, &bp->bio1))
434 generic_make_request(&bp->bio1);
435 if (raid0_make_request(q, &bp->bio2))
436 generic_make_request(&bp->bio2);
438 bio_pair_release(bp);
447 sector_t x = block >> conf->preshift;
448 sector_div(x, (unsigned long)conf->hash_spacing);
449 zone = conf->hash_table[x];
452 while (block >= (zone->zone_offset + zone->size))
455 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);
459 sector_t x = (block - zone->zone_offset) >> chunksize_bits;
461 sector_div(x, zone->nb_dev);
463 BUG_ON(x != (sector_t)chunk);
465 x = block >> chunksize_bits;
466 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
468 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
471 bio->bi_bdev = tmp_dev->bdev;
472 bio->bi_sector = rsect + tmp_dev->data_offset;
475 * Let the main block layer submit the IO and resolve recursion:
480 printk("raid0_make_request bug: can't convert block across chunks"
481 " or bigger than %dk %llu %d\n", chunk_size,
482 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
484 bio_io_error(bio, bio->bi_size);
488 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
493 char b[BDEVNAME_SIZE];
494 raid0_conf_t *conf = mddev_to_conf(mddev);
497 for (j = 0; j < conf->nr_strip_zones; j++) {
498 seq_printf(seq, " z%d", j);
499 if (conf->hash_table[h] == conf->strip_zone+j)
500 seq_printf("(h%d)", h++);
501 seq_printf(seq, "=[");
502 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
503 seq_printf (seq, "%s/", bdevname(
504 conf->strip_zone[j].dev[k]->bdev,b));
506 seq_printf (seq, "] zo=%d do=%d s=%d\n",
507 conf->strip_zone[j].zone_offset,
508 conf->strip_zone[j].dev_offset,
509 conf->strip_zone[j].size);
512 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
516 static mdk_personality_t raid0_personality=
519 .owner = THIS_MODULE,
520 .make_request = raid0_make_request,
523 .status = raid0_status,
526 static int __init raid0_init (void)
528 return register_md_personality (RAID0, &raid0_personality);
531 static void raid0_exit (void)
533 unregister_md_personality (RAID0);
536 module_init(raid0_init);
537 module_exit(raid0_exit);
538 MODULE_LICENSE("GPL");
539 MODULE_ALIAS("md-personality-2"); /* RAID0 */