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 create_strip_zones (mddev_t *mddev)
46 sector_t current_offset, curr_zone_offset;
48 raid0_conf_t *conf = mddev_to_conf(mddev);
49 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
50 struct list_head *tmp1, *tmp2;
51 struct strip_zone *zone;
53 char b[BDEVNAME_SIZE];
56 * The number of 'same size groups'
58 conf->nr_strip_zones = 0;
60 ITERATE_RDEV(mddev,rdev1,tmp1) {
61 printk("raid0: looking at %s\n",
62 bdevname(rdev1->bdev,b));
64 ITERATE_RDEV(mddev,rdev2,tmp2) {
65 printk("raid0: comparing %s(%llu)",
66 bdevname(rdev1->bdev,b),
67 (unsigned long long)rdev1->size);
68 printk(" with %s(%llu)\n",
69 bdevname(rdev2->bdev,b),
70 (unsigned long long)rdev2->size);
72 printk("raid0: END\n");
75 if (rdev2->size == rdev1->size)
78 * Not unique, don't count it as a new
81 printk("raid0: EQUAL\n");
85 printk("raid0: NOT EQUAL\n");
88 printk("raid0: ==> UNIQUE\n");
89 conf->nr_strip_zones++;
90 printk("raid0: %d zones\n", conf->nr_strip_zones);
93 printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);
95 conf->strip_zone = kmalloc(sizeof(struct strip_zone)*
96 conf->nr_strip_zones, GFP_KERNEL);
97 if (!conf->strip_zone)
99 conf->devlist = kmalloc(sizeof(mdk_rdev_t*)*
100 conf->nr_strip_zones*mddev->raid_disks,
105 memset(conf->strip_zone, 0,sizeof(struct strip_zone)*
106 conf->nr_strip_zones);
107 memset(conf->devlist, 0,
108 sizeof(mdk_rdev_t*) * conf->nr_strip_zones * mddev->raid_disks);
110 /* The first zone must contain all devices, so here we check that
111 * there is a proper alignment of slots to devices and find them all
113 zone = &conf->strip_zone[0];
116 zone->dev = conf->devlist;
117 ITERATE_RDEV(mddev, rdev1, tmp1) {
118 int j = rdev1->raid_disk;
120 if (j < 0 || j >= mddev->raid_disks) {
121 printk("raid0: bad disk number %d - aborting!\n", j);
125 printk("raid0: multiple devices for %d - aborting!\n",
129 zone->dev[j] = rdev1;
131 blk_queue_stack_limits(mddev->queue,
132 rdev1->bdev->bd_disk->queue);
133 /* as we don't honour merge_bvec_fn, we must never risk
134 * violating it, so limit ->max_sector to one PAGE, as
135 * a one page request is never in violation.
138 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
139 mddev->queue->max_sectors > (PAGE_SIZE>>9))
140 mddev->queue->max_sectors = (PAGE_SIZE>>9);
142 if (!smallest || (rdev1->size <smallest->size))
146 if (cnt != mddev->raid_disks) {
147 printk("raid0: too few disks (%d of %d) - aborting!\n",
148 cnt, mddev->raid_disks);
152 zone->size = smallest->size * cnt;
153 zone->zone_offset = 0;
155 current_offset = smallest->size;
156 curr_zone_offset = zone->size;
158 /* now do the other zones */
159 for (i = 1; i < conf->nr_strip_zones; i++)
161 zone = conf->strip_zone + i;
162 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
164 printk("raid0: zone %d\n", i);
165 zone->dev_offset = current_offset;
169 for (j=0; j<cnt; j++) {
170 char b[BDEVNAME_SIZE];
171 rdev = conf->strip_zone[0].dev[j];
172 printk("raid0: checking %s ...", bdevname(rdev->bdev,b));
173 if (rdev->size > current_offset)
175 printk(" contained as device %d\n", c);
178 if (!smallest || (rdev->size <smallest->size)) {
180 printk(" (%llu) is smallest!.\n",
181 (unsigned long long)rdev->size);
188 zone->size = (smallest->size - current_offset) * c;
189 printk("raid0: zone->nb_dev: %d, size: %llu\n",
190 zone->nb_dev, (unsigned long long)zone->size);
192 zone->zone_offset = curr_zone_offset;
193 curr_zone_offset += zone->size;
195 current_offset = smallest->size;
196 printk("raid0: current zone offset: %llu\n",
197 (unsigned long long)current_offset);
200 /* Now find appropriate hash spacing.
201 * We want a number which causes most hash entries to cover
202 * at most two strips, but the hash table must be at most
203 * 1 PAGE. We choose the smallest strip, or contiguous collection
204 * of strips, that has big enough size. We never consider the last
205 * strip though as it's size has no bearing on the efficacy of the hash
208 conf->hash_spacing = curr_zone_offset;
209 min_spacing = curr_zone_offset;
210 sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
211 for (i=0; i < conf->nr_strip_zones-1; i++) {
213 for (j=i; j<conf->nr_strip_zones-1 &&
214 sz < min_spacing ; j++)
215 sz += conf->strip_zone[j].size;
216 if (sz >= min_spacing && sz < conf->hash_spacing)
217 conf->hash_spacing = sz;
220 mddev->queue->unplug_fn = raid0_unplug;
222 printk("raid0: done.\n");
229 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
231 * @bio: the buffer head that's been built up so far
232 * @biovec: the request that could be merged to it.
234 * Return amount of bytes we can accept at this offset
236 static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
238 mddev_t *mddev = q->queuedata;
239 sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
241 unsigned int chunk_sectors = mddev->chunk_size >> 9;
242 unsigned int bio_sectors = bio->bi_size >> 9;
244 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
245 if (max < 0) max = 0; /* bio_add cannot handle a negative return */
246 if (max <= biovec->bv_len && bio_sectors == 0)
247 return biovec->bv_len;
252 static int raid0_run (mddev_t *mddev)
254 unsigned cur=0, i=0, nb_zone;
258 struct list_head *tmp;
260 printk("%s: setting max_sectors to %d, segment boundary to %d\n",
262 mddev->chunk_size >> 9,
263 (mddev->chunk_size>>1)-1);
264 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
265 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
267 conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
270 mddev->private = (void *)conf;
272 conf->strip_zone = NULL;
273 conf->devlist = NULL;
274 if (create_strip_zones (mddev))
277 /* calculate array device size */
278 mddev->array_size = 0;
279 ITERATE_RDEV(mddev,rdev,tmp)
280 mddev->array_size += rdev->size;
282 printk("raid0 : md_size is %llu blocks.\n",
283 (unsigned long long)mddev->array_size);
284 printk("raid0 : conf->hash_spacing is %llu blocks.\n",
285 (unsigned long long)conf->hash_spacing);
290 sector_t s = mddev->array_size;
291 sector_t space = conf->hash_spacing;
294 if (sizeof(sector_t) > sizeof(unsigned long)) {
295 /*shift down space and s so that sector_div will work */
296 while (space > (sector_t) (~(unsigned long)0)) {
299 s += 1; /* force round-up */
303 round = sector_div(s, (unsigned long)space) ? 1 : 0;
306 printk("raid0 : nb_zone is %d.\n", nb_zone);
308 printk("raid0 : Allocating %Zd bytes for hash.\n",
309 nb_zone*sizeof(struct strip_zone*));
310 conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
311 if (!conf->hash_table)
313 size = conf->strip_zone[cur].size;
315 for (i=0; i< nb_zone; i++) {
316 conf->hash_table[i] = conf->strip_zone + cur;
317 while (size <= conf->hash_spacing) {
319 size += conf->strip_zone[cur].size;
321 size -= conf->hash_spacing;
323 if (conf->preshift) {
324 conf->hash_spacing >>= conf->preshift;
325 /* round hash_spacing up so when we divide by it, we
326 * err on the side of too-low, which is safest
328 conf->hash_spacing++;
331 /* calculate the max read-ahead size.
332 * For read-ahead of large files to be effective, we need to
333 * readahead at least twice a whole stripe. i.e. number of devices
334 * multiplied by chunk size times 2.
335 * If an individual device has an ra_pages greater than the
336 * chunk size, then we will not drive that device as hard as it
337 * wants. We consider this a configuration error: a larger
338 * chunksize should be used in that case.
341 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_CACHE_SIZE;
342 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
343 mddev->queue->backing_dev_info.ra_pages = 2* stripe;
347 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
351 if (conf->strip_zone)
352 kfree(conf->strip_zone);
354 kfree (conf->devlist);
356 mddev->private = NULL;
361 static int raid0_stop (mddev_t *mddev)
363 raid0_conf_t *conf = mddev_to_conf(mddev);
365 kfree (conf->hash_table);
366 conf->hash_table = NULL;
367 kfree (conf->strip_zone);
368 conf->strip_zone = NULL;
370 mddev->private = NULL;
375 static int raid0_make_request (request_queue_t *q, struct bio *bio)
377 mddev_t *mddev = q->queuedata;
378 unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects;
379 raid0_conf_t *conf = mddev_to_conf(mddev);
380 struct strip_zone *zone;
383 sector_t block, rsect;
385 if (bio_data_dir(bio)==WRITE) {
386 disk_stat_inc(mddev->gendisk, writes);
387 disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
389 disk_stat_inc(mddev->gendisk, reads);
390 disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
393 chunk_size = mddev->chunk_size >> 10;
394 chunk_sects = mddev->chunk_size >> 9;
395 chunksize_bits = ffz(~chunk_size);
396 block = bio->bi_sector >> 1;
399 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
401 /* Sanity check -- queue functions should prevent this happening */
402 if (bio->bi_vcnt != 1 ||
405 /* This is a one page bio that upper layers
406 * refuse to split for us, so we need to split it.
408 bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
409 if (raid0_make_request(q, &bp->bio1))
410 generic_make_request(&bp->bio1);
411 if (raid0_make_request(q, &bp->bio2))
412 generic_make_request(&bp->bio2);
414 bio_pair_release(bp);
423 sector_t x = block >> conf->preshift;
424 sector_div(x, (unsigned long)conf->hash_spacing);
425 zone = conf->hash_table[x];
428 while (block >= (zone->zone_offset + zone->size))
431 sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);
435 sector_t x = (block - zone->zone_offset) >> chunksize_bits;
437 sector_div(x, zone->nb_dev);
439 BUG_ON(x != (sector_t)chunk);
441 x = block >> chunksize_bits;
442 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
444 rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
447 bio->bi_bdev = tmp_dev->bdev;
448 bio->bi_sector = rsect + tmp_dev->data_offset;
451 * Let the main block layer submit the IO and resolve recursion:
456 printk("raid0_make_request bug: can't convert block across chunks"
457 " or bigger than %dk %llu %d\n", chunk_size,
458 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
460 bio_io_error(bio, bio->bi_size);
464 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
469 char b[BDEVNAME_SIZE];
470 raid0_conf_t *conf = mddev_to_conf(mddev);
473 for (j = 0; j < conf->nr_strip_zones; j++) {
474 seq_printf(seq, " z%d", j);
475 if (conf->hash_table[h] == conf->strip_zone+j)
476 seq_printf("(h%d)", h++);
477 seq_printf(seq, "=[");
478 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
479 seq_printf (seq, "%s/", bdevname(
480 conf->strip_zone[j].dev[k]->bdev,b));
482 seq_printf (seq, "] zo=%d do=%d s=%d\n",
483 conf->strip_zone[j].zone_offset,
484 conf->strip_zone[j].dev_offset,
485 conf->strip_zone[j].size);
488 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
492 static mdk_personality_t raid0_personality=
495 .owner = THIS_MODULE,
496 .make_request = raid0_make_request,
499 .status = raid0_status,
502 static int __init raid0_init (void)
504 return register_md_personality (RAID0, &raid0_personality);
507 static void raid0_exit (void)
509 unregister_md_personality (RAID0);
512 module_init(raid0_init);
513 module_exit(raid0_exit);
514 MODULE_LICENSE("GPL");
515 MODULE_ALIAS("md-personality-2"); /* RAID0 */