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/blkdev.h>
22 #include <linux/seq_file.h>
26 static void raid0_unplug(struct request_queue *q)
28 mddev_t *mddev = q->queuedata;
29 raid0_conf_t *conf = mddev_to_conf(mddev);
30 mdk_rdev_t **devlist = conf->strip_zone[0].dev;
33 for (i=0; i<mddev->raid_disks; i++) {
34 struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
40 static int raid0_congested(void *data, int bits)
42 mddev_t *mddev = data;
43 raid0_conf_t *conf = mddev_to_conf(mddev);
44 mdk_rdev_t **devlist = conf->strip_zone[0].dev;
47 for (i = 0; i < mddev->raid_disks && !ret ; i++) {
48 struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
50 ret |= bdi_congested(&q->backing_dev_info, bits);
55 static int create_strip_zones(mddev_t *mddev)
58 sector_t curr_zone_end, sectors;
59 mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
60 struct strip_zone *zone;
62 char b[BDEVNAME_SIZE];
63 raid0_conf_t *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
67 list_for_each_entry(rdev1, &mddev->disks, same_set) {
68 printk(KERN_INFO "raid0: looking at %s\n",
69 bdevname(rdev1->bdev,b));
71 list_for_each_entry(rdev2, &mddev->disks, same_set) {
72 printk(KERN_INFO "raid0: comparing %s(%llu)",
73 bdevname(rdev1->bdev,b),
74 (unsigned long long)rdev1->sectors);
75 printk(KERN_INFO " with %s(%llu)\n",
76 bdevname(rdev2->bdev,b),
77 (unsigned long long)rdev2->sectors);
79 printk(KERN_INFO "raid0: END\n");
82 if (rdev2->sectors == rdev1->sectors) {
84 * Not unique, don't count it as a new
87 printk(KERN_INFO "raid0: EQUAL\n");
91 printk(KERN_INFO "raid0: NOT EQUAL\n");
94 printk(KERN_INFO "raid0: ==> UNIQUE\n");
95 conf->nr_strip_zones++;
96 printk(KERN_INFO "raid0: %d zones\n",
97 conf->nr_strip_zones);
100 printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
102 conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
103 conf->nr_strip_zones, GFP_KERNEL);
104 if (!conf->strip_zone)
106 conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
107 conf->nr_strip_zones*mddev->raid_disks,
112 /* The first zone must contain all devices, so here we check that
113 * there is a proper alignment of slots to devices and find them all
115 zone = &conf->strip_zone[0];
118 zone->dev = conf->devlist;
120 list_for_each_entry(rdev1, &mddev->disks, same_set) {
121 int j = rdev1->raid_disk;
123 if (j < 0 || j >= mddev->raid_disks) {
124 printk(KERN_ERR "raid0: bad disk number %d - "
129 printk(KERN_ERR "raid0: multiple devices for %d - "
133 zone->dev[j] = rdev1;
135 blk_queue_stack_limits(mddev->queue,
136 rdev1->bdev->bd_disk->queue);
137 /* as we don't honour merge_bvec_fn, we must never risk
138 * violating it, so limit ->max_sector to one PAGE, as
139 * a one page request is never in violation.
142 if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
143 queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
144 blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
146 if (!smallest || (rdev1->sectors < smallest->sectors))
150 if (cnt != mddev->raid_disks) {
151 printk(KERN_ERR "raid0: too few disks (%d of %d) - "
152 "aborting!\n", cnt, mddev->raid_disks);
156 zone->zone_end = smallest->sectors * cnt;
158 curr_zone_end = zone->zone_end;
160 /* now do the other zones */
161 for (i = 1; i < conf->nr_strip_zones; i++)
163 zone = conf->strip_zone + i;
164 zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
166 printk(KERN_INFO "raid0: zone %d\n", i);
167 zone->dev_start = smallest->sectors;
171 for (j=0; j<cnt; j++) {
172 char b[BDEVNAME_SIZE];
173 rdev = conf->strip_zone[0].dev[j];
174 printk(KERN_INFO "raid0: checking %s ...",
175 bdevname(rdev->bdev, b));
176 if (rdev->sectors <= zone->dev_start) {
177 printk(KERN_INFO " nope.\n");
180 printk(KERN_INFO " contained as device %d\n", c);
183 if (!smallest || rdev->sectors < smallest->sectors) {
185 printk(KERN_INFO " (%llu) is smallest!.\n",
186 (unsigned long long)rdev->sectors);
191 sectors = (smallest->sectors - zone->dev_start) * c;
192 printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
193 zone->nb_dev, (unsigned long long)sectors);
195 curr_zone_end += sectors;
196 zone->zone_end = curr_zone_end;
198 printk(KERN_INFO "raid0: current zone start: %llu\n",
199 (unsigned long long)smallest->sectors);
201 mddev->queue->unplug_fn = raid0_unplug;
202 mddev->queue->backing_dev_info.congested_fn = raid0_congested;
203 mddev->queue->backing_dev_info.congested_data = mddev;
205 printk(KERN_INFO "raid0: done.\n");
206 mddev->private = conf;
209 kfree(conf->strip_zone);
210 kfree(conf->devlist);
212 mddev->private = NULL;
217 * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
219 * @bvm: properties of new bio
220 * @biovec: the request that could be merged to it.
222 * Return amount of bytes we can accept at this offset
224 static int raid0_mergeable_bvec(struct request_queue *q,
225 struct bvec_merge_data *bvm,
226 struct bio_vec *biovec)
228 mddev_t *mddev = q->queuedata;
229 sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
231 unsigned int chunk_sectors = mddev->chunk_size >> 9;
232 unsigned int bio_sectors = bvm->bi_size >> 9;
234 max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
235 if (max < 0) max = 0; /* bio_add cannot handle a negative return */
236 if (max <= biovec->bv_len && bio_sectors == 0)
237 return biovec->bv_len;
242 static sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks)
244 sector_t array_sectors = 0;
247 WARN_ONCE(sectors || raid_disks,
248 "%s does not support generic reshape\n", __func__);
250 list_for_each_entry(rdev, &mddev->disks, same_set)
251 array_sectors += rdev->sectors;
253 return array_sectors;
256 static int raid0_run(mddev_t *mddev)
260 if (mddev->chunk_size == 0) {
261 printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
264 printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
266 mddev->chunk_size >> 9,
267 (mddev->chunk_size>>1)-1);
268 blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
269 blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
270 mddev->queue->queue_lock = &mddev->queue->__queue_lock;
272 ret = create_strip_zones(mddev);
276 /* calculate array device size */
277 md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
279 printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
280 (unsigned long long)mddev->array_sectors);
281 /* calculate the max read-ahead size.
282 * For read-ahead of large files to be effective, we need to
283 * readahead at least twice a whole stripe. i.e. number of devices
284 * multiplied by chunk size times 2.
285 * If an individual device has an ra_pages greater than the
286 * chunk size, then we will not drive that device as hard as it
287 * wants. We consider this a configuration error: a larger
288 * chunksize should be used in that case.
291 int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
292 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
293 mddev->queue->backing_dev_info.ra_pages = 2* stripe;
296 blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
300 static int raid0_stop(mddev_t *mddev)
302 raid0_conf_t *conf = mddev_to_conf(mddev);
304 blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
305 kfree(conf->strip_zone);
306 kfree(conf->devlist);
308 mddev->private = NULL;
312 /* Find the zone which holds a particular offset
313 * Update *sectorp to be an offset in that zone
315 static struct strip_zone *find_zone(struct raid0_private_data *conf,
319 struct strip_zone *z = conf->strip_zone;
320 sector_t sector = *sectorp;
322 for (i = 0; i < conf->nr_strip_zones; i++)
323 if (sector < z[i].zone_end) {
325 *sectorp = sector - z[i-1].zone_end;
331 static int raid0_make_request (struct request_queue *q, struct bio *bio)
333 mddev_t *mddev = q->queuedata;
334 unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
335 raid0_conf_t *conf = mddev_to_conf(mddev);
336 struct strip_zone *zone;
339 sector_t sector, rsect, sector_offset;
340 const int rw = bio_data_dir(bio);
343 if (unlikely(bio_barrier(bio))) {
344 bio_endio(bio, -EOPNOTSUPP);
348 cpu = part_stat_lock();
349 part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
350 part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
354 chunk_sects = mddev->chunk_size >> 9;
355 chunksect_bits = ffz(~chunk_sects);
356 sector = bio->bi_sector;
358 if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
360 /* Sanity check -- queue functions should prevent this happening */
361 if (bio->bi_vcnt != 1 ||
364 /* This is a one page bio that upper layers
365 * refuse to split for us, so we need to split it.
367 bp = bio_split(bio, chunk_sects - (bio->bi_sector & (chunk_sects - 1)));
368 if (raid0_make_request(q, &bp->bio1))
369 generic_make_request(&bp->bio1);
370 if (raid0_make_request(q, &bp->bio2))
371 generic_make_request(&bp->bio2);
373 bio_pair_release(bp);
376 sector_offset = sector;
377 zone = find_zone(conf, §or_offset);
378 sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
380 sector_t x = sector_offset >> chunksect_bits;
382 sector_div(x, zone->nb_dev);
385 x = sector >> chunksect_bits;
386 tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
388 rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk;
390 bio->bi_bdev = tmp_dev->bdev;
391 bio->bi_sector = rsect + tmp_dev->data_offset;
394 * Let the main block layer submit the IO and resolve recursion:
399 printk("raid0_make_request bug: can't convert block across chunks"
400 " or bigger than %dk %llu %d\n", chunk_sects / 2,
401 (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
407 static void raid0_status (struct seq_file *seq, mddev_t *mddev)
412 char b[BDEVNAME_SIZE];
413 raid0_conf_t *conf = mddev_to_conf(mddev);
416 for (j = 0; j < conf->nr_strip_zones; j++) {
417 seq_printf(seq, " z%d", j);
418 seq_printf(seq, "=[");
419 for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
420 seq_printf(seq, "%s/", bdevname(
421 conf->strip_zone[j].dev[k]->bdev,b));
423 seq_printf(seq, "] ze=%d ds=%d s=%d\n",
424 conf->strip_zone[j].zone_end,
425 conf->strip_zone[j].dev_start,
426 conf->strip_zone[j].sectors);
429 seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
433 static struct mdk_personality raid0_personality=
437 .owner = THIS_MODULE,
438 .make_request = raid0_make_request,
441 .status = raid0_status,
445 static int __init raid0_init (void)
447 return register_md_personality (&raid0_personality);
450 static void raid0_exit (void)
452 unregister_md_personality (&raid0_personality);
455 module_init(raid0_init);
456 module_exit(raid0_exit);
457 MODULE_LICENSE("GPL");
458 MODULE_ALIAS("md-personality-2"); /* RAID0 */
459 MODULE_ALIAS("md-raid0");
460 MODULE_ALIAS("md-level-0");