diff options
Diffstat (limited to 'drivers/md/raid0.c')
| -rw-r--r-- | drivers/md/raid0.c | 539 |
1 files changed, 539 insertions, 0 deletions
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c new file mode 100644 index 000000000000..e7d934eca06f --- /dev/null +++ b/drivers/md/raid0.c @@ -0,0 +1,539 @@ +/* + 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); + + conf->strip_zone = kmalloc(sizeof(struct strip_zone)* + conf->nr_strip_zones, GFP_KERNEL); + if (!conf->strip_zone) + return 1; + conf->devlist = kmalloc(sizeof(mdk_rdev_t*)* + conf->nr_strip_zones*mddev->raid_disks, + GFP_KERNEL); + if (!conf->devlist) + return 1; + + memset(conf->strip_zone, 0,sizeof(struct strip_zone)* + conf->nr_strip_zones); + memset(conf->devlist, 0, + sizeof(mdk_rdev_t*) * conf->nr_strip_zones * mddev->raid_disks); + + /* 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; + + printk("%s: setting max_sectors to %d, segment boundary to %d\n", + 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; + if (sizeof(sector_t) > sizeof(unsigned long)) { + /*shift down space and s so that sector_div will work */ + while (space > (sector_t) (~(unsigned long)0)) { + s >>= 1; + space >>= 1; + s += 1; /* force round-up */ + conf->preshift++; + } + } + round = sector_div(s, (unsigned long)space) ? 1 : 0; + 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. + */ + { + int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_CACHE_SIZE; + 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: + if (conf->strip_zone) + kfree(conf->strip_zone); + if (conf->devlist) + kfree (conf->devlist); + 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'*/ + kfree (conf->hash_table); + conf->hash_table = NULL; + kfree (conf->strip_zone); + conf->strip_zone = NULL; + kfree (conf); + 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; + + if (bio_data_dir(bio)==WRITE) { + disk_stat_inc(mddev->gendisk, writes); + disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio)); + } else { + disk_stat_inc(mddev->gendisk, reads); + disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio)); + } + + 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; + sector_div(x, (unsigned long)conf->hash_spacing); + 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; +} + +static mdk_personality_t raid0_personality= +{ + .name = "raid0", + .owner = THIS_MODULE, + .make_request = raid0_make_request, + .run = raid0_run, + .stop = raid0_stop, + .status = raid0_status, +}; + +static int __init raid0_init (void) +{ + return register_md_personality (RAID0, &raid0_personality); +} + +static void raid0_exit (void) +{ + unregister_md_personality (RAID0); +} + +module_init(raid0_init); +module_exit(raid0_exit); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("md-personality-2"); /* RAID0 */ |
