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linux/drivers/md/raid0.c

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/*
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/blkdev.h>
#include <linux/seq_file.h>
#include "md.h"
#include "raid0.h"
static void raid0_unplug(struct request_queue *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++) {
struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
blk_unplug(r_queue);
}
}
static int raid0_congested(void *data, int bits)
{
mddev_t *mddev = data;
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 ; i++) {
struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
ret |= bdi_congested(&q->backing_dev_info, bits);
}
return ret;
}
static int create_strip_zones (mddev_t *mddev)
{
int i, c, j;
sector_t current_start, curr_zone_start;
sector_t min_spacing;
raid0_conf_t *conf = mddev_to_conf(mddev);
mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
struct strip_zone *zone;
int cnt;
char b[BDEVNAME_SIZE];
/*
* The number of 'same size groups'
*/
conf->nr_strip_zones = 0;
list_for_each_entry(rdev1, &mddev->disks, same_set) {
printk(KERN_INFO "raid0: looking at %s\n",
bdevname(rdev1->bdev,b));
c = 0;
list_for_each_entry(rdev2, &mddev->disks, same_set) {
printk(KERN_INFO "raid0: comparing %s(%llu)",
bdevname(rdev1->bdev,b),
(unsigned long long)rdev1->sectors);
printk(KERN_INFO " with %s(%llu)\n",
bdevname(rdev2->bdev,b),
(unsigned long long)rdev2->sectors);
if (rdev2 == rdev1) {
printk(KERN_INFO "raid0: END\n");
break;
}
if (rdev2->sectors == rdev1->sectors) {
/*
* Not unique, don't count it as a new
* group
*/
printk(KERN_INFO "raid0: EQUAL\n");
c = 1;
break;
}
printk(KERN_INFO "raid0: NOT EQUAL\n");
}
if (!c) {
printk(KERN_INFO "raid0: ==> UNIQUE\n");
conf->nr_strip_zones++;
printk(KERN_INFO "raid0: %d zones\n",
conf->nr_strip_zones);
}
}
printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
conf->nr_strip_zones, GFP_KERNEL);
if (!conf->strip_zone)
return 1;
conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
conf->nr_strip_zones*mddev->raid_disks,
GFP_KERNEL);
if (!conf->devlist)
return 1;
/* 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;
list_for_each_entry(rdev1, &mddev->disks, same_set) {
int j = rdev1->raid_disk;
if (j < 0 || j >= mddev->raid_disks) {
printk(KERN_ERR "raid0: bad disk number %d - "
"aborting!\n", j);
goto abort;
}
if (zone->dev[j]) {
printk(KERN_ERR "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->sectors < smallest->sectors))
smallest = rdev1;
cnt++;
}
if (cnt != mddev->raid_disks) {
printk(KERN_ERR "raid0: too few disks (%d of %d) - "
"aborting!\n", cnt, mddev->raid_disks);
goto abort;
}
zone->nb_dev = cnt;
zone->sectors = smallest->sectors * cnt;
zone->zone_start = 0;
current_start = smallest->sectors;
curr_zone_start = zone->sectors;
/* 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(KERN_INFO "raid0: zone %d\n", i);
zone->dev_start = current_start;
smallest = NULL;
c = 0;
for (j=0; j<cnt; j++) {
char b[BDEVNAME_SIZE];
rdev = conf->strip_zone[0].dev[j];
printk(KERN_INFO "raid0: checking %s ...",
bdevname(rdev->bdev, b));
if (rdev->sectors <= current_start) {
printk(KERN_INFO " nope.\n");
continue;
}
printk(KERN_INFO " contained as device %d\n", c);
zone->dev[c] = rdev;
c++;
if (!smallest || rdev->sectors < smallest->sectors) {
smallest = rdev;
printk(KERN_INFO " (%llu) is smallest!.\n",
(unsigned long long)rdev->sectors);
}
}
zone->nb_dev = c;
zone->sectors = (smallest->sectors - current_start) * c;
printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
zone->nb_dev, (unsigned long long)zone->sectors);
zone->zone_start = curr_zone_start;
curr_zone_start += zone->sectors;
current_start = smallest->sectors;
printk(KERN_INFO "raid0: current zone start: %llu\n",
(unsigned long long)current_start);
}
/* 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->spacing = curr_zone_start;
min_spacing = curr_zone_start;
sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
for (i=0; i < conf->nr_strip_zones-1; i++) {
sector_t s = 0;
for (j = i; j < conf->nr_strip_zones - 1 &&
s < min_spacing; j++)
s += conf->strip_zone[j].sectors;
if (s >= min_spacing && s < conf->spacing)
conf->spacing = s;
}
mddev->queue->unplug_fn = raid0_unplug;
mddev->queue->backing_dev_info.congested_fn = raid0_congested;
mddev->queue->backing_dev_info.congested_data = mddev;
printk(KERN_INFO "raid0: done.\n");
return 0;
abort:
return 1;
}
/**
* raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
* @q: request queue
* @bvm: properties of new bio
* @biovec: the request that could be merged to it.
*
* Return amount of bytes we can accept at this offset
*/
static int raid0_mergeable_bvec(struct request_queue *q,
struct bvec_merge_data *bvm,
struct bio_vec *biovec)
{
mddev_t *mddev = q->queuedata;
sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
int max;
unsigned int chunk_sectors = mddev->chunk_size >> 9;
unsigned int bio_sectors = bvm->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 sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks)
{
sector_t array_sectors = 0;
mdk_rdev_t *rdev;
WARN_ONCE(sectors || raid_disks,
"%s does not support generic reshape\n", __func__);
list_for_each_entry(rdev, &mddev->disks, same_set)
array_sectors += rdev->sectors;
return array_sectors;
}
static int raid0_run (mddev_t *mddev)
{
unsigned cur=0, i=0, nb_zone;
s64 sectors;
raid0_conf_t *conf;
if (mddev->chunk_size == 0) {
printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
return -EINVAL;
}
printk(KERN_INFO "%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);
mddev->queue->queue_lock = &mddev->queue->__queue_lock;
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 */
md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
(unsigned long long)mddev->array_sectors);
printk(KERN_INFO "raid0 : conf->spacing is %llu sectors.\n",
(unsigned long long)conf->spacing);
{
sector_t s = raid0_size(mddev, 0, 0);
sector_t space = conf->spacing;
int round;
conf->sector_shift = 0;
if (sizeof(sector_t) > sizeof(u32)) {
/*shift down space and s so that sector_div will work */
while (space > (sector_t) (~(u32)0)) {
s >>= 1;
space >>= 1;
s += 1; /* force round-up */
conf->sector_shift++;
}
}
round = sector_div(s, (u32)space) ? 1 : 0;
nb_zone = s + round;
}
printk(KERN_INFO "raid0 : nb_zone is %d.\n", nb_zone);
printk(KERN_INFO "raid0 : Allocating %zu 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;
sectors = conf->strip_zone[cur].sectors;
conf->hash_table[0] = conf->strip_zone + cur;
for (i=1; i< nb_zone; i++) {
while (sectors <= conf->spacing) {
cur++;
sectors += conf->strip_zone[cur].sectors;
}
sectors -= conf->spacing;
conf->hash_table[i] = conf->strip_zone + cur;
}
if (conf->sector_shift) {
conf->spacing >>= conf->sector_shift;
/* round spacing up so when we divide by it, we
* err on the side of too-low, which is safest
*/
conf->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_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:
kfree(conf->strip_zone);
kfree(conf->devlist);
kfree(conf);
mddev->private = NULL;
out:
return -ENOMEM;
}
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 (struct request_queue *q, struct bio *bio)
{
mddev_t *mddev = q->queuedata;
unsigned int sect_in_chunk, chunksect_bits, chunk_sects;
raid0_conf_t *conf = mddev_to_conf(mddev);
struct strip_zone *zone;
mdk_rdev_t *tmp_dev;
sector_t chunk;
sector_t sector, rsect;
const int rw = bio_data_dir(bio);
int cpu;
if (unlikely(bio_barrier(bio))) {
bio_endio(bio, -EOPNOTSUPP);
return 0;
}
cpu = part_stat_lock();
part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
bio_sectors(bio));
part_stat_unlock();
chunk_sects = mddev->chunk_size >> 9;
chunksect_bits = ffz(~chunk_sects);
sector = bio->bi_sector;
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, 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;
}
{
sector_t x = sector >> conf->sector_shift;
sector_div(x, (u32)conf->spacing);
zone = conf->hash_table[x];
}
while (sector >= zone->zone_start + zone->sectors)
zone++;
sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
{
sector_t x = (sector - zone->zone_start) >> chunksect_bits;
sector_div(x, zone->nb_dev);
chunk = x;
x = sector >> chunksect_bits;
tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
}
rsect = (chunk << chunksect_bits) + zone->dev_start + 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_sects / 2,
(unsigned long long)bio->bi_sector, bio->bi_size >> 10);
bio_io_error(bio);
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(seq, "(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, "] zs=%d ds=%d s=%d\n",
conf->strip_zone[j].zone_start,
conf->strip_zone[j].dev_start,
conf->strip_zone[j].sectors);
}
#endif
seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
return;
}
static struct mdk_personality raid0_personality=
{
.name = "raid0",
.level = 0,
.owner = THIS_MODULE,
.make_request = raid0_make_request,
.run = raid0_run,
.stop = raid0_stop,
.status = raid0_status,
.size = raid0_size,
};
static int __init raid0_init (void)
{
return register_md_personality (&raid0_personality);
}
static void raid0_exit (void)
{
unregister_md_personality (&raid0_personality);
}
module_init(raid0_init);
module_exit(raid0_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS("md-personality-2"); /* RAID0 */
MODULE_ALIAS("md-raid0");
MODULE_ALIAS("md-level-0");
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