linux/drivers/md/raid0.c
NeilBrown 5c4c33318d [PATCH] md: fix possible oops when starting a raid0 array
This loop that sets up the hash_table has problems.

Careful examination will show that the last time through, everything but
the first line is pointless.  This is because all it does is change 'cur'
and 'size' and neither of these are used after the loop.  This should ring
warning bells...  That last time through the loop,

        size += conf->strip_zone[cur].size

can index off the end of the strip_zone array.  Depending on what it finds
there, it might exit the loop cleanly, or it might spin going further and
further beyond the array until it hits an unmapped address.

This patch rearranges the code so that the last, pointless, iteration of
the loop never happens.  i.e.  the one statement of the last loop that is
needed is moved the the end of the previous loop - or to before the loop
starts - and the loop counter starts from 1 instead of 0.

Cc: "Don Dupuis" <dondster@gmail.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-23 10:35:31 -07:00

535 lines
14 KiB
C

/*
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 = 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;
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;
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);
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);
{
sector_t s = mddev->array_size;
sector_t space = conf->hash_spacing;
int round;
conf->preshift = 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->preshift++;
}
}
round = sector_div(s, (u32)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;
conf->hash_table[0] = conf->strip_zone + cur;
for (i=1; i< nb_zone; i++) {
while (size <= conf->hash_spacing) {
cur++;
size += conf->strip_zone[cur].size;
}
size -= conf->hash_spacing;
conf->hash_table[i] = conf->strip_zone + cur;
}
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_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 (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;
const int rw = bio_data_dir(bio);
if (unlikely(bio_barrier(bio))) {
bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
return 0;
}
disk_stat_inc(mddev->gendisk, ios[rw]);
disk_stat_add(mddev->gendisk, sectors[rw], 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;
}
{
sector_t x = block >> conf->preshift;
sector_div(x, (u32)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 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,
};
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");