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md/raid10: change read_balance to return an rdev

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It makes more sense to return an rdev than just an index as
read_balance() gets a reference to the rdev and so returning
the pointer make this more idiomatic.

This will be needed in a future patch when we might return
a 'replacement' rdev instead of the main rdev.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2011-12-23 10:17:54 +11:00
parent 69335ef3bc
commit 96c3fd1f38
1 changed files with 13 additions and 14 deletions
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27
drivers/md/raid10.c
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@ -590,7 +590,9 @@ static int raid10_mergeable_bvec(struct request_queue *q,
* FIXME: possibly should rethink readbalancing and do it differently
* depending on near_copies / far_copies geometry.
*/
static int read_balance(struct r10conf *conf, struct r10bio *r10_bio, int *max_sectors)
static struct md_rdev *read_balance(struct r10conf *conf,
struct r10bio *r10_bio,
int *max_sectors)
{
const sector_t this_sector = r10_bio->sector;
int disk, slot;
@ -703,11 +705,11 @@ retry:
}
r10_bio->read_slot = slot;
} else
disk = -1;
rdev = NULL;
rcu_read_unlock();
*max_sectors = best_good_sectors;
return disk;
return rdev;
}
static int raid10_congested(void *data, int bits)
@ -874,7 +876,6 @@ static void unfreeze_array(struct r10conf *conf)
static void make_request(struct mddev *mddev, struct bio * bio)
{
struct r10conf *conf = mddev->private;
struct mirror_info *mirror;
struct r10bio *r10_bio;
struct bio *read_bio;
int i;
@ -973,17 +974,16 @@ static void make_request(struct mddev *mddev, struct bio * bio)
/*
* read balancing logic:
*/
int disk;
struct md_rdev *rdev;
int slot;
read_again:
disk = read_balance(conf, r10_bio, &max_sectors);
slot = r10_bio->read_slot;
if (disk < 0) {
rdev = read_balance(conf, r10_bio, &max_sectors);
if (!rdev) {
raid_end_bio_io(r10_bio);
return;
}
mirror = conf->mirrors + disk;
slot = r10_bio->read_slot;
read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
md_trim_bio(read_bio, r10_bio->sector - bio->bi_sector,
@ -992,8 +992,8 @@ read_again:
r10_bio->devs[slot].bio = read_bio;
read_bio->bi_sector = r10_bio->devs[slot].addr +
mirror->rdev->data_offset;
read_bio->bi_bdev = mirror->rdev->bdev;
rdev->data_offset;
read_bio->bi_bdev = rdev->bdev;
read_bio->bi_end_io = raid10_end_read_request;
read_bio->bi_rw = READ | do_sync;
read_bio->bi_private = r10_bio;
@ -2116,8 +2116,8 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
r10_bio->devs[slot].bio =
mddev->ro ? IO_BLOCKED : NULL;
read_more:
mirror = read_balance(conf, r10_bio, &max_sectors);
if (mirror == -1) {
rdev = read_balance(conf, r10_bio, &max_sectors);
if (rdev == NULL) {
printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
" read error for block %llu\n",
mdname(mddev), b,
@ -2131,7 +2131,6 @@ read_more:
if (bio)
bio_put(bio);
slot = r10_bio->read_slot;
rdev = conf->mirrors[mirror].rdev;
printk_ratelimited(
KERN_ERR
"md/raid10:%s: %s: redirecting"