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[PATCH] md: handle bypassing the read cache (assuming nothing fails) 

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Raz Ben-Jehuda(caro) 2006-12-10 02:20:46 -08:00 committed by Linus Torvalds
parent 23032a0eb9
commit f679623f50
1 changed files with 78 additions and 0 deletions
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78
drivers/md/raid5.c
View File

@ -2633,6 +2633,84 @@ static int raid5_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_
return max;
}
static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
{
sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
unsigned int chunk_sectors = mddev->chunk_size >> 9;
unsigned int bio_sectors = bio->bi_size >> 9;
return chunk_sectors >=
((sector & (chunk_sectors - 1)) + bio_sectors);
}
/*
* The "raid5_align_endio" should check if the read succeeded and if it
* did, call bio_endio on the original bio (having bio_put the new bio
* first).
* If the read failed..
*/
int raid5_align_endio(struct bio *bi, unsigned int bytes , int error)
{
struct bio* raid_bi = bi->bi_private;
if (bi->bi_size)
return 1;
bio_put(bi);
bio_endio(raid_bi, bytes, error);
return 0;
}
static int chunk_aligned_read(request_queue_t *q, struct bio * raid_bio)
{
mddev_t *mddev = q->queuedata;
raid5_conf_t *conf = mddev_to_conf(mddev);
const unsigned int raid_disks = conf->raid_disks;
const unsigned int data_disks = raid_disks - 1;
unsigned int dd_idx, pd_idx;
struct bio* align_bi;
mdk_rdev_t *rdev;
if (!in_chunk_boundary(mddev, raid_bio)) {
printk("chunk_aligned_read : non aligned\n");
return 0;
}
/*
* use bio_clone to make a copy of the bio
*/
align_bi = bio_clone(raid_bio, GFP_NOIO);
if (!align_bi)
return 0;
/*
* set bi_end_io to a new function, and set bi_private to the
* original bio.
*/
align_bi->bi_end_io = raid5_align_endio;
align_bi->bi_private = raid_bio;
/*
* compute position
*/
align_bi->bi_sector = raid5_compute_sector(raid_bio->bi_sector,
raid_disks,
data_disks,
&dd_idx,
&pd_idx,
conf);
rcu_read_lock();
rdev = rcu_dereference(conf->disks[dd_idx].rdev);
if (rdev && test_bit(In_sync, &rdev->flags)) {
align_bi->bi_bdev = rdev->bdev;
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
generic_make_request(align_bi);
return 1;
} else {
rcu_read_unlock();
return 0;
}
}
static int make_request(request_queue_t *q, struct bio * bi)
{
mddev_t *mddev = q->queuedata;