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md/raid5: make chunk_aligned_read() split bios more cleanly. 

chunk_aligned_read() currently uses fs_bio_set - which is meant for
filesystems to use - and loops if multiple splits are needed, which is
not best practice.
As this is only used for READ requests, not writes, it is unlikely
to cause a problem.  However it is best to be consistent in how
we split bios, and to follow the pattern used in raid1/raid10.

So create a private bioset, bio_split, and use it to perform a single
split, submitting the remainder to generic_make_request() for later
processing.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown 2017-04-05 14:05:51 +10:00 committed by Shaohua Li
parent 545250f248
commit dd7a8f5dee
2 changed files with 18 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/md/raid5.c
View File

@ -5246,24 +5246,20 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
{
struct bio *split;
sector_t sector = raid_bio->bi_iter.bi_sector;
unsigned chunk_sects = mddev->chunk_sectors;
unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
do {
sector_t sector = raid_bio->bi_iter.bi_sector;
unsigned chunk_sects = mddev->chunk_sectors;
unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
if (sectors < bio_sectors(raid_bio)) {
struct r5conf *conf = mddev->private;
split = bio_split(raid_bio, sectors, GFP_NOIO, conf->bio_split);
bio_chain(split, raid_bio);
generic_make_request(raid_bio);
raid_bio = split;
}
if (sectors < bio_sectors(raid_bio)) {
split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
bio_chain(split, raid_bio);
} else
split = raid_bio;
if (!raid5_read_one_chunk(mddev, split)) {
if (split != raid_bio)
generic_make_request(raid_bio);
return split;
}
} while (split != raid_bio);
if (!raid5_read_one_chunk(mddev, raid_bio))
return raid_bio;
return NULL;
}
@ -6747,6 +6743,8 @@ static void free_conf(struct r5conf *conf)
if (conf->disks[i].extra_page)
put_page(conf->disks[i].extra_page);
kfree(conf->disks);
if (conf->bio_split)
bioset_free(conf->bio_split);
kfree(conf->stripe_hashtbl);
kfree(conf->pending_data);
kfree(conf);
@ -6922,6 +6920,9 @@ static struct r5conf *setup_conf(struct mddev *mddev)
goto abort;
}
conf->bio_split = bioset_create(BIO_POOL_SIZE, 0);
if (!conf->bio_split)
goto abort;
conf->mddev = mddev;
if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)

1
drivers/md/raid5.h
View File

@ -646,6 +646,7 @@ struct r5conf {
int pool_size; /* number of disks in stripeheads in pool */
spinlock_t device_lock;
struct disk_info *disks;
struct bio_set *bio_split;
/* When taking over an array from a different personality, we store
* the new thread here until we fully activate the array.