Commit dd7a8f5d authored by NeilBrown's avatar NeilBrown Committed by Shaohua Li
Browse files

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: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 545250f2

drivers/md/raid5.c

+17 −16
Original line number Diff line number Diff line
@@ -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;



	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)) {

			split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);

		struct r5conf *conf = mddev->private;

		split = bio_split(raid_bio, sectors, GFP_NOIO, conf->bio_split);

		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;

		raid_bio = 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)

drivers/md/raid5.h

+1 −0
Original line number Diff line number Diff line
@@ -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.

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