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Commit 4779184a authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
Browse files

dm bufio: don't take the lock in dm_bufio_shrink_count 



commit d12067f428c037b4575aaeb2be00847fc214c24a upstream.

dm_bufio_shrink_count() is called from do_shrink_slab to find out how many
freeable objects are there. The reported value doesn't have to be precise,
so we don't need to take the dm-bufio lock.

Suggested-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9d1304f5

drivers/md/dm-bufio.c

+4 −12
Original line number Diff line number Diff line
@@ -1598,19 +1598,11 @@ dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 
static unsigned long

dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)

{

	struct dm_bufio_client *c;

	unsigned long count;

	unsigned long retain_target;



	c = container_of(shrink, struct dm_bufio_client, shrinker);

	if (sc->gfp_mask & __GFP_FS)

		dm_bufio_lock(c);

	else if (!dm_bufio_trylock(c))

		return 0;

	struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker);

	unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) +

			      READ_ONCE(c->n_buffers[LIST_DIRTY]);

	unsigned long retain_target = get_retain_buffers(c);



	count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];

	retain_target = get_retain_buffers(c);

	dm_bufio_unlock(c);

	return (count < retain_target) ? 0 : (count - retain_target);

}