From 4779184af75437c83c7ac5f257fa0db1fe1ed9b7 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 23 Nov 2016 16:52:01 -0500 Subject: [PATCH] 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: David Rientjes Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-bufio.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index 57b01bc..c837def 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -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); } -- 2.7.4