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dm bufio: don't take the lock in dm_bufio_shrink_count

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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 <rientjes@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mikulas Patocka 2016-11-23 16:52:01 -05:00 • committed by Greg Kroah-Hartman
parent bf4e6336cc
commit 5be6e45d18
1 changed files with 4 additions and 12 deletions
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16
drivers/md/dm-bufio.c
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@ -1574,19 +1574,11 @@ 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;
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);
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;
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);
}