bcache: Fix a shrinker deadlock

GFP_NOIO means we could be getting called recursively - mca_alloc() ->
mca_data_alloc() - definitely can't use mutex_lock(bucket_lock) then.
Whoops.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 8fad8402fb2e530d970b0097e779a34164ce0260..f42fc7ed9cd63b14fd4cf54a879dfd9d046584d1 100644 (file)
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -612,7 +612,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
                return SHRINK_STOP;
 
        /* Return -1 if we can't do anything right now */
-       if (sc->gfp_mask & __GFP_WAIT)
+       if (sc->gfp_mask & __GFP_IO)
                mutex_lock(&c->bucket_lock);
        else if (!mutex_trylock(&c->bucket_lock))
                return -1;