bcache: Fix a shrinker deadlock

commit a698e08c82dfb9771e0bac12c7337c706d729b6d upstream.

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 833c590..7d3deab 100644 (file)
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -633,7 +633,7 @@ static int bch_mca_shrink(struct shrinker *shrink, struct shrink_control *sc)
                return mca_can_free(c) * c->btree_pages;
 
        /* 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;