bcache: Fix a dumb CPU spinning bug in writeback

schedule_timeout() != schedule_timeout_uninterruptible()

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>

drivers/md/bcache/writeback.c

@@ -397,8 +397,7 @@ static void read_dirty(struct closure *cl)
 		if (delay > 0 &&
 		    (KEY_START(&w->key) != dc->last_read ||
 		     jiffies_to_msecs(delay) > 50))
-			while (delay)
-				delay = schedule_timeout(delay);
+			delay = schedule_timeout_uninterruptible(delay);
 
 		dc->last_read	= KEY_OFFSET(&w->key);