FS-Cache: wake write waiter after invalidating writes

Signed-off-by: NYan, Zheng <zyan@redhat.com>
Acked-by: NDavid Howells <dhowells@redhat.com>

fs/fscache/page.c

@@ -887,6 +887,8 @@ void fscache_invalidate_writes(struct fscache_cookie *cookie)
 			put_page(results[i]);
 	}
 
+	wake_up_bit(&cookie->flags, 0);
+
 	_leave("");
 }