FS-Cache: wake write waiter after invalidating writes

Signed-off-by: Yan, Zheng <zyan@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 3078b67..c8c4f79 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -887,6 +887,8 @@
 			put_page(results[i]);
 	}
 
+	wake_up_bit(&cookie->flags, 0);
+
 	_leave("");
 }