[PATCH] splice: call handle_ra_miss() on failure to lookup page

Notify the readahead logic of the missing page. Suggested by
Oleg Nesterov.

Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/fs/splice.c b/fs/splice.c
index d7538d8..0a69164 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -302,6 +302,12 @@
 		page = find_get_page(mapping, index);
 		if (!page) {
 			/*
+			 * Make sure the read-ahead engine is notified
+			 * about this failure.
+			 */
+			handle_ra_miss(mapping, &in->f_ra, index);
+
+			/*
 			 * page didn't exist, allocate one.
 			 */
 			page = page_cache_alloc_cold(mapping);