readahead: remove redundant test in shrink_readahead_size_eio()

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/filemap.c b/mm/filemap.c
index 734891d..2e9bcc2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1004,9 +1004,6 @@
 static void shrink_readahead_size_eio(struct file *filp,
 					struct file_ra_state *ra)
 {
-	if (!ra->ra_pages)
-		return;
-
 	ra->ra_pages /= 4;
 }