mm: remove file argument from swap_readpage()

The file argument resulted from address_space's readpage long time ago.

We don't use it any more.  Let's remove unnecessary argement.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swap_state.c b/mm/swap_state.c
index b62e7f5..42cd38e 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -313,7 +313,7 @@
 			 * Initiate read into locked page and return.
 			 */
 			lru_cache_add_anon(new_page);
-			swap_readpage(NULL, new_page);
+			swap_readpage(new_page);
 			return new_page;
 		}
 		ClearPageSwapBacked(new_page);