mm: rotate_reclaimable_page() cleanup

Clean up messy conditional calling of test_clear_page_writeback() from both
rotate_reclaimable_page() and end_page_writeback().

The only user of rotate_reclaimable_page() is end_page_writeback() so this is
OK.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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 07e9d92..239d361 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -576,10 +576,12 @@
  */
 void end_page_writeback(struct page *page)
 {
-	if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
-		if (!test_clear_page_writeback(page))
-			BUG();
-	}
+	if (TestClearPageReclaim(page))
+		rotate_reclaimable_page(page);
+
+	if (!test_clear_page_writeback(page))
+		BUG();
+
 	smp_mb__after_clear_bit();
 	wake_up_page(page, PG_writeback);
 }