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>

include/linux/swap.h

@@ -177,7 +177,7 @@ extern void activate_page(struct page *);
 extern void mark_page_accessed(struct page *);
 extern void lru_add_drain(void);
 extern int lru_add_drain_all(void);
-extern int rotate_reclaimable_page(struct page *page);
+extern void rotate_reclaimable_page(struct page *page);
 extern void swap_setup(void);
 
 /* linux/mm/vmscan.c */

mm/filemap.c

@@ -576,10 +576,12 @@ EXPORT_SYMBOL(unlock_page);
  */
 void end_page_writeback(struct page *page)
 {
-	if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
+	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);
 }

mm/swap.c

@@ -132,34 +132,21 @@ static void pagevec_move_tail(struct pagevec *pvec)
  * Writeback is about to end against a page which has been marked for immediate
  * reclaim.  If it still appears to be reclaimable, move it to the tail of the
  * inactive list.
- *
- * Returns zero if it cleared PG_writeback.
  */
-int rotate_reclaimable_page(struct page *page)
+void  rotate_reclaimable_page(struct page *page)
 {
+	if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
+	    PageLRU(page)) {
 		struct pagevec *pvec;
 		unsigned long flags;
 
-	if (PageLocked(page))
-		return 1;
-	if (PageDirty(page))
-		return 1;
-	if (PageActive(page))
-		return 1;
-	if (!PageLRU(page))
-		return 1;
-
 		page_cache_get(page);
 		local_irq_save(flags);
 		pvec = &__get_cpu_var(lru_rotate_pvecs);
 		if (!pagevec_add(pvec, page))
 			pagevec_move_tail(pvec);
 		local_irq_restore(flags);
-
-	if (!test_clear_page_writeback(page))
-		BUG();
-
-	return 0;
+	}
 }
 
 /*