[PATCH] mm: schedule find_trylock_page() removal

find_trylock_page() is an odd interface in that it doesn't take a reference
like the others.  Now that XFS no longer uses it, and its last remaining
caller actually wants an elevated refcount, opencode that callsite and
schedule find_trylock_page() for removal.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 39aa9d1..e5fd538 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -397,18 +397,24 @@
 
 	p = swap_info_get(entry);
 	if (p) {
-		if (swap_entry_free(p, swp_offset(entry)) == 1)
-			page = find_trylock_page(&swapper_space, entry.val);
+		if (swap_entry_free(p, swp_offset(entry)) == 1) {
+			page = find_get_page(&swapper_space, entry.val);
+			if (page && unlikely(TestSetPageLocked(page))) {
+				page_cache_release(page);
+				page = NULL;
+			}
+		}
 		spin_unlock(&swap_lock);
 	}
 	if (page) {
 		int one_user;
 
 		BUG_ON(PagePrivate(page));
-		page_cache_get(page);
 		one_user = (page_count(page) == 2);
 		/* Only cache user (+us), or swap space full? Free it! */
-		if (!PageWriteback(page) && (one_user || vm_swap_full())) {
+		/* Also recheck PageSwapCache after page is locked (above) */
+		if (PageSwapCache(page) && !PageWriteback(page) &&
+					(one_user || vm_swap_full())) {
 			delete_from_swap_cache(page);
 			SetPageDirty(page);
 		}