mm: add Set,ClearPageSwapCache stubs

If we add NOOP stubs for SetPageSwapCache() and ClearPageSwapCache(), then
we can remove the #ifdef CONFIG_SWAPs from mm/migrate.c.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index b12f93a3c345f781b3edd26716f193efb1fdf0d4..628ec0802492dcf1a8f764ee8d86ab71f6bcf9d8 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -228,6 +228,7 @@ PAGEFLAG_FALSE(HighMem)
 PAGEFLAG(SwapCache, swapcache)
 #else
 PAGEFLAG_FALSE(SwapCache)
+       SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache)
 #endif
 
 #ifdef CONFIG_UNEVICTABLE_LRU

diff --git a/mm/migrate.c b/mm/migrate.c
index 60510306c44a50460773f49a438446729ef7d9f4..55373983c9c68410ebdb98883518e7f2b56728bd 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -300,12 +300,10 @@ static int migrate_page_move_mapping(struct address_space *mapping,
         * Now we know that no one else is looking at the page.
         */
        get_page(newpage);      /* add cache reference */
-#ifdef CONFIG_SWAP
        if (PageSwapCache(page)) {
                SetPageSwapCache(newpage);
                set_page_private(newpage, page_private(page));
        }
-#endif
 
        radix_tree_replace_slot(pslot, newpage);
 
@@ -373,9 +371,7 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
 
        mlock_migrate_page(newpage, page);
 
-#ifdef CONFIG_SWAP
        ClearPageSwapCache(page);
-#endif
        ClearPagePrivate(page);
        set_page_private(page, 0);
        /* page->mapping contains a flag for PageAnon() */