[PATCH v2 mmotm 3/3] swap: clean-up #ifdef in page_mapping()

[Joonsoo Kim]

PageSwapCache() is always false when !CONFIG_SWAP, so compiler
properly discard related code. Therefore, we don't need #ifdef explicitly.

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 24db914..c03c139 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -447,6 +447,7 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 
 #else /* CONFIG_SWAP */
 
+#define swap_address_space(entry)		(NULL)
 #define get_nr_swap_pages()			0L
 #define total_swap_pages			0L
 #define total_swapcache_pages()			0UL
diff --git a/mm/util.c b/mm/util.c
index 7441c41..eaf63fc2 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -388,15 +388,12 @@ struct address_space *page_mapping(struct page *page)
 	struct address_space *mapping = page->mapping;
 
 	VM_BUG_ON(PageSlab(page));
-#ifdef CONFIG_SWAP
 	if (unlikely(PageSwapCache(page))) {
 		swp_entry_t entry;
 
 		entry.val = page_private(page);
 		mapping = swap_address_space(entry);
-	} else
-#endif
-	if ((unsigned long)mapping & PAGE_MAPPING_ANON)
+	} else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
 		mapping = NULL;
 	return mapping;
 }
-- 
1.7.9.5

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