mm: introduce page_lru_base_type()

Instead of abusing page_is_file_cache() for LRU list index arithmetic, add
another helper with a more appropriate name and convert the non-boolean
users of page_is_file_cache() accordingly.

This new helper gives the LRU base type a page is supposed to live on,
inactive anon or inactive file.

[hugh.dickins@tiscali.co.uk: convert del_page_from_lru() also]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 4 deletions

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 7fbb97267556..99977ff45b83 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -39,21 +39,36 @@ del_page_from_lru_list(struct zone *zone, struct page *page, enum lru_list l)
         mem_cgroup_del_lru_list(page, l);
 }
 
+/**
+ * page_lru_base_type - which LRU list type should a page be on?
+ * @page: the page to test
+ *
+ * Used for LRU list index arithmetic.
+ *
+ * Returns the base LRU type - file or anon - @page should be on.
+ */
+static inline enum lru_list page_lru_base_type(struct page *page)
+{
+        if (page_is_file_cache(page))
+                return LRU_INACTIVE_FILE;
+        return LRU_INACTIVE_ANON;
+}
+
 static inline void
 del_page_from_lru(struct zone *zone, struct page *page)
 {
-        enum lru_list l = LRU_BASE;
+        enum lru_list l;
 
         list_del(&page->lru);
         if (PageUnevictable(page)) {
                 __ClearPageUnevictable(page);
                 l = LRU_UNEVICTABLE;
         } else {
+                l = page_lru_base_type(page);
                 if (PageActive(page)) {
                         __ClearPageActive(page);
                         l += LRU_ACTIVE;
                 }
-                l += page_is_file_cache(page);
         }
         __dec_zone_state(zone, NR_LRU_BASE + l);
         mem_cgroup_del_lru_list(page, l);
@@ -68,14 +83,14 @@ del_page_from_lru(struct zone *zone, struct page *page)
  */
 static inline enum lru_list page_lru(struct page *page)
 {
-        enum lru_list lru = LRU_BASE;
+        enum lru_list lru;
 
         if (PageUnevictable(page))
                 lru = LRU_UNEVICTABLE;
         else {
+                lru = page_lru_base_type(page);
                 if (PageActive(page))
                         lru += LRU_ACTIVE;
-                lru += page_is_file_cache(page);
         }
 
         return lru;