From: Sha Zhengju <redacted>

While accounting memcg page stat, it's not worth to use MEMCG_NR_FILE_MAPPED
as an extra layer of indirection because of the complexity and presumed
performance overhead. We can use MEM_CGROUP_STAT_FILE_MAPPED directly.

Signed-off-by: Sha Zhengju <redacted>
---
 include/linux/memcontrol.h |   25 +++++++++++++++++--------
 mm/memcontrol.c            |   24 +-----------------------
 mm/rmap.c                  |    4 ++--
 3 files changed, 20 insertions(+), 33 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 83e7ba9..20b0f2d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h

@@ -27,9 +27,18 @@ struct page_cgroup;
 struct page;
 struct mm_struct;
 
-/* Stats that can be updated by kernel. */
-enum mem_cgroup_page_stat_item {
-	MEMCG_NR_FILE_MAPPED, /* # of pages charged as file rss */
+/*
+ * Statistics for memory cgroup.
+ */
+enum mem_cgroup_stat_index {
+	/*
+	 * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
+	 */
+	MEM_CGROUP_STAT_CACHE, 	   /* # of pages charged as cache */
+	MEM_CGROUP_STAT_RSS,	   /* # of pages charged as anon rss */
+	MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
+	MEM_CGROUP_STAT_SWAP, /* # of pages, swapped out */
+	MEM_CGROUP_STAT_NSTATS,
 };