memcg: remove MEMCG_NR_FILE_MAPPED

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 <handai.szj@taobao.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Fengguang Wu <fengguang.wu@intel.com>
Reviewed-by: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 26 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2c71f243186e..f3803462a7e6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -84,21 +84,6 @@ static int really_do_swap_account __initdata = 0;
 #endif
 
 
-/*
- * 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_RSS_HUGE,       /* # of pages charged as anon huge */
-        MEM_CGROUP_STAT_FILE_MAPPED,    /* # of pages charged as file rss */
-        MEM_CGROUP_STAT_SWAP,           /* # of pages, swapped out */
-        MEM_CGROUP_STAT_NSTATS,
-};
-
 static const char * const mem_cgroup_stat_names[] = {
         "cache",
         "rss",
@@ -2231,7 +2216,7 @@ void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
 }
 
 void mem_cgroup_update_page_stat(struct page *page,
-                                 enum mem_cgroup_page_stat_item idx, int val)
+                                 enum mem_cgroup_stat_index idx, int val)
 {
         struct mem_cgroup *memcg;
         struct page_cgroup *pc = lookup_page_cgroup(page);
@@ -2244,14 +2229,6 @@ void mem_cgroup_update_page_stat(struct page *page,
         if (unlikely(!memcg || !PageCgroupUsed(pc)))
                 return;
 
-        switch (idx) {
-        case MEMCG_NR_FILE_MAPPED:
-                idx = MEM_CGROUP_STAT_FILE_MAPPED;
-                break;
-        default:
-                BUG();
-        }
-
         this_cpu_add(memcg->stat->count[idx], val);
 }
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 07748e68b729..a21c976a8ec1 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1111,7 +1111,7 @@ void page_add_file_rmap(struct page *page)
         mem_cgroup_begin_update_page_stat(page, &locked, &flags);
         if (atomic_inc_and_test(&page->_mapcount)) {
                 __inc_zone_page_state(page, NR_FILE_MAPPED);
-                mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED);
+                mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
         }
         mem_cgroup_end_update_page_stat(page, &locked, &flags);
 }
@@ -1155,7 +1155,7 @@ void page_remove_rmap(struct page *page)
                                               NR_ANON_TRANSPARENT_HUGEPAGES);
         } else {
                 __dec_zone_page_state(page, NR_FILE_MAPPED);
-                mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED);
+                mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
                 mem_cgroup_end_update_page_stat(page, &locked, &flags);
         }
         if (unlikely(PageMlocked(page)))