memcg: create extensible page stat update routines

Replace usage of the mem_cgroup_update_file_mapped() memcg
statistic update routine with two new routines:
* mem_cgroup_inc_page_stat()
* mem_cgroup_dec_page_stat()

As before, only the file_mapped statistic is managed.  However, these more
general interfaces allow for new statistics to be more easily added.  New
statistics are added with memcg dirty page accounting.

Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrea Righi <arighi@develer.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index c30f33854f97..f21f4a1d6a1c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -937,7 +937,7 @@ void page_add_file_rmap(struct page *page)
 {
         if (atomic_inc_and_test(&page->_mapcount)) {
                 __inc_zone_page_state(page, NR_FILE_MAPPED);
-                mem_cgroup_update_file_mapped(page, 1);
+                mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED);
         }
 }
 
@@ -979,7 +979,7 @@ void page_remove_rmap(struct page *page)
                                               NR_ANON_TRANSPARENT_HUGEPAGES);
         } else {
                 __dec_zone_page_state(page, NR_FILE_MAPPED);
-                mem_cgroup_update_file_mapped(page, -1);
+                mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED);
         }
         /*
          * It would be tidy to reset the PageAnon mapping here,