memcgroup: add the max_usage member on the res_counter

This field is the maximal value of the usage one since the counter creation
(or since the latest reset).

To reset this to the usage value simply write anything to the appropriate
cgroup file.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 70587657dda3..d3c61b4ebef2 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -28,6 +28,8 @@ int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
         }
 
         counter->usage += val;
+        if (counter->usage > counter->max_usage)
+                counter->max_usage = counter->usage;
         return 0;
 }
 
@@ -66,6 +68,8 @@ res_counter_member(struct res_counter *counter, int member)
         switch (member) {
         case RES_USAGE:
                 return &counter->usage;
+        case RES_MAX_USAGE:
+                return &counter->max_usage;
         case RES_LIMIT:
                 return &counter->limit;
         case RES_FAILCNT: