memcgroup: use triggers in force_empty and max_usage files

These two files are essentially event callbacks.  They do not care about the
contents of the string, but only about the fact of the write itself.

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

1 files changed, 6 insertions, 15 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f4079692cbf5..dc3472f9f68c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -857,27 +857,18 @@ static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
                                 mem_cgroup_write_strategy);
 }
 
-static ssize_t mem_cgroup_max_reset(struct cgroup *cont, struct cftype *cft,
-                                struct file *file, const char __user *userbuf,
-                                size_t nbytes, loff_t *ppos)
+static int mem_cgroup_max_reset(struct cgroup *cont, unsigned int event)
 {
         struct mem_cgroup *mem;
 
         mem = mem_cgroup_from_cont(cont);
         res_counter_reset_max(&mem->res);
-        return nbytes;
+        return 0;
 }
 
-static ssize_t mem_force_empty_write(struct cgroup *cont,
-                                struct cftype *cft, struct file *file,
-                                const char __user *userbuf,
-                                size_t nbytes, loff_t *ppos)
+static int mem_force_empty_write(struct cgroup *cont, unsigned int event)
 {
-        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-        int ret = mem_cgroup_force_empty(mem);
-        if (!ret)
-                ret = nbytes;
-        return ret;
+        return mem_cgroup_force_empty(mem_cgroup_from_cont(cont));
 }
 
 static const struct mem_cgroup_stat_desc {
@@ -925,7 +916,7 @@ static struct cftype mem_cgroup_files[] = {
         {
                 .name = "max_usage_in_bytes",
                 .private = RES_MAX_USAGE,
-                .write = mem_cgroup_max_reset,
+                .trigger = mem_cgroup_max_reset,
                 .read_u64 = mem_cgroup_read,
         },
         {
@@ -941,7 +932,7 @@ static struct cftype mem_cgroup_files[] = {
         },
         {
                 .name = "force_empty",
-                .write = mem_force_empty_write,
+                .trigger = mem_force_empty_write,
         },
         {
                 .name = "stat",