[PATCH 2/3] Memcgroup: use triggers in force_empty and max_usage files

[Pavel Emelyanov <xemul@openvz.org>]

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

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 mm/memcontrol.c |   21 ++++++---------------
 1 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c27141d..d3ec3e3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -868,27 +868,18 @@ 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 {
@@ -936,7 +927,7 @@ 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,
 	},
 	{
@@ -952,7 +943,7 @@ static struct cftype mem_cgroup_files[] = {
 	},
 	{
 		.name = "force_empty",
-		.write = mem_force_empty_write,
+		.trigger = mem_force_empty_write,
 	},
 	{
 		.name = "stat",
-- 
1.5.3.4