memory cgroup enhancements: add memory.stat file

Show accounted information of memory cgroup by memory.stat file

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -29,6 +29,7 @@
 #include <linux/swap.h>
 #include <linux/spinlock.h>
 #include <linux/fs.h>
+#include <linux/seq_file.h>
 
 #include <asm/uaccess.h>
 
@@ -794,6 +795,49 @@ static ssize_t mem_force_empty_read(struct cgroup *cont,
 }
 
 
+static const struct mem_cgroup_stat_desc {
+	const char *msg;
+	u64 unit;
+} mem_cgroup_stat_desc[] = {
+	[MEM_CGROUP_STAT_CACHE] = { "cache", PAGE_SIZE, },
+	[MEM_CGROUP_STAT_RSS] = { "rss", PAGE_SIZE, },
+};
+
+static int mem_control_stat_show(struct seq_file *m, void *arg)
+{
+	struct cgroup *cont = m->private;
+	struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
+	struct mem_cgroup_stat *stat = &mem_cont->stat;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(stat->cpustat[0].count); i++) {
+		s64 val;
+
+		val = mem_cgroup_read_stat(stat, i);
+		val *= mem_cgroup_stat_desc[i].unit;
+		seq_printf(m, "%s %lld\n", mem_cgroup_stat_desc[i].msg,
+				(long long)val);
+	}
+	return 0;
+}
+
+static const struct file_operations mem_control_stat_file_operations = {
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int mem_control_stat_open(struct inode *unused, struct file *file)
+{
+	/* XXX __d_cont */
+	struct cgroup *cont = file->f_dentry->d_parent->d_fsdata;
+
+	file->f_op = &mem_control_stat_file_operations;
+	return single_open(file, mem_control_stat_show, cont);
+}
+
+
+
 static struct cftype mem_cgroup_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -821,6 +865,10 @@ static struct cftype mem_cgroup_files[] = {
 		.write = mem_force_empty_write,
 		.read = mem_force_empty_read,
 	},
+	{
+		.name = "stat",
+		.open = mem_control_stat_open,
+	},
 };
 
 static struct mem_cgroup init_mem_cgroup;