[PATCH 1/4] swapcgroup: add cgroup files

[Daisuke Nishimura <nishimura-YQH0OdQVrdy45+QrQBaojngSJqDPrsil@public.gmane.org>]

This patch add cgroup files(and a member to struct mem_cgroup)
for swapcgroup.

The files to be added are:

- memory.swap_usage_in_bytes
- memory.swap_max_usage_in_bytes
- memory.swap_limit_in_bytes
- memory.swap_failcnt

The meaning of those files are the same as memory cgroup.


Signed-off-by: Daisuke Nishimura <nishimura-YQH0OdQVrdy45+QrQBaojngSJqDPrsil@public.gmane.org>

---
 init/Kconfig    |    7 +++++
 mm/memcontrol.c |   67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+), 0 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 6135d07..aabbb83 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -407,6 +407,13 @@ config CGROUP_MEM_RES_CTLR
 	  This config option also selects MM_OWNER config option, which
 	  could in turn add some fork/exit overhead.
 
+config CGROUP_SWAP_RES_CTLR
+	bool "Swap Resource Controller for Control Groups"
+	depends on CGROUP_MEM_RES_CTLR && SWAP
+	help
+	  Provides a swap resource controller that manages and limits swap usage.
+	  Implemented as a add-on to Memory Resource Controller.
+
 config SYSFS_DEPRECATED
 	bool
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a96577f..a837215 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -141,6 +141,12 @@ struct mem_cgroup {
 	 * statistics.
 	 */
 	struct mem_cgroup_stat stat;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	/*
+	 * the counter to account for swap usage
+	 */
+	struct res_counter swap_res;
+#endif
 };
 static struct mem_cgroup init_mem_cgroup;
 
@@ -960,6 +966,39 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
 	return 0;
 }
 
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+static u64 swap_cgroup_read(struct cgroup *cont, struct cftype *cft)
+{
+	return res_counter_read_u64(&mem_cgroup_from_cont(cont)->swap_res,
+				    cft->private);
+}
+
+static ssize_t swap_cgroup_write(struct cgroup *cont, struct cftype *cft,
+				struct file *file, const char __user *userbuf,
+				size_t nbytes, loff_t *ppos)
+{
+	return res_counter_write(&mem_cgroup_from_cont(cont)->swap_res,
+				cft->private, userbuf, nbytes, ppos,
+				mem_cgroup_write_strategy);
+}
+
+static int swap_cgroup_reset(struct cgroup *cont, unsigned int event)
+{
+	struct mem_cgroup *mem;
+
+	mem = mem_cgroup_from_cont(cont);
+	switch (event) {
+	case RES_MAX_USAGE:
+		res_counter_reset_max(&mem->swap_res);
+		break;
+	case RES_FAILCNT:
+		res_counter_reset_failcnt(&mem->swap_res);
+		break;
+	}
+	return 0;
+}
+#endif
+
 static struct cftype mem_cgroup_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -992,6 +1031,31 @@ static struct cftype mem_cgroup_files[] = {
 		.name = "stat",
 		.read_map = mem_control_stat_show,
 	},
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	{
+		.name = "swap_usage_in_bytes",
+		.private = RES_USAGE,
+		.read_u64 = swap_cgroup_read,
+	},
+	{
+		.name = "swap_max_usage_in_bytes",
+		.private = RES_MAX_USAGE,
+		.trigger = swap_cgroup_reset,
+		.read_u64 = swap_cgroup_read,
+	},
+	{
+		.name = "swap_limit_in_bytes",
+		.private = RES_LIMIT,
+		.write = swap_cgroup_write,
+		.read_u64 = swap_cgroup_read,
+	},
+	{
+		.name = "swap_failcnt",
+		.private = RES_FAILCNT,
+		.trigger = swap_cgroup_reset,
+		.read_u64 = swap_cgroup_read,
+	},
+#endif
 };
 
 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
@@ -1069,6 +1133,9 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	}
 
 	res_counter_init(&mem->res);
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	res_counter_init(&mem->swap_res);
+#endif
 
 	for_each_node_state(node, N_POSSIBLE)
 		if (alloc_mem_cgroup_per_zone_info(mem, node))