cgroup: Support iocost for cgroup v1

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I63YN6

---------------------------

Since iocost can only be used in cgroup v2, add it to v1 now.
Signed-off-by: NLi Nan <linan122@huawei.com>

block/blk-iocost.c

@@ -3396,6 +3396,28 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
 	return ret;
 }
 
+static struct cftype ioc_legacy_files[] = {
+	{
+		.name = "cost.weight",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = ioc_weight_show,
+		.write = ioc_weight_write,
+	},
+	{
+		.name = "cost.qos",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.seq_show = ioc_qos_show,
+		.write = ioc_qos_write,
+	},
+	{
+		.name = "cost.model",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.seq_show = ioc_cost_model_show,
+		.write = ioc_cost_model_write,
+	},
+	{}
+};
+
 static struct cftype ioc_files[] = {
 	{
 		.name = "weight",
@@ -3420,6 +3442,7 @@ static struct cftype ioc_files[] = {
 
 static struct blkcg_policy blkcg_policy_iocost = {
 	.dfl_cftypes	= ioc_files,
+	.legacy_cftypes = ioc_legacy_files,
 	.cpd_alloc_fn	= ioc_cpd_alloc,
 	.cpd_free_fn	= ioc_cpd_free,
 	.pd_alloc_fn	= ioc_pd_alloc,