[RFC PATCH 2/9] mm/damon/sysfs-schemes: implement fail_charge_{num,denom} files

[SeongJae Park <sj@kernel.org>]

Implement the user-space ABI for the DAMOS action failed region
quota-charge ratio setup.  For this, add two new sysfs files under the
DAMON sysfs interface for DAMOS quotas.  Names of the files are
fail_charge_num and fail_charge_denom, and work for reading and setting
the numerator and denominator of the failed regions charge ratio.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 54 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 5186966dafb35..d5bfba79f105f 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1489,6 +1489,8 @@ struct damon_sysfs_quotas {
 	unsigned long reset_interval_ms;
 	unsigned long effective_sz;	/* Effective size quota in bytes */
 	enum damos_quota_goal_tuner goal_tuner;
+	unsigned int fail_charge_num;
+	unsigned int fail_charge_denom;
 };
 
 static struct damon_sysfs_quotas *damon_sysfs_quotas_alloc(void)
@@ -1663,6 +1665,48 @@ static ssize_t goal_tuner_store(struct kobject *kobj,
 	return -EINVAL;
 }
 
+static ssize_t fail_charge_num_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_quotas *quotas = container_of(kobj,
+			struct damon_sysfs_quotas, kobj);
+
+	return sysfs_emit(buf, "%u\n", quotas->fail_charge_num);
+}
+
+static ssize_t fail_charge_num_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_quotas *quotas = container_of(kobj,
+			struct damon_sysfs_quotas, kobj);
+	int err = kstrtouint(buf, 0, &quotas->fail_charge_num);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
+static ssize_t fail_charge_denom_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_quotas *quotas = container_of(kobj,
+			struct damon_sysfs_quotas, kobj);
+
+	return sysfs_emit(buf, "%u\n", quotas->fail_charge_denom);
+}
+
+static ssize_t fail_charge_denom_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_quotas *quotas = container_of(kobj,
+			struct damon_sysfs_quotas, kobj);
+	int err = kstrtouint(buf, 0, &quotas->fail_charge_denom);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
 static void damon_sysfs_quotas_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_quotas, kobj));
@@ -1683,12 +1727,20 @@ static struct kobj_attribute damon_sysfs_quotas_effective_bytes_attr =
 static struct kobj_attribute damon_sysfs_quotas_goal_tuner_attr =
 		__ATTR_RW_MODE(goal_tuner, 0600);
 
+static struct kobj_attribute damon_sysfs_quotas_fail_charge_num_attr =
+		__ATTR_RW_MODE(fail_charge_num, 0600);
+
+static struct kobj_attribute damon_sysfs_quotas_fail_charge_denom_attr =
+		__ATTR_RW_MODE(fail_charge_denom, 0600);
+
 static struct attribute *damon_sysfs_quotas_attrs[] = {
 	&damon_sysfs_quotas_ms_attr.attr,
 	&damon_sysfs_quotas_sz_attr.attr,
 	&damon_sysfs_quotas_reset_interval_ms_attr.attr,
 	&damon_sysfs_quotas_effective_bytes_attr.attr,
 	&damon_sysfs_quotas_goal_tuner_attr.attr,
+	&damon_sysfs_quotas_fail_charge_num_attr.attr,
+	&damon_sysfs_quotas_fail_charge_denom_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_quotas);
@@ -2776,6 +2828,8 @@ static struct damos *damon_sysfs_mk_scheme(
 		.weight_nr_accesses = sysfs_weights->nr_accesses,
 		.weight_age = sysfs_weights->age,
 		.goal_tuner = sysfs_quotas->goal_tuner,
+		.fail_charge_num = sysfs_quotas->fail_charge_num,
+		.fail_charge_denom = sysfs_quotas->fail_charge_denom,
 	};
 	struct damos_watermarks wmarks = {
 		.metric = sysfs_wmarks->metric,
-- 
2.47.3