[v2,10/13] mm/damon/sysfs: Support DAMOS stats

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 2e09ed36f666..32a9d21c0db5 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -113,6 +113,105 @@  static struct kobj_type damon_sysfs_ul_range_ktype = {
 	.default_groups = damon_sysfs_ul_range_groups,
 };
 
+/*
+ * schemes/stats directory
+ */
+
+struct damon_sysfs_stats {
+	struct kobject kobj;
+	unsigned long nr_tried;
+	unsigned long sz_tried;
+	unsigned long nr_applied;
+	unsigned long sz_applied;
+	unsigned long qt_exceeds;
+};
+
+static struct damon_sysfs_stats *damon_sysfs_stats_alloc(void)
+{
+	return kzalloc(sizeof(struct damon_sysfs_stats), GFP_KERNEL);
+}
+
+static ssize_t nr_tried_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct damon_sysfs_stats *stats = container_of(kobj,
+			struct damon_sysfs_stats, kobj);
+
+	return sysfs_emit(buf, "%lu\n", stats->nr_tried);
+}
+
+static ssize_t sz_tried_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct damon_sysfs_stats *stats = container_of(kobj,
+			struct damon_sysfs_stats, kobj);
+
+	return sysfs_emit(buf, "%lu\n", stats->sz_tried);
+}
+
+static ssize_t nr_applied_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_stats *stats = container_of(kobj,
+			struct damon_sysfs_stats, kobj);
+
+	return sysfs_emit(buf, "%lu\n", stats->nr_applied);
+}
+
+static ssize_t sz_applied_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_stats *stats = container_of(kobj,
+			struct damon_sysfs_stats, kobj);
+
+	return sysfs_emit(buf, "%lu\n", stats->sz_applied);
+}
+
+static ssize_t qt_exceeds_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_stats *stats = container_of(kobj,
+			struct damon_sysfs_stats, kobj);
+
+	return sysfs_emit(buf, "%lu\n", stats->qt_exceeds);
+}
+
+static void damon_sysfs_stats_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_stats, kobj));
+}
+
+static struct kobj_attribute damon_sysfs_stats_nr_tried_attr =
+		__ATTR_RO_MODE(nr_tried, 0400);
+
+static struct kobj_attribute damon_sysfs_stats_sz_tried_attr =
+		__ATTR_RO_MODE(sz_tried, 0400);
+
+static struct kobj_attribute damon_sysfs_stats_nr_applied_attr =
+		__ATTR_RO_MODE(nr_applied, 0400);
+
+static struct kobj_attribute damon_sysfs_stats_sz_applied_attr =
+		__ATTR_RO_MODE(sz_applied, 0400);
+
+static struct kobj_attribute damon_sysfs_stats_qt_exceeds_attr =
+		__ATTR_RO_MODE(qt_exceeds, 0400);
+
+static struct attribute *damon_sysfs_stats_attrs[] = {
+	&damon_sysfs_stats_nr_tried_attr.attr,
+	&damon_sysfs_stats_sz_tried_attr.attr,
+	&damon_sysfs_stats_nr_applied_attr.attr,
+	&damon_sysfs_stats_sz_applied_attr.attr,
+	&damon_sysfs_stats_qt_exceeds_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_stats);
+
+static struct kobj_type damon_sysfs_stats_ktype = {
+	.release = damon_sysfs_stats_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_stats_groups,
+};
+
 /*
  * watermarks directory
  */
@@ -653,6 +752,7 @@  struct damon_sysfs_scheme {
 	struct damon_sysfs_access_pattern *access_pattern;
 	struct damon_sysfs_quotas *quotas;
 	struct damon_sysfs_watermarks *watermarks;
+	struct damon_sysfs_stats *stats;
 };
 
 /* This should match with enum damos_action */
@@ -743,6 +843,22 @@  static int damon_sysfs_scheme_set_watermarks(struct damon_sysfs_scheme *scheme)
 	return err;
 }
 
+static int damon_sysfs_scheme_set_stats(struct damon_sysfs_scheme *scheme)
+{
+	struct damon_sysfs_stats *stats = damon_sysfs_stats_alloc();
+	int err;
+
+	if (!stats)
+		return -ENOMEM;
+	err = kobject_init_and_add(&stats->kobj, &damon_sysfs_stats_ktype,
+			&scheme->kobj, "stats");
+	if (err)
+		kobject_put(&stats->kobj);
+	else
+		scheme->stats = stats;
+	return err;
+}
+
 static int damon_sysfs_scheme_add_dirs(struct damon_sysfs_scheme *scheme)
 {
 	int err;
@@ -756,8 +872,14 @@  static int damon_sysfs_scheme_add_dirs(struct damon_sysfs_scheme *scheme)
 	err = damon_sysfs_scheme_set_watermarks(scheme);
 	if (err)
 		goto put_quotas_access_pattern_out;
+	err = damon_sysfs_scheme_set_stats(scheme);
+	if (err)
+		goto put_watermarks_quotas_access_pattern_out;
 	return 0;
 
+put_watermarks_quotas_access_pattern_out:
+	kobject_put(&scheme->watermarks->kobj);
+	scheme->watermarks = NULL;
 put_quotas_access_pattern_out:
 	kobject_put(&scheme->quotas->kobj);
 	scheme->quotas = NULL;
@@ -774,6 +896,7 @@  static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
 	damon_sysfs_quotas_rm_dirs(scheme->quotas);
 	kobject_put(&scheme->quotas->kobj);
 	kobject_put(&scheme->watermarks->kobj);
+	kobject_put(&scheme->stats->kobj);
 }
 
 static ssize_t action_show(struct kobject *kobj, struct kobj_attribute *attr,
@@ -2139,6 +2262,31 @@  static int damon_sysfs_turn_damon_off(struct damon_sysfs_kdamond *kdamond)
 	 */
 }
 
+static int damon_sysfs_update_schemes_stats(struct damon_sysfs_kdamond *kdamond)
+{
+	struct damon_ctx *ctx = kdamond->damon_ctx;
+	struct damos *scheme;
+	int schemes_idx = 0;
+
+	if (!ctx)
+		return -EINVAL;
+	mutex_lock(&ctx->kdamond_lock);
+	damon_for_each_scheme(scheme, ctx) {
+		struct damon_sysfs_schemes *sysfs_schemes;
+		struct damon_sysfs_stats *sysfs_stats;
+
+		sysfs_schemes = kdamond->contexts->contexts_arr[0]->schemes;
+		sysfs_stats = sysfs_schemes->schemes_arr[schemes_idx++]->stats;
+		sysfs_stats->nr_tried = scheme->stat.nr_tried;
+		sysfs_stats->sz_tried = scheme->stat.sz_tried;
+		sysfs_stats->nr_applied = scheme->stat.nr_applied;
+		sysfs_stats->sz_applied = scheme->stat.sz_applied;
+		sysfs_stats->qt_exceeds = scheme->stat.qt_exceeds;
+	}
+	mutex_unlock(&ctx->kdamond_lock);
+	return 0;
+}
+
 static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 		const char *buf, size_t count)
 {
@@ -2152,6 +2300,8 @@  static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 		ret = damon_sysfs_turn_damon_on(kdamond);
 	else if (sysfs_streq(buf, "off"))
 		ret = damon_sysfs_turn_damon_off(kdamond);
+	else if (sysfs_streq(buf, "update_schemes_stats"))
+		ret = damon_sysfs_update_schemes_stats(kdamond);
 	else
 		ret = -EINVAL;
 	mutex_unlock(&damon_sysfs_lock);