sysfs-schemes.c

// SPDX-License-Identifier: GPL-2.0
/*
 * DAMON sysfs Interface
 *
 * Copyright (c) 2022 SeongJae Park <[email protected]>
 */

#include <linux/slab.h>
#include <linux/numa.h>

#include "sysfs-common.h"

/*
 * scheme region directory
 */

struct damon_sysfs_scheme_region {
	struct kobject kobj;
	struct damon_addr_range ar;
	unsigned int nr_accesses;
	unsigned int age;
	unsigned long sz_filter_passed;
	struct list_head list;
};

static struct damon_sysfs_scheme_region *damon_sysfs_scheme_region_alloc(
		struct damon_region *region)
{
	struct damon_sysfs_scheme_region *sysfs_region = kmalloc(
			sizeof(*sysfs_region), GFP_KERNEL);

	if (!sysfs_region)
		return NULL;
	sysfs_region->kobj = (struct kobject){};
	sysfs_region->ar = region->ar;
	sysfs_region->nr_accesses = region->nr_accesses_bp / 10000;
	sysfs_region->age = region->age;
	INIT_LIST_HEAD(&sysfs_region->list);
	return sysfs_region;
}

static ssize_t start_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_scheme_region *region = container_of(kobj,
			struct damon_sysfs_scheme_region, kobj);

	return sysfs_emit(buf, "%lu\n", region->ar.start);
}

static ssize_t end_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_scheme_region *region = container_of(kobj,
			struct damon_sysfs_scheme_region, kobj);

	return sysfs_emit(buf, "%lu\n", region->ar.end);
}

static ssize_t nr_accesses_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_region *region = container_of(kobj,
			struct damon_sysfs_scheme_region, kobj);

	return sysfs_emit(buf, "%u\n", region->nr_accesses);
}

static ssize_t age_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_scheme_region *region = container_of(kobj,
			struct damon_sysfs_scheme_region, kobj);

	return sysfs_emit(buf, "%u\n", region->age);
}

static ssize_t sz_filter_passed_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_region *region = container_of(kobj,
			struct damon_sysfs_scheme_region, kobj);

	return sysfs_emit(buf, "%lu\n", region->sz_filter_passed);
}

static void damon_sysfs_scheme_region_release(struct kobject *kobj)
{
	struct damon_sysfs_scheme_region *region = container_of(kobj,
			struct damon_sysfs_scheme_region, kobj);

	list_del(&region->list);
	kfree(region);
}

static struct kobj_attribute damon_sysfs_scheme_region_start_attr =
		__ATTR_RO_MODE(start, 0400);

static struct kobj_attribute damon_sysfs_scheme_region_end_attr =
		__ATTR_RO_MODE(end, 0400);

static struct kobj_attribute damon_sysfs_scheme_region_nr_accesses_attr =
		__ATTR_RO_MODE(nr_accesses, 0400);

static struct kobj_attribute damon_sysfs_scheme_region_age_attr =
		__ATTR_RO_MODE(age, 0400);

static struct kobj_attribute damon_sysfs_scheme_region_sz_filter_passed_attr =
		__ATTR_RO_MODE(sz_filter_passed, 0400);

static struct attribute *damon_sysfs_scheme_region_attrs[] = {
	&damon_sysfs_scheme_region_start_attr.attr,
	&damon_sysfs_scheme_region_end_attr.attr,
	&damon_sysfs_scheme_region_nr_accesses_attr.attr,
	&damon_sysfs_scheme_region_age_attr.attr,
	&damon_sysfs_scheme_region_sz_filter_passed_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_scheme_region);

static const struct kobj_type damon_sysfs_scheme_region_ktype = {
	.release = damon_sysfs_scheme_region_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_scheme_region_groups,
};

/*
 * scheme regions directory
 */

struct damon_sysfs_scheme_regions {
	struct kobject kobj;
	struct list_head regions_list;
	int nr_regions;
	unsigned long total_bytes;
};

static struct damon_sysfs_scheme_regions *
damon_sysfs_scheme_regions_alloc(void)
{
	struct damon_sysfs_scheme_regions *regions = kmalloc(sizeof(*regions),
			GFP_KERNEL);

	if (!regions)
		return NULL;

	regions->kobj = (struct kobject){};
	INIT_LIST_HEAD(&regions->regions_list);
	regions->nr_regions = 0;
	regions->total_bytes = 0;
	return regions;
}

static ssize_t total_bytes_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_regions *regions = container_of(kobj,
			struct damon_sysfs_scheme_regions, kobj);

	return sysfs_emit(buf, "%lu\n", regions->total_bytes);
}

static void damon_sysfs_scheme_regions_rm_dirs(
		struct damon_sysfs_scheme_regions *regions)
{
	struct damon_sysfs_scheme_region *r, *next;

	list_for_each_entry_safe(r, next, &regions->regions_list, list) {
		/* release function deletes it from the list */
		kobject_put(&r->kobj);
		regions->nr_regions--;
	}
}

static void damon_sysfs_scheme_regions_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_scheme_regions, kobj));
}

static struct kobj_attribute damon_sysfs_scheme_regions_total_bytes_attr =
		__ATTR_RO_MODE(total_bytes, 0400);

static struct attribute *damon_sysfs_scheme_regions_attrs[] = {
	&damon_sysfs_scheme_regions_total_bytes_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_scheme_regions);

static const struct kobj_type damon_sysfs_scheme_regions_ktype = {
	.release = damon_sysfs_scheme_regions_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_scheme_regions_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 sz_ops_filter_passed;
	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 sz_ops_filter_passed_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_ops_filter_passed);
}

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_sz_ops_filter_passed_attr =
		__ATTR_RO_MODE(sz_ops_filter_passed, 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_sz_ops_filter_passed_attr.attr,
	&damon_sysfs_stats_qt_exceeds_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_stats);

static const struct kobj_type damon_sysfs_stats_ktype = {
	.release = damon_sysfs_stats_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_stats_groups,
};

/*
 * filter directory
 */

/*
 * enum damos_sysfs_filter_handle_layer - Layers handling filters of a dir.
 */
enum damos_sysfs_filter_handle_layer {
	DAMOS_SYSFS_FILTER_HANDLE_LAYER_CORE,
	DAMOS_SYSFS_FILTER_HANDLE_LAYER_OPS,
	DAMOS_SYSFS_FILTER_HANDLE_LAYER_BOTH,
};

struct damon_sysfs_scheme_filter {
	struct kobject kobj;
	enum damos_sysfs_filter_handle_layer handle_layer;
	enum damos_filter_type type;
	bool matching;
	bool allow;
	char *memcg_path;
	struct damon_addr_range addr_range;
	struct damon_size_range sz_range;
	int target_idx;
};

static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(
		enum damos_sysfs_filter_handle_layer layer)
{
	struct damon_sysfs_scheme_filter *filter;

	filter = kzalloc(sizeof(struct damon_sysfs_scheme_filter), GFP_KERNEL);
	if (filter)
		filter->handle_layer = layer;
	return filter;
}

struct damos_sysfs_filter_type_name {
	enum damos_filter_type type;
	char *name;
};

static const struct damos_sysfs_filter_type_name
damos_sysfs_filter_type_names[] = {
	{
		.type = DAMOS_FILTER_TYPE_ANON,
		.name = "anon",
	},
	{
		.type = DAMOS_FILTER_TYPE_ACTIVE,
		.name = "active",
	},
	{
		.type = DAMOS_FILTER_TYPE_MEMCG,
		.name = "memcg",
	},
	{
		.type = DAMOS_FILTER_TYPE_YOUNG,
		.name = "young",
	},
	{
		.type = DAMOS_FILTER_TYPE_HUGEPAGE_SIZE,
		.name = "hugepage_size",
	},
	{
		.type = DAMOS_FILTER_TYPE_UNMAPPED,
		.name = "unmapped",
	},
	{
		.type = DAMOS_FILTER_TYPE_ADDR,
		.name = "addr",
	},
	{
		.type = DAMOS_FILTER_TYPE_TARGET,
		.name = "target",
	},
};

static ssize_t type_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_filter_type_names); i++) {
		const struct damos_sysfs_filter_type_name *type_name;

		type_name = &damos_sysfs_filter_type_names[i];
		if (type_name->type == filter->type)
			return sysfs_emit(buf, "%s\n", type_name->name);
	}
	return -EINVAL;
}

static bool damos_sysfs_scheme_filter_valid_type(
		enum damos_sysfs_filter_handle_layer layer,
		enum damos_filter_type type)
{
	switch (layer) {
	case DAMOS_SYSFS_FILTER_HANDLE_LAYER_BOTH:
		return true;
	case DAMOS_SYSFS_FILTER_HANDLE_LAYER_CORE:
		return !damos_filter_for_ops(type);
	case DAMOS_SYSFS_FILTER_HANDLE_LAYER_OPS:
		return damos_filter_for_ops(type);
	default:
		break;
	}
	return false;
}

static ssize_t type_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	ssize_t ret = -EINVAL;
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_filter_type_names); i++) {
		const struct damos_sysfs_filter_type_name *type_name;

		type_name = &damos_sysfs_filter_type_names[i];
		if (sysfs_streq(buf, type_name->name)) {
			if (!damos_sysfs_scheme_filter_valid_type(
						filter->handle_layer,
						type_name->type))
				break;
			filter->type = type_name->type;
			ret = count;
			break;
		}
	}
	return ret;
}

static ssize_t matching_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%c\n", filter->matching ? 'Y' : 'N');
}

static ssize_t matching_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	bool matching;
	int err = kstrtobool(buf, &matching);

	if (err)
		return err;

	filter->matching = matching;
	return count;
}

static ssize_t allow_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%c\n", filter->allow ? 'Y' : 'N');
}

static ssize_t allow_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	bool allow;
	int err = kstrtobool(buf, &allow);

	if (err)
		return err;

	filter->allow = allow;
	return count;
}

static ssize_t memcg_path_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%s\n",
			filter->memcg_path ? filter->memcg_path : "");
}

static ssize_t memcg_path_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	char *path = kmalloc_array(size_add(count, 1), sizeof(*path),
				   GFP_KERNEL);

	if (!path)
		return -ENOMEM;

	strscpy(path, buf, count + 1);
	kfree(filter->memcg_path);
	filter->memcg_path = path;
	return count;
}

static ssize_t addr_start_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%lu\n", filter->addr_range.start);
}

static ssize_t addr_start_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	int err = kstrtoul(buf, 0, &filter->addr_range.start);

	return err ? err : count;
}

static ssize_t addr_end_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%lu\n", filter->addr_range.end);
}

static ssize_t addr_end_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	int err = kstrtoul(buf, 0, &filter->addr_range.end);

	return err ? err : count;
}

static ssize_t min_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%lu\n", filter->sz_range.min);
}

static ssize_t min_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	int err = kstrtoul(buf, 0, &filter->sz_range.min);

	return err ? err : count;
}

static ssize_t max_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%lu\n", filter->sz_range.max);
}

static ssize_t max_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	int err = kstrtoul(buf, 0, &filter->sz_range.max);

	return err ? err : count;
}

static ssize_t damon_target_idx_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	return sysfs_emit(buf, "%d\n", filter->target_idx);
}

static ssize_t damon_target_idx_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);
	int err = kstrtoint(buf, 0, &filter->target_idx);

	return err ? err : count;
}

static void damon_sysfs_scheme_filter_release(struct kobject *kobj)
{
	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
			struct damon_sysfs_scheme_filter, kobj);

	kfree(filter->memcg_path);
	kfree(filter);
}

static struct kobj_attribute damon_sysfs_scheme_filter_type_attr =
		__ATTR_RW_MODE(type, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_matching_attr =
		__ATTR_RW_MODE(matching, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_allow_attr =
		__ATTR_RW_MODE(allow, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_memcg_path_attr =
		__ATTR_RW_MODE(memcg_path, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_addr_start_attr =
		__ATTR_RW_MODE(addr_start, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_addr_end_attr =
		__ATTR_RW_MODE(addr_end, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_min_attr =
		__ATTR_RW_MODE(min, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_max_attr =
		__ATTR_RW_MODE(max, 0600);

static struct kobj_attribute damon_sysfs_scheme_filter_damon_target_idx_attr =
		__ATTR_RW_MODE(damon_target_idx, 0600);

static struct attribute *damon_sysfs_scheme_filter_attrs[] = {
	&damon_sysfs_scheme_filter_type_attr.attr,
	&damon_sysfs_scheme_filter_matching_attr.attr,
	&damon_sysfs_scheme_filter_allow_attr.attr,
	&damon_sysfs_scheme_filter_memcg_path_attr.attr,
	&damon_sysfs_scheme_filter_addr_start_attr.attr,
	&damon_sysfs_scheme_filter_addr_end_attr.attr,
	&damon_sysfs_scheme_filter_min_attr.attr,
	&damon_sysfs_scheme_filter_max_attr.attr,
	&damon_sysfs_scheme_filter_damon_target_idx_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_scheme_filter);

static const struct kobj_type damon_sysfs_scheme_filter_ktype = {
	.release = damon_sysfs_scheme_filter_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_scheme_filter_groups,
};

/*
 * filters directory
 */

struct damon_sysfs_scheme_filters {
	struct kobject kobj;
	enum damos_sysfs_filter_handle_layer handle_layer;
	struct damon_sysfs_scheme_filter **filters_arr;
	int nr;
};

static struct damon_sysfs_scheme_filters *
damon_sysfs_scheme_filters_alloc(enum damos_sysfs_filter_handle_layer layer)
{
	struct damon_sysfs_scheme_filters *filters;

	filters = kzalloc(sizeof(struct damon_sysfs_scheme_filters), GFP_KERNEL);
	if (filters)
		filters->handle_layer = layer;
	return filters;
}

static void damon_sysfs_scheme_filters_rm_dirs(
		struct damon_sysfs_scheme_filters *filters)
{
	struct damon_sysfs_scheme_filter **filters_arr = filters->filters_arr;
	int i;

	for (i = 0; i < filters->nr; i++)
		kobject_put(&filters_arr[i]->kobj);
	filters->nr = 0;
	kfree(filters_arr);
	filters->filters_arr = NULL;
}

static int damon_sysfs_scheme_filters_add_dirs(
		struct damon_sysfs_scheme_filters *filters, int nr_filters)
{
	struct damon_sysfs_scheme_filter **filters_arr, *filter;
	int err, i;

	damon_sysfs_scheme_filters_rm_dirs(filters);
	if (!nr_filters)
		return 0;

	filters_arr = kmalloc_array(nr_filters, sizeof(*filters_arr),
			GFP_KERNEL | __GFP_NOWARN);
	if (!filters_arr)
		return -ENOMEM;
	filters->filters_arr = filters_arr;

	for (i = 0; i < nr_filters; i++) {
		filter = damon_sysfs_scheme_filter_alloc(
				filters->handle_layer);
		if (!filter) {
			damon_sysfs_scheme_filters_rm_dirs(filters);
			return -ENOMEM;
		}

		err = kobject_init_and_add(&filter->kobj,
				&damon_sysfs_scheme_filter_ktype,
				&filters->kobj, "%d", i);
		if (err) {
			kobject_put(&filter->kobj);
			damon_sysfs_scheme_filters_rm_dirs(filters);
			return err;
		}

		filters_arr[i] = filter;
		filters->nr++;
	}
	return 0;
}

static ssize_t nr_filters_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme_filters *filters = container_of(kobj,
			struct damon_sysfs_scheme_filters, kobj);

	return sysfs_emit(buf, "%d\n", filters->nr);
}

static ssize_t nr_filters_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme_filters *filters;
	int nr, err = kstrtoint(buf, 0, &nr);

	if (err)
		return err;
	if (nr < 0)
		return -EINVAL;

	filters = container_of(kobj, struct damon_sysfs_scheme_filters, kobj);

	if (!mutex_trylock(&damon_sysfs_lock))
		return -EBUSY;
	err = damon_sysfs_scheme_filters_add_dirs(filters, nr);
	mutex_unlock(&damon_sysfs_lock);
	if (err)
		return err;

	return count;
}

static void damon_sysfs_scheme_filters_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_scheme_filters, kobj));
}

static struct kobj_attribute damon_sysfs_scheme_filters_nr_attr =
		__ATTR_RW_MODE(nr_filters, 0600);

static struct attribute *damon_sysfs_scheme_filters_attrs[] = {
	&damon_sysfs_scheme_filters_nr_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_scheme_filters);

static const struct kobj_type damon_sysfs_scheme_filters_ktype = {
	.release = damon_sysfs_scheme_filters_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_scheme_filters_groups,
};

/*
 * watermarks directory
 */

struct damon_sysfs_watermarks {
	struct kobject kobj;
	enum damos_wmark_metric metric;
	unsigned long interval_us;
	unsigned long high;
	unsigned long mid;
	unsigned long low;
};

static struct damon_sysfs_watermarks *damon_sysfs_watermarks_alloc(
		enum damos_wmark_metric metric, unsigned long interval_us,
		unsigned long high, unsigned long mid, unsigned long low)
{
	struct damon_sysfs_watermarks *watermarks = kmalloc(
			sizeof(*watermarks), GFP_KERNEL);

	if (!watermarks)
		return NULL;
	watermarks->kobj = (struct kobject){};
	watermarks->metric = metric;
	watermarks->interval_us = interval_us;
	watermarks->high = high;
	watermarks->mid = mid;
	watermarks->low = low;
	return watermarks;
}

struct damos_sysfs_wmark_metric_name {
	enum damos_wmark_metric metric;
	char *name;
};

static const struct damos_sysfs_wmark_metric_name
damos_sysfs_wmark_metric_names[] = {
	{
		.metric = DAMOS_WMARK_NONE,
		.name = "none",
	},
	{
		.metric = DAMOS_WMARK_FREE_MEM_RATE,
		.name = "free_mem_rate",
	},
};

static ssize_t metric_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_wmark_metric_names); i++) {
		const struct damos_sysfs_wmark_metric_name *metric_name;

		metric_name = &damos_sysfs_wmark_metric_names[i];
		if (metric_name->metric == watermarks->metric)
			return sysfs_emit(buf, "%s\n", metric_name->name);
	}
	return -EINVAL;
}

static ssize_t metric_store(struct kobject *kobj, struct kobj_attribute *attr,
		const char *buf, size_t count)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_wmark_metric_names); i++) {
		const struct damos_sysfs_wmark_metric_name *metric_name;

		metric_name = &damos_sysfs_wmark_metric_names[i];
		if (sysfs_streq(buf, metric_name->name)) {
			watermarks->metric = metric_name->metric;
			return count;
		}
	}
	return -EINVAL;
}

static ssize_t interval_us_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);

	return sysfs_emit(buf, "%lu\n", watermarks->interval_us);
}

static ssize_t interval_us_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);
	int err = kstrtoul(buf, 0, &watermarks->interval_us);

	return err ? err : count;
}

static ssize_t high_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);

	return sysfs_emit(buf, "%lu\n", watermarks->high);
}

static ssize_t high_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);
	int err = kstrtoul(buf, 0, &watermarks->high);

	return err ? err : count;
}

static ssize_t mid_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);

	return sysfs_emit(buf, "%lu\n", watermarks->mid);
}

static ssize_t mid_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);
	int err = kstrtoul(buf, 0, &watermarks->mid);

	return err ? err : count;
}

static ssize_t low_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);

	return sysfs_emit(buf, "%lu\n", watermarks->low);
}

static ssize_t low_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_watermarks *watermarks = container_of(kobj,
			struct damon_sysfs_watermarks, kobj);
	int err = kstrtoul(buf, 0, &watermarks->low);

	return err ? err : count;
}

static void damon_sysfs_watermarks_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_watermarks, kobj));
}

static struct kobj_attribute damon_sysfs_watermarks_metric_attr =
		__ATTR_RW_MODE(metric, 0600);

static struct kobj_attribute damon_sysfs_watermarks_interval_us_attr =
		__ATTR_RW_MODE(interval_us, 0600);

static struct kobj_attribute damon_sysfs_watermarks_high_attr =
		__ATTR_RW_MODE(high, 0600);

static struct kobj_attribute damon_sysfs_watermarks_mid_attr =
		__ATTR_RW_MODE(mid, 0600);

static struct kobj_attribute damon_sysfs_watermarks_low_attr =
		__ATTR_RW_MODE(low, 0600);

static struct attribute *damon_sysfs_watermarks_attrs[] = {
	&damon_sysfs_watermarks_metric_attr.attr,
	&damon_sysfs_watermarks_interval_us_attr.attr,
	&damon_sysfs_watermarks_high_attr.attr,
	&damon_sysfs_watermarks_mid_attr.attr,
	&damon_sysfs_watermarks_low_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_watermarks);

static const struct kobj_type damon_sysfs_watermarks_ktype = {
	.release = damon_sysfs_watermarks_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_watermarks_groups,
};

/*
 * quota goal directory
 */

struct damos_sysfs_quota_goal {
	struct kobject kobj;
	enum damos_quota_goal_metric metric;
	unsigned long target_value;
	unsigned long current_value;
	int nid;
};

static struct damos_sysfs_quota_goal *damos_sysfs_quota_goal_alloc(void)
{
	return kzalloc(sizeof(struct damos_sysfs_quota_goal), GFP_KERNEL);
}

struct damos_sysfs_qgoal_metric_name {
	enum damos_quota_goal_metric metric;
	char *name;
};

static
struct damos_sysfs_qgoal_metric_name damos_sysfs_qgoal_metric_names[] = {
	{
		.metric = DAMOS_QUOTA_USER_INPUT,
		.name = "user_input",
	},
	{
		.metric = DAMOS_QUOTA_SOME_MEM_PSI_US,
		.name = "some_mem_psi_us",
	},
	{
		.metric = DAMOS_QUOTA_NODE_MEM_USED_BP,
		.name = "node_mem_used_bp",
	},
	{
		.metric = DAMOS_QUOTA_NODE_MEM_FREE_BP,
		.name = "node_mem_free_bp",
	},
};

static ssize_t target_metric_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj,
			struct damos_sysfs_quota_goal, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_metric_names); i++) {
		struct damos_sysfs_qgoal_metric_name *metric_name;

		metric_name = &damos_sysfs_qgoal_metric_names[i];
		if (metric_name->metric == goal->metric)
			return sysfs_emit(buf, "%s\n", metric_name->name);
	}
	return -EINVAL;
}

static ssize_t target_metric_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj,
			struct damos_sysfs_quota_goal, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_metric_names); i++) {
		struct damos_sysfs_qgoal_metric_name *metric_name;

		metric_name = &damos_sysfs_qgoal_metric_names[i];
		if (sysfs_streq(buf, metric_name->name)) {
			goal->metric = metric_name->metric;
			return count;
		}
	}
	return -EINVAL;
}

static ssize_t target_value_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
			damos_sysfs_quota_goal, kobj);

	return sysfs_emit(buf, "%lu\n", goal->target_value);
}

static ssize_t target_value_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
			damos_sysfs_quota_goal, kobj);
	int err = kstrtoul(buf, 0, &goal->target_value);

	return err ? err : count;
}

static ssize_t current_value_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
			damos_sysfs_quota_goal, kobj);

	return sysfs_emit(buf, "%lu\n", goal->current_value);
}

static ssize_t current_value_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
			damos_sysfs_quota_goal, kobj);
	int err = kstrtoul(buf, 0, &goal->current_value);

	/* feed callback should check existence of this file and read value */
	return err ? err : count;
}

static ssize_t nid_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
			damos_sysfs_quota_goal, kobj);

	/* todo: return error if the goal is not using nid */

	return sysfs_emit(buf, "%d\n", goal->nid);
}

static ssize_t nid_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
			damos_sysfs_quota_goal, kobj);
	int err = kstrtoint(buf, 0, &goal->nid);

	/* feed callback should check existence of this file and read value */
	return err ? err : count;
}

static void damos_sysfs_quota_goal_release(struct kobject *kobj)
{
	/* or, notify this release to the feed callback */
	kfree(container_of(kobj, struct damos_sysfs_quota_goal, kobj));
}

static struct kobj_attribute damos_sysfs_quota_goal_target_metric_attr =
		__ATTR_RW_MODE(target_metric, 0600);

static struct kobj_attribute damos_sysfs_quota_goal_target_value_attr =
		__ATTR_RW_MODE(target_value, 0600);

static struct kobj_attribute damos_sysfs_quota_goal_current_value_attr =
		__ATTR_RW_MODE(current_value, 0600);

static struct kobj_attribute damos_sysfs_quota_goal_nid_attr =
		__ATTR_RW_MODE(nid, 0600);

static struct attribute *damos_sysfs_quota_goal_attrs[] = {
	&damos_sysfs_quota_goal_target_metric_attr.attr,
	&damos_sysfs_quota_goal_target_value_attr.attr,
	&damos_sysfs_quota_goal_current_value_attr.attr,
	&damos_sysfs_quota_goal_nid_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damos_sysfs_quota_goal);

static const struct kobj_type damos_sysfs_quota_goal_ktype = {
	.release = damos_sysfs_quota_goal_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damos_sysfs_quota_goal_groups,
};

/*
 * quota goals directory
 */

struct damos_sysfs_quota_goals {
	struct kobject kobj;
	struct damos_sysfs_quota_goal **goals_arr;	/* counted by nr */
	int nr;
};

static struct damos_sysfs_quota_goals *damos_sysfs_quota_goals_alloc(void)
{
	return kzalloc(sizeof(struct damos_sysfs_quota_goals), GFP_KERNEL);
}

static void damos_sysfs_quota_goals_rm_dirs(
		struct damos_sysfs_quota_goals *goals)
{
	struct damos_sysfs_quota_goal **goals_arr = goals->goals_arr;
	int i;

	for (i = 0; i < goals->nr; i++)
		kobject_put(&goals_arr[i]->kobj);
	goals->nr = 0;
	kfree(goals_arr);
	goals->goals_arr = NULL;
}

static int damos_sysfs_quota_goals_add_dirs(
		struct damos_sysfs_quota_goals *goals, int nr_goals)
{
	struct damos_sysfs_quota_goal **goals_arr, *goal;
	int err, i;

	damos_sysfs_quota_goals_rm_dirs(goals);
	if (!nr_goals)
		return 0;

	goals_arr = kmalloc_array(nr_goals, sizeof(*goals_arr),
			GFP_KERNEL | __GFP_NOWARN);
	if (!goals_arr)
		return -ENOMEM;
	goals->goals_arr = goals_arr;

	for (i = 0; i < nr_goals; i++) {
		goal = damos_sysfs_quota_goal_alloc();
		if (!goal) {
			damos_sysfs_quota_goals_rm_dirs(goals);
			return -ENOMEM;
		}

		err = kobject_init_and_add(&goal->kobj,
				&damos_sysfs_quota_goal_ktype, &goals->kobj,
				"%d", i);
		if (err) {
			kobject_put(&goal->kobj);
			damos_sysfs_quota_goals_rm_dirs(goals);
			return err;
		}

		goals_arr[i] = goal;
		goals->nr++;
	}
	return 0;
}

static ssize_t nr_goals_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_quota_goals *goals = container_of(kobj,
			struct damos_sysfs_quota_goals, kobj);

	return sysfs_emit(buf, "%d\n", goals->nr);
}

static ssize_t nr_goals_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_quota_goals *goals;
	int nr, err = kstrtoint(buf, 0, &nr);

	if (err)
		return err;
	if (nr < 0)
		return -EINVAL;

	goals = container_of(kobj, struct damos_sysfs_quota_goals, kobj);

	if (!mutex_trylock(&damon_sysfs_lock))
		return -EBUSY;
	err = damos_sysfs_quota_goals_add_dirs(goals, nr);
	mutex_unlock(&damon_sysfs_lock);
	if (err)
		return err;

	return count;
}

static void damos_sysfs_quota_goals_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damos_sysfs_quota_goals, kobj));
}

static struct kobj_attribute damos_sysfs_quota_goals_nr_attr =
		__ATTR_RW_MODE(nr_goals, 0600);

static struct attribute *damos_sysfs_quota_goals_attrs[] = {
	&damos_sysfs_quota_goals_nr_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damos_sysfs_quota_goals);

static const struct kobj_type damos_sysfs_quota_goals_ktype = {
	.release = damos_sysfs_quota_goals_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damos_sysfs_quota_goals_groups,
};

/*
 * scheme/weights directory
 */

struct damon_sysfs_weights {
	struct kobject kobj;
	unsigned int sz;
	unsigned int nr_accesses;
	unsigned int age;
};

static struct damon_sysfs_weights *damon_sysfs_weights_alloc(unsigned int sz,
		unsigned int nr_accesses, unsigned int age)
{
	struct damon_sysfs_weights *weights = kmalloc(sizeof(*weights),
			GFP_KERNEL);

	if (!weights)
		return NULL;
	weights->kobj = (struct kobject){};
	weights->sz = sz;
	weights->nr_accesses = nr_accesses;
	weights->age = age;
	return weights;
}

static ssize_t sz_permil_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_weights *weights = container_of(kobj,
			struct damon_sysfs_weights, kobj);

	return sysfs_emit(buf, "%u\n", weights->sz);
}

static ssize_t sz_permil_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_weights *weights = container_of(kobj,
			struct damon_sysfs_weights, kobj);
	int err = kstrtouint(buf, 0, &weights->sz);

	return err ? err : count;
}

static ssize_t nr_accesses_permil_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_weights *weights = container_of(kobj,
			struct damon_sysfs_weights, kobj);

	return sysfs_emit(buf, "%u\n", weights->nr_accesses);
}

static ssize_t nr_accesses_permil_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_weights *weights = container_of(kobj,
			struct damon_sysfs_weights, kobj);
	int err = kstrtouint(buf, 0, &weights->nr_accesses);

	return err ? err : count;
}

static ssize_t age_permil_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_weights *weights = container_of(kobj,
			struct damon_sysfs_weights, kobj);

	return sysfs_emit(buf, "%u\n", weights->age);
}

static ssize_t age_permil_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_weights *weights = container_of(kobj,
			struct damon_sysfs_weights, kobj);
	int err = kstrtouint(buf, 0, &weights->age);

	return err ? err : count;
}

static void damon_sysfs_weights_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_weights, kobj));
}

static struct kobj_attribute damon_sysfs_weights_sz_attr =
		__ATTR_RW_MODE(sz_permil, 0600);

static struct kobj_attribute damon_sysfs_weights_nr_accesses_attr =
		__ATTR_RW_MODE(nr_accesses_permil, 0600);

static struct kobj_attribute damon_sysfs_weights_age_attr =
		__ATTR_RW_MODE(age_permil, 0600);

static struct attribute *damon_sysfs_weights_attrs[] = {
	&damon_sysfs_weights_sz_attr.attr,
	&damon_sysfs_weights_nr_accesses_attr.attr,
	&damon_sysfs_weights_age_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_weights);

static const struct kobj_type damon_sysfs_weights_ktype = {
	.release = damon_sysfs_weights_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_weights_groups,
};

/*
 * quotas directory
 */

struct damon_sysfs_quotas {
	struct kobject kobj;
	struct damon_sysfs_weights *weights;
	struct damos_sysfs_quota_goals *goals;
	unsigned long ms;
	unsigned long sz;
	unsigned long reset_interval_ms;
	unsigned long effective_sz;	/* Effective size quota in bytes */
};

static struct damon_sysfs_quotas *damon_sysfs_quotas_alloc(void)
{
	return kzalloc(sizeof(struct damon_sysfs_quotas), GFP_KERNEL);
}

static int damon_sysfs_quotas_add_dirs(struct damon_sysfs_quotas *quotas)
{
	struct damon_sysfs_weights *weights;
	struct damos_sysfs_quota_goals *goals;
	int err;

	weights = damon_sysfs_weights_alloc(0, 0, 0);
	if (!weights)
		return -ENOMEM;

	err = kobject_init_and_add(&weights->kobj, &damon_sysfs_weights_ktype,
			&quotas->kobj, "weights");
	if (err) {
		kobject_put(&weights->kobj);
		return err;
	}
	quotas->weights = weights;

	goals = damos_sysfs_quota_goals_alloc();
	if (!goals) {
		kobject_put(&weights->kobj);
		return -ENOMEM;
	}
	err = kobject_init_and_add(&goals->kobj,
			&damos_sysfs_quota_goals_ktype, &quotas->kobj,
			"goals");
	if (err) {
		kobject_put(&weights->kobj);
		kobject_put(&goals->kobj);
	} else {
		quotas->goals = goals;
	}

	return err;
}

static void damon_sysfs_quotas_rm_dirs(struct damon_sysfs_quotas *quotas)
{
	kobject_put(&quotas->weights->kobj);
	damos_sysfs_quota_goals_rm_dirs(quotas->goals);
	kobject_put(&quotas->goals->kobj);
}

static ssize_t ms_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, "%lu\n", quotas->ms);
}

static ssize_t ms_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 = kstrtoul(buf, 0, &quotas->ms);

	if (err)
		return -EINVAL;
	return count;
}

static ssize_t bytes_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, "%lu\n", quotas->sz);
}

static ssize_t bytes_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 = kstrtoul(buf, 0, &quotas->sz);

	if (err)
		return -EINVAL;
	return count;
}

static ssize_t reset_interval_ms_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, "%lu\n", quotas->reset_interval_ms);
}

static ssize_t reset_interval_ms_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 = kstrtoul(buf, 0, &quotas->reset_interval_ms);

	if (err)
		return -EINVAL;
	return count;
}

static ssize_t effective_bytes_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, "%lu\n", quotas->effective_sz);
}

static void damon_sysfs_quotas_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_quotas, kobj));
}

static struct kobj_attribute damon_sysfs_quotas_ms_attr =
		__ATTR_RW_MODE(ms, 0600);

static struct kobj_attribute damon_sysfs_quotas_sz_attr =
		__ATTR_RW_MODE(bytes, 0600);

static struct kobj_attribute damon_sysfs_quotas_reset_interval_ms_attr =
		__ATTR_RW_MODE(reset_interval_ms, 0600);

static struct kobj_attribute damon_sysfs_quotas_effective_bytes_attr =
		__ATTR_RO_MODE(effective_bytes, 0400);

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,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_quotas);

static const struct kobj_type damon_sysfs_quotas_ktype = {
	.release = damon_sysfs_quotas_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_quotas_groups,
};

/*
 * access_pattern directory
 */

struct damon_sysfs_access_pattern {
	struct kobject kobj;
	struct damon_sysfs_ul_range *sz;
	struct damon_sysfs_ul_range *nr_accesses;
	struct damon_sysfs_ul_range *age;
};

static
struct damon_sysfs_access_pattern *damon_sysfs_access_pattern_alloc(void)
{
	struct damon_sysfs_access_pattern *access_pattern =
		kmalloc(sizeof(*access_pattern), GFP_KERNEL);

	if (!access_pattern)
		return NULL;
	access_pattern->kobj = (struct kobject){};
	return access_pattern;
}

static int damon_sysfs_access_pattern_add_range_dir(
		struct damon_sysfs_access_pattern *access_pattern,
		struct damon_sysfs_ul_range **range_dir_ptr,
		char *name)
{
	struct damon_sysfs_ul_range *range = damon_sysfs_ul_range_alloc(0, 0);
	int err;

	if (!range)
		return -ENOMEM;
	err = kobject_init_and_add(&range->kobj, &damon_sysfs_ul_range_ktype,
			&access_pattern->kobj, "%s", name);
	if (err)
		kobject_put(&range->kobj);
	else
		*range_dir_ptr = range;
	return err;
}

static int damon_sysfs_access_pattern_add_dirs(
		struct damon_sysfs_access_pattern *access_pattern)
{
	int err;

	err = damon_sysfs_access_pattern_add_range_dir(access_pattern,
			&access_pattern->sz, "sz");
	if (err)
		goto put_sz_out;

	err = damon_sysfs_access_pattern_add_range_dir(access_pattern,
			&access_pattern->nr_accesses, "nr_accesses");
	if (err)
		goto put_nr_accesses_sz_out;

	err = damon_sysfs_access_pattern_add_range_dir(access_pattern,
			&access_pattern->age, "age");
	if (err)
		goto put_age_nr_accesses_sz_out;
	return 0;

put_age_nr_accesses_sz_out:
	kobject_put(&access_pattern->age->kobj);
	access_pattern->age = NULL;
put_nr_accesses_sz_out:
	kobject_put(&access_pattern->nr_accesses->kobj);
	access_pattern->nr_accesses = NULL;
put_sz_out:
	kobject_put(&access_pattern->sz->kobj);
	access_pattern->sz = NULL;
	return err;
}

static void damon_sysfs_access_pattern_rm_dirs(
		struct damon_sysfs_access_pattern *access_pattern)
{
	kobject_put(&access_pattern->sz->kobj);
	kobject_put(&access_pattern->nr_accesses->kobj);
	kobject_put(&access_pattern->age->kobj);
}

static void damon_sysfs_access_pattern_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_access_pattern, kobj));
}

static struct attribute *damon_sysfs_access_pattern_attrs[] = {
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_access_pattern);

static const struct kobj_type damon_sysfs_access_pattern_ktype = {
	.release = damon_sysfs_access_pattern_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_access_pattern_groups,
};

/*
 * dest (action destination) directory
 */

struct damos_sysfs_dest {
	struct kobject kobj;
	unsigned int id;
	unsigned int weight;
};

static struct damos_sysfs_dest *damos_sysfs_dest_alloc(void)
{
	return kzalloc(sizeof(struct damos_sysfs_dest), GFP_KERNEL);
}

static ssize_t id_show(
		struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_dest *dest = container_of(kobj,
			struct damos_sysfs_dest, kobj);

	return sysfs_emit(buf, "%u\n", dest->id);
}

static ssize_t id_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_dest *dest = container_of(kobj,
			struct damos_sysfs_dest, kobj);
	int err = kstrtouint(buf, 0, &dest->id);

	return err ? err : count;
}

static ssize_t weight_show(
		struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_dest *dest = container_of(kobj,
			struct damos_sysfs_dest, kobj);

	return sysfs_emit(buf, "%u\n", dest->weight);
}

static ssize_t weight_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_dest *dest = container_of(kobj,
			struct damos_sysfs_dest, kobj);
	int err = kstrtouint(buf, 0, &dest->weight);

	return err ? err : count;
}

static void damos_sysfs_dest_release(struct kobject *kobj)
{
	struct damos_sysfs_dest *dest = container_of(kobj,
			struct damos_sysfs_dest, kobj);
	kfree(dest);
}

static struct kobj_attribute damos_sysfs_dest_id_attr =
		__ATTR_RW_MODE(id, 0600);

static struct kobj_attribute damos_sysfs_dest_weight_attr =
		__ATTR_RW_MODE(weight, 0600);

static struct attribute *damos_sysfs_dest_attrs[] = {
	&damos_sysfs_dest_id_attr.attr,
	&damos_sysfs_dest_weight_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damos_sysfs_dest);

static const struct kobj_type damos_sysfs_dest_ktype = {
	.release = damos_sysfs_dest_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damos_sysfs_dest_groups,
};

/*
 * dests (action destinations) directory
 */

struct damos_sysfs_dests {
	struct kobject kobj;
	struct damos_sysfs_dest **dests_arr;
	int nr;
};

static struct damos_sysfs_dests *
damos_sysfs_dests_alloc(void)
{
	return kzalloc(sizeof(struct damos_sysfs_dests), GFP_KERNEL);
}

static void damos_sysfs_dests_rm_dirs(
		struct damos_sysfs_dests *dests)
{
	struct damos_sysfs_dest **dests_arr = dests->dests_arr;
	int i;

	for (i = 0; i < dests->nr; i++)
		kobject_put(&dests_arr[i]->kobj);
	dests->nr = 0;
	kfree(dests_arr);
	dests->dests_arr = NULL;
}

static int damos_sysfs_dests_add_dirs(
		struct damos_sysfs_dests *dests, int nr_dests)
{
	struct damos_sysfs_dest **dests_arr, *dest;
	int err, i;

	damos_sysfs_dests_rm_dirs(dests);
	if (!nr_dests)
		return 0;

	dests_arr = kmalloc_array(nr_dests, sizeof(*dests_arr),
			GFP_KERNEL | __GFP_NOWARN);
	if (!dests_arr)
		return -ENOMEM;
	dests->dests_arr = dests_arr;

	for (i = 0; i < nr_dests; i++) {
		dest = damos_sysfs_dest_alloc();
		if (!dest) {
			damos_sysfs_dests_rm_dirs(dests);
			return -ENOMEM;
		}

		err = kobject_init_and_add(&dest->kobj,
				&damos_sysfs_dest_ktype,
				&dests->kobj, "%d", i);
		if (err) {
			kobject_put(&dest->kobj);
			damos_sysfs_dests_rm_dirs(dests);
			return err;
		}

		dests_arr[i] = dest;
		dests->nr++;
	}
	return 0;
}

static ssize_t nr_dests_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damos_sysfs_dests *dests = container_of(kobj,
			struct damos_sysfs_dests, kobj);

	return sysfs_emit(buf, "%d\n", dests->nr);
}

static ssize_t nr_dests_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damos_sysfs_dests *dests;
	int nr, err = kstrtoint(buf, 0, &nr);

	if (err)
		return err;
	if (nr < 0)
		return -EINVAL;

	dests = container_of(kobj, struct damos_sysfs_dests, kobj);

	if (!mutex_trylock(&damon_sysfs_lock))
		return -EBUSY;
	err = damos_sysfs_dests_add_dirs(dests, nr);
	mutex_unlock(&damon_sysfs_lock);
	if (err)
		return err;

	return count;
}

static void damos_sysfs_dests_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damos_sysfs_dests, kobj));
}

static struct kobj_attribute damos_sysfs_dests_nr_attr =
		__ATTR_RW_MODE(nr_dests, 0600);

static struct attribute *damos_sysfs_dests_attrs[] = {
	&damos_sysfs_dests_nr_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damos_sysfs_dests);

static const struct kobj_type damos_sysfs_dests_ktype = {
	.release = damos_sysfs_dests_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damos_sysfs_dests_groups,
};

/*
 * scheme directory
 */

struct damon_sysfs_scheme {
	struct kobject kobj;
	enum damos_action action;
	struct damon_sysfs_access_pattern *access_pattern;
	unsigned long apply_interval_us;
	struct damon_sysfs_quotas *quotas;
	struct damon_sysfs_watermarks *watermarks;
	struct damon_sysfs_scheme_filters *core_filters;
	struct damon_sysfs_scheme_filters *ops_filters;
	struct damon_sysfs_scheme_filters *filters;
	struct damon_sysfs_stats *stats;
	struct damon_sysfs_scheme_regions *tried_regions;
	int target_nid;
	struct damos_sysfs_dests *dests;
};

struct damos_sysfs_action_name {
	enum damos_action action;
	char *name;
};

static struct damos_sysfs_action_name damos_sysfs_action_names[] = {
	{
		.action = DAMOS_WILLNEED,
		.name = "willneed",
	},
	{
		.action = DAMOS_COLD,
		.name = "cold",
	},
	{
		.action = DAMOS_PAGEOUT,
		.name = "pageout",
	},
	{
		.action = DAMOS_HUGEPAGE,
		.name = "hugepage",
	},
	{
		.action = DAMOS_NOHUGEPAGE,
		.name = "nohugepage",
	},
	{
		.action = DAMOS_LRU_PRIO,
		.name = "lru_prio",
	},
	{
		.action = DAMOS_LRU_DEPRIO,
		.name = "lru_deprio",
	},
	{
		.action = DAMOS_MIGRATE_HOT,
		.name = "migrate_hot",
	},
	{
		.action = DAMOS_MIGRATE_COLD,
		.name = "migrate_cold",
	},
	{
		.action = DAMOS_STAT,
		.name = "stat",
	},
};

static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc(
		enum damos_action action, unsigned long apply_interval_us)
{
	struct damon_sysfs_scheme *scheme = kmalloc(sizeof(*scheme),
				GFP_KERNEL);

	if (!scheme)
		return NULL;
	scheme->kobj = (struct kobject){};
	scheme->action = action;
	scheme->apply_interval_us = apply_interval_us;
	scheme->target_nid = NUMA_NO_NODE;
	return scheme;
}

static int damon_sysfs_scheme_set_access_pattern(
		struct damon_sysfs_scheme *scheme)
{
	struct damon_sysfs_access_pattern *access_pattern;
	int err;

	access_pattern = damon_sysfs_access_pattern_alloc();
	if (!access_pattern)
		return -ENOMEM;
	err = kobject_init_and_add(&access_pattern->kobj,
			&damon_sysfs_access_pattern_ktype, &scheme->kobj,
			"access_pattern");
	if (err)
		goto out;
	err = damon_sysfs_access_pattern_add_dirs(access_pattern);
	if (err)
		goto out;
	scheme->access_pattern = access_pattern;
	return 0;

out:
	kobject_put(&access_pattern->kobj);
	return err;
}

static int damos_sysfs_set_dests(struct damon_sysfs_scheme *scheme)
{
	struct damos_sysfs_dests *dests = damos_sysfs_dests_alloc();
	int err;

	if (!dests)
		return -ENOMEM;
	err = kobject_init_and_add(&dests->kobj, &damos_sysfs_dests_ktype,
			&scheme->kobj, "dests");
	if (err)
		kobject_put(&dests->kobj);
	else
		scheme->dests = dests;
	return err;
}

static int damon_sysfs_scheme_set_quotas(struct damon_sysfs_scheme *scheme)
{
	struct damon_sysfs_quotas *quotas = damon_sysfs_quotas_alloc();
	int err;

	if (!quotas)
		return -ENOMEM;
	err = kobject_init_and_add(&quotas->kobj, &damon_sysfs_quotas_ktype,
			&scheme->kobj, "quotas");
	if (err)
		goto out;
	err = damon_sysfs_quotas_add_dirs(quotas);
	if (err)
		goto out;
	scheme->quotas = quotas;
	return 0;

out:
	kobject_put(&quotas->kobj);
	return err;
}

static int damon_sysfs_scheme_set_watermarks(struct damon_sysfs_scheme *scheme)
{
	struct damon_sysfs_watermarks *watermarks =
		damon_sysfs_watermarks_alloc(DAMOS_WMARK_NONE, 0, 0, 0, 0);
	int err;

	if (!watermarks)
		return -ENOMEM;
	err = kobject_init_and_add(&watermarks->kobj,
			&damon_sysfs_watermarks_ktype, &scheme->kobj,
			"watermarks");
	if (err)
		kobject_put(&watermarks->kobj);
	else
		scheme->watermarks = watermarks;
	return err;
}

static int damon_sysfs_scheme_set_filters(struct damon_sysfs_scheme *scheme,
		enum damos_sysfs_filter_handle_layer layer, const char *name,
		struct damon_sysfs_scheme_filters **filters_ptr)
{
	struct damon_sysfs_scheme_filters *filters =
		damon_sysfs_scheme_filters_alloc(layer);
	int err;

	if (!filters)
		return -ENOMEM;
	err = kobject_init_and_add(&filters->kobj,
			&damon_sysfs_scheme_filters_ktype, &scheme->kobj,
			"%s", name);
	if (err)
		kobject_put(&filters->kobj);
	else
		*filters_ptr = filters;
	return err;
}

static int damos_sysfs_set_filter_dirs(struct damon_sysfs_scheme *scheme)
{
	int err;

	err = damon_sysfs_scheme_set_filters(scheme,
			DAMOS_SYSFS_FILTER_HANDLE_LAYER_BOTH, "filters",
			&scheme->filters);
	if (err)
		return err;
	err = damon_sysfs_scheme_set_filters(scheme,
			DAMOS_SYSFS_FILTER_HANDLE_LAYER_CORE, "core_filters",
			&scheme->core_filters);
	if (err)
		goto put_filters_out;
	err = damon_sysfs_scheme_set_filters(scheme,
			DAMOS_SYSFS_FILTER_HANDLE_LAYER_OPS, "ops_filters",
			&scheme->ops_filters);
	if (err)
		goto put_core_filters_out;
	return 0;

put_core_filters_out:
	kobject_put(&scheme->core_filters->kobj);
	scheme->core_filters = NULL;
put_filters_out:
	kobject_put(&scheme->filters->kobj);
	scheme->filters = NULL;
	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_set_tried_regions(
		struct damon_sysfs_scheme *scheme)
{
	struct damon_sysfs_scheme_regions *tried_regions =
		damon_sysfs_scheme_regions_alloc();
	int err;

	if (!tried_regions)
		return -ENOMEM;
	err = kobject_init_and_add(&tried_regions->kobj,
			&damon_sysfs_scheme_regions_ktype, &scheme->kobj,
			"tried_regions");
	if (err)
		kobject_put(&tried_regions->kobj);
	else
		scheme->tried_regions = tried_regions;
	return err;
}

static int damon_sysfs_scheme_add_dirs(struct damon_sysfs_scheme *scheme)
{
	int err;

	err = damon_sysfs_scheme_set_access_pattern(scheme);
	if (err)
		return err;
	err = damos_sysfs_set_dests(scheme);
	if (err)
		goto put_access_pattern_out;
	err = damon_sysfs_scheme_set_quotas(scheme);
	if (err)
		goto put_dests_out;
	err = damon_sysfs_scheme_set_watermarks(scheme);
	if (err)
		goto put_quotas_access_pattern_out;
	err = damos_sysfs_set_filter_dirs(scheme);
	if (err)
		goto put_watermarks_quotas_access_pattern_out;
	err = damon_sysfs_scheme_set_stats(scheme);
	if (err)
		goto put_filters_watermarks_quotas_access_pattern_out;
	err = damon_sysfs_scheme_set_tried_regions(scheme);
	if (err)
		goto put_tried_regions_out;
	return 0;

put_tried_regions_out:
	kobject_put(&scheme->tried_regions->kobj);
	scheme->tried_regions = NULL;
put_filters_watermarks_quotas_access_pattern_out:
	kobject_put(&scheme->ops_filters->kobj);
	scheme->ops_filters = NULL;
	kobject_put(&scheme->core_filters->kobj);
	scheme->core_filters = NULL;
	kobject_put(&scheme->filters->kobj);
	scheme->filters = NULL;
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;
put_dests_out:
	kobject_put(&scheme->dests->kobj);
	scheme->dests = NULL;
put_access_pattern_out:
	kobject_put(&scheme->access_pattern->kobj);
	scheme->access_pattern = NULL;
	return err;
}

static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
{
	damon_sysfs_access_pattern_rm_dirs(scheme->access_pattern);
	kobject_put(&scheme->access_pattern->kobj);
	damos_sysfs_dests_rm_dirs(scheme->dests);
	kobject_put(&scheme->dests->kobj);
	damon_sysfs_quotas_rm_dirs(scheme->quotas);
	kobject_put(&scheme->quotas->kobj);
	kobject_put(&scheme->watermarks->kobj);
	damon_sysfs_scheme_filters_rm_dirs(scheme->filters);
	kobject_put(&scheme->filters->kobj);
	damon_sysfs_scheme_filters_rm_dirs(scheme->core_filters);
	kobject_put(&scheme->core_filters->kobj);
	damon_sysfs_scheme_filters_rm_dirs(scheme->ops_filters);
	kobject_put(&scheme->ops_filters->kobj);
	kobject_put(&scheme->stats->kobj);
	damon_sysfs_scheme_regions_rm_dirs(scheme->tried_regions);
	kobject_put(&scheme->tried_regions->kobj);
}

static ssize_t action_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	struct damon_sysfs_scheme *scheme = container_of(kobj,
			struct damon_sysfs_scheme, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_action_names); i++) {
		struct damos_sysfs_action_name *action_name;

		action_name = &damos_sysfs_action_names[i];
		if (action_name->action == scheme->action)
			return sysfs_emit(buf, "%s\n", action_name->name);
	}
	return -EINVAL;
}

static ssize_t action_store(struct kobject *kobj, struct kobj_attribute *attr,
		const char *buf, size_t count)
{
	struct damon_sysfs_scheme *scheme = container_of(kobj,
			struct damon_sysfs_scheme, kobj);
	int i;

	for (i = 0; i < ARRAY_SIZE(damos_sysfs_action_names); i++) {
		struct damos_sysfs_action_name *action_name;

		action_name = &damos_sysfs_action_names[i];
		if (sysfs_streq(buf, action_name->name)) {
			scheme->action = action_name->action;
			return count;
		}
	}
	return -EINVAL;
}

static ssize_t apply_interval_us_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme *scheme = container_of(kobj,
			struct damon_sysfs_scheme, kobj);

	return sysfs_emit(buf, "%lu\n", scheme->apply_interval_us);
}

static ssize_t apply_interval_us_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme *scheme = container_of(kobj,
			struct damon_sysfs_scheme, kobj);
	int err = kstrtoul(buf, 0, &scheme->apply_interval_us);

	return err ? err : count;
}

static ssize_t target_nid_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_scheme *scheme = container_of(kobj,
			struct damon_sysfs_scheme, kobj);

	return sysfs_emit(buf, "%d\n", scheme->target_nid);
}

static ssize_t target_nid_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_scheme *scheme = container_of(kobj,
			struct damon_sysfs_scheme, kobj);
	int err = 0;

	/* TODO: error handling for target_nid range. */
	err = kstrtoint(buf, 0, &scheme->target_nid);

	return err ? err : count;
}

static void damon_sysfs_scheme_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_scheme, kobj));
}

static struct kobj_attribute damon_sysfs_scheme_action_attr =
		__ATTR_RW_MODE(action, 0600);

static struct kobj_attribute damon_sysfs_scheme_apply_interval_us_attr =
		__ATTR_RW_MODE(apply_interval_us, 0600);

static struct kobj_attribute damon_sysfs_scheme_target_nid_attr =
		__ATTR_RW_MODE(target_nid, 0600);

static struct attribute *damon_sysfs_scheme_attrs[] = {
	&damon_sysfs_scheme_action_attr.attr,
	&damon_sysfs_scheme_apply_interval_us_attr.attr,
	&damon_sysfs_scheme_target_nid_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_scheme);

static const struct kobj_type damon_sysfs_scheme_ktype = {
	.release = damon_sysfs_scheme_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_scheme_groups,
};

/*
 * schemes directory
 */

struct damon_sysfs_schemes *damon_sysfs_schemes_alloc(void)
{
	return kzalloc(sizeof(struct damon_sysfs_schemes), GFP_KERNEL);
}

void damon_sysfs_schemes_rm_dirs(struct damon_sysfs_schemes *schemes)
{
	struct damon_sysfs_scheme **schemes_arr = schemes->schemes_arr;
	int i;

	for (i = 0; i < schemes->nr; i++) {
		damon_sysfs_scheme_rm_dirs(schemes_arr[i]);
		kobject_put(&schemes_arr[i]->kobj);
	}
	schemes->nr = 0;
	kfree(schemes_arr);
	schemes->schemes_arr = NULL;
}

static int damon_sysfs_schemes_add_dirs(struct damon_sysfs_schemes *schemes,
		int nr_schemes)
{
	struct damon_sysfs_scheme **schemes_arr, *scheme;
	int err, i;

	damon_sysfs_schemes_rm_dirs(schemes);
	if (!nr_schemes)
		return 0;

	schemes_arr = kmalloc_array(nr_schemes, sizeof(*schemes_arr),
			GFP_KERNEL | __GFP_NOWARN);
	if (!schemes_arr)
		return -ENOMEM;
	schemes->schemes_arr = schemes_arr;

	for (i = 0; i < nr_schemes; i++) {
		/*
		 * apply_interval_us as 0 means same to aggregation interval
		 * (same to before-apply_interval behavior)
		 */
		scheme = damon_sysfs_scheme_alloc(DAMOS_STAT, 0);
		if (!scheme) {
			damon_sysfs_schemes_rm_dirs(schemes);
			return -ENOMEM;
		}

		err = kobject_init_and_add(&scheme->kobj,
				&damon_sysfs_scheme_ktype, &schemes->kobj,
				"%d", i);
		if (err)
			goto out;
		err = damon_sysfs_scheme_add_dirs(scheme);
		if (err)
			goto out;

		schemes_arr[i] = scheme;
		schemes->nr++;
	}
	return 0;

out:
	damon_sysfs_schemes_rm_dirs(schemes);
	kobject_put(&scheme->kobj);
	return err;
}

static ssize_t nr_schemes_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	struct damon_sysfs_schemes *schemes = container_of(kobj,
			struct damon_sysfs_schemes, kobj);

	return sysfs_emit(buf, "%d\n", schemes->nr);
}

static ssize_t nr_schemes_store(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf, size_t count)
{
	struct damon_sysfs_schemes *schemes;
	int nr, err = kstrtoint(buf, 0, &nr);

	if (err)
		return err;
	if (nr < 0)
		return -EINVAL;

	schemes = container_of(kobj, struct damon_sysfs_schemes, kobj);

	if (!mutex_trylock(&damon_sysfs_lock))
		return -EBUSY;
	err = damon_sysfs_schemes_add_dirs(schemes, nr);
	mutex_unlock(&damon_sysfs_lock);
	if (err)
		return err;
	return count;
}

static void damon_sysfs_schemes_release(struct kobject *kobj)
{
	kfree(container_of(kobj, struct damon_sysfs_schemes, kobj));
}

static struct kobj_attribute damon_sysfs_schemes_nr_attr =
		__ATTR_RW_MODE(nr_schemes, 0600);

static struct attribute *damon_sysfs_schemes_attrs[] = {
	&damon_sysfs_schemes_nr_attr.attr,
	NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_schemes);

const struct kobj_type damon_sysfs_schemes_ktype = {
	.release = damon_sysfs_schemes_release,
	.sysfs_ops = &kobj_sysfs_ops,
	.default_groups = damon_sysfs_schemes_groups,
};

static bool damon_sysfs_memcg_path_eq(struct mem_cgroup *memcg,
		char *memcg_path_buf, char *path)
{
#ifdef CONFIG_MEMCG
	cgroup_path(memcg->css.cgroup, memcg_path_buf, PATH_MAX);
	if (sysfs_streq(memcg_path_buf, path))
		return true;
#endif /* CONFIG_MEMCG */
	return false;
}

static int damon_sysfs_memcg_path_to_id(char *memcg_path, unsigned short *id)
{
	struct mem_cgroup *memcg;
	char *path;
	bool found = false;

	if (!memcg_path)
		return -EINVAL;

	path = kmalloc_array(PATH_MAX, sizeof(*path), GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	for (memcg = mem_cgroup_iter(NULL, NULL, NULL); memcg;
			memcg = mem_cgroup_iter(NULL, memcg, NULL)) {
		/* skip removed memcg */
		if (!mem_cgroup_id(memcg))
			continue;
		if (damon_sysfs_memcg_path_eq(memcg, path, memcg_path)) {
			*id = mem_cgroup_id(memcg);
			found = true;
			break;
		}
	}

	kfree(path);
	return found ? 0 : -EINVAL;
}

static int damon_sysfs_add_scheme_filters(struct damos *scheme,
		struct damon_sysfs_scheme_filters *sysfs_filters)
{
	int i;

	for (i = 0; i < sysfs_filters->nr; i++) {
		struct damon_sysfs_scheme_filter *sysfs_filter =
			sysfs_filters->filters_arr[i];
		struct damos_filter *filter =
			damos_new_filter(sysfs_filter->type,
					sysfs_filter->matching,
					sysfs_filter->allow);
		int err;

		if (!filter)
			return -ENOMEM;
		if (filter->type == DAMOS_FILTER_TYPE_MEMCG) {
			err = damon_sysfs_memcg_path_to_id(
					sysfs_filter->memcg_path,
					&filter->memcg_id);
			if (err) {
				damos_destroy_filter(filter);
				return err;
			}
		} else if (filter->type == DAMOS_FILTER_TYPE_ADDR) {
			if (sysfs_filter->addr_range.end <
					sysfs_filter->addr_range.start) {
				damos_destroy_filter(filter);
				return -EINVAL;
			}
			filter->addr_range = sysfs_filter->addr_range;
		} else if (filter->type == DAMOS_FILTER_TYPE_TARGET) {
			filter->target_idx = sysfs_filter->target_idx;
		} else if (filter->type == DAMOS_FILTER_TYPE_HUGEPAGE_SIZE) {
			if (sysfs_filter->sz_range.min >
					sysfs_filter->sz_range.max) {
				damos_destroy_filter(filter);
				return -EINVAL;
			}
			filter->sz_range = sysfs_filter->sz_range;
		}

		damos_add_filter(scheme, filter);
	}
	return 0;
}

static int damos_sysfs_add_quota_score(
		struct damos_sysfs_quota_goals *sysfs_goals,
		struct damos_quota *quota)
{
	struct damos_quota_goal *goal;
	int i;

	for (i = 0; i < sysfs_goals->nr; i++) {
		struct damos_sysfs_quota_goal *sysfs_goal =
			sysfs_goals->goals_arr[i];

		if (!sysfs_goal->target_value)
			continue;

		goal = damos_new_quota_goal(sysfs_goal->metric,
				sysfs_goal->target_value);
		if (!goal)
			return -ENOMEM;
		switch (sysfs_goal->metric) {
		case DAMOS_QUOTA_USER_INPUT:
			goal->current_value = sysfs_goal->current_value;
			break;
		case DAMOS_QUOTA_NODE_MEM_USED_BP:
		case DAMOS_QUOTA_NODE_MEM_FREE_BP:
			goal->nid = sysfs_goal->nid;
			break;
		default:
			break;
		}
		damos_add_quota_goal(quota, goal);
	}
	return 0;
}

int damos_sysfs_set_quota_scores(struct damon_sysfs_schemes *sysfs_schemes,
		struct damon_ctx *ctx)
{
	struct damos *scheme;
	struct damos_quota quota = {};
	int i = 0;

	INIT_LIST_HEAD(&quota.goals);
	damon_for_each_scheme(scheme, ctx) {
		struct damon_sysfs_scheme *sysfs_scheme;
		struct damos_quota_goal *g, *g_next;
		int err;

		/* user could have removed the scheme sysfs dir */
		if (i >= sysfs_schemes->nr)
			break;

		sysfs_scheme = sysfs_schemes->schemes_arr[i];
		err = damos_sysfs_add_quota_score(sysfs_scheme->quotas->goals,
				&quota);
		if (err) {
			damos_for_each_quota_goal_safe(g, g_next, &quota)
				damos_destroy_quota_goal(g);
			return err;
		}
		err = damos_commit_quota_goals(&scheme->quota, &quota);
		damos_for_each_quota_goal_safe(g, g_next, &quota)
			damos_destroy_quota_goal(g);
		if (err)
			return err;
		i++;
	}
	return 0;
}

void damos_sysfs_update_effective_quotas(
		struct damon_sysfs_schemes *sysfs_schemes,
		struct damon_ctx *ctx)
{
	struct damos *scheme;
	int schemes_idx = 0;

	damon_for_each_scheme(scheme, ctx) {
		struct damon_sysfs_quotas *sysfs_quotas;

		/* user could have removed the scheme sysfs dir */
		if (schemes_idx >= sysfs_schemes->nr)
			break;

		sysfs_quotas =
			sysfs_schemes->schemes_arr[schemes_idx++]->quotas;
		sysfs_quotas->effective_sz = scheme->quota.esz;
	}
}

static int damos_sysfs_add_migrate_dest(struct damos *scheme,
		struct damos_sysfs_dests *sysfs_dests)
{
	struct damos_migrate_dests *dests = &scheme->migrate_dests;
	int i;

	dests->node_id_arr = kmalloc_array(sysfs_dests->nr,
			sizeof(*dests->node_id_arr), GFP_KERNEL);
	if (!dests->node_id_arr)
		return -ENOMEM;
	dests->weight_arr = kmalloc_array(sysfs_dests->nr,
			sizeof(*dests->weight_arr), GFP_KERNEL);
	if (!dests->weight_arr)
		/* ->node_id_arr will be freed by scheme destruction */
		return -ENOMEM;
	for (i = 0; i < sysfs_dests->nr; i++) {
		dests->node_id_arr[i] = sysfs_dests->dests_arr[i]->id;
		dests->weight_arr[i] = sysfs_dests->dests_arr[i]->weight;
	}
	dests->nr_dests = sysfs_dests->nr;
	return 0;
}

static struct damos *damon_sysfs_mk_scheme(
		struct damon_sysfs_scheme *sysfs_scheme)
{
	struct damon_sysfs_access_pattern *access_pattern =
		sysfs_scheme->access_pattern;
	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
	struct damon_sysfs_watermarks *sysfs_wmarks = sysfs_scheme->watermarks;
	struct damos *scheme;
	int err;

	struct damos_access_pattern pattern = {
		.min_sz_region = access_pattern->sz->min,
		.max_sz_region = access_pattern->sz->max,
		.min_nr_accesses = access_pattern->nr_accesses->min,
		.max_nr_accesses = access_pattern->nr_accesses->max,
		.min_age_region = access_pattern->age->min,
		.max_age_region = access_pattern->age->max,
	};
	struct damos_quota quota = {
		.ms = sysfs_quotas->ms,
		.sz = sysfs_quotas->sz,
		.reset_interval = sysfs_quotas->reset_interval_ms,
		.weight_sz = sysfs_weights->sz,
		.weight_nr_accesses = sysfs_weights->nr_accesses,
		.weight_age = sysfs_weights->age,
	};
	struct damos_watermarks wmarks = {
		.metric = sysfs_wmarks->metric,
		.interval = sysfs_wmarks->interval_us,
		.high = sysfs_wmarks->high,
		.mid = sysfs_wmarks->mid,
		.low = sysfs_wmarks->low,
	};

	scheme = damon_new_scheme(&pattern, sysfs_scheme->action,
			sysfs_scheme->apply_interval_us, &quota, &wmarks,
			sysfs_scheme->target_nid);
	if (!scheme)
		return NULL;

	err = damos_sysfs_add_quota_score(sysfs_quotas->goals, &scheme->quota);
	if (err) {
		damon_destroy_scheme(scheme);
		return NULL;
	}

	err = damon_sysfs_add_scheme_filters(scheme, sysfs_scheme->core_filters);
	if (err) {
		damon_destroy_scheme(scheme);
		return NULL;
	}
	err = damon_sysfs_add_scheme_filters(scheme, sysfs_scheme->ops_filters);
	if (err) {
		damon_destroy_scheme(scheme);
		return NULL;
	}
	err = damon_sysfs_add_scheme_filters(scheme, sysfs_scheme->filters);
	if (err) {
		damon_destroy_scheme(scheme);
		return NULL;
	}
	err = damos_sysfs_add_migrate_dest(scheme, sysfs_scheme->dests);
	if (err) {
		damon_destroy_scheme(scheme);
		return NULL;
	}
	return scheme;
}

int damon_sysfs_add_schemes(struct damon_ctx *ctx,
		struct damon_sysfs_schemes *sysfs_schemes)
{
	int i;

	for (i = 0; i < sysfs_schemes->nr; i++) {
		struct damos *scheme, *next;

		scheme = damon_sysfs_mk_scheme(sysfs_schemes->schemes_arr[i]);
		if (!scheme) {
			damon_for_each_scheme_safe(scheme, next, ctx)
				damon_destroy_scheme(scheme);
			return -ENOMEM;
		}
		damon_add_scheme(ctx, scheme);
	}
	return 0;
}

void damon_sysfs_schemes_update_stats(
		struct damon_sysfs_schemes *sysfs_schemes,
		struct damon_ctx *ctx)
{
	struct damos *scheme;
	int schemes_idx = 0;

	damon_for_each_scheme(scheme, ctx) {
		struct damon_sysfs_stats *sysfs_stats;

		/* user could have removed the scheme sysfs dir */
		if (schemes_idx >= sysfs_schemes->nr)
			break;

		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->sz_ops_filter_passed =
			scheme->stat.sz_ops_filter_passed;
		sysfs_stats->qt_exceeds = scheme->stat.qt_exceeds;
	}
}

/**
 * damos_sysfs_populate_region_dir() - Populate a schemes tried region dir.
 * @sysfs_schemes:	Schemes directory to populate regions directory.
 * @ctx:		Corresponding DAMON context.
 * @t:			DAMON target of @r.
 * @r:			DAMON region to populate the directory for.
 * @s:			Corresponding scheme.
 * @total_bytes_only:	Whether the request is for bytes update only.
 * @sz_filter_passed:	Bytes of @r that passed filters of @s.
 *
 * Called from DAMOS walk callback while holding damon_sysfs_lock.
 */
void damos_sysfs_populate_region_dir(struct damon_sysfs_schemes *sysfs_schemes,
		struct damon_ctx *ctx, struct damon_target *t,
		struct damon_region *r, struct damos *s, bool total_bytes_only,
		unsigned long sz_filter_passed)
{
	struct damos *scheme;
	struct damon_sysfs_scheme_regions *sysfs_regions;
	struct damon_sysfs_scheme_region *region;
	int schemes_idx = 0;

	damon_for_each_scheme(scheme, ctx) {
		if (scheme == s)
			break;
		schemes_idx++;
	}

	/* user could have removed the scheme sysfs dir */
	if (schemes_idx >= sysfs_schemes->nr)
		return;

	sysfs_regions = sysfs_schemes->schemes_arr[schemes_idx]->tried_regions;
	sysfs_regions->total_bytes += r->ar.end - r->ar.start;
	if (total_bytes_only)
		return;

	region = damon_sysfs_scheme_region_alloc(r);
	if (!region)
		return;
	region->sz_filter_passed = sz_filter_passed;
	list_add_tail(&region->list, &sysfs_regions->regions_list);
	sysfs_regions->nr_regions++;
	if (kobject_init_and_add(&region->kobj,
				&damon_sysfs_scheme_region_ktype,
				&sysfs_regions->kobj, "%d",
				sysfs_regions->nr_regions++)) {
		kobject_put(&region->kobj);
	}
}

int damon_sysfs_schemes_clear_regions(
		struct damon_sysfs_schemes *sysfs_schemes)
{
	int i;

	for (i = 0; i < sysfs_schemes->nr; i++) {
		struct damon_sysfs_scheme *sysfs_scheme;

		sysfs_scheme = sysfs_schemes->schemes_arr[i];
		damon_sysfs_scheme_regions_rm_dirs(
				sysfs_scheme->tried_regions);
		sysfs_scheme->tried_regions->total_bytes = 0;
	}
	return 0;
}