1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Simple file system for zoned block devices exposing zones as files.
  4 *
  5 * Copyright (C) 2022 Western Digital Corporation or its affiliates.
  6 */
  7#include <linux/fs.h>
  8#include <linux/seq_file.h>
  9#include <linux/blkdev.h>
 10
 11#include "zonefs.h"
 12
 13struct zonefs_sysfs_attr {
 14	struct attribute attr;
 15	ssize_t (*show)(struct zonefs_sb_info *sbi, char *buf);
 16};
 17
 18#define ZONEFS_SYSFS_ATTR_RO(name) \
 19static struct zonefs_sysfs_attr zonefs_sysfs_attr_##name = __ATTR_RO(name)
 20
 21#define ATTR_LIST(name) &zonefs_sysfs_attr_##name.attr
 22
 23static ssize_t zonefs_sysfs_attr_show(struct kobject *kobj,
 24				      struct attribute *attr, char *buf)
 25{
 26	struct zonefs_sb_info *sbi =
 27		container_of(kobj, struct zonefs_sb_info, s_kobj);
 28	struct zonefs_sysfs_attr *zonefs_attr =
 29		container_of(attr, struct zonefs_sysfs_attr, attr);
 30
 31	if (!zonefs_attr->show)
 32		return 0;
 33
 34	return zonefs_attr->show(sbi, buf);
 35}
 36
 37static ssize_t max_wro_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
 38{
 39	return sysfs_emit(buf, "%u\n", sbi->s_max_wro_seq_files);
 40}
 41ZONEFS_SYSFS_ATTR_RO(max_wro_seq_files);
 42
 43static ssize_t nr_wro_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
 44{
 45	return sysfs_emit(buf, "%d\n", atomic_read(&sbi->s_wro_seq_files));
 46}
 47ZONEFS_SYSFS_ATTR_RO(nr_wro_seq_files);
 48
 49static ssize_t max_active_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
 50{
 51	return sysfs_emit(buf, "%u\n", sbi->s_max_active_seq_files);
 52}
 53ZONEFS_SYSFS_ATTR_RO(max_active_seq_files);
 54
 55static ssize_t nr_active_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
 56{
 57	return sysfs_emit(buf, "%d\n", atomic_read(&sbi->s_active_seq_files));
 58}
 59ZONEFS_SYSFS_ATTR_RO(nr_active_seq_files);
 60
 61static struct attribute *zonefs_sysfs_attrs[] = {
 62	ATTR_LIST(max_wro_seq_files),
 63	ATTR_LIST(nr_wro_seq_files),
 64	ATTR_LIST(max_active_seq_files),
 65	ATTR_LIST(nr_active_seq_files),
 66	NULL,
 67};
 68ATTRIBUTE_GROUPS(zonefs_sysfs);
 69
 70static void zonefs_sysfs_sb_release(struct kobject *kobj)
 71{
 72	struct zonefs_sb_info *sbi =
 73		container_of(kobj, struct zonefs_sb_info, s_kobj);
 74
 75	complete(&sbi->s_kobj_unregister);
 76}
 77
 78static const struct sysfs_ops zonefs_sysfs_attr_ops = {
 79	.show	= zonefs_sysfs_attr_show,
 80};
 81
 82static const struct kobj_type zonefs_sb_ktype = {
 83	.default_groups = zonefs_sysfs_groups,
 84	.sysfs_ops	= &zonefs_sysfs_attr_ops,
 85	.release	= zonefs_sysfs_sb_release,
 86};
 87
 88static struct kobject *zonefs_sysfs_root;
 89
 90int zonefs_sysfs_register(struct super_block *sb)
 91{
 92	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
 93	int ret;
 94
 95	init_completion(&sbi->s_kobj_unregister);
 96	ret = kobject_init_and_add(&sbi->s_kobj, &zonefs_sb_ktype,
 97				   zonefs_sysfs_root, "%s", sb->s_id);
 98	if (ret) {
 99		kobject_put(&sbi->s_kobj);
100		wait_for_completion(&sbi->s_kobj_unregister);
101		return ret;
102	}
103
104	sbi->s_sysfs_registered = true;
105
106	return 0;
107}
108
109void zonefs_sysfs_unregister(struct super_block *sb)
110{
111	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
112
113	if (!sbi || !sbi->s_sysfs_registered)
114		return;
115
116	kobject_del(&sbi->s_kobj);
117	kobject_put(&sbi->s_kobj);
118	wait_for_completion(&sbi->s_kobj_unregister);
119}
120
121int __init zonefs_sysfs_init(void)
122{
123	zonefs_sysfs_root = kobject_create_and_add("zonefs", fs_kobj);
124	if (!zonefs_sysfs_root)
125		return -ENOMEM;
126
127	return 0;
128}
129
130void zonefs_sysfs_exit(void)
131{
132	kobject_put(zonefs_sysfs_root);
133	zonefs_sysfs_root = NULL;
134}