fs/zonefs/sysfs.c

   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
  13 struct 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) \
  19 static struct zonefs_sysfs_attr zonefs_sysfs_attr_##name = __ATTR_RO(name)
  20
  21 #define ATTR_LIST(name) &zonefs_sysfs_attr_##name.attr
  22
  23 static 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
  37 static 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 }
  41 ZONEFS_SYSFS_ATTR_RO(max_wro_seq_files);
  42
  43 static 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 }
  47 ZONEFS_SYSFS_ATTR_RO(nr_wro_seq_files);
  48
  49 static 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 }
  53 ZONEFS_SYSFS_ATTR_RO(max_active_seq_files);
  54
  55 static 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 }
  59 ZONEFS_SYSFS_ATTR_RO(nr_active_seq_files);
  60
  61 static 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 };
  68 ATTRIBUTE_GROUPS(zonefs_sysfs);
  69
  70 static 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
  78 static const struct sysfs_ops zonefs_sysfs_attr_ops = {
  79         .show   = zonefs_sysfs_attr_show,
  80 };
  81
  82 static 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
  88 static struct kobject *zonefs_sysfs_root;
  89
  90 int 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
 109 void 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
 121 int __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
 130 void zonefs_sysfs_exit(void)
 131 {
 132         kobject_put(zonefs_sysfs_root);
 133         zonefs_sysfs_root = NULL;
 134 }