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/*
* kernfs.h - pseudo filesystem decoupled from vfs locking
*
* This file is released under the GPLv2.
*/
#ifndef __LINUX_KERNFS_H
#define __LINUX_KERNFS_H
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/idr.h>
#include <linux/lockdep.h>
#include <linux/rbtree.h>
#include <linux/atomic.h>
#include <linux/completion.h>
struct file;
struct iattr;
struct seq_file;
struct vm_area_struct;
struct super_block;
struct file_system_type;
struct sysfs_open_dirent;
struct sysfs_inode_attrs;
enum kernfs_node_type {
SYSFS_DIR = 0x0001,
SYSFS_KOBJ_ATTR = 0x0002,
SYSFS_KOBJ_LINK = 0x0004,
};
#define SYSFS_TYPE_MASK 0x000f
#define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK)
#define SYSFS_ACTIVE_REF SYSFS_KOBJ_ATTR
#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
enum kernfs_node_flag {
SYSFS_FLAG_REMOVED = 0x0010,
SYSFS_FLAG_NS = 0x0020,
SYSFS_FLAG_HAS_SEQ_SHOW = 0x0040,
SYSFS_FLAG_HAS_MMAP = 0x0080,
SYSFS_FLAG_LOCKDEP = 0x0100,
};
/* type-specific structures for sysfs_dirent->s_* union members */
struct sysfs_elem_dir {
unsigned long subdirs;
/* children rbtree starts here and goes through sd->s_rb */
struct rb_root children;
/*
* The kernfs hierarchy this directory belongs to. This fits
* better directly in sysfs_dirent but is here to save space.
*/
struct kernfs_root *root;
};
struct sysfs_elem_symlink {
struct sysfs_dirent *target_sd;
};
struct sysfs_elem_attr {
const struct kernfs_ops *ops;
struct sysfs_open_dirent *open;
loff_t size;
};
/*
* sysfs_dirent - the building block of sysfs hierarchy. Each and every
* sysfs node is represented by single sysfs_dirent. Most fields are
* private to kernfs and shouldn't be accessed directly by kernfs users.
*
* As long as s_count reference is held, the sysfs_dirent itself is
* accessible. Dereferencing s_elem or any other outer entity
* requires s_active reference.
*/
struct sysfs_dirent {
atomic_t s_count;
atomic_t s_active;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
/* the following two fields are published */
struct sysfs_dirent *s_parent;
const char *s_name;
struct rb_node s_rb;
union {
struct completion *completion;
struct sysfs_dirent *removed_list;
} u;
const void *s_ns; /* namespace tag */
unsigned int s_hash; /* ns + name hash */
union {
struct sysfs_elem_dir s_dir;
struct sysfs_elem_symlink s_symlink;
struct sysfs_elem_attr s_attr;
};
void *priv;
unsigned short s_flags;
umode_t s_mode;
unsigned int s_ino;
struct sysfs_inode_attrs *s_iattr;
};
struct kernfs_root {
/* published fields */
struct sysfs_dirent *sd;
/* private fields, do not use outside kernfs proper */
struct ida ino_ida;
};
struct sysfs_open_file {
/* published fields */
struct sysfs_dirent *sd;
struct file *file;
/* private fields, do not use outside kernfs proper */
struct mutex mutex;
int event;
struct list_head list;
bool mmapped;
const struct vm_operations_struct *vm_ops;
};
struct kernfs_ops {
/*
* Read is handled by either seq_file or raw_read().
*
* If seq_show() is present, seq_file path is active. Other seq
* operations are optional and if not implemented, the behavior is
* equivalent to single_open(). @sf->private points to the
* associated sysfs_open_file.
*
* read() is bounced through kernel buffer and a read larger than
* PAGE_SIZE results in partial operation of PAGE_SIZE.
*/
int (*seq_show)(struct seq_file *sf, void *v);
void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
void (*seq_stop)(struct seq_file *sf, void *v);
ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes,
loff_t off);
/*
* write() is bounced through kernel buffer and a write larger than
* PAGE_SIZE results in partial operation of PAGE_SIZE.
*/
ssize_t (*write)(struct sysfs_open_file *of, char *buf, size_t bytes,
loff_t off);
int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lock_class_key lockdep_key;
#endif
};
#ifdef CONFIG_SYSFS
static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
{
return sd->s_flags & SYSFS_TYPE_MASK;
}
/**
* kernfs_enable_ns - enable namespace under a directory
* @sd: directory of interest, should be empty
*
* This is to be called right after @sd is created to enable namespace
* under it. All children of @sd must have non-NULL namespace tags and
* only the ones which match the super_block's tag will be visible.
*/
static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
{
WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
sd->s_flags |= SYSFS_FLAG_NS;
}
/**
* kernfs_ns_enabled - test whether namespace is enabled
* @sd: the node to test
*
* Test whether namespace filtering is enabled for the children of @ns.
*/
static inline bool kernfs_ns_enabled(struct sysfs_dirent *sd)
{
return sd->s_flags & SYSFS_FLAG_NS;
}
struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
const char *name, const void *ns);
void kernfs_get(struct sysfs_dirent *sd);
void kernfs_put(struct sysfs_dirent *sd);
struct kernfs_root *kernfs_create_root(void *priv);
void kernfs_destroy_root(struct kernfs_root *root);
struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
const char *name, void *priv,
const void *ns);
struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
const char *name,
umode_t mode, loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
struct lock_class_key *key);
struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
const char *name,
struct sysfs_dirent *target);
void kernfs_remove(struct sysfs_dirent *sd);
int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
const void *ns);
int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
const char *new_name, const void *new_ns);
int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
void kernfs_notify(struct sysfs_dirent *sd);
const void *kernfs_super_ns(struct super_block *sb);
struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, const void *ns);
void kernfs_kill_sb(struct super_block *sb);
void kernfs_init(void);
#else /* CONFIG_SYSFS */
static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
{ return 0; } /* whatever */
static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
static inline bool kernfs_ns_enabled(struct sysfs_dirent *sd)
{ return false; }
static inline struct sysfs_dirent *
kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
const void *ns)
{ return NULL; }
static inline void kernfs_get(struct sysfs_dirent *sd) { }
static inline void kernfs_put(struct sysfs_dirent *sd) { }
static inline struct kernfs_root *kernfs_create_root(void *priv)
{ return ERR_PTR(-ENOSYS); }
static inline void kernfs_destroy_root(struct kernfs_root *root) { }
static inline struct sysfs_dirent *
kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
const void *ns)
{ return ERR_PTR(-ENOSYS); }
static inline struct sysfs_dirent *
kernfs_create_file_ns_key(struct sysfs_dirent *parent, const char *name,
umode_t mode, loff_t size,
const struct kernfs_ops *ops, void *priv,
const void *ns, struct lock_class_key *key)
{ return ERR_PTR(-ENOSYS); }
static inline struct sysfs_dirent *
kernfs_create_link(struct sysfs_dirent *parent, const char *name,
struct sysfs_dirent *target)
{ return ERR_PTR(-ENOSYS); }
static inline void kernfs_remove(struct sysfs_dirent *sd) { }
static inline int kernfs_remove_by_name_ns(struct sysfs_dirent *parent,
const char *name, const void *ns)
{ return -ENOSYS; }
static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
struct sysfs_dirent *new_parent,
const char *new_name, const void *new_ns)
{ return -ENOSYS; }
static inline int kernfs_setattr(struct sysfs_dirent *sd,
const struct iattr *iattr)
{ return -ENOSYS; }
static inline void kernfs_notify(struct sysfs_dirent *sd) { }
static inline const void *kernfs_super_ns(struct super_block *sb)
{ return NULL; }
static inline struct dentry *
kernfs_mount_ns(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, const void *ns)
{ return ERR_PTR(-ENOSYS); }
static inline void kernfs_kill_sb(struct super_block *sb) { }
static inline void kernfs_init(void) { }
#endif /* CONFIG_SYSFS */
static inline struct sysfs_dirent *
kernfs_find_and_get(struct sysfs_dirent *sd, const char *name)
{
return kernfs_find_and_get_ns(sd, name, NULL);
}
static inline struct sysfs_dirent *
kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
{
return kernfs_create_dir_ns(parent, name, priv, NULL);
}
static inline struct sysfs_dirent *
kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
umode_t mode, loff_t size, const struct kernfs_ops *ops,
void *priv, const void *ns)
{
struct lock_class_key *key = NULL;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
key = (struct lock_class_key *)&ops->lockdep_key;
#endif
return kernfs_create_file_ns_key(parent, name, mode, size, ops, priv,
ns, key);
}
static inline struct sysfs_dirent *
kernfs_create_file(struct sysfs_dirent *parent, const char *name, umode_t mode,
loff_t size, const struct kernfs_ops *ops, void *priv)
{
return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
}
static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
const char *name)
{
return kernfs_remove_by_name_ns(parent, name, NULL);
}
static inline struct dentry *
kernfs_mount(struct file_system_type *fs_type, int flags,
struct kernfs_root *root)
{
return kernfs_mount_ns(fs_type, flags, root, NULL);
}
#endif /* __LINUX_KERNFS_H */
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