2 * kernfs.h - pseudo filesystem decoupled from vfs locking
4 * This file is released under the GPLv2.
7 #ifndef __LINUX_KERNFS_H
8 #define __LINUX_KERNFS_H
10 #include <linux/kernel.h>
11 #include <linux/err.h>
12 #include <linux/list.h>
13 #include <linux/mutex.h>
14 #include <linux/idr.h>
15 #include <linux/lockdep.h>
16 #include <linux/rbtree.h>
17 #include <linux/atomic.h>
18 #include <linux/completion.h>
23 struct vm_area_struct;
25 struct file_system_type;
27 struct kernfs_open_node;
30 enum kernfs_node_type {
32 SYSFS_KOBJ_ATTR = 0x0002,
33 SYSFS_KOBJ_LINK = 0x0004,
36 #define SYSFS_TYPE_MASK 0x000f
37 #define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK)
38 #define SYSFS_ACTIVE_REF SYSFS_KOBJ_ATTR
39 #define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
41 enum kernfs_node_flag {
42 SYSFS_FLAG_REMOVED = 0x0010,
43 SYSFS_FLAG_NS = 0x0020,
44 SYSFS_FLAG_HAS_SEQ_SHOW = 0x0040,
45 SYSFS_FLAG_HAS_MMAP = 0x0080,
46 SYSFS_FLAG_LOCKDEP = 0x0100,
49 /* type-specific structures for kernfs_node union members */
50 struct kernfs_elem_dir {
51 unsigned long subdirs;
52 /* children rbtree starts here and goes through kn->rb */
53 struct rb_root children;
56 * The kernfs hierarchy this directory belongs to. This fits
57 * better directly in kernfs_node but is here to save space.
59 struct kernfs_root *root;
62 struct kernfs_elem_symlink {
63 struct kernfs_node *target_kn;
66 struct kernfs_elem_attr {
67 const struct kernfs_ops *ops;
68 struct kernfs_open_node *open;
73 * kernfs_node - the building block of kernfs hierarchy. Each and every
74 * kernfs node is represented by single kernfs_node. Most fields are
75 * private to kernfs and shouldn't be accessed directly by kernfs users.
77 * As long as s_count reference is held, the kernfs_node itself is
78 * accessible. Dereferencing elem or any other outer entity requires
84 #ifdef CONFIG_DEBUG_LOCK_ALLOC
85 struct lockdep_map dep_map;
87 /* the following two fields are published */
88 struct kernfs_node *parent;
94 struct completion *completion;
95 struct kernfs_node *removed_list;
98 const void *ns; /* namespace tag */
99 unsigned int hash; /* ns + name hash */
101 struct kernfs_elem_dir dir;
102 struct kernfs_elem_symlink symlink;
103 struct kernfs_elem_attr attr;
108 unsigned short flags;
111 struct kernfs_iattrs *iattr;
115 /* published fields */
116 struct kernfs_node *kn;
118 /* private fields, do not use outside kernfs proper */
122 struct kernfs_open_file {
123 /* published fields */
124 struct kernfs_node *kn;
127 /* private fields, do not use outside kernfs proper */
130 struct list_head list;
133 const struct vm_operations_struct *vm_ops;
138 * Read is handled by either seq_file or raw_read().
140 * If seq_show() is present, seq_file path is active. Other seq
141 * operations are optional and if not implemented, the behavior is
142 * equivalent to single_open(). @sf->private points to the
143 * associated kernfs_open_file.
145 * read() is bounced through kernel buffer and a read larger than
146 * PAGE_SIZE results in partial operation of PAGE_SIZE.
148 int (*seq_show)(struct seq_file *sf, void *v);
150 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
151 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
152 void (*seq_stop)(struct seq_file *sf, void *v);
154 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
158 * write() is bounced through kernel buffer and a write larger than
159 * PAGE_SIZE results in partial operation of PAGE_SIZE.
161 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
164 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
166 #ifdef CONFIG_DEBUG_LOCK_ALLOC
167 struct lock_class_key lockdep_key;
173 static inline enum kernfs_node_type sysfs_type(struct kernfs_node *kn)
175 return kn->flags & SYSFS_TYPE_MASK;
179 * kernfs_enable_ns - enable namespace under a directory
180 * @kn: directory of interest, should be empty
182 * This is to be called right after @kn is created to enable namespace
183 * under it. All children of @kn must have non-NULL namespace tags and
184 * only the ones which match the super_block's tag will be visible.
186 static inline void kernfs_enable_ns(struct kernfs_node *kn)
188 WARN_ON_ONCE(sysfs_type(kn) != SYSFS_DIR);
189 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
190 kn->flags |= SYSFS_FLAG_NS;
194 * kernfs_ns_enabled - test whether namespace is enabled
195 * @kn: the node to test
197 * Test whether namespace filtering is enabled for the children of @ns.
199 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
201 return kn->flags & SYSFS_FLAG_NS;
204 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
205 const char *name, const void *ns);
206 void kernfs_get(struct kernfs_node *kn);
207 void kernfs_put(struct kernfs_node *kn);
209 struct kernfs_root *kernfs_create_root(void *priv);
210 void kernfs_destroy_root(struct kernfs_root *root);
212 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
213 const char *name, void *priv,
215 struct kernfs_node *kernfs_create_file_ns_key(struct kernfs_node *parent,
217 umode_t mode, loff_t size,
218 const struct kernfs_ops *ops,
219 void *priv, const void *ns,
220 struct lock_class_key *key);
221 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
223 struct kernfs_node *target);
224 void kernfs_remove(struct kernfs_node *kn);
225 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
227 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
228 const char *new_name, const void *new_ns);
229 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
230 void kernfs_notify(struct kernfs_node *kn);
232 const void *kernfs_super_ns(struct super_block *sb);
233 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
234 struct kernfs_root *root, const void *ns);
235 void kernfs_kill_sb(struct super_block *sb);
237 void kernfs_init(void);
239 #else /* CONFIG_SYSFS */
241 static inline enum kernfs_node_type sysfs_type(struct kernfs_node *kn)
242 { return 0; } /* whatever */
244 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
246 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
249 static inline struct kernfs_node *
250 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
254 static inline void kernfs_get(struct kernfs_node *kn) { }
255 static inline void kernfs_put(struct kernfs_node *kn) { }
257 static inline struct kernfs_root *kernfs_create_root(void *priv)
258 { return ERR_PTR(-ENOSYS); }
260 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
262 static inline struct kernfs_node *
263 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name, void *priv,
265 { return ERR_PTR(-ENOSYS); }
267 static inline struct kernfs_node *
268 kernfs_create_file_ns_key(struct kernfs_node *parent, const char *name,
269 umode_t mode, loff_t size,
270 const struct kernfs_ops *ops, void *priv,
271 const void *ns, struct lock_class_key *key)
272 { return ERR_PTR(-ENOSYS); }
274 static inline struct kernfs_node *
275 kernfs_create_link(struct kernfs_node *parent, const char *name,
276 struct kernfs_node *target)
277 { return ERR_PTR(-ENOSYS); }
279 static inline void kernfs_remove(struct kernfs_node *kn) { }
281 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
282 const char *name, const void *ns)
285 static inline int kernfs_rename_ns(struct kernfs_node *kn,
286 struct kernfs_node *new_parent,
287 const char *new_name, const void *new_ns)
290 static inline int kernfs_setattr(struct kernfs_node *kn,
291 const struct iattr *iattr)
294 static inline void kernfs_notify(struct kernfs_node *kn) { }
296 static inline const void *kernfs_super_ns(struct super_block *sb)
299 static inline struct dentry *
300 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
301 struct kernfs_root *root, const void *ns)
302 { return ERR_PTR(-ENOSYS); }
304 static inline void kernfs_kill_sb(struct super_block *sb) { }
306 static inline void kernfs_init(void) { }
308 #endif /* CONFIG_SYSFS */
310 static inline struct kernfs_node *
311 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
313 return kernfs_find_and_get_ns(kn, name, NULL);
316 static inline struct kernfs_node *
317 kernfs_create_dir(struct kernfs_node *parent, const char *name, void *priv)
319 return kernfs_create_dir_ns(parent, name, priv, NULL);
322 static inline struct kernfs_node *
323 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
324 umode_t mode, loff_t size, const struct kernfs_ops *ops,
325 void *priv, const void *ns)
327 struct lock_class_key *key = NULL;
329 #ifdef CONFIG_DEBUG_LOCK_ALLOC
330 key = (struct lock_class_key *)&ops->lockdep_key;
332 return kernfs_create_file_ns_key(parent, name, mode, size, ops, priv,
336 static inline struct kernfs_node *
337 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
338 loff_t size, const struct kernfs_ops *ops, void *priv)
340 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
343 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
346 return kernfs_remove_by_name_ns(parent, name, NULL);
349 static inline struct dentry *
350 kernfs_mount(struct file_system_type *fs_type, int flags,
351 struct kernfs_root *root)
353 return kernfs_mount_ns(fs_type, flags, root, NULL);
356 #endif /* __LINUX_KERNFS_H */