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>
24 struct vm_area_struct;
26 struct file_system_type;
28 struct kernfs_open_node;
31 enum kernfs_node_type {
37 #define KERNFS_TYPE_MASK 0x000f
38 #define KERNFS_ACTIVE_REF KERNFS_FILE
39 #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
41 enum kernfs_node_flag {
42 KERNFS_REMOVED = 0x0010,
44 KERNFS_HAS_SEQ_SHOW = 0x0040,
45 KERNFS_HAS_MMAP = 0x0080,
46 KERNFS_LOCKDEP = 0x0100,
47 KERNFS_STATIC_NAME = 0x0200,
50 /* type-specific structures for kernfs_node union members */
51 struct kernfs_elem_dir {
52 unsigned long subdirs;
53 /* children rbtree starts here and goes through kn->rb */
54 struct rb_root children;
57 * The kernfs hierarchy this directory belongs to. This fits
58 * better directly in kernfs_node but is here to save space.
60 struct kernfs_root *root;
63 struct kernfs_elem_symlink {
64 struct kernfs_node *target_kn;
67 struct kernfs_elem_attr {
68 const struct kernfs_ops *ops;
69 struct kernfs_open_node *open;
74 * kernfs_node - the building block of kernfs hierarchy. Each and every
75 * kernfs node is represented by single kernfs_node. Most fields are
76 * private to kernfs and shouldn't be accessed directly by kernfs users.
78 * As long as s_count reference is held, the kernfs_node itself is
79 * accessible. Dereferencing elem or any other outer entity requires
85 #ifdef CONFIG_DEBUG_LOCK_ALLOC
86 struct lockdep_map dep_map;
88 /* the following two fields are published */
89 struct kernfs_node *parent;
95 struct completion *completion;
96 struct kernfs_node *removed_list;
99 const void *ns; /* namespace tag */
100 unsigned int hash; /* ns + name hash */
102 struct kernfs_elem_dir dir;
103 struct kernfs_elem_symlink symlink;
104 struct kernfs_elem_attr attr;
109 unsigned short flags;
112 struct kernfs_iattrs *iattr;
116 * kernfs_dir_ops may be specified on kernfs_create_root() to support
117 * directory manipulation syscalls. These optional callbacks are invoked
118 * on the matching syscalls and can perform any kernfs operations which
119 * don't necessarily have to be the exact operation requested.
121 struct kernfs_dir_ops {
122 int (*mkdir)(struct kernfs_node *parent, const char *name,
124 int (*rmdir)(struct kernfs_node *kn);
125 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
126 const char *new_name);
130 /* published fields */
131 struct kernfs_node *kn;
133 /* private fields, do not use outside kernfs proper */
135 struct kernfs_dir_ops *dir_ops;
138 struct kernfs_open_file {
139 /* published fields */
140 struct kernfs_node *kn;
143 /* private fields, do not use outside kernfs proper */
146 struct list_head list;
149 const struct vm_operations_struct *vm_ops;
154 * Read is handled by either seq_file or raw_read().
156 * If seq_show() is present, seq_file path is active. Other seq
157 * operations are optional and if not implemented, the behavior is
158 * equivalent to single_open(). @sf->private points to the
159 * associated kernfs_open_file.
161 * read() is bounced through kernel buffer and a read larger than
162 * PAGE_SIZE results in partial operation of PAGE_SIZE.
164 int (*seq_show)(struct seq_file *sf, void *v);
166 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
167 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
168 void (*seq_stop)(struct seq_file *sf, void *v);
170 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
174 * write() is bounced through kernel buffer and a write larger than
175 * PAGE_SIZE results in partial operation of PAGE_SIZE.
177 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
180 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
182 #ifdef CONFIG_DEBUG_LOCK_ALLOC
183 struct lock_class_key lockdep_key;
189 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
191 return kn->flags & KERNFS_TYPE_MASK;
195 * kernfs_enable_ns - enable namespace under a directory
196 * @kn: directory of interest, should be empty
198 * This is to be called right after @kn is created to enable namespace
199 * under it. All children of @kn must have non-NULL namespace tags and
200 * only the ones which match the super_block's tag will be visible.
202 static inline void kernfs_enable_ns(struct kernfs_node *kn)
204 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
205 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
206 kn->flags |= KERNFS_NS;
210 * kernfs_ns_enabled - test whether namespace is enabled
211 * @kn: the node to test
213 * Test whether namespace filtering is enabled for the children of @ns.
215 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
217 return kn->flags & KERNFS_NS;
220 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
221 const char *name, const void *ns);
222 void kernfs_get(struct kernfs_node *kn);
223 void kernfs_put(struct kernfs_node *kn);
225 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops,
227 void kernfs_destroy_root(struct kernfs_root *root);
229 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
230 const char *name, umode_t mode,
231 void *priv, const void *ns);
232 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
234 umode_t mode, loff_t size,
235 const struct kernfs_ops *ops,
236 void *priv, const void *ns,
238 struct lock_class_key *key);
239 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
241 struct kernfs_node *target);
242 void kernfs_remove(struct kernfs_node *kn);
243 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
245 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
246 const char *new_name, const void *new_ns);
247 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
248 void kernfs_notify(struct kernfs_node *kn);
250 const void *kernfs_super_ns(struct super_block *sb);
251 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
252 struct kernfs_root *root, const void *ns);
253 void kernfs_kill_sb(struct super_block *sb);
255 void kernfs_init(void);
257 #else /* CONFIG_SYSFS */
259 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
260 { return 0; } /* whatever */
262 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
264 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
267 static inline struct kernfs_node *
268 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
272 static inline void kernfs_get(struct kernfs_node *kn) { }
273 static inline void kernfs_put(struct kernfs_node *kn) { }
275 static inline struct kernfs_root *
276 kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
277 { return ERR_PTR(-ENOSYS); }
279 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
281 static inline struct kernfs_node *
282 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
283 umode_t mode, void *priv, const void *ns)
284 { return ERR_PTR(-ENOSYS); }
286 static inline struct kernfs_node *
287 __kernfs_create_file(struct kernfs_node *parent, const char *name,
288 umode_t mode, loff_t size, const struct kernfs_ops *ops,
289 void *priv, const void *ns, bool name_is_static,
290 struct lock_class_key *key)
291 { return ERR_PTR(-ENOSYS); }
293 static inline struct kernfs_node *
294 kernfs_create_link(struct kernfs_node *parent, const char *name,
295 struct kernfs_node *target)
296 { return ERR_PTR(-ENOSYS); }
298 static inline void kernfs_remove(struct kernfs_node *kn) { }
300 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
301 const char *name, const void *ns)
304 static inline int kernfs_rename_ns(struct kernfs_node *kn,
305 struct kernfs_node *new_parent,
306 const char *new_name, const void *new_ns)
309 static inline int kernfs_setattr(struct kernfs_node *kn,
310 const struct iattr *iattr)
313 static inline void kernfs_notify(struct kernfs_node *kn) { }
315 static inline const void *kernfs_super_ns(struct super_block *sb)
318 static inline struct dentry *
319 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
320 struct kernfs_root *root, const void *ns)
321 { return ERR_PTR(-ENOSYS); }
323 static inline void kernfs_kill_sb(struct super_block *sb) { }
325 static inline void kernfs_init(void) { }
327 #endif /* CONFIG_SYSFS */
329 static inline struct kernfs_node *
330 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
332 return kernfs_find_and_get_ns(kn, name, NULL);
335 static inline struct kernfs_node *
336 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
339 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
342 static inline struct kernfs_node *
343 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
344 umode_t mode, loff_t size, const struct kernfs_ops *ops,
345 void *priv, const void *ns)
347 struct lock_class_key *key = NULL;
349 #ifdef CONFIG_DEBUG_LOCK_ALLOC
350 key = (struct lock_class_key *)&ops->lockdep_key;
352 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
356 static inline struct kernfs_node *
357 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
358 loff_t size, const struct kernfs_ops *ops, void *priv)
360 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
363 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
366 return kernfs_remove_by_name_ns(parent, name, NULL);
369 static inline struct dentry *
370 kernfs_mount(struct file_system_type *fs_type, int flags,
371 struct kernfs_root *root)
373 return kernfs_mount_ns(fs_type, flags, root, NULL);
376 #endif /* __LINUX_KERNFS_H */