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/wait.h>
23 struct vm_area_struct;
25 struct file_system_type;
27 struct kernfs_open_node;
30 enum kernfs_node_type {
36 #define KERNFS_TYPE_MASK 0x000f
37 #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
39 enum kernfs_node_flag {
40 KERNFS_JUST_DEACTIVATED = 0x0010, /* used to aid lockdep annotation */
42 KERNFS_HAS_SEQ_SHOW = 0x0040,
43 KERNFS_HAS_MMAP = 0x0080,
44 KERNFS_LOCKDEP = 0x0100,
45 KERNFS_STATIC_NAME = 0x0200,
48 /* type-specific structures for kernfs_node union members */
49 struct kernfs_elem_dir {
50 unsigned long subdirs;
51 /* children rbtree starts here and goes through kn->rb */
52 struct rb_root children;
55 * The kernfs hierarchy this directory belongs to. This fits
56 * better directly in kernfs_node but is here to save space.
58 struct kernfs_root *root;
61 struct kernfs_elem_symlink {
62 struct kernfs_node *target_kn;
65 struct kernfs_elem_attr {
66 const struct kernfs_ops *ops;
67 struct kernfs_open_node *open;
72 * kernfs_node - the building block of kernfs hierarchy. Each and every
73 * kernfs node is represented by single kernfs_node. Most fields are
74 * private to kernfs and shouldn't be accessed directly by kernfs users.
76 * As long as s_count reference is held, the kernfs_node itself is
77 * accessible. Dereferencing elem or any other outer entity requires
83 #ifdef CONFIG_DEBUG_LOCK_ALLOC
84 struct lockdep_map dep_map;
86 /* the following two fields are published */
87 struct kernfs_node *parent;
92 const void *ns; /* namespace tag */
93 unsigned int hash; /* ns + name hash */
95 struct kernfs_elem_dir dir;
96 struct kernfs_elem_symlink symlink;
97 struct kernfs_elem_attr attr;
102 unsigned short flags;
105 struct kernfs_iattrs *iattr;
109 * kernfs_dir_ops may be specified on kernfs_create_root() to support
110 * directory manipulation syscalls. These optional callbacks are invoked
111 * on the matching syscalls and can perform any kernfs operations which
112 * don't necessarily have to be the exact operation requested.
114 struct kernfs_dir_ops {
115 int (*mkdir)(struct kernfs_node *parent, const char *name,
117 int (*rmdir)(struct kernfs_node *kn);
118 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
119 const char *new_name);
123 /* published fields */
124 struct kernfs_node *kn;
126 /* private fields, do not use outside kernfs proper */
128 struct kernfs_dir_ops *dir_ops;
129 wait_queue_head_t deactivate_waitq;
132 struct kernfs_open_file {
133 /* published fields */
134 struct kernfs_node *kn;
137 /* private fields, do not use outside kernfs proper */
140 struct list_head list;
143 const struct vm_operations_struct *vm_ops;
148 * Read is handled by either seq_file or raw_read().
150 * If seq_show() is present, seq_file path is active. Other seq
151 * operations are optional and if not implemented, the behavior is
152 * equivalent to single_open(). @sf->private points to the
153 * associated kernfs_open_file.
155 * read() is bounced through kernel buffer and a read larger than
156 * PAGE_SIZE results in partial operation of PAGE_SIZE.
158 int (*seq_show)(struct seq_file *sf, void *v);
160 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
161 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
162 void (*seq_stop)(struct seq_file *sf, void *v);
164 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
168 * write() is bounced through kernel buffer and a write larger than
169 * PAGE_SIZE results in partial operation of PAGE_SIZE.
171 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
174 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
176 #ifdef CONFIG_DEBUG_LOCK_ALLOC
177 struct lock_class_key lockdep_key;
183 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
185 return kn->flags & KERNFS_TYPE_MASK;
189 * kernfs_enable_ns - enable namespace under a directory
190 * @kn: directory of interest, should be empty
192 * This is to be called right after @kn is created to enable namespace
193 * under it. All children of @kn must have non-NULL namespace tags and
194 * only the ones which match the super_block's tag will be visible.
196 static inline void kernfs_enable_ns(struct kernfs_node *kn)
198 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
199 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
200 kn->flags |= KERNFS_NS;
204 * kernfs_ns_enabled - test whether namespace is enabled
205 * @kn: the node to test
207 * Test whether namespace filtering is enabled for the children of @ns.
209 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
211 return kn->flags & KERNFS_NS;
214 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
215 const char *name, const void *ns);
216 void kernfs_get(struct kernfs_node *kn);
217 void kernfs_put(struct kernfs_node *kn);
219 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops,
221 void kernfs_destroy_root(struct kernfs_root *root);
223 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
224 const char *name, umode_t mode,
225 void *priv, const void *ns);
226 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
228 umode_t mode, loff_t size,
229 const struct kernfs_ops *ops,
230 void *priv, const void *ns,
232 struct lock_class_key *key);
233 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
235 struct kernfs_node *target);
236 void kernfs_remove(struct kernfs_node *kn);
237 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
239 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
240 const char *new_name, const void *new_ns);
241 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
242 void kernfs_notify(struct kernfs_node *kn);
244 const void *kernfs_super_ns(struct super_block *sb);
245 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
246 struct kernfs_root *root, const void *ns);
247 void kernfs_kill_sb(struct super_block *sb);
249 void kernfs_init(void);
251 #else /* CONFIG_SYSFS */
253 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
254 { return 0; } /* whatever */
256 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
258 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
261 static inline struct kernfs_node *
262 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
266 static inline void kernfs_get(struct kernfs_node *kn) { }
267 static inline void kernfs_put(struct kernfs_node *kn) { }
269 static inline struct kernfs_root *
270 kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
271 { return ERR_PTR(-ENOSYS); }
273 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
275 static inline struct kernfs_node *
276 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
277 umode_t mode, void *priv, const void *ns)
278 { return ERR_PTR(-ENOSYS); }
280 static inline struct kernfs_node *
281 __kernfs_create_file(struct kernfs_node *parent, const char *name,
282 umode_t mode, loff_t size, const struct kernfs_ops *ops,
283 void *priv, const void *ns, bool name_is_static,
284 struct lock_class_key *key)
285 { return ERR_PTR(-ENOSYS); }
287 static inline struct kernfs_node *
288 kernfs_create_link(struct kernfs_node *parent, const char *name,
289 struct kernfs_node *target)
290 { return ERR_PTR(-ENOSYS); }
292 static inline void kernfs_remove(struct kernfs_node *kn) { }
294 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
295 const char *name, const void *ns)
298 static inline int kernfs_rename_ns(struct kernfs_node *kn,
299 struct kernfs_node *new_parent,
300 const char *new_name, const void *new_ns)
303 static inline int kernfs_setattr(struct kernfs_node *kn,
304 const struct iattr *iattr)
307 static inline void kernfs_notify(struct kernfs_node *kn) { }
309 static inline const void *kernfs_super_ns(struct super_block *sb)
312 static inline struct dentry *
313 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
314 struct kernfs_root *root, const void *ns)
315 { return ERR_PTR(-ENOSYS); }
317 static inline void kernfs_kill_sb(struct super_block *sb) { }
319 static inline void kernfs_init(void) { }
321 #endif /* CONFIG_SYSFS */
323 static inline struct kernfs_node *
324 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
326 return kernfs_find_and_get_ns(kn, name, NULL);
329 static inline struct kernfs_node *
330 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
333 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
336 static inline struct kernfs_node *
337 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
338 umode_t mode, loff_t size, const struct kernfs_ops *ops,
339 void *priv, const void *ns)
341 struct lock_class_key *key = NULL;
343 #ifdef CONFIG_DEBUG_LOCK_ALLOC
344 key = (struct lock_class_key *)&ops->lockdep_key;
346 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
350 static inline struct kernfs_node *
351 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
352 loff_t size, const struct kernfs_ops *ops, void *priv)
354 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
357 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
360 return kernfs_remove_by_name_ns(parent, name, NULL);
363 static inline struct dentry *
364 kernfs_mount(struct file_system_type *fs_type, int flags,
365 struct kernfs_root *root)
367 return kernfs_mount_ns(fs_type, flags, root, NULL);
370 #endif /* __LINUX_KERNFS_H */