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 {
36 #define KERNFS_TYPE_MASK 0x000f
37 #define KERNFS_ACTIVE_REF KERNFS_FILE
38 #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
40 enum kernfs_node_flag {
41 KERNFS_REMOVED = 0x0010,
43 KERNFS_HAS_SEQ_SHOW = 0x0040,
44 KERNFS_HAS_MMAP = 0x0080,
45 KERNFS_LOCKDEP = 0x0100,
46 KERNFS_STATIC_NAME = 0x0200,
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 * kernfs_dir_ops may be specified on kernfs_create_root() to support
116 * directory manipulation syscalls. These optional callbacks are invoked
117 * on the matching syscalls and can perform any kernfs operations which
118 * don't necessarily have to be the exact operation requested.
120 struct kernfs_dir_ops {
121 int (*mkdir)(struct kernfs_node *parent, const char *name,
123 int (*rmdir)(struct kernfs_node *kn);
124 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
125 const char *new_name);
129 /* published fields */
130 struct kernfs_node *kn;
132 /* private fields, do not use outside kernfs proper */
134 struct kernfs_dir_ops *dir_ops;
137 struct kernfs_open_file {
138 /* published fields */
139 struct kernfs_node *kn;
142 /* private fields, do not use outside kernfs proper */
145 struct list_head list;
148 const struct vm_operations_struct *vm_ops;
153 * Read is handled by either seq_file or raw_read().
155 * If seq_show() is present, seq_file path is active. Other seq
156 * operations are optional and if not implemented, the behavior is
157 * equivalent to single_open(). @sf->private points to the
158 * associated kernfs_open_file.
160 * read() is bounced through kernel buffer and a read larger than
161 * PAGE_SIZE results in partial operation of PAGE_SIZE.
163 int (*seq_show)(struct seq_file *sf, void *v);
165 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
166 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
167 void (*seq_stop)(struct seq_file *sf, void *v);
169 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
173 * write() is bounced through kernel buffer and a write larger than
174 * PAGE_SIZE results in partial operation of PAGE_SIZE.
176 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
179 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
181 #ifdef CONFIG_DEBUG_LOCK_ALLOC
182 struct lock_class_key lockdep_key;
188 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
190 return kn->flags & KERNFS_TYPE_MASK;
194 * kernfs_enable_ns - enable namespace under a directory
195 * @kn: directory of interest, should be empty
197 * This is to be called right after @kn is created to enable namespace
198 * under it. All children of @kn must have non-NULL namespace tags and
199 * only the ones which match the super_block's tag will be visible.
201 static inline void kernfs_enable_ns(struct kernfs_node *kn)
203 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
204 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
205 kn->flags |= KERNFS_NS;
209 * kernfs_ns_enabled - test whether namespace is enabled
210 * @kn: the node to test
212 * Test whether namespace filtering is enabled for the children of @ns.
214 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
216 return kn->flags & KERNFS_NS;
219 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
220 const char *name, const void *ns);
221 void kernfs_get(struct kernfs_node *kn);
222 void kernfs_put(struct kernfs_node *kn);
224 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops,
226 void kernfs_destroy_root(struct kernfs_root *root);
228 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
229 const char *name, umode_t mode,
230 void *priv, const void *ns);
231 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
233 umode_t mode, loff_t size,
234 const struct kernfs_ops *ops,
235 void *priv, const void *ns,
237 struct lock_class_key *key);
238 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
240 struct kernfs_node *target);
241 void kernfs_remove(struct kernfs_node *kn);
242 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
244 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
245 const char *new_name, const void *new_ns);
246 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
247 void kernfs_notify(struct kernfs_node *kn);
249 const void *kernfs_super_ns(struct super_block *sb);
250 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
251 struct kernfs_root *root, const void *ns);
252 void kernfs_kill_sb(struct super_block *sb);
254 void kernfs_init(void);
256 #else /* CONFIG_SYSFS */
258 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
259 { return 0; } /* whatever */
261 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
263 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
266 static inline struct kernfs_node *
267 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
271 static inline void kernfs_get(struct kernfs_node *kn) { }
272 static inline void kernfs_put(struct kernfs_node *kn) { }
274 static inline struct kernfs_root *
275 kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
276 { return ERR_PTR(-ENOSYS); }
278 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
280 static inline struct kernfs_node *
281 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
282 umode_t mode, void *priv, const void *ns)
283 { return ERR_PTR(-ENOSYS); }
285 static inline struct kernfs_node *
286 __kernfs_create_file(struct kernfs_node *parent, const char *name,
287 umode_t mode, loff_t size, const struct kernfs_ops *ops,
288 void *priv, const void *ns, bool name_is_static,
289 struct lock_class_key *key)
290 { return ERR_PTR(-ENOSYS); }
292 static inline struct kernfs_node *
293 kernfs_create_link(struct kernfs_node *parent, const char *name,
294 struct kernfs_node *target)
295 { return ERR_PTR(-ENOSYS); }
297 static inline void kernfs_remove(struct kernfs_node *kn) { }
299 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
300 const char *name, const void *ns)
303 static inline int kernfs_rename_ns(struct kernfs_node *kn,
304 struct kernfs_node *new_parent,
305 const char *new_name, const void *new_ns)
308 static inline int kernfs_setattr(struct kernfs_node *kn,
309 const struct iattr *iattr)
312 static inline void kernfs_notify(struct kernfs_node *kn) { }
314 static inline const void *kernfs_super_ns(struct super_block *sb)
317 static inline struct dentry *
318 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
319 struct kernfs_root *root, const void *ns)
320 { return ERR_PTR(-ENOSYS); }
322 static inline void kernfs_kill_sb(struct super_block *sb) { }
324 static inline void kernfs_init(void) { }
326 #endif /* CONFIG_SYSFS */
328 static inline struct kernfs_node *
329 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
331 return kernfs_find_and_get_ns(kn, name, NULL);
334 static inline struct kernfs_node *
335 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
338 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
341 static inline struct kernfs_node *
342 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
343 umode_t mode, loff_t size, const struct kernfs_ops *ops,
344 void *priv, const void *ns)
346 struct lock_class_key *key = NULL;
348 #ifdef CONFIG_DEBUG_LOCK_ALLOC
349 key = (struct lock_class_key *)&ops->lockdep_key;
351 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
355 static inline struct kernfs_node *
356 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
357 loff_t size, const struct kernfs_ops *ops, void *priv)
359 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
362 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
365 return kernfs_remove_by_name_ns(parent, name, NULL);
368 static inline struct dentry *
369 kernfs_mount(struct file_system_type *fs_type, int flags,
370 struct kernfs_root *root)
372 return kernfs_mount_ns(fs_type, flags, root, NULL);
375 #endif /* __LINUX_KERNFS_H */