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>
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_FLAG_MASK ~KERNFS_TYPE_MASK
40 enum kernfs_node_flag {
42 KERNFS_HAS_SEQ_SHOW = 0x0040,
43 KERNFS_HAS_MMAP = 0x0080,
44 KERNFS_LOCKDEP = 0x0100,
45 KERNFS_STATIC_NAME = 0x0200,
46 KERNFS_SUICIDAL = 0x0400,
47 KERNFS_SUICIDED = 0x0800,
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;
94 const void *ns; /* namespace tag */
95 unsigned int hash; /* ns + name hash */
97 struct kernfs_elem_dir dir;
98 struct kernfs_elem_symlink symlink;
99 struct kernfs_elem_attr attr;
104 unsigned short flags;
107 struct kernfs_iattrs *iattr;
111 * kernfs_dir_ops may be specified on kernfs_create_root() to support
112 * directory manipulation syscalls. These optional callbacks are invoked
113 * on the matching syscalls and can perform any kernfs operations which
114 * don't necessarily have to be the exact operation requested.
116 struct kernfs_dir_ops {
117 int (*mkdir)(struct kernfs_node *parent, const char *name,
119 int (*rmdir)(struct kernfs_node *kn);
120 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
121 const char *new_name);
125 /* published fields */
126 struct kernfs_node *kn;
128 /* private fields, do not use outside kernfs proper */
130 struct kernfs_dir_ops *dir_ops;
131 wait_queue_head_t deactivate_waitq;
134 struct kernfs_open_file {
135 /* published fields */
136 struct kernfs_node *kn;
139 /* private fields, do not use outside kernfs proper */
142 struct list_head list;
145 const struct vm_operations_struct *vm_ops;
150 * Read is handled by either seq_file or raw_read().
152 * If seq_show() is present, seq_file path is active. Other seq
153 * operations are optional and if not implemented, the behavior is
154 * equivalent to single_open(). @sf->private points to the
155 * associated kernfs_open_file.
157 * read() is bounced through kernel buffer and a read larger than
158 * PAGE_SIZE results in partial operation of PAGE_SIZE.
160 int (*seq_show)(struct seq_file *sf, void *v);
162 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
163 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
164 void (*seq_stop)(struct seq_file *sf, void *v);
166 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
170 * write() is bounced through kernel buffer and a write larger than
171 * PAGE_SIZE results in partial operation of PAGE_SIZE.
173 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
176 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
178 #ifdef CONFIG_DEBUG_LOCK_ALLOC
179 struct lock_class_key lockdep_key;
185 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
187 return kn->flags & KERNFS_TYPE_MASK;
191 * kernfs_enable_ns - enable namespace under a directory
192 * @kn: directory of interest, should be empty
194 * This is to be called right after @kn is created to enable namespace
195 * under it. All children of @kn must have non-NULL namespace tags and
196 * only the ones which match the super_block's tag will be visible.
198 static inline void kernfs_enable_ns(struct kernfs_node *kn)
200 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
201 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
202 kn->flags |= KERNFS_NS;
206 * kernfs_ns_enabled - test whether namespace is enabled
207 * @kn: the node to test
209 * Test whether namespace filtering is enabled for the children of @ns.
211 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
213 return kn->flags & KERNFS_NS;
216 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
217 const char *name, const void *ns);
218 void kernfs_get(struct kernfs_node *kn);
219 void kernfs_put(struct kernfs_node *kn);
221 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops,
223 void kernfs_destroy_root(struct kernfs_root *root);
225 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
226 const char *name, umode_t mode,
227 void *priv, const void *ns);
228 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
230 umode_t mode, loff_t size,
231 const struct kernfs_ops *ops,
232 void *priv, const void *ns,
234 struct lock_class_key *key);
235 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
237 struct kernfs_node *target);
238 void kernfs_remove(struct kernfs_node *kn);
239 void kernfs_break_active_protection(struct kernfs_node *kn);
240 void kernfs_unbreak_active_protection(struct kernfs_node *kn);
241 bool kernfs_remove_self(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 bool kernfs_remove_self(struct kernfs_node *kn)
302 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
303 const char *name, const void *ns)
306 static inline int kernfs_rename_ns(struct kernfs_node *kn,
307 struct kernfs_node *new_parent,
308 const char *new_name, const void *new_ns)
311 static inline int kernfs_setattr(struct kernfs_node *kn,
312 const struct iattr *iattr)
315 static inline void kernfs_notify(struct kernfs_node *kn) { }
317 static inline const void *kernfs_super_ns(struct super_block *sb)
320 static inline struct dentry *
321 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
322 struct kernfs_root *root, const void *ns)
323 { return ERR_PTR(-ENOSYS); }
325 static inline void kernfs_kill_sb(struct super_block *sb) { }
327 static inline void kernfs_init(void) { }
329 #endif /* CONFIG_SYSFS */
331 static inline struct kernfs_node *
332 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
334 return kernfs_find_and_get_ns(kn, name, NULL);
337 static inline struct kernfs_node *
338 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
341 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
344 static inline struct kernfs_node *
345 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
346 umode_t mode, loff_t size, const struct kernfs_ops *ops,
347 void *priv, const void *ns)
349 struct lock_class_key *key = NULL;
351 #ifdef CONFIG_DEBUG_LOCK_ALLOC
352 key = (struct lock_class_key *)&ops->lockdep_key;
354 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
358 static inline struct kernfs_node *
359 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
360 loff_t size, const struct kernfs_ops *ops, void *priv)
362 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
365 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
368 return kernfs_remove_by_name_ns(parent, name, NULL);
371 static inline struct dentry *
372 kernfs_mount(struct file_system_type *fs_type, int flags,
373 struct kernfs_root *root)
375 return kernfs_mount_ns(fs_type, flags, root, NULL);
378 #endif /* __LINUX_KERNFS_H */