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_REMOVED = 0x0010,
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;
93 struct kernfs_node *removed_list;
96 const void *ns; /* namespace tag */
97 unsigned int hash; /* ns + name hash */
99 struct kernfs_elem_dir dir;
100 struct kernfs_elem_symlink symlink;
101 struct kernfs_elem_attr attr;
106 unsigned short flags;
109 struct kernfs_iattrs *iattr;
113 * kernfs_dir_ops may be specified on kernfs_create_root() to support
114 * directory manipulation syscalls. These optional callbacks are invoked
115 * on the matching syscalls and can perform any kernfs operations which
116 * don't necessarily have to be the exact operation requested.
118 struct kernfs_dir_ops {
119 int (*mkdir)(struct kernfs_node *parent, const char *name,
121 int (*rmdir)(struct kernfs_node *kn);
122 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
123 const char *new_name);
127 /* published fields */
128 struct kernfs_node *kn;
130 /* private fields, do not use outside kernfs proper */
132 struct kernfs_dir_ops *dir_ops;
133 wait_queue_head_t deactivate_waitq;
136 struct kernfs_open_file {
137 /* published fields */
138 struct kernfs_node *kn;
141 /* private fields, do not use outside kernfs proper */
144 struct list_head list;
147 const struct vm_operations_struct *vm_ops;
152 * Read is handled by either seq_file or raw_read().
154 * If seq_show() is present, seq_file path is active. Other seq
155 * operations are optional and if not implemented, the behavior is
156 * equivalent to single_open(). @sf->private points to the
157 * associated kernfs_open_file.
159 * read() is bounced through kernel buffer and a read larger than
160 * PAGE_SIZE results in partial operation of PAGE_SIZE.
162 int (*seq_show)(struct seq_file *sf, void *v);
164 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
165 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
166 void (*seq_stop)(struct seq_file *sf, void *v);
168 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
172 * write() is bounced through kernel buffer and a write larger than
173 * PAGE_SIZE results in partial operation of PAGE_SIZE.
175 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
178 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
180 #ifdef CONFIG_DEBUG_LOCK_ALLOC
181 struct lock_class_key lockdep_key;
187 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
189 return kn->flags & KERNFS_TYPE_MASK;
193 * kernfs_enable_ns - enable namespace under a directory
194 * @kn: directory of interest, should be empty
196 * This is to be called right after @kn is created to enable namespace
197 * under it. All children of @kn must have non-NULL namespace tags and
198 * only the ones which match the super_block's tag will be visible.
200 static inline void kernfs_enable_ns(struct kernfs_node *kn)
202 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
203 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
204 kn->flags |= KERNFS_NS;
208 * kernfs_ns_enabled - test whether namespace is enabled
209 * @kn: the node to test
211 * Test whether namespace filtering is enabled for the children of @ns.
213 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
215 return kn->flags & KERNFS_NS;
218 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
219 const char *name, const void *ns);
220 void kernfs_get(struct kernfs_node *kn);
221 void kernfs_put(struct kernfs_node *kn);
223 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops,
225 void kernfs_destroy_root(struct kernfs_root *root);
227 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
228 const char *name, umode_t mode,
229 void *priv, const void *ns);
230 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
232 umode_t mode, loff_t size,
233 const struct kernfs_ops *ops,
234 void *priv, const void *ns,
236 struct lock_class_key *key);
237 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
239 struct kernfs_node *target);
240 void kernfs_remove(struct kernfs_node *kn);
241 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
243 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
244 const char *new_name, const void *new_ns);
245 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
246 void kernfs_notify(struct kernfs_node *kn);
248 const void *kernfs_super_ns(struct super_block *sb);
249 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
250 struct kernfs_root *root, const void *ns);
251 void kernfs_kill_sb(struct super_block *sb);
253 void kernfs_init(void);
255 #else /* CONFIG_SYSFS */
257 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
258 { return 0; } /* whatever */
260 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
262 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
265 static inline struct kernfs_node *
266 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
270 static inline void kernfs_get(struct kernfs_node *kn) { }
271 static inline void kernfs_put(struct kernfs_node *kn) { }
273 static inline struct kernfs_root *
274 kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
275 { return ERR_PTR(-ENOSYS); }
277 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
279 static inline struct kernfs_node *
280 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
281 umode_t mode, void *priv, const void *ns)
282 { return ERR_PTR(-ENOSYS); }
284 static inline struct kernfs_node *
285 __kernfs_create_file(struct kernfs_node *parent, const char *name,
286 umode_t mode, loff_t size, const struct kernfs_ops *ops,
287 void *priv, const void *ns, bool name_is_static,
288 struct lock_class_key *key)
289 { return ERR_PTR(-ENOSYS); }
291 static inline struct kernfs_node *
292 kernfs_create_link(struct kernfs_node *parent, const char *name,
293 struct kernfs_node *target)
294 { return ERR_PTR(-ENOSYS); }
296 static inline void kernfs_remove(struct kernfs_node *kn) { }
298 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
299 const char *name, const void *ns)
302 static inline int kernfs_rename_ns(struct kernfs_node *kn,
303 struct kernfs_node *new_parent,
304 const char *new_name, const void *new_ns)
307 static inline int kernfs_setattr(struct kernfs_node *kn,
308 const struct iattr *iattr)
311 static inline void kernfs_notify(struct kernfs_node *kn) { }
313 static inline const void *kernfs_super_ns(struct super_block *sb)
316 static inline struct dentry *
317 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
318 struct kernfs_root *root, const void *ns)
319 { return ERR_PTR(-ENOSYS); }
321 static inline void kernfs_kill_sb(struct super_block *sb) { }
323 static inline void kernfs_init(void) { }
325 #endif /* CONFIG_SYSFS */
327 static inline struct kernfs_node *
328 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
330 return kernfs_find_and_get_ns(kn, name, NULL);
333 static inline struct kernfs_node *
334 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
337 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
340 static inline struct kernfs_node *
341 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
342 umode_t mode, loff_t size, const struct kernfs_ops *ops,
343 void *priv, const void *ns)
345 struct lock_class_key *key = NULL;
347 #ifdef CONFIG_DEBUG_LOCK_ALLOC
348 key = (struct lock_class_key *)&ops->lockdep_key;
350 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
354 static inline struct kernfs_node *
355 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
356 loff_t size, const struct kernfs_ops *ops, void *priv)
358 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
361 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
364 return kernfs_remove_by_name_ns(parent, name, NULL);
367 static inline struct dentry *
368 kernfs_mount(struct file_system_type *fs_type, int flags,
369 struct kernfs_root *root)
371 return kernfs_mount_ns(fs_type, flags, root, NULL);
374 #endif /* __LINUX_KERNFS_H */