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 {
41 KERNFS_HAS_SEQ_SHOW = 0x0040,
42 KERNFS_HAS_MMAP = 0x0080,
43 KERNFS_LOCKDEP = 0x0100,
44 KERNFS_STATIC_NAME = 0x0200,
47 /* type-specific structures for kernfs_node union members */
48 struct kernfs_elem_dir {
49 unsigned long subdirs;
50 /* children rbtree starts here and goes through kn->rb */
51 struct rb_root children;
54 * The kernfs hierarchy this directory belongs to. This fits
55 * better directly in kernfs_node but is here to save space.
57 struct kernfs_root *root;
60 struct kernfs_elem_symlink {
61 struct kernfs_node *target_kn;
64 struct kernfs_elem_attr {
65 const struct kernfs_ops *ops;
66 struct kernfs_open_node *open;
71 * kernfs_node - the building block of kernfs hierarchy. Each and every
72 * kernfs node is represented by single kernfs_node. Most fields are
73 * private to kernfs and shouldn't be accessed directly by kernfs users.
75 * As long as s_count reference is held, the kernfs_node itself is
76 * accessible. Dereferencing elem or any other outer entity requires
82 #ifdef CONFIG_DEBUG_LOCK_ALLOC
83 struct lockdep_map dep_map;
85 /* the following two fields are published */
86 struct kernfs_node *parent;
92 struct kernfs_node *removed_list;
95 const void *ns; /* namespace tag */
96 unsigned int hash; /* ns + name hash */
98 struct kernfs_elem_dir dir;
99 struct kernfs_elem_symlink symlink;
100 struct kernfs_elem_attr attr;
105 unsigned short flags;
108 struct kernfs_iattrs *iattr;
112 * kernfs_dir_ops may be specified on kernfs_create_root() to support
113 * directory manipulation syscalls. These optional callbacks are invoked
114 * on the matching syscalls and can perform any kernfs operations which
115 * don't necessarily have to be the exact operation requested.
117 struct kernfs_dir_ops {
118 int (*mkdir)(struct kernfs_node *parent, const char *name,
120 int (*rmdir)(struct kernfs_node *kn);
121 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
122 const char *new_name);
126 /* published fields */
127 struct kernfs_node *kn;
129 /* private fields, do not use outside kernfs proper */
131 struct kernfs_dir_ops *dir_ops;
132 wait_queue_head_t deactivate_waitq;
135 struct kernfs_open_file {
136 /* published fields */
137 struct kernfs_node *kn;
140 /* private fields, do not use outside kernfs proper */
143 struct list_head list;
146 const struct vm_operations_struct *vm_ops;
151 * Read is handled by either seq_file or raw_read().
153 * If seq_show() is present, seq_file path is active. Other seq
154 * operations are optional and if not implemented, the behavior is
155 * equivalent to single_open(). @sf->private points to the
156 * associated kernfs_open_file.
158 * read() is bounced through kernel buffer and a read larger than
159 * PAGE_SIZE results in partial operation of PAGE_SIZE.
161 int (*seq_show)(struct seq_file *sf, void *v);
163 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
164 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
165 void (*seq_stop)(struct seq_file *sf, void *v);
167 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
171 * write() is bounced through kernel buffer and a write larger than
172 * PAGE_SIZE results in partial operation of PAGE_SIZE.
174 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
177 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
179 #ifdef CONFIG_DEBUG_LOCK_ALLOC
180 struct lock_class_key lockdep_key;
186 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
188 return kn->flags & KERNFS_TYPE_MASK;
192 * kernfs_enable_ns - enable namespace under a directory
193 * @kn: directory of interest, should be empty
195 * This is to be called right after @kn is created to enable namespace
196 * under it. All children of @kn must have non-NULL namespace tags and
197 * only the ones which match the super_block's tag will be visible.
199 static inline void kernfs_enable_ns(struct kernfs_node *kn)
201 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
202 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
203 kn->flags |= KERNFS_NS;
207 * kernfs_ns_enabled - test whether namespace is enabled
208 * @kn: the node to test
210 * Test whether namespace filtering is enabled for the children of @ns.
212 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
214 return kn->flags & KERNFS_NS;
217 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
218 const char *name, const void *ns);
219 void kernfs_get(struct kernfs_node *kn);
220 void kernfs_put(struct kernfs_node *kn);
222 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops,
224 void kernfs_destroy_root(struct kernfs_root *root);
226 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
227 const char *name, umode_t mode,
228 void *priv, const void *ns);
229 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
231 umode_t mode, loff_t size,
232 const struct kernfs_ops *ops,
233 void *priv, const void *ns,
235 struct lock_class_key *key);
236 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
238 struct kernfs_node *target);
239 void kernfs_remove(struct kernfs_node *kn);
240 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
242 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
243 const char *new_name, const void *new_ns);
244 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
245 void kernfs_notify(struct kernfs_node *kn);
247 const void *kernfs_super_ns(struct super_block *sb);
248 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
249 struct kernfs_root *root, const void *ns);
250 void kernfs_kill_sb(struct super_block *sb);
252 void kernfs_init(void);
254 #else /* CONFIG_SYSFS */
256 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
257 { return 0; } /* whatever */
259 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
261 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
264 static inline struct kernfs_node *
265 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
269 static inline void kernfs_get(struct kernfs_node *kn) { }
270 static inline void kernfs_put(struct kernfs_node *kn) { }
272 static inline struct kernfs_root *
273 kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
274 { return ERR_PTR(-ENOSYS); }
276 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
278 static inline struct kernfs_node *
279 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
280 umode_t mode, void *priv, const void *ns)
281 { return ERR_PTR(-ENOSYS); }
283 static inline struct kernfs_node *
284 __kernfs_create_file(struct kernfs_node *parent, const char *name,
285 umode_t mode, loff_t size, const struct kernfs_ops *ops,
286 void *priv, const void *ns, bool name_is_static,
287 struct lock_class_key *key)
288 { return ERR_PTR(-ENOSYS); }
290 static inline struct kernfs_node *
291 kernfs_create_link(struct kernfs_node *parent, const char *name,
292 struct kernfs_node *target)
293 { return ERR_PTR(-ENOSYS); }
295 static inline void kernfs_remove(struct kernfs_node *kn) { }
297 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
298 const char *name, const void *ns)
301 static inline int kernfs_rename_ns(struct kernfs_node *kn,
302 struct kernfs_node *new_parent,
303 const char *new_name, const void *new_ns)
306 static inline int kernfs_setattr(struct kernfs_node *kn,
307 const struct iattr *iattr)
310 static inline void kernfs_notify(struct kernfs_node *kn) { }
312 static inline const void *kernfs_super_ns(struct super_block *sb)
315 static inline struct dentry *
316 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
317 struct kernfs_root *root, const void *ns)
318 { return ERR_PTR(-ENOSYS); }
320 static inline void kernfs_kill_sb(struct super_block *sb) { }
322 static inline void kernfs_init(void) { }
324 #endif /* CONFIG_SYSFS */
326 static inline struct kernfs_node *
327 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
329 return kernfs_find_and_get_ns(kn, name, NULL);
332 static inline struct kernfs_node *
333 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
336 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
339 static inline struct kernfs_node *
340 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
341 umode_t mode, loff_t size, const struct kernfs_ops *ops,
342 void *priv, const void *ns)
344 struct lock_class_key *key = NULL;
346 #ifdef CONFIG_DEBUG_LOCK_ALLOC
347 key = (struct lock_class_key *)&ops->lockdep_key;
349 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
353 static inline struct kernfs_node *
354 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
355 loff_t size, const struct kernfs_ops *ops, void *priv)
357 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
360 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
363 return kernfs_remove_by_name_ns(parent, name, NULL);
366 static inline struct dentry *
367 kernfs_mount(struct file_system_type *fs_type, int flags,
368 struct kernfs_root *root)
370 return kernfs_mount_ns(fs_type, flags, root, NULL);
373 #endif /* __LINUX_KERNFS_H */