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 {
41 KERNFS_ACTIVATED = 0x0010,
43 KERNFS_HAS_SEQ_SHOW = 0x0040,
44 KERNFS_HAS_MMAP = 0x0080,
45 KERNFS_LOCKDEP = 0x0100,
46 KERNFS_STATIC_NAME = 0x0200,
47 KERNFS_SUICIDAL = 0x0400,
48 KERNFS_SUICIDED = 0x0800,
51 /* @flags for kernfs_create_root() */
52 enum kernfs_root_flag {
53 KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001,
56 /* type-specific structures for kernfs_node union members */
57 struct kernfs_elem_dir {
58 unsigned long subdirs;
59 /* children rbtree starts here and goes through kn->rb */
60 struct rb_root children;
63 * The kernfs hierarchy this directory belongs to. This fits
64 * better directly in kernfs_node but is here to save space.
66 struct kernfs_root *root;
69 struct kernfs_elem_symlink {
70 struct kernfs_node *target_kn;
73 struct kernfs_elem_attr {
74 const struct kernfs_ops *ops;
75 struct kernfs_open_node *open;
80 * kernfs_node - the building block of kernfs hierarchy. Each and every
81 * kernfs node is represented by single kernfs_node. Most fields are
82 * private to kernfs and shouldn't be accessed directly by kernfs users.
84 * As long as s_count reference is held, the kernfs_node itself is
85 * accessible. Dereferencing elem or any other outer entity requires
91 #ifdef CONFIG_DEBUG_LOCK_ALLOC
92 struct lockdep_map dep_map;
95 * Use kernfs_get_parent() and kernfs_name/path() instead of
96 * accessing the following two fields directly. If the node is
97 * never moved to a different parent, it is safe to access the
100 struct kernfs_node *parent;
105 const void *ns; /* namespace tag */
106 unsigned int hash; /* ns + name hash */
108 struct kernfs_elem_dir dir;
109 struct kernfs_elem_symlink symlink;
110 struct kernfs_elem_attr attr;
115 unsigned short flags;
118 struct kernfs_iattrs *iattr;
122 * kernfs_syscall_ops may be specified on kernfs_create_root() to support
123 * syscalls. These optional callbacks are invoked on the matching syscalls
124 * and can perform any kernfs operations which don't necessarily have to be
125 * the exact operation requested. An active reference is held for each
126 * kernfs_node parameter.
128 struct kernfs_syscall_ops {
129 int (*remount_fs)(struct kernfs_root *root, int *flags, char *data);
130 int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
132 int (*mkdir)(struct kernfs_node *parent, const char *name,
134 int (*rmdir)(struct kernfs_node *kn);
135 int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
136 const char *new_name);
140 /* published fields */
141 struct kernfs_node *kn;
142 unsigned int flags; /* KERNFS_ROOT_* flags */
144 /* private fields, do not use outside kernfs proper */
146 struct kernfs_syscall_ops *syscall_ops;
147 wait_queue_head_t deactivate_waitq;
150 struct kernfs_open_file {
151 /* published fields */
152 struct kernfs_node *kn;
156 /* private fields, do not use outside kernfs proper */
159 struct list_head list;
161 size_t atomic_write_len;
163 const struct vm_operations_struct *vm_ops;
168 * Read is handled by either seq_file or raw_read().
170 * If seq_show() is present, seq_file path is active. Other seq
171 * operations are optional and if not implemented, the behavior is
172 * equivalent to single_open(). @sf->private points to the
173 * associated kernfs_open_file.
175 * read() is bounced through kernel buffer and a read larger than
176 * PAGE_SIZE results in partial operation of PAGE_SIZE.
178 int (*seq_show)(struct seq_file *sf, void *v);
180 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
181 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
182 void (*seq_stop)(struct seq_file *sf, void *v);
184 ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
188 * write() is bounced through kernel buffer. If atomic_write_len
189 * is not set, a write larger than PAGE_SIZE results in partial
190 * operations of PAGE_SIZE chunks. If atomic_write_len is set,
191 * writes upto the specified size are executed atomically but
192 * larger ones are rejected with -E2BIG.
194 size_t atomic_write_len;
195 ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
198 int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
200 #ifdef CONFIG_DEBUG_LOCK_ALLOC
201 struct lock_class_key lockdep_key;
207 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
209 return kn->flags & KERNFS_TYPE_MASK;
213 * kernfs_enable_ns - enable namespace under a directory
214 * @kn: directory of interest, should be empty
216 * This is to be called right after @kn is created to enable namespace
217 * under it. All children of @kn must have non-NULL namespace tags and
218 * only the ones which match the super_block's tag will be visible.
220 static inline void kernfs_enable_ns(struct kernfs_node *kn)
222 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
223 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
224 kn->flags |= KERNFS_NS;
228 * kernfs_ns_enabled - test whether namespace is enabled
229 * @kn: the node to test
231 * Test whether namespace filtering is enabled for the children of @ns.
233 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
235 return kn->flags & KERNFS_NS;
238 int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen);
239 char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
241 void pr_cont_kernfs_name(struct kernfs_node *kn);
242 void pr_cont_kernfs_path(struct kernfs_node *kn);
243 struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn);
244 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
245 const char *name, const void *ns);
246 void kernfs_get(struct kernfs_node *kn);
247 void kernfs_put(struct kernfs_node *kn);
249 struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry);
250 struct kernfs_root *kernfs_root_from_sb(struct super_block *sb);
252 struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
253 unsigned int flags, void *priv);
254 void kernfs_destroy_root(struct kernfs_root *root);
256 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
257 const char *name, umode_t mode,
258 void *priv, const void *ns);
259 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
261 umode_t mode, loff_t size,
262 const struct kernfs_ops *ops,
263 void *priv, const void *ns,
265 struct lock_class_key *key);
266 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
268 struct kernfs_node *target);
269 void kernfs_activate(struct kernfs_node *kn);
270 void kernfs_remove(struct kernfs_node *kn);
271 void kernfs_break_active_protection(struct kernfs_node *kn);
272 void kernfs_unbreak_active_protection(struct kernfs_node *kn);
273 bool kernfs_remove_self(struct kernfs_node *kn);
274 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
276 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
277 const char *new_name, const void *new_ns);
278 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
279 void kernfs_notify(struct kernfs_node *kn);
281 const void *kernfs_super_ns(struct super_block *sb);
282 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
283 struct kernfs_root *root, bool *new_sb_created,
285 void kernfs_kill_sb(struct super_block *sb);
287 void kernfs_init(void);
289 #else /* CONFIG_KERNFS */
291 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
292 { return 0; } /* whatever */
294 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
296 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
299 static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
302 static inline char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
306 static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { }
307 static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { }
309 static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
312 static inline struct kernfs_node *
313 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
317 static inline void kernfs_get(struct kernfs_node *kn) { }
318 static inline void kernfs_put(struct kernfs_node *kn) { }
320 static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
323 static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
326 static inline struct kernfs_root *
327 kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
329 { return ERR_PTR(-ENOSYS); }
331 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
333 static inline struct kernfs_node *
334 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
335 umode_t mode, void *priv, const void *ns)
336 { return ERR_PTR(-ENOSYS); }
338 static inline struct kernfs_node *
339 __kernfs_create_file(struct kernfs_node *parent, const char *name,
340 umode_t mode, loff_t size, const struct kernfs_ops *ops,
341 void *priv, const void *ns, bool name_is_static,
342 struct lock_class_key *key)
343 { return ERR_PTR(-ENOSYS); }
345 static inline struct kernfs_node *
346 kernfs_create_link(struct kernfs_node *parent, const char *name,
347 struct kernfs_node *target)
348 { return ERR_PTR(-ENOSYS); }
350 static inline void kernfs_activate(struct kernfs_node *kn) { }
352 static inline void kernfs_remove(struct kernfs_node *kn) { }
354 static inline bool kernfs_remove_self(struct kernfs_node *kn)
357 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
358 const char *name, const void *ns)
361 static inline int kernfs_rename_ns(struct kernfs_node *kn,
362 struct kernfs_node *new_parent,
363 const char *new_name, const void *new_ns)
366 static inline int kernfs_setattr(struct kernfs_node *kn,
367 const struct iattr *iattr)
370 static inline void kernfs_notify(struct kernfs_node *kn) { }
372 static inline const void *kernfs_super_ns(struct super_block *sb)
375 static inline struct dentry *
376 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
377 struct kernfs_root *root, bool *new_sb_created, const void *ns)
378 { return ERR_PTR(-ENOSYS); }
380 static inline void kernfs_kill_sb(struct super_block *sb) { }
382 static inline void kernfs_init(void) { }
384 #endif /* CONFIG_KERNFS */
386 static inline struct kernfs_node *
387 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
389 return kernfs_find_and_get_ns(kn, name, NULL);
392 static inline struct kernfs_node *
393 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
396 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
399 static inline struct kernfs_node *
400 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
401 umode_t mode, loff_t size, const struct kernfs_ops *ops,
402 void *priv, const void *ns)
404 struct lock_class_key *key = NULL;
406 #ifdef CONFIG_DEBUG_LOCK_ALLOC
407 key = (struct lock_class_key *)&ops->lockdep_key;
409 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
413 static inline struct kernfs_node *
414 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
415 loff_t size, const struct kernfs_ops *ops, void *priv)
417 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
420 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
423 return kernfs_remove_by_name_ns(parent, name, NULL);
426 static inline int kernfs_rename(struct kernfs_node *kn,
427 struct kernfs_node *new_parent,
428 const char *new_name)
430 return kernfs_rename_ns(kn, new_parent, new_name, NULL);
433 static inline struct dentry *
434 kernfs_mount(struct file_system_type *fs_type, int flags,
435 struct kernfs_root *root, bool *new_sb_created)
437 return kernfs_mount_ns(fs_type, flags, root, new_sb_created, NULL);
440 #endif /* __LINUX_KERNFS_H */