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_SUICIDAL
= 0x0400,
47 KERNFS_SUICIDED
= 0x0800,
48 KERNFS_EMPTY_DIR
= 0x1000,
51 /* @flags for kernfs_create_root() */
52 enum kernfs_root_flag
{
54 * kernfs_nodes are created in the deactivated state and invisible.
55 * They require explicit kernfs_activate() to become visible. This
56 * can be used to make related nodes become visible atomically
57 * after all nodes are created successfully.
59 KERNFS_ROOT_CREATE_DEACTIVATED
= 0x0001,
62 * For regular flies, if the opener has CAP_DAC_OVERRIDE, open(2)
63 * succeeds regardless of the RW permissions. sysfs had an extra
64 * layer of enforcement where open(2) fails with -EACCES regardless
65 * of CAP_DAC_OVERRIDE if the permission doesn't have the
66 * respective read or write access at all (none of S_IRUGO or
67 * S_IWUGO) or the respective operation isn't implemented. The
68 * following flag enables that behavior.
70 KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK
= 0x0002,
73 /* type-specific structures for kernfs_node union members */
74 struct kernfs_elem_dir
{
75 unsigned long subdirs
;
76 /* children rbtree starts here and goes through kn->rb */
77 struct rb_root children
;
80 * The kernfs hierarchy this directory belongs to. This fits
81 * better directly in kernfs_node but is here to save space.
83 struct kernfs_root
*root
;
86 struct kernfs_elem_symlink
{
87 struct kernfs_node
*target_kn
;
90 struct kernfs_elem_attr
{
91 const struct kernfs_ops
*ops
;
92 struct kernfs_open_node
*open
;
94 struct kernfs_node
*notify_next
; /* for kernfs_notify() */
98 * kernfs_node - the building block of kernfs hierarchy. Each and every
99 * kernfs node is represented by single kernfs_node. Most fields are
100 * private to kernfs and shouldn't be accessed directly by kernfs users.
102 * As long as s_count reference is held, the kernfs_node itself is
103 * accessible. Dereferencing elem or any other outer entity requires
109 #ifdef CONFIG_DEBUG_LOCK_ALLOC
110 struct lockdep_map dep_map
;
113 * Use kernfs_get_parent() and kernfs_name/path() instead of
114 * accessing the following two fields directly. If the node is
115 * never moved to a different parent, it is safe to access the
118 struct kernfs_node
*parent
;
123 const void *ns
; /* namespace tag */
124 unsigned int hash
; /* ns + name hash */
126 struct kernfs_elem_dir dir
;
127 struct kernfs_elem_symlink symlink
;
128 struct kernfs_elem_attr attr
;
133 unsigned short flags
;
136 struct kernfs_iattrs
*iattr
;
140 * kernfs_syscall_ops may be specified on kernfs_create_root() to support
141 * syscalls. These optional callbacks are invoked on the matching syscalls
142 * and can perform any kernfs operations which don't necessarily have to be
143 * the exact operation requested. An active reference is held for each
144 * kernfs_node parameter.
146 struct kernfs_syscall_ops
{
147 int (*remount_fs
)(struct kernfs_root
*root
, int *flags
, char *data
);
148 int (*show_options
)(struct seq_file
*sf
, struct kernfs_root
*root
);
150 int (*mkdir
)(struct kernfs_node
*parent
, const char *name
,
152 int (*rmdir
)(struct kernfs_node
*kn
);
153 int (*rename
)(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
154 const char *new_name
);
155 int (*show_path
)(struct seq_file
*sf
, struct kernfs_node
*kn
,
156 struct kernfs_root
*root
);
160 /* published fields */
161 struct kernfs_node
*kn
;
162 unsigned int flags
; /* KERNFS_ROOT_* flags */
164 /* private fields, do not use outside kernfs proper */
166 struct kernfs_syscall_ops
*syscall_ops
;
168 /* list of kernfs_super_info of this root, protected by kernfs_mutex */
169 struct list_head supers
;
171 wait_queue_head_t deactivate_waitq
;
174 struct kernfs_open_file
{
175 /* published fields */
176 struct kernfs_node
*kn
;
180 /* private fields, do not use outside kernfs proper */
182 struct mutex prealloc_mutex
;
184 struct list_head list
;
187 size_t atomic_write_len
;
189 const struct vm_operations_struct
*vm_ops
;
194 * Read is handled by either seq_file or raw_read().
196 * If seq_show() is present, seq_file path is active. Other seq
197 * operations are optional and if not implemented, the behavior is
198 * equivalent to single_open(). @sf->private points to the
199 * associated kernfs_open_file.
201 * read() is bounced through kernel buffer and a read larger than
202 * PAGE_SIZE results in partial operation of PAGE_SIZE.
204 int (*seq_show
)(struct seq_file
*sf
, void *v
);
206 void *(*seq_start
)(struct seq_file
*sf
, loff_t
*ppos
);
207 void *(*seq_next
)(struct seq_file
*sf
, void *v
, loff_t
*ppos
);
208 void (*seq_stop
)(struct seq_file
*sf
, void *v
);
210 ssize_t (*read
)(struct kernfs_open_file
*of
, char *buf
, size_t bytes
,
214 * write() is bounced through kernel buffer. If atomic_write_len
215 * is not set, a write larger than PAGE_SIZE results in partial
216 * operations of PAGE_SIZE chunks. If atomic_write_len is set,
217 * writes upto the specified size are executed atomically but
218 * larger ones are rejected with -E2BIG.
220 size_t atomic_write_len
;
222 * "prealloc" causes a buffer to be allocated at open for
223 * all read/write requests. As ->seq_show uses seq_read()
224 * which does its own allocation, it is incompatible with
225 * ->prealloc. Provide ->read and ->write with ->prealloc.
228 ssize_t (*write
)(struct kernfs_open_file
*of
, char *buf
, size_t bytes
,
231 int (*mmap
)(struct kernfs_open_file
*of
, struct vm_area_struct
*vma
);
233 #ifdef CONFIG_DEBUG_LOCK_ALLOC
234 struct lock_class_key lockdep_key
;
240 static inline enum kernfs_node_type
kernfs_type(struct kernfs_node
*kn
)
242 return kn
->flags
& KERNFS_TYPE_MASK
;
246 * kernfs_enable_ns - enable namespace under a directory
247 * @kn: directory of interest, should be empty
249 * This is to be called right after @kn is created to enable namespace
250 * under it. All children of @kn must have non-NULL namespace tags and
251 * only the ones which match the super_block's tag will be visible.
253 static inline void kernfs_enable_ns(struct kernfs_node
*kn
)
255 WARN_ON_ONCE(kernfs_type(kn
) != KERNFS_DIR
);
256 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn
->dir
.children
));
257 kn
->flags
|= KERNFS_NS
;
261 * kernfs_ns_enabled - test whether namespace is enabled
262 * @kn: the node to test
264 * Test whether namespace filtering is enabled for the children of @ns.
266 static inline bool kernfs_ns_enabled(struct kernfs_node
*kn
)
268 return kn
->flags
& KERNFS_NS
;
271 int kernfs_name(struct kernfs_node
*kn
, char *buf
, size_t buflen
);
272 int kernfs_path_from_node(struct kernfs_node
*root_kn
, struct kernfs_node
*kn
,
273 char *buf
, size_t buflen
);
274 void pr_cont_kernfs_name(struct kernfs_node
*kn
);
275 void pr_cont_kernfs_path(struct kernfs_node
*kn
);
276 struct kernfs_node
*kernfs_get_parent(struct kernfs_node
*kn
);
277 struct kernfs_node
*kernfs_find_and_get_ns(struct kernfs_node
*parent
,
278 const char *name
, const void *ns
);
279 struct kernfs_node
*kernfs_walk_and_get_ns(struct kernfs_node
*parent
,
280 const char *path
, const void *ns
);
281 void kernfs_get(struct kernfs_node
*kn
);
282 void kernfs_put(struct kernfs_node
*kn
);
284 struct kernfs_node
*kernfs_node_from_dentry(struct dentry
*dentry
);
285 struct kernfs_root
*kernfs_root_from_sb(struct super_block
*sb
);
286 struct inode
*kernfs_get_inode(struct super_block
*sb
, struct kernfs_node
*kn
);
288 struct dentry
*kernfs_node_dentry(struct kernfs_node
*kn
,
289 struct super_block
*sb
);
290 struct kernfs_root
*kernfs_create_root(struct kernfs_syscall_ops
*scops
,
291 unsigned int flags
, void *priv
);
292 void kernfs_destroy_root(struct kernfs_root
*root
);
294 struct kernfs_node
*kernfs_create_dir_ns(struct kernfs_node
*parent
,
295 const char *name
, umode_t mode
,
296 void *priv
, const void *ns
);
297 struct kernfs_node
*kernfs_create_empty_dir(struct kernfs_node
*parent
,
299 struct kernfs_node
*__kernfs_create_file(struct kernfs_node
*parent
,
301 umode_t mode
, loff_t size
,
302 const struct kernfs_ops
*ops
,
303 void *priv
, const void *ns
,
304 struct lock_class_key
*key
);
305 struct kernfs_node
*kernfs_create_link(struct kernfs_node
*parent
,
307 struct kernfs_node
*target
);
308 void kernfs_activate(struct kernfs_node
*kn
);
309 void kernfs_remove(struct kernfs_node
*kn
);
310 void kernfs_break_active_protection(struct kernfs_node
*kn
);
311 void kernfs_unbreak_active_protection(struct kernfs_node
*kn
);
312 bool kernfs_remove_self(struct kernfs_node
*kn
);
313 int kernfs_remove_by_name_ns(struct kernfs_node
*parent
, const char *name
,
315 int kernfs_rename_ns(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
316 const char *new_name
, const void *new_ns
);
317 int kernfs_setattr(struct kernfs_node
*kn
, const struct iattr
*iattr
);
318 void kernfs_notify(struct kernfs_node
*kn
);
320 const void *kernfs_super_ns(struct super_block
*sb
);
321 struct dentry
*kernfs_mount_ns(struct file_system_type
*fs_type
, int flags
,
322 struct kernfs_root
*root
, unsigned long magic
,
323 bool *new_sb_created
, const void *ns
);
324 void kernfs_kill_sb(struct super_block
*sb
);
325 struct super_block
*kernfs_pin_sb(struct kernfs_root
*root
, const void *ns
);
327 void kernfs_init(void);
329 #else /* CONFIG_KERNFS */
331 static inline enum kernfs_node_type
kernfs_type(struct kernfs_node
*kn
)
332 { return 0; } /* whatever */
334 static inline void kernfs_enable_ns(struct kernfs_node
*kn
) { }
336 static inline bool kernfs_ns_enabled(struct kernfs_node
*kn
)
339 static inline int kernfs_name(struct kernfs_node
*kn
, char *buf
, size_t buflen
)
342 static inline int kernfs_path_from_node(struct kernfs_node
*root_kn
,
343 struct kernfs_node
*kn
,
344 char *buf
, size_t buflen
)
347 static inline void pr_cont_kernfs_name(struct kernfs_node
*kn
) { }
348 static inline void pr_cont_kernfs_path(struct kernfs_node
*kn
) { }
350 static inline struct kernfs_node
*kernfs_get_parent(struct kernfs_node
*kn
)
353 static inline struct kernfs_node
*
354 kernfs_find_and_get_ns(struct kernfs_node
*parent
, const char *name
,
357 static inline struct kernfs_node
*
358 kernfs_walk_and_get_ns(struct kernfs_node
*parent
, const char *path
,
362 static inline void kernfs_get(struct kernfs_node
*kn
) { }
363 static inline void kernfs_put(struct kernfs_node
*kn
) { }
365 static inline struct kernfs_node
*kernfs_node_from_dentry(struct dentry
*dentry
)
368 static inline struct kernfs_root
*kernfs_root_from_sb(struct super_block
*sb
)
371 static inline struct inode
*
372 kernfs_get_inode(struct super_block
*sb
, struct kernfs_node
*kn
)
375 static inline struct kernfs_root
*
376 kernfs_create_root(struct kernfs_syscall_ops
*scops
, unsigned int flags
,
378 { return ERR_PTR(-ENOSYS
); }
380 static inline void kernfs_destroy_root(struct kernfs_root
*root
) { }
382 static inline struct kernfs_node
*
383 kernfs_create_dir_ns(struct kernfs_node
*parent
, const char *name
,
384 umode_t mode
, void *priv
, const void *ns
)
385 { return ERR_PTR(-ENOSYS
); }
387 static inline struct kernfs_node
*
388 __kernfs_create_file(struct kernfs_node
*parent
, const char *name
,
389 umode_t mode
, loff_t size
, const struct kernfs_ops
*ops
,
390 void *priv
, const void *ns
, struct lock_class_key
*key
)
391 { return ERR_PTR(-ENOSYS
); }
393 static inline struct kernfs_node
*
394 kernfs_create_link(struct kernfs_node
*parent
, const char *name
,
395 struct kernfs_node
*target
)
396 { return ERR_PTR(-ENOSYS
); }
398 static inline void kernfs_activate(struct kernfs_node
*kn
) { }
400 static inline void kernfs_remove(struct kernfs_node
*kn
) { }
402 static inline bool kernfs_remove_self(struct kernfs_node
*kn
)
405 static inline int kernfs_remove_by_name_ns(struct kernfs_node
*kn
,
406 const char *name
, const void *ns
)
409 static inline int kernfs_rename_ns(struct kernfs_node
*kn
,
410 struct kernfs_node
*new_parent
,
411 const char *new_name
, const void *new_ns
)
414 static inline int kernfs_setattr(struct kernfs_node
*kn
,
415 const struct iattr
*iattr
)
418 static inline void kernfs_notify(struct kernfs_node
*kn
) { }
420 static inline const void *kernfs_super_ns(struct super_block
*sb
)
423 static inline struct dentry
*
424 kernfs_mount_ns(struct file_system_type
*fs_type
, int flags
,
425 struct kernfs_root
*root
, unsigned long magic
,
426 bool *new_sb_created
, const void *ns
)
427 { return ERR_PTR(-ENOSYS
); }
429 static inline void kernfs_kill_sb(struct super_block
*sb
) { }
431 static inline void kernfs_init(void) { }
433 #endif /* CONFIG_KERNFS */
436 * kernfs_path - build full path of a given node
437 * @kn: kernfs_node of interest
438 * @buf: buffer to copy @kn's name into
439 * @buflen: size of @buf
441 * Builds and returns the full path of @kn in @buf of @buflen bytes. The
442 * path is built from the end of @buf so the returned pointer usually
443 * doesn't match @buf. If @buf isn't long enough, @buf is nul terminated
444 * and %NULL is returned.
446 static inline int kernfs_path(struct kernfs_node
*kn
, char *buf
, size_t buflen
)
448 return kernfs_path_from_node(kn
, NULL
, buf
, buflen
);
451 static inline struct kernfs_node
*
452 kernfs_find_and_get(struct kernfs_node
*kn
, const char *name
)
454 return kernfs_find_and_get_ns(kn
, name
, NULL
);
457 static inline struct kernfs_node
*
458 kernfs_walk_and_get(struct kernfs_node
*kn
, const char *path
)
460 return kernfs_walk_and_get_ns(kn
, path
, NULL
);
463 static inline struct kernfs_node
*
464 kernfs_create_dir(struct kernfs_node
*parent
, const char *name
, umode_t mode
,
467 return kernfs_create_dir_ns(parent
, name
, mode
, priv
, NULL
);
470 static inline struct kernfs_node
*
471 kernfs_create_file_ns(struct kernfs_node
*parent
, const char *name
,
472 umode_t mode
, loff_t size
, const struct kernfs_ops
*ops
,
473 void *priv
, const void *ns
)
475 struct lock_class_key
*key
= NULL
;
477 #ifdef CONFIG_DEBUG_LOCK_ALLOC
478 key
= (struct lock_class_key
*)&ops
->lockdep_key
;
480 return __kernfs_create_file(parent
, name
, mode
, size
, ops
, priv
, ns
,
484 static inline struct kernfs_node
*
485 kernfs_create_file(struct kernfs_node
*parent
, const char *name
, umode_t mode
,
486 loff_t size
, const struct kernfs_ops
*ops
, void *priv
)
488 return kernfs_create_file_ns(parent
, name
, mode
, size
, ops
, priv
, NULL
);
491 static inline int kernfs_remove_by_name(struct kernfs_node
*parent
,
494 return kernfs_remove_by_name_ns(parent
, name
, NULL
);
497 static inline int kernfs_rename(struct kernfs_node
*kn
,
498 struct kernfs_node
*new_parent
,
499 const char *new_name
)
501 return kernfs_rename_ns(kn
, new_parent
, new_name
, NULL
);
504 static inline struct dentry
*
505 kernfs_mount(struct file_system_type
*fs_type
, int flags
,
506 struct kernfs_root
*root
, unsigned long magic
,
507 bool *new_sb_created
)
509 return kernfs_mount_ns(fs_type
, flags
, root
,
510 magic
, new_sb_created
, NULL
);
513 #endif /* __LINUX_KERNFS_H */