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,
50 /* @flags for kernfs_create_root() */
51 enum kernfs_root_flag
{
53 * kernfs_nodes are created in the deactivated state and invisible.
54 * They require explicit kernfs_activate() to become visible. This
55 * can be used to make related nodes become visible atomically
56 * after all nodes are created successfully.
58 KERNFS_ROOT_CREATE_DEACTIVATED
= 0x0001,
61 * For regular flies, if the opener has CAP_DAC_OVERRIDE, open(2)
62 * succeeds regardless of the RW permissions. sysfs had an extra
63 * layer of enforcement where open(2) fails with -EACCES regardless
64 * of CAP_DAC_OVERRIDE if the permission doesn't have the
65 * respective read or write access at all (none of S_IRUGO or
66 * S_IWUGO) or the respective operation isn't implemented. The
67 * following flag enables that behavior.
69 KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK
= 0x0002,
72 /* type-specific structures for kernfs_node union members */
73 struct kernfs_elem_dir
{
74 unsigned long subdirs
;
75 /* children rbtree starts here and goes through kn->rb */
76 struct rb_root children
;
79 * The kernfs hierarchy this directory belongs to. This fits
80 * better directly in kernfs_node but is here to save space.
82 struct kernfs_root
*root
;
85 struct kernfs_elem_symlink
{
86 struct kernfs_node
*target_kn
;
89 struct kernfs_elem_attr
{
90 const struct kernfs_ops
*ops
;
91 struct kernfs_open_node
*open
;
93 struct kernfs_node
*notify_next
; /* for kernfs_notify() */
97 * kernfs_node - the building block of kernfs hierarchy. Each and every
98 * kernfs node is represented by single kernfs_node. Most fields are
99 * private to kernfs and shouldn't be accessed directly by kernfs users.
101 * As long as s_count reference is held, the kernfs_node itself is
102 * accessible. Dereferencing elem or any other outer entity requires
108 #ifdef CONFIG_DEBUG_LOCK_ALLOC
109 struct lockdep_map dep_map
;
112 * Use kernfs_get_parent() and kernfs_name/path() instead of
113 * accessing the following two fields directly. If the node is
114 * never moved to a different parent, it is safe to access the
117 struct kernfs_node
*parent
;
122 const void *ns
; /* namespace tag */
123 unsigned int hash
; /* ns + name hash */
125 struct kernfs_elem_dir dir
;
126 struct kernfs_elem_symlink symlink
;
127 struct kernfs_elem_attr attr
;
132 unsigned short flags
;
135 struct kernfs_iattrs
*iattr
;
139 * kernfs_syscall_ops may be specified on kernfs_create_root() to support
140 * syscalls. These optional callbacks are invoked on the matching syscalls
141 * and can perform any kernfs operations which don't necessarily have to be
142 * the exact operation requested. An active reference is held for each
143 * kernfs_node parameter.
145 struct kernfs_syscall_ops
{
146 int (*remount_fs
)(struct kernfs_root
*root
, int *flags
, char *data
);
147 int (*show_options
)(struct seq_file
*sf
, struct kernfs_root
*root
);
149 int (*mkdir
)(struct kernfs_node
*parent
, const char *name
,
151 int (*rmdir
)(struct kernfs_node
*kn
);
152 int (*rename
)(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
153 const char *new_name
);
157 /* published fields */
158 struct kernfs_node
*kn
;
159 unsigned int flags
; /* KERNFS_ROOT_* flags */
161 /* private fields, do not use outside kernfs proper */
163 struct kernfs_syscall_ops
*syscall_ops
;
165 /* list of kernfs_super_info of this root, protected by kernfs_mutex */
166 struct list_head supers
;
168 wait_queue_head_t deactivate_waitq
;
171 struct kernfs_open_file
{
172 /* published fields */
173 struct kernfs_node
*kn
;
177 /* private fields, do not use outside kernfs proper */
180 struct list_head list
;
183 size_t atomic_write_len
;
185 const struct vm_operations_struct
*vm_ops
;
190 * Read is handled by either seq_file or raw_read().
192 * If seq_show() is present, seq_file path is active. Other seq
193 * operations are optional and if not implemented, the behavior is
194 * equivalent to single_open(). @sf->private points to the
195 * associated kernfs_open_file.
197 * read() is bounced through kernel buffer and a read larger than
198 * PAGE_SIZE results in partial operation of PAGE_SIZE.
200 int (*seq_show
)(struct seq_file
*sf
, void *v
);
202 void *(*seq_start
)(struct seq_file
*sf
, loff_t
*ppos
);
203 void *(*seq_next
)(struct seq_file
*sf
, void *v
, loff_t
*ppos
);
204 void (*seq_stop
)(struct seq_file
*sf
, void *v
);
206 ssize_t (*read
)(struct kernfs_open_file
*of
, char *buf
, size_t bytes
,
210 * write() is bounced through kernel buffer. If atomic_write_len
211 * is not set, a write larger than PAGE_SIZE results in partial
212 * operations of PAGE_SIZE chunks. If atomic_write_len is set,
213 * writes upto the specified size are executed atomically but
214 * larger ones are rejected with -E2BIG.
216 size_t atomic_write_len
;
218 * "prealloc" causes a buffer to be allocated at open for
219 * all read/write requests. As ->seq_show uses seq_read()
220 * which does its own allocation, it is incompatible with
221 * ->prealloc. Provide ->read and ->write with ->prealloc.
224 ssize_t (*write
)(struct kernfs_open_file
*of
, char *buf
, size_t bytes
,
227 int (*mmap
)(struct kernfs_open_file
*of
, struct vm_area_struct
*vma
);
229 #ifdef CONFIG_DEBUG_LOCK_ALLOC
230 struct lock_class_key lockdep_key
;
236 static inline enum kernfs_node_type
kernfs_type(struct kernfs_node
*kn
)
238 return kn
->flags
& KERNFS_TYPE_MASK
;
242 * kernfs_enable_ns - enable namespace under a directory
243 * @kn: directory of interest, should be empty
245 * This is to be called right after @kn is created to enable namespace
246 * under it. All children of @kn must have non-NULL namespace tags and
247 * only the ones which match the super_block's tag will be visible.
249 static inline void kernfs_enable_ns(struct kernfs_node
*kn
)
251 WARN_ON_ONCE(kernfs_type(kn
) != KERNFS_DIR
);
252 WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn
->dir
.children
));
253 kn
->flags
|= KERNFS_NS
;
257 * kernfs_ns_enabled - test whether namespace is enabled
258 * @kn: the node to test
260 * Test whether namespace filtering is enabled for the children of @ns.
262 static inline bool kernfs_ns_enabled(struct kernfs_node
*kn
)
264 return kn
->flags
& KERNFS_NS
;
267 int kernfs_name(struct kernfs_node
*kn
, char *buf
, size_t buflen
);
268 char * __must_check
kernfs_path(struct kernfs_node
*kn
, char *buf
,
270 void pr_cont_kernfs_name(struct kernfs_node
*kn
);
271 void pr_cont_kernfs_path(struct kernfs_node
*kn
);
272 struct kernfs_node
*kernfs_get_parent(struct kernfs_node
*kn
);
273 struct kernfs_node
*kernfs_find_and_get_ns(struct kernfs_node
*parent
,
274 const char *name
, const void *ns
);
275 void kernfs_get(struct kernfs_node
*kn
);
276 void kernfs_put(struct kernfs_node
*kn
);
278 struct kernfs_node
*kernfs_node_from_dentry(struct dentry
*dentry
);
279 struct kernfs_root
*kernfs_root_from_sb(struct super_block
*sb
);
281 struct kernfs_root
*kernfs_create_root(struct kernfs_syscall_ops
*scops
,
282 unsigned int flags
, void *priv
);
283 void kernfs_destroy_root(struct kernfs_root
*root
);
285 struct kernfs_node
*kernfs_create_dir_ns(struct kernfs_node
*parent
,
286 const char *name
, umode_t mode
,
287 void *priv
, const void *ns
);
288 struct kernfs_node
*__kernfs_create_file(struct kernfs_node
*parent
,
290 umode_t mode
, loff_t size
,
291 const struct kernfs_ops
*ops
,
292 void *priv
, const void *ns
,
293 struct lock_class_key
*key
);
294 struct kernfs_node
*kernfs_create_link(struct kernfs_node
*parent
,
296 struct kernfs_node
*target
);
297 void kernfs_activate(struct kernfs_node
*kn
);
298 void kernfs_remove(struct kernfs_node
*kn
);
299 void kernfs_break_active_protection(struct kernfs_node
*kn
);
300 void kernfs_unbreak_active_protection(struct kernfs_node
*kn
);
301 bool kernfs_remove_self(struct kernfs_node
*kn
);
302 int kernfs_remove_by_name_ns(struct kernfs_node
*parent
, const char *name
,
304 int kernfs_rename_ns(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
305 const char *new_name
, const void *new_ns
);
306 int kernfs_setattr(struct kernfs_node
*kn
, const struct iattr
*iattr
);
307 void kernfs_notify(struct kernfs_node
*kn
);
309 const void *kernfs_super_ns(struct super_block
*sb
);
310 struct dentry
*kernfs_mount_ns(struct file_system_type
*fs_type
, int flags
,
311 struct kernfs_root
*root
, unsigned long magic
,
312 bool *new_sb_created
, const void *ns
);
313 void kernfs_kill_sb(struct super_block
*sb
);
314 struct super_block
*kernfs_pin_sb(struct kernfs_root
*root
, const void *ns
);
316 void kernfs_init(void);
318 #else /* CONFIG_KERNFS */
320 static inline enum kernfs_node_type
kernfs_type(struct kernfs_node
*kn
)
321 { return 0; } /* whatever */
323 static inline void kernfs_enable_ns(struct kernfs_node
*kn
) { }
325 static inline bool kernfs_ns_enabled(struct kernfs_node
*kn
)
328 static inline int kernfs_name(struct kernfs_node
*kn
, char *buf
, size_t buflen
)
331 static inline char * __must_check
kernfs_path(struct kernfs_node
*kn
, char *buf
,
335 static inline void pr_cont_kernfs_name(struct kernfs_node
*kn
) { }
336 static inline void pr_cont_kernfs_path(struct kernfs_node
*kn
) { }
338 static inline struct kernfs_node
*kernfs_get_parent(struct kernfs_node
*kn
)
341 static inline struct kernfs_node
*
342 kernfs_find_and_get_ns(struct kernfs_node
*parent
, const char *name
,
346 static inline void kernfs_get(struct kernfs_node
*kn
) { }
347 static inline void kernfs_put(struct kernfs_node
*kn
) { }
349 static inline struct kernfs_node
*kernfs_node_from_dentry(struct dentry
*dentry
)
352 static inline struct kernfs_root
*kernfs_root_from_sb(struct super_block
*sb
)
355 static inline struct kernfs_root
*
356 kernfs_create_root(struct kernfs_syscall_ops
*scops
, unsigned int flags
,
358 { return ERR_PTR(-ENOSYS
); }
360 static inline void kernfs_destroy_root(struct kernfs_root
*root
) { }
362 static inline struct kernfs_node
*
363 kernfs_create_dir_ns(struct kernfs_node
*parent
, const char *name
,
364 umode_t mode
, void *priv
, const void *ns
)
365 { return ERR_PTR(-ENOSYS
); }
367 static inline struct kernfs_node
*
368 __kernfs_create_file(struct kernfs_node
*parent
, const char *name
,
369 umode_t mode
, loff_t size
, const struct kernfs_ops
*ops
,
370 void *priv
, const void *ns
, struct lock_class_key
*key
)
371 { return ERR_PTR(-ENOSYS
); }
373 static inline struct kernfs_node
*
374 kernfs_create_link(struct kernfs_node
*parent
, const char *name
,
375 struct kernfs_node
*target
)
376 { return ERR_PTR(-ENOSYS
); }
378 static inline void kernfs_activate(struct kernfs_node
*kn
) { }
380 static inline void kernfs_remove(struct kernfs_node
*kn
) { }
382 static inline bool kernfs_remove_self(struct kernfs_node
*kn
)
385 static inline int kernfs_remove_by_name_ns(struct kernfs_node
*kn
,
386 const char *name
, const void *ns
)
389 static inline int kernfs_rename_ns(struct kernfs_node
*kn
,
390 struct kernfs_node
*new_parent
,
391 const char *new_name
, const void *new_ns
)
394 static inline int kernfs_setattr(struct kernfs_node
*kn
,
395 const struct iattr
*iattr
)
398 static inline void kernfs_notify(struct kernfs_node
*kn
) { }
400 static inline const void *kernfs_super_ns(struct super_block
*sb
)
403 static inline struct dentry
*
404 kernfs_mount_ns(struct file_system_type
*fs_type
, int flags
,
405 struct kernfs_root
*root
, unsigned long magic
,
406 bool *new_sb_created
, const void *ns
)
407 { return ERR_PTR(-ENOSYS
); }
409 static inline void kernfs_kill_sb(struct super_block
*sb
) { }
411 static inline void kernfs_init(void) { }
413 #endif /* CONFIG_KERNFS */
415 static inline struct kernfs_node
*
416 kernfs_find_and_get(struct kernfs_node
*kn
, const char *name
)
418 return kernfs_find_and_get_ns(kn
, name
, NULL
);
421 static inline struct kernfs_node
*
422 kernfs_create_dir(struct kernfs_node
*parent
, const char *name
, umode_t mode
,
425 return kernfs_create_dir_ns(parent
, name
, mode
, priv
, NULL
);
428 static inline struct kernfs_node
*
429 kernfs_create_file_ns(struct kernfs_node
*parent
, const char *name
,
430 umode_t mode
, loff_t size
, const struct kernfs_ops
*ops
,
431 void *priv
, const void *ns
)
433 struct lock_class_key
*key
= NULL
;
435 #ifdef CONFIG_DEBUG_LOCK_ALLOC
436 key
= (struct lock_class_key
*)&ops
->lockdep_key
;
438 return __kernfs_create_file(parent
, name
, mode
, size
, ops
, priv
, ns
,
442 static inline struct kernfs_node
*
443 kernfs_create_file(struct kernfs_node
*parent
, const char *name
, umode_t mode
,
444 loff_t size
, const struct kernfs_ops
*ops
, void *priv
)
446 return kernfs_create_file_ns(parent
, name
, mode
, size
, ops
, priv
, NULL
);
449 static inline int kernfs_remove_by_name(struct kernfs_node
*parent
,
452 return kernfs_remove_by_name_ns(parent
, name
, NULL
);
455 static inline int kernfs_rename(struct kernfs_node
*kn
,
456 struct kernfs_node
*new_parent
,
457 const char *new_name
)
459 return kernfs_rename_ns(kn
, new_parent
, new_name
, NULL
);
462 static inline struct dentry
*
463 kernfs_mount(struct file_system_type
*fs_type
, int flags
,
464 struct kernfs_root
*root
, unsigned long magic
,
465 bool *new_sb_created
)
467 return kernfs_mount_ns(fs_type
, flags
, root
,
468 magic
, new_sb_created
, NULL
);
471 #endif /* __LINUX_KERNFS_H */