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);
280 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
282 struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
283 unsigned int flags, void *priv);
284 void kernfs_destroy_root(struct kernfs_root *root);
286 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
287 const char *name, umode_t mode,
288 void *priv, const void *ns);
289 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
291 umode_t mode, loff_t size,
292 const struct kernfs_ops *ops,
293 void *priv, const void *ns,
294 struct lock_class_key *key);
295 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
297 struct kernfs_node *target);
298 void kernfs_activate(struct kernfs_node *kn);
299 void kernfs_remove(struct kernfs_node *kn);
300 void kernfs_break_active_protection(struct kernfs_node *kn);
301 void kernfs_unbreak_active_protection(struct kernfs_node *kn);
302 bool kernfs_remove_self(struct kernfs_node *kn);
303 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
305 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
306 const char *new_name, const void *new_ns);
307 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
308 void kernfs_notify(struct kernfs_node *kn);
310 const void *kernfs_super_ns(struct super_block *sb);
311 struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
312 struct kernfs_root *root, unsigned long magic,
313 bool *new_sb_created, const void *ns);
314 void kernfs_kill_sb(struct super_block *sb);
315 struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns);
317 void kernfs_init(void);
319 #else /* CONFIG_KERNFS */
321 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
322 { return 0; } /* whatever */
324 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
326 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
329 static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
332 static inline char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
336 static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { }
337 static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { }
339 static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
342 static inline struct kernfs_node *
343 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
347 static inline void kernfs_get(struct kernfs_node *kn) { }
348 static inline void kernfs_put(struct kernfs_node *kn) { }
350 static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
353 static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
356 static inline struct inode *
357 kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
360 static inline struct kernfs_root *
361 kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
363 { return ERR_PTR(-ENOSYS); }
365 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
367 static inline struct kernfs_node *
368 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
369 umode_t mode, void *priv, const void *ns)
370 { return ERR_PTR(-ENOSYS); }
372 static inline struct kernfs_node *
373 __kernfs_create_file(struct kernfs_node *parent, const char *name,
374 umode_t mode, loff_t size, const struct kernfs_ops *ops,
375 void *priv, const void *ns, struct lock_class_key *key)
376 { return ERR_PTR(-ENOSYS); }
378 static inline struct kernfs_node *
379 kernfs_create_link(struct kernfs_node *parent, const char *name,
380 struct kernfs_node *target)
381 { return ERR_PTR(-ENOSYS); }
383 static inline void kernfs_activate(struct kernfs_node *kn) { }
385 static inline void kernfs_remove(struct kernfs_node *kn) { }
387 static inline bool kernfs_remove_self(struct kernfs_node *kn)
390 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
391 const char *name, const void *ns)
394 static inline int kernfs_rename_ns(struct kernfs_node *kn,
395 struct kernfs_node *new_parent,
396 const char *new_name, const void *new_ns)
399 static inline int kernfs_setattr(struct kernfs_node *kn,
400 const struct iattr *iattr)
403 static inline void kernfs_notify(struct kernfs_node *kn) { }
405 static inline const void *kernfs_super_ns(struct super_block *sb)
408 static inline struct dentry *
409 kernfs_mount_ns(struct file_system_type *fs_type, int flags,
410 struct kernfs_root *root, unsigned long magic,
411 bool *new_sb_created, const void *ns)
412 { return ERR_PTR(-ENOSYS); }
414 static inline void kernfs_kill_sb(struct super_block *sb) { }
416 static inline void kernfs_init(void) { }
418 #endif /* CONFIG_KERNFS */
420 static inline struct kernfs_node *
421 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
423 return kernfs_find_and_get_ns(kn, name, NULL);
426 static inline struct kernfs_node *
427 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
430 return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
433 static inline struct kernfs_node *
434 kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
435 umode_t mode, loff_t size, const struct kernfs_ops *ops,
436 void *priv, const void *ns)
438 struct lock_class_key *key = NULL;
440 #ifdef CONFIG_DEBUG_LOCK_ALLOC
441 key = (struct lock_class_key *)&ops->lockdep_key;
443 return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
447 static inline struct kernfs_node *
448 kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
449 loff_t size, const struct kernfs_ops *ops, void *priv)
451 return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
454 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
457 return kernfs_remove_by_name_ns(parent, name, NULL);
460 static inline int kernfs_rename(struct kernfs_node *kn,
461 struct kernfs_node *new_parent,
462 const char *new_name)
464 return kernfs_rename_ns(kn, new_parent, new_name, NULL);
467 static inline struct dentry *
468 kernfs_mount(struct file_system_type *fs_type, int flags,
469 struct kernfs_root *root, unsigned long magic,
470 bool *new_sb_created)
472 return kernfs_mount_ns(fs_type, flags, root,
473 magic, new_sb_created, NULL);
476 #endif /* __LINUX_KERNFS_H */