xref: /openbmc/linux/include/linux/kernfs.h (revision 4b1f991b)
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * kernfs.h - pseudo filesystem decoupled from vfs locking
4  */
5 
6 #ifndef __LINUX_KERNFS_H
7 #define __LINUX_KERNFS_H
8 
9 #include <linux/err.h>
10 #include <linux/list.h>
11 #include <linux/mutex.h>
12 #include <linux/idr.h>
13 #include <linux/lockdep.h>
14 #include <linux/rbtree.h>
15 #include <linux/atomic.h>
16 #include <linux/bug.h>
17 #include <linux/types.h>
18 #include <linux/uidgid.h>
19 #include <linux/wait.h>
20 #include <linux/rwsem.h>
21 #include <linux/cache.h>
22 
23 struct file;
24 struct dentry;
25 struct iattr;
26 struct seq_file;
27 struct vm_area_struct;
28 struct vm_operations_struct;
29 struct super_block;
30 struct file_system_type;
31 struct poll_table_struct;
32 struct fs_context;
33 
34 struct kernfs_fs_context;
35 struct kernfs_open_node;
36 struct kernfs_iattrs;
37 
38 /*
39  * NR_KERNFS_LOCK_BITS determines size (NR_KERNFS_LOCKS) of hash
40  * table of locks.
41  * Having a small hash table would impact scalability, since
42  * more and more kernfs_node objects will end up using same lock
43  * and having a very large hash table would waste memory.
44  *
45  * At the moment size of hash table of locks is being set based on
46  * the number of CPUs as follows:
47  *
48  * NR_CPU      NR_KERNFS_LOCK_BITS      NR_KERNFS_LOCKS
49  *   1                  1                       2
50  *  2-3                 2                       4
51  *  4-7                 4                       16
52  *  8-15                6                       64
53  *  16-31               8                       256
54  *  32 and more         10                      1024
55  *
56  * The above relation between NR_CPU and number of locks is based
57  * on some internal experimentation which involved booting qemu
58  * with different values of smp, performing some sysfs operations
59  * on all CPUs and observing how increase in number of locks impacts
60  * completion time of these sysfs operations on each CPU.
61  */
62 #ifdef CONFIG_SMP
63 #define NR_KERNFS_LOCK_BITS (2 * (ilog2(NR_CPUS < 32 ? NR_CPUS : 32)))
64 #else
65 #define NR_KERNFS_LOCK_BITS     1
66 #endif
67 
68 #define NR_KERNFS_LOCKS     (1 << NR_KERNFS_LOCK_BITS)
69 
70 /*
71  * There's one kernfs_open_file for each open file and one kernfs_open_node
72  * for each kernfs_node with one or more open files.
73  *
74  * filp->private_data points to seq_file whose ->private points to
75  * kernfs_open_file.
76  *
77  * kernfs_open_files are chained at kernfs_open_node->files, which is
78  * protected by kernfs_global_locks.open_file_mutex[i].
79  *
80  * To reduce possible contention in sysfs access, arising due to single
81  * locks, use an array of locks (e.g. open_file_mutex) and use kernfs_node
82  * object address as hash keys to get the index of these locks.
83  *
84  * Hashed mutexes are safe to use here because operations using these don't
85  * rely on global exclusion.
86  *
87  * In future we intend to replace other global locks with hashed ones as well.
88  * kernfs_global_locks acts as a holder for all such hash tables.
89  */
90 struct kernfs_global_locks {
91 	struct mutex open_file_mutex[NR_KERNFS_LOCKS];
92 };
93 
94 enum kernfs_node_type {
95 	KERNFS_DIR		= 0x0001,
96 	KERNFS_FILE		= 0x0002,
97 	KERNFS_LINK		= 0x0004,
98 };
99 
100 #define KERNFS_TYPE_MASK		0x000f
101 #define KERNFS_FLAG_MASK		~KERNFS_TYPE_MASK
102 #define KERNFS_MAX_USER_XATTRS		128
103 #define KERNFS_USER_XATTR_SIZE_LIMIT	(128 << 10)
104 
105 enum kernfs_node_flag {
106 	KERNFS_ACTIVATED	= 0x0010,
107 	KERNFS_NS		= 0x0020,
108 	KERNFS_HAS_SEQ_SHOW	= 0x0040,
109 	KERNFS_HAS_MMAP		= 0x0080,
110 	KERNFS_LOCKDEP		= 0x0100,
111 	KERNFS_HIDDEN		= 0x0200,
112 	KERNFS_SUICIDAL		= 0x0400,
113 	KERNFS_SUICIDED		= 0x0800,
114 	KERNFS_EMPTY_DIR	= 0x1000,
115 	KERNFS_HAS_RELEASE	= 0x2000,
116 	KERNFS_REMOVING		= 0x4000,
117 };
118 
119 /* @flags for kernfs_create_root() */
120 enum kernfs_root_flag {
121 	/*
122 	 * kernfs_nodes are created in the deactivated state and invisible.
123 	 * They require explicit kernfs_activate() to become visible.  This
124 	 * can be used to make related nodes become visible atomically
125 	 * after all nodes are created successfully.
126 	 */
127 	KERNFS_ROOT_CREATE_DEACTIVATED		= 0x0001,
128 
129 	/*
130 	 * For regular files, if the opener has CAP_DAC_OVERRIDE, open(2)
131 	 * succeeds regardless of the RW permissions.  sysfs had an extra
132 	 * layer of enforcement where open(2) fails with -EACCES regardless
133 	 * of CAP_DAC_OVERRIDE if the permission doesn't have the
134 	 * respective read or write access at all (none of S_IRUGO or
135 	 * S_IWUGO) or the respective operation isn't implemented.  The
136 	 * following flag enables that behavior.
137 	 */
138 	KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK	= 0x0002,
139 
140 	/*
141 	 * The filesystem supports exportfs operation, so userspace can use
142 	 * fhandle to access nodes of the fs.
143 	 */
144 	KERNFS_ROOT_SUPPORT_EXPORTOP		= 0x0004,
145 
146 	/*
147 	 * Support user xattrs to be written to nodes rooted at this root.
148 	 */
149 	KERNFS_ROOT_SUPPORT_USER_XATTR		= 0x0008,
150 };
151 
152 /* type-specific structures for kernfs_node union members */
153 struct kernfs_elem_dir {
154 	unsigned long		subdirs;
155 	/* children rbtree starts here and goes through kn->rb */
156 	struct rb_root		children;
157 
158 	/*
159 	 * The kernfs hierarchy this directory belongs to.  This fits
160 	 * better directly in kernfs_node but is here to save space.
161 	 */
162 	struct kernfs_root	*root;
163 	/*
164 	 * Monotonic revision counter, used to identify if a directory
165 	 * node has changed during negative dentry revalidation.
166 	 */
167 	unsigned long		rev;
168 };
169 
170 struct kernfs_elem_symlink {
171 	struct kernfs_node	*target_kn;
172 };
173 
174 struct kernfs_elem_attr {
175 	const struct kernfs_ops	*ops;
176 	struct kernfs_open_node __rcu	*open;
177 	loff_t			size;
178 	struct kernfs_node	*notify_next;	/* for kernfs_notify() */
179 };
180 
181 /*
182  * kernfs_node - the building block of kernfs hierarchy.  Each and every
183  * kernfs node is represented by single kernfs_node.  Most fields are
184  * private to kernfs and shouldn't be accessed directly by kernfs users.
185  *
186  * As long as count reference is held, the kernfs_node itself is
187  * accessible.  Dereferencing elem or any other outer entity requires
188  * active reference.
189  */
190 struct kernfs_node {
191 	atomic_t		count;
192 	atomic_t		active;
193 #ifdef CONFIG_DEBUG_LOCK_ALLOC
194 	struct lockdep_map	dep_map;
195 #endif
196 	/*
197 	 * Use kernfs_get_parent() and kernfs_name/path() instead of
198 	 * accessing the following two fields directly.  If the node is
199 	 * never moved to a different parent, it is safe to access the
200 	 * parent directly.
201 	 */
202 	struct kernfs_node	*parent;
203 	const char		*name;
204 
205 	struct rb_node		rb;
206 
207 	const void		*ns;	/* namespace tag */
208 	unsigned int		hash;	/* ns + name hash */
209 	union {
210 		struct kernfs_elem_dir		dir;
211 		struct kernfs_elem_symlink	symlink;
212 		struct kernfs_elem_attr		attr;
213 	};
214 
215 	void			*priv;
216 
217 	/*
218 	 * 64bit unique ID.  On 64bit ino setups, id is the ino.  On 32bit,
219 	 * the low 32bits are ino and upper generation.
220 	 */
221 	u64			id;
222 
223 	unsigned short		flags;
224 	umode_t			mode;
225 	struct kernfs_iattrs	*iattr;
226 
227 	struct rcu_head		rcu;
228 };
229 
230 /*
231  * kernfs_syscall_ops may be specified on kernfs_create_root() to support
232  * syscalls.  These optional callbacks are invoked on the matching syscalls
233  * and can perform any kernfs operations which don't necessarily have to be
234  * the exact operation requested.  An active reference is held for each
235  * kernfs_node parameter.
236  */
237 struct kernfs_syscall_ops {
238 	int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
239 
240 	int (*mkdir)(struct kernfs_node *parent, const char *name,
241 		     umode_t mode);
242 	int (*rmdir)(struct kernfs_node *kn);
243 	int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
244 		      const char *new_name);
245 	int (*show_path)(struct seq_file *sf, struct kernfs_node *kn,
246 			 struct kernfs_root *root);
247 };
248 
249 struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root);
250 
251 struct kernfs_open_file {
252 	/* published fields */
253 	struct kernfs_node	*kn;
254 	struct file		*file;
255 	struct seq_file		*seq_file;
256 	void			*priv;
257 
258 	/* private fields, do not use outside kernfs proper */
259 	struct mutex		mutex;
260 	struct mutex		prealloc_mutex;
261 	int			event;
262 	struct list_head	list;
263 	char			*prealloc_buf;
264 
265 	size_t			atomic_write_len;
266 	bool			mmapped:1;
267 	bool			released:1;
268 	const struct vm_operations_struct *vm_ops;
269 };
270 
271 struct kernfs_ops {
272 	/*
273 	 * Optional open/release methods.  Both are called with
274 	 * @of->seq_file populated.
275 	 */
276 	int (*open)(struct kernfs_open_file *of);
277 	void (*release)(struct kernfs_open_file *of);
278 
279 	/*
280 	 * Read is handled by either seq_file or raw_read().
281 	 *
282 	 * If seq_show() is present, seq_file path is active.  Other seq
283 	 * operations are optional and if not implemented, the behavior is
284 	 * equivalent to single_open().  @sf->private points to the
285 	 * associated kernfs_open_file.
286 	 *
287 	 * read() is bounced through kernel buffer and a read larger than
288 	 * PAGE_SIZE results in partial operation of PAGE_SIZE.
289 	 */
290 	int (*seq_show)(struct seq_file *sf, void *v);
291 
292 	void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
293 	void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
294 	void (*seq_stop)(struct seq_file *sf, void *v);
295 
296 	ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
297 			loff_t off);
298 
299 	/*
300 	 * write() is bounced through kernel buffer.  If atomic_write_len
301 	 * is not set, a write larger than PAGE_SIZE results in partial
302 	 * operations of PAGE_SIZE chunks.  If atomic_write_len is set,
303 	 * writes upto the specified size are executed atomically but
304 	 * larger ones are rejected with -E2BIG.
305 	 */
306 	size_t atomic_write_len;
307 	/*
308 	 * "prealloc" causes a buffer to be allocated at open for
309 	 * all read/write requests.  As ->seq_show uses seq_read()
310 	 * which does its own allocation, it is incompatible with
311 	 * ->prealloc.  Provide ->read and ->write with ->prealloc.
312 	 */
313 	bool prealloc;
314 	ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
315 			 loff_t off);
316 
317 	__poll_t (*poll)(struct kernfs_open_file *of,
318 			 struct poll_table_struct *pt);
319 
320 	int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
321 };
322 
323 /*
324  * The kernfs superblock creation/mount parameter context.
325  */
326 struct kernfs_fs_context {
327 	struct kernfs_root	*root;		/* Root of the hierarchy being mounted */
328 	void			*ns_tag;	/* Namespace tag of the mount (or NULL) */
329 	unsigned long		magic;		/* File system specific magic number */
330 
331 	/* The following are set/used by kernfs_mount() */
332 	bool			new_sb_created;	/* Set to T if we allocated a new sb */
333 };
334 
335 #ifdef CONFIG_KERNFS
336 
kernfs_type(struct kernfs_node * kn)337 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
338 {
339 	return kn->flags & KERNFS_TYPE_MASK;
340 }
341 
kernfs_id_ino(u64 id)342 static inline ino_t kernfs_id_ino(u64 id)
343 {
344 	/* id is ino if ino_t is 64bit; otherwise, low 32bits */
345 	if (sizeof(ino_t) >= sizeof(u64))
346 		return id;
347 	else
348 		return (u32)id;
349 }
350 
kernfs_id_gen(u64 id)351 static inline u32 kernfs_id_gen(u64 id)
352 {
353 	/* gen is fixed at 1 if ino_t is 64bit; otherwise, high 32bits */
354 	if (sizeof(ino_t) >= sizeof(u64))
355 		return 1;
356 	else
357 		return id >> 32;
358 }
359 
kernfs_ino(struct kernfs_node * kn)360 static inline ino_t kernfs_ino(struct kernfs_node *kn)
361 {
362 	return kernfs_id_ino(kn->id);
363 }
364 
kernfs_gen(struct kernfs_node * kn)365 static inline ino_t kernfs_gen(struct kernfs_node *kn)
366 {
367 	return kernfs_id_gen(kn->id);
368 }
369 
370 /**
371  * kernfs_enable_ns - enable namespace under a directory
372  * @kn: directory of interest, should be empty
373  *
374  * This is to be called right after @kn is created to enable namespace
375  * under it.  All children of @kn must have non-NULL namespace tags and
376  * only the ones which match the super_block's tag will be visible.
377  */
kernfs_enable_ns(struct kernfs_node * kn)378 static inline void kernfs_enable_ns(struct kernfs_node *kn)
379 {
380 	WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
381 	WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
382 	kn->flags |= KERNFS_NS;
383 }
384 
385 /**
386  * kernfs_ns_enabled - test whether namespace is enabled
387  * @kn: the node to test
388  *
389  * Test whether namespace filtering is enabled for the children of @ns.
390  */
kernfs_ns_enabled(struct kernfs_node * kn)391 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
392 {
393 	return kn->flags & KERNFS_NS;
394 }
395 
396 int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen);
397 int kernfs_path_from_node(struct kernfs_node *root_kn, struct kernfs_node *kn,
398 			  char *buf, size_t buflen);
399 void pr_cont_kernfs_name(struct kernfs_node *kn);
400 void pr_cont_kernfs_path(struct kernfs_node *kn);
401 struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn);
402 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
403 					   const char *name, const void *ns);
404 struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
405 					   const char *path, const void *ns);
406 void kernfs_get(struct kernfs_node *kn);
407 void kernfs_put(struct kernfs_node *kn);
408 
409 struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry);
410 struct kernfs_root *kernfs_root_from_sb(struct super_block *sb);
411 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
412 
413 struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
414 				  struct super_block *sb);
415 struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
416 				       unsigned int flags, void *priv);
417 void kernfs_destroy_root(struct kernfs_root *root);
418 
419 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
420 					 const char *name, umode_t mode,
421 					 kuid_t uid, kgid_t gid,
422 					 void *priv, const void *ns);
423 struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
424 					    const char *name);
425 struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
426 					 const char *name, umode_t mode,
427 					 kuid_t uid, kgid_t gid,
428 					 loff_t size,
429 					 const struct kernfs_ops *ops,
430 					 void *priv, const void *ns,
431 					 struct lock_class_key *key);
432 struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
433 				       const char *name,
434 				       struct kernfs_node *target);
435 void kernfs_activate(struct kernfs_node *kn);
436 void kernfs_show(struct kernfs_node *kn, bool show);
437 void kernfs_remove(struct kernfs_node *kn);
438 void kernfs_break_active_protection(struct kernfs_node *kn);
439 void kernfs_unbreak_active_protection(struct kernfs_node *kn);
440 bool kernfs_remove_self(struct kernfs_node *kn);
441 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
442 			     const void *ns);
443 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
444 		     const char *new_name, const void *new_ns);
445 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
446 __poll_t kernfs_generic_poll(struct kernfs_open_file *of,
447 			     struct poll_table_struct *pt);
448 void kernfs_notify(struct kernfs_node *kn);
449 
450 int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
451 		     void *value, size_t size);
452 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
453 		     const void *value, size_t size, int flags);
454 
455 const void *kernfs_super_ns(struct super_block *sb);
456 int kernfs_get_tree(struct fs_context *fc);
457 void kernfs_free_fs_context(struct fs_context *fc);
458 void kernfs_kill_sb(struct super_block *sb);
459 
460 void kernfs_init(void);
461 
462 struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
463 						   u64 id);
464 #else	/* CONFIG_KERNFS */
465 
kernfs_type(struct kernfs_node * kn)466 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
467 { return 0; }	/* whatever */
468 
kernfs_enable_ns(struct kernfs_node * kn)469 static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
470 
kernfs_ns_enabled(struct kernfs_node * kn)471 static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
472 { return false; }
473 
kernfs_name(struct kernfs_node * kn,char * buf,size_t buflen)474 static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
475 { return -ENOSYS; }
476 
kernfs_path_from_node(struct kernfs_node * root_kn,struct kernfs_node * kn,char * buf,size_t buflen)477 static inline int kernfs_path_from_node(struct kernfs_node *root_kn,
478 					struct kernfs_node *kn,
479 					char *buf, size_t buflen)
480 { return -ENOSYS; }
481 
pr_cont_kernfs_name(struct kernfs_node * kn)482 static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { }
pr_cont_kernfs_path(struct kernfs_node * kn)483 static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { }
484 
kernfs_get_parent(struct kernfs_node * kn)485 static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
486 { return NULL; }
487 
488 static inline struct kernfs_node *
kernfs_find_and_get_ns(struct kernfs_node * parent,const char * name,const void * ns)489 kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
490 		       const void *ns)
491 { return NULL; }
492 static inline struct kernfs_node *
kernfs_walk_and_get_ns(struct kernfs_node * parent,const char * path,const void * ns)493 kernfs_walk_and_get_ns(struct kernfs_node *parent, const char *path,
494 		       const void *ns)
495 { return NULL; }
496 
kernfs_get(struct kernfs_node * kn)497 static inline void kernfs_get(struct kernfs_node *kn) { }
kernfs_put(struct kernfs_node * kn)498 static inline void kernfs_put(struct kernfs_node *kn) { }
499 
kernfs_node_from_dentry(struct dentry * dentry)500 static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
501 { return NULL; }
502 
kernfs_root_from_sb(struct super_block * sb)503 static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
504 { return NULL; }
505 
506 static inline struct inode *
kernfs_get_inode(struct super_block * sb,struct kernfs_node * kn)507 kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
508 { return NULL; }
509 
510 static inline struct kernfs_root *
kernfs_create_root(struct kernfs_syscall_ops * scops,unsigned int flags,void * priv)511 kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
512 		   void *priv)
513 { return ERR_PTR(-ENOSYS); }
514 
kernfs_destroy_root(struct kernfs_root * root)515 static inline void kernfs_destroy_root(struct kernfs_root *root) { }
516 
517 static inline struct kernfs_node *
kernfs_create_dir_ns(struct kernfs_node * parent,const char * name,umode_t mode,kuid_t uid,kgid_t gid,void * priv,const void * ns)518 kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
519 		     umode_t mode, kuid_t uid, kgid_t gid,
520 		     void *priv, const void *ns)
521 { return ERR_PTR(-ENOSYS); }
522 
523 static inline struct kernfs_node *
__kernfs_create_file(struct kernfs_node * parent,const char * name,umode_t mode,kuid_t uid,kgid_t gid,loff_t size,const struct kernfs_ops * ops,void * priv,const void * ns,struct lock_class_key * key)524 __kernfs_create_file(struct kernfs_node *parent, const char *name,
525 		     umode_t mode, kuid_t uid, kgid_t gid,
526 		     loff_t size, const struct kernfs_ops *ops,
527 		     void *priv, const void *ns, struct lock_class_key *key)
528 { return ERR_PTR(-ENOSYS); }
529 
530 static inline struct kernfs_node *
kernfs_create_link(struct kernfs_node * parent,const char * name,struct kernfs_node * target)531 kernfs_create_link(struct kernfs_node *parent, const char *name,
532 		   struct kernfs_node *target)
533 { return ERR_PTR(-ENOSYS); }
534 
kernfs_activate(struct kernfs_node * kn)535 static inline void kernfs_activate(struct kernfs_node *kn) { }
536 
kernfs_remove(struct kernfs_node * kn)537 static inline void kernfs_remove(struct kernfs_node *kn) { }
538 
kernfs_remove_self(struct kernfs_node * kn)539 static inline bool kernfs_remove_self(struct kernfs_node *kn)
540 { return false; }
541 
kernfs_remove_by_name_ns(struct kernfs_node * kn,const char * name,const void * ns)542 static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
543 					   const char *name, const void *ns)
544 { return -ENOSYS; }
545 
kernfs_rename_ns(struct kernfs_node * kn,struct kernfs_node * new_parent,const char * new_name,const void * new_ns)546 static inline int kernfs_rename_ns(struct kernfs_node *kn,
547 				   struct kernfs_node *new_parent,
548 				   const char *new_name, const void *new_ns)
549 { return -ENOSYS; }
550 
kernfs_setattr(struct kernfs_node * kn,const struct iattr * iattr)551 static inline int kernfs_setattr(struct kernfs_node *kn,
552 				 const struct iattr *iattr)
553 { return -ENOSYS; }
554 
kernfs_generic_poll(struct kernfs_open_file * of,struct poll_table_struct * pt)555 static inline __poll_t kernfs_generic_poll(struct kernfs_open_file *of,
556 					   struct poll_table_struct *pt)
557 { return -ENOSYS; }
558 
kernfs_notify(struct kernfs_node * kn)559 static inline void kernfs_notify(struct kernfs_node *kn) { }
560 
kernfs_xattr_get(struct kernfs_node * kn,const char * name,void * value,size_t size)561 static inline int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
562 				   void *value, size_t size)
563 { return -ENOSYS; }
564 
kernfs_xattr_set(struct kernfs_node * kn,const char * name,const void * value,size_t size,int flags)565 static inline int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
566 				   const void *value, size_t size, int flags)
567 { return -ENOSYS; }
568 
kernfs_super_ns(struct super_block * sb)569 static inline const void *kernfs_super_ns(struct super_block *sb)
570 { return NULL; }
571 
kernfs_get_tree(struct fs_context * fc)572 static inline int kernfs_get_tree(struct fs_context *fc)
573 { return -ENOSYS; }
574 
kernfs_free_fs_context(struct fs_context * fc)575 static inline void kernfs_free_fs_context(struct fs_context *fc) { }
576 
kernfs_kill_sb(struct super_block * sb)577 static inline void kernfs_kill_sb(struct super_block *sb) { }
578 
kernfs_init(void)579 static inline void kernfs_init(void) { }
580 
581 #endif	/* CONFIG_KERNFS */
582 
583 /**
584  * kernfs_path - build full path of a given node
585  * @kn: kernfs_node of interest
586  * @buf: buffer to copy @kn's name into
587  * @buflen: size of @buf
588  *
589  * If @kn is NULL result will be "(null)".
590  *
591  * Returns the length of the full path.  If the full length is equal to or
592  * greater than @buflen, @buf contains the truncated path with the trailing
593  * '\0'.  On error, -errno is returned.
594  */
kernfs_path(struct kernfs_node * kn,char * buf,size_t buflen)595 static inline int kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
596 {
597 	return kernfs_path_from_node(kn, NULL, buf, buflen);
598 }
599 
600 static inline struct kernfs_node *
kernfs_find_and_get(struct kernfs_node * kn,const char * name)601 kernfs_find_and_get(struct kernfs_node *kn, const char *name)
602 {
603 	return kernfs_find_and_get_ns(kn, name, NULL);
604 }
605 
606 static inline struct kernfs_node *
kernfs_walk_and_get(struct kernfs_node * kn,const char * path)607 kernfs_walk_and_get(struct kernfs_node *kn, const char *path)
608 {
609 	return kernfs_walk_and_get_ns(kn, path, NULL);
610 }
611 
612 static inline struct kernfs_node *
kernfs_create_dir(struct kernfs_node * parent,const char * name,umode_t mode,void * priv)613 kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
614 		  void *priv)
615 {
616 	return kernfs_create_dir_ns(parent, name, mode,
617 				    GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
618 				    priv, NULL);
619 }
620 
kernfs_remove_by_name(struct kernfs_node * parent,const char * name)621 static inline int kernfs_remove_by_name(struct kernfs_node *parent,
622 					const char *name)
623 {
624 	return kernfs_remove_by_name_ns(parent, name, NULL);
625 }
626 
kernfs_rename(struct kernfs_node * kn,struct kernfs_node * new_parent,const char * new_name)627 static inline int kernfs_rename(struct kernfs_node *kn,
628 				struct kernfs_node *new_parent,
629 				const char *new_name)
630 {
631 	return kernfs_rename_ns(kn, new_parent, new_name, NULL);
632 }
633 
634 #endif	/* __LINUX_KERNFS_H */
635