2 * fs/sysfs/dir.c - sysfs core and dir operation implementation
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 * This file is released under the GPLv2.
10 * Please see Documentation/filesystems/sysfs.txt for more information.
16 #include <linux/mount.h>
17 #include <linux/module.h>
18 #include <linux/kobject.h>
19 #include <linux/namei.h>
20 #include <linux/idr.h>
21 #include <linux/completion.h>
22 #include <linux/mutex.h>
23 #include <linux/slab.h>
24 #include <linux/security.h>
27 DEFINE_MUTEX(sysfs_mutex
);
28 DEFINE_SPINLOCK(sysfs_assoc_lock
);
30 static DEFINE_SPINLOCK(sysfs_ino_lock
);
31 static DEFINE_IDA(sysfs_ino_ida
);
34 * sysfs_link_sibling - link sysfs_dirent into sibling list
35 * @sd: sysfs_dirent of interest
37 * Link @sd into its sibling list which starts from
38 * sd->s_parent->s_dir.children.
41 * mutex_lock(sysfs_mutex)
43 static void sysfs_link_sibling(struct sysfs_dirent
*sd
)
45 struct sysfs_dirent
*parent_sd
= sd
->s_parent
;
46 struct sysfs_dirent
**pos
;
48 BUG_ON(sd
->s_sibling
);
50 /* Store directory entries in order by ino. This allows
51 * readdir to properly restart without having to add a
52 * cursor into the s_dir.children list.
54 for (pos
= &parent_sd
->s_dir
.children
; *pos
; pos
= &(*pos
)->s_sibling
) {
55 if (sd
->s_ino
< (*pos
)->s_ino
)
63 * sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
64 * @sd: sysfs_dirent of interest
66 * Unlink @sd from its sibling list which starts from
67 * sd->s_parent->s_dir.children.
70 * mutex_lock(sysfs_mutex)
72 static void sysfs_unlink_sibling(struct sysfs_dirent
*sd
)
74 struct sysfs_dirent
**pos
;
76 for (pos
= &sd
->s_parent
->s_dir
.children
; *pos
;
77 pos
= &(*pos
)->s_sibling
) {
87 * sysfs_get_active - get an active reference to sysfs_dirent
88 * @sd: sysfs_dirent to get an active reference to
90 * Get an active reference of @sd. This function is noop if @sd
94 * Pointer to @sd on success, NULL on failure.
96 static struct sysfs_dirent
*sysfs_get_active(struct sysfs_dirent
*sd
)
104 v
= atomic_read(&sd
->s_active
);
108 t
= atomic_cmpxchg(&sd
->s_active
, v
, v
+ 1);
109 if (likely(t
== v
)) {
110 rwsem_acquire_read(&sd
->dep_map
, 0, 1, _RET_IP_
);
121 * sysfs_put_active - put an active reference to sysfs_dirent
122 * @sd: sysfs_dirent to put an active reference to
124 * Put an active reference to @sd. This function is noop if @sd
127 static void sysfs_put_active(struct sysfs_dirent
*sd
)
129 struct completion
*cmpl
;
135 rwsem_release(&sd
->dep_map
, 1, _RET_IP_
);
136 v
= atomic_dec_return(&sd
->s_active
);
137 if (likely(v
!= SD_DEACTIVATED_BIAS
))
140 /* atomic_dec_return() is a mb(), we'll always see the updated
143 cmpl
= (void *)sd
->s_sibling
;
148 * sysfs_get_active_two - get active references to sysfs_dirent and parent
149 * @sd: sysfs_dirent of interest
151 * Get active reference to @sd and its parent. Parent's active
152 * reference is grabbed first. This function is noop if @sd is
156 * Pointer to @sd on success, NULL on failure.
158 struct sysfs_dirent
*sysfs_get_active_two(struct sysfs_dirent
*sd
)
161 if (sd
->s_parent
&& unlikely(!sysfs_get_active(sd
->s_parent
)))
163 if (unlikely(!sysfs_get_active(sd
))) {
164 sysfs_put_active(sd
->s_parent
);
172 * sysfs_put_active_two - put active references to sysfs_dirent and parent
173 * @sd: sysfs_dirent of interest
175 * Put active references to @sd and its parent. This function is
176 * noop if @sd is NULL.
178 void sysfs_put_active_two(struct sysfs_dirent
*sd
)
181 sysfs_put_active(sd
);
182 sysfs_put_active(sd
->s_parent
);
187 * sysfs_deactivate - deactivate sysfs_dirent
188 * @sd: sysfs_dirent to deactivate
190 * Deny new active references and drain existing ones.
192 static void sysfs_deactivate(struct sysfs_dirent
*sd
)
194 DECLARE_COMPLETION_ONSTACK(wait
);
197 BUG_ON(sd
->s_sibling
|| !(sd
->s_flags
& SYSFS_FLAG_REMOVED
));
198 sd
->s_sibling
= (void *)&wait
;
200 rwsem_acquire(&sd
->dep_map
, 0, 0, _RET_IP_
);
201 /* atomic_add_return() is a mb(), put_active() will always see
202 * the updated sd->s_sibling.
204 v
= atomic_add_return(SD_DEACTIVATED_BIAS
, &sd
->s_active
);
206 if (v
!= SD_DEACTIVATED_BIAS
) {
207 lock_contended(&sd
->dep_map
, _RET_IP_
);
208 wait_for_completion(&wait
);
211 sd
->s_sibling
= NULL
;
213 lock_acquired(&sd
->dep_map
, _RET_IP_
);
214 rwsem_release(&sd
->dep_map
, 1, _RET_IP_
);
217 static int sysfs_alloc_ino(ino_t
*pino
)
222 spin_lock(&sysfs_ino_lock
);
223 rc
= ida_get_new_above(&sysfs_ino_ida
, 2, &ino
);
224 spin_unlock(&sysfs_ino_lock
);
227 if (ida_pre_get(&sysfs_ino_ida
, GFP_KERNEL
))
236 static void sysfs_free_ino(ino_t ino
)
238 spin_lock(&sysfs_ino_lock
);
239 ida_remove(&sysfs_ino_ida
, ino
);
240 spin_unlock(&sysfs_ino_lock
);
243 void release_sysfs_dirent(struct sysfs_dirent
* sd
)
245 struct sysfs_dirent
*parent_sd
;
248 /* Moving/renaming is always done while holding reference.
249 * sd->s_parent won't change beneath us.
251 parent_sd
= sd
->s_parent
;
253 if (sysfs_type(sd
) == SYSFS_KOBJ_LINK
)
254 sysfs_put(sd
->s_symlink
.target_sd
);
255 if (sysfs_type(sd
) & SYSFS_COPY_NAME
)
257 if (sd
->s_iattr
&& sd
->s_iattr
->ia_secdata
)
258 security_release_secctx(sd
->s_iattr
->ia_secdata
,
259 sd
->s_iattr
->ia_secdata_len
);
261 sysfs_free_ino(sd
->s_ino
);
262 kmem_cache_free(sysfs_dir_cachep
, sd
);
265 if (sd
&& atomic_dec_and_test(&sd
->s_count
))
269 static int sysfs_dentry_delete(struct dentry
*dentry
)
271 struct sysfs_dirent
*sd
= dentry
->d_fsdata
;
272 return !!(sd
->s_flags
& SYSFS_FLAG_REMOVED
);
275 static int sysfs_dentry_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
277 struct sysfs_dirent
*sd
= dentry
->d_fsdata
;
280 mutex_lock(&sysfs_mutex
);
282 /* The sysfs dirent has been deleted */
283 if (sd
->s_flags
& SYSFS_FLAG_REMOVED
)
286 /* The sysfs dirent has been moved? */
287 if (dentry
->d_parent
->d_fsdata
!= sd
->s_parent
)
290 /* The sysfs dirent has been renamed */
291 if (strcmp(dentry
->d_name
.name
, sd
->s_name
) != 0)
294 mutex_unlock(&sysfs_mutex
);
298 /* Remove the dentry from the dcache hashes.
299 * If this is a deleted dentry we use d_drop instead of d_delete
300 * so sysfs doesn't need to cope with negative dentries.
302 * If this is a dentry that has simply been renamed we
303 * use d_drop to remove it from the dcache lookup on its
304 * old parent. If this dentry persists later when a lookup
305 * is performed at its new name the dentry will be readded
306 * to the dcache hashes.
308 is_dir
= (sysfs_type(sd
) == SYSFS_DIR
);
309 mutex_unlock(&sysfs_mutex
);
311 /* If we have submounts we must allow the vfs caches
312 * to lie about the state of the filesystem to prevent
313 * leaks and other nasty things.
315 if (have_submounts(dentry
))
317 shrink_dcache_parent(dentry
);
323 static void sysfs_dentry_iput(struct dentry
*dentry
, struct inode
*inode
)
325 struct sysfs_dirent
* sd
= dentry
->d_fsdata
;
331 static const struct dentry_operations sysfs_dentry_ops
= {
332 .d_revalidate
= sysfs_dentry_revalidate
,
333 .d_delete
= sysfs_dentry_delete
,
334 .d_iput
= sysfs_dentry_iput
,
337 struct sysfs_dirent
*sysfs_new_dirent(const char *name
, umode_t mode
, int type
)
339 char *dup_name
= NULL
;
340 struct sysfs_dirent
*sd
;
342 if (type
& SYSFS_COPY_NAME
) {
343 name
= dup_name
= kstrdup(name
, GFP_KERNEL
);
348 sd
= kmem_cache_zalloc(sysfs_dir_cachep
, GFP_KERNEL
);
352 if (sysfs_alloc_ino(&sd
->s_ino
))
355 atomic_set(&sd
->s_count
, 1);
356 atomic_set(&sd
->s_active
, 0);
357 sysfs_dirent_init_lockdep(sd
);
366 kmem_cache_free(sysfs_dir_cachep
, sd
);
373 * sysfs_addrm_start - prepare for sysfs_dirent add/remove
374 * @acxt: pointer to sysfs_addrm_cxt to be used
375 * @parent_sd: parent sysfs_dirent
377 * This function is called when the caller is about to add or
378 * remove sysfs_dirent under @parent_sd. This function acquires
379 * sysfs_mutex. @acxt is used to keep and pass context to
380 * other addrm functions.
383 * Kernel thread context (may sleep). sysfs_mutex is locked on
386 void sysfs_addrm_start(struct sysfs_addrm_cxt
*acxt
,
387 struct sysfs_dirent
*parent_sd
)
389 memset(acxt
, 0, sizeof(*acxt
));
390 acxt
->parent_sd
= parent_sd
;
392 mutex_lock(&sysfs_mutex
);
396 * __sysfs_add_one - add sysfs_dirent to parent without warning
397 * @acxt: addrm context to use
398 * @sd: sysfs_dirent to be added
400 * Get @acxt->parent_sd and set sd->s_parent to it and increment
401 * nlink of parent inode if @sd is a directory and link into the
402 * children list of the parent.
404 * This function should be called between calls to
405 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
406 * passed the same @acxt as passed to sysfs_addrm_start().
409 * Determined by sysfs_addrm_start().
412 * 0 on success, -EEXIST if entry with the given name already
415 int __sysfs_add_one(struct sysfs_addrm_cxt
*acxt
, struct sysfs_dirent
*sd
)
417 struct sysfs_inode_attrs
*ps_iattr
;
419 if (sysfs_find_dirent(acxt
->parent_sd
, sd
->s_name
))
422 sd
->s_parent
= sysfs_get(acxt
->parent_sd
);
424 sysfs_link_sibling(sd
);
426 /* Update timestamps on the parent */
427 ps_iattr
= acxt
->parent_sd
->s_iattr
;
429 struct iattr
*ps_iattrs
= &ps_iattr
->ia_iattr
;
430 ps_iattrs
->ia_ctime
= ps_iattrs
->ia_mtime
= CURRENT_TIME
;
437 * sysfs_pathname - return full path to sysfs dirent
438 * @sd: sysfs_dirent whose path we want
439 * @path: caller allocated buffer
441 * Gives the name "/" to the sysfs_root entry; any path returned
442 * is relative to wherever sysfs is mounted.
444 * XXX: does no error checking on @path size
446 static char *sysfs_pathname(struct sysfs_dirent
*sd
, char *path
)
449 sysfs_pathname(sd
->s_parent
, path
);
452 strcat(path
, sd
->s_name
);
457 * sysfs_add_one - add sysfs_dirent to parent
458 * @acxt: addrm context to use
459 * @sd: sysfs_dirent to be added
461 * Get @acxt->parent_sd and set sd->s_parent to it and increment
462 * nlink of parent inode if @sd is a directory and link into the
463 * children list of the parent.
465 * This function should be called between calls to
466 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
467 * passed the same @acxt as passed to sysfs_addrm_start().
470 * Determined by sysfs_addrm_start().
473 * 0 on success, -EEXIST if entry with the given name already
476 int sysfs_add_one(struct sysfs_addrm_cxt
*acxt
, struct sysfs_dirent
*sd
)
480 ret
= __sysfs_add_one(acxt
, sd
);
481 if (ret
== -EEXIST
) {
482 char *path
= kzalloc(PATH_MAX
, GFP_KERNEL
);
484 "sysfs: cannot create duplicate filename '%s'\n",
485 (path
== NULL
) ? sd
->s_name
:
486 strcat(strcat(sysfs_pathname(acxt
->parent_sd
, path
), "/"),
495 * sysfs_remove_one - remove sysfs_dirent from parent
496 * @acxt: addrm context to use
497 * @sd: sysfs_dirent to be removed
499 * Mark @sd removed and drop nlink of parent inode if @sd is a
500 * directory. @sd is unlinked from the children list.
502 * This function should be called between calls to
503 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
504 * passed the same @acxt as passed to sysfs_addrm_start().
507 * Determined by sysfs_addrm_start().
509 void sysfs_remove_one(struct sysfs_addrm_cxt
*acxt
, struct sysfs_dirent
*sd
)
511 struct sysfs_inode_attrs
*ps_iattr
;
513 BUG_ON(sd
->s_flags
& SYSFS_FLAG_REMOVED
);
515 sysfs_unlink_sibling(sd
);
517 /* Update timestamps on the parent */
518 ps_iattr
= acxt
->parent_sd
->s_iattr
;
520 struct iattr
*ps_iattrs
= &ps_iattr
->ia_iattr
;
521 ps_iattrs
->ia_ctime
= ps_iattrs
->ia_mtime
= CURRENT_TIME
;
524 sd
->s_flags
|= SYSFS_FLAG_REMOVED
;
525 sd
->s_sibling
= acxt
->removed
;
530 * sysfs_addrm_finish - finish up sysfs_dirent add/remove
531 * @acxt: addrm context to finish up
533 * Finish up sysfs_dirent add/remove. Resources acquired by
534 * sysfs_addrm_start() are released and removed sysfs_dirents are
538 * sysfs_mutex is released.
540 void sysfs_addrm_finish(struct sysfs_addrm_cxt
*acxt
)
542 /* release resources acquired by sysfs_addrm_start() */
543 mutex_unlock(&sysfs_mutex
);
545 /* kill removed sysfs_dirents */
546 while (acxt
->removed
) {
547 struct sysfs_dirent
*sd
= acxt
->removed
;
549 acxt
->removed
= sd
->s_sibling
;
550 sd
->s_sibling
= NULL
;
552 sysfs_deactivate(sd
);
559 * sysfs_find_dirent - find sysfs_dirent with the given name
560 * @parent_sd: sysfs_dirent to search under
561 * @name: name to look for
563 * Look for sysfs_dirent with name @name under @parent_sd.
566 * mutex_lock(sysfs_mutex)
569 * Pointer to sysfs_dirent if found, NULL if not.
571 struct sysfs_dirent
*sysfs_find_dirent(struct sysfs_dirent
*parent_sd
,
572 const unsigned char *name
)
574 struct sysfs_dirent
*sd
;
576 for (sd
= parent_sd
->s_dir
.children
; sd
; sd
= sd
->s_sibling
)
577 if (!strcmp(sd
->s_name
, name
))
583 * sysfs_get_dirent - find and get sysfs_dirent with the given name
584 * @parent_sd: sysfs_dirent to search under
585 * @name: name to look for
587 * Look for sysfs_dirent with name @name under @parent_sd and get
591 * Kernel thread context (may sleep). Grabs sysfs_mutex.
594 * Pointer to sysfs_dirent if found, NULL if not.
596 struct sysfs_dirent
*sysfs_get_dirent(struct sysfs_dirent
*parent_sd
,
597 const unsigned char *name
)
599 struct sysfs_dirent
*sd
;
601 mutex_lock(&sysfs_mutex
);
602 sd
= sysfs_find_dirent(parent_sd
, name
);
604 mutex_unlock(&sysfs_mutex
);
608 EXPORT_SYMBOL_GPL(sysfs_get_dirent
);
610 static int create_dir(struct kobject
*kobj
, struct sysfs_dirent
*parent_sd
,
611 const char *name
, struct sysfs_dirent
**p_sd
)
613 umode_t mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
614 struct sysfs_addrm_cxt acxt
;
615 struct sysfs_dirent
*sd
;
619 sd
= sysfs_new_dirent(name
, mode
, SYSFS_DIR
);
622 sd
->s_dir
.kobj
= kobj
;
625 sysfs_addrm_start(&acxt
, parent_sd
);
626 rc
= sysfs_add_one(&acxt
, sd
);
627 sysfs_addrm_finish(&acxt
);
637 int sysfs_create_subdir(struct kobject
*kobj
, const char *name
,
638 struct sysfs_dirent
**p_sd
)
640 return create_dir(kobj
, kobj
->sd
, name
, p_sd
);
644 * sysfs_create_dir - create a directory for an object.
645 * @kobj: object we're creating directory for.
647 int sysfs_create_dir(struct kobject
* kobj
)
649 struct sysfs_dirent
*parent_sd
, *sd
;
655 parent_sd
= kobj
->parent
->sd
;
657 parent_sd
= &sysfs_root
;
659 error
= create_dir(kobj
, parent_sd
, kobject_name(kobj
), &sd
);
665 static struct dentry
* sysfs_lookup(struct inode
*dir
, struct dentry
*dentry
,
666 struct nameidata
*nd
)
668 struct dentry
*ret
= NULL
;
669 struct sysfs_dirent
*parent_sd
= dentry
->d_parent
->d_fsdata
;
670 struct sysfs_dirent
*sd
;
673 mutex_lock(&sysfs_mutex
);
675 sd
= sysfs_find_dirent(parent_sd
, dentry
->d_name
.name
);
679 ret
= ERR_PTR(-ENOENT
);
683 /* attach dentry and inode */
684 inode
= sysfs_get_inode(sd
);
686 ret
= ERR_PTR(-ENOMEM
);
690 /* instantiate and hash dentry */
691 ret
= d_find_alias(inode
);
693 dentry
->d_op
= &sysfs_dentry_ops
;
694 dentry
->d_fsdata
= sysfs_get(sd
);
695 d_add(dentry
, inode
);
702 mutex_unlock(&sysfs_mutex
);
706 const struct inode_operations sysfs_dir_inode_operations
= {
707 .lookup
= sysfs_lookup
,
708 .permission
= sysfs_permission
,
709 .setattr
= sysfs_setattr
,
710 .getattr
= sysfs_getattr
,
711 .setxattr
= sysfs_setxattr
,
714 static void remove_dir(struct sysfs_dirent
*sd
)
716 struct sysfs_addrm_cxt acxt
;
718 sysfs_addrm_start(&acxt
, sd
->s_parent
);
719 sysfs_remove_one(&acxt
, sd
);
720 sysfs_addrm_finish(&acxt
);
723 void sysfs_remove_subdir(struct sysfs_dirent
*sd
)
729 static void __sysfs_remove_dir(struct sysfs_dirent
*dir_sd
)
731 struct sysfs_addrm_cxt acxt
;
732 struct sysfs_dirent
**pos
;
737 pr_debug("sysfs %s: removing dir\n", dir_sd
->s_name
);
738 sysfs_addrm_start(&acxt
, dir_sd
);
739 pos
= &dir_sd
->s_dir
.children
;
741 struct sysfs_dirent
*sd
= *pos
;
743 if (sysfs_type(sd
) != SYSFS_DIR
)
744 sysfs_remove_one(&acxt
, sd
);
746 pos
= &(*pos
)->s_sibling
;
748 sysfs_addrm_finish(&acxt
);
754 * sysfs_remove_dir - remove an object's directory.
757 * The only thing special about this is that we remove any files in
758 * the directory before we remove the directory, and we've inlined
759 * what used to be sysfs_rmdir() below, instead of calling separately.
762 void sysfs_remove_dir(struct kobject
* kobj
)
764 struct sysfs_dirent
*sd
= kobj
->sd
;
766 spin_lock(&sysfs_assoc_lock
);
768 spin_unlock(&sysfs_assoc_lock
);
770 __sysfs_remove_dir(sd
);
773 int sysfs_rename(struct sysfs_dirent
*sd
,
774 struct sysfs_dirent
*new_parent_sd
, const char *new_name
)
776 const char *dup_name
= NULL
;
779 mutex_lock(&sysfs_mutex
);
782 if ((sd
->s_parent
== new_parent_sd
) &&
783 (strcmp(sd
->s_name
, new_name
) == 0))
784 goto out
; /* nothing to rename */
787 if (sysfs_find_dirent(new_parent_sd
, new_name
))
790 /* rename sysfs_dirent */
791 if (strcmp(sd
->s_name
, new_name
) != 0) {
793 new_name
= dup_name
= kstrdup(new_name
, GFP_KERNEL
);
797 dup_name
= sd
->s_name
;
798 sd
->s_name
= new_name
;
801 /* Remove from old parent's list and insert into new parent's list. */
802 if (sd
->s_parent
!= new_parent_sd
) {
803 sysfs_unlink_sibling(sd
);
804 sysfs_get(new_parent_sd
);
805 sysfs_put(sd
->s_parent
);
806 sd
->s_parent
= new_parent_sd
;
807 sysfs_link_sibling(sd
);
812 mutex_unlock(&sysfs_mutex
);
817 int sysfs_rename_dir(struct kobject
*kobj
, const char *new_name
)
819 return sysfs_rename(kobj
->sd
, kobj
->sd
->s_parent
, new_name
);
822 int sysfs_move_dir(struct kobject
*kobj
, struct kobject
*new_parent_kobj
)
824 struct sysfs_dirent
*sd
= kobj
->sd
;
825 struct sysfs_dirent
*new_parent_sd
;
827 BUG_ON(!sd
->s_parent
);
828 new_parent_sd
= new_parent_kobj
&& new_parent_kobj
->sd
?
829 new_parent_kobj
->sd
: &sysfs_root
;
831 return sysfs_rename(sd
, new_parent_sd
, sd
->s_name
);
834 /* Relationship between s_mode and the DT_xxx types */
835 static inline unsigned char dt_type(struct sysfs_dirent
*sd
)
837 return (sd
->s_mode
>> 12) & 15;
840 static int sysfs_readdir(struct file
* filp
, void * dirent
, filldir_t filldir
)
842 struct dentry
*dentry
= filp
->f_path
.dentry
;
843 struct sysfs_dirent
* parent_sd
= dentry
->d_fsdata
;
844 struct sysfs_dirent
*pos
;
847 if (filp
->f_pos
== 0) {
848 ino
= parent_sd
->s_ino
;
849 if (filldir(dirent
, ".", 1, filp
->f_pos
, ino
, DT_DIR
) == 0)
852 if (filp
->f_pos
== 1) {
853 if (parent_sd
->s_parent
)
854 ino
= parent_sd
->s_parent
->s_ino
;
856 ino
= parent_sd
->s_ino
;
857 if (filldir(dirent
, "..", 2, filp
->f_pos
, ino
, DT_DIR
) == 0)
860 if ((filp
->f_pos
> 1) && (filp
->f_pos
< INT_MAX
)) {
861 mutex_lock(&sysfs_mutex
);
863 /* Skip the dentries we have already reported */
864 pos
= parent_sd
->s_dir
.children
;
865 while (pos
&& (filp
->f_pos
> pos
->s_ino
))
866 pos
= pos
->s_sibling
;
868 for ( ; pos
; pos
= pos
->s_sibling
) {
874 filp
->f_pos
= ino
= pos
->s_ino
;
876 if (filldir(dirent
, name
, len
, filp
->f_pos
, ino
,
881 filp
->f_pos
= INT_MAX
;
882 mutex_unlock(&sysfs_mutex
);
888 const struct file_operations sysfs_dir_operations
= {
889 .read
= generic_read_dir
,
890 .readdir
= sysfs_readdir
,
891 .llseek
= generic_file_llseek
,