2 * dir.c - Operations for sysfs directories.
8 #include <linux/mount.h>
9 #include <linux/module.h>
10 #include <linux/kobject.h>
11 #include <linux/namei.h>
12 #include <linux/idr.h>
13 #include <linux/completion.h>
14 #include <linux/mutex.h>
17 DEFINE_MUTEX(sysfs_mutex);
18 spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
20 static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
21 static DEFINE_IDA(sysfs_ino_ida);
24 * sysfs_link_sibling - link sysfs_dirent into sibling list
25 * @sd: sysfs_dirent of interest
27 * Link @sd into its sibling list which starts from
28 * sd->s_parent->s_children.
31 * mutex_lock(sysfs_mutex)
33 static void sysfs_link_sibling(struct sysfs_dirent *sd)
35 struct sysfs_dirent *parent_sd = sd->s_parent;
36 struct sysfs_dirent **pos;
38 BUG_ON(sd->s_sibling);
40 /* Store directory entries in order by ino. This allows
41 * readdir to properly restart without having to add a
42 * cursor into the s_children list.
44 for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
45 if (sd->s_ino < (*pos)->s_ino)
53 * sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
54 * @sd: sysfs_dirent of interest
56 * Unlink @sd from its sibling list which starts from
57 * sd->s_parent->s_children.
60 * mutex_lock(sysfs_mutex)
62 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
64 struct sysfs_dirent **pos;
66 for (pos = &sd->s_parent->s_children; *pos; pos = &(*pos)->s_sibling) {
76 * sysfs_get_dentry - get dentry for the given sysfs_dirent
77 * @sd: sysfs_dirent of interest
79 * Get dentry for @sd. Dentry is looked up if currently not
80 * present. This function climbs sysfs_dirent tree till it
81 * reaches a sysfs_dirent with valid dentry attached and descends
82 * down from there looking up dentry for each step.
85 * Kernel thread context (may sleep)
88 * Pointer to found dentry on success, ERR_PTR() value on error.
90 struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
92 struct sysfs_dirent *cur;
93 struct dentry *parent_dentry, *dentry;
96 /* Find the first parent which has valid s_dentry and get the
99 mutex_lock(&sysfs_mutex);
101 spin_lock(&sysfs_assoc_lock);
103 spin_lock(&dcache_lock);
108 while (!cur->s_dentry || !cur->s_dentry->d_inode) {
109 if (cur->s_flags & SYSFS_FLAG_REMOVED) {
110 dentry = ERR_PTR(-ENOENT);
118 dentry = dget_locked(cur->s_dentry);
120 spin_unlock(&dcache_lock);
121 spin_unlock(&sysfs_assoc_lock);
123 /* from the found dentry, look up depth times */
125 /* find and get depth'th ancestor */
126 for (cur = sd, i = 0; cur && i < depth; i++)
129 /* This can happen if tree structure was modified due
130 * to move/rename. Restart.
139 mutex_unlock(&sysfs_mutex);
142 parent_dentry = dentry;
143 mutex_lock(&parent_dentry->d_inode->i_mutex);
144 dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
145 strlen(cur->s_name));
146 mutex_unlock(&parent_dentry->d_inode->i_mutex);
149 if (IS_ERR(dentry)) {
154 mutex_lock(&sysfs_mutex);
155 spin_lock(&sysfs_assoc_lock);
157 /* This, again, can happen if tree structure has
158 * changed and we looked up the wrong thing. Restart.
160 if (cur->s_dentry != dentry) {
166 spin_unlock(&sysfs_assoc_lock);
171 mutex_unlock(&sysfs_mutex);
176 * sysfs_get_active - get an active reference to sysfs_dirent
177 * @sd: sysfs_dirent to get an active reference to
179 * Get an active reference of @sd. This function is noop if @sd
183 * Pointer to @sd on success, NULL on failure.
185 struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
193 v = atomic_read(&sd->s_active);
197 t = atomic_cmpxchg(&sd->s_active, v, v + 1);
208 * sysfs_put_active - put an active reference to sysfs_dirent
209 * @sd: sysfs_dirent to put an active reference to
211 * Put an active reference to @sd. This function is noop if @sd
214 void sysfs_put_active(struct sysfs_dirent *sd)
216 struct completion *cmpl;
222 v = atomic_dec_return(&sd->s_active);
223 if (likely(v != SD_DEACTIVATED_BIAS))
226 /* atomic_dec_return() is a mb(), we'll always see the updated
229 cmpl = (void *)sd->s_sibling;
234 * sysfs_get_active_two - get active references to sysfs_dirent and parent
235 * @sd: sysfs_dirent of interest
237 * Get active reference to @sd and its parent. Parent's active
238 * reference is grabbed first. This function is noop if @sd is
242 * Pointer to @sd on success, NULL on failure.
244 struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
247 if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
249 if (unlikely(!sysfs_get_active(sd))) {
250 sysfs_put_active(sd->s_parent);
258 * sysfs_put_active_two - put active references to sysfs_dirent and parent
259 * @sd: sysfs_dirent of interest
261 * Put active references to @sd and its parent. This function is
262 * noop if @sd is NULL.
264 void sysfs_put_active_two(struct sysfs_dirent *sd)
267 sysfs_put_active(sd);
268 sysfs_put_active(sd->s_parent);
273 * sysfs_deactivate - deactivate sysfs_dirent
274 * @sd: sysfs_dirent to deactivate
276 * Deny new active references and drain existing ones.
278 static void sysfs_deactivate(struct sysfs_dirent *sd)
280 DECLARE_COMPLETION_ONSTACK(wait);
283 BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
284 sd->s_sibling = (void *)&wait;
286 /* atomic_add_return() is a mb(), put_active() will always see
287 * the updated sd->s_sibling.
289 v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
291 if (v != SD_DEACTIVATED_BIAS)
292 wait_for_completion(&wait);
294 sd->s_sibling = NULL;
297 static int sysfs_alloc_ino(ino_t *pino)
302 spin_lock(&sysfs_ino_lock);
303 rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
304 spin_unlock(&sysfs_ino_lock);
307 if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
316 static void sysfs_free_ino(ino_t ino)
318 spin_lock(&sysfs_ino_lock);
319 ida_remove(&sysfs_ino_ida, ino);
320 spin_unlock(&sysfs_ino_lock);
323 void release_sysfs_dirent(struct sysfs_dirent * sd)
325 struct sysfs_dirent *parent_sd;
328 /* Moving/renaming is always done while holding reference.
329 * sd->s_parent won't change beneath us.
331 parent_sd = sd->s_parent;
333 if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
334 sysfs_put(sd->s_elem.symlink.target_sd);
335 if (sysfs_type(sd) & SYSFS_COPY_NAME)
338 sysfs_free_ino(sd->s_ino);
339 kmem_cache_free(sysfs_dir_cachep, sd);
342 if (sd && atomic_dec_and_test(&sd->s_count))
346 static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
348 struct sysfs_dirent * sd = dentry->d_fsdata;
351 /* sd->s_dentry is protected with sysfs_assoc_lock.
352 * This allows sysfs_drop_dentry() to dereference it.
354 spin_lock(&sysfs_assoc_lock);
356 /* The dentry might have been deleted or another
357 * lookup could have happened updating sd->s_dentry to
358 * point the new dentry. Ignore if it isn't pointing
361 if (sd->s_dentry == dentry)
363 spin_unlock(&sysfs_assoc_lock);
369 static struct dentry_operations sysfs_dentry_ops = {
370 .d_iput = sysfs_d_iput,
373 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
375 char *dup_name = NULL;
376 struct sysfs_dirent *sd;
378 if (type & SYSFS_COPY_NAME) {
379 name = dup_name = kstrdup(name, GFP_KERNEL);
384 sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
388 if (sysfs_alloc_ino(&sd->s_ino))
391 atomic_set(&sd->s_count, 1);
392 atomic_set(&sd->s_active, 0);
393 atomic_set(&sd->s_event, 1);
402 kmem_cache_free(sysfs_dir_cachep, sd);
409 * sysfs_attach_dentry - associate sysfs_dirent with dentry
410 * @sd: target sysfs_dirent
411 * @dentry: dentry to associate
413 * Associate @sd with @dentry. This is protected by
414 * sysfs_assoc_lock to avoid race with sysfs_d_iput().
417 * mutex_lock(sysfs_mutex)
419 static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
421 dentry->d_op = &sysfs_dentry_ops;
422 dentry->d_fsdata = sysfs_get(sd);
424 /* protect sd->s_dentry against sysfs_d_iput */
425 spin_lock(&sysfs_assoc_lock);
426 sd->s_dentry = dentry;
427 spin_unlock(&sysfs_assoc_lock);
432 static int sysfs_ilookup_test(struct inode *inode, void *arg)
434 struct sysfs_dirent *sd = arg;
435 return inode->i_ino == sd->s_ino;
439 * sysfs_addrm_start - prepare for sysfs_dirent add/remove
440 * @acxt: pointer to sysfs_addrm_cxt to be used
441 * @parent_sd: parent sysfs_dirent
443 * This function is called when the caller is about to add or
444 * remove sysfs_dirent under @parent_sd. This function acquires
445 * sysfs_mutex, grabs inode for @parent_sd if available and lock
446 * i_mutex of it. @acxt is used to keep and pass context to
447 * other addrm functions.
450 * Kernel thread context (may sleep). sysfs_mutex is locked on
451 * return. i_mutex of parent inode is locked on return if
454 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
455 struct sysfs_dirent *parent_sd)
459 memset(acxt, 0, sizeof(*acxt));
460 acxt->parent_sd = parent_sd;
462 /* Lookup parent inode. inode initialization and I_NEW
463 * clearing are protected by sysfs_mutex. By grabbing it and
464 * looking up with _nowait variant, inode state can be
465 * determined reliably.
467 mutex_lock(&sysfs_mutex);
469 inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
472 if (inode && !(inode->i_state & I_NEW)) {
473 /* parent inode available */
474 acxt->parent_inode = inode;
476 /* sysfs_mutex is below i_mutex in lock hierarchy.
477 * First, trylock i_mutex. If fails, unlock
478 * sysfs_mutex and lock them in order.
480 if (!mutex_trylock(&inode->i_mutex)) {
481 mutex_unlock(&sysfs_mutex);
482 mutex_lock(&inode->i_mutex);
483 mutex_lock(&sysfs_mutex);
490 * sysfs_add_one - add sysfs_dirent to parent
491 * @acxt: addrm context to use
492 * @sd: sysfs_dirent to be added
494 * Get @acxt->parent_sd and set sd->s_parent to it and increment
495 * nlink of parent inode if @sd is a directory. @sd is NOT
496 * linked into the children list of the parent. The caller
497 * should invoke sysfs_link_sibling() after this function
498 * completes if @sd needs to be on the children list.
500 * This function should be called between calls to
501 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
502 * passed the same @acxt as passed to sysfs_addrm_start().
505 * Determined by sysfs_addrm_start().
508 * 0 on success, -EEXIST if entry with the given name already
511 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
513 if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
516 sd->s_parent = sysfs_get(acxt->parent_sd);
518 if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
519 inc_nlink(acxt->parent_inode);
523 sysfs_link_sibling(sd);
529 * sysfs_remove_one - remove sysfs_dirent from parent
530 * @acxt: addrm context to use
531 * @sd: sysfs_dirent to be added
533 * Mark @sd removed and drop nlink of parent inode if @sd is a
534 * directory. @sd is NOT unlinked from the children list of the
535 * parent. The caller is repsonsible for removing @sd from the
536 * children list before calling this function.
538 * This function should be called between calls to
539 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
540 * passed the same @acxt as passed to sysfs_addrm_start().
543 * Determined by sysfs_addrm_start().
545 void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
547 BUG_ON(sd->s_flags & SYSFS_FLAG_REMOVED);
549 sysfs_unlink_sibling(sd);
551 sd->s_flags |= SYSFS_FLAG_REMOVED;
552 sd->s_sibling = acxt->removed;
555 if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
556 drop_nlink(acxt->parent_inode);
562 * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
563 * @sd: target sysfs_dirent
565 * Drop dentry for @sd. @sd must have been unlinked from its
566 * parent on entry to this function such that it can't be looked
569 static void sysfs_drop_dentry(struct sysfs_dirent *sd)
572 struct dentry *dentry;
574 inode = ilookup(sysfs_sb, sd->s_ino);
578 /* Drop any existing dentries associated with sd.
580 * For the dentry to be properly freed we need to grab a
581 * reference to the dentry under the dcache lock, unhash it,
582 * and then put it. The playing with the dentry count allows
583 * dput to immediately free the dentry if it is not in use.
586 spin_lock(&dcache_lock);
587 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
588 if (d_unhashed(dentry))
591 spin_lock(&dentry->d_lock);
593 spin_unlock(&dentry->d_lock);
594 spin_unlock(&dcache_lock);
598 spin_unlock(&dcache_lock);
600 /* adjust nlink and update timestamp */
601 mutex_lock(&inode->i_mutex);
603 inode->i_ctime = CURRENT_TIME;
605 if (sysfs_type(sd) == SYSFS_DIR)
608 mutex_unlock(&inode->i_mutex);
614 * sysfs_addrm_finish - finish up sysfs_dirent add/remove
615 * @acxt: addrm context to finish up
617 * Finish up sysfs_dirent add/remove. Resources acquired by
618 * sysfs_addrm_start() are released and removed sysfs_dirents are
619 * cleaned up. Timestamps on the parent inode are updated.
622 * All mutexes acquired by sysfs_addrm_start() are released.
624 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
626 /* release resources acquired by sysfs_addrm_start() */
627 mutex_unlock(&sysfs_mutex);
628 if (acxt->parent_inode) {
629 struct inode *inode = acxt->parent_inode;
631 /* if added/removed, update timestamps on the parent */
633 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
635 mutex_unlock(&inode->i_mutex);
639 /* kill removed sysfs_dirents */
640 while (acxt->removed) {
641 struct sysfs_dirent *sd = acxt->removed;
643 acxt->removed = sd->s_sibling;
644 sd->s_sibling = NULL;
646 sysfs_drop_dentry(sd);
647 sysfs_deactivate(sd);
653 * sysfs_find_dirent - find sysfs_dirent with the given name
654 * @parent_sd: sysfs_dirent to search under
655 * @name: name to look for
657 * Look for sysfs_dirent with name @name under @parent_sd.
660 * mutex_lock(sysfs_mutex)
663 * Pointer to sysfs_dirent if found, NULL if not.
665 struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
666 const unsigned char *name)
668 struct sysfs_dirent *sd;
670 for (sd = parent_sd->s_children; sd; sd = sd->s_sibling)
671 if (!strcmp(sd->s_name, name))
677 * sysfs_get_dirent - find and get sysfs_dirent with the given name
678 * @parent_sd: sysfs_dirent to search under
679 * @name: name to look for
681 * Look for sysfs_dirent with name @name under @parent_sd and get
685 * Kernel thread context (may sleep). Grabs sysfs_mutex.
688 * Pointer to sysfs_dirent if found, NULL if not.
690 struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
691 const unsigned char *name)
693 struct sysfs_dirent *sd;
695 mutex_lock(&sysfs_mutex);
696 sd = sysfs_find_dirent(parent_sd, name);
698 mutex_unlock(&sysfs_mutex);
703 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
704 const char *name, struct sysfs_dirent **p_sd)
706 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
707 struct sysfs_addrm_cxt acxt;
708 struct sysfs_dirent *sd;
712 sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
715 sd->s_elem.dir.kobj = kobj;
718 sysfs_addrm_start(&acxt, parent_sd);
719 rc = sysfs_add_one(&acxt, sd);
720 sysfs_addrm_finish(&acxt);
730 int sysfs_create_subdir(struct kobject *kobj, const char *name,
731 struct sysfs_dirent **p_sd)
733 return create_dir(kobj, kobj->sd, name, p_sd);
737 * sysfs_create_dir - create a directory for an object.
738 * @kobj: object we're creating directory for.
740 int sysfs_create_dir(struct kobject * kobj)
742 struct sysfs_dirent *parent_sd, *sd;
748 parent_sd = kobj->parent->sd;
750 parent_sd = &sysfs_root;
752 error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
758 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
759 struct nameidata *nd)
761 struct dentry *ret = NULL;
762 struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
763 struct sysfs_dirent *sd;
766 mutex_lock(&sysfs_mutex);
768 sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);
774 /* attach dentry and inode */
775 inode = sysfs_get_inode(sd);
777 ret = ERR_PTR(-ENOMEM);
781 d_instantiate(dentry, inode);
782 sysfs_attach_dentry(sd, dentry);
785 mutex_unlock(&sysfs_mutex);
789 const struct inode_operations sysfs_dir_inode_operations = {
790 .lookup = sysfs_lookup,
791 .setattr = sysfs_setattr,
794 static void remove_dir(struct sysfs_dirent *sd)
796 struct sysfs_addrm_cxt acxt;
798 sysfs_addrm_start(&acxt, sd->s_parent);
799 sysfs_remove_one(&acxt, sd);
800 sysfs_addrm_finish(&acxt);
803 void sysfs_remove_subdir(struct sysfs_dirent *sd)
809 static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
811 struct sysfs_addrm_cxt acxt;
812 struct sysfs_dirent **pos;
817 pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
818 sysfs_addrm_start(&acxt, dir_sd);
819 pos = &dir_sd->s_children;
821 struct sysfs_dirent *sd = *pos;
823 if (sysfs_type(sd) != SYSFS_DIR)
824 sysfs_remove_one(&acxt, sd);
826 pos = &(*pos)->s_sibling;
828 sysfs_addrm_finish(&acxt);
834 * sysfs_remove_dir - remove an object's directory.
837 * The only thing special about this is that we remove any files in
838 * the directory before we remove the directory, and we've inlined
839 * what used to be sysfs_rmdir() below, instead of calling separately.
842 void sysfs_remove_dir(struct kobject * kobj)
844 struct sysfs_dirent *sd = kobj->sd;
846 spin_lock(&sysfs_assoc_lock);
848 spin_unlock(&sysfs_assoc_lock);
850 __sysfs_remove_dir(sd);
853 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
855 struct sysfs_dirent *sd;
856 struct dentry *parent = NULL;
857 struct dentry *old_dentry = NULL, *new_dentry = NULL;
858 const char *dup_name = NULL;
861 /* get the original dentry */
863 old_dentry = sysfs_get_dentry(sd);
864 if (IS_ERR(old_dentry)) {
865 error = PTR_ERR(old_dentry);
869 parent = old_dentry->d_parent;
871 /* lock parent and get dentry for new name */
872 mutex_lock(&parent->d_inode->i_mutex);
874 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
875 if (IS_ERR(new_dentry)) {
876 error = PTR_ERR(new_dentry);
881 if (old_dentry == new_dentry)
885 if (new_dentry->d_inode)
888 /* rename kobject and sysfs_dirent */
890 new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
894 error = kobject_set_name(kobj, "%s", new_name);
898 mutex_lock(&sysfs_mutex);
899 dup_name = sd->s_name;
900 sd->s_name = new_name;
901 mutex_unlock(&sysfs_mutex);
904 d_add(new_dentry, NULL);
905 d_move(sd->s_dentry, new_dentry);
913 mutex_unlock(&parent->d_inode->i_mutex);
921 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
923 struct sysfs_dirent *sd = kobj->sd;
924 struct sysfs_dirent *new_parent_sd;
925 struct dentry *old_parent, *new_parent = NULL;
926 struct dentry *old_dentry = NULL, *new_dentry = NULL;
929 BUG_ON(!sd->s_parent);
930 new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
933 old_dentry = sysfs_get_dentry(sd);
934 if (IS_ERR(old_dentry)) {
935 error = PTR_ERR(old_dentry);
938 old_parent = sd->s_parent->s_dentry;
940 new_parent = sysfs_get_dentry(new_parent_sd);
941 if (IS_ERR(new_parent)) {
942 error = PTR_ERR(new_parent);
946 if (old_parent->d_inode == new_parent->d_inode) {
948 goto out_dput; /* nothing to move */
951 mutex_lock(&old_parent->d_inode->i_mutex);
952 if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
953 mutex_unlock(&old_parent->d_inode->i_mutex);
957 new_dentry = lookup_one_len(kobject_name(kobj), new_parent, strlen(kobject_name(kobj)));
958 if (IS_ERR(new_dentry)) {
959 error = PTR_ERR(new_dentry);
963 d_add(new_dentry, NULL);
964 d_move(sd->s_dentry, new_dentry);
967 /* Remove from old parent's list and insert into new parent's list. */
968 mutex_lock(&sysfs_mutex);
970 sysfs_unlink_sibling(sd);
971 sysfs_get(new_parent_sd);
972 sysfs_put(sd->s_parent);
973 sd->s_parent = new_parent_sd;
974 sysfs_link_sibling(sd);
976 mutex_unlock(&sysfs_mutex);
979 mutex_unlock(&new_parent->d_inode->i_mutex);
980 mutex_unlock(&old_parent->d_inode->i_mutex);
988 /* Relationship between s_mode and the DT_xxx types */
989 static inline unsigned char dt_type(struct sysfs_dirent *sd)
991 return (sd->s_mode >> 12) & 15;
994 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
996 struct dentry *dentry = filp->f_path.dentry;
997 struct sysfs_dirent * parent_sd = dentry->d_fsdata;
998 struct sysfs_dirent *pos;
1001 if (filp->f_pos == 0) {
1002 ino = parent_sd->s_ino;
1003 if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
1006 if (filp->f_pos == 1) {
1007 if (parent_sd->s_parent)
1008 ino = parent_sd->s_parent->s_ino;
1010 ino = parent_sd->s_ino;
1011 if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
1014 if ((filp->f_pos > 1) && (filp->f_pos < INT_MAX)) {
1015 mutex_lock(&sysfs_mutex);
1017 /* Skip the dentries we have already reported */
1018 pos = parent_sd->s_children;
1019 while (pos && (filp->f_pos > pos->s_ino))
1020 pos = pos->s_sibling;
1022 for ( ; pos; pos = pos->s_sibling) {
1028 filp->f_pos = ino = pos->s_ino;
1030 if (filldir(dirent, name, len, filp->f_pos, ino,
1035 filp->f_pos = INT_MAX;
1036 mutex_unlock(&sysfs_mutex);
1042 const struct file_operations sysfs_dir_operations = {
1043 .read = generic_read_dir,
1044 .readdir = sysfs_readdir,