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 DEFINE_MUTEX(sysfs_rename_mutex);
19 spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
21 static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
22 static DEFINE_IDA(sysfs_ino_ida);
25 * sysfs_link_sibling - link sysfs_dirent into sibling list
26 * @sd: sysfs_dirent of interest
28 * Link @sd into its sibling list which starts from
29 * sd->s_parent->s_children.
32 * mutex_lock(sysfs_mutex)
34 static void sysfs_link_sibling(struct sysfs_dirent *sd)
36 struct sysfs_dirent *parent_sd = sd->s_parent;
37 struct sysfs_dirent **pos;
39 BUG_ON(sd->s_sibling);
41 /* Store directory entries in order by ino. This allows
42 * readdir to properly restart without having to add a
43 * cursor into the s_children list.
45 for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
46 if (sd->s_ino < (*pos)->s_ino)
54 * sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
55 * @sd: sysfs_dirent of interest
57 * Unlink @sd from its sibling list which starts from
58 * sd->s_parent->s_children.
61 * mutex_lock(sysfs_mutex)
63 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
65 struct sysfs_dirent **pos;
67 for (pos = &sd->s_parent->s_children; *pos; pos = &(*pos)->s_sibling) {
77 * sysfs_get_dentry - get dentry for the given sysfs_dirent
78 * @sd: sysfs_dirent of interest
80 * Get dentry for @sd. Dentry is looked up if currently not
81 * present. This function climbs sysfs_dirent tree till it
82 * reaches a sysfs_dirent with valid dentry attached and descends
83 * down from there looking up dentry for each step.
86 * mutex_lock(sysfs_rename_mutex)
89 * Pointer to found dentry on success, ERR_PTR() value on error.
91 struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
93 struct sysfs_dirent *cur;
94 struct dentry *parent_dentry, *dentry;
97 /* Find the first parent which has valid s_dentry and get the
100 mutex_lock(&sysfs_mutex);
102 spin_lock(&sysfs_assoc_lock);
104 spin_lock(&dcache_lock);
109 while (!cur->s_dentry || !cur->s_dentry->d_inode) {
110 if (cur->s_flags & SYSFS_FLAG_REMOVED) {
111 dentry = ERR_PTR(-ENOENT);
119 dentry = dget_locked(cur->s_dentry);
121 spin_unlock(&dcache_lock);
122 spin_unlock(&sysfs_assoc_lock);
124 /* from the found dentry, look up depth times */
126 /* find and get depth'th ancestor */
127 for (cur = sd, i = 0; cur && i < depth; i++)
130 /* This can happen if tree structure was modified due
131 * to move/rename. Restart.
140 mutex_unlock(&sysfs_mutex);
143 parent_dentry = dentry;
144 mutex_lock(&parent_dentry->d_inode->i_mutex);
145 dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
146 strlen(cur->s_name));
147 mutex_unlock(&parent_dentry->d_inode->i_mutex);
150 if (IS_ERR(dentry)) {
155 mutex_lock(&sysfs_mutex);
156 spin_lock(&sysfs_assoc_lock);
158 /* This, again, can happen if tree structure has
159 * changed and we looked up the wrong thing. Restart.
161 if (cur->s_dentry != dentry) {
167 spin_unlock(&sysfs_assoc_lock);
172 mutex_unlock(&sysfs_mutex);
177 * sysfs_get_active - get an active reference to sysfs_dirent
178 * @sd: sysfs_dirent to get an active reference to
180 * Get an active reference of @sd. This function is noop if @sd
184 * Pointer to @sd on success, NULL on failure.
186 struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
194 v = atomic_read(&sd->s_active);
198 t = atomic_cmpxchg(&sd->s_active, v, v + 1);
209 * sysfs_put_active - put an active reference to sysfs_dirent
210 * @sd: sysfs_dirent to put an active reference to
212 * Put an active reference to @sd. This function is noop if @sd
215 void sysfs_put_active(struct sysfs_dirent *sd)
217 struct completion *cmpl;
223 v = atomic_dec_return(&sd->s_active);
224 if (likely(v != SD_DEACTIVATED_BIAS))
227 /* atomic_dec_return() is a mb(), we'll always see the updated
230 cmpl = (void *)sd->s_sibling;
235 * sysfs_get_active_two - get active references to sysfs_dirent and parent
236 * @sd: sysfs_dirent of interest
238 * Get active reference to @sd and its parent. Parent's active
239 * reference is grabbed first. This function is noop if @sd is
243 * Pointer to @sd on success, NULL on failure.
245 struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
248 if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
250 if (unlikely(!sysfs_get_active(sd))) {
251 sysfs_put_active(sd->s_parent);
259 * sysfs_put_active_two - put active references to sysfs_dirent and parent
260 * @sd: sysfs_dirent of interest
262 * Put active references to @sd and its parent. This function is
263 * noop if @sd is NULL.
265 void sysfs_put_active_two(struct sysfs_dirent *sd)
268 sysfs_put_active(sd);
269 sysfs_put_active(sd->s_parent);
274 * sysfs_deactivate - deactivate sysfs_dirent
275 * @sd: sysfs_dirent to deactivate
277 * Deny new active references and drain existing ones.
279 static void sysfs_deactivate(struct sysfs_dirent *sd)
281 DECLARE_COMPLETION_ONSTACK(wait);
284 BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
285 sd->s_sibling = (void *)&wait;
287 /* atomic_add_return() is a mb(), put_active() will always see
288 * the updated sd->s_sibling.
290 v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
292 if (v != SD_DEACTIVATED_BIAS)
293 wait_for_completion(&wait);
295 sd->s_sibling = NULL;
298 static int sysfs_alloc_ino(ino_t *pino)
303 spin_lock(&sysfs_ino_lock);
304 rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
305 spin_unlock(&sysfs_ino_lock);
308 if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
317 static void sysfs_free_ino(ino_t ino)
319 spin_lock(&sysfs_ino_lock);
320 ida_remove(&sysfs_ino_ida, ino);
321 spin_unlock(&sysfs_ino_lock);
324 void release_sysfs_dirent(struct sysfs_dirent * sd)
326 struct sysfs_dirent *parent_sd;
329 /* Moving/renaming is always done while holding reference.
330 * sd->s_parent won't change beneath us.
332 parent_sd = sd->s_parent;
334 if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
335 sysfs_put(sd->s_elem.symlink.target_sd);
336 if (sysfs_type(sd) & SYSFS_COPY_NAME)
339 sysfs_free_ino(sd->s_ino);
340 kmem_cache_free(sysfs_dir_cachep, sd);
343 if (sd && atomic_dec_and_test(&sd->s_count))
347 static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
349 struct sysfs_dirent * sd = dentry->d_fsdata;
352 /* sd->s_dentry is protected with sysfs_assoc_lock.
353 * This allows sysfs_drop_dentry() to dereference it.
355 spin_lock(&sysfs_assoc_lock);
357 /* The dentry might have been deleted or another
358 * lookup could have happened updating sd->s_dentry to
359 * point the new dentry. Ignore if it isn't pointing
362 if (sd->s_dentry == dentry)
364 spin_unlock(&sysfs_assoc_lock);
370 static struct dentry_operations sysfs_dentry_ops = {
371 .d_iput = sysfs_d_iput,
374 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
376 char *dup_name = NULL;
377 struct sysfs_dirent *sd;
379 if (type & SYSFS_COPY_NAME) {
380 name = dup_name = kstrdup(name, GFP_KERNEL);
385 sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
389 if (sysfs_alloc_ino(&sd->s_ino))
392 atomic_set(&sd->s_count, 1);
393 atomic_set(&sd->s_active, 0);
394 atomic_set(&sd->s_event, 1);
403 kmem_cache_free(sysfs_dir_cachep, sd);
410 * sysfs_attach_dentry - associate sysfs_dirent with dentry
411 * @sd: target sysfs_dirent
412 * @dentry: dentry to associate
414 * Associate @sd with @dentry. This is protected by
415 * sysfs_assoc_lock to avoid race with sysfs_d_iput().
418 * mutex_lock(sysfs_mutex)
420 static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
422 dentry->d_op = &sysfs_dentry_ops;
423 dentry->d_fsdata = sysfs_get(sd);
425 /* protect sd->s_dentry against sysfs_d_iput */
426 spin_lock(&sysfs_assoc_lock);
427 sd->s_dentry = dentry;
428 spin_unlock(&sysfs_assoc_lock);
433 static int sysfs_ilookup_test(struct inode *inode, void *arg)
435 struct sysfs_dirent *sd = arg;
436 return inode->i_ino == sd->s_ino;
440 * sysfs_addrm_start - prepare for sysfs_dirent add/remove
441 * @acxt: pointer to sysfs_addrm_cxt to be used
442 * @parent_sd: parent sysfs_dirent
444 * This function is called when the caller is about to add or
445 * remove sysfs_dirent under @parent_sd. This function acquires
446 * sysfs_mutex, grabs inode for @parent_sd if available and lock
447 * i_mutex of it. @acxt is used to keep and pass context to
448 * other addrm functions.
451 * Kernel thread context (may sleep). sysfs_mutex is locked on
452 * return. i_mutex of parent inode is locked on return if
455 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
456 struct sysfs_dirent *parent_sd)
460 memset(acxt, 0, sizeof(*acxt));
461 acxt->parent_sd = parent_sd;
463 /* Lookup parent inode. inode initialization and I_NEW
464 * clearing are protected by sysfs_mutex. By grabbing it and
465 * looking up with _nowait variant, inode state can be
466 * determined reliably.
468 mutex_lock(&sysfs_mutex);
470 inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
473 if (inode && !(inode->i_state & I_NEW)) {
474 /* parent inode available */
475 acxt->parent_inode = inode;
477 /* sysfs_mutex is below i_mutex in lock hierarchy.
478 * First, trylock i_mutex. If fails, unlock
479 * sysfs_mutex and lock them in order.
481 if (!mutex_trylock(&inode->i_mutex)) {
482 mutex_unlock(&sysfs_mutex);
483 mutex_lock(&inode->i_mutex);
484 mutex_lock(&sysfs_mutex);
491 * sysfs_add_one - add sysfs_dirent to parent
492 * @acxt: addrm context to use
493 * @sd: sysfs_dirent to be added
495 * Get @acxt->parent_sd and set sd->s_parent to it and increment
496 * nlink of parent inode if @sd is a directory. @sd is NOT
497 * linked into the children list of the parent. The caller
498 * should invoke sysfs_link_sibling() after this function
499 * completes if @sd needs to be on the children list.
501 * This function should be called between calls to
502 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
503 * passed the same @acxt as passed to sysfs_addrm_start().
506 * Determined by sysfs_addrm_start().
509 * 0 on success, -EEXIST if entry with the given name already
512 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
514 if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
517 sd->s_parent = sysfs_get(acxt->parent_sd);
519 if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
520 inc_nlink(acxt->parent_inode);
524 sysfs_link_sibling(sd);
530 * sysfs_remove_one - remove sysfs_dirent from parent
531 * @acxt: addrm context to use
532 * @sd: sysfs_dirent to be added
534 * Mark @sd removed and drop nlink of parent inode if @sd is a
535 * directory. @sd is NOT unlinked from the children list of the
536 * parent. The caller is repsonsible for removing @sd from the
537 * children list before calling this function.
539 * This function should be called between calls to
540 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
541 * passed the same @acxt as passed to sysfs_addrm_start().
544 * Determined by sysfs_addrm_start().
546 void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
548 BUG_ON(sd->s_flags & SYSFS_FLAG_REMOVED);
550 sysfs_unlink_sibling(sd);
552 sd->s_flags |= SYSFS_FLAG_REMOVED;
553 sd->s_sibling = acxt->removed;
556 if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
557 drop_nlink(acxt->parent_inode);
563 * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
564 * @sd: target sysfs_dirent
566 * Drop dentry for @sd. @sd must have been unlinked from its
567 * parent on entry to this function such that it can't be looked
570 static void sysfs_drop_dentry(struct sysfs_dirent *sd)
573 struct dentry *dentry;
575 inode = ilookup(sysfs_sb, sd->s_ino);
579 /* Drop any existing dentries associated with sd.
581 * For the dentry to be properly freed we need to grab a
582 * reference to the dentry under the dcache lock, unhash it,
583 * and then put it. The playing with the dentry count allows
584 * dput to immediately free the dentry if it is not in use.
587 spin_lock(&dcache_lock);
588 list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
589 if (d_unhashed(dentry))
592 spin_lock(&dentry->d_lock);
594 spin_unlock(&dentry->d_lock);
595 spin_unlock(&dcache_lock);
599 spin_unlock(&dcache_lock);
601 /* adjust nlink and update timestamp */
602 mutex_lock(&inode->i_mutex);
604 inode->i_ctime = CURRENT_TIME;
606 if (sysfs_type(sd) == SYSFS_DIR)
609 mutex_unlock(&inode->i_mutex);
615 * sysfs_addrm_finish - finish up sysfs_dirent add/remove
616 * @acxt: addrm context to finish up
618 * Finish up sysfs_dirent add/remove. Resources acquired by
619 * sysfs_addrm_start() are released and removed sysfs_dirents are
620 * cleaned up. Timestamps on the parent inode are updated.
623 * All mutexes acquired by sysfs_addrm_start() are released.
625 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
627 /* release resources acquired by sysfs_addrm_start() */
628 mutex_unlock(&sysfs_mutex);
629 if (acxt->parent_inode) {
630 struct inode *inode = acxt->parent_inode;
632 /* if added/removed, update timestamps on the parent */
634 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
636 mutex_unlock(&inode->i_mutex);
640 /* kill removed sysfs_dirents */
641 while (acxt->removed) {
642 struct sysfs_dirent *sd = acxt->removed;
644 acxt->removed = sd->s_sibling;
645 sd->s_sibling = NULL;
647 sysfs_drop_dentry(sd);
648 sysfs_deactivate(sd);
654 * sysfs_find_dirent - find sysfs_dirent with the given name
655 * @parent_sd: sysfs_dirent to search under
656 * @name: name to look for
658 * Look for sysfs_dirent with name @name under @parent_sd.
661 * mutex_lock(sysfs_mutex)
664 * Pointer to sysfs_dirent if found, NULL if not.
666 struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
667 const unsigned char *name)
669 struct sysfs_dirent *sd;
671 for (sd = parent_sd->s_children; sd; sd = sd->s_sibling)
672 if (!strcmp(sd->s_name, name))
678 * sysfs_get_dirent - find and get sysfs_dirent with the given name
679 * @parent_sd: sysfs_dirent to search under
680 * @name: name to look for
682 * Look for sysfs_dirent with name @name under @parent_sd and get
686 * Kernel thread context (may sleep). Grabs sysfs_mutex.
689 * Pointer to sysfs_dirent if found, NULL if not.
691 struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
692 const unsigned char *name)
694 struct sysfs_dirent *sd;
696 mutex_lock(&sysfs_mutex);
697 sd = sysfs_find_dirent(parent_sd, name);
699 mutex_unlock(&sysfs_mutex);
704 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
705 const char *name, struct sysfs_dirent **p_sd)
707 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
708 struct sysfs_addrm_cxt acxt;
709 struct sysfs_dirent *sd;
713 sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
716 sd->s_elem.dir.kobj = kobj;
719 sysfs_addrm_start(&acxt, parent_sd);
720 rc = sysfs_add_one(&acxt, sd);
721 sysfs_addrm_finish(&acxt);
731 int sysfs_create_subdir(struct kobject *kobj, const char *name,
732 struct sysfs_dirent **p_sd)
734 return create_dir(kobj, kobj->sd, name, p_sd);
738 * sysfs_create_dir - create a directory for an object.
739 * @kobj: object we're creating directory for.
741 int sysfs_create_dir(struct kobject * kobj)
743 struct sysfs_dirent *parent_sd, *sd;
749 parent_sd = kobj->parent->sd;
751 parent_sd = &sysfs_root;
753 error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
759 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
760 struct nameidata *nd)
762 struct dentry *ret = NULL;
763 struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
764 struct sysfs_dirent *sd;
767 mutex_lock(&sysfs_mutex);
769 sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);
775 /* attach dentry and inode */
776 inode = sysfs_get_inode(sd);
778 ret = ERR_PTR(-ENOMEM);
782 d_instantiate(dentry, inode);
783 sysfs_attach_dentry(sd, dentry);
786 mutex_unlock(&sysfs_mutex);
790 const struct inode_operations sysfs_dir_inode_operations = {
791 .lookup = sysfs_lookup,
792 .setattr = sysfs_setattr,
795 static void remove_dir(struct sysfs_dirent *sd)
797 struct sysfs_addrm_cxt acxt;
799 sysfs_addrm_start(&acxt, sd->s_parent);
800 sysfs_remove_one(&acxt, sd);
801 sysfs_addrm_finish(&acxt);
804 void sysfs_remove_subdir(struct sysfs_dirent *sd)
810 static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
812 struct sysfs_addrm_cxt acxt;
813 struct sysfs_dirent **pos;
818 pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
819 sysfs_addrm_start(&acxt, dir_sd);
820 pos = &dir_sd->s_children;
822 struct sysfs_dirent *sd = *pos;
824 if (sysfs_type(sd) != SYSFS_DIR)
825 sysfs_remove_one(&acxt, sd);
827 pos = &(*pos)->s_sibling;
829 sysfs_addrm_finish(&acxt);
835 * sysfs_remove_dir - remove an object's directory.
838 * The only thing special about this is that we remove any files in
839 * the directory before we remove the directory, and we've inlined
840 * what used to be sysfs_rmdir() below, instead of calling separately.
843 void sysfs_remove_dir(struct kobject * kobj)
845 struct sysfs_dirent *sd = kobj->sd;
847 spin_lock(&sysfs_assoc_lock);
849 spin_unlock(&sysfs_assoc_lock);
851 __sysfs_remove_dir(sd);
854 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
856 struct sysfs_dirent *sd;
857 struct dentry *parent = NULL;
858 struct dentry *old_dentry = NULL, *new_dentry = NULL;
859 const char *dup_name = NULL;
862 mutex_lock(&sysfs_rename_mutex);
864 /* get the original dentry */
866 old_dentry = sysfs_get_dentry(sd);
867 if (IS_ERR(old_dentry)) {
868 error = PTR_ERR(old_dentry);
872 parent = old_dentry->d_parent;
874 /* lock parent and get dentry for new name */
875 mutex_lock(&parent->d_inode->i_mutex);
877 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
878 if (IS_ERR(new_dentry)) {
879 error = PTR_ERR(new_dentry);
884 if (old_dentry == new_dentry)
888 if (new_dentry->d_inode)
891 /* rename kobject and sysfs_dirent */
893 new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
897 error = kobject_set_name(kobj, "%s", new_name);
901 mutex_lock(&sysfs_mutex);
902 dup_name = sd->s_name;
903 sd->s_name = new_name;
904 mutex_unlock(&sysfs_mutex);
907 d_add(new_dentry, NULL);
908 d_move(sd->s_dentry, new_dentry);
916 mutex_unlock(&parent->d_inode->i_mutex);
921 mutex_unlock(&sysfs_rename_mutex);
925 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
927 struct sysfs_dirent *sd = kobj->sd;
928 struct sysfs_dirent *new_parent_sd;
929 struct dentry *old_parent, *new_parent = NULL;
930 struct dentry *old_dentry = NULL, *new_dentry = NULL;
933 mutex_lock(&sysfs_rename_mutex);
934 BUG_ON(!sd->s_parent);
935 new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
938 old_dentry = sysfs_get_dentry(sd);
939 if (IS_ERR(old_dentry)) {
940 error = PTR_ERR(old_dentry);
943 old_parent = sd->s_parent->s_dentry;
945 new_parent = sysfs_get_dentry(new_parent_sd);
946 if (IS_ERR(new_parent)) {
947 error = PTR_ERR(new_parent);
951 if (old_parent->d_inode == new_parent->d_inode) {
953 goto out_dput; /* nothing to move */
956 mutex_lock(&old_parent->d_inode->i_mutex);
957 if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
958 mutex_unlock(&old_parent->d_inode->i_mutex);
962 new_dentry = lookup_one_len(kobject_name(kobj), new_parent, strlen(kobject_name(kobj)));
963 if (IS_ERR(new_dentry)) {
964 error = PTR_ERR(new_dentry);
968 d_add(new_dentry, NULL);
969 d_move(sd->s_dentry, new_dentry);
972 /* Remove from old parent's list and insert into new parent's list. */
973 mutex_lock(&sysfs_mutex);
975 sysfs_unlink_sibling(sd);
976 sysfs_get(new_parent_sd);
977 sysfs_put(sd->s_parent);
978 sd->s_parent = new_parent_sd;
979 sysfs_link_sibling(sd);
981 mutex_unlock(&sysfs_mutex);
984 mutex_unlock(&new_parent->d_inode->i_mutex);
985 mutex_unlock(&old_parent->d_inode->i_mutex);
990 mutex_unlock(&sysfs_rename_mutex);
994 /* Relationship between s_mode and the DT_xxx types */
995 static inline unsigned char dt_type(struct sysfs_dirent *sd)
997 return (sd->s_mode >> 12) & 15;
1000 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1002 struct dentry *dentry = filp->f_path.dentry;
1003 struct sysfs_dirent * parent_sd = dentry->d_fsdata;
1004 struct sysfs_dirent *pos;
1007 if (filp->f_pos == 0) {
1008 ino = parent_sd->s_ino;
1009 if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
1012 if (filp->f_pos == 1) {
1013 if (parent_sd->s_parent)
1014 ino = parent_sd->s_parent->s_ino;
1016 ino = parent_sd->s_ino;
1017 if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
1020 if ((filp->f_pos > 1) && (filp->f_pos < INT_MAX)) {
1021 mutex_lock(&sysfs_mutex);
1023 /* Skip the dentries we have already reported */
1024 pos = parent_sd->s_children;
1025 while (pos && (filp->f_pos > pos->s_ino))
1026 pos = pos->s_sibling;
1028 for ( ; pos; pos = pos->s_sibling) {
1034 filp->f_pos = ino = pos->s_ino;
1036 if (filldir(dirent, name, len, filp->f_pos, ino,
1041 filp->f_pos = INT_MAX;
1042 mutex_unlock(&sysfs_mutex);
1048 const struct file_operations sysfs_dir_operations = {
1049 .read = generic_read_dir,
1050 .readdir = sysfs_readdir,