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>
25 #include <linux/hash.h>
28 DEFINE_MUTEX(sysfs_mutex);
29 DEFINE_SPINLOCK(sysfs_symlink_target_lock);
31 #define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
33 static DEFINE_SPINLOCK(sysfs_ino_lock);
34 static DEFINE_IDA(sysfs_ino_ida);
38 * @name: Null terminated string to hash
39 * @ns: Namespace tag to hash
41 * Returns 31 bit hash of ns + name (so it fits in an off_t )
43 static unsigned int sysfs_name_hash(const char *name, const void *ns)
45 unsigned long hash = init_name_hash();
46 unsigned int len = strlen(name);
48 hash = partial_name_hash(*name++, hash);
49 hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
51 /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
59 static int sysfs_name_compare(unsigned int hash, const char *name,
60 const void *ns, const struct sysfs_dirent *sd)
62 if (hash != sd->s_hash)
63 return hash - sd->s_hash;
66 return strcmp(name, sd->s_name);
69 static int sysfs_sd_compare(const struct sysfs_dirent *left,
70 const struct sysfs_dirent *right)
72 return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns,
77 * sysfs_link_sibling - link sysfs_dirent into sibling rbtree
78 * @sd: sysfs_dirent of interest
80 * Link @sd into its sibling rbtree which starts from
81 * sd->s_parent->s_dir.children.
84 * mutex_lock(sysfs_mutex)
87 * 0 on susccess -EEXIST on failure.
89 static int sysfs_link_sibling(struct sysfs_dirent *sd)
91 struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
92 struct rb_node *parent = NULL;
94 if (sysfs_type(sd) == SYSFS_DIR)
95 sd->s_parent->s_dir.subdirs++;
98 struct sysfs_dirent *pos;
101 pos = to_sysfs_dirent(*node);
103 result = sysfs_sd_compare(sd, pos);
105 node = &pos->s_rb.rb_left;
107 node = &pos->s_rb.rb_right;
111 /* add new node and rebalance the tree */
112 rb_link_node(&sd->s_rb, parent, node);
113 rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
118 * sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
119 * @sd: sysfs_dirent of interest
121 * Unlink @sd from its sibling rbtree which starts from
122 * sd->s_parent->s_dir.children.
125 * mutex_lock(sysfs_mutex)
127 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
129 if (sysfs_type(sd) == SYSFS_DIR)
130 sd->s_parent->s_dir.subdirs--;
132 rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
136 * sysfs_get_active - get an active reference to sysfs_dirent
137 * @sd: sysfs_dirent to get an active reference to
139 * Get an active reference of @sd. This function is noop if @sd
143 * Pointer to @sd on success, NULL on failure.
145 struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
150 if (!atomic_inc_unless_negative(&sd->s_active))
153 if (likely(!sysfs_ignore_lockdep(sd)))
154 rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
159 * sysfs_put_active - put an active reference to sysfs_dirent
160 * @sd: sysfs_dirent to put an active reference to
162 * Put an active reference to @sd. This function is noop if @sd
165 void sysfs_put_active(struct sysfs_dirent *sd)
172 if (likely(!sysfs_ignore_lockdep(sd)))
173 rwsem_release(&sd->dep_map, 1, _RET_IP_);
174 v = atomic_dec_return(&sd->s_active);
175 if (likely(v != SD_DEACTIVATED_BIAS))
178 /* atomic_dec_return() is a mb(), we'll always see the updated
181 complete(sd->u.completion);
185 * sysfs_deactivate - deactivate sysfs_dirent
186 * @sd: sysfs_dirent to deactivate
188 * Deny new active references and drain existing ones.
190 static void sysfs_deactivate(struct sysfs_dirent *sd)
192 DECLARE_COMPLETION_ONSTACK(wait);
195 BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
197 if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
200 sd->u.completion = (void *)&wait;
202 rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
203 /* atomic_add_return() is a mb(), put_active() will always see
204 * the updated sd->u.completion.
206 v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
208 if (v != SD_DEACTIVATED_BIAS) {
209 lock_contended(&sd->dep_map, _RET_IP_);
210 wait_for_completion(&wait);
213 lock_acquired(&sd->dep_map, _RET_IP_);
214 rwsem_release(&sd->dep_map, 1, _RET_IP_);
217 static int sysfs_alloc_ino(unsigned int *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(unsigned int 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 WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED),
254 "sysfs: free using entry: %s/%s\n",
255 parent_sd ? parent_sd->s_name : "", sd->s_name);
257 if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
258 sysfs_put(sd->s_symlink.target_sd);
259 if (sysfs_type(sd) & SYSFS_COPY_NAME)
261 if (sd->s_iattr && sd->s_iattr->ia_secdata)
262 security_release_secctx(sd->s_iattr->ia_secdata,
263 sd->s_iattr->ia_secdata_len);
265 sysfs_free_ino(sd->s_ino);
266 kmem_cache_free(sysfs_dir_cachep, sd);
269 if (sd && atomic_dec_and_test(&sd->s_count))
273 static int sysfs_dentry_delete(const struct dentry *dentry)
275 struct sysfs_dirent *sd = dentry->d_fsdata;
276 return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED));
279 static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
281 struct sysfs_dirent *sd;
283 if (flags & LOOKUP_RCU)
286 sd = dentry->d_fsdata;
287 mutex_lock(&sysfs_mutex);
289 /* The sysfs dirent has been deleted */
290 if (sd->s_flags & SYSFS_FLAG_REMOVED)
293 /* The sysfs dirent has been moved? */
294 if (dentry->d_parent->d_fsdata != sd->s_parent)
297 /* The sysfs dirent has been renamed */
298 if (strcmp(dentry->d_name.name, sd->s_name) != 0)
301 /* The sysfs dirent has been moved to a different namespace */
302 if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
303 sysfs_info(dentry->d_sb)->ns != sd->s_ns)
306 mutex_unlock(&sysfs_mutex);
310 /* Remove the dentry from the dcache hashes.
311 * If this is a deleted dentry we use d_drop instead of d_delete
312 * so sysfs doesn't need to cope with negative dentries.
314 * If this is a dentry that has simply been renamed we
315 * use d_drop to remove it from the dcache lookup on its
316 * old parent. If this dentry persists later when a lookup
317 * is performed at its new name the dentry will be readded
318 * to the dcache hashes.
320 mutex_unlock(&sysfs_mutex);
322 /* If we have submounts we must allow the vfs caches
323 * to lie about the state of the filesystem to prevent
324 * leaks and other nasty things.
326 if (check_submounts_and_drop(dentry) != 0)
332 static void sysfs_dentry_release(struct dentry *dentry)
334 sysfs_put(dentry->d_fsdata);
337 const struct dentry_operations sysfs_dentry_ops = {
338 .d_revalidate = sysfs_dentry_revalidate,
339 .d_delete = sysfs_dentry_delete,
340 .d_release = sysfs_dentry_release,
343 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
345 char *dup_name = NULL;
346 struct sysfs_dirent *sd;
348 if (type & SYSFS_COPY_NAME) {
349 name = dup_name = kstrdup(name, GFP_KERNEL);
354 sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
358 if (sysfs_alloc_ino(&sd->s_ino))
361 atomic_set(&sd->s_count, 1);
362 atomic_set(&sd->s_active, 0);
366 sd->s_flags = type | SYSFS_FLAG_REMOVED;
371 kmem_cache_free(sysfs_dir_cachep, sd);
378 * sysfs_addrm_start - prepare for sysfs_dirent add/remove
379 * @acxt: pointer to sysfs_addrm_cxt to be used
381 * This function is called when the caller is about to add or remove
382 * sysfs_dirent. This function acquires sysfs_mutex. @acxt is used
383 * to keep and pass context to other addrm functions.
386 * Kernel thread context (may sleep). sysfs_mutex is locked on
389 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
390 __acquires(sysfs_mutex)
392 memset(acxt, 0, sizeof(*acxt));
394 mutex_lock(&sysfs_mutex);
398 * __sysfs_add_one - add sysfs_dirent to parent without warning
399 * @acxt: addrm context to use
400 * @sd: sysfs_dirent to be added
401 * @parent_sd: the parent sysfs_dirent to add @sd to
403 * Get @parent_sd and set @sd->s_parent to it and increment nlink of
404 * the parent inode if @sd is a directory and link into the children
405 * list of the parent.
407 * This function should be called between calls to
408 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
409 * passed the same @acxt as passed to sysfs_addrm_start().
412 * Determined by sysfs_addrm_start().
415 * 0 on success, -EEXIST if entry with the given name already
418 int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
419 struct sysfs_dirent *parent_sd)
421 bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
422 struct sysfs_inode_attrs *ps_iattr;
425 if (has_ns != (bool)sd->s_ns) {
426 WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
427 has_ns ? "required" : "invalid",
428 parent_sd->s_name, sd->s_name);
432 sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
433 sd->s_parent = sysfs_get(parent_sd);
435 ret = sysfs_link_sibling(sd);
439 /* Update timestamps on the parent */
440 ps_iattr = parent_sd->s_iattr;
442 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
443 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
446 /* Mark the entry added into directory tree */
447 sd->s_flags &= ~SYSFS_FLAG_REMOVED;
453 * sysfs_pathname - return full path to sysfs dirent
454 * @sd: sysfs_dirent whose path we want
455 * @path: caller allocated buffer of size PATH_MAX
457 * Gives the name "/" to the sysfs_root entry; any path returned
458 * is relative to wherever sysfs is mounted.
460 static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
463 sysfs_pathname(sd->s_parent, path);
464 strlcat(path, "/", PATH_MAX);
466 strlcat(path, sd->s_name, PATH_MAX);
470 void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name)
474 path = kzalloc(PATH_MAX, GFP_KERNEL);
476 sysfs_pathname(parent, path);
477 strlcat(path, "/", PATH_MAX);
478 strlcat(path, name, PATH_MAX);
481 WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s'\n",
488 * sysfs_add_one - add sysfs_dirent to parent
489 * @acxt: addrm context to use
490 * @sd: sysfs_dirent to be added
491 * @parent_sd: the parent sysfs_dirent to add @sd to
493 * Get @parent_sd and set @sd->s_parent to it and increment nlink of
494 * the parent inode if @sd is a directory and link into the children
495 * list of the parent.
497 * This function should be called between calls to
498 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
499 * passed the same @acxt as passed to sysfs_addrm_start().
502 * Determined by sysfs_addrm_start().
505 * 0 on success, -EEXIST if entry with the given name already
508 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
509 struct sysfs_dirent *parent_sd)
513 ret = __sysfs_add_one(acxt, sd, parent_sd);
516 sysfs_warn_dup(parent_sd, sd->s_name);
521 * sysfs_remove_one - remove sysfs_dirent from parent
522 * @acxt: addrm context to use
523 * @sd: sysfs_dirent to be removed
525 * Mark @sd removed and drop nlink of parent inode if @sd is a
526 * directory. @sd is unlinked from the children list.
528 * This function should be called between calls to
529 * sysfs_addrm_start() and sysfs_addrm_finish() and should be
530 * passed the same @acxt as passed to sysfs_addrm_start().
533 * Determined by sysfs_addrm_start().
535 static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
536 struct sysfs_dirent *sd)
538 struct sysfs_inode_attrs *ps_iattr;
541 * Removal can be called multiple times on the same node. Only the
542 * first invocation is effective and puts the base ref.
544 if (sd->s_flags & SYSFS_FLAG_REMOVED)
547 sysfs_unlink_sibling(sd);
549 /* Update timestamps on the parent */
550 ps_iattr = sd->s_parent->s_iattr;
552 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
553 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
556 sd->s_flags |= SYSFS_FLAG_REMOVED;
557 sd->u.removed_list = acxt->removed;
562 * sysfs_addrm_finish - finish up sysfs_dirent add/remove
563 * @acxt: addrm context to finish up
565 * Finish up sysfs_dirent add/remove. Resources acquired by
566 * sysfs_addrm_start() are released and removed sysfs_dirents are
570 * sysfs_mutex is released.
572 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
573 __releases(sysfs_mutex)
575 /* release resources acquired by sysfs_addrm_start() */
576 mutex_unlock(&sysfs_mutex);
578 /* kill removed sysfs_dirents */
579 while (acxt->removed) {
580 struct sysfs_dirent *sd = acxt->removed;
582 acxt->removed = sd->u.removed_list;
584 sysfs_deactivate(sd);
585 sysfs_unmap_bin_file(sd);
591 * sysfs_find_dirent - find sysfs_dirent with the given name
592 * @parent_sd: sysfs_dirent to search under
593 * @name: name to look for
594 * @ns: the namespace tag to use
596 * Look for sysfs_dirent with name @name under @parent_sd.
599 * mutex_lock(sysfs_mutex)
602 * Pointer to sysfs_dirent if found, NULL if not.
604 struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
605 const unsigned char *name,
608 struct rb_node *node = parent_sd->s_dir.children.rb_node;
609 bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
612 if (has_ns != (bool)ns) {
613 WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
614 has_ns ? "required" : "invalid",
615 parent_sd->s_name, name);
619 hash = sysfs_name_hash(name, ns);
621 struct sysfs_dirent *sd;
624 sd = to_sysfs_dirent(node);
625 result = sysfs_name_compare(hash, name, ns, sd);
627 node = node->rb_left;
629 node = node->rb_right;
637 * sysfs_get_dirent_ns - find and get sysfs_dirent with the given name
638 * @parent_sd: sysfs_dirent to search under
639 * @name: name to look for
640 * @ns: the namespace tag to use
642 * Look for sysfs_dirent with name @name under @parent_sd and get
646 * Kernel thread context (may sleep). Grabs sysfs_mutex.
649 * Pointer to sysfs_dirent if found, NULL if not.
651 struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
652 const unsigned char *name,
655 struct sysfs_dirent *sd;
657 mutex_lock(&sysfs_mutex);
658 sd = sysfs_find_dirent(parent_sd, name, ns);
660 mutex_unlock(&sysfs_mutex);
664 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
666 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
667 const char *name, const void *ns,
668 struct sysfs_dirent **p_sd)
670 umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
671 struct sysfs_addrm_cxt acxt;
672 struct sysfs_dirent *sd;
676 sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
681 sd->s_dir.kobj = kobj;
684 sysfs_addrm_start(&acxt);
685 rc = sysfs_add_one(&acxt, sd, parent_sd);
686 sysfs_addrm_finish(&acxt);
696 int sysfs_create_subdir(struct kobject *kobj, const char *name,
697 struct sysfs_dirent **p_sd)
699 return create_dir(kobj, kobj->sd, name, NULL, p_sd);
703 * sysfs_create_dir_ns - create a directory for an object with a namespace tag
704 * @kobj: object we're creating directory for
705 * @ns: the namespace tag to use
707 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
709 struct sysfs_dirent *parent_sd, *sd;
715 parent_sd = kobj->parent->sd;
717 parent_sd = &sysfs_root;
722 error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
728 static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
731 struct dentry *ret = NULL;
732 struct dentry *parent = dentry->d_parent;
733 struct sysfs_dirent *parent_sd = parent->d_fsdata;
734 struct sysfs_dirent *sd;
736 const void *ns = NULL;
738 mutex_lock(&sysfs_mutex);
740 if (parent_sd->s_flags & SYSFS_FLAG_NS)
741 ns = sysfs_info(dir->i_sb)->ns;
743 sd = sysfs_find_dirent(parent_sd, dentry->d_name.name, ns);
747 ret = ERR_PTR(-ENOENT);
750 dentry->d_fsdata = sysfs_get(sd);
752 /* attach dentry and inode */
753 inode = sysfs_get_inode(dir->i_sb, sd);
755 ret = ERR_PTR(-ENOMEM);
759 /* instantiate and hash dentry */
760 ret = d_materialise_unique(dentry, inode);
762 mutex_unlock(&sysfs_mutex);
766 const struct inode_operations sysfs_dir_inode_operations = {
767 .lookup = sysfs_lookup,
768 .permission = sysfs_permission,
769 .setattr = sysfs_setattr,
770 .getattr = sysfs_getattr,
771 .setxattr = sysfs_setxattr,
774 static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)
776 struct sysfs_dirent *last;
783 if (sysfs_type(pos) != SYSFS_DIR)
786 rbn = rb_first(&pos->s_dir.children);
790 pos = to_sysfs_dirent(rbn);
797 * sysfs_next_descendant_post - find the next descendant for post-order walk
798 * @pos: the current position (%NULL to initiate traversal)
799 * @root: sysfs_dirent whose descendants to walk
801 * Find the next descendant to visit for post-order traversal of @root's
802 * descendants. @root is included in the iteration and the last node to be
805 static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
806 struct sysfs_dirent *root)
810 lockdep_assert_held(&sysfs_mutex);
812 /* if first iteration, visit leftmost descendant which may be root */
814 return sysfs_leftmost_descendant(root);
816 /* if we visited @root, we're done */
820 /* if there's an unvisited sibling, visit its leftmost descendant */
821 rbn = rb_next(&pos->s_rb);
823 return sysfs_leftmost_descendant(to_sysfs_dirent(rbn));
825 /* no sibling left, visit parent */
826 return pos->s_parent;
829 static void __sysfs_remove(struct sysfs_addrm_cxt *acxt,
830 struct sysfs_dirent *sd)
832 struct sysfs_dirent *pos, *next;
837 pr_debug("sysfs %s: removing\n", sd->s_name);
842 next = sysfs_next_descendant_post(pos, sd);
844 sysfs_remove_one(acxt, pos);
849 * sysfs_remove - remove a sysfs_dirent recursively
850 * @sd: the sysfs_dirent to remove
852 * Remove @sd along with all its subdirectories and files.
854 void sysfs_remove(struct sysfs_dirent *sd)
856 struct sysfs_addrm_cxt acxt;
858 sysfs_addrm_start(&acxt);
859 __sysfs_remove(&acxt, sd);
860 sysfs_addrm_finish(&acxt);
864 * sysfs_hash_and_remove - find a sysfs_dirent by name and remove it
865 * @dir_sd: parent of the target
866 * @name: name of the sysfs_dirent to remove
867 * @ns: namespace tag of the sysfs_dirent to remove
869 * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
870 * it. Returns 0 on success, -ENOENT if such entry doesn't exist.
872 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name,
875 struct sysfs_addrm_cxt acxt;
876 struct sysfs_dirent *sd;
879 WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
884 sysfs_addrm_start(&acxt);
886 sd = sysfs_find_dirent(dir_sd, name, ns);
888 __sysfs_remove(&acxt, sd);
890 sysfs_addrm_finish(&acxt);
899 * sysfs_remove_dir - remove an object's directory.
902 * The only thing special about this is that we remove any files in
903 * the directory before we remove the directory, and we've inlined
904 * what used to be sysfs_rmdir() below, instead of calling separately.
906 void sysfs_remove_dir(struct kobject *kobj)
908 struct sysfs_dirent *sd = kobj->sd;
911 * In general, kboject owner is responsible for ensuring removal
912 * doesn't race with other operations and sysfs doesn't provide any
913 * protection; however, when @kobj is used as a symlink target, the
914 * symlinking entity usually doesn't own @kobj and thus has no
915 * control over removal. @kobj->sd may be removed anytime and
916 * symlink code may end up dereferencing an already freed sd.
918 * sysfs_symlink_target_lock synchronizes @kobj->sd disassociation
919 * against symlink operations so that symlink code can safely
920 * dereference @kobj->sd.
922 spin_lock(&sysfs_symlink_target_lock);
924 spin_unlock(&sysfs_symlink_target_lock);
927 WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
932 int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent_sd,
933 const char *new_name, const void *new_ns)
937 mutex_lock(&sysfs_mutex);
940 if ((sd->s_parent == new_parent_sd) && (sd->s_ns == new_ns) &&
941 (strcmp(sd->s_name, new_name) == 0))
942 goto out; /* nothing to rename */
945 if (sysfs_find_dirent(new_parent_sd, new_name, new_ns))
948 /* rename sysfs_dirent */
949 if (strcmp(sd->s_name, new_name) != 0) {
951 new_name = kstrdup(new_name, GFP_KERNEL);
956 sd->s_name = new_name;
960 * Move to the appropriate place in the appropriate directories rbtree.
962 sysfs_unlink_sibling(sd);
963 sysfs_get(new_parent_sd);
964 sysfs_put(sd->s_parent);
966 sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
967 sd->s_parent = new_parent_sd;
968 sysfs_link_sibling(sd);
972 mutex_unlock(&sysfs_mutex);
976 int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
979 struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
981 return sysfs_rename(kobj->sd, parent_sd, new_name, new_ns);
984 int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
987 struct sysfs_dirent *sd = kobj->sd;
988 struct sysfs_dirent *new_parent_sd;
990 BUG_ON(!sd->s_parent);
991 new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
992 new_parent_kobj->sd : &sysfs_root;
994 return sysfs_rename(sd, new_parent_sd, sd->s_name, new_ns);
998 * sysfs_enable_ns - enable namespace under a directory
999 * @sd: directory of interest, should be empty
1001 * This is to be called right after @sd is created to enable namespace
1002 * under it. All children of @sd must have non-NULL namespace tags and
1003 * only the ones which match the super_block's tag will be visible.
1005 void sysfs_enable_ns(struct sysfs_dirent *sd)
1007 WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
1008 WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
1009 sd->s_flags |= SYSFS_FLAG_NS;
1012 /* Relationship between s_mode and the DT_xxx types */
1013 static inline unsigned char dt_type(struct sysfs_dirent *sd)
1015 return (sd->s_mode >> 12) & 15;
1018 static int sysfs_dir_release(struct inode *inode, struct file *filp)
1020 sysfs_put(filp->private_data);
1024 static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
1025 struct sysfs_dirent *parent_sd, loff_t hash, struct sysfs_dirent *pos)
1028 int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
1029 pos->s_parent == parent_sd &&
1030 hash == pos->s_hash;
1035 if (!pos && (hash > 1) && (hash < INT_MAX)) {
1036 struct rb_node *node = parent_sd->s_dir.children.rb_node;
1038 pos = to_sysfs_dirent(node);
1040 if (hash < pos->s_hash)
1041 node = node->rb_left;
1042 else if (hash > pos->s_hash)
1043 node = node->rb_right;
1048 /* Skip over entries in the wrong namespace */
1049 while (pos && pos->s_ns != ns) {
1050 struct rb_node *node = rb_next(&pos->s_rb);
1054 pos = to_sysfs_dirent(node);
1059 static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
1060 struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos)
1062 pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
1065 struct rb_node *node = rb_next(&pos->s_rb);
1069 pos = to_sysfs_dirent(node);
1070 } while (pos && pos->s_ns != ns);
1074 static int sysfs_readdir(struct file *file, struct dir_context *ctx)
1076 struct dentry *dentry = file->f_path.dentry;
1077 struct sysfs_dirent *parent_sd = dentry->d_fsdata;
1078 struct sysfs_dirent *pos = file->private_data;
1079 const void *ns = NULL;
1081 if (!dir_emit_dots(file, ctx))
1083 mutex_lock(&sysfs_mutex);
1085 if (parent_sd->s_flags & SYSFS_FLAG_NS)
1086 ns = sysfs_info(dentry->d_sb)->ns;
1088 for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
1090 pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
1091 const char *name = pos->s_name;
1092 unsigned int type = dt_type(pos);
1093 int len = strlen(name);
1094 ino_t ino = pos->s_ino;
1095 ctx->pos = pos->s_hash;
1096 file->private_data = sysfs_get(pos);
1098 mutex_unlock(&sysfs_mutex);
1099 if (!dir_emit(ctx, name, len, ino, type))
1101 mutex_lock(&sysfs_mutex);
1103 mutex_unlock(&sysfs_mutex);
1104 file->private_data = NULL;
1109 static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
1111 struct inode *inode = file_inode(file);
1114 mutex_lock(&inode->i_mutex);
1115 ret = generic_file_llseek(file, offset, whence);
1116 mutex_unlock(&inode->i_mutex);
1121 const struct file_operations sysfs_dir_operations = {
1122 .read = generic_read_dir,
1123 .iterate = sysfs_readdir,
1124 .release = sysfs_dir_release,
1125 .llseek = sysfs_dir_llseek,