2 * fs/sysfs/symlink.c - sysfs symlink 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.
14 #include <linux/module.h>
15 #include <linux/kobject.h>
16 #include <linux/mutex.h>
17 #include <linux/security.h>
21 static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
22 struct kobject *target,
23 const char *name, int warn)
25 struct sysfs_dirent *sd, *target_sd = NULL;
27 BUG_ON(!name || !parent_sd);
30 * We don't own @target and it may be removed at any time.
31 * Synchronize using sysfs_symlink_target_lock. See
32 * sysfs_remove_dir() for details.
34 spin_lock(&sysfs_symlink_target_lock);
36 target_sd = target->sd;
37 kernfs_get(target_sd);
39 spin_unlock(&sysfs_symlink_target_lock);
44 sd = kernfs_create_link(parent_sd, name, target_sd);
45 kernfs_put(target_sd);
50 if (warn && PTR_ERR(sd) == -EEXIST)
51 sysfs_warn_dup(parent_sd, name);
56 * sysfs_create_link_sd - create symlink to a given object.
57 * @sd: directory we're creating the link in.
58 * @target: object we're pointing to.
59 * @name: name of the symlink.
61 int sysfs_create_link_sd(struct sysfs_dirent *sd, struct kobject *target,
64 return sysfs_do_create_link_sd(sd, target, name, 1);
67 static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
68 const char *name, int warn)
70 struct sysfs_dirent *parent_sd = NULL;
73 parent_sd = sysfs_root_sd;
80 return sysfs_do_create_link_sd(parent_sd, target, name, warn);
84 * sysfs_create_link - create symlink between two objects.
85 * @kobj: object whose directory we're creating the link in.
86 * @target: object we're pointing to.
87 * @name: name of the symlink.
89 int sysfs_create_link(struct kobject *kobj, struct kobject *target,
92 return sysfs_do_create_link(kobj, target, name, 1);
94 EXPORT_SYMBOL_GPL(sysfs_create_link);
97 * sysfs_create_link_nowarn - create symlink between two objects.
98 * @kobj: object whose directory we're creating the link in.
99 * @target: object we're pointing to.
100 * @name: name of the symlink.
102 * This function does the same as sysfs_create_link(), but it
103 * doesn't warn if the link already exists.
105 int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
108 return sysfs_do_create_link(kobj, target, name, 0);
112 * sysfs_delete_link - remove symlink in object's directory.
113 * @kobj: object we're acting for.
114 * @targ: object we're pointing to.
115 * @name: name of the symlink to remove.
117 * Unlike sysfs_remove_link sysfs_delete_link has enough information
118 * to successfully delete symlinks in tagged directories.
120 void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
123 const void *ns = NULL;
126 * We don't own @target and it may be removed at any time.
127 * Synchronize using sysfs_symlink_target_lock. See
128 * sysfs_remove_dir() for details.
130 spin_lock(&sysfs_symlink_target_lock);
131 if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
133 spin_unlock(&sysfs_symlink_target_lock);
134 kernfs_remove_by_name_ns(kobj->sd, name, ns);
138 * sysfs_remove_link - remove symlink in object's directory.
139 * @kobj: object we're acting for.
140 * @name: name of the symlink to remove.
142 void sysfs_remove_link(struct kobject *kobj, const char *name)
144 struct sysfs_dirent *parent_sd = NULL;
147 parent_sd = sysfs_root_sd;
149 parent_sd = kobj->sd;
151 kernfs_remove_by_name(parent_sd, name);
153 EXPORT_SYMBOL_GPL(sysfs_remove_link);
156 * sysfs_rename_link_ns - rename symlink in object's directory.
157 * @kobj: object we're acting for.
158 * @targ: object we're pointing to.
159 * @old: previous name of the symlink.
160 * @new: new name of the symlink.
161 * @new_ns: new namespace of the symlink.
163 * A helper function for the common rename symlink idiom.
165 int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
166 const char *old, const char *new, const void *new_ns)
168 struct sysfs_dirent *parent_sd, *sd = NULL;
169 const void *old_ns = NULL;
173 parent_sd = sysfs_root_sd;
175 parent_sd = kobj->sd;
178 old_ns = targ->sd->s_ns;
181 sd = kernfs_find_and_get_ns(parent_sd, old, old_ns);
186 if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
188 if (sd->s_symlink.target_sd->priv != targ)
191 result = kernfs_rename_ns(sd, parent_sd, new, new_ns);
197 EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);