[PATCH 4/7] sysfs: Implement sysfs_rename_link

Eric W. Biederman
2010-01-11T20:22:40Z

From: Eric W. Biederman <ebiederm@xmission.com>

Because of rename ordering problems we occassionally give false
warnings about invalid sysfs operations. So using sysfs_rename
create a sysfs_rename_link function that doesn't need strange
workarounds.

Cc: Benjamin Thery <benjamin.thery@bull.net>
Cc: Daniel Lezcano <dlezcano@fr.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
fs/sysfs/symlink.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/sysfs.h | 9 +++++++++
2 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index c5eff49..1b9a3a1 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -123,6 +123,44 @@ void sysfs_remove_link(struct kobject * kobj, const char * name)
sysfs_hash_and_remove(parent_sd, name);
}

+/**
+ * sysfs_rename_link - rename symlink in object's directory.
+ * @kobj: object we're acting for.
+ * @targ: object we're pointing to.
+ * @old: previous name of the symlink.
+ * @new: new name of the symlink.
+ *
+ * A helper function for the common rename symlink idiom.
+ */
+int sysfs_rename_link(struct kobject *kobj, struct kobject *targ,
+ const char *old, const char *new)
+{
+ struct sysfs_dirent *parent_sd, *sd = NULL;
+ int result;
+
+ if (!kobj)
+ parent_sd = &sysfs_root;
+ else
+ parent_sd = kobj->sd;
+
+ result = -ENOENT;
+ sd = sysfs_get_dirent(parent_sd, old);
+ if (!sd)
+ goto out;
+
+ result = -EINVAL;
+ if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
+ goto out;
+ if (sd->s_symlink.target_sd->s_dir.kobj != targ)
+ goto out;
+
+ result = sysfs_rename(sd, parent_sd, new);
+
+out:
+ sysfs_put(sd);
+ return result;
+}
+
static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
struct sysfs_dirent *target_sd, char *path)
{
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index cfa8308..e322573 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -110,6 +110,9 @@ int __must_check sysfs_create_link_nowarn(struct kobject *kobj,
const char *name);
void sysfs_remove_link(struct kobject *kobj, const char *name);

+int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
+ const char *old_name, const char *new_name);
+
int __must_check sysfs_create_group(struct kobject *kobj,
const struct attribute_group *grp);
int sysfs_update_group(struct kobject *kobj,
@@ -203,6 +206,12 @@ static inline void sysfs_remove_link(struct kobject *kobj, const char *name)
{
}

+static inline int sysfs_rename_link(struct kobject *k, struct kobject *t,
+ const char *old_name, const char *new_name)
+{
+ return 0;
+}
+
static inline int sysfs_create_group(struct kobject *kobj,
const struct attribute_group *grp)
{
--
1.6.5.2.143.g8cc62