sysfs: remove ktype->namespace() invocations in symlink code

There's no reason for sysfs to be calling ktype->namespace().  It is
backwards, obfuscates what's going on and unnecessarily tangles two
separate layers.

There are two places where symlink code calls ktype->namespace().

* sysfs_do_create_link_sd() calls it to find out the namespace tag of
  the target directory.  Unless symlinking races with cross-namespace
  renaming, this equals @target_sd->s_ns.

* sysfs_rename_link() uses it to find out the new namespace to rename
  to and the new namespace can be different from the existing one.
  The function is renamed to sysfs_rename_link_ns() with an explicit
  @ns argument and the ktype->namespace() invocation is shifted to the
  device layer.

While this patch replaces ktype->namespace() invocation with the
recorded result in @target_sd, this shouldn't result in any behvior
difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 7f56bad3be82..c792f73ac7fa 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -213,8 +213,9 @@ 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 sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
+			 const char *old_name, const char *new_name,
+			 const void *new_ns);
 
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
@@ -340,8 +341,9 @@ 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)
+static inline int sysfs_rename_link_ns(struct kobject *k, struct kobject *t,
+				       const char *old_name,
+				       const char *new_name, const void *ns)
 {
 	return 0;
 }
@@ -454,4 +456,10 @@ static inline void sysfs_remove_file(struct kobject *kobj,
 	return sysfs_remove_file_ns(kobj, attr, NULL);
 }
 
+static inline int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
+				    const char *old_name, const char *new_name)
+{
+	return sysfs_rename_link_ns(kobj, target, old_name, new_name, NULL);
+}
+
 #endif /* _SYSFS_H_ */