Currently the kobject based interface guarantees that a parent
sysfs_dirent is always a directory; however, the planned kernfs
interface will be directly based on sysfs_dirents and the caller may
specify non-directory node as the parent.  Add an explicit check in
__sysfs_add_one() so that such attempts fail with -EINVAL.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>