ovl_path_real
type = ovl_path_real(dentry, &realpath);
ovl_path_real(dentry, &upperpath);
ovl_path_real(dentry, &realpath);
ovl_path_real(dentry, &metapath);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
type = ovl_path_real(file->f_path.dentry, &realpath);
ovl_path_real(root_dentry, &path);