ovl_path_open
new_file = ovl_path_open(path, O_LARGEFILE | O_RDONLY);
old_file = ovl_path_open(&datapath, O_LARGEFILE | O_RDONLY);
new_file = ovl_path_open(temp, O_LARGEFILE | O_WRONLY);
struct file *ovl_path_open(const struct path *path, int flags);
realfile = ovl_path_open(realpath, O_RDONLY | O_LARGEFILE);
return ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));