Function uapi::copy_file_range

pub fn copy_file_range(
    fd_in: c_int, 
    off_in: Option<&mut loff_t>, 
    fd_out: c_int, 
    off_out: Option<&mut loff_t>, 
    len: size_t, 
    flags: c_uint
) -> Result<usize>

copy_file_range(2)