Windowsでread_at, write_atが存在しない

[m5t0]

以下エラーメッセージ

error[E0599]: no method named `read_at` found for struct `File` in the current scope
  --> src\filemanager\file_mgr.rs:46:11
   |
46 |         f.read_at(p.contents().as_mut_slice(), blk.number() * blocksize as u64)?;
   |           ^^^^^^^ method not found in `File`

error[E0599]: no method named `write_at` found for struct `File` in the current scope
  --> src\filemanager\file_mgr.rs:54:11
   |
54 |         f.write_at(
   |           ^^^^^^^^ method not found in `File`

error[E0599]: no method named `write_at` found for struct `File` in the current scope
  --> src\filemanager\file_mgr.rs:69:11
   |
69 |         f.write_at(b, newblknum * blocksize as u64)?;
   |           ^^^^^^^^ method not found in `File`