title: remount read-only with deleted file descriptors: Device or resource busy
body: <p>I need to update a running daemon on a read-only mounted ext4 file system. The device has been remounted read-write, if I modify the daemon (mv, cp), the process keeps running, but the file descriptor changes its state to "deleted".</p>
  
  <p>Now, it is not possible to remount the file system read-only anymore (device or resource busy), until the daemon process has been killed and the descriptor has been freed.</p>
  
  <p>Is there a way to keep the file descriptor valid while modifying the binary of a running process?</p>