file_asynch_read (struct rw *rw,
                  struct command *command,
                  nbd_completion_callback cb)
{
  int dummy = 0;

  file_synch_read (rw, slice_ptr (command->slice),
                   command->slice.len, command->offset);
  /* file_synch_read called exit() on error */
  cb.callback (cb.user_data, &dummy);
}
file_asynch_read (struct rw *rw,
                  struct command *command,
                  nbd_completion_callback cb)
{
  int dummy = 0;

  file_synch_read (rw, slice_ptr (command->slice),
                   command->slice.len, command->offset);
   
  cb.callback (cb.user_data, &dummy);
}