Function is_terminal_error

src/copy.c:220–224

   and even though !is_CLONENOTSUP (ERR).  */

static bool
is_terminal_error (int err)
{
  return err == EIO || err == ENOMEM || err == ENOSPC || err == EDQUOT;
}

/* Perform the O(1) btrfs clone operation, if possible.
   Upon success, return 0.  Otherwise, return -1 and set errno.  */