// OpenFileDirectIO - bypass kernel cache.
func OpenFileDirectIO(filePath string, flag int, perm os.FileMode) (*os.File, error) {
	return directio.OpenFile(filePath, flag, perm)
}

// DisableDirectIO - disables directio mode.
func DisableDirectIO(f *os.File) error {
	fd := f.Fd()
	_, err := unix.FcntlInt(fd, unix.F_NOCACHE, 0)
	return err
}

// AlignedBlock - pass through to directio implementation.

// OpenFileDirectIO - bypass kernel cache.
func OpenFileDirectIO(filePath string, flag int, perm os.FileMode) (*os.File, error) {
	return directio.OpenFile(filePath, flag, perm)
}

// DisableDirectIO - disables directio mode.
func DisableDirectIO(f *os.File) error {
	fd := f.Fd()
	flag, err := unix.FcntlInt(fd, unix.F_GETFL, 0)
	if err != nil {
		return err
	}
	flag &= ^(syscall.O_DIRECT)

// OpenFileDirectIO wrapper around os.OpenFile nothing special
func OpenFileDirectIO(filePath string, flag int, perm os.FileMode) (*os.File, error) {
	return os.OpenFile(filePath, flag, perm)
}

// DisableDirectIO is a no-op
func DisableDirectIO(f *os.File) error {
	return nil
}

// AlignedBlock simply returns an unaligned buffer
// for systems that do not support DirectIO.
func AlignedBlock(blockSize int) []byte {

			}

			// Disable O_DIRECT on fd's on unaligned buffer
			// perform an amortized Fdatasync(fd) on the fd at
			// the end, this is performed by the caller before
			// closing 'w'.
			if err = disk.DisableDirectIO(file); err != nil {
				return written, err
			}

			// buf is not aligned, hence use writeUnaligned()
			// for the remainder
			un, err = w.Write(buf[len(buf)-remain:])
			nw += int64(un)
		}