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.
func AlignedBlock(blockSize int) []byte {
	return directio.AlignedBlock(blockSize)

	if err != nil {
		return err
	}
	flag &= ^(syscall.O_DIRECT)
	_, err = unix.FcntlInt(fd, unix.F_SETFL, flag)
	return err
}

// AlignedBlock - pass through to directio implementation.
func AlignedBlock(blockSize int) []byte {
	return directio.AlignedBlock(blockSize)

	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 {
	return make([]byte, blockSize)

var (
	ODirectPoolLarge = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(LargeBlock)
			return &b
		},
	}
	ODirectPoolMedium = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(MediumBlock)
			return &b
		},
	}
	ODirectPoolSmall = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(SmallBlock)
			return &b
		},
	}
)

	xlStorageFormatFile = "xl.meta"

	// XL metadata file backup file carries previous per object metadata.
	xlStorageFormatFileBackup = "xl.meta.bkp"
)

var alignedBuf []byte

func init() {
	alignedBuf = disk.AlignedBlock(xioutil.DirectioAlignSize)
	_, _ = rand.Read(alignedBuf)
}

// isValidVolname verifies a volname name in accordance with object
// layer requirements.
func isValidVolname(volname string) bool {