}

		buf = buf[:nr]
		var (
			n  int
			un int
			nw int64
		)

		remain := len(buf) % DirectioAlignSize
		if remain == 0 {
			// buf is aligned for directio write()
			n, err = w.Write(buf)
			nw = int64(n)
		} else {
			if remain < len(buf) {
				n, err = w.Write(buf[:len(buf)-remain])
				if err != nil {
					return written, err
				}
				nw = int64(n)
			}