in := io.Reader(hashReader)
			if size > encryptBufferThreshold {
				// The encryption reads in blocks of 64KB.
				// We add a buffer on bigger files to reduce the number of syscalls upstream.
				in = bufio.NewReaderSize(hashReader, encryptBufferSize)
			}
			reader, err = sio.EncryptReader(in, sio.Config{Key: partEncryptionKey[:], CipherSuites: fips.DARECiphers()})
			if err != nil {

		// Windows can lock up with this optimization, so we fall back to regular copy.
		sr, ok := rc.(*sendFileReader)
		if ok {
			// Sendfile sends in 4MiB chunks per sendfile syscall which is more than enough
			// for most setups.
			_, err = rf.ReadFrom(sr.Reader)
			if !xnet.IsNetworkOrHostDown(err, true) { // do not need to log disconnected clients
				storageLogIf(r.Context(), err)
			}