buf.Reset()
			bytebufferpool.Put(buf)
		}()

		md5w := md5.New()

		// Maximum allowed fan-out object size.
		const maxFanOutSize = 16 << 20

		n, err := io.Copy(io.MultiWriter(buf, md5w), ioutil.HardLimitReader(pReader, maxFanOutSize))
		if err != nil {
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}

		// Set the correct hex md5sum for the fan-out stream.