Right now the code uses make_buffer_input_stream() helper that creates an input stream with buffer_data_source_impl inside which, in turn, provides the data_source_impl API over a single temporary_buffer. Seastar has the very same facility, it's better to use it. Eventually the buffer_data_source_impl will be removed. Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>