Request body: unbuffered reading. The r->request_body_no_buffering flag was introduced. It instructs client request body reading code to avoid reading the whole body, and to call post_handler early instead. The caller should use the ngx_http_read_unbuffered_request_body() function to read remaining parts of the body. Upstream module is now able to use this mode, if configured with the proxy_request_buffering directive.