From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B79C0C55178 for ; Tue, 27 Oct 2020 17:34:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A1A920878 for ; Tue, 27 Oct 2020 17:34:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fieldses.org header.i=@fieldses.org header.b="VCAU3iRB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1814604AbgJ0Rei (ORCPT ); Tue, 27 Oct 2020 13:34:38 -0400 Received: from fieldses.org ([173.255.197.46]:45416 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1820106AbgJ0Rcz (ORCPT ); Tue, 27 Oct 2020 13:32:55 -0400 X-Greylist: delayed 427 seconds by postgrey-1.27 at vger.kernel.org; Tue, 27 Oct 2020 13:32:55 EDT Received: by fieldses.org (Postfix, from userid 2815) id 027E1C56; Tue, 27 Oct 2020 13:25:45 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 027E1C56 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1603819546; bh=5Zjl+grA86xTqQqsXe0cBYeVGDK3DUZbp8K34b8F+ug=; h=Date:To:Cc:Subject:References:In-Reply-To:From:From; b=VCAU3iRBiDkvpcl3RMA0NmgivltVE5ClXHZRHVBoOnLgx9w9asWTsrIyVa4TGs07W /WW4ZzDqQYUlXT2jq5h1jWV9UKEyIV4dzuh5+tWDZ7IVzcmr8/c8K6Sh1+6DubKXZB I7M6ex6x64ahA6oN5YdEOQu10NmtVpxUCNExozC0= Date: Tue, 27 Oct 2020 13:25:45 -0400 To: Chuck Lever Cc: Leon Romanovsky , Linux NFS Mailing List , linux-rdma@vger.kernel.org Subject: Re: [PATCH 00/20] NFSD support for multiple RPC/RDMA chunks Message-ID: <20201027172545.GB1644@fieldses.org> References: <160373843299.1886.12604782813896379719.stgit@klimt.1015granger.net> <20201027060823.GF4821@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Oct 27, 2020 at 09:24:54AM -0400, Chuck Lever wrote: > Hi Leon- > > > On Oct 27, 2020, at 2:08 AM, Leon Romanovsky wrote: > > > > On Mon, Oct 26, 2020 at 02:53:53PM -0400, Chuck Lever wrote: > >> This series implements support for multiple RPC/RDMA chunks per RPC > >> transaction. This is one of the few remaining generalities that the > >> Linux NFS/RDMA server implementation lacks. > >> > >> There is currently one known NFS/RDMA client implementation that can > >> send multiple chunks per RPC, and that is Solaris. Multiple chunks > >> are rare enough that the Linux NFS/RDMA implementation has been > >> successful without this support for many years. > > > > So why do we need it? Solaris is dead, and like you wrote Linux systems > > work without this feature just fine, what are the benefits? Who will use it? > > The Linux NFS implementation is living. We can add the ability > to provision multiple chunks per RPC to the Linux NFS client at > any time. > > Likewise any actively developed NFS/RDMA implementation can add > this feature. The RPC/RDMA version 1 protocol does not have the > ability to communicate the maximum number of chunks the server > will accept per RPC. > > Other server implementations do support multiple chunks per RPC. > The Linux NFS/RDMA server implementation has always been incomplete > in this regard. Can the client can detect the server's lack of support and fall back, or does the server's incompleteness violate the RFC in some way that can actually cause a failure to interoperate? --b. > And the Linux NFS server implementation (the non-transport specific > part) already supports multiple data payloads per NFSv4 COMPOUND. > > > Restoring a little more of the cover letter: > > >> Along with multiple chunk support, this series adds the following > >> benefits: > >> > >> - More robust input sanitization of RPC/RDMA headers > >> - An internal representation of chunks that is agnostic to their > >> wire format > > The Linux NFS/RDMA server implementation does need to have better > input sanitization. > > And there is a version 2 of RPC/RDMA under active development: > > https://datatracker.ietf.org/doc/draft-ietf-nfsv4-rpcrdma-version-two/ > > Having some protocol version agnosticism in our transport might > be necessary eventually. > > -- > Chuck Lever > >