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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham 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 682E7C28CC0 for ; Thu, 30 May 2019 17:20:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F87E25E40 for ; Thu, 30 May 2019 17:20:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=umich.edu header.i=@umich.edu header.b="YlAr9P1/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726280AbfE3RUe (ORCPT ); Thu, 30 May 2019 13:20:34 -0400 Received: from mail-ua1-f67.google.com ([209.85.222.67]:38212 "EHLO mail-ua1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725961AbfE3RUe (ORCPT ); Thu, 30 May 2019 13:20:34 -0400 Received: by mail-ua1-f67.google.com with SMTP id r19so2780164uap.5 for ; Thu, 30 May 2019 10:20:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=umich.edu; s=google-2016-06-03; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=SRNAe5nZVFzqS2hNrlzK45aRm//CgTikkP457GNe26M=; b=YlAr9P1/p/DYs0V6g/78C+4RUDeVgDKhG0bC36mvKebNa1bos401uaKnOIH4FAT6xo rcimfV5Bcw3bdgmsp8HaNwZvBQckCvSvW5U9O5ngJgCbz/xmY7wIEGJwYC0pybBOFK5O vIjV8S3rHTm154t7wQzLSWlbU8LOGDrb1mZn4luXxu8e2gtrWjVOouoSQz6nih6rymf+ jz/7nZ6LFV0WQUmyYVeWJ9yKEGjXs5thX3yqknp89JVY98HmkFRu/EqlRoJbiI+KzgDI kw8EHCh2hpG59pEuKYDqkAZCN2q6uKfRW2ivdsYsE+UWxgBTMdpvKLb97jBUUq0aBSnF QSpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SRNAe5nZVFzqS2hNrlzK45aRm//CgTikkP457GNe26M=; b=IQKEo33xNd7LHmQu53MZbRcirAAzsIN5NsRPEaa0nI50uUwFE1hYAuHR9/RqXZ9VoO 21kSBnFCdQC+3nGyBKZhiL5pb3vb4iaoiCytLDizQnGG//tSjmtAOcPC11qzyX1kD0LL /5Mruo3VzAhBay8GO6Yorat75xslA54cx3qHgvGBNImECGnghBbbc/7Y/mofS/ipWj4y XMDricXm1uQPdTKh0fSLDRyY+soYXDGBVDA/2mCbpGELTP0p3s5LaPM1UQ1F1f2WV2Fs LfrE3mSNJepQdveUwHbPQuCMtPOcQPlmt3Fe+0IRah2/tGoxGlGBTnDmUpOWh54Y2/p9 Bqfw== X-Gm-Message-State: APjAAAWj2uW1HvsgXIb1Y9iIT1R0OpNhNDU6K5VxIsUra/BEuPVbrwjC O0+w0hnpoClDOAWQLRIayJCUbWch7UARqfkx7xk= X-Google-Smtp-Source: APXvYqwYky8FPHg3Jww2Sw5eGTDYW06u38rOQvq8BGynZpXidzewoZZcaGVjABC400IJIbVt91RYxVD4F+6NcxjALQs= X-Received: by 2002:ab0:2447:: with SMTP id g7mr2536361uan.65.1559236833510; Thu, 30 May 2019 10:20:33 -0700 (PDT) MIME-Version: 1.0 References: <155917564898.3988.6096672032831115016.stgit@noble.brown> <1df23ebc-ffe5-1a57-c40a-d5e9a45c8498@talpey.com> In-Reply-To: <1df23ebc-ffe5-1a57-c40a-d5e9a45c8498@talpey.com> From: Olga Kornievskaia Date: Thu, 30 May 2019 13:20:22 -0400 Message-ID: Subject: Re: [PATCH 0/9] Multiple network connections for a single NFS mount. To: Tom Talpey Cc: NeilBrown , Chuck Lever , Schumaker Anna , Trond Myklebust , linux-nfs Content-Type: text/plain; charset="UTF-8" Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Thu, May 30, 2019 at 1:05 PM Tom Talpey wrote: > > On 5/29/2019 8:41 PM, NeilBrown wrote: > > I've also re-arrange the patches a bit, merged two, and remove the > > restriction to TCP and NFSV4.x,x>=1. Discussions seemed to suggest > > these restrictions were not needed, I can see no need. > > I believe the need is for the correctness of retries. Because NFSv2, > NFSv3 and NFSv4.0 have no exactly-once semantics of their own, server > duplicate request caches are important (although often imperfect). > These caches use client XID's, source ports and addresses, sometimes > in addition to other methods, to detect retry. Existing clients are > careful to reconnect with the same source port, to ensure this. And > existing servers won't change. Retries are already bound to the same connection so there shouldn't be an issue of a retransmission coming from a different source port. > Multiple connections will result in multiple source ports, and possibly > multiple source addresses, meaning retried client requests may be > accepted as new, rather than having any chance of being recognized as > retries. > > NFSv4.1+ don't have this issue, but removing the restrictions would > seem to break the downlevel mounts. > > Tom. >