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=-5.8 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 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 3FBFCC11F66 for ; Tue, 29 Jun 2021 13:48:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D82461DC4 for ; Tue, 29 Jun 2021 13:48:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234038AbhF2Nu4 (ORCPT ); Tue, 29 Jun 2021 09:50:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233050AbhF2Nux (ORCPT ); Tue, 29 Jun 2021 09:50:53 -0400 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [IPv6:2a00:1450:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25EFDC061760 for ; Tue, 29 Jun 2021 06:48:24 -0700 (PDT) Received: by mail-ed1-x52a.google.com with SMTP id i24so31378846edx.4 for ; Tue, 29 Jun 2021 06:48:24 -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=oPY8XUsbQs34luJ1j/FZlv4+IRmgrVaRyluyReYT/HM=; b=LFw6vVp38NRTCIYJ5kqYbg3XAONp4B4GDnpy0cJRDoxIt04CYJJ7rov59Y+AP8XEUT q8kaZ/mM4WWqlBfOr053LA+/5NmNqsltmZDisg0qReEPTMXWMU+F6PMatNpqnU5iuyHk 1px2irNW0fERM0kFX3MAGiXX6E2eQusNk8InhefGUTXqPQZTkzCNHkcYI4Xw9q4XCNEZ ccLZYruYzja+RlPFuI9CG7B7duscEBptla1Zj7U/gybexMp6msZ2iKecHutoG9rVf8jp MHw3dMX2SajG0XcnHU/eyPKT+0/sf1YBouMD1RZLWKjuzRsrj1w6wZPyjY2ny8bFLUy6 Qi9Q== 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=oPY8XUsbQs34luJ1j/FZlv4+IRmgrVaRyluyReYT/HM=; b=khVFlEj5w5rdRwPiniZWsbL2q+8yLBQRPWYk9D3cYPX7zTufFhaFJsOt0t5XQF/tgH W+y/d7bmIorK/D/3BtlKXeFhijQ2SC1DOaX2jSGSeQKa3wg9vinK1qnlFA4z2DEcdUPX 9y4zjR8qreZ5zCDK36Z0zsbJLsE5cfmm6Nn0LLvDl5xTQbzyXe1WF7zll0vGJxAd6qe6 06UtE00P+Nwtt/sRMM0IPqFiMfaz1RKN/yc287eCMLVqpi4zFcw9wMqXcXYmmpP9wLJr gEbS5xD7ljRZC8KGet94M3lQ0frq0k9XonTxIWkuW3qKdAbaq1ox1ivGce+SovXEGTw5 CxSw== X-Gm-Message-State: AOAM533JXzuHmL9+WJQBQAxqGthtOcB6LtkJjEdukNwri82+KjgJkirm H5mCFYPhhvHdwYGszFQElHBwfnijcCOE6bW3URQ= X-Google-Smtp-Source: ABdhPJx1woJjWHEPZylgUdHHTA9Xt11I+KXJjOzKNc76KJBukFTlhfaLIM8xbeCaYqO3aXQHipVbfLDvT02giggAaR4= X-Received: by 2002:a05:6402:148d:: with SMTP id e13mr1496420edv.28.1624974502555; Tue, 29 Jun 2021 06:48:22 -0700 (PDT) MIME-Version: 1.0 References: <81154dc28d528402bf5e090a81e6892c7abc431c.camel@hammerspace.com> In-Reply-To: From: Olga Kornievskaia Date: Tue, 29 Jun 2021 09:48:11 -0400 Message-ID: Subject: Re: client's caching of server-side capabilities To: Chuck Lever III Cc: Trond Myklebust , Linux NFS Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Tue, Jun 29, 2021 at 8:58 AM Chuck Lever III wrote: > > > > > On Jun 28, 2021, at 6:06 PM, Trond Myklebust wrote: > > > > On Mon, 2021-06-28 at 16:23 -0400, Olga Kornievskaia wrote: > >> Hi folks, > >> > >> I have a general question of why the client doesn't throw away the > >> cached server's capabilities on server reboot. Say a client mounted a > >> server when the server didn't support security_labels, then the > >> server > >> was rebooted and support was enabled. Client re-establishes its > >> clientid/session, recovers state, but assumes all the old > >> capabilities > >> apply. A remount is required to clear old/find new capabilities. The > >> opposite is true that a capability could be removed (but I'm assuming > >> that's a less practical example). > >> > >> I'm curious what are the problems of clearing server capabilities and > >> rediscovering them on reboot? Is it because a local filesystem could > >> never have its attributes changed and thus a network file system > >> can't > >> either? > >> > >> Thank you. > > > > In my opinion, the client should aim for the absolute minimum overhead > > on a server reboot. The goal should be to recover state and get I/O > > started again as quickly as possible. > > I 100% agree with the above. However... > > > > Detection of new features, etc > > can wait until the client needs to restart. > > A server reboot can be part of a failover to a different server. I > think capability discovery needs to happen as part of server reboot > recovery, it can't be optimized away. Can you clarify what you mean by a "failover to a different server"? To do reboot recovery it has to be the "same" server (by the definitions of the RFC). My use case I was thinking of was a reboot of the "same" server (major, minor, scope same) but with new features but of course one could argue if it has new features it's no longer the "same" server. I think you are probably thinking about migration or are you thinking of telling a difference between session trunkable servers which are considered to be the same but since it's a different IP it might have different capabilities? Thank you for the feedback! > > > -- > Chuck Lever > > >