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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 53FF8C43219 for ; Thu, 2 May 2019 11:35:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E2C92075E for ; Thu, 2 May 2019 11:35:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726285AbfEBLfC (ORCPT ); Thu, 2 May 2019 07:35:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56860 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726283AbfEBLfC (ORCPT ); Thu, 2 May 2019 07:35:02 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D1A993078A1F; Thu, 2 May 2019 11:35:01 +0000 (UTC) Received: from coeurl.usersys.redhat.com (ovpn-122-85.rdu2.redhat.com [10.10.122.85]) by smtp.corp.redhat.com (Postfix) with ESMTP id 795245DA34; Thu, 2 May 2019 11:35:01 +0000 (UTC) Received: by coeurl.usersys.redhat.com (Postfix, from userid 1000) id CC5E9211FD; Thu, 2 May 2019 07:35:00 -0400 (EDT) Date: Thu, 2 May 2019 07:35:00 -0400 From: Scott Mayhew To: Trond Myklebust Cc: "bfields@fieldses.org" , "linux-nfs@vger.kernel.org" , "jlayton@kernel.org" Subject: Re: [PATCH] nfsd: CB_RECALL can race with FREE_STATEID Message-ID: <20190502113500.GH15226@coeurl.usersys.redhat.com> References: <20190418132400.24161-1-smayhew@redhat.com> <20190418151312.GB29274@fieldses.org> <20190418205024.GB15226@coeurl.usersys.redhat.com> <20190418213730.GA1891@fieldses.org> <20190430185845.GG15226@coeurl.usersys.redhat.com> <5ef90bd5ac79236458ffa04b7eb1d7812431859f.camel@hammerspace.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5ef90bd5ac79236458ffa04b7eb1d7812431859f.camel@hammerspace.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 02 May 2019 11:35:01 +0000 (UTC) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Tue, 30 Apr 2019, Trond Myklebust wrote: > On Tue, 2019-04-30 at 14:58 -0400, Scott Mayhew wrote: > > On Thu, 18 Apr 2019, J. Bruce Fields wrote: > > > > > On Thu, Apr 18, 2019 at 04:50:24PM -0400, Scott Mayhew wrote: > > > > On Thu, 18 Apr 2019, J. Bruce Fields wrote: > > > > > > > > > On Thu, Apr 18, 2019 at 09:24:00AM -0400, Scott Mayhew wrote: > > > > > > While trying to track down some issues involving large > > > > > > numbers of > > > > > > delegations being recalled/revoked, I caught the server > > > > > > setting > > > > > > SEQ4_STATUS_CB_PATH_DOWN while the client was actively > > > > > > responding to > > > > > > CB_RECALLs. It turns out that the client had already done a > > > > > > TEST_STATEID and FREE_STATEID for a delegation being recalled > > > > > > by the > > > > > > time it received the CB_RECALL. > > > > > > > > > > That's interesting, thanks! > > > > > > > > > > This exception seems awfully narrow, though. > > > > > > > > > > If we get back any NFS-level error at all, then I think the > > > > > callback > > > > > channel is working (am I wrong?) > > > > > > > > Correct, if the client replies with either NFS4ERR_DELAY or > > > > NFS4ERR_BAD_STATEID, the server will retry 1 time (see > > > > dl_retries). > > > > After that, we fall thru and nfsd4_cb_recall_done() returns -1 > > > > which > > > > causes the SEQ4_STATUS_CB_PATH_DOWN flag to be set. > > > > > > > > > and telling the client to set up a new > > > > > one is probably not going to help. The best we can do is > > > > > probably just > > > > > give up > > > > > > > > That's what the patch is essentially doing. Or are you saying > > > > don't > > > > even bother with the checks but still return 1 so we don't set > > > > the > > > > SEQ4_STATUS_CB_PATH_DOWN flag? > > > > > > Right, I don't see any point returning -1 (which ends up setting > > > CB_PATH_DOWN) in any case where we get an nfs-level error. If the > > > client got so far as returning an error, then the callback path is > > > working. > > > > > > I'm not sure exactly what errors *should* result in CB_PATH_DOWN, > > > though. ETIMEDOUT, ENOTCONN, EIO? > > > > I'm not sure either. Looking at > > call_status/call_timeout/rpc_check_timeout, it looks to me like > > ENOTCONN > > will be translated to ETIMEDOUT because nfsd4_run_cb_work sets the > > RPC_TASK_SOFTCONN flag in the call to rpc_call_async. > > > > It looks like call_status can return EHOSTDOWN, ENETDOWN, > > EHOSTUNREACH, > > ENETUNREACH, and EPERM... should those be handled as well? > > Those errors should never be passed back to applications. I'm confused. If call_status passes any of those errors to rpc_exit, then I'll see them in rpc_call_done/nfsd4_cb_done, won't I? -Scott > > -- > Trond Myklebust > Linux NFS client maintainer, Hammerspace > trond.myklebust@hammerspace.com > >