Return-Path: Received: from mail-qk0-f173.google.com ([209.85.220.173]:36188 "EHLO mail-qk0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965651AbcKLMyO (ORCPT ); Sat, 12 Nov 2016 07:54:14 -0500 Received: by mail-qk0-f173.google.com with SMTP id n21so49455091qka.3 for ; Sat, 12 Nov 2016 04:54:13 -0800 (PST) Message-ID: <1478955250.2442.16.camel@redhat.com> Subject: Re: CLOSE/OPEN race From: Jeff Layton To: Benjamin Coddington , List Linux NFS Mailing Date: Sat, 12 Nov 2016 07:54:10 -0500 In-Reply-To: <9E2B8A0D-7B0E-4AE5-800A-0EF3F7F7F694@redhat.com> References: <9E2B8A0D-7B0E-4AE5-800A-0EF3F7F7F694@redhat.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sat, 2016-11-12 at 06:08 -0500, Benjamin Coddington wrote: > I've been seeing the following on a modified version of generic/089 > that gets the client stuck sending LOCK with NFS4ERR_OLD_STATEID. > > 1. Client has open stateid A, sends a CLOSE > 2. Client sends OPEN with same owner > 3. Client sends another OPEN with same owner > 4. Client gets a reply to OPEN in 3, stateid is B.2 (stateid B sequence 2) > 5. Client does LOCK,LOCKU,FREE_STATEID from B.2 > 6. Client gets a reply to CLOSE in 1 > 7. Client gets reply to OPEN in 2, stateid is B.1 > 8. Client sends LOCK with B.1 - OLD_STATEID, now stuck in a loop > > The CLOSE response in 6 causes us to clear NFS_OPEN_STATE, so that the OPEN > response in 7 is able to update the open_stateid even though it has a lower > sequence number. > > I think this case could be handled by never updating the open_stateid if the > stateids match but the sequence number of the new state is less than the > current open_state. > What kernel is this on? Yes, that seems wrong. The client should be picking B.2 for the open stateid to use. I think that decision of whether to take a seqid is made in nfs_need_update_open_stateid. The logic in there looks correct to me at first glance though. -- Jeff Layton