Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:52686 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966565AbcKLSrC (ORCPT ); Sat, 12 Nov 2016 13:47:02 -0500 From: "Benjamin Coddington" To: "Trond Myklebust" Cc: "Linux List" Subject: Re: CLOSE/OPEN race Date: Sat, 12 Nov 2016 13:46:59 -0500 Message-ID: In-Reply-To: References: <9E2B8A0D-7B0E-4AE5-800A-0EF3F7F7F694@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: On 12 Nov 2016, at 13:16, Trond Myklebust wrote: > >> On Nov 12, 2016, at 06:08, 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. > > Hmm… We probably should not do that if the stateid.other field of A > (i.e. > the one supplied as the argument to CLOSE) does not match the > stateid.other of B. In fact, the reply in (4), where the stateid > changes > to B, should be the thing that resets the OPEN state. At 4, by reset the OPEN state, do you mean we should expect and wait for a pending close to complete, or we should start over with a brand new state? Maybe something else.. The reason the NFS_OPEN_STATE flag is cleared in 6 is that all the state counts (n_rdwr, n_rdonly, n_wronly) are zero. There could be a "pending open" flag or counter that would help 6 not clear NFS_OPEN_STATE..