Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2;
From:   Benjamin Coddington <bcodding@redhat.com>
To:     trond.myklebust@hammerspace.com, anna@kernel.org
Cc:     linux-nfs@vger.kernel.org
Subject: Re: [PATCH v2] NFSv4: fairly test all delegations on a SEQ4_
 revocation
Date:   Mon, 18 Sep 2023 16:36:03 -0400
Message-ID: <B39D8F7D-B852-42C9-BC1E-2DED2AC23ACA@redhat.com>
In-Reply-To: <D8B1F20B-E08D-4ED1-A0F5-0C2C763FEC88@redhat.com>
References: <426fa7ac71b4c9496039cc16169029a5abcb6dc5.1692902495.git.bcodding@redhat.com>
 <6c85bc9cc6bd8d70fe0e74b096c72944f61874a7.1692903063.git.bcodding@redhat.com>
 <D8B1F20B-E08D-4ED1-A0F5-0C2C763FEC88@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On 14 Sep 2023, at 9:18, Benjamin Coddington wrote:

> On 24 Aug 2023, at 14:52, Benjamin Coddington wrote:
>
>> When the client is required to use TEST_STATEID to discover which
>> delegation(s) have been revoked, it may continually test delegations at the
>> head of the list if the server continues to be unsatisfied and send
>> SEQ4_STATUS_RECALLABLE_STATE_REVOKED.  For a large number of delegations
>> this behavior is prone to live-lock because the client may never be able to
>> test and free revoked state at the end of the list since the
>> SEQ4_STATUS_RECALLABLE_STATE_REVOKED will cause us to flag delegations at
>> the head of the list to be tested.  This problem is further exacerbated by
>> the state manager's willingness to be scheduled out on a busy system while
>> testing the list of delegations.
>>
>> Keep a generation counter for each attempt to test all delegations, and
>> skip delegations that have already been tested in the current pass.
>>
>> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>
> This one went through the ringer in an environment that saw multiple clients
> live-locking, and resolves the problem for them.  They asked me to add:
>
> Tested-by: Torkil Svensgaard <torkil@drcmr.dk>
> Tested-by: Ruben Vestergaard <rubenv@drcmr.dk>
>
> Ben

Did this one get rejected with a reason?  This fix could also be implemented
with flag (as I mentioned in a reply on v2).

Ben