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From:   Benjamin Coddington <bcodding@redhat.com>
To:     Jeff Layton <jlayton@kernel.org>
Cc:     Chuck Lever <chuck.lever@oracle.com>, linux-nfs@vger.kernel.org
Subject: Re: [PATCH] nfsd: Fix race to FREE_STATEID and cl_revoked
Date:   Fri, 04 Aug 2023 11:35:12 -0400
Message-ID: <2F29BA80-0545-4AD3-8C18-109AA32CC144@redhat.com>
In-Reply-To: <7e6053d48b2e4d62c7875e76653ecbc7557ec8d4.camel@kernel.org>
References: <c0fe2b35900938943048340ef70fc12282fe1af8.1691160604.git.bcodding@redhat.com>
 <ZM0TF/rOFOxlaA+p@tissot.1015granger.net>
 <7e6053d48b2e4d62c7875e76653ecbc7557ec8d4.camel@kernel.org>
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On 4 Aug 2023, at 11:33, Jeff Layton wrote:

> On Fri, 2023-08-04 at 11:02 -0400, Chuck Lever wrote:
>> On Fri, Aug 04, 2023 at 10:52:20AM -0400, Benjamin Coddington wrote:
>>> We have some reports of linux NFS clients that cannot satisfy a linux knfsd
>>> server that always sets SEQ4_STATUS_RECALLABLE_STATE_REVOKED even though
>>> those clients repeatedly walk all their known state using TEST_STATEID and
>>> receive NFS4_OK for all.
>>>
>>> Its possible for revoke_delegation() to set NFS4_REVOKED_DELEG_STID, then
>>> nfsd4_free_stateid() finds the delegation and returns NFS4_OK to
>>> FREE_STATEID.  Afterward, revoke_delegation() moves the same delegation to
>>> cl_revoked.  This would produce the observed client/server effect.
>>>
>>> Fix this by ensuring that the setting of sc_type to NFS4_REVOKED_DELEG_STID
>>> and move to cl_revoked happens within the same cl_lock.  This will allow
>>> nfsd4_free_stateid() to properly remove the delegation from cl_revoked.
>>>
>>> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2217103
>>> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2176575
>>> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>>
>> Hi Ben, does this fix deserve:
>>
>> Cc: stable@vger.kernel.org # v4.17+
>>
>> ??
>>
>
> What's special about v4.17? Is there a patch that broke it that went
> into that release?

Before 0af6e690f0d4e the patch won't apply.

Ben