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Subject: Re: unsharing tcp connections from different NFS mounts
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <5B5CF80C-494A-42D3-8D3F-51C0277D9E1B@redhat.com>
Date:   Wed, 7 Oct 2020 09:45:50 -0400
Cc:     Bruce Fields <bfields@fieldses.org>,
        Olga Kornievskaia <aglo@umich.edu>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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References: <20201006151335.GB28306@fieldses.org>
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 <57E3293C-5C49-4A80-957B-E490E6A9B32E@redhat.com>
 <5B5CF80C-494A-42D3-8D3F-51C0277D9E1B@redhat.com>
To:     Benjamin Coddington <bcodding@redhat.com>
Precedence: bulk


> On Oct 7, 2020, at 8:55 AM, Benjamin Coddington <bcodding@redhat.com> =
wrote:
>=20
> On 7 Oct 2020, at 7:27, Benjamin Coddington wrote:
>=20
>> On 6 Oct 2020, at 20:18, J. Bruce Fields wrote:
>>=20
>>> On Tue, Oct 06, 2020 at 05:46:11PM -0400, Olga Kornievskaia wrote:
>>>> On Tue, Oct 6, 2020 at 3:38 PM Benjamin Coddington =
<bcodding@redhat.com> wrote:
>>>>>=20
>>>>> On 6 Oct 2020, at 11:13, J. Bruce Fields wrote:
>=20
>>> Looks like nfs4_init_{non}uniform_client_string() stores it in
>>> cl_owner_id, and I was thinking that meant cl_owner_id would be used
>>> from then on....
>>>=20
>>> But actually, I think it may run that again on recovery, yes, so I =
bet
>>> changing the nfs4_unique_id parameter midway like this could cause =
bugs
>>> on recovery.
>>=20
>> Ah, that's what I thought as well.  Thanks for looking closer Olga!
>=20
> Well, no -- it does indeed continue to use the original cl_owner_id.  =
We
> only jump through nfs4_init_uniquifier_client_string() if cl_owner_id =
is
> NULL:
>=20
> 6087 static int
> 6088 nfs4_init_uniform_client_string(struct nfs_client *clp)
> 6089 {
> 6090     size_t len;
> 6091     char *str;
> 6092
> 6093     if (clp->cl_owner_id !=3D NULL)
> 6094         return 0;
> 6095
> 6096     if (nfs4_client_id_uniquifier[0] !=3D '\0')
> 6097         return nfs4_init_uniquifier_client_string(clp);
> 6098
>=20
>=20
> Testing proves this out as well for both EXCHANGE_ID and SETCLIENTID.
>=20
> Is there any precedent for stabilizing module parameters as part of a
> supported interface?  Maybe this ought to be a mount option, so client =
can
> set a uniquifier per-mount.

The protocol is designed as one client-ID per client. FreeBSD is
the only client I know of that uses one client-ID per mount, fwiw.

You are suggesting each mount point would have its own lease. There
would likely be deeper implementation changes needed than just
specifying a unique client-ID for each mount point.

--
Chuck Lever