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From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     "J. Bruce Fields" <bfields@fieldses.org>
Cc:     "Olga Kornievskaia" <aglo@umich.edu>,
        linux-nfs <linux-nfs@vger.kernel.org>
Subject: Re: unsharing tcp connections from different NFS mounts
Date:   Wed, 07 Oct 2020 08:55:56 -0400
Message-ID: <5B5CF80C-494A-42D3-8D3F-51C0277D9E1B@redhat.com>
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On 7 Oct 2020, at 7:27, Benjamin Coddington wrote:

> On 6 Oct 2020, at 20:18, J. Bruce Fields wrote:
>
>> 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:
>>>>
>>>> On 6 Oct 2020, at 11:13, J. Bruce Fields wrote:

>> 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....
>>
>> 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.
>
> Ah, that's what I thought as well.  Thanks for looking closer Olga!

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:

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 != NULL)
6094         return 0;
6095
6096     if (nfs4_client_id_uniquifier[0] != '\0')
6097         return nfs4_init_uniquifier_client_string(clp);
6098


Testing proves this out as well for both EXCHANGE_ID and SETCLIENTID.

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.

Ben