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Date:   Wed, 7 Oct 2020 10:05:02 -0400
From:   Bruce Fields <bfields@fieldses.org>
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     Benjamin Coddington <bcodding@redhat.com>,
        Olga Kornievskaia <aglo@umich.edu>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: unsharing tcp connections from different NFS mounts
Message-ID: <20201007140502.GC23452@fieldses.org>
References: <20201006151335.GB28306@fieldses.org>
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On Wed, Oct 07, 2020 at 09:45:50AM -0400, Chuck Lever wrote:
> 
> 
> > On Oct 7, 2020, at 8:55 AM, Benjamin Coddington <bcodding@redhat.com> wrote:
> > 
> > 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.
> 
> 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.

Huh, I thought that should do it.

Do you have something specific in mind?

--b.