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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Trond Myklebust <trondmy@hammerspace.com>
CC:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        "bcodding@redhat.com" <bcodding@redhat.com>,
        Anna Schumaker <anna.schumaker@netapp.com>
Subject: Re: [PATCH] NFSv4: Tune the race to set and use the client id
 uniquifier
Thread-Topic: [PATCH] NFSv4: Tune the race to set and use the client id
 uniquifier
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Date:   Mon, 28 Feb 2022 21:11:11 +0000
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> On Feb 28, 2022, at 3:42 PM, Trond Myklebust <trondmy@hammerspace.com> wr=
ote:
>=20
> On Mon, 2022-02-28 at 20:15 +0000, Chuck Lever III wrote:
>>=20
>>=20
>>> On Feb 28, 2022, at 3:06 PM, Trond Myklebust
>>> <trondmy@hammerspace.com> wrote:
>>>=20
>>> On Mon, 2022-02-28 at 19:04 +0000, Chuck Lever III wrote:
>>>>=20
>>>>=20
>>>>> On Feb 28, 2022, at 12:24 PM, Trond Myklebust
>>>>> <trondmy@hammerspace.com> wrote:
>>>>>=20
>>>>>> Attempts to work toward solutions in this area seem to be
>>>>>> ignored,
>>>>>> the
>>>>>> questions still stand.  Until we can sort out and agree on a
>>>>>> direction,
>>>>>> self-NACK to this patch.
>>>>>=20
>>>>> A new mount option doesn't solve any problems that we can't
>>>>> solve
>>>>> with
>>>>> the existing framework.
>>>>=20
>>>> I don't think a mount option was proposed. Rather, the mechanics
>>>> of the udev rule would be done by mount.nfs without any changes
>>>> to the administrative interface.
>>>>=20
>>>=20
>>> That's not how I read this proposal:
>>>=20
>>>> Do you still want us to keep this approach, or will you accept a
>>> mount
>>>> option as:
>>>> - first mount in a namespace sets the identifier
>>>> - subsequent mounts with conflicting identifiers return an error
>>>=20
>>>=20
>>> Which is why I responded as I did.
>>=20
>> Ah! Well, I read "mount option" as "mount alternative", I guess
>> I was filling in some context from previous dialog on the topic.
>>=20
>> I agree with you that an actual mount option -- that is, a new
>> administrative interface -- is not desirable or necessary.
>>=20
>> But I assert that having mount.nfs take care of initializing the
>> uniquifier for the net namespace is convenient, and can be done
>> automatically and reliably.
>>=20
>=20
> Again, if we do this, then I'd want the actual tool that initialises
> the uniquifier to be a separate one that gets called by mount if
> necessary.
> Otherwise we'll have to consider duplicating that code in busybox and
> all the other tools that have private implementations of 'mount'.

I don't have a problem with mount.nfs invoking a separate tool or
doing it as part of a systemd target that precedes remote-fs. The
tricky thing here seems to be guaranteeing that the uniquifier is
set before the first mount can be done.


--
Chuck Lever