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Subject: Re: [PATCH 0/3] Handling NFSv3 I/O errors in knfsd
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <ed2a86da204cbf644ef2dada4bda2b899da48764.camel@redhat.com>
Date:   Wed, 28 Aug 2019 09:57:25 -0400
Cc:     Bruce Fields <bfields@fieldses.org>,
        Trond Myklebust <trondmy@hammerspace.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Bruce Fields <bfields@redhat.com>
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To:     Jeff Layton <jlayton@redhat.com>
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> On Aug 28, 2019, at 9:51 AM, Jeff Layton <jlayton@redhat.com> wrote:
> 
> On Wed, 2019-08-28 at 09:48 -0400, bfields@fieldses.org wrote:
>> On Tue, Aug 27, 2019 at 03:15:35PM +0000, Trond Myklebust wrote:
>>> I'm open to other suggestions, but I'm having trouble finding one that
>>> can scale correctly (i.e. not require per-client tracking), prevent
>>> silent corruption (by causing clients to miss errors), while not
>>> relying on optional features that may not be implemented by all NFSv3
>>> clients (e.g. per-file write verifiers are not implemented by *BSD).
>>> 
>>> That said, it seems to me that to do nothing should not be an option,
>>> as that would imply tolerating silent corruption of file data.
>> 
>> So should we increment the boot verifier every time we discover an error
>> on an asynchronous write?
>> 
> 
> I think so. Otherwise, only one client will ever see that error.

+1

I'm not familiar with the details of how the Linux NFS server
implements the boot verifier: Will a verifier bump be effective
for all file systems that server exports? If so, is that an
acceptable cost?


--
Chuck Lever