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Date:   Tue, 6 Oct 2020 11:20:30 -0400
From:   Bruce Fields <bfields@fieldses.org>
To:     Dai Ngo <dai.ngo@oracle.com>
Cc:     linux-nfs@vger.kernel.org
Subject: Re: [PATCH 0/1] NFSv4.2: Fix NFS4ERR_STALE with inter server copy
Message-ID: <20201006152030.GC28306@fieldses.org>
References: <20200923230606.63904-1-dai.ngo@oracle.com>
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 <20201001205119.GI1496@fieldses.org>
 <9a60ba5b-aefe-d75b-683a-fa0f4db6ae24@oracle.com>
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On Thu, Oct 01, 2020 at 03:13:41PM -0700, Dai Ngo wrote:
> 
> On 10/1/20 2:52 PM, Bruce Fields wrote:
> >On Thu, Oct 01, 2020 at 02:48:07PM -0700, Dai Ngo wrote:
> >>Thanks Bruce for your comments,
> >>
> >>On 10/1/20 1:51 PM, Bruce Fields wrote:
> >>>On Tue, Sep 29, 2020 at 08:18:54PM -0700, Dai Ngo wrote:
> >>>>Have you had chance to review this patch and if it's ok would it be
> >>>>possible to include it in the 5.10 pull?
> >>>I don't think the op table approach would be that difficult, I'd really
> >>>rather see that.
> >>I think if we do the op table approach then we should also try to solve
> >>all other dependencies between various NFS client and server modules
> >>and not just the SSC part.
> >Are there any others?  I'd be very surprised.  It's something we've been
> >quite careful not to do in the past.  I apologize that it got past my
> >review this time.
> 
> No, I'm not sure if there is any others, I'm just being cautious.
> 
> We can always start by building the infra-structure and fix the SSC first
> and if there is any others then we can use the same mechanism to fix them
> too. I can work on this for long term. In the mean time can we pull in this
> temporary fix or you rather just want to see the long term solution?

I'd really rather see the long term solution.

--b.

> 
> 
> Thanks,
> -Dai
> 
> >
> >--b.
> >
> >>It might be a little involved so I'd like
> >>to take some time to research before committing to the longer solution
> >>which I plan to do. In the mean time, this small patch allows some of
> >>us to use the inter server copy until the long term solution is available.
> >>>Is this causing someone an immediate practical problem?
> >>This causes inter server copy to fail with any kernel build with NFS_FS=m
> >>which I think is a common config. And it also causes compile errors if
> >>NFSD=y, NFS_FS=y and NFS_v4=m.
> >>
> >>-Dai
> >>
> >>>--b.
> >>>
> >>>>Thanks,
> >>>>
> >>>>-Dai
> >>>>
> >>>>On 9/23/20 4:06 PM, Dai Ngo wrote:
> >>>>>This patch provides a temporarily relief for inter copy to work with
> >>>>>some common configs.  For long term solution, I think Trond's suggestion
> >>>>>of using fs/nfs/nfs_common to store an op table that server can use to
> >>>>>access the client code is the way to go.
> >>>>>
> >>>>>  fs/nfsd/Kconfig | 2 +-
> >>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>>
> >>>>>
> >>>>>Below are the results of my testing of upstream mainline without and with the fix.
> >>>>>
> >>>>>Upstream version used for testing:  5.9-rc5
> >>>>>
> >>>>>1. Upstream mainline (existing code: NFS_FS=y)
> >>>>>
> >>>>>
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|  NFSD  |  NFS_FS  |  NFS_V4  |               RESULTS                                   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    y     |    m     | Build errors: nfs42_ssc_open/close                      |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    m     |    m     | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|        |          |          | See NOTE1.                                              |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    m     |   y (m)  | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|        |          |          | See NOTE2.                                              |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    y     |    y     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>
> >>>>>
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|  NFSD  |  NFS_FS  |  NFS_V4  |               RESULTS                                   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    y     |    m     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    m     |    m     | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    m     |   y (m)  | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    y     |    y     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>
> >>>>>2. Upstream mainline (with the fix:  !(NFSD=y && (NFS_FS=m || NFS_V4=m))
> >>>>>
> >>>>>
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|  NFSD  |  NFS_FS  |  NFS_V4  |               RESULTS                                   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    y     |    m     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    m     |    m     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    m     |   y (m)  | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   m    |    y     |    y     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>
> >>>>>
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|  NFSD  |  NFS_FS  |  NFS_V4  |               RESULTS                                   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    y     |    m     | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    m     |    m     | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    m     |   y (m)  | Build OK, inter server copy failed with NFS4ERR_STALE   |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>|   y    |    y     |    y     | Build OK, inter server copy OK                          |
> >>>>>|----------------------------------------------------------------------------------------|
> >>>>>
> >>>>>NOTE1:
> >>>>>BUG:  When inter server copy fails with NFS4ERR_STALE, it left the file
> >>>>>created with size of 0!
> >>>>>
> >>>>>NOTE2:
> >>>>>When NFS_V4=y and NFS_FS=m, the build process automatically builds with NFS_V4=m
> >>>>>and ignores the setting NFS_V4=y in the config file.
> >>>>>
> >>>>>This probably due to NFS_V4 in fs/nfs/Kconfig is configured to depend on NFS_FS.
> >>>>>