Re: [PATCH 0/3] NFS: Disable READ_PLUS by default

["Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>]

Hi Anna

I re-run bisect on your tree with tag nfs-for-5.10-1 as bad and 5.9.0 as good.

The bisect point to commit a14a63594cc2e5bdcbb1543d29df945da71e380f, which makes more sense.

[centos@os-46-nfs-devel linux-nfs]$ git bisect good
c567552612ece787b178e3b147b5854ad422a836 is the first bad commit
commit c567552612ece787b178e3b147b5854ad422a836
Author: Anna Schumaker <Anna.Schumaker@Netapp.com>
Date:   Wed May 28 13:41:22 2014 -0400

    NFS: Add READ_PLUS data segment support

    This patch adds client support for decoding a single NFS4_CONTENT_DATA
    segment returned by the server. This is the simplest implementation
    possible, since it does not account for any hole segments in the reply.

    Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

 fs/nfs/nfs42xdr.c         | 141 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/nfs/nfs4client.c       |   2 +
 fs/nfs/nfs4proc.c         |  43 +++++++++++++-
 fs/nfs/nfs4xdr.c          |   1 +
 include/linux/nfs4.h      |   2 +-
 include/linux/nfs_fs_sb.h |   1 +
 include/linux/nfs_xdr.h   |   2 +-
 7 files changed, 187 insertions(+), 5 deletions(-)


Best regards,
   Tigran

----- Original Message -----
> From: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
> To: "Olga Kornievskaia" <aglo@umich.edu>
> Cc: "schumaker anna" <schumaker.anna@gmail.com>, "linux-nfs" <linux-nfs@vger.kernel.org>, "Anna Schumaker"
> <Anna.Schumaker@netapp.com>
> Sent: Friday, 4 December, 2020 23:50:27
> Subject: Re: [PATCH 0/3] NFS: Disable READ_PLUS by default

> I agree with Olga, especially that disabling doesn't fixes my issue.
> Unfortunately I have no idea how kernel's vm works, but I am
> ready to test as many times as needed.
> 
> Thanks,
>   Tigran.
> 
> ----- Original Message -----
>> From: "Olga Kornievskaia" <aglo@umich.edu>
>> To: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
>> Cc: "schumaker anna" <schumaker.anna@gmail.com>, "linux-nfs"
>> <linux-nfs@vger.kernel.org>, "Anna Schumaker"
>> <Anna.Schumaker@netapp.com>
>> Sent: Friday, 4 December, 2020 21:00:32
>> Subject: Re: [PATCH 0/3] NFS: Disable READ_PLUS by default
> 
>> I object to putting the disable patch in, I think we need to fix the problem.
>> 
>> The current problem is generic/263 is failing because the end of the
>> buffer is corrupted since we lost the bytes when hole was expanded. I
>> don't know what the solution is: (1) hole expanding handling needs to
>> be fixed to not lose data or (2) we shouldnt be reporting that we read
>> the bytes we lost.
>> 
>> On Fri, Dec 4, 2020 at 10:49 AM Mkrtchyan, Tigran
>> <tigran.mkrtchyan@desy.de> wrote:
>>>
>>> Hi Anna,
>>>
>>> I see problems with gedeviceinfo and bisected it to
>>> c567552612ece787b178e3b147b5854ad422a836.
>>> The commit itself doesn't look that can break it, but might
>>> be can help you find the problem.
>>>
>>> What I see, that after xdr_read_pages call the xdr stream points
>>> to a some random point (or wrong page)
>>>
>>> Regards,
>>>    Tigran.
>>>
>>>
>>> ----- Original Message -----
>>> > From: "schumaker anna" <schumaker.anna@gmail.com>
>>> > To: "linux-nfs" <linux-nfs@vger.kernel.org>
>>> > Cc: "Anna Schumaker" <Anna.Schumaker@Netapp.com>
>>> > Sent: Thursday, 3 December, 2020 21:18:38
>>> > Subject: [PATCH 0/3] NFS: Disable READ_PLUS by default
>>>
>>> > From: Anna Schumaker <Anna.Schumaker@Netapp.com>
>>> >
>>> > I've been scratching my head about what's going on with xfstests generic/091
>>> > and generic/263, but I'm not sure what else to look at at this point.
>>> > This patchset disables READ_PLUS by default by marking it as a
>>> > developer-only kconfig option.
>>> >
>>> > I also included a couple of patches fixing some other issues that were
>>> > noticed while inspecting the code. These patches don't help the tests
>>> > pass, but they do fail later on after applying so it does feel like
>>> > progress.
>>> >
>>> > I'm hopeful the remaning issues can be worked out in the future.
>>> >
>>> > Thanks,
>>> > Anna
>>> >
>>> >
>>> > Anna Schumaker (3):
>>> >  NFS: Disable READ_PLUS by default
>>> >  NFS: Allocate a scratch page for READ_PLUS
>>> >  SUNRPC: Keep buf->len in sync with xdr->nwords when expanding holes
>>> >
>>> > fs/nfs/Kconfig          |  9 +++++++++
>>> > fs/nfs/nfs42xdr.c       |  2 ++
>>> > fs/nfs/nfs4proc.c       |  2 +-
>>> > fs/nfs/read.c           | 13 +++++++++++--
>>> > include/linux/nfs_xdr.h |  1 +
>>> > net/sunrpc/xdr.c        |  3 ++-
>>> > 6 files changed, 26 insertions(+), 4 deletions(-)
>>> >
>>> > --
> > > > 2.29.2