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From:   Xuewei Zhang <xueweiz@google.com>
Date:   Sat, 18 May 2019 19:15:32 -0700
Message-ID: <CAPtwhKoF0XTuFa5msGB_eiiwRcJA0kK7eu6Rw6-b-5+8Qy0DDw@mail.gmail.com>
Subject: Re: [PATCH] lockd: Show pid of lockd for remote locks
To:     Benjamin Coddington <bcodding@redhat.com>
Cc:     bfields@fieldses.org, Grigor Avagyan <grigora@google.com>,
        Trevor Bourget <bourget@google.com>,
        Nauman Rafique <nauman@google.com>,
        trond.myklebust@hammerspace.com, anna.schumaker@netapp.com,
        jlayton@kernel.org, linux-nfs@vger.kernel.org
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On Sat, May 18, 2019 at 5:09 AM Benjamin Coddington <bcodding@redhat.com> wrote:
>
> On 17 May 2019, at 17:45, Xuewei Zhang wrote:
> > Seems this patch introduced a bug in how lock protocol handles
> > GRANTED_MSG in nfs.
>
> Yes, you're right: it's broken, and broken badly because we find conflicting
> locks based on lockd's fl_pid and lockd's fl_owner, which is current->files.
> That means that clients are not differentiated, and that means that v3 locks
> are broken.

Thanks a lot for the quick response and confirming the problem!

>
> I'd really like to see the fl_pid value make sense on the server when we
> show it to userspace, so I think that we should stuff the svid in fl_owner.
>
> Clearly I need to be more careful making changes here, so I am going to take
> my time fixing this, and I won't get to it until Monday. A revert would get
> us back to safe behavior.

From my limited understanding, b8eee0e90f97 ("lockd: Show pid of lockd
for remote locks")
exists only for fixing lockd in 9d5b86ac13c5 ("fs/locks: Remove
fl_nspid and use fs-specific...").

But I don't see anything wrong in 9d5b86ac13c5 ("fs/locks: Remove
fl_nspid and use fs-specific..."). Could you let me know what's the
problem? Thanks a lot!

If 9d5b86ac13c5 ("fs/locks: Remove fl_nspid and use fs-specific...")
is correct, we
probably don't need to add another fixing patch. Perhaps reverting b8eee0e90f97
("lockd: Show pid of lockd for remote locks") would be the best way then.

>
> Ben

Best regards,
Xuewei