linux-kernel - Re: [PATCH v2] cifs: Silently ignore unknown oplock break handle

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Date:   Tue, 16 Mar 2021 23:06:45 +0530
From:   Rohith Surabattula <rohiths.msft@...il.com>
To:     Tom Talpey <tom@...pey.com>
Cc:     Vincent Whitchurch <vincent.whitchurch@...s.com>,
        Steve French <sfrench@...ba.org>,
        linux-cifs <linux-cifs@...r.kernel.org>, kernel@...s.com,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] cifs: Silently ignore unknown oplock break handle

This issue will not be seen once changes related to deferred close for
files is committed.
Currently, changes are in review. I will address review comments by this week.

Regards,
Rohith

On Tue, Mar 16, 2021 at 9:33 PM Tom Talpey <tom@...pey.com> wrote:
>
> On 3/16/2021 8:48 AM, Vincent Whitchurch via samba-technical wrote:
> > Make SMB2 not print out an error when an oplock break is received for an
> > unknown handle, similar to SMB1.  The SMB2 lease break path is not
> > affected by this patch.
> >
> > Without this, a program which writes to a file from one thread, and
> > opens, reads, and writes the same file from another thread triggers the
> > below errors several times a minute when run against a Samba server
> > configured with "smb2 leases = no".
> >
> >   CIFS: VFS: \\192.168.0.1 No task to wake, unknown frame received! NumMids 2
> >   00000000: 424d53fe 00000040 00000000 00000012  .SMB@...........
> >   00000010: 00000001 00000000 ffffffff ffffffff  ................
> >   00000020: 00000000 00000000 00000000 00000000  ................
> >   00000030: 00000000 00000000 00000000 00000000  ................
> >
> > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
> > ---
> >
> > Notes:
> >      v2:
> >      - Drop change to lease break
> >      - Rewrite commit message
> >
> >   fs/cifs/smb2misc.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
> > index 60d4bd1eae2b..4d8576e202e3 100644
> > --- a/fs/cifs/smb2misc.c
> > +++ b/fs/cifs/smb2misc.c
> > @@ -755,7 +755,7 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
> >       }
> >       spin_unlock(&cifs_tcp_ses_lock);
> >       cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
> > -     return false;
> > +     return true;
> >   }
> >
> >   void
> >
>
> As an oplock-only approach, it looks good. But the old cifs_dbg message
> "non-existent connection" is possibly misleading, since the connection
> may be perfectly fine.
>
> When breaking the loop successfully, the code emits
>         cifs_dbg(FYI, "file id match, oplock break\n");
> so perhaps
>         cifs_dbg(FYI, "No file id matched, oplock break ignored\n");
> ?
>
> Tom.