[Samba] Oplock problem

[Boogerman]

Then, come to think of it, this oplock thing is dangerous (except for
read-only files). Even with good clients (bug free), this could still fail
in case of a network error or something.

I guess I will just disable oplocks (or else this will trouble my sleep).

I still wonder why M$ designed this mechanism if it was to bring such
problems. Furthermore, is there any way to implement failproof oplocks (not
over SMB, but in general)?

Regards,

Gaston Dassieu Blanchet
boogerman at interar.com.ar

----- Original Message -----
From: "John H Terpstra" <jht at samba.org>
To: "Boogerman" <boogerman at interar.com.ar>
Sent: Tuesday, May 06, 2003 11:05 PM
Subject: Re: [Samba] Oplock problem


> On Tue, 6 May 2003, Boogerman wrote:
>
> > John
> >
> > Yes, I had already read the Locking chapter of the HOWTO-Collection
(I've
> > been crawling trought the list archives seeking for a solution to my
problem
> > when I found a link to it).
> >
> > I found it very instructive. It describes very well what the types of
> > oplocks are and what they are used for. It's a real good work.
> >
> > I only have one question. At a certain point, you mention a "risk of
data
> > corruption". Can you explain me where this risk comes from? Is there a
flaw
> > in the oplock request/break mechanism?
>
> Clients can fail to see oplock break requests, the server then times out
> the lock, another client writes to the file, then the original client
> write to it also. Bang! Bad data!
>
> - John T.
>
> >
> > Regards,
> >
> > Gaston Dassieu Blanchet
> > boogerman at interar.com.ar
> >
> > ----- Original Message -----
> > From: "John H Terpstra" <jht at samba.org>
> > To: "Boogerman" <boogerman at interar.com.ar>
> > Cc: <samba at lists.samba.org>
> > Sent: Tuesday, May 06, 2003 2:13 PM
> > Subject: Re: [Samba] Oplock problem
> >
> >
> > > Gaston,
> > >
> > > There is a new chapter in the Samba-HOWTO-Collection.pdf (a work in
> > > progress) on locking. I'd appreciate your feedback on it and any
> > > suggestions you might make. Here is the URL for the in development
> > > version:
> > > http://samba.org/~jht/NT4migration/Samba-HOWTO-Collection.pdf
> > >
> > > - John T.
> > >
> > > On Tue, 6 May 2003, Boogerman wrote:
> > >
> > > > Hello everybody! I'm (again) after that 30 second lockup some of us
are
> > > > experiencing. Today, when I deleted the file pspbrwse.jbf, I
experienced
> > the
> > > > problem, and I immediately went to the logs. Here's what I got:
> > > >
> > > > [2003/05/06 11:06:50, 0] smbd/oplock.c:oplock_break(796)
> > > >   oplock_break: receive_smb timed out after 30 seconds.
> > > >   oplock_break failed for file htdocs/pictures/pspbrwse.jbf (dev =
901,
> > > > inode = 11009, file_id = 2654).
> > > > [2003/05/06 11:06:50, 0] smbd/oplock.c:oplock_break(868)
> > > >   oplock_break: client failure in oplock break in file
> > > > htdocs/pictures/pspbrwse.jbf
> > > > [2003/05/06 11:06:51, 0] smbd/reply.c:reply_lockingX(4626)
> > > >   reply_lockingX: Error : oplock break from client for fnum = 11670
and
> > no
> > > > oplock granted on this file (htdocs/pictures/pspbrwse.jbf).
> > > >
> > > > Ok, by the looks of it (anyone whith better knowledge of the SMB
> > protocol
> > > > and Samba internals, please correct me if I'm wrong), I would say
the
> > client
> > > > requested an oplock on pspbrowse.jbf, then when it deleted it, the
> > server
> > > > issued an oplock break request wich was unanswered by the client...
so
> > after
> > > > 30 seconds of receiving no answer, the server timed out the
operation.
> > So,
> > > > there appears to be a bug in the client (not responding to the
oplock
> > break
> > > > request). I must mention that the client is a Windows XP SP1.
> > > >
> > > > During those 30 seconds, the server didn't seem to respond to any
> > request
> > > > made by the client (that's why the client locked up). Other clients
> > worked
> > > > fine during those 30 seconds.
> > > >
> > > > Well, I have described what I think is the issue as best as I
could...
> > > > Apparently, It has nothing to do with WebDAV (I have already
disabled
> > it,
> > > > and it didn't fix anything).
> > > >
> > > > Any suggestions?
> > > >
> > > > Regards,
> > > >
> > > > Gaston Dassieu Blanchet
> > > > boogerman at interar.com.ar
> > > >
> > > >
> > > >
> > >
> > > --
> > > John H Terpstra
> > > Email: jht at samba.org
> > > --
> > > To unsubscribe from this list go to the following URL and read the
> > > instructions:  http://lists.samba.org/mailman/listinfo/samba
> > >
> > >
> > >
> >
> >
>
> --
> John H Terpstra
> Email: jht at samba.org
>
>