samba - Sep 2011 - strict locking and kernel oplocks in the smb.conf

1) Does "strict locking = no" negate "kernel oplocks = yes"
?

2) What's the difference between the two?

3) What a good way to test if a file got a lock seen from the linux side and the
windows side?

4) If a file has a lock, does that mean you can still open the file in linux or
in windows, but can't write to it?

Any clarification between the two would be helpful.

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On Fri, Sep 30, 2011 at 11:28:43AM -0700, Philip Ong
wrote:
> 1) Does "strict locking = no" negate "kernel oplocks =
yes" ?
No.
> 2) What's the difference between the two?
One controls kernel oplocks, the other one controls whether smbd
checks SMB/SMB2/CIFS read/write requests against existing mandatory
locks.
> 3) What a good way to test if a file got a lock seen from the linux side
and the windows side?
cat /proc/locks

On windows, write a Win32 program.
> 4) If a file has a lock, does that mean you can still open the file in
linux or in windows, but can't write to it?
A lock from who ? CIFS/NFS/local process ?
> Any clarification between the two would be helpful.
Hope this helps.

No other process is accessing it. So any idea why it would work fine without
"strict locking = no" in previous kernels below 2.6.36.3?

-----Original Message-----
From: Jeremy Allison [jra at samba.org<mailto:jra at samba.org>]
Sent: Friday, September 30, 2011 03:09 PM Pacific Standard Time
To: Philip Ong
Cc: 'Jeremy Allison'; 'samba at lists.samba.org'
Subject: Re: [Samba] strict locking and kernel oplocks in the smb.conf



On Fri, Sep 30, 2011 at 11:48:52AM -0700, Philip Ong
wrote:
>
> Hope this helps.
> [Philip Ong] Thanks, yes, it does. I'm having a problem with being able
to copy a local
> Windows file to NFS area shared by samba on WinXP. If I set "strict
locking = no", I'm
> able to copy the file to the NFS area shared via samba. This seems to only
happen when
> upgrading from a kernel.org kernel of 2.6.36.3 and higher. I've tried
on Centos 4.5 and
> 5.6 and all seems to point to either kernel or samba mix (3.5.11 and 3.6).
I'd like to
> know the damage setting "strict locking = no" could possibly
cause especially since I'm
> not sure if I'd want to ignore mandatory locks. Is this going to be a
big problem? What
> are considered mandatory locks?
Actually you probably do want to ignore mandatory locks :-).

Is there another process accessing this file at the same
time ? If there is, and that process has taken a POSIX/NFS
lock out on the file, then "strict locking = yes" will
conflict.

More likely it's just an NFS bug in the locking code
though :-).

Jeremy.



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