[PATCH] s3: Avoid oplock break by storing timestamps with gpfs_set_times

[Christof Schmitt]

On Tue, Jan 07, 2014 at 05:19:21PM -0800, Jeremy Allison wrote:
> On Tue, Jan 07, 2014 at 02:58:24PM -0700, Christof Schmitt wrote:
> > >From 241e2865d11276688427ee3b1adbc0c0eb7d007a Mon Sep 17 00:00:00 2001
> > From: Christof Schmitt <cs at samba.org>
> > Date: Tue, 7 Jan 2014 11:55:46 -0700
> > Subject: [PATCH] s3: Avoid oplock break by storing timestamps with gpfs_set_times
> > 
> > The gpfs_set_times API call allows setting timestamps directly in GPFS
> > without going through the utime() call. Using this API call fixes an
> > unecessary oplock break when a client sends a SET_FILE_ALLOCATION_INFO
> > request and no other client has opened the file. The call to utime()
> > triggers the oplock break through the Linux kernel. Using the
> > gpfs_set_times call for updating the timestamp avoids the call to
> > utime() and the oplock break.
> 
> > Signed-off-by: Christof Schmitt <cs at samba.org>
> 
> LGTM.
> 
> Reviewed-by: Jeremy Allison <jra at samba.org>

Thank you, i will push it to autobuild.

> One question though - why don't use use gpfs_set_times()
> by default or just set gpfs:settimes = yes by default ?
> 
> I'm not sure why you want it off by default - any
> particular reason ?

I am not sure what you referring to. It is enabled by default, see the
comment in the manpage and the default setting for gpfs:settimes:

+               <command>yes(default)</command> - Use gpfs_set_times.
+               Fall back to utime and winattr when it is not available.
+               </para></listitem>


+       config->settimes = lp_parm_bool(SNUM(handle->conn), "gpfs",
+                                       "settimes", true);

It won't be used when the API call is not available on older GPFS
versions and it can be manually disabled (gpfs:settimes = no).

Christof