linux-kernel - Re: GFS2 file locking issues

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Message-ID: <20090211171816.GA14516@fogou.chygwyn.com>
Date:	Wed, 11 Feb 2009 17:18:16 +0000
From:	steve@...gwyn.com
To:	Kirill Kuvaldin <kirill.kuvaldin@...il.com>
Cc:	linux-cluster@...hat.com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: GFS2 file locking issues

Hi,

On Wed, Feb 11, 2009 at 05:37:11PM +0300, Kirill Kuvaldin wrote:
> On Wed, Feb 11, 2009 at 4:36 PM,  <steve@...gwyn.com> wrote:
> > Hi,
> >
> > On Wed, Feb 11, 2009 at 01:55:08PM +0300, Kirill Kuvaldin wrote:
> >> Hi,
> >>
> >> I'm trying to understand how the FS locking mechanism should work.
> >>
> >> I'm running a clustered GFS2 across two nodes, each node is a Xen domU.
> >> To check if locking works correctly I wrote the simple perl script below.
> >> Basically the script opens a file, locks it to prevent others from
> >> writing into it, writes 20 lines into it, then unlocks and closes.
> >>i
> >
> > It should be exactly the same on GFS and GFS2, after all the code for
> > flock is almost identical between the two. What mount options did you
> > use?
> 
> No specific options used, just mount -t gfs2 /dev/gfsc/lvol0 /gfs2...
> 
> > Which lock manager are you using - I presume lock_dlm?
> >
> 
> Yes, the FS was created using to be used with lock_dlm. I'm not sure
> if it is actually used for GFS2. How can I check that?
> 
> Kirill
cat /proc/mounts

It should be listed in the options. That will also tell you if localflocks
has been set as well. We do know of a bug in the GFS/GFS2 flock code though,
it ought to be using an interruptible wait and it doesn't at the moment.
Otherwise I don't know of any other issues.

Which kernel version are you using?

Steve.

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