On Thu, Jan 8, 2015 at 9:37 PM, Anand Avati <avati@xxxxxxxxxxx> wrote:
Note that the mandatory locks available in the locks translator is just the mandatory extensions for posix locks - at least one of the apps must be using locks to begin with.
Linux mandatory locking definition seems to convey exactly the above meaning [1].
<extract>
4. Semantics ------------
1. Mandatory locks can only be applied via the fcntl()/lockf() locking interface - in other words the System V/POSIX interface. BSD style locks using flock() never result in a mandatory lock.</extract>
What Harmeet is asking for is something different - automatic exclusive access to edit files. i.e, if one app has opened a file for editing, other apps which attempt an open must either fail (EBUSY) or block till the first app closes. We need to treat open(O_RDONLY) as a read lock and open(O_RDWR|O_WRONLY) as a write lock request (essentially an auto applied oplock). This is something gluster does not yet have.ThanksOn Thu Jan 08 2015 at 2:49:29 AM Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx> wrote:
----- Original Message -----
> From: "Raghavendra Gowdappa" <rgowdapp@xxxxxxxxxx>
> To: "Harmeet Kalsi" <kharmeet@xxxxxxxxxxx>
> Cc: "Gluster-devel@xxxxxxxxxxx" <gluster-devel@xxxxxxxxxxx>
> Sent: Thursday, January 8, 2015 4:12:44 PM
> Subject: Re: mandatory lock
>
>
>
> ----- Original Message -----
> > From: "Harmeet Kalsi" <kharmeet@xxxxxxxxxxx>
> > To: "Gluster-devel@xxxxxxxxxxx" <gluster-devel@xxxxxxxxxxx>
> > Sent: Wednesday, January 7, 2015 5:55:43 PM
> > Subject: mandatory lock
> >
> > Dear All.
> > Would it be possible for someone to guide me in the right direction to
> > enable
> > the mandatory lock on a volume please.
> > At the moment two clients can edit the same file at the same time which is
> > causing issues.
>
> I see code related to mandatory locking in posix-locks xlator (pl_writev,
> pl_truncate etc). To enable it you've to set "option mandatory-locks yes" in
> posix-locks xlator loaded on bricks
> (/var/lib/glusterd/vols/<volname>/*.vol). We've no way to set this option
> through gluster cli. Also, I am not sure to what extent this feature is
> tested/used till now. You can try it out and please let us know whether it
> worked for you :).
If mandatory locking doesn't work for you, can you modify your application to use advisory locking, since advisory locking is tested well and being used for long time?
>
> > Many thanks in advance
> > Kind Regards
> >
> > _______________________________________________
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> > Gluster-devel@xxxxxxxxxxx
> > http://www.gluster.org/mailman/listinfo/gluster-devel
> >
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--
Raghavendra G
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