[libvirt] Use flock() instead of fcntl()

[David Weber]

Am Freitag, 26. Juli 2013, 10:14:59 schrieb Daniel P. Berrange:
> On Fri, Jul 26, 2013 at 10:44:24AM +0200, David Weber wrote:
> > > Looking again at flock() I see it cannot support locking of ranges, only
> > > the entire file. This makes it unsuitable as a replacement for libvirt's
> > > use of fcntl() I'm afraid. I can only sugggest you configure OCFS2 so
> > > that it supports fcntl(), or setup virtlockd to use separate indirect
> > > leases on a diffrent shared filesystem, or perhaps try sanlock instead
> > > which doesn't require any special filesystem support.
> > 
> > It's true that flock() doesn't support locking of ranges but I can't see
> > how this is necessary.
> 
> The code may not currently use ranges, but that doesn't mean it'll stay
> that way. By adding support for flock() we're preventing us from making
> use of this feature in the future, and I don't want to see that.

Just curious,  what would be a possible feature which would require range 
based locking?

I would really like to see flock() support in virtlockd because all other 
solutions have major drawbacks for me.

> 
> Daniel