[Linux-cluster] new dlm control/configuration

[Patrick Caulfield]

On Thu, Mar 31, 2005 at 01:50:36PM -0800, Mark Fasheh wrote:
> Well it's actually quite clean in ocfs2_dlmfs, part of that is likely
> related to some design calls we made early on to simplify our userspace
> locking. We don't do ranges (anywhere really), and we consider all userspace
> lock requests to be synchronous. This does however result in a userspace API
> which is extremely lightweight and dirt simple to use.
> 
> mkdir gives you a new domain, files created within that directory correspond
> to lock resource with the same name. Open O_RDONLY gets you a PR mode lock,
> open RDWR gives you an EX mode lock. You can do NOQUEUE (trylock) ops with
> O_NONBLOCK. Reads and writes to the file return and set the LVB accordingly.
> 
> One can literally, create a domain, create locks within it and ship data via
> the LVB all from a bash shell on my cluster nodes.
> 
> I was able to write a trivial library wrapper (for those who don't want to
> use shell for controlling dlm functionality) in about 600 lines.
> 	--Mark
> 

That's interesting, thanks. As far as our DLM is concerned it's a very small
subset of the full functionality (so it would never replace the existing device
interface) but I can see it might be useful.

-- 

patrick