On Sat, Sep 03, 2005 at 10:41:40PM -0700, Andrew Morton wrote: > Joel Becker <Joel.Becker@xxxxxxxxxx> wrote: > > > > > What happens when we want to add some new primitive which has no > > > posix-file analog? > > > > The point of dlmfs is not to express every primitive that the > > DLM has. dlmfs cannot express the CR, CW, and PW levels of the VMS > > locking scheme. Nor should it. The point isn't to use a filesystem > > interface for programs that need all the flexibility and power of the > > VMS DLM. The point is a simple system that programs needing the basic > > operations can use. Even shell scripts. > > Are you saying that the posix-file lookalike interface provides access to > part of the functionality, but there are other APIs which are used to > access the rest of the functionality? If so, what is that interface, and > why cannot that interface offer access to 100% of the functionality, thus > making the posix-file tricks unnecessary? We're using our dlm quite a bit in user space and require the full dlm API. It's difficult to export the full API through a pseudo fs like dlmfs, so we've not found it a very practical approach. That said, it's a nice idea and I'd be happy if someone could map a more complete dlm API onto it. We export our full dlm API through read/write/poll on a misc device. All user space apps use the dlm through a library as you'd expect. The library communicates with the dlm_device kernel module through read/write/poll and the dlm_device module talks with the actual dlm: linux/drivers/dlm/device.c If there's a better way to do this, via a pseudo fs or not, we'd be pleased to try it. Dave -- Linux-cluster@xxxxxxxxxx http://www.redhat.com/mailman/listinfo/linux-cluster
