[Cluster-devel] gfs uevent and sysfs changes

[David Teigland]

On Fri, Dec 05, 2008 at 09:51:45AM +0000, Steven Whitehouse wrote:
> In that case gfs2 should be able to generate the id itself from the
> fsname and it still doesn't need it passed in, even if it continues to
> expose the id in sysfs.
> 
> Perhaps better still, it should be possible for David to generate the id
> directly if he really needs it from the fsname.

It's not actually a crc of the fsname, but a crc of the cpg name
gfs_controld creates for the mountgroup, which is "gfs:mount:<fsname>".
Also, we may at some point want to allow that generated id to be overriden
by one that's set explicitly.

> worry about!), and I don't see that netlink should have any more
> overhead than any other method of sending messages.

netlink is painful compared to uevents, look at dlm_controld/netlink.c
which uses the "generic netlink" interface to transfer a data structure
from the kernel to userspace.  A library would help, but there didn't seem
to be a de facto netlink lib when I needed it, maybe that's changed.