[Cluster-devel] Re: Groupd uevent clean up

[David Teigland <teigland@redhat.com>]

On Tue, Nov 25, 2008 at 02:08:42PM +0000, Steven Whitehouse wrote:
> 
> The following patch is designed to clean up a number of items relating to
> gfs_controld's handling of uevent notifications. When a uevent is received
> is consists of a number of strings whose total length is bounded by the
> buffer size and returned by the recv call.
> 
> Originally only the initial string was being used to select the various
> actions. That was wrong for various reasons, but mostly because its much
> easier to simply look for the individual fields, broken out from the
> message. The other reason that this is wrong, and also the reason that
> I started looking into this area initially is that the initial event
> string provides a "physical" view of the event. By using the SUBSYSTEM=
> field, we get the same information, but it can also be overridden by
> the kernel using the kset_uevent_ops which will become important when
> we merge the lock_dlm module into GFS2.
> 
> The other problem (unsolved here) is that we have to parse the fs name
> from the DEVPATH= variable. Its trivial to add a feature to the kernel
> to provide the LOCKTABLE as well, so I plan to do that in the future
> so we don't have to jump through hoops to get that information.
> 
> At the same time I've marked a bunch of variables const. Mainly
> because they started to throw up warnings after I'd added the
> new event parsing code.
> 
> I've tested the parsing code on its own, but since I don't have the
> right packages installed here, I've not had a chance to build &
> test a complete new groupd yet.

OK, thanks, I dislike the const sprinkling, and I don't care about string
parsing.  I'll take your word that this string parsing is an improvement
over what's there (I really dislike string parsing, previously get_args()
was used for splitting args from other strings, too).  All I know is that
what's there works, so if you can verify that the new parsing really works
I'll add it (or I can do a quick test if you resend a patch with just that
bit).

> Also, I've fixed up some broken error handling in process_uevent
> at the same time.

Yep, good catch, I'll add that small bit right now.

> +/* FIXME: All of the below functions call find_mg as pretty much
> + * the first thing that they do. This ought to be done here and
> + * the found mg (if any) passed to the routines.
> + */

It didn't work out well last time I tried that, one of the main sticking
points was that the "old" leave code needs to first look for the mg in a
different list... once we get rid of the old code (post cluster3 split) we
can try again.