RE: patch to discovery.c to still get pathpriorityforpaths with path state of PATH_DOWN

[Dave Wysochanski <dave.wysochanski@redhat.com>]

On Wed, 2006-11-15 at 14:48 -0500, Edward Goggin wrote:
> On Wednesday, November 15, 2006 1:49 AM, Dave Wysochanski wrote
> 
> > One other thought I had was the notion of a "priority valid" 
> > flag (or a
> > special priority value) in the path for the case of 
> > group_by_prio.  Set
> > it to invalid in alloc_path(), then just don't add the path to the
> > multipath struct in coalesce_paths() if the priority value 
> > was invalid.
> > Then over in checkerloop(), add the path to the multipath map when you
> > get a valid priority.
> > 
> > It is more complicated than that I'm sure (e.g. checkerloop() assumes
> > pp->mpp is non-null in places, etc) but seemed like a half-decent
> > approach to at least consider.
> > 
> > This approach doesn't take into consideration the general case of a
> > change in path priority though.
> 
> I very much like the first part of your "priority valid" idea
> mentioned above.
> 
> I've enclosed a patch for the first part of your idea.  The patch
> should address the concern you had about recalculating priority
> for a path when its path state changes from not PATH_DOWN to
> PATH_DOWN.  It now only retrieves the priority for PATH_DOWN
> paths if the path's priority has never been successfully
> retrieved before.
> 
Great.  Your patch looks fine.

> I've punted for now on the reloading of the map if a path priority
> change has caused a path group membership change.  This is kind of
> complex, has lots of down sides, and there doesn't seem to be a
> need for it as of now.

Sure that's fine.  That would be extreme and I'm all for simplicity.