[dm-devel] patch to discovery.c to still getpathpriorityforpaths with path state of PATH_DOWN

[Edward Goggin]

OK.  I was trying not to have to introduce another
prio state because that approach just seems prone
to error.

I'll give it a try tomorrow.

> -----Original Message-----
> From: Christophe Varoqui [mailto:christophe.varoqui at free.fr] 
> Sent: Wednesday, November 15, 2006 5:34 PM
> To: goggin, edward
> Cc: dave.wysochanski at redhat.com; dm-devel at redhat.com
> Subject: RE: [dm-devel] patch to discovery.c to still 
> getpathpriorityforpaths with path state of PATH_DOWN
> 
> Le mercredi 15 novembre 2006 à 14:48 -0500, Edward Goggin a écrit :
> > 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.
> > 
> How about the following, clarifying PRIO values and avoiding the
> additional "struct path" element ?
> 
> Please have a careful look at the 
> multipath/main.c:update_paths change,
> because the (!pp->priority) that was there awfully looks like 
> a bug (as
> 0 is not a defined prio value).
> 
> Regards,
> cvaroqui
> 
> 
>