Re: [PATCH 0/6] multipath-tools: Handle tableless DM devices

[Benjamin Marzinski <bmarzins@redhat.com>]

On Mon, Nov 18, 2024 at 12:18:20PM +0100, Martin Wilck wrote:
> On Fri, 2024-11-15 at 18:22 -0500, Benjamin Marzinski wrote:
> > 
> > I'm not completely happy with the MAPINFO_ID_IF_FOUND flag. An
> > alternative would be to run a second libmp_mapinfo() call without
> > MAPINFO_MPATH_ONLY to grab the name, if the first failed with
> > DMP_EMPTY.
> > If people think that's a better way to solve this, I can rework those
> > patches.
> 
> We could simply choose to always fill in this information if the
> the caller has requested it, without an additional input flag. It's not
> an expensive operation. Is there a reason not to do this?

Your comments in the code said that libmp_mapinfo() will not touch any
of the output parameters if it doesn't succeed. I didn't audit the code,
but I can certainly imagine a situation where you passed in pointers to
some varaibles that already had values and you didn't want those values
overwritten unless libmp_mapinfo() returned DMP_OK.

But I can go look and see if any callers would get messed up if name or
uuid got set, even when the found device didn't match.

-Ben

> 
> Thanks
> Martin