[dm-devel] [RFC PATCH v2 3/3] libmultipath: change log level for null uid_attribute

[Benjamin Marzinski]

On Thu, Sep 24, 2020 at 08:06:41AM +0000, Martin Wilck wrote:
> On Wed, 2020-09-23 at 23:59 -0500, Benjamin Marzinski wrote:
> > If uid_attribute is explicitly set to an empty string, multipath
> > should
> > log the uid at the default log level, since using the fallback code
> > is
> > the expected behavior.
> > 
> > Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> > ---
> >  libmultipath/discovery.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> > index f650534f..435f2639 100644
> > --- a/libmultipath/discovery.c
> > +++ b/libmultipath/discovery.c
> > @@ -2091,7 +2091,8 @@ get_uid (struct path * pp, int path_state,
> > struct udev_device *udev,
> >  		}
> >  		if ((!udev_available || (len <= 0 && allow_fallback))
> >  		    && has_uid_fallback(pp)) {
> > -			used_fallback = 1;
> > +			if (udev_available || !(udev && pp-
> > >uid_attribute))
> > +				used_fallback = 1;
> >  			len = uid_fallback(pp, path_state, &origin);
> >  		}
> >  	}
> 
> Uff, this logic was convoluted anyway, now it's even harder to grasp.
> IIUC, if !udev, used_fallback will be set to 1, even if 
> pp->uid_attribute is the empty string. Is that intended?
> To make this easier to read, I'd suggest something like this:

My though was that not having a udev device is an unexpected situation,
and so we should continue to log the message at an increased logging
level.  If you're against that, it's not that important. I can certainly
go with your code logic, or "if (!udev || !empty_uid_attr)" if you think
it's reasonable to log at an increased level whenever the udev_device is
NULL, even if the device was configured to ignore the udev database.

-Ben

> 
> 		bool valid_uid_attr = pp->uid_attribute
> 			&& *pp->uid_attribute;
> 		bool empty_uid_attr = pp->uid_attribute
> 			&& !*pp->uid_attribute;
> 		bool udev_available = udev && valid_uid_attr;
>       ...
> 		if ((!udev_available || (len <= 0 && allow_fallback))
> 		    && has_uid_fallback(pp)) {
> 			if (!empty_uid_attr)
> 				used_fallback = 1;
> 			len = uid_fallback(pp, path_state, &origin);
> 
> Regards,
> Martin
> 
> -- 
> Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
> SUSE  Software Solutions Germany GmbH
> HRB 36809, AG Nürnberg GF: Felix
> Imendörffer
>