[dm-devel] [PATCH 4/4] libmultipath: fix mpcontext initialization

[Benjamin Marzinski]

On Fri, Sep 13, 2019 at 08:28:59AM +0000, Martin Wilck wrote:
> On Tue, 2019-09-10 at 17:39 -0500, Benjamin Marzinski wrote:
> > If a path is discovered before there is a multipath device for it to
> > belong to, the checker will not have its mpcontext initialized, even
> > if
> > that path later belongs to a multipath device. A checker's mpcontext
> > is
> > only set when the checker is selected, and is set to NULL if there is
> > no
> > multipath device associated with the path. This only impacts the emc
> > checker. However, it makes the emc checker unable to determine if a
> > passive path is connected to an inactive snapshot or not.
> > 
> > This can be solved by adding a new checker class function, mp_init().
> > This is called when the checker is first initialized, and whenever
> > the
> > checker is called, if the checker's mpcontext hasn't been
> > initialized.
> > 
> > Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> > ---
> >  libmultipath/checkers.c              | 29
> > ++++++++++++++++++++++++++--
> >  libmultipath/checkers.h              |  1 +
> >  libmultipath/checkers/cciss_tur.c    |  5 +++++
> >  libmultipath/checkers/directio.c     |  5 +++++
> >  libmultipath/checkers/emc_clariion.c |  7 +++++++
> >  libmultipath/checkers/hp_sw.c        |  5 +++++
> >  libmultipath/checkers/rdac.c         |  5 +++++
> >  libmultipath/checkers/readsector0.c  |  5 +++++
> >  libmultipath/checkers/tur.c          |  5 +++++
> >  libmultipath/discovery.c             |  2 ++
> >  10 files changed, 67 insertions(+), 2 deletions(-)
> > 
> 
> I see the problem and agree the solution is correct. But I'd prefer if
> the mp_init() method was optional and, if not defined in the
> libcheckX.so, would simply be set to NULL. So you wouldn't need to
> define empty methods for all checkers except emc. 

Sure.

-Ben

> checker_mp_init() checks for mp_init() being non-NULL anyway.
> 
> Thanks,
> Martin
>