Re: [PATCH - mdadm] mdopen: always try create_named_array()

["NeilBrown" <neilb@suse.de>]

On Thu, 30 Mar 2023, Xiao Ni wrote:
> On Thu, Mar 30, 2023 at 5:52 AM NeilBrown <neilb@suse.de> wrote:
> >
> > On Wed, 22 Mar 2023, NeilBrown wrote:
> > > On Wed, 22 Mar 2023, Xiao Ni wrote:
> > >
> > > >
> > > > Second, are there possibilities that the arguments "dev" and "name" of
> > > > function create_mddev
> > > > are null at the same time?
> > >
> > > No.  For Build or Create, dev is never NULL.  For Assemble and
> > > Incremental, name is never NULL.
> > >
> >
> > I should clarify this a bit.  For Assemble and Incremental, "name" is
> > never NULL *but* it might be an empty string.
> > So:
> >         if (name && name[0] == 0)
> >                 name = NULL;
> >
> > might cause it to become NULL.  So you cannot assume there is always
> > either a valid "dev" or a valid "name".  "dev" might be NULL, and "name"
> > might be "".
> >
> > NeilBrown
> >
> 
> Hi Neil
> 
> The input argument name should be the metadata name. For incremental
> and assemble, why are there possibilities that the metadata name is
> invalid? A raid device should have a valid metadata name, right?

"should" do, yes.  But you can never completely trust data on disk.  It
is safest to be prepared for "name" being "".

NeilBrown