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

From: Xiao Ni <xni@redhat.com>
To: NeilBrown <neilb@suse.de>
Cc: Jes Sorensen <jes@trained-monkey.org>,
	 Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>,
	Song Liu <song@kernel.org>,
	 Linux regressions mailing list <regressions@lists.linux.dev>,
	linux-raid <linux-raid@vger.kernel.org>,
	 LKML <linux-kernel@vger.kernel.org>,
	Nikolay Kichukov <hijacker@oldum.net>
Subject: Re: [PATCH - mdadm] mdopen: always try create_named_array()
Date: Thu, 30 Mar 2023 08:10:45 +0800	[thread overview]
Message-ID: <CALTww28X1NQecTY3Jbkz_wbHc_N7GOw3hJLEyb2YnxAmQ8PRFw@mail.gmail.com> (raw)
In-Reply-To: <168012671413.8106.6812573281942242445@noble.neil.brown.name>

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?

-- 
Best Regards
Xiao Ni