MIME-Version: 1.0
References: <a13cd3b5-cc41-bf2f-c8ac-e031ad0d5dd7@leemhuis.info>
 <CAPhsuW7ZWthh0PZt71hQh1_51C0yMSpOqWYJKc_+VzzTmW_r5A@mail.gmail.com> <167805126796.8008.3635368722810568057@noble.neil.brown.name>
In-Reply-To: <167805126796.8008.3635368722810568057@noble.neil.brown.name>
From:   Song Liu <song@kernel.org>
Date:   Mon, 6 Mar 2023 09:48:34 -0800
Message-ID: <CAPhsuW64R2ze1AYZhEmQcGf0cKBjjX=4EZZowD+=Cr=VPg1QYg@mail.gmail.com>
Subject: Re: [regression] Bug 217074 - upgrading to kernel 6.1.12 from 5.15.x
 can no longer assemble software raid0
To:     NeilBrown <neilb@suse.de>
Cc:     Linux regressions mailing list <regressions@lists.linux.dev>,
        Jes.Sorensen@gmail.com, linux-raid <linux-raid@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Nikolay Kichukov <hijacker@oldum.net>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Sun, Mar 5, 2023 at 1:21=E2=80=AFPM NeilBrown <neilb@suse.de> wrote:
>
> On Sat, 04 Mar 2023, Song Liu wrote:
> > + Jes.
> >
> > It appeared to me that we can assemble the array if we have any of the
> > following:
> > 1. Enable CONFIG_BLOCK_LEGACY_AUTOLOAD;
> > 2. Have a valid /etc/mdadm.conf;
> > 3. Update mdadm to handle this case. (I tried some ugly hacks, which wo=
rked but
> >     weren't clean).
> >
> > Since we eventually would like to get rid of CONFIG_BLOCK_LEGACY_AUTOLO=
AD, I
> > think we need mdadm to handle this properly. But the logistics might
> > be complicated, as
> > mdadm are shipped separately.
> >
> > Jes, what do you think about this? AFAICT, we need to update the logic =
in
> > mdopen.c:create_mddev().
>
> mdadm already handles this, but only if
>    CREATE names=3Dyes
> is present in /etc/mdadm.conf
>
> Maybe we should flip the default for the next mdadm release, and patch
> the kernel (with a stable backport) to select BLOCK_LEGACY_AUTOLOAD if
> BLK_DEV_MD=3Dm
> Then revert that - say - 6 months after the new mdadm is released.

I like this idea. I guess we also need to select BLOCK_LEGACY_AUTOLOAD
if BLK_DEV_MD=3Dy?

Thanks,
Song