Re: [regression] Bug 217074 - upgrading to kernel 6.1.12 from 5.15.x can no longer assemble software raid0

[Song Liu]

On Sun, Mar 5, 2023 at 1:21 PM NeilBrown <neilb@xxxxxxx> 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 worked but
> >     weren't clean).
> >
> > Since we eventually would like to get rid of CONFIG_BLOCK_LEGACY_AUTOLOAD, 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=yes
> 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=m
> 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=y?

Thanks,
Song