Re: grub-probe detects ext4 wronly as ext2

[Robert Millan <rmh@aybabtu.com>]

On Mon, Jun 30, 2008 at 08:27:50PM +0800, Bean wrote:
> On Mon, Jun 30, 2008 at 8:12 PM, Javier Martín <lordhabbit@gmail.com> wrote:
> > El lun, 30-06-2008 a las 07:14 -0400, Isaac Dupree escribió:
> >> > +#define EXT3_FEATURE_INCOMPAT_RECOVER              0x0004 /* Needs recovery */
> >>
> >> > +#define EXT2_DRIVER_SUPPORTED_INCOMPAT ( EXT2_FEATURE_INCOMPAT_FILETYPE )
> >>
> >> I suspect this will mean that journalled ext3 when the system crashed
> >> (so the filesystem "needs recovery" from the journal) won't load.  (Of
> >> course, properly speaking that would load grub's code to replay the
> >> journal...)  But I think that (without other changes) that would make
> >> the system unbootable every time there was a power outage?  (Of course
> >> it was not guaranteed to load correctly when ignoring the journal when
> >> it needed recovery, but it was likely to work, IIUC.)
> >>
> >> -Isaac
> >
> > As I said, I didn't add it because I didn't know whether recovery was
> > supported or not. _Theoretically_ we should focus on correctness and
> > refuse to read such a filesystem, but here goes a workaround for
> > incompatible features that we do not support but still willingly want to
> > ignore for the sake of "compatibility". This new version of the patch
> > adds another macro, EXT2_DRIVER_IGNORED_INCOMPAT where we can put
> > features that we don't fully support, but still want a filesystem with
> > them to be mounted, like the needs_recover flag.
> >
> > Of course, this is risky: INCOMPAT_* features are so for a reason, but
> > it will allow dirty ext3 filesystems to be mounted until we have a
> > working journal implementation. I had thought of adding some kind of
> > warning, but since GRUB mounts and umounts filesystems constantly, it
> > just cluttered the screen and I removed it.
> 
> Hi,
> 
> We must not quit if the journal flag is set, even if we don't handle
> it. grub-setup runs in a active system, the journal wouldn't be empty.
> If we just quit, we can't even install.

I think we should be more conservative here, and only reject a filesystem
when we know _for sure_ that GRUB won't be able to access it.  Otherwise
we may be disabling filesystems that are probably fine.

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)