Re: Worse yet Re: Whoops! Re: [PATCH] Another semi-critical one... (was Re: towards 0.91 )

[Yoshinori K. Okuji]

At Tue, 06 Nov 2001 17:02:03 -0800,
address@hidden wrote:
> Though, I'm pretty sure ext3 and XFS at least have decided this by that
> time, since they only journal metadata.  I'm not sure about JFS or
> ReiserFS.

If my understanding is correct, ReiserFS only journals metadata,
too. I don't know much about JFS.

However, if all the journaling filesystems don't journal the contents
of files, as Jochen pointed out, wouldn't it be enough for us to
add support for reading journals of XFS and JFS into GRUB? I see no
reason why we need to flush journals, once GRUB has real support for
journaling filesystems, like ReiserFS.

> This may be the best thing.  Maybe I should just go figure this out
> to ease my mind on what's going on with LILO and block-maps on the other
> journaled FSes too.

I took a look at the lastest version of LILO, and I understood that it
didn't do anything special but the REISERFS_IOC_UNPACK ioctl. Anyway,
LILO just uses the kernel service, FIBMAP, so I guess the kernel can
ensure that bmaps are complete, even if a journaling filesystem
journals every data.

> I originally intended the GRUB "install" command to be run at boot-time
> because that was really the only safe time/OS-independent way I could
> see to do it.  The creation/use of the GRUB shell is clever, but not
> guaranteed to be safe.

That's right. Of course. So I wrote in the manual, "Using the native
environment is definitely better! Using the grub shell is dangerous!",
etc. However, I want to say, it should be possible to make the
GRUB installation on a running system as robust and reliable as that
on a bare system, in most situations. We should always warn the
danger, but I don't want to stop improving it.

BTW, I think the REISERFS_IOC_UNPACK ioctl would be a Good Thing to
have, as GRUB requires to be aligned. Any volunteer?

Okuji