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Re: Converting root ext3 to ext2?

On Thu, 3 Oct 2002, Michael J. Accetta wrote:

> Can anyone comment on whether or not it is possible to successfully
> disable the journal of an ext3 root file system prior to reboot?

No.  The kernel will still be aware of the journal until the filesystem is

> My application is to try and make sure there is no journal prior to
> installing and rebooting into a system which does not support ext3.
> I know that as long as the root is cleanly remounted r/o with no
> journal updates pending, this will be compatible.  I'm trying to also
> cover the case where something goes wrong during the subsequent
> install and we reboot into a system without ext3 support but where the
> root file system did not get unmounted properly first.  Using
>     tune2fs -O ^has_journal /dev/xxx
> on a r/o ext3 root appears to succeed but I later see file system
> corruption after remounting r/w to install the non-ext2 system files
> and  suspect that the kernel still has it fingers on some old journal
> resources after the r/w remount following removal of the journal.

You need to reboot after running the tune2fs command, so that the kernel
mounts the fs as ext2.  You cannot change filesystem types with a remount.
Also, I think the journal inode will not be deleted until you run e2fsck,
after removing the has_journal feature and rebooting.  The linux kernel
will be fine, but I belive both Norton Ghost and PartitonMagic will choke
and potentially corrupt your filesystem if you run them while the journal
inode still exists.

      -Matt Stegman

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