On Wed, Jul 09, 2014 at 02:38:19PM -0600, Andreas Dilger wrote: > > On Jul 8, 2014, at 2:41 PM, Azat Khuzhin <a3at.mail@xxxxxxxxx> wrote: > > > Using -U option you can change the UUID for fs, however it will not work > > for journal device, since it have a copy of this UUID inside jsb (i.e. > > journal super block). So copy UUID on change into that block. > > > > Here is the initial thread: > > http://comments.gmane.org/gmane.comp.file-systems.ext4/44532 > > > > You can reproduce this by executing following commands: > > $ fallocate -l100M /tmp/dev > > $ fallocate -l100M /tmp/journal > > $ sudo /sbin/losetup /dev/loop1 /tmp/dev > > $ sudo /sbin/losetup /dev/loop0 /tmp/journal > > $ mke2fs -O journal_dev /tmp/journal > > $ tune2fs -U da1f2ed0-60f6-aaaa-92fd-738701418523 /tmp/journal > > $ sudo mke2fs -t ext4 -J device=/dev/loop0 /dev/loop1 > > $ dumpe2fs -h /tmp/dev | fgrep UUID > > dumpe2fs 1.43-WIP (18-May-2014) > > Filesystem UUID: 8a776be9-12eb-411f-8e88-b873575ecfb6 > > Journal UUID: e3d02151-e776-4865-af25-aecb7291e8e5 > > $ sudo e2fsck /dev/vdc > > e2fsck 1.43-WIP (18-May-2014) > > External journal does not support this filesystem > > > > /dev/loop1: ********** WARNING: Filesystem still has errors ********** > > > > Reported-by: Chin Tzung Cheng <chintzung@xxxxxxxxx> > > Signed-off-by: Azat Khuzhin <a3at.mail@xxxxxxxxx> > > It may be that the reverse problem also exists - if the UUID is changed > on the filesystem, it probably is not updated in the journal "users" list? > I'm not sure either way, but it is worthwhile to check. You are right, it will not update the 'Journal users' field, there is no code for U_flag in tune2fs for this (I also test it). But to make patch clean I need more time, I will send it later. > > Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx> Thanks! -- Respectfully Azat Khuzhin -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
