Re: + ext3-fix-online-resize-bug.patch added to -mm tree

[Andreas Dilger <adilger@sun.com>]

On Jun 02, 2008  17:22 -0700, Andrew Morton wrote:
> > ------------------------------------------------------
> > Subject: ext3: fix online resize bug
> > From: Josef Bacik <jbacik@redhat.com>
> > 
> > There is a bug when we are trying to verify that the reserve inode's
> > double indirect blocks point back to the primary gdt blocks.  The fix is
> > obvious, we need to mod the gdb count by the addr's per block.  You can
> > verify this with the following test case
> > 
> > dd if=/dev/zero of=disk1 seek=1024 count=1 bs=100M
> > losetup /dev/loop1 disk1
> > pvcreate /dev/loop1
> > vgcreate loopvg1 /dev/loop1
> > lvcreate -l 100%VG loopvg1 -n looplv1
> > mkfs.ext3 -J size=64 -b 1024 /dev/loopvg1/looplv1
> > mount /dev/loopvg1/looplv1 /mnt/loop
> > dd if=/dev/zero of=disk2 seek=1024 count=1 bs=50M
> > losetup /dev/loop2 disk2
> > pvcreate /dev/loop2
> > vgextend loopvg1 /dev/loop2
> > lvextend -l 100%VG /dev/loopvg1/looplv1
> > resize2fs /dev/loopvg1/looplv1
> > 
> > without this patch the resize2fs fails, with it the resize2fs succeeds.
> > 
> 
> Could I please gather some reviews and ackings on this?

You can add a Signed-off-by: Andreas Dilger <adilger@sun.com>
The wrapping is clearly correct, because the end of the res = 0 loop
is itself wrapping "data" after it exceeds "end".  The current code is
just broken if data >= end to start with.

> Also, do we think it is 2.6.25.x material?

It definitely contains no risk unless you are doing an online resize.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.