Re: ext4 error when testing virtio-scsi & vhost-scsi

Dave Chinner
2016-07-12T23:03:56Z

On Tue, Jul 12, 2016 at 12:43:24PM -0400, Theodore Ts'o wrote:
> On Tue, Jul 12, 2016 at 03:14:38PM +0800, Zhangfei Gao wrote:
> > Some update:
> >
> > If test with ext2, no problem in iblock.
> > If test with ext4, ext4_mb_generate_buddy reported error in the
> > removing files after reboot.
> >
> >
> > root@(none)$ rm test
> > [ 21.006549] EXT4-fs error (device sda): ext4_mb_generate_buddy:758: group 18
> > , block bitmap and bg descriptor inconsistent: 26464 vs 25600 free clusters
> > [ 21.008249] JBD2: Spotted dirty metadata buffer (dev = sda, blocknr = 0). Th
> > ere's a risk of filesystem corruption in case of system crash.
> >
> > Any special notes of using ext4 in qemu?
>
> Ext4 has more runtime consistency checking than ext2. So just because
> ext4 complains doesn't mean that there isn't a problem with the file
> system; it just means that ext4 is more likely to notice before you
> lose user data.
>
> So if you test with ext2, try running e2fsck afterwards, to make sure
> the file system is consistent.
>
> Given that I'm reguarly testing ext4 using kvm, and I haven't seen
> anything like this in a very long time, I suspect the problemb is with
> your SCSI code, and not with ext4.

It's the same error I reported yesterday for ext3 on 4.7-rc6 when
rebooting a VM after it hung.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com