Re: [Qemu-devel] qcow2 corruption observed, fixed by reverting old change

[Kevin Wolf <kwolf@suse.de>]

Jamie Lokier schrieb:
> Kevin Wolf wrote:
>> Besides reviewing the code over and over again, I think the only real
>> chance is that you can get a non-productive copy of your image and add
>> some debug code so that we can see at least which code path is causing
>> problems.
> 
> I have a copy of my image to reproduce the bug, so I can test patches
> including diagnostic patches.  That's what I did to narrow it down.
> 
> Being a company mail server, I can't send you the image of course.

I perfectly understand that, it just makes debugging hard when you don't
have a specific suspicion nor the problematic image.

Do you need those diagnostic patches from me or will you try to put
debug messages into the code yourself? I would just start putting in
random printfs into alloc_cluster_offset() and the functions it calls to
get some information about the failing write. I guess we'd need some
iterations with my diagnostic patch and it wouldn't be any better than
ad-hoc hacks done by yourself.

>> By the way and completely off-topic: Have you already tried to use the
>> VHD patches? I would really like to know if they fix your problems.
> 
> Are those patches in kvm-83?  I still have the image that was causing
> problems way back, and I'm converting it to raw now with kvm-83 to see
> if it now matches the raw image produced by VPC's own tool.

Avi mentioned the patches in the kvm-84 announcement yesterday, so it
seems they are not in kvm-83.

Kevin