qcow2 corruption - seems to be fixed in kvm-85 and later :-)

[Jamie Lokier <jamie@shareable.org>]

Hi,

Sometimes it's nice to find a mail with good news.

A while back I reported corruption with qcow2, with the subject
"qcow2 corruption observed, fixed by reverting old change".

I'd noticed that kvm-83 was corrupting a Windows 2k disk image, which
was failing to boot, blue screening quite early.

I found there was a qcow2 bug introduced from kvm-72 to kvm-73, and
another from kvm-76 to kvm-77.  Reverting both fixed this symptom.


In order to check the bug later, I kept a copy of the disk image which
blue screened.

It still crashes with kvm-84.  The release notes indicate there were
some qcow2 fixes in that version; they were not enough to fix this
problem.

There were more qcow2 fixes in kvm-85.

Happily, I can now report that kvm-85 and kvm-88 both boot this image
with no apparent problems, and I will be deleting this junk disk image
now that I'm confident no further testing is required :-)


Thanks!
-- Jamie