I am till on the issue, the subject is way deeper than expected.
@frank-s Could you re-try the sequence and give us the error message please. You might have found a secondary issue with the error handler, it should have shown the message.
I have found a suspected O_DIRECT here, the solution won't come quickly.
@borzel I am struggling to match the error lines in your log with a source code, can you tell me what version of vhd-tool you have installed please ? (yum info vhd-tool)
yum info vhd-tool
@borzel good catch, it's another O_DIRECT issue.