Re: [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening

[Daniel P. Berrange]

On Tue, May 10, 2016 at 01:11:30PM +0100, Richard W.M. Jones wrote:
> At no point did I say that it was safe to use libguestfs on live VMs
> or that you would always get consistent data out.
> 
> But the fact that it can fail is understood, the chance of failure is
> really tiny (it has literally only happened twice that I've read
> corrupted data, in years of daily use), and the operation is very
> useful.
> 
> So I think this patch series should either not lock r/o VMs, or should
> add a nolock flag to override the locking (which libguestfs will
> always use).

If QEMU locks r/o disks, then libvirt would likely end up setting the
"nolock" flag unconditionally too, in order to avoid breaking libguestfs
and other application usage of libvirt.

Regards,
Daniel
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