[libvirt] [PATCH 01/23] qemu: driver: Don't call qemuDomainDetermineDiskChain on block jobs

[Peter Krempa]

On Thu, Mar 23, 2017 at 10:31:06 -0500, Eric Blake wrote:
> On 03/23/2017 02:13 AM, Peter Krempa wrote:
> > On Wed, Mar 22, 2017 at 14:21:29 -0500, Eric Blake wrote:
> >> On 03/15/2017 11:37 AM, Peter Krempa wrote:
> >>> Our code calls it when starting or re-starting the domain or when
> >>> hotplugging the disk so there's nothing to be detected.
> >>> ---
> >>>  src/qemu/qemu_driver.c | 5 -----
> >>>  1 file changed, 5 deletions(-)
> >>>
> >>
> >> I think I added it here because block jobs have the tendency to rewrite
> >> the backing chain (think active commit, for example, which reduces the
> >> backing chain).  Forcing a redetermination is therefore a way to ensure
> >> no stale data associated with the pre-job chain is left in memory.
> >>
> >> So I'm not sure this is correct.
> > 
> > We re-detect the backing chain when the VM is started, when we reconnect
> > to it and when we get any of the blockjob-related events.
> 
> Do we still care about qemu old enough where events did not appear, and
> therefore where we had to fake events ourselves when we detect that the
> job is complete? If so, then we want to redetect the chain (but only for
> those older qemu); if not, then I can agree to your cleanup because
> redetection at the event is sufficient.

Since nobody complained that it would not work properly with such old
qemus I don't think that anybody uses it.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20170323/019e1683/attachment-0001.sig>