libvirt users - Jan 2020 - Re: Locking without virtlockd (nor sanlock)?

Il 06-01-2020 10:06 Peter Krempa ha scritto:
> On Fri, Jan 03, 2020 at 14:08:03 +0000, Daniel Berrange wrote:
>> As above, QEMU's locking is good enough to rely on for file based
>> images.
Hi Daniel, thank you for the direct confirmation.
>> The flaws I mention with libvirt might actually finally be something 
>> we
>> have fixed in 5.10.0 with QEMU 4.2.0, since we can finally use 
>> "blockdev"
>> syntax for configuring disks.  Copying Peter to confirm/deny this...
> 
> The main issue was that we were leaking locks on the backing chain. 
> This
> should be now fixed with -blockdev as we call the appropriate apis to
> lock/unlock the images but I didn't try it with virtlockd.
> 
> Certainly if there's still a problem now we have well defined places
> where we know what's happening to images so it should be easy to fix
> them.
Hi Peter, can I ask what do you mean with "fixed with -blockdev"?

Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8

On Mon, Jan 06, 2020 at 18:44:31 +0100, Gionatan Danti
wrote:
> Il 06-01-2020 10:06 Peter Krempa ha scritto:
> > On Fri, Jan 03, 2020 at 14:08:03 +0000, Daniel Berrange wrote:
> > > As above, QEMU's locking is good enough to rely on for file
based
> > > images.
> 
> Hi Daniel, thank you for the direct confirmation.
> 
> > > The flaws I mention with libvirt might actually finally be
something
> > > we
> > > have fixed in 5.10.0 with QEMU 4.2.0, since we can finally use
> > > "blockdev"
> > > syntax for configuring disks.  Copying Peter to confirm/deny
this...
> > 
> > The main issue was that we were leaking locks on the backing chain.
This
> > should be now fixed with -blockdev as we call the appropriate apis to
> > lock/unlock the images but I didn't try it with virtlockd.
> > 
> > Certainly if there's still a problem now we have well defined
places
> > where we know what's happening to images so it should be easy to
fix
> > them.
> 
> Hi Peter, can I ask what do you mean with "fixed with -blockdev"?
blockdev is the new way to specify disks on qemu command line. It
required quite a lot of internal changes, some of which probably fixed
the block job cooperation with virtlockd. (leaking locks of images).

Blockdev is used starting from libvirt-5.10 and qemu-4.2

Il 07-01-2020 08:31 Peter Krempa ha scritto:
> blockdev is the new way to specify disks on qemu command line. It
> required quite a lot of internal changes, some of which probably fixed
> the block job cooperation with virtlockd. (leaking locks of images).
> 
> Blockdev is used starting from libvirt-5.10 and qemu-4.2
Understood. Thank you so much.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8