[libvirt] qemu_migration: Precreate missing storage breaks with network drives

Noel Burton-Krahn noel at pistoncloud.com
Fri Mar 20 19:23:22 UTC 2015


Hi Michal,

I think issuing a libvirt migrate to a host where the network disks don't
already exist would be a prequisite failure.  Libvirt can never copy a
network disk, but it shouldn't fail trying to migrate an existing domain
that contains a network disk.  If a libvirt user wishes to migrate a domain
that contains a network disk, it's their responsibility to ensure the disk
exists before calling migrate.

Could you propose this patch to libvirt?

--
Noel





On Thu, Mar 19, 2015 at 3:45 AM, Michal Privoznik <mprivozn at redhat.com>
wrote:

> On 18.03.2015 22:00, Nick Bartos wrote:
> > Actually I messed that up slightly on the case.  My C is a bit rusty:
> >
> > diff -U3 -r libvirt-1.2.13.orig/src/qemu/qemu_migration.c
> > libvirt-1.2.13/src/qemu/qemu_migration.c
> > --- libvirt-1.2.13.orig/src/qemu/qemu_migration.c2015-02-23
> > 22:04:12.000000000 -0800
> > +++ libvirt-1.2.13/src/qemu/qemu_migration.c2015-03-18
> > 13:55:45.873322477 -0700
> > @@ -1507,9 +1507,12 @@
> >              flags |= VIR_STORAGE_VOL_CREATE_PREALLOC_METADATA;
> >          break;
> >
> > +    case VIR_STORAGE_TYPE_NETWORK:
> > +        ret = 0;
> > +        goto cleanup;
> > +        break;
> >      case VIR_STORAGE_TYPE_BLOCK:
> >      case VIR_STORAGE_TYPE_DIR:
> > -    case VIR_STORAGE_TYPE_NETWORK:
> >      case VIR_STORAGE_TYPE_NONE:
> >      case VIR_STORAGE_TYPE_LAST:
> >          virReportError(VIR_ERR_INTERNAL_ERROR,
>
> Sounds reasonable to me. Although I'm worried that there might be users
> using network disk, supplying different XML on migration, where the disk
> is switched to yet non-existent network disk, expecting libvirt/qemu to
> copy the data.
>
> The other option is: libvirt won't copy shared or read only disks. So
> OpenStack would mark network disks as shared.
>
> One way or another - do you want to propose a patch or should I do that?
>
> Michal
>
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