Re: [PATCH v2 5/7] qemu: Block migration when transient disk option is enabled

[Masayoshi Mizuma <msys.mizuma@xxxxxxxxx>]

On Tue, Sep 08, 2020 at 03:17:47PM +0200, Peter Krempa wrote:
> On Fri, Aug 28, 2020 at 10:08:35 -0400, Masayoshi Mizuma wrote:
> > From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
> > 
> > Block migration when transient disk option is enabled because migration
> > requires some blockjobs.
> > 
> > Signed-off-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
> > ---
> >  src/qemu/qemu_migration.c | 22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> > 
> > diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> > index 0f2f92b211..6fcf5a3a07 100644
> > --- a/src/qemu/qemu_migration.c
> > +++ b/src/qemu/qemu_migration.c
> > @@ -2949,6 +2949,22 @@ qemuMigrationDstPrepareDirect(virQEMUDriverPtr driver,
> >  }
> >  
> >  
> > +static bool
> > +qemuMigrationTransientDiskExists(virDomainDefPtr def)
> > +{
> > +    size_t i;
> > +
> > +    for (i = 0; i < def->ndisks; i++) {
> > +       virDomainDiskDefPtr disk = def->disks[i];
> > +
> > +       if (disk->transient)
> > +            return true;
> > +    }
> > +
> > +    return false;
> > +}
> > +
> > +
> >  virDomainDefPtr
> >  qemuMigrationAnyPrepareDef(virQEMUDriverPtr driver,
> >                             virQEMUCapsPtr qemuCaps,
> > @@ -2971,6 +2987,12 @@ qemuMigrationAnyPrepareDef(virQEMUDriverPtr driver,
> >                                          VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE)))
> >          goto cleanup;
> >  
> > +    /*
> > +     * transient disk option is a blocker for migration
> > +     */
> > +    if (qemuMigrationTransientDiskExists(def))
> > +       goto cleanup;
> 
> This should really be placed into qemuMigrationSrcIsAllowed() rather
> than open-coded. Migration is used in other places too and doesn't use
> this API to trigger it.

OK, I'll add the following to block the migration.

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index a530c17582..7316d74677 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1397,6 +1397,16 @@ qemuMigrationSrcIsAllowed(virQEMUDriverPtr driver,
                            _("cannot migrate this domain without dbus-vmstate support"));
             return false;
         }
+
+        for (i = 0; i < vm->def->ndisks; i++) {
+            virDomainDiskDefPtr disk = vm->def->disks[i];
+
+            if (disk->transient) {
+                virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+                           _("migration with transient disk is not supported"));
+                return false;
+            }
+        }
     }
 
     return true;