On Wed, Jul 20, 2022 at 4:01 PM Jiri Denemark <jdenemar@xxxxxxxxxx> wrote:
>
> On Wed, Jul 20, 2022 at 14:15:57 +0200, Eugenio Pérez wrote:
> > since qemu 6.0, if migration is blocked for some reason, 'query-migrate'
> > will return an array of error strings describing the migration blockers.
> > This can be used to check whether there are any devices blocking
> > migration, etc.
> >
> > Enable qemuMigrationSrcIsAllowed to query it.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
> > ---
> > v3:
> > * Report message with a colon.
> > * Report all blockers instead of only the first.
> > ---
> > src/qemu/qemu_migration.c | 34 ++++++++++++++++++++++++++++++++++
> > 1 file changed, 34 insertions(+)
> >
> > diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> > index b12cb518ee..6ac4ef150b 100644
> > --- a/src/qemu/qemu_migration.c
> > +++ b/src/qemu/qemu_migration.c
> > @@ -1414,6 +1414,20 @@ qemuMigrationSrcIsAllowedHostdev(const virDomainDef *def)
> > return true;
> > }
> >
> > +static int
> > +qemuDomainGetMigrationBlockers(virQEMUDriver *driver,
> > + virDomainObj *vm,
> > + char ***blockers)
> > +{
> > + qemuDomainObjPrivate *priv = vm->privateData;
> > + int rc;
> > +
> > + qemuDomainObjEnterMonitor(driver, vm);
> > + rc = qemuMonitorGetMigrationBlockers(priv->mon, blockers);
> > + qemuDomainObjExitMonitor(vm);
> > +
> > + return rc;
> > +}
> >
> > /**
> > * qemuMigrationSrcIsAllowed:
> > @@ -1439,6 +1453,26 @@ qemuMigrationSrcIsAllowed(virQEMUDriver *driver,
> > int nsnapshots;
> > int pauseReason;
> > size_t i;
> > + int r;
> > +
> > + /* Ask qemu if it have a migration blocker */
> > + if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MIGRATION_BLOCKED_REASONS)) {
> > + g_auto(GStrv) blockers = NULL;
> > + r = qemuDomainGetMigrationBlockers(driver, vm, &blockers);
> > + if (r != 0) {
> > + virReportError(VIR_ERR_OPERATION_INVALID,
> > + _("cannot migrate domain: %s"),
> > + _("error getting blockers"));
> > + return false;
> > + }
>
> As mentioned in v2 review the virReportError call should be dropped as
> it overwrites the error reported by qemuDomainGetMigrationBlockers. That
> is, you can just
>
> if (qemuDomainGetMigrationBlockers(driver, vm, &blockers) < 0)
> return false;
>
But there are a few conditions that don't report an error, like a bad
JSON answer. For example, if "blockers" is not an array parsing the
response JSON, libvirt would not print any error, isn't it?
> > +
> > + if (blockers && blockers[0]) {
> > + g_autofree char *reasons = g_strjoinv(", ", blockers);
>
> In the following patch you change ", " to "; ". I don't mind that much
> either way, but it should be done in this patch :-)
>
> > + virReportError(VIR_ERR_OPERATION_INVALID,
> > + _("cannot migrate domain: %s"), reasons);
> > + return false;
> > + }
> > + }
> >
> > /* perform these checks only when migrating to remote hosts */
> > if (remote) {
>
> Hmm, easy but not trivial changes so I guess v4 would be better.
>
> Jirka
>
