qemuMigrationSrcRun: Don't attempt any storage migration if no disks will be migrated

Don't even try to setup storage migration if there are no eligible
disks.

This also fixes migration from older libvirts which didn't format an
empty <nbd/> element in the migration cookie if there weren't any disks
to migrate.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Tested-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 9ea008836c4f7658db6f07e72f506ad66c1c8b85..119459342e1dcf974b5305a9d70a8c4ac42defad 100644 (file)
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -312,6 +312,22 @@ qemuMigrationAnyCopyDisk(virDomainDiskDef const *disk,
 }
 
 
+static bool
+qemuMigrationHasAnyStorageMigrationDisks(virDomainDef *def,
+                                         const char **migrate_disks,
+                                         size_t nmigrate_disks)
+{
+    size_t i;
+
+    for (i = 0; i < def->ndisks; i++) {
+        if (qemuMigrationAnyCopyDisk(def->disks[i], nmigrate_disks, migrate_disks))
+            return true;
+    }
+
+    return false;
+}
+
+
 static int
 qemuMigrationDstPrecreateStorage(virDomainObj *vm,
                                  qemuMigrationCookieNBD *nbd,
@@ -4011,6 +4027,11 @@ qemuMigrationSrcRun(virQEMUDriver *driver,
               spec, spec->destType, spec->fwdType, dconn,
               NULLSTR(graphicsuri), nmigrate_disks, migrate_disks);
 
+    if (storageMigration)
+        storageMigration = qemuMigrationHasAnyStorageMigrationDisks(vm->def,
+                                                                    migrate_disks,
+                                                                    nmigrate_disks);
+
     if (storageMigration) {
         cookieFlags |= QEMU_MIGRATION_COOKIE_NBD;