conf: Validate disk lun using correct types

https://bugzilla.redhat.com/show_bug.cgi?id=1201143

The formatdomain.html description for <disk> device 'lun' indicates that
it must be either a type 'block' or type 'network' with protocol 'iscsi';
however, we did not make that check until domain startup.

This caused issues for virt-manager which had an unexpected failure at
run time rather config time.

This patch adds a check in post part disk device checking for the specific
and supported lun types as well as adjusting the test failure to be for
parse config rather than run time.

src/conf/domain_conf.c

@@ -3893,6 +3893,28 @@ virDomainDeviceDefPostParseInternal(virDomainDeviceDefPtr dev,
                 return -1;
             }
         }
+
+        /* Validate LUN configuration
+         * NOTE: virStorageTranslateDiskSourcePool is not run yet, so for
+         *       disk "volume"'s, the closest we can get at config time is
+         *       to ensure mode isn't direct since host/default will allow
+         *       lun/block usage. At run time if it's determined the wrong
+         *       voltype and pooltype values are set, then failure occurs
+         */
+        if (disk->device == VIR_DOMAIN_DISK_DEVICE_LUN &&
+            !(disk->src->type == VIR_STORAGE_TYPE_BLOCK ||
+              (disk->src->type == VIR_STORAGE_TYPE_NETWORK &&
+               disk->src->protocol == VIR_STORAGE_NET_PROTOCOL_ISCSI) ||
+              (disk->src->type == VIR_STORAGE_TYPE_VOLUME &&
+               disk->src->srcpool &&
+               disk->src->srcpool->mode !=
+               VIR_STORAGE_SOURCE_POOL_MODE_DIRECT))) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("disk '%s' improperly configured for a "
+                             "device='lun'"),
+                           disk->dst);
+            return -1;
+        }
     }
 
     if (dev->type == VIR_DOMAIN_DEVICE_VIDEO) {

tests/qemuxml2argvtest.c

@@ -818,7 +818,7 @@ mymain(void)
                     QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
     DO_TEST("disk-drive-no-boot",
             QEMU_CAPS_DRIVE, QEMU_CAPS_DEVICE, QEMU_CAPS_BOOTINDEX);
-    DO_TEST_FAILURE("disk-device-lun-type-invalid",
+    DO_TEST_PARSE_ERROR("disk-device-lun-type-invalid",
                     QEMU_CAPS_DRIVE, QEMU_CAPS_DEVICE, QEMU_CAPS_VIRTIO_SCSI);
     DO_TEST("disk-usb",  NONE);
     DO_TEST("disk-usb-device",