[libvirt] [PATCHv2] qemu: fix unsuitable error report when get memory stats

[Wang Yufei]

From: Zhang Bo <oscar.zhangbo at huawei.com>

when we run the command 'virsh dommemstat xxx',
althrough memballoon's model is set 'none' in vm's XML,
it still reports an error in libvirtd.log.
error : qemuMonitorFindBalloonObjectPath:1042 : internal error: Cannot determine balloon device path
Apparently, if we don't set memballoon, we don't need to
set balloon device path.

Signed-off-by: Wang Yufei <james.wangyufei at huawei.com>
Signed-off-by: Zhang Bo <oscar.zhangbo at huawei.com>
---
 src/qemu/qemu_monitor.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index f959b74..c72702d 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -1711,7 +1711,9 @@ qemuMonitorGetMemoryStats(qemuMonitorPtr mon,
     QEMU_CHECK_MONITOR(mon);
 
     if (mon->json) {
-        ignore_value(qemuMonitorFindBalloonObjectPath(mon, "/"));
+        if (mon->vm->def->memballoon &&
+            mon->vm->def->memballoon->model != VIR_DOMAIN_MEMBALLOON_MODEL_NONE)
+            ignore_value(qemuMonitorFindBalloonObjectPath(mon, "/"));
         mon->ballooninit = true;
         return qemuMonitorJSONGetMemoryStats(mon, mon->balloonpath,
                                              stats, nr_stats);
-- 
1.7.12.4