Fix detach volume on stopped Vms

Author: nvazquez

server/src/main/java/com/cloud/storage/VolumeApiServiceImpl.java

@@ -2054,31 +2054,35 @@ private Volume orchestrateDetachVolumeFromVM(long vmId, long volumeId) {
         if (!sendCommand || (answer != null && answer.getResult())) {
             // Mark the volume as detached
             _volsDao.detachVolume(volume.getId());
-            String datastoreName = answer.getContextParam("datastoreName");
-            if (datastoreName != null) {
-                StoragePoolVO storagePoolVO = _storagePoolDao.findByUuid(datastoreName);
-                if (storagePoolVO != null) {
+
+            if (answer != null) {
+                String datastoreName = answer.getContextParam("datastoreName");
+                if (datastoreName != null) {
+                    StoragePoolVO storagePoolVO = _storagePoolDao.findByUuid(datastoreName);
+                    if (storagePoolVO != null) {
+                        VolumeVO volumeVO = _volsDao.findById(volumeId);
+                        volumeVO.setPoolId(storagePoolVO.getId());
+                        _volsDao.update(volumeVO.getId(), volumeVO);
+                    } else {
+                        s_logger.warn(String.format("Unable to find datastore %s while updating the new datastore of the volume %d", datastoreName, volumeId));
+                    }
+                }
+
+                String volumePath = answer.getContextParam("volumePath");
+                if (volumePath != null) {
                     VolumeVO volumeVO = _volsDao.findById(volumeId);
-                    volumeVO.setPoolId(storagePoolVO.getId());
+                    volumeVO.setPath(volumePath);
                     _volsDao.update(volumeVO.getId(), volumeVO);
-                } else {
-                    s_logger.warn(String.format("Unable to find datastore %s while updating the new datastore of the volume %d", datastoreName, volumeId));
                 }
-            }
 
-            String volumePath = answer.getContextParam("volumePath");
-            if (volumePath != null) {
-                VolumeVO volumeVO = _volsDao.findById(volumeId);
-                volumeVO.setPath(volumePath);
-                _volsDao.update(volumeVO.getId(), volumeVO);
+                String chainInfo = answer.getContextParam("chainInfo");
+                if (chainInfo != null) {
+                    VolumeVO volumeVO = _volsDao.findById(volumeId);
+                    volumeVO.setChainInfo(chainInfo);
+                    _volsDao.update(volumeVO.getId(), volumeVO);
+                }
             }
 
-            String chainInfo = answer.getContextParam("chainInfo");
-            if (chainInfo != null) {
-                VolumeVO volumeVO = _volsDao.findById(volumeId);
-                volumeVO.setChainInfo(chainInfo);
-                _volsDao.update(volumeVO.getId(), volumeVO);
-            }
             // volume.getPoolId() should be null if the VM we are detaching the disk from has never been started before
             if (volume.getPoolId() != null) {
                 DataStore dataStore = dataStoreMgr.getDataStore(volume.getPoolId(), DataStoreRole.Primary);