server: fix NPE for the case where volume is not attached to a VM (#3566)

Fixes NPE when trying to find suitable storage pools for a volume
when the volume is not attached to a VM.

Signed-off-by: Rohit Yadav <[email protected]>

Author: yadvr

server/src/main/java/com/cloud/server/ManagementServerImpl.java

@@ -37,8 +37,6 @@
 import javax.inject.Inject;
 import javax.naming.ConfigurationException;
 
-import com.cloud.storage.ScopeType;
-import com.cloud.hypervisor.kvm.dpdk.DpdkHelper;
 import org.apache.cloudstack.acl.ControlledEntity;
 import org.apache.cloudstack.affinity.AffinityGroupProcessor;
 import org.apache.cloudstack.affinity.dao.AffinityGroupVMMapDao;
@@ -613,6 +611,7 @@
 import com.cloud.hypervisor.HypervisorCapabilities;
 import com.cloud.hypervisor.HypervisorCapabilitiesVO;
 import com.cloud.hypervisor.dao.HypervisorCapabilitiesDao;
+import com.cloud.hypervisor.kvm.dpdk.DpdkHelper;
 import com.cloud.info.ConsoleProxyInfo;
 import com.cloud.network.IpAddress;
 import com.cloud.network.dao.IPAddressDao;
@@ -639,6 +638,7 @@
 import com.cloud.storage.GuestOSHypervisorVO;
 import com.cloud.storage.GuestOSVO;
 import com.cloud.storage.GuestOsCategory;
+import com.cloud.storage.ScopeType;
 import com.cloud.storage.StorageManager;
 import com.cloud.storage.StoragePool;
 import com.cloud.storage.Volume;
@@ -1442,7 +1442,11 @@ public Pair<List<? extends StoragePool>, List<? extends StoragePool>> listStorag
         StoragePool srcVolumePool = _poolDao.findById(volume.getPoolId());
         allPools = getAllStoragePoolCompatileWithVolumeSourceStoragePool(srcVolumePool);
         allPools.remove(srcVolumePool);
-        suitablePools = findAllSuitableStoragePoolsForVm(volume, vm, srcVolumePool);
+        if (vm != null) {
+            suitablePools = findAllSuitableStoragePoolsForVm(volume, vm, srcVolumePool);
+        } else {
+            suitablePools = allPools;
+        }
 
         return new Pair<List<? extends StoragePool>, List<? extends StoragePool>>(allPools, suitablePools);
     }