CLOUDSTACK-8663: Fixed various issues to allow VM snapshots and volume

snapshots to exist together

Reverting VM to disk only snapshot in Xenserver corrupts VM

Stale NFS secondary storage on XS leads to volume creation failure from snapshot

plugins/hypervisors/xenserver/src/com/cloud/hypervisor/xenserver/resource/CitrixResourceBase.java

@@ -29,6 +29,8 @@ import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.nio.charset.Charset;
+
+import org.apache.commons.collections.MapUtils;
 import org.joda.time.Duration;
 import java.util.ArrayList;
 import java.util.Date;
@@ -1415,6 +1417,10 @@ public abstract class CitrixResourceBase implements ServerResource, HypervisorRe
             vbdr.userdevice = "autodetect";
             vbdr.mode = Types.VbdMode.RW;
             vbdr.type = Types.VbdType.DISK;
+            Long deviceId = volumeTO.getDeviceId();
+            if (deviceId != null && (!isDeviceUsed(conn, vm, deviceId) || deviceId > 3)) {
+                vbdr.userdevice = deviceId.toString();
+            }
             VBD.create(conn, vbdr);
         }
         return vm;
@@ -4350,6 +4356,30 @@ public abstract class CitrixResourceBase implements ServerResource, HypervisorRe
         }
     }
 
+    protected void skipOrRemoveSR(Connection conn, SR sr) {
+        if (sr == null) {
+            return;
+        }
+        if (s_logger.isDebugEnabled()) {
+            s_logger.debug(logX(sr, "Removing SR"));
+        }
+        try {
+            Set<VDI> vdis = sr.getVDIs(conn);
+            for (VDI vdi : vdis) {
+                if (MapUtils.isEmpty(vdi.getCurrentOperations(conn))) {
+                    continue;
+                }
+                return;
+            }
+            removeSR(conn, sr);
+            return;
+        } catch (XenAPIException | XmlRpcException e) {
+            s_logger.warn(logX(sr, "Unable to get current opertions " + e.toString()), e);
+        }
+        String msg = "Remove SR failed";
+        s_logger.warn(msg);
+    }
+
     public void removeSR(final Connection conn, final SR sr) {
         if (sr == null) {
             return;

plugins/hypervisors/xenserver/src/com/cloud/hypervisor/xenserver/resource/XenServerStorageProcessor.java

@@ -1199,7 +1199,7 @@ public class XenServerStorageProcessor implements StorageProcessor {
             final Set<VDI> snapshots = volume.getSnapshots(conn);
             for (final VDI snapshot : snapshots) {
                 try {
-                    if (!snapshot.getUuid(conn).equals(avoidSnapshotUuid) && snapshot.getSnapshotTime(conn).before(avoidSnapshot.getSnapshotTime(conn))) {
+                    if (!snapshot.getUuid(conn).equals(avoidSnapshotUuid) && snapshot.getSnapshotTime(conn).before(avoidSnapshot.getSnapshotTime(conn)) && snapshot.getVBDs(conn).isEmpty()) {
                         snapshot.destroy(conn);
                     }
                 } catch (final Exception e) {

plugins/hypervisors/xenserver/src/com/cloud/hypervisor/xenserver/resource/Xenserver625StorageProcessor.java

@@ -738,7 +738,7 @@ public class Xenserver625StorageProcessor extends XenServerStorageProcessor {
             s_logger.warn(details, e);
         } finally {
             if (srcSr != null) {
-                hypervisorResource.removeSR(conn, srcSr);
+                hypervisorResource.skipOrRemoveSR(conn, srcSr);
             }
             if (!result && destVdi != null) {
                 try {

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

@@ -2146,13 +2146,6 @@ public class VolumeApiServiceImpl extends ManagerBase implements VolumeApiServic
             throw new InvalidParameterValueException("Can't find zone by id " + volume.getDataCenterId());
         }
 
-        if (volume.getInstanceId() != null) {
-            // Check that Vm to which this volume is attached does not have VM Snapshots
-            if (_vmSnapshotDao.findByVm(volume.getInstanceId()).size() > 0) {
-                throw new InvalidParameterValueException("Volume snapshot is not allowed, please detach it from VM with VM Snapshots");
-            }
-        }
-
         if (Grouping.AllocationState.Disabled == zone.getAllocationState() && !_accountMgr.isRootAdmin(caller.getId())) {
             throw new PermissionDeniedException("Cannot perform this operation, Zone is currently disabled: " + zone.getName());
         }

server/src/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java

@@ -263,11 +263,6 @@ public class VMSnapshotManagerImpl extends MutualExclusiveIdsManagerBase impleme
             throw new InvalidParameterValueException("Creating VM snapshot failed due to VM:" + vmId + " is a system VM or does not exist");
         }
 
-        if (_snapshotDao.listByInstanceId(vmId, Snapshot.State.BackedUp).size() > 0) {
-            throw new InvalidParameterValueException(
-                    "VM snapshot for this VM is not allowed. This VM has volumes attached which has snapshots, please remove all snapshots before taking VM snapshot");
-        }
-
         // VM snapshot with memory is not supported for VGPU Vms
         if (snapshotMemory && _serviceOfferingDetailsDao.findDetail(userVmVo.getServiceOfferingId(), GPU.Keys.vgpuType.toString()) != null) {
             throw new InvalidParameterValueException("VM snapshot with MEMORY is not supported for vGPU enabled VMs.");