core: LSM: fix locking on restart

This patch fixes an issue when the engine is restarted during LSM,
the command gets stuck.

The cause of this issue was that EngineLocks were passed to
LiveMigrateDiskCommand, and from there to CreateSnapshotCommand in
the executeCommand() stage. There the locks are released, and
reacquired later on before snapshot remove phase. If the engine was
restarted during CreateSnapshot phase - both the CreateSnapshot and
LiveMigrateDisk commands resumed, running reacquireLocks, and then
before the Snapshot Remove phase, LiveMigrateDiskCommand attempted
to reacquire locks again, getting stuck.

In this patch we override reacquireLocks method in LiveMigrateDisk
command, doing nothing, and then the locks on Disk and VM are
acquired separately before the snapshot remove phase

Bug-Url: https://bugzilla.redhat.com/2110186

backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/storage/lsm/LiveMigrateDiskCommand.java

@@ -81,6 +81,7 @@
 import org.ovirt.engine.core.dao.StorageDomainDao;
 import org.ovirt.engine.core.dao.StorageDomainStaticDao;
 import org.ovirt.engine.core.dao.VmDao;
+import org.ovirt.engine.core.utils.lock.EngineLock;
 import org.ovirt.engine.core.utils.transaction.TransactionSupport;
 import org.ovirt.engine.core.vdsbroker.ResourceManager;
 import org.ovirt.engine.core.vdsbroker.builder.vminfo.VmInfoBuildUtils;
@@ -282,6 +283,8 @@ public boolean performNextOperation(int completedChildCount) {
             return true;
         }
 
+        EngineLock removeSnapshotLock = createEngineLockForSnapshotRemove();
+
         if (getParameters().getLiveDiskMigrateStage() == LiveDiskMigrateStage.LIVE_MIGRATE_DISK_EXEC_COMPLETED) {
             // This lock is required to prevent CreateSnapshotForVmCommand from
             // running at the same time as RemoveSnapshotCommand
@@ -290,7 +293,7 @@ public boolean performNextOperation(int completedChildCount) {
             // at the end of CreateSnapshotForVm command called from the executeCommand() method.
             // Here the lock is acquired again and will be released when this command (LiveMigrateDisk)
             // finishes.
-            if (!lockManager.acquireLock(getLock()).isAcquired()) {
+            if (!lockManager.acquireLock(removeSnapshotLock).isAcquired()) {
                 log.info("Failed to acquire VM lock, will retry on the next polling cycle");
                 return true;
             }
@@ -304,6 +307,8 @@ public boolean performNextOperation(int completedChildCount) {
             return true;
         }
 
+        lockManager.releaseLock(removeSnapshotLock);
+
         return false;
     }
 
@@ -726,17 +731,31 @@ public AuditLogType getAuditLogTypeValue() {
 
     @Override
     protected Map<String, Pair<String, String>> getExclusiveLocks() {
+        return Collections.emptyMap();
+    }
+
+    @Override
+    protected Map<String, Pair<String, String>> getSharedLocks() {
+        return Collections.emptyMap();
+    }
+
+    private Map<String, Pair<String, String>> getExclusiveLocksForSnapshotRemove() {
         return Collections.singletonMap(getParameters().getImageGroupID().toString(),
                 LockMessagesMatchUtil.makeLockingPair(LockingGroup.DISK,
                         getDiskIsBeingMigratedMessage(getDiskImageByDiskId(getParameters().getImageGroupID()))));
     }
 
-    @Override
-    protected Map<String, Pair<String, String>> getSharedLocks() {
+    private Map<String, Pair<String, String>> getSharedLocksForSnapshotRemove() {
         return Collections.singletonMap(getVmId().toString(),
                 LockMessagesMatchUtil.makeLockingPair(LockingGroup.VM, EngineMessage.ACTION_TYPE_FAILED_OBJECT_LOCKED));
     }
 
+    private EngineLock createEngineLockForSnapshotRemove() {
+        return new EngineLock(
+                getExclusiveLocksForSnapshotRemove(),
+                getSharedLocksForSnapshotRemove());
+    }
+
     private String getDiskIsBeingMigratedMessage(Disk disk) {
         return EngineMessage.ACTION_TYPE_FAILED_DISK_IS_BEING_MIGRATED.name()
                 + String.format("$DiskName %1$s", disk != null ? disk.getDiskAlias() : "");