Improve Snapshot Finalization Ex. Handling (#49995)

* Improve Snapshot Finalization Ex. Handling

Like in #49989 we can get into a situation where the setting of
the repository generation (during snapshot finalization) in the cluster
state fails due to master failing over.
In this case we should not try to execute the next cluster state update
that will remove the snapshot from the cluster state.

Closes #49989

server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java

@@ -35,6 +35,7 @@ import org.elasticsearch.cluster.ClusterChangedEvent;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.ClusterStateApplier;
 import org.elasticsearch.cluster.ClusterStateUpdateTask;
+import org.elasticsearch.cluster.NotMasterException;
 import org.elasticsearch.cluster.RepositoryCleanupInProgress;
 import org.elasticsearch.cluster.RestoreInProgress;
 import org.elasticsearch.cluster.SnapshotDeletionsInProgress;
@@ -42,6 +43,7 @@ import org.elasticsearch.cluster.SnapshotsInProgress;
 import org.elasticsearch.cluster.SnapshotsInProgress.ShardSnapshotStatus;
 import org.elasticsearch.cluster.SnapshotsInProgress.ShardState;
 import org.elasticsearch.cluster.SnapshotsInProgress.State;
+import org.elasticsearch.cluster.coordination.FailedToCommitClusterStateException;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
 import org.elasticsearch.cluster.metadata.MetaData;
@@ -1051,8 +1053,16 @@ public class SnapshotsService extends AbstractLifecycleComponent implements Clus
             @Override
             public void onFailure(final Exception e) {
                 Snapshot snapshot = entry.snapshot();
-                logger.warn(() -> new ParameterizedMessage("[{}] failed to finalize snapshot", snapshot), e);
-                removeSnapshotFromClusterState(snapshot, null, e);
+                if (ExceptionsHelper.unwrap(e, NotMasterException.class, FailedToCommitClusterStateException.class) != null) {
+                    // Failure due to not being master any more, don't try to remove snapshot from cluster state the next master
+                    // will try ending this snapshot again
+                    logger.debug(() -> new ParameterizedMessage(
+                        "[{}] failed to update cluster state during snapshot finalization", snapshot), e);
+                    endingSnapshots.remove(snapshot);
+                } else {
+                    logger.warn(() -> new ParameterizedMessage("[{}] failed to finalize snapshot", snapshot), e);
+                    removeSnapshotFromClusterState(snapshot, null, e);
+                }
             }
         });
     }