core: fix cephfs pvc network fencing

The cephfs PVC might exist on the kubernetes
node object but due to some timing issues the
ip might not be visible on the ceph cluster or
the client might already got evicted or disconnected
from ceph cluster. In this case we will not be
able to get IP details for the subvolume and we dont
have any check for empty ip's in the code and rook
tries to create NetworkFence CR with empty Ip's
and the NetworkFence will get moved to the Failed state.
This PR adds the necessary check and logging to prevent
this one.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

pkg/operator/ceph/cluster/watcher.go

@@ -438,10 +438,15 @@ func (c *clientCluster) fenceCephFSVolume(
 		return fmt.Errorf("failed to list watchers for cephfs pool/subvoumeName %s/%s. %v", cephFSPV.Spec.CSI.VolumeAttributes["pool"], cephFSPV.Spec.CSI.VolumeAttributes["subvolumeName"], err)
 	}
 	ips, err := cephFSMDSClientMarshal(buf, cephFSPV)
-	if err != nil || ips == nil {
+	if err != nil {
 		return fmt.Errorf("failed to unmarshal cephfs mds  output. %v", err)
 	}
 
+	if len(ips) == 0 {
+		logger.Infof("no active mds clients found for cephfs volume %q", cephFSPV.Name)
+		return nil
+	}
+
 	err = c.createNetworkFence(ctx, cephFSPV, node, cluster, ips, cephfsDriver)
 	if err != nil {
 		return fmt.Errorf("failed to create network fence for node %q. %v", node.Name, err)

pkg/operator/ceph/cluster/watcher_test.go

@@ -179,7 +179,7 @@ func TestHandleNodeFailure(t *testing.T) {
 		case command == "ceph" && args[0] == "status":
 			return `{"entity":[{"addr": [{"addr": "10.244.0.12:0", "nonce":3247243972}]}], "client_metadata":{"root":"/"}}`, nil
 		case command == "ceph" && args[0] == "tell":
-			return `[{"entity":{"addr":{"addr":"10.244.0.12:0","nonce":3247243972}}, "client_metadata":{"root":"/"}}]`, nil
+			return `[{"entity":{"addr":{"addr":"10.244.0.12:0","nonce":3247243972}}, "client_metadata":{"root":"/volumes/csi/csi-vol-58469d41-f6c0-4720-b23a-0a0826b842ca"}}]`, nil
 
 		}
 		return "", errors.Errorf("unexpected rbd/ceph command %q", args)
@@ -250,6 +250,7 @@ func TestHandleNodeFailure(t *testing.T) {
 					VolumeHandle: "0001-0009-rook-ceph-0000000000000002-24862838-240d-4215-9183-abfc0e9e4001",
 					VolumeAttributes: map[string]string{
 						"fsName":        "myfs",
+						"subvolumePath": "/volumes/csi/csi-vol-58469d41-f6c0-4720-b23a-0a0826b842ca",
 						"subvolumeName": "csi-vol-58469d41-f6c0-4720-b23a-0a0826b842ca",
 					},
 				},