nvmeof: add volume cloning capability

enable volume cloning support for nvmeof CSI driver by declaring
CLONE_VOLUME capability. The RBD backend automatically handles all
clone operations (snapshot-to-volume restore and volume-to-volume
cloning) when VolumeContentSource is present in CreateVolume request.

The NVMeoF driver adds debug logging to track clone operations and
creates namespaces pointing to the cloned RBD images. No changes to
the NVMeoF gateway are required since clones are transparent at the
block device level.

Signed-off-by: gadi-didi <gadi.didi@ibm.com>

Author: gadididi

internal/nvmeof/controller/controllerserver.go

@@ -118,7 +118,22 @@ func (cs *Server) CreateVolume(
 	}
 	defer cs.volumeLocks.Release(req.GetName())
 
+	// Extract clone source if present (for debug logging)
+	if contentSource := req.GetVolumeContentSource(); contentSource != nil {
+		switch contentSource.GetType().(type) {
+		case *csi.VolumeContentSource_Snapshot:
+			if snapshot := contentSource.GetSnapshot(); snapshot != nil {
+				log.DebugLog(ctx, "Creating volume from snapshot: %s", snapshot.GetSnapshotId())
+			}
+		case *csi.VolumeContentSource_Volume:
+			if vol := contentSource.GetVolume(); vol != nil {
+				log.DebugLog(ctx, "Creating volume clone from volume: %s", vol.GetVolumeId())
+			}
+		}
+	}
+
 	// Step 1: Create RBD volume through backend. if exists, it is ok.
+	// RBD backend automatically handles cloning when VolumeContentSource is present.
 	res, err := cs.backendServer.CreateVolume(ctx, req)
 	if err != nil {
 		log.ErrorLog(ctx, "failed to create RBD volume: %v", err)

internal/nvmeof/driver/driver.go

@@ -66,6 +66,7 @@ func (d *nvmeofDriver) Run(conf *util.Config) {
 			csi.ControllerServiceCapability_RPC_MODIFY_VOLUME,
 			csi.ControllerServiceCapability_RPC_EXPAND_VOLUME,
 			csi.ControllerServiceCapability_RPC_CREATE_DELETE_SNAPSHOT,
+			csi.ControllerServiceCapability_RPC_CLONE_VOLUME,
 		})
 
 		cd.AddVolumeCapabilityAccessModes([]csi.VolumeCapability_AccessMode_Mode{