fix: do not check watchers if staging rbd on node read only

internal/rbd/controllerserver.go

@@ -1123,3 +1123,18 @@ func (cs *ControllerServer) ControllerExpandVolume(ctx context.Context, req *csi
 		NodeExpansionRequired: nodeExpansion,
 	}, nil
 }
+
+// ControllerPublishVolume collects information useful for NodeStageVolume to tell if the volume is expected to be mounted readonly
+func (cs *ControllerServer) ControllerPublishVolume(ctx context.Context, req *csi.ControllerPublishVolumeRequest) (*csi.ControllerPublishVolumeResponse, error) {
+	ro := "false"
+	if req.GetReadonly() {
+		ro = "true"
+	}
+	// todo: check rwo and rox constains
+	return &csi.ControllerPublishVolumeResponse{PublishContext: map[string]string{"readonly": ro}}, nil
+}
+
+// ControllerUnpublishVolume does nothing
+func (cs *ControllerServer) ControllerUnpublishVolume(ctx context.Context, req *csi.ControllerUnpublishVolumeRequest) (*csi.ControllerUnpublishVolumeResponse, error) {
+	return &csi.ControllerUnpublishVolumeResponse{}, nil
+}

internal/rbd/driver.go

@@ -133,6 +133,8 @@ func (r *Driver) Run(conf *util.Config) {
 			csi.ControllerServiceCapability_RPC_CREATE_DELETE_SNAPSHOT,
 			csi.ControllerServiceCapability_RPC_CLONE_VOLUME,
 			csi.ControllerServiceCapability_RPC_EXPAND_VOLUME,
+			csi.ControllerServiceCapability_RPC_PUBLISH_READONLY,
+			csi.ControllerServiceCapability_RPC_PUBLISH_UNPUBLISH_VOLUME,
 		})
 		// We only support the multi-writer option when using block, but it's a supported capability for the plugin in general
 		// In addition, we want to add the remaining modes like MULTI_NODE_READER_ONLY,

internal/rbd/nodeserver.go

@@ -117,6 +117,8 @@ func (ns *NodeServer) NodeStageVolume(ctx context.Context, req *csi.NodeStageVol
 		return nil, err
 	}
 
+	readonly := req.GetPublishContext()["readonly"] == "true"
+
 	isBlock := req.GetVolumeCapability().GetBlock() != nil
 	disableInUseChecks := false
 	// MULTI_NODE_MULTI_WRITER is supported by default for Block access type volumes
@@ -126,7 +128,8 @@ func (ns *NodeServer) NodeStageVolume(ctx context.Context, req *csi.NodeStageVol
 			return nil, status.Error(codes.InvalidArgument, "rbd: RWX access mode request is only valid for volumes with access type `block`")
 		}
 
-		disableInUseChecks = true
+		// todo: if some of the watchers is r/w, we can not tell the differences
+		disableInUseChecks = readonly
 	}
 
 	volID := req.GetVolumeId()