diff --git a/internal/csi-addons/rbd/reclaimspace.go b/internal/csi-addons/rbd/reclaimspace.go
new file mode 100644
index 000000000..7ef7e1716
--- /dev/null
+++ b/internal/csi-addons/rbd/reclaimspace.go
@@ -0,0 +1,74 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rbd
+
+import (
+	"context"
+
+	rbdutil "github.com/ceph/ceph-csi/internal/rbd"
+	"github.com/ceph/ceph-csi/internal/util"
+
+	rs "github.com/csi-addons/spec/lib/go/reclaimspace"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// ReclaimSpaceControllerServer struct of rbd CSI driver with supported methods
+// of CSI-addons reclaimspace controller service spec.
+type ReclaimSpaceControllerServer struct {
+	*rs.UnimplementedReclaimSpaceControllerServer
+}
+
+// NewReclaimSpaceControllerServer creates a new IdentityServer which handles
+// the Identity Service requests from the CSI-Addons specification.
+func NewReclaimSpaceControllerServer() *ReclaimSpaceControllerServer {
+	return &ReclaimSpaceControllerServer{}
+}
+
+func (rscs *ReclaimSpaceControllerServer) RegisterService(server grpc.ServiceRegistrar) {
+	rs.RegisterReclaimSpaceControllerServer(server, rscs)
+}
+
+func (rscs *ReclaimSpaceControllerServer) ControllerReclaimSpace(
+	ctx context.Context,
+	req *rs.ControllerReclaimSpaceRequest) (*rs.ControllerReclaimSpaceResponse, error) {
+	volumeID := req.GetVolumeId()
+	if volumeID == "" {
+		return nil, status.Error(codes.InvalidArgument, "empty volume ID in request")
+	}
+
+	cr, err := util.NewUserCredentials(req.GetSecrets())
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	defer cr.DeleteCredentials()
+
+	rbdVol, err := rbdutil.GenVolFromVolID(ctx, volumeID, cr, req.GetSecrets())
+	if err != nil {
+		return nil, status.Errorf(codes.Aborted, "failed to find volume with ID %q: %s", volumeID, err.Error())
+	}
+	defer rbdVol.Destroy()
+
+	err = rbdVol.Sparsify()
+	if err != nil {
+		// TODO: check for different error codes?
+		return nil, status.Errorf(codes.Internal, "failed to sparsify volume %q: %s", rbdVol, err.Error())
+	}
+
+	return &rs.ControllerReclaimSpaceResponse{}, nil
+}
diff --git a/internal/csi-addons/rbd/reclaimspace_test.go b/internal/csi-addons/rbd/reclaimspace_test.go
new file mode 100644
index 000000000..18c67c6db
--- /dev/null
+++ b/internal/csi-addons/rbd/reclaimspace_test.go
@@ -0,0 +1,43 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rbd
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	rs "github.com/csi-addons/spec/lib/go/reclaimspace"
+)
+
+// TestControllerReclaimSpace is a minimal test for the
+// ControllerReclaimSpace() procedure. During unit-testing, there is no Ceph
+// cluster available, so actual operations can not be performed.
+func TestControllerReclaimSpace(t *testing.T) {
+	t.Parallel()
+
+	controller := NewReclaimSpaceControllerServer()
+
+	req := &rs.ControllerReclaimSpaceRequest{
+		VolumeId: "",
+		Secrets:  nil,
+	}
+
+	_, err := controller.ControllerReclaimSpace(context.TODO(), req)
+	assert.Error(t, err)
+}
diff --git a/internal/rbd/diskusage.go b/internal/rbd/diskusage.go
new file mode 100644
index 000000000..efb12f37c
--- /dev/null
+++ b/internal/rbd/diskusage.go
@@ -0,0 +1,44 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rbd
+
+import (
+	"fmt"
+)
+
+// Sparsify checks the size of the objects in the RBD image and calls
+// rbd_sparify() to free zero-filled blocks and reduce the storage consumption
+// of the image.
+func (ri *rbdImage) Sparsify() error {
+	image, err := ri.open()
+	if err != nil {
+		return err
+	}
+	defer image.Close()
+
+	imageInfo, err := image.Stat()
+	if err != nil {
+		return err
+	}
+
+	err = image.Sparsify(1 << imageInfo.Order)
+	if err != nil {
+		return fmt.Errorf("failed to sparsify image: %w", err)
+	}
+
+	return nil
+}