diff --git a/content/oci/storage.go b/content/oci/storage.go
index 9a07a2ec..a1803e9a 100644
--- a/content/oci/storage.go
+++ b/content/oci/storage.go
@@ -44,7 +44,7 @@ var bufPool = sync.Pool{
 // Storage is a CAS based on file system with the OCI-Image layout.
 // Reference: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/image-layout.md
 type Storage struct {
-	rs *ReadOnlyStorage
+	*ReadOnlyStorage
 	// root is the root directory of the OCI layout.
 	root string
 	// ingestRoot is the root directory of the temporary ingest files.
@@ -59,20 +59,12 @@ func NewStorage(root string) (*Storage, error) {
 	}
 
 	return &Storage{
-		rs:         NewStorageFromFS(os.DirFS(rootAbs)),
-		root:       rootAbs,
-		ingestRoot: filepath.Join(rootAbs, "ingest"),
+		ReadOnlyStorage: NewStorageFromFS(os.DirFS(rootAbs)),
+		root:            rootAbs,
+		ingestRoot:      filepath.Join(rootAbs, "ingest"),
 	}, nil
 }
 
-func (s *Storage) Fetch(ctx context.Context, target ocispec.Descriptor) (io.ReadCloser, error) {
-	return s.rs.Fetch(ctx, target)
-}
-
-func (s *Storage) Exists(ctx context.Context, target ocispec.Descriptor) (bool, error) {
-	return s.rs.Exists(ctx, target)
-}
-
 // Push pushes the content, matching the expected descriptor.
 func (s *Storage) Push(_ context.Context, expected ocispec.Descriptor, content io.Reader) error {
 	path, err := blobPath(expected.Digest)