3 files changed, 5 insertions, 3 deletions
diff --git a/pkg/sentry/fsimpl/ext/benchmark/benchmark_test.go b/pkg/sentry/fsimpl/ext/benchmark/benchmark_test.go
index c349b886e..2ee7cc7ac 100644
--- a/pkg/sentry/fsimpl/ext/benchmark/benchmark_test.go
+++ b/pkg/sentry/fsimpl/ext/benchmark/benchmark_test.go
@@ -70,6 +70,7 @@ func setUp(b *testing.B, imagePath string) (context.Context, *vfs.VirtualFilesys
 	}
 
 	root := mntns.Root()
+	root.IncRef()
 
 	tearDown := func() {
 		root.DecRef(ctx)
diff --git a/pkg/sentry/fsimpl/ext/ext.go b/pkg/sentry/fsimpl/ext/ext.go
index aca258d40..38fb7962b 100644
--- a/pkg/sentry/fsimpl/ext/ext.go
+++ b/pkg/sentry/fsimpl/ext/ext.go
@@ -38,9 +38,6 @@ const Name = "ext"
 // +stateify savable
 type FilesystemType struct{}
 
-// Compiles only if FilesystemType implements vfs.FilesystemType.
-var _ vfs.FilesystemType = (*FilesystemType)(nil)
-
 // getDeviceFd returns an io.ReaderAt to the underlying device.
 // Currently there are two ways of mounting an ext(2/3/4) fs:
 //   1. Specify a mount with our internal special MountType in the OCI spec.
@@ -101,6 +98,9 @@ func (FilesystemType) Name() string {
 	return Name
 }
 
+// Release implements vfs.FilesystemType.Release.
+func (FilesystemType) Release(ctx context.Context) {}
+
 // GetFilesystem implements vfs.FilesystemType.GetFilesystem.
 func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
 	// TODO(b/134676337): Ensure that the user is mounting readonly. If not,
diff --git a/pkg/sentry/fsimpl/ext/ext_test.go b/pkg/sentry/fsimpl/ext/ext_test.go
index 0989558cd..d9fd4590c 100644
--- a/pkg/sentry/fsimpl/ext/ext_test.go
+++ b/pkg/sentry/fsimpl/ext/ext_test.go
@@ -82,6 +82,7 @@ func setUp(t *testing.T, imagePath string) (context.Context, *vfs.VirtualFilesys
 	}
 
 	root := mntns.Root()
+	root.IncRef()
 
 	tearDown := func() {
 		root.DecRef(ctx)