Add mount options to blockfile snapshotter

Signed-off-by: Derek McGowan <derek@mcg.dev>

snapshots/blockfile/blockfile_loopsetup_test.go

@@ -66,6 +66,8 @@ func setupSnapshotter(t *testing.T) ([]Opt, error) {
 
 	return []Opt{
 		WithScratchFile(scratch),
+		WithFSType("ext4"),
+		WithMountOptions([]string{"loop", "sync"}),
 	}, nil
 }