Ensure the mount point is propagated

mount with `rshared`, the host path should be shared.
mount with `rslave`, the host pash should be shared or slave.

Signed-off-by: Yanqiang Miao <miao.yanqiang@zte.com.cn>

pkg/os/testing/fake_os.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"sync"
 
+	"github.com/docker/docker/pkg/mount"
 	"golang.org/x/net/context"
 
 	osInterface "github.com/kubernetes-incubator/cri-containerd/pkg/os"
@@ -48,6 +49,7 @@ type FakeOS struct {
 	WriteFileFn           func(string, []byte, os.FileMode) error
 	MountFn               func(source string, target string, fstype string, flags uintptr, data string) error
 	UnmountFn             func(target string, flags int) error
+	GetMountsFn           func() ([]*mount.Info, error)
 	calls                 []CalledDetail
 	errors                map[string]error
 }
@@ -225,3 +227,16 @@ func (f *FakeOS) Unmount(target string, flags int) error {
 	}
 	return nil
 }
+
+// GetMounts retrieves a list of mounts for the current running process.
+func (f *FakeOS) GetMounts() ([]*mount.Info, error) {
+	f.appendCalls("GetMounts")
+	if err := f.getError("GetMounts"); err != nil {
+		return nil, err
+	}
+
+	if f.GetMountsFn != nil {
+		return f.GetMountsFn()
+	}
+	return nil, nil
+}