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/os.go

@@ -40,6 +40,7 @@ type OS interface {
 	WriteFile(filename string, data []byte, perm os.FileMode) error
 	Mount(source string, target string, fstype string, flags uintptr, data string) error
 	Unmount(target string, flags int) error
+	GetMounts() ([]*mount.Info, error)
 }
 
 // RealOS is used to dispatch the real system level operations.
@@ -114,3 +115,8 @@ func (RealOS) Unmount(target string, flags int) error {
 	}
 	return unix.Unmount(target, flags)
 }
+
+// GetMounts retrieves a list of mounts for the current running process.
+func (RealOS) GetMounts() ([]*mount.Info, error) {
+	return mount.GetMounts()
+}