kubernetes/vendor/github.com/moby/sys/mountinfo/mounted_linux.go

// MountedFast is a method of detecting a mount point without reading
// mountinfo from procfs. A caller can only trust the result if no error
// and sure == true are returned. Otherwise, other methods (e.g. parsing
// /proc/mounts) have to be used. If unsure, use Mounted instead (which
// uses MountedFast, but falls back to parsing mountinfo if needed).
//
// If a non-existent path is specified, an appropriate error is returned.
// In case the caller is not interested in this particular error, it should
// be handled separately using e.g. errors.Is(err, fs.ErrNotExist).
//
// This function is only available on Linux. When available (since kernel
// v5.6), openat2(2) syscall is used to reliably detect all mounts. Otherwise,
// the implementation falls back to using stat(2), which can reliably detect
// normal (but not bind) mounts.
func MountedFast(path string) (mounted, sure bool, err error) { … }

// mountedByOpenat2 is a method of detecting a mount that works for all kinds
// of mounts (incl. bind mounts), but requires a recent (v5.6+) linux kernel.
func mountedByOpenat2(path string) (bool, error) { … }

// mountedFast is similar to MountedFast, except it expects a normalized path.
func mountedFast(path string) (mounted, sure bool, err error) { … }

func mounted(path string) (bool, error) { … }