libct/cg/fs.getMount: reuse cgroups.GetCgroupMountinfo

Reuse cgroups.GetCgroupMountinfo instead of parsing mountinfo directly.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/cgroups/fs/cpuset.go

@@ -7,8 +7,8 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"strings"
 
-	"github.com/moby/sys/mountinfo"
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
 	"github.com/opencontainers/runc/libcontainer/configs"
@@ -47,19 +47,23 @@ func (s *CpusetGroup) GetStats(path string, stats *cgroups.Stats) error {
 
 // Get the source mount point of directory passed in as argument.
 func getMount(dir string) (string, error) {
-	mi, err := mountinfo.GetMounts(mountinfo.ParentsFilter(dir))
+	mi, err := cgroups.ReadCgroupMountinfo()
 	if err != nil {
 		return "", err
 	}
 	if len(mi) < 1 {
 		return "", errors.Errorf("Can't find mount point of %s", dir)
 	}
 
-	// find the longest mount point
+	// find the longest mount point which can be a parent of dir
 	var idx, maxlen int
 	for i := range mi {
-		if len(mi[i].Mountpoint) > maxlen {
-			maxlen = len(mi[i].Mountpoint)
+		mp := mi[i].Mountpoint
+		if !strings.HasPrefix(dir, mp) {
+			continue
+		}
+		if len(mp) > maxlen {
+			maxlen = len(mp)
 			idx = i
 		}
 	}