Revert "Fix cgroup parent searching"

This reverts commit 2f9052ca29.

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

libcontainer/cgroups/fs/apply_raw.go

@@ -240,7 +240,7 @@ func (raw *data) parent(subsystem, mountpoint, src string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	relDir, err := filepath.Rel(initPath, src)
+	relDir, err := filepath.Rel(src, initPath)
 	if err != nil {
 		return "", err
 	}

libcontainer/cgroups/fs/apply_raw_test.go

@@ -1,29 +0,0 @@
-package fs
-
-import (
-	"path/filepath"
-	"testing"
-
-	"github.com/opencontainers/runc/libcontainer/cgroups"
-)
-
-func TestCgroupParent(t *testing.T) {
-	raw := &data{
-		cgroup: "",
-	}
-	subsystem := "memory"
-	subPath := "/docker/874e38c82a6c630dc95f3f1f2c8d8f43efb531d35a9f46154ab2fde1531b7bb6"
-	initPath, err := cgroups.GetInitCgroupDir(subsystem)
-	if err != nil {
-		t.Fatal(err)
-	}
-	srcPath := filepath.Join(initPath, subPath)
-	cgPath := "/sys/fs/cgroup/memory"
-	path, err := raw.parent(subsystem, cgPath, srcPath)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if path != filepath.Join(cgPath, subPath) {
-		t.Fatalf("Unexpected path: %s, should be %s", path, filepath.Join(cgPath, subPath))
-	}
-}