cgroups: support creating cgroupsv2 paths

drop the limitation of not supporting creating new cgroups v2 paths.
Every controller enabled /sys/fs/cgroup will be propagated down to the
created path.  This won't work for rootless cgroupsv2, but it is not
an issue for now, as this code is used only by CRI-O.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

1 files changed, 12 insertions, 7 deletions

diff --git a/pkg/cgroups/cpuset.go b/pkg/cgroups/cpuset.go
index 9aef493c9..25d2f7f76 100644
--- a/pkg/cgroups/cpuset.go
+++ b/pkg/cgroups/cpuset.go
@@ -14,19 +14,23 @@ import (
 type cpusetHandler struct {
 }
 
-func cpusetCopyFileFromParent(dir, file string) ([]byte, error) {
+func cpusetCopyFileFromParent(dir, file string, cgroupv2 bool) ([]byte, error) {
 	if dir == cgroupRoot {
 		return nil, fmt.Errorf("could not find parent to initialize cpuset %s", file)
 	}
 	path := filepath.Join(dir, file)
-	data, err := ioutil.ReadFile(path)
+	parentPath := path
+	if cgroupv2 {
+		parentPath = fmt.Sprintf("%s.effective", parentPath)
+	}
+	data, err := ioutil.ReadFile(parentPath)
 	if err != nil {
 		return nil, errors.Wrapf(err, "open %s", path)
 	}
 	if len(strings.Trim(string(data), "\n")) != 0 {
 		return data, nil
 	}
-	data, err = cpusetCopyFileFromParent(filepath.Dir(dir), file)
+	data, err = cpusetCopyFileFromParent(filepath.Dir(dir), file, cgroupv2)
 	if err != nil {
 		return nil, err
 	}
@@ -36,9 +40,9 @@ func cpusetCopyFileFromParent(dir, file string) ([]byte, error) {
 	return data, nil
 }
 
-func cpusetCopyFromParent(path string) error {
+func cpusetCopyFromParent(path string, cgroupv2 bool) error {
 	for _, file := range []string{"cpuset.cpus", "cpuset.mems"} {
-		if _, err := cpusetCopyFileFromParent(path, file); err != nil {
+		if _, err := cpusetCopyFileFromParent(path, file, cgroupv2); err != nil {
 			return err
 		}
 	}
@@ -60,14 +64,15 @@ func (c *cpusetHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) erro
 // Create the cgroup
 func (c *cpusetHandler) Create(ctr *CgroupControl) (bool, error) {
 	if ctr.cgroup2 {
-		return false, fmt.Errorf("cpuset create not implemented for cgroup v2")
+		path := filepath.Join(cgroupRoot, ctr.path)
+		return true, cpusetCopyFromParent(path, true)
 	}
 
 	created, err := ctr.createCgroupDirectory(CPUset)
 	if !created || err != nil {
 		return created, err
 	}
-	return true, cpusetCopyFromParent(ctr.getCgroupv1Path(CPUset))
+	return true, cpusetCopyFromParent(ctr.getCgroupv1Path(CPUset), false)
 }
 
 // Destroy the cgroup