common/pkg/cgroups: Remove linuxCpusetHandler.Create and cpusetCopyFromParent

The manual cpusetCopyFromParent function was needed for cgroups v1 to
populate cpuset.cpus and cpuset.mems from parent cgroups. In cgroups v2,
the kernel automatically handles cpuset inheritance through the
cpuset.cpus.effective and cpuset.mems.effective interfaces.

When fs2.NewManager().Set() is called with cpuset resources, it directly
writes the values to cpuset.cpus and cpuset.mems if provided. If not
provided, the kernel ensures child cgroups have valid effective cpusets by
automatically inheriting from their parent.

Signed-off-by: Lokesh Mandvekar <[email protected]>

Author: lsm5

common/pkg/cgroups/cgroups_linux.go

@@ -445,46 +445,6 @@ func cleanString(s string) string {
 	return strings.Trim(s, "\n")
 }
 
-func cpusetCopyFromParent(path string, cgroupv2 bool) error {
-	for _, file := range []string{"cpuset.cpus", "cpuset.mems"} {
-		if _, err := cpusetCopyFileFromParent(path, file, cgroupv2); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-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)
-	parentPath := path
-	if cgroupv2 {
-		parentPath += ".effective"
-	}
-	data, err := os.ReadFile(parentPath)
-	if err != nil {
-		// if the file doesn't exist, it is likely that the cpuset controller
-		// is not enabled in the kernel.
-		if os.IsNotExist(err) {
-			return nil, nil
-		}
-		return nil, err
-	}
-	if strings.Trim(string(data), "\n") != "" {
-		return data, nil
-	}
-	data, err = cpusetCopyFileFromParent(filepath.Dir(dir), file, cgroupv2)
-	if err != nil {
-		return nil, err
-	}
-	if err := os.WriteFile(path, data, 0o644); err != nil {
-		return nil, fmt.Errorf("write %s: %w", path, err)
-	}
-	return data, nil
-}
-
 // SystemCPUUsage returns the system usage for all the cgroups.
 func SystemCPUUsage() (uint64, error) {
 	_, err := IsCgroup2UnifiedMode()

common/pkg/cgroups/cpuset_linux.go

@@ -27,12 +27,6 @@ func (c *linuxCpusetHandler) Apply(ctr *CgroupControl, res *cgroups.Resources) e
 	return man.Set(res)
 }
 
-// Create the cgroup.
-func (c *linuxCpusetHandler) Create(ctr *CgroupControl) (bool, error) {
-	path := filepath.Join(cgroupRoot, ctr.config.Path)
-	return true, cpusetCopyFromParent(path, true)
-}
-
 // Stat fills a metrics structure with usage stats for the controller.
 func (c *linuxCpusetHandler) Stat(_ *CgroupControl, _ *cgroups.Stats) error {
 	return nil