Merge pull request #3506 from giuseppe/cgroup2-improvements

cgroups: support creating cgroupsv2 paths

6 files changed, 78 insertions, 17 deletions

diff --git a/pkg/cgroups/blkio.go b/pkg/cgroups/blkio.go
index ca9107d97..9c2a811d9 100644
--- a/pkg/cgroups/blkio.go
+++ b/pkg/cgroups/blkio.go
@@ -30,7 +30,7 @@ func (c *blkioHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) error
 // Create the cgroup
 func (c *blkioHandler) Create(ctr *CgroupControl) (bool, error) {
 	if ctr.cgroup2 {
-		return false, fmt.Errorf("io create not implemented for cgroup v2")
+		return false, nil
 	}
 	return ctr.createCgroupDirectory(Blkio)
 }
diff --git a/pkg/cgroups/cgroups.go b/pkg/cgroups/cgroups.go
index d6c19212b..1dad45d7f 100644
--- a/pkg/cgroups/cgroups.go
+++ b/pkg/cgroups/cgroups.go
@@ -149,6 +149,51 @@ func (c *CgroupControl) getCgroupv1Path(name string) string {
 	return filepath.Join(cgroupRoot, name, c.path)
 }
 
+// createCgroupv2Path creates the cgroupv2 path and enables all the available controllers
+func createCgroupv2Path(path string) (Err error) {
+	content, err := ioutil.ReadFile("/sys/fs/cgroup/cgroup.controllers")
+	if err != nil {
+		return errors.Wrapf(err, "read /sys/fs/cgroup/cgroup.controllers")
+	}
+	if !filepath.HasPrefix(path, "/sys/fs/cgroup") {
+		return fmt.Errorf("invalid cgroup path %s", path)
+	}
+
+	res := ""
+	for i, c := range strings.Split(strings.TrimSpace(string(content)), " ") {
+		if i == 0 {
+			res = fmt.Sprintf("+%s", c)
+		} else {
+			res = res + fmt.Sprintf(" +%s", c)
+		}
+	}
+	resByte := []byte(res)
+
+	current := "/sys/fs"
+	elements := strings.Split(path, "/")
+	for i, e := range elements[3:] {
+		current = filepath.Join(current, e)
+		if i > 0 {
+			if err := os.Mkdir(current, 0755); err != nil {
+				if !os.IsExist(err) {
+					return errors.Wrapf(err, "mkdir %s", path)
+				}
+			} else {
+				// If the directory was created, be sure it is not left around on errors.
+				defer func() {
+					if Err != nil {
+						os.Remove(current)
+					}
+				}()
+			}
+		}
+		if err := ioutil.WriteFile(filepath.Join(current, "cgroup.subtree_control"), resByte, 0755); err != nil {
+			return errors.Wrapf(err, "write %s", filepath.Join(current, "cgroup.subtree_control"))
+		}
+	}
+	return nil
+}
+
 // initialize initializes the specified hierarchy
 func (c *CgroupControl) initialize() (err error) {
 	createdSoFar := map[string]controllerHandler{}
@@ -161,6 +206,11 @@ func (c *CgroupControl) initialize() (err error) {
 			}
 		}
 	}()
+	if c.cgroup2 {
+		if err := createCgroupv2Path(filepath.Join(cgroupRoot, c.path)); err != nil {
+			return errors.Wrapf(err, "error creating cgroup path %s", c.path)
+		}
+	}
 	for name, handler := range handlers {
 		created, err := handler.Create(c)
 		if err != nil {
@@ -341,7 +391,7 @@ func (c *CgroupControl) AddPid(pid int) error {
 	pidString := []byte(fmt.Sprintf("%d\n", pid))
 
 	if c.cgroup2 {
-		p := filepath.Join(cgroupRoot, c.path, "tasks")
+		p := filepath.Join(cgroupRoot, c.path, "cgroup.procs")
 		if err := ioutil.WriteFile(p, pidString, 0644); err != nil {
 			return errors.Wrapf(err, "write %s", p)
 		}
diff --git a/pkg/cgroups/cpu.go b/pkg/cgroups/cpu.go
index 8640d490e..1c8610cc4 100644
--- a/pkg/cgroups/cpu.go
+++ b/pkg/cgroups/cpu.go
@@ -61,7 +61,7 @@ func (c *cpuHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) error {
 // Create the cgroup
 func (c *cpuHandler) Create(ctr *CgroupControl) (bool, error) {
 	if ctr.cgroup2 {
-		return false, fmt.Errorf("cpu create not implemented for cgroup v2")
+		return false, nil
 	}
 	return ctr.createCgroupDirectory(CPU)
 }
@@ -98,15 +98,24 @@ func (c *cpuHandler) Stat(ctr *CgroupControl, m *Metrics) error {
 	} else {
 		usage.Total, err = readAcct(ctr, "cpuacct.usage")
 		if err != nil {
-			return err
+			if !os.IsNotExist(errors.Cause(err)) {
+				return err
+			}
+			usage.Total = 0
 		}
 		usage.Kernel, err = readAcct(ctr, "cpuacct.usage_sys")
 		if err != nil {
-			return err
+			if !os.IsNotExist(errors.Cause(err)) {
+				return err
+			}
+			usage.Kernel = 0
 		}
 		usage.PerCPU, err = readAcctList(ctr, "cpuacct.usage_percpu")
 		if err != nil {
-			return err
+			if !os.IsNotExist(errors.Cause(err)) {
+				return err
+			}
+			usage.PerCPU = nil
 		}
 	}
 	m.CPU = CPUMetrics{Usage: usage}
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
diff --git a/pkg/cgroups/memory.go b/pkg/cgroups/memory.go
index 0505eac40..80e88d17c 100644
--- a/pkg/cgroups/memory.go
+++ b/pkg/cgroups/memory.go
@@ -26,7 +26,7 @@ func (c *memHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) error {
 // Create the cgroup
 func (c *memHandler) Create(ctr *CgroupControl) (bool, error) {
 	if ctr.cgroup2 {
-		return false, fmt.Errorf("memory create not implemented for cgroup v2")
+		return false, nil
 	}
 	return ctr.createCgroupDirectory(Memory)
 }
diff --git a/pkg/cgroups/pids.go b/pkg/cgroups/pids.go
index c90dc1c02..ffbde100d 100644
--- a/pkg/cgroups/pids.go
+++ b/pkg/cgroups/pids.go
@@ -35,9 +35,6 @@ func (c *pidHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) error {
 
 // Create the cgroup
 func (c *pidHandler) Create(ctr *CgroupControl) (bool, error) {
-	if ctr.cgroup2 {
-		return false, fmt.Errorf("pid create not implemented for cgroup v2")
-	}
 	return ctr.createCgroupDirectory(Pids)
 }