cgroups: attempt a recursive rmdir

if the cgroup cannot be deleted, then attempt to delete all its
subdirectories and try again.

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

pkg/cgroups/blkio.go

@@ -37,7 +37,7 @@ func (c *blkioHandler) Create(ctr *CgroupControl) (bool, error) {
 
 // Destroy the cgroup
 func (c *blkioHandler) Destroy(ctr *CgroupControl) error {
-	return os.Remove(ctr.getCgroupv1Path(Blkio))
+	return rmDirRecursively(ctr.getCgroupv1Path(Blkio))
 }
 
 // Stat fills a metrics structure with usage stats for the controller

pkg/cgroups/cgroups.go

@@ -355,11 +355,40 @@ func (c *CgroupControl) Delete() error {
 	return c.DeleteByPath(c.path)
 }
 
+// rmDirRecursively delete recursively a cgroup directory.
+// It differs from os.RemoveAll as it doesn't attempt to unlink files.
+// On cgroupfs we are allowed only to rmdir empty directories.
+func rmDirRecursively(path string) error {
+	if err := os.Remove(path); err == nil || os.IsNotExist(err) {
+		return nil
+	}
+	entries, err := ioutil.ReadDir(path)
+	if err != nil {
+		return errors.Wrapf(err, "read %s", path)
+	}
+	for _, i := range entries {
+		if i.IsDir() {
+			if err := rmDirRecursively(filepath.Join(path, i.Name())); err != nil {
+				return err
+			}
+		}
+	}
+	if os.Remove(path); err != nil {
+		if !os.IsNotExist(err) {
+			return errors.Wrapf(err, "remove %s", path)
+		}
+	}
+	return nil
+}
+
 // DeleteByPath deletes the specified cgroup path
 func (c *CgroupControl) DeleteByPath(path string) error {
 	if c.systemd {
 		return systemdDestroy(path)
 	}
+	if c.cgroup2 {
+		return rmDirRecursively(filepath.Join(cgroupRoot, c.path))
+	}
 	var lastError error
 	for _, h := range handlers {
 		if err := h.Destroy(c); err != nil {
@@ -368,8 +397,11 @@ func (c *CgroupControl) DeleteByPath(path string) error {
 	}
 
 	for _, ctr := range c.additionalControllers {
+		if ctr.symlink {
+			continue
+		}
 		p := c.getCgroupv1Path(ctr.name)
-		if err := os.Remove(p); err != nil {
+		if err := rmDirRecursively(p); err != nil {
 			lastError = errors.Wrapf(err, "remove %s", p)
 		}
 	}

pkg/cgroups/cpu.go

@@ -68,7 +68,7 @@ func (c *cpuHandler) Create(ctr *CgroupControl) (bool, error) {
 
 // Destroy the cgroup
 func (c *cpuHandler) Destroy(ctr *CgroupControl) error {
-	return os.Remove(ctr.getCgroupv1Path(CPU))
+	return rmDirRecursively(ctr.getCgroupv1Path(CPU))
 }
 
 // Stat fills a metrics structure with usage stats for the controller

pkg/cgroups/cpuset.go

@@ -3,7 +3,6 @@ package cgroups
 import (
 	"fmt"
 	"io/ioutil"
-	"os"
 	"path/filepath"
 	"strings"
 
@@ -77,7 +76,7 @@ func (c *cpusetHandler) Create(ctr *CgroupControl) (bool, error) {
 
 // Destroy the cgroup
 func (c *cpusetHandler) Destroy(ctr *CgroupControl) error {
-	return os.Remove(ctr.getCgroupv1Path(CPUset))
+	return rmDirRecursively(ctr.getCgroupv1Path(CPUset))
 }
 
 // Stat fills a metrics structure with usage stats for the controller

pkg/cgroups/memory.go

@@ -2,7 +2,6 @@ package cgroups
 
 import (
 	"fmt"
-	"os"
 	"path/filepath"
 
 	spec "github.com/opencontainers/runtime-spec/specs-go"
@@ -33,7 +32,7 @@ func (c *memHandler) Create(ctr *CgroupControl) (bool, error) {
 
 // Destroy the cgroup
 func (c *memHandler) Destroy(ctr *CgroupControl) error {
-	return os.Remove(ctr.getCgroupv1Path(Memory))
+	return rmDirRecursively(ctr.getCgroupv1Path(Memory))
 }
 
 // Stat fills a metrics structure with usage stats for the controller

pkg/cgroups/pids.go

@@ -3,7 +3,6 @@ package cgroups
 import (
 	"fmt"
 	"io/ioutil"
-	"os"
 	"path/filepath"
 
 	spec "github.com/opencontainers/runtime-spec/specs-go"
@@ -40,7 +39,7 @@ func (c *pidHandler) Create(ctr *CgroupControl) (bool, error) {
 
 // Destroy the cgroup
 func (c *pidHandler) Destroy(ctr *CgroupControl) error {
-	return os.Remove(ctr.getCgroupv1Path(Pids))
+	return rmDirRecursively(ctr.getCgroupv1Path(Pids))
 }
 
 // Stat fills a metrics structure with usage stats for the controller