util: drop IsCgroup2UnifiedMode and use it from cgroups

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

cmd/podman/libpodruntime/runtime.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/pkg/cgroups"
 	"github.com/containers/libpod/pkg/namespaces"
 	"github.com/containers/libpod/pkg/rootless"
 	"github.com/containers/libpod/pkg/util"
@@ -112,7 +113,7 @@ func getRuntime(ctx context.Context, c *cliconfig.PodmanCommand, renumber bool,
 	if c.Flags().Changed("cgroup-manager") {
 		options = append(options, libpod.WithCgroupManager(c.GlobalFlags.CGroupManager))
 	} else {
-		unified, err := util.IsCgroup2UnifiedMode()
+		unified, err := cgroups.IsCgroup2UnifiedMode()
 		if err != nil {
 			return nil, err
 		}

cmd/podman/main_local.go

@@ -13,6 +13,7 @@ import (
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/cmd/podman/libpodruntime"
 	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/pkg/cgroups"
 	"github.com/containers/libpod/pkg/rootless"
 	"github.com/containers/libpod/pkg/tracing"
 	"github.com/containers/libpod/pkg/util"
@@ -31,7 +32,7 @@ func init() {
 		cgroupManager = runtimeConfig.CgroupManager
 	}
 	cgroupHelp := "Cgroup manager to use (cgroupfs or systemd)"
-	cgroupv2, _ := util.IsCgroup2UnifiedMode()
+	cgroupv2, _ := cgroups.IsCgroup2UnifiedMode()
 	if rootless.IsRootless() && !cgroupv2 {
 		cgroupManager = ""
 		cgroupHelp = "Cgroup manager is not supported in rootless mode"

cmd/podman/shared/create_cli.go

@@ -5,9 +5,9 @@ import (
 	"strings"
 
 	"github.com/containers/libpod/cmd/podman/shared/parse"
+	"github.com/containers/libpod/pkg/cgroups"
 	cc "github.com/containers/libpod/pkg/spec"
 	"github.com/containers/libpod/pkg/sysinfo"
-	"github.com/containers/libpod/pkg/util"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
@@ -78,7 +78,7 @@ func addWarning(warnings []string, msg string) []string {
 func verifyContainerResources(config *cc.CreateConfig, update bool) ([]string, error) {
 	warnings := []string{}
 
-	cgroup2, err := util.IsCgroup2UnifiedMode()
+	cgroup2, err := cgroups.IsCgroup2UnifiedMode()
 	if err != nil || cgroup2 {
 		return warnings, err
 	}

pkg/spec/spec.go

@@ -6,8 +6,8 @@ import (
 	"strings"
 
 	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/pkg/cgroups"
 	"github.com/containers/libpod/pkg/rootless"
-	"github.com/containers/libpod/pkg/util"
 	pmount "github.com/containers/storage/pkg/mount"
 	"github.com/docker/docker/oci/caps"
 	"github.com/docker/go-units"
@@ -350,7 +350,7 @@ func (config *CreateConfig) createConfigToOCISpec(runtime *libpod.Runtime, userM
 	}
 
 	if rootless.IsRootless() {
-		cgroup2, err := util.IsCgroup2UnifiedMode()
+		cgroup2, err := cgroups.IsCgroup2UnifiedMode()
 		if err != nil {
 			return nil, err
 		}

pkg/util/utils_supported.go

@@ -11,33 +11,9 @@ import (
 	"github.com/pkg/errors"
 	"os"
 	"path/filepath"
-	"sync"
 	"syscall"
 )
 
-const (
-	_cgroup2SuperMagic = 0x63677270
-)
-
-var (
-	isUnifiedOnce sync.Once
-	isUnified     bool
-	isUnifiedErr  error
-)
-
-// IsCgroup2UnifiedMode returns whether we are running in cgroup 2 unified mode.
-func IsCgroup2UnifiedMode() (bool, error) {
-	isUnifiedOnce.Do(func() {
-		var st syscall.Statfs_t
-		if err := syscall.Statfs("/sys/fs/cgroup", &st); err != nil {
-			isUnified, isUnifiedErr = false, err
-		} else {
-			isUnified, isUnifiedErr = st.Type == _cgroup2SuperMagic, nil
-		}
-	})
-	return isUnified, isUnifiedErr
-}
-
 // GetRootlessRuntimeDir returns the runtime directory when running as non root
 func GetRootlessRuntimeDir() (string, error) {
 	var rootlessRuntimeDirError error