Support for hugetlbfs in empty dir volume plugin

pkg/api/types.go

@@ -681,8 +681,9 @@ type EmptyDirVolumeSource struct {
 type StorageMedium string
 
 const (
-	StorageMediumDefault StorageMedium = ""       // use whatever the default is for the node
-	StorageMediumMemory  StorageMedium = "Memory" // use memory (tmpfs)
+	StorageMediumDefault   StorageMedium = ""          // use whatever the default is for the node
+	StorageMediumMemory    StorageMedium = "Memory"    // use memory (tmpfs)
+	StorageMediumHugepages StorageMedium = "Hugepages" // use hugepages
 )
 
 // Protocol defines network protocols supported for things like container ports.

pkg/volume/empty_dir/empty_dir.go

@@ -104,9 +104,11 @@ func (plugin *emptyDirPlugin) NewMounter(spec *volume.Spec, pod *v1.Pod, opts vo
 
 func (plugin *emptyDirPlugin) newMounterInternal(spec *volume.Spec, pod *v1.Pod, mounter mount.Interface, mountDetector mountDetector, opts volume.VolumeOptions) (volume.Mounter, error) {
 	medium := v1.StorageMediumDefault
+
 	if spec.Volume.EmptyDir != nil { // Support a non-specified source as EmptyDir.
 		medium = spec.Volume.EmptyDir.Medium
 	}
+
 	return &emptyDir{
 		pod:             pod,
 		volName:         spec.Name(),
@@ -159,8 +161,9 @@ type mountDetector interface {
 type storageMedium int
 
 const (
-	mediumUnknown storageMedium = 0 // assume anything we don't explicitly handle is this
-	mediumMemory  storageMedium = 1 // memory (e.g. tmpfs on linux)
+	mediumUnknown   storageMedium = 0 // assume anything we don't explicitly handle is this
+	mediumMemory    storageMedium = 1 // memory (e.g. tmpfs on linux)
+	mediumHugepages storageMedium = 2 // hugepages
 )
 
 // EmptyDir volumes are temporary directories exposed to the pod.
@@ -221,6 +224,8 @@ func (ed *emptyDir) SetUpAt(dir string, fsGroup *int64) error {
 		err = ed.setupDir(dir)
 	case v1.StorageMediumMemory:
 		err = ed.setupTmpfs(dir)
+	case v1.StorageMediumHugepages:
+		err = ed.setupHugepages(dir)
 	default:
 		err = fmt.Errorf("unknown storage medium %q", ed.medium)
 	}
@@ -257,6 +262,29 @@ func (ed *emptyDir) setupTmpfs(dir string) error {
 	return ed.mounter.Mount("tmpfs", dir, "tmpfs", nil /* options */)
 }
 
+// setupHugepages creates a hugepage mount at the specified directory.
+func (ed *emptyDir) setupHugepages(dir string) error {
+	if ed.mounter == nil {
+		return fmt.Errorf("memory storage requested, but mounter is nil")
+	}
+	if err := ed.setupDir(dir); err != nil {
+		return err
+	}
+	// Make SetUp idempotent.
+	medium, isMnt, err := ed.mountDetector.GetMountMedium(dir)
+	if err != nil {
+		return err
+	}
+	// If the directory is a mountpoint with medium memory, there is no
+	// work to do since we are already in the desired state.
+	if isMnt && medium == mediumHugepages {
+		return nil
+	}
+
+	glog.V(3).Infof("pod %v: mounting hugepages for volume %v", ed.pod.UID, ed.volName)
+	return ed.mounter.Mount("nodev", dir, "hugetlbfs", []string{})
+}
+
 // setupDir creates the directory with the default permissions specified by the perm constant.
 func (ed *emptyDir) setupDir(dir string) error {
 	// Create the directory if it doesn't already exist.
@@ -318,9 +346,14 @@ func (ed *emptyDir) TearDownAt(dir string) error {
 	if err != nil {
 		return err
 	}
-	if isMnt && medium == mediumMemory {
-		ed.medium = v1.StorageMediumMemory
-		return ed.teardownTmpfs(dir)
+	if isMnt {
+		if medium == mediumMemory {
+			ed.medium = v1.StorageMediumMemory
+			return ed.teardownTmpfsOrHugetlbfs(dir)
+		} else if medium == mediumHugepages {
+			ed.medium = v1.StorageMediumHugepages
+			return ed.teardownTmpfsOrHugetlbfs(dir)
+		}
 	}
 	// assume StorageMediumDefault
 	return ed.teardownDefault(dir)
@@ -336,7 +369,7 @@ func (ed *emptyDir) teardownDefault(dir string) error {
 	return nil
 }
 
-func (ed *emptyDir) teardownTmpfs(dir string) error {
+func (ed *emptyDir) teardownTmpfsOrHugetlbfs(dir string) error {
 	if ed.mounter == nil {
 		return fmt.Errorf("memory storage requested, but mounter is nil")
 	}

pkg/volume/empty_dir/empty_dir_linux.go

@@ -27,7 +27,10 @@ import (
 )
 
 // Defined by Linux - the type number for tmpfs mounts.
-const linuxTmpfsMagic = 0x01021994
+const (
+	linuxTmpfsMagic     = 0x01021994
+	linuxHugetlbfsMagic = 0x958458f6
+)
 
 // realMountDetector implements mountDetector in terms of syscalls.
 type realMountDetector struct {
@@ -48,6 +51,8 @@ func (m *realMountDetector) GetMountMedium(path string) (storageMedium, bool, er
 	glog.V(5).Infof("Statfs_t of %v: %+v", path, buf)
 	if buf.Type == linuxTmpfsMagic {
 		return mediumMemory, !notMnt, nil
+	} else if buf.Type == linuxHugetlbfsMagic {
+		return mediumHugepages, !notMnt, nil
 	}
 	return mediumUnknown, !notMnt, nil
 }

pkg/volume/empty_dir/empty_dir_test.go

@@ -80,6 +80,15 @@ func TestPluginEmptyRootContext(t *testing.T) {
 		expectedTeardownMounts: 0})
 }
 
+func TestPluginHugetlbfs(t *testing.T) {
+	doTestPlugin(t, pluginTestConfig{
+		medium:                        v1.StorageMediumHugepages,
+		expectedSetupMounts:           1,
+		expectedTeardownMounts:        0,
+		shouldBeMountedBeforeTeardown: true,
+	})
+}
+
 type pluginTestConfig struct {
 	medium                        v1.StorageMedium
 	idempotent                    bool
@@ -165,7 +174,7 @@ func doTestPlugin(t *testing.T, config pluginTestConfig) {
 	if e, a := config.expectedSetupMounts, len(physicalMounter.Log); e != a {
 		t.Errorf("Expected %v physicalMounter calls during setup, got %v", e, a)
 	} else if config.expectedSetupMounts == 1 &&
-		(physicalMounter.Log[0].Action != mount.FakeActionMount || physicalMounter.Log[0].FSType != "tmpfs") {
+		(physicalMounter.Log[0].Action != mount.FakeActionMount || (physicalMounter.Log[0].FSType != "tmpfs" && physicalMounter.Log[0].FSType != "hugetlbfs")) {
 		t.Errorf("Unexpected physicalMounter action during setup: %#v", physicalMounter.Log[0])
 	}
 	physicalMounter.ResetLog()

staging/src/k8s.io/api/core/v1/types.go

@@ -943,8 +943,9 @@ type FlockerVolumeSource struct {
 type StorageMedium string
 
 const (
-	StorageMediumDefault StorageMedium = ""       // use whatever the default is for the node
-	StorageMediumMemory  StorageMedium = "Memory" // use memory (tmpfs)
+	StorageMediumDefault   StorageMedium = ""          // use whatever the default is for the node
+	StorageMediumMemory    StorageMedium = "Memory"    // use memory (tmpfs)
+	StorageMediumHugepages StorageMedium = "HugePages" // use hugepages
 )
 
 // Protocol defines network protocols supported for things like container ports.