empty_dir: Check if hugetlbfs volume is mounted with a correct pagesize

Extended GetMountMedium function to check if hugetlbfs volume
is mounted with the page size equal to the medium size.

Page size is obtained from the 'pagesize' mount option of the
mounted hugetlbfs volume.

pkg/volume/emptydir/empty_dir_linux.go

@@ -20,12 +20,14 @@ package emptydir
 
 import (
 	"fmt"
+	"strings"
 
 	"golang.org/x/sys/unix"
+	"k8s.io/apimachinery/pkg/api/resource"
 	"k8s.io/klog"
 	"k8s.io/utils/mount"
 
-	v1 "k8s.io/api/core/v1"
+	"k8s.io/api/core/v1"
 )
 
 // Defined by Linux - the type number for tmpfs mounts.
@@ -39,22 +41,71 @@ type realMountDetector struct {
 	mounter mount.Interface
 }
 
-func (m *realMountDetector) GetMountMedium(path string) (v1.StorageMedium, bool, error) {
+// getPageSize obtains page size from the 'pagesize' mount option of the
+// mounted volume
+func getPageSize(path string, mounter mount.Interface) (*resource.Quantity, error) {
+	// Get mount point data for the path
+	mountPoints, err := mounter.List()
+	if err != nil {
+		return nil, fmt.Errorf("error listing mount points: %v", err)
+	}
+	// Find mount point for the path
+	mountPoint, err := func(mps []mount.MountPoint, mpPath string) (*mount.MountPoint, error) {
+		for _, mp := range mps {
+			if mp.Path == mpPath {
+				return &mp, nil
+			}
+		}
+		return nil, fmt.Errorf("mount point for %s not found", mpPath)
+	}(mountPoints, path)
+	if err != nil {
+		return nil, err
+	}
+	// Get page size from the 'pagesize' option value
+	for _, opt := range mountPoint.Opts {
+		opt = strings.TrimSpace(opt)
+		prefix := "pagesize="
+		if strings.HasPrefix(opt, prefix) {
+			// NOTE: Adding suffix 'i' as result should be comparable with a medium size.
+			// pagesize mount option is specified without a suffix,
+			// e.g. pagesize=2M or pagesize=1024M for x86 CPUs
+			pageSize, err := resource.ParseQuantity(strings.TrimPrefix(opt, prefix) + "i")
+			if err != nil {
+				return nil, fmt.Errorf("error getting page size from '%s' mount option: %v", opt, err)
+			}
+			return &pageSize, nil
+		}
+	}
+	return nil, fmt.Errorf("no pagesize option specified for %s mount", mountPoint.Path)
+}
+
+func (m *realMountDetector) GetMountMedium(path string, requestedMedium v1.StorageMedium) (v1.StorageMedium, bool, *resource.Quantity, error) {
 	klog.V(5).Infof("Determining mount medium of %v", path)
 	notMnt, err := m.mounter.IsLikelyNotMountPoint(path)
 	if err != nil {
-		return v1.StorageMediumDefault, false, fmt.Errorf("IsLikelyNotMountPoint(%q): %v", path, err)
-	}
-	buf := unix.Statfs_t{}
-	if err := unix.Statfs(path, &buf); err != nil {
-		return v1.StorageMediumDefault, false, fmt.Errorf("statfs(%q): %v", path, err)
+		return v1.StorageMediumDefault, false, nil, fmt.Errorf("IsLikelyNotMountPoint(%q): %v", path, err)
 	}
 
-	klog.V(5).Infof("Statfs_t of %v: %+v", path, buf)
-	if buf.Type == linuxTmpfsMagic {
-		return v1.StorageMediumMemory, !notMnt, nil
-	} else if int64(buf.Type) == linuxHugetlbfsMagic {
-		return v1.StorageMediumHugePages, !notMnt, nil
+	buf := unix.Statfs_t{}
+	if err := unix.Statfs(path, &buf); err != nil {
+		return v1.StorageMediumDefault, false, nil, fmt.Errorf("statfs(%q): %v", path, err)
 	}
-	return v1.StorageMediumDefault, !notMnt, nil
+
+	klog.V(3).Infof("Statfs_t of %v: %+v", path, buf)
+
+	if buf.Type == linuxTmpfsMagic {
+		return v1.StorageMediumMemory, !notMnt, nil, nil
+	} else if int64(buf.Type) == linuxHugetlbfsMagic {
+		// Skip page size detection if requested medium doesn't have size specified
+		if requestedMedium == v1.StorageMediumHugePages {
+			return v1.StorageMediumHugePages, !notMnt, nil, nil
+		}
+		// Get page size for the volume mount
+		pageSize, err := getPageSize(path, m.mounter)
+		if err != nil {
+			return v1.StorageMediumHugePages, !notMnt, nil, err
+		}
+		return v1.StorageMediumHugePages, !notMnt, pageSize, nil
+	}
+	return v1.StorageMediumDefault, !notMnt, nil, nil
 }