Merge pull request #2775 from gjkim42/0.38-backport-2752

Cherrypick to v0.38: Return correct DeviceInfo from GetDirFsDevice on / path for Btrfs - Fix kubernetes issue #94335

fs/fs.go

@@ -527,22 +527,7 @@ func (i *RealFsInfo) GetDeviceInfoByFsUUID(uuid string) (*DeviceInfo, error) {
 	return &DeviceInfo{deviceName, p.major, p.minor}, nil
 }
 
-func (i *RealFsInfo) GetDirFsDevice(dir string) (*DeviceInfo, error) {
-	buf := new(syscall.Stat_t)
-	err := syscall.Stat(dir, buf)
-	if err != nil {
-		return nil, fmt.Errorf("stat failed on %s with error: %s", dir, err)
-	}
-
-	// The type Dev in Stat_t is 32bit on mips.
-	major := major(uint64(buf.Dev)) // nolint: unconvert
-	minor := minor(uint64(buf.Dev)) // nolint: unconvert
-	for device, partition := range i.partitions {
-		if partition.major == major && partition.minor == minor {
-			return &DeviceInfo{device, major, minor}, nil
-		}
-	}
-
+func (i *RealFsInfo) mountInfoFromDir(dir string) (*mount.MountInfo, bool) {
 	mount, found := i.mounts[dir]
 	// try the parent dir if not found until we reach the root dir
 	// this is an issue on btrfs systems where the directory is not
@@ -551,16 +536,36 @@ func (i *RealFsInfo) GetDirFsDevice(dir string) (*DeviceInfo, error) {
 		pathdir, _ := filepath.Split(dir)
 		// break when we reach root
 		if pathdir == "/" {
+			mount, found = i.mounts["/"]
 			break
 		}
 		// trim "/" from the new parent path otherwise the next possible
 		// filepath.Split in the loop will not split the string any further
 		dir = strings.TrimSuffix(pathdir, "/")
 		mount, found = i.mounts[dir]
 	}
+	return &mount, found
+}
+
+func (i *RealFsInfo) GetDirFsDevice(dir string) (*DeviceInfo, error) {
+	buf := new(syscall.Stat_t)
+	err := syscall.Stat(dir, buf)
+	if err != nil {
+		return nil, fmt.Errorf("stat failed on %s with error: %s", dir, err)
+	}
+
+	// The type Dev in Stat_t is 32bit on mips.
+	major := major(uint64(buf.Dev)) // nolint: unconvert
+	minor := minor(uint64(buf.Dev)) // nolint: unconvert
+	for device, partition := range i.partitions {
+		if partition.major == major && partition.minor == minor {
+			return &DeviceInfo{device, major, minor}, nil
+		}
+	}
 
+	mount, found := i.mountInfoFromDir(dir)
 	if found && mount.FsType == "btrfs" && mount.Major == 0 && strings.HasPrefix(mount.Source, "/dev/") {
-		major, minor, err := getBtrfsMajorMinorIds(&mount)
+		major, minor, err := getBtrfsMajorMinorIds(mount)
 		if err != nil {
 			klog.Warningf("%s", err)
 		} else {

fs/fs_test.go

@@ -27,6 +27,20 @@ import (
 	"k8s.io/utils/mount"
 )
 
+func TestMountInfoFromDir(t *testing.T) {
+	as := assert.New(t)
+	fsInfo := &RealFsInfo{
+		mounts: map[string]mount.MountInfo{
+			"/": {},
+		},
+	}
+	testDirs := []string{"/var/lib/kubelet", "/var/lib/rancher"}
+	for _, testDir := range testDirs {
+		_, found := fsInfo.mountInfoFromDir(testDir)
+		as.True(found, "failed to find MountInfo %s from FsInfo %s", testDir, fsInfo)
+	}
+}
+
 func TestGetDiskStatsMap(t *testing.T) {
 	diskStatsMap, err := getDiskStatsMap("test_resources/diskstats")
 	if err != nil {