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Improve comments for volume path hanlder and volume.go

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This commit is contained in:
Masaki Kimura 2019-11-04 22:10:36 +00:00
parent 5a351e3014
commit 7abb704e7b
2 changed files with 27 additions and 5 deletions
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28
pkg/volume/util/volumepathhandler/volume_path_handler_linux.go
View File

@ -130,10 +130,14 @@ func parseLosetupOutputForDevice(output []byte, path string) (string, error) {
}
// losetup -j {path} returns device in the format:
// /dev/loop1: [0073]:148662 (/dev/{globalMapPath}/{pod1-UUID})
// /dev/loop2: [0073]:148662 (/dev/{globalMapPath}/{pod2-UUID})
// /dev/loop1: [0073]:148662 ({path})
// /dev/loop2: [0073]:148662 (/dev/sdX)
//
// losetup -j shows all the loop device for the same device that has the same
// major/minor number, by resolving symlink and matching major/minor number.
// Therefore, there will be other path than {path} in output, as shown in above output.
s := string(output)
// Find line that exact matches the path
// Find the line that exact matches to the path, or "({path})"
var matched string
scanner := bufio.NewScanner(strings.NewReader(s))
for scanner.Scan() {
@ -147,6 +151,8 @@ func parseLosetupOutputForDevice(output []byte, path string) (string, error) {
}
s = matched
// Get device name, or the 0th field of the output separated with ":".
// We don't need 1st field or later to be splitted, so passing 2 to SplitN.
device := strings.TrimSpace(strings.SplitN(s, ":", 2)[0])
if len(device) == 0 {
return "", errors.New(ErrDeviceNotFound)
@ -181,26 +187,42 @@ func (v VolumePathHandler) FindGlobalMapPathUUIDFromPod(pluginDir, mapPath strin
return globalMapPathUUID, nil
}
// compareBindMountAndSymlinks returns if global path (bind mount) and
// pod path (symlink) are pointing to the same device.
// If there is an error in checking it returns error.
func compareBindMountAndSymlinks(global, pod string) (bool, error) {
// To check if bind mount and symlink are pointing to the same device,
// we need to check if they are pointing to the devices that have same major/minor number.
// Get the major/minor number for global path
devNumGlobal, err := getDeviceMajorMinor(global)
if err != nil {
return false, err
}
// Get the symlinked device from the pod path
devPod, err := os.Readlink(pod)
if err != nil {
return false, err
}
// Get the major/minor number for the symlinked device from the pod path
devNumPod, err := getDeviceMajorMinor(devPod)
if err != nil {
return false, err
}
klog.V(5).Infof("CompareBindMountAndSymlinks: devNumGlobal %s, devNumPod %s", devNumGlobal, devNumPod)
// Check if the major/minor number are the same
if devNumGlobal == devNumPod {
return true, nil
}
return false, nil
}
// getDeviceMajorMinor returns major/minor number for the path with belwo format:
// major:minor (in hex)
// ex)
// fc:10
func getDeviceMajorMinor(path string) (string, error) {
args := []string{"-c", "%t:%T", path}
cmd := exec.Command(statPath, args...)

4
pkg/volume/volume.go
View File

@ -41,12 +41,12 @@ type Volume interface {
// and pod device map path.
type BlockVolume interface {
// GetGlobalMapPath returns a global map path which contains
// symbolic links associated to a block device.
// bind mount associated to a block device.
// ex. plugins/kubernetes.io/{PluginName}/{DefaultKubeletVolumeDevicesDirName}/{volumePluginDependentPath}/{pod uuid}
GetGlobalMapPath(spec *Spec) (string, error)
// GetPodDeviceMapPath returns a pod device map path
// and name of a symbolic link associated to a block device.
// ex. pods/{podUid}}/{DefaultKubeletVolumeDevicesDirName}/{escapeQualifiedPluginName}/{volumeName}
// ex. pods/{podUid}/{DefaultKubeletVolumeDevicesDirName}/{escapeQualifiedPluginName}/, {volumeName}
GetPodDeviceMapPath() (string, string)
}