Merge pull request #52401 from andyzhangx/azuredisk-getdevfunc

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

fix warning messages due to GetMountRefs func not implemented in windows

**What this PR does / why we need it**:
This PR completes the windows implementation of GetMountRefs in mount.go. In linux, the GetMountRefs implementaion is: read `/proc/mounts` and find all mount points, while in Windows, there is no such `/proc/mounts` place which shows all mounting points. 
There is another way in windows, **we could walk through(by `getAllParentLinks` func) the mount path(symbolic link) and get all symlinks until we got the final device, which is actually a drive**.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #54670
This PR fixed the warnning issue mentioned in https://github.com/kubernetes/kubernetes/pull/51252

**Special notes for your reviewer**:
Some values in the code would be like follwoing:
```
GetMountRefs: mountPath ("\\var\\lib\\kubelet\\pods/4c74b128-92ca-11e7-b86b-000d3a36d70c/volumes/kubernetes.io~azure-disk/pvc-1cc91c70-92ca-11e7-b86b-000d3a36d70c")
getAllParentLinks: refs (["" "" "c:\\var\\lib\\kubelet\\plugins\\kubernetes.io\\azure-disk\\mounts\\b1246717734" "G:\\"])
basemountPath c:\var\lib\kubelet\plugins\kubernetes.io\azure-disk\mounts
got volumeID b1246717734
```

**Release note**:

```
fix warning messages due to GetMountRefs func not implemented in windows
```

pkg/util/mount/mount_linux.go

@@ -22,6 +22,8 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"path"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"syscall"
@@ -141,6 +143,41 @@ func (m *Mounter) doMount(mounterPath string, mountCmd string, source string, ta
 	return err
 }
 
+// GetMountRefs finds all other references to the device referenced
+// by mountPath; returns a list of paths.
+func GetMountRefs(mounter Interface, mountPath string) ([]string, error) {
+	mps, err := mounter.List()
+	if err != nil {
+		return nil, err
+	}
+	// Find the device name.
+	deviceName := ""
+	// If mountPath is symlink, need get its target path.
+	slTarget, err := filepath.EvalSymlinks(mountPath)
+	if err != nil {
+		slTarget = mountPath
+	}
+	for i := range mps {
+		if mps[i].Path == slTarget {
+			deviceName = mps[i].Device
+			break
+		}
+	}
+
+	// Find all references to the device.
+	var refs []string
+	if deviceName == "" {
+		glog.Warningf("could not determine device for path: %q", mountPath)
+	} else {
+		for i := range mps {
+			if mps[i].Device == deviceName && mps[i].Path != slTarget {
+				refs = append(refs, mps[i].Path)
+			}
+		}
+	}
+	return refs, nil
+}
+
 // detectSystemd returns true if OS runs with systemd as init. When not sure
 // (permission errors, ...), it returns false.
 // There may be different ways how to detect systemd, this one makes sure that
@@ -299,6 +336,34 @@ func (mounter *Mounter) GetDeviceNameFromMount(mountPath, pluginDir string) (str
 	return getDeviceNameFromMount(mounter, mountPath, pluginDir)
 }
 
+// getDeviceNameFromMount find the device name from /proc/mounts in which
+// the mount path reference should match the given plugin directory. In case no mount path reference
+// matches, returns the volume name taken from its given mountPath
+func getDeviceNameFromMount(mounter Interface, mountPath, pluginDir string) (string, error) {
+	refs, err := GetMountRefs(mounter, mountPath)
+	if err != nil {
+		glog.V(4).Infof("GetMountRefs failed for mount path %q: %v", mountPath, err)
+		return "", err
+	}
+	if len(refs) == 0 {
+		glog.V(4).Infof("Directory %s is not mounted", mountPath)
+		return "", fmt.Errorf("directory %s is not mounted", mountPath)
+	}
+	basemountPath := path.Join(pluginDir, MountsInGlobalPDPath)
+	for _, ref := range refs {
+		if strings.HasPrefix(ref, basemountPath) {
+			volumeID, err := filepath.Rel(basemountPath, ref)
+			if err != nil {
+				glog.Errorf("Failed to get volume id from mount %s - %v", mountPath, err)
+				return "", err
+			}
+			return volumeID, nil
+		}
+	}
+
+	return path.Base(mountPath), nil
+}
+
 func listProcMounts(mountFilePath string) ([]MountPoint, error) {
 	content, err := utilio.ConsistentRead(mountFilePath, maxListTries)
 	if err != nil {