From 37cdee17ee1afb94e73eaec485b8cec7051c58ed Mon Sep 17 00:00:00 2001
From: Jing Xu <jinxu@google.com>
Date: Mon, 18 May 2020 11:29:16 -0700
Subject: [PATCH] Remove driver letter assignment during volume format

This PR removes the driver letter assignment during volume format and
mount because driver letter might run out and cause issues during mount.
Intead, it uses volume id to mount the target dir.
---
 mount_windows.go | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/mount_windows.go b/mount_windows.go
index f8b5ca328a3..0534649c062 100644
--- a/mount_windows.go
+++ b/mount_windows.go
@@ -26,7 +26,6 @@ import (
 	"strings"
 
 	"k8s.io/klog/v2"
-	utilexec "k8s.io/utils/exec"
 	"k8s.io/utils/keymutex"
 )
 
@@ -222,17 +221,17 @@ func (mounter *SafeFormatAndMount) formatAndMountSensitive(source string, target
 
 	// format disk if it is unformatted(raw)
 	cmd := fmt.Sprintf("Get-Disk -Number %s | Where partitionstyle -eq 'raw' | Initialize-Disk -PartitionStyle MBR -PassThru"+
-		" | New-Partition -AssignDriveLetter -UseMaximumSize | Format-Volume -FileSystem %s -Confirm:$false", source, fstype)
+		" | New-Partition -UseMaximumSize | Format-Volume -FileSystem %s -Confirm:$false", source, fstype)
 	if output, err := mounter.Exec.Command("powershell", "/c", cmd).CombinedOutput(); err != nil {
 		return fmt.Errorf("diskMount: format disk failed, error: %v, output: %q", err, string(output))
 	}
 	klog.V(4).Infof("diskMount: Disk successfully formatted, disk: %q, fstype: %q", source, fstype)
 
-	driveLetter, err := getDriveLetterByDiskNumber(source, mounter.Exec)
+	volumeIds, err := listVolumesOnDisk(source)
 	if err != nil {
 		return err
 	}
-	driverPath := driveLetter + ":"
+	driverPath := volumeIds[0]
 	target = NormalizeWindowsPath(target)
 	output, err := mounter.Exec.Command("cmd", "/c", "mklink", "/D", target, driverPath).CombinedOutput()
 	if err != nil {
@@ -243,17 +242,17 @@ func (mounter *SafeFormatAndMount) formatAndMountSensitive(source string, target
 	return nil
 }
 
-// Get drive letter according to windows disk number
-func getDriveLetterByDiskNumber(diskNum string, exec utilexec.Interface) (string, error) {
-	cmd := fmt.Sprintf("(Get-Partition -DiskNumber %s).DriveLetter", diskNum)
+// ListVolumesOnDisk - returns back list of volumes(volumeIDs) in the disk (requested in diskID).
+func listVolumesOnDisk(diskID string) (volumeIDs []string, err error) {
+	cmd := fmt.Sprintf("(Get-Disk -DeviceId %s | Get-Partition | Get-Volume).UniqueId", diskID)
 	output, err := exec.Command("powershell", "/c", cmd).CombinedOutput()
+	klog.V(4).Infof("listVolumesOnDisk id from %s: %s", diskID, string(output))
 	if err != nil {
-		return "", fmt.Errorf("azureMount: Get Drive Letter failed: %v, output: %q", err, string(output))
+		return []string{}, fmt.Errorf("error list volumes on disk. cmd: %s, output: %s, error: %v", cmd, string(output), err)
 	}
-	if len(string(output)) < 1 {
-		return "", fmt.Errorf("azureMount: Get Drive Letter failed, output is empty")
-	}
-	return string(output)[:1], nil
+
+	volumeIds := strings.Split(strings.TrimSpace(string(output)), "\r\n")
+	return volumeIds, nil
 }
 
 // getAllParentLinks walks all symbolic links and return all the parent targets recursively