Parse mount options with double quotes and commas correctly

A mount option can contain commas in double quoted string. Such comma is
part of the mount option and it is not option separator.

For example, this is a single mount option:
  context="system_u:object_r:container_file_t:s0:c460,c902"

staging/src/k8s.io/mount-utils/mount_helper_unix.go

@@ -136,7 +136,7 @@ func ParseMountInfo(filename string) ([]MountInfo, error) {
 			Minor:        minor,
 			Root:         fields[3],
 			MountPoint:   fields[4],
-			MountOptions: strings.Split(fields[5], ","),
+			MountOptions: splitMountOptions(fields[5]),
 		}
 		// All fields until "-" are "optional fields".
 		i := 6
@@ -150,12 +150,26 @@ func ParseMountInfo(filename string) ([]MountInfo, error) {
 		}
 		info.FsType = fields[i]
 		info.Source = fields[i+1]
-		info.SuperOptions = strings.Split(fields[i+2], ",")
+		info.SuperOptions = splitMountOptions(fields[i+2])
 		infos = append(infos, info)
 	}
 	return infos, nil
 }
 
+// splitMountOptions parses comma-separated list of mount options into an array.
+// It respects double quotes - commas in them are not considered as the option separator.
+func splitMountOptions(s string) []string {
+	inQuotes := false
+	list := strings.FieldsFunc(s, func(r rune) bool {
+		if r == '"' {
+			inQuotes = !inQuotes
+		}
+		// Report a new field only when outside of double quotes.
+		return r == ',' && !inQuotes
+	})
+	return list
+}
+
 // isMountPointMatch returns true if the path in mp is the same as dir.
 // Handles case where mountpoint dir has been renamed due to stale NFS mount.
 func isMountPointMatch(mp MountPoint, dir string) bool {

staging/src/k8s.io/mount-utils/mount_helper_unix_test.go

@@ -83,6 +83,7 @@ func TestParseMountInfo(t *testing.T) {
 38 28 0:34 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime shared:20 - cgroup cgroup rw,blkio
 39 28 0:35 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,memory
 40 28 0:36 / /sys/fs/cgroup/perf_event rw,nosuid,nodev,noexec,relatime shared:22 - cgroup cgroup rw,perf_event
+761 60 8:0 / /var/lib/kubelet/plugins/kubernetes.io/iscsi/iface-default/127.0.0.1:3260-iqn.2003-01.org.linux-iscsi.f21.x8664:sn.4b0aae584f7c-lun-0 rw,relatime shared:421 - ext4 /dev/sda rw,context="system_u:object_r:container_file_t:s0:c314,c894",data=ordered
 `
 	tempDir, filename, err := writeFile(info)
 	if err != nil {
@@ -197,6 +198,23 @@ func TestParseMountInfo(t *testing.T) {
 				SuperOptions:   []string{"rw", "cpuset"},
 			},
 		},
+		{
+			"mount option with commas inside quotes",
+			761,
+			MountInfo{
+				ID:             761,
+				ParentID:       60,
+				Major:          8,
+				Minor:          0,
+				Root:           "/",
+				Source:         "/dev/sda",
+				MountPoint:     "/var/lib/kubelet/plugins/kubernetes.io/iscsi/iface-default/127.0.0.1:3260-iqn.2003-01.org.linux-iscsi.f21.x8664:sn.4b0aae584f7c-lun-0",
+				OptionalFields: []string{"shared:421"},
+				FsType:         "ext4",
+				MountOptions:   []string{"rw", "relatime"},
+				SuperOptions:   []string{"rw", "context=\"system_u:object_r:container_file_t:s0:c314,c894\"", "data=ordered"},
+			},
+		},
 	}
 
 	infos, err := ParseMountInfo(filename)