actions/image-partition: add optional argument filesystem label

Add optional argument filesystem label which defaults to partiton name
and is used in mkfs commands.

Fixes: go-debos#251

Suggested-by: Christopher Obbard <chris.obbard@collabora.com>
Signed-off-by: Vignesh Raman <vignesh.raman@collabora.com>

actions/image_partition_action.go

@@ -43,6 +43,7 @@ Yaml syntax for partitions:
      - name: partition name
 	   partlabel: partition label
 	   fs: filesystem
+	   fslabel: filesystem label
 	   start: offset
 	   end: offset
 	   features: list of filesystem features
@@ -72,6 +73,11 @@ Optional properties:
 - partlabel -- label for the partition in the GPT partition table. Defaults
 to the `name` property of the partition. May only be used for GPT partitions.
 
+- fslabel -- Sets  the  volume name (label) of the filesystem. Defaults to the
+`name` property of the partition. The filesystem label can be up to 11 characters
+long for vfat, 16 characters long for ext2/3/4, 255 characters long for btrfs,
+512 characters long for hfs/hfsplus and 12 characters long for xfs.
+
 - parttype -- set the partition type in the partition table. The string should
 be in a hexadecimal format (2-characters) for msdos partition tables and GUID format
 (36-characters) for GPT partition tables. For instance, "82" for msdos sets the
@@ -168,6 +174,7 @@ type Partition struct {
 	number    int
 	Name      string
 	PartLabel string
+	FSLabel   string
 	PartType  string
 	Start     string
 	End       string
@@ -305,37 +312,37 @@ func (i ImagePartitionAction) formatPartition(p *Partition, context debos.DebosC
 	cmdline := []string{}
 	switch p.FS {
 	case "vfat":
-		cmdline = append(cmdline, "mkfs.vfat", "-F32", "-n", p.Name)
+		cmdline = append(cmdline, "mkfs.vfat", "-F32", "-n", p.FSLabel)
 	case "btrfs":
 		// Force formatting to prevent failure in case if partition was formatted already
-		cmdline = append(cmdline, "mkfs.btrfs", "-L", p.Name, "-f")
+		cmdline = append(cmdline, "mkfs.btrfs", "-L", p.FSLabel, "-f")
 		if len(p.Features) > 0 {
 			cmdline = append(cmdline, "-O", strings.Join(p.Features, ","))
 		}
 		if len(p.FSUUID) > 0 {
 			cmdline = append(cmdline, "-U", p.FSUUID)
 		}
 	case "f2fs":
-		cmdline = append(cmdline, "mkfs.f2fs", "-l", p.Name)
+		cmdline = append(cmdline, "mkfs.f2fs", "-l", p.FSLabel)
 		if len(p.Features) > 0 {
 			cmdline = append(cmdline, "-O", strings.Join(p.Features, ","))
 		}
 	case "hfs":
-		cmdline = append(cmdline, "mkfs.hfs", "-h", "-v", p.Name)
+		cmdline = append(cmdline, "mkfs.hfs", "-h", "-v", p.FSLabel)
 	case "hfsplus":
-		cmdline = append(cmdline, "mkfs.hfsplus", "-v", p.Name)
+		cmdline = append(cmdline, "mkfs.hfsplus", "-v", p.FSLabel)
 	case "hfsx":
-		cmdline = append(cmdline, "mkfs.hfsplus", "-s", "-v", p.Name)
+		cmdline = append(cmdline, "mkfs.hfsplus", "-s", "-v", p.FSLabel)
 		// hfsx is case-insensitive hfs+, should be treated as "normal" hfs+ from now on
 		p.FS = "hfsplus"
 	case "xfs":
-		cmdline = append(cmdline, "mkfs.xfs", "-L", p.Name)
+		cmdline = append(cmdline, "mkfs.xfs", "-L", p.FSLabel)
 		if len(p.FSUUID) > 0 {
 			cmdline = append(cmdline, "-m", "uuid="+p.FSUUID)
 		}
 	case "none":
 	default:
-		cmdline = append(cmdline, fmt.Sprintf("mkfs.%s", p.FS), "-L", p.Name)
+		cmdline = append(cmdline, fmt.Sprintf("mkfs.%s", p.FS), "-L", p.FSLabel)
 		if len(p.Features) > 0 {
 			cmdline = append(cmdline, "-O", strings.Join(p.Features, ","))
 		}
@@ -613,6 +620,12 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 			}
 		}
 
+		if i.PartitionType == "gpt" {
+			if p.FSLabel == "" {
+				p.FSLabel = p.Name
+			}
+		}
+
 		if len(p.FSUUID) > 0 {
 			if p.FS == "btrfs" || p.FS == "ext2" || p.FS == "ext3" || p.FS == "ext4" || p.FS == "xfs" {
 				_, err := uuid.Parse(p.FSUUID)