blockdev: Add maj_min filed in Device

This patch introduces a new field in the Device struct
for major and minor device numbers.

Signed-off-by: Yohei Ueda <yohei@jp.ibm.com>

lib/src/blockdev.rs

@@ -31,6 +31,8 @@ pub(crate) struct Device {
     pub(crate) fstype: Option<String>,
     pub(crate) children: Option<Vec<Device>>,
     pub(crate) size: Option<String>,
+    #[serde(rename = "maj:min")]
+    pub(crate) maj_min: Option<String>,
 }
 
 impl Device {
@@ -56,7 +58,7 @@ pub(crate) fn wipefs(dev: &Utf8Path) -> Result<()> {
 
 fn list_impl(dev: Option<&Utf8Path>) -> Result<Vec<Device>> {
     let o = Command::new("lsblk")
-        .args(["-J", "-o", "NAME,SERIAL,MODEL,LABEL,FSTYPE,SIZE"])
+        .args(["-J", "-o", "NAME,SERIAL,MODEL,LABEL,FSTYPE,SIZE,MAJ:MIN"])
         .args(dev)
         .output()?;
     if !o.status.success() {