ephemeral-storage: fix bind subcommand for multiple sequential calls

Fix bind subcommand to work when called multiple times in sequence
by checking if the mount point is already mounted before attempting
to mount the device.

Signed-off-by: Yutong Sun <[email protected]>

Author: ytsssun

sources/api/apiserver/src/server/ephemeral_storage.rs

@@ -129,8 +129,6 @@ pub fn bind(variant: &str, dirs: Vec<String>) -> Result<()> {
         .map(|dir| dir.trim_end_matches("/").to_string())
         .collect();
 
-    let mount_point = format!("/mnt/{EPHEMERAL_MNT}");
-    let mount_point = Path::new(&mount_point);
     let allowed_dirs = allowed_bind_dirs(variant);
     for dir in &dirs {
         let exact_match = allowed_dirs.allowed_exact.contains(dir.as_str());
@@ -150,26 +148,32 @@ pub fn bind(variant: &str, dirs: Vec<String>) -> Result<()> {
             }
         )
     }
-    std::fs::create_dir_all(mount_point).context(error::MkdirSnafu {})?;
 
-    info!("mounting {device_name:?} as {mount_point:?}");
-    let output = Command::new(MOUNT)
-        .args([
-            OsString::from(device_name.clone()),
-            OsString::from(mount_point.as_os_str()),
-        ])
-        .output()
-        .context(error::ExecutionFailureSnafu { command: MOUNT })?;
+    let mount_point = format!("/mnt/{EPHEMERAL_MNT}");
+    if !is_mounted(&mount_point)? {
+        std::fs::create_dir_all(&mount_point).context(error::MkdirSnafu {})?;
+        info!("mounting {device_name} as {mount_point}");
+        let output = Command::new(MOUNT)
+            .args([
+                OsString::from(device_name.clone()),
+                OsString::from(&mount_point),
+            ])
+            .output()
+            .context(error::ExecutionFailureSnafu { command: MOUNT })?;
 
-    ensure!(
-        output.status.success(),
-        error::MountArrayFailureSnafu {
-            what: device_name,
-            dest: mount_point.to_string_lossy().to_string(),
-            output
-        }
-    );
+        ensure!(
+            output.status.success(),
+            error::MountArrayFailureSnafu {
+                what: device_name,
+                dest: &mount_point,
+                output
+            }
+        );
+    } else {
+        info!("device already mounted at {mount_point}, skipping mount");
+    }
 
+    let mount_point = Path::new(&mount_point);
     for dir in &dirs {
         // construct a directory name (E.g. /var/lib/kubelet => ._var_lib_kubelet) that will be
         // unique between the binding targets