Do not clean tempdir if we fail to unmount

Ran into this issue by chance in bootupd where a the following drop ordering

```rust
drop(tempdir)
drop(mount) // unmounts thing mounted at tempdir
```

was causing all the contents of the mounted device to be deleted because
the tempdir was being deleted. We might run into the same issue with our
Tempdir impl if we fail to unount the ESP and tempdir is dropped
deleting everything the ESP.

To preven that, explicitly set `disable_cleanup` to false on the Tempdir
and only enable cleanup after we've successfully unmounted whatever was
mounted

Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Author: Johan-Liebert1

crates/mount/src/tempmount.rs

@@ -67,7 +67,8 @@ impl TempMount {
         flags: MountFlags,
         data: Option<&std::ffi::CStr>,
     ) -> Result<Self> {
-        let tempdir = tempfile::TempDir::new()?;
+        let mut tempdir = tempfile::TempDir::new()?;
+        tempdir.disable_cleanup(true);
 
         let utf8path = Utf8Path::from_path(tempdir.path())
             .ok_or(anyhow::anyhow!("Failed to convert path to UTF-8 Path"))?;
@@ -81,7 +82,8 @@ impl TempMount {
             Ok(fd) => fd,
             Err(e) => {
                 unmount(tempdir.path(), UnmountFlags::DETACH)?;
-                Err(e)?
+                tempdir.disable_cleanup(false);
+                return Err(e)?;
             }
         };
 
@@ -91,7 +93,8 @@ impl TempMount {
     /// Mount and fd acquired with `open_tree` like syscall
     #[context("Mounting fd")]
     pub fn mount_fd(mnt_fd: impl AsFd) -> Result<Self> {
-        let tempdir = tempfile::TempDir::new()?;
+        let mut tempdir = tempfile::TempDir::new()?;
+        tempdir.disable_cleanup(true);
 
         move_mount(
             mnt_fd.as_fd(),
@@ -109,7 +112,8 @@ impl TempMount {
             Ok(fd) => fd,
             Err(e) => {
                 unmount(tempdir.path(), UnmountFlags::DETACH)?;
-                Err(e)?
+                tempdir.disable_cleanup(false);
+                return Err(e)?;
             }
         };
 
@@ -120,7 +124,9 @@ impl TempMount {
 impl Drop for TempMount {
     fn drop(&mut self) {
         match unmount(self.dir.path(), UnmountFlags::DETACH) {
-            Ok(_) => {}
+            Ok(_) => self.dir.disable_cleanup(false),
+            // DO NOT clean the tempdir if we fail to unmount
+            // else it would delete the entire ESP
             Err(e) => tracing::warn!("Failed to unmount tempdir: {e:?}"),
         }
     }