efi: Rework mount order

This ensures that we'll use `/boot/efi` first, which is what
is more commonly expected in our current ecosystem.

src/efi.rs

@@ -20,7 +20,7 @@ use crate::util::CommandRunExt;
 use crate::{component::*, packagesystem};
 
 /// Well-known paths to the ESP that may have been mounted external to us.
-pub(crate) const ESP_MOUNTS: &[&str] = &["boot", "boot/efi", "efi"];
+pub(crate) const ESP_MOUNTS: &[&str] = &["boot/efi", "efi", "boot"];
 
 /// The ESP partition label on Fedora CoreOS derivatives
 pub(crate) const COREOS_ESP_PART_LABEL: &str = "EFI-SYSTEM";
@@ -54,7 +54,7 @@ impl Efi {
  Ok(esp)
  }
 
- fn ensure_mounted_esp(&self, root: &Path) -> Result<PathBuf> {
+ pub(crate) fn ensure_mounted_esp(&self, root: &Path) -> Result<PathBuf> {
  let mut mountpoint = self.mountpoint.borrow_mut();
  if let Some(mountpoint) = mountpoint.as_deref() {
  return Ok(mountpoint.to_owned());
@@ -84,16 +84,22 @@ impl Efi {
  }
  }
  let esp_device = esp_device.ok_or_else(|| anyhow::anyhow!("Failed to find ESP device"))?;
- let tmppath = tempfile::tempdir_in("/tmp")?.into_path();
- let status = std::process::Command::new("mount")
- .arg(&esp_device)
- .arg(&tmppath)
- .status()?;
- if !status.success() {
- anyhow::bail!("Failed to mount {:?}", esp_device);
+ for &mnt in ESP_MOUNTS.iter() {
+ let mnt = root.join(mnt);
+ if !mnt.exists() {
+ continue;
+ }
+ let status = std::process::Command::new("mount")
+ .arg(&esp_device)
+ .arg(&mnt)
+ .status()?;
+ if !status.success() {
+ anyhow::bail!("Failed to mount {:?}", esp_device);
+ }
+ log::debug!("Mounted at {mnt:?}");
+ *mountpoint = Some(mnt);
+ break;
  }
- log::debug!("Mounted at {tmppath:?}");
- *mountpoint = Some(tmppath);
  Ok(mountpoint.as_deref().unwrap().to_owned())
  }
 
@@ -380,6 +386,7 @@ impl Component for Efi {
 
 impl Drop for Efi {
  fn drop(&mut self) {
+ log::debug!("Unmounting");
  let _ = self.unmount();
  }
 }