install: mount esp in clean_boot_directories()

On FCOS, esp is not mounted after booted, need to find esp and
mount before cleaning, or `/boot/efi` will be removed.

Signed-off-by: Huijing Hei <hhei@redhat.com>

Author: HuijingHei

crates/lib/src/bootloader.rs

@@ -5,12 +5,13 @@ use anyhow::{anyhow, bail, Context, Result};
 use bootc_utils::CommandRunExt;
 use camino::Utf8Path;
 use cap_std_ext::cap_std::fs::Dir;
+use cap_std_ext::dirext::CapStdExtDirExt;
 use fn_error_context::context;
 
 use bootc_blockdev::{Partition, PartitionTable};
 use bootc_mount as mount;
 
-use crate::bootc_composefs::boot::{mount_esp, SecurebootKeys};
+use crate::bootc_composefs::boot::{get_sysroot_parent_dev, mount_esp, SecurebootKeys};
 use crate::{discoverable_partition_specification, utils};
 
 /// The name of the mountpoint for efi (as a subdirectory of /boot, or at the toplevel)
@@ -30,6 +31,42 @@ pub(crate) fn esp_in(device: &PartitionTable) -> Result<&Partition> {
         .ok_or(anyhow::anyhow!("ESP not found in partition table"))
 }
 
+/// Get esp partition node based on the root dir
+pub(crate) fn get_esp_partition_node(root: &Dir) -> Result<Option<String>> {
+    let device = get_sysroot_parent_dev(&root)?;
+    let base_partitions = bootc_blockdev::partitions_of(Utf8Path::new(&device))?;
+    let esp = base_partitions.find_partition_of_esp()?;
+    Ok(esp.map(|v| v.node.clone()))
+}
+
+/// Mount ESP part at /boot/efi
+pub(crate) fn mount_esp_part(root: &Dir, root_path: &Utf8Path, is_ostree: bool) -> Result<()> {
+    let efi_path = Utf8Path::new("boot").join(crate::bootloader::EFI_DIR);
+    let Some(esp_fd) = root
+        .open_dir_optional(&efi_path)
+        .context("Opening /boot/efi")?
+    else {
+        return Ok(());
+    };
+
+    let Some(false) = esp_fd.is_mountpoint(".")? else {
+        return Ok(());
+    };
+
+    tracing::debug!("Not a mountpoint: /boot/efi");
+    // On ostree env with enabled composefs, should be /target/sysroot
+    let physical_root = if is_ostree {
+        &root.open_dir("sysroot").context("Opening /sysroot")?
+    } else {
+        root
+    };
+    if let Some(esp_part) = get_esp_partition_node(physical_root)? {
+        bootc_mount::mount(&esp_part, &root_path.join(&efi_path))?;
+        tracing::debug!("Mounted {esp_part} at /boot/efi");
+    }
+    Ok(())
+}
+
 /// Determine if the invoking environment contains bootupd, and if there are bootupd-based
 /// updates in the target root.
 #[context("Querying for bootupd")]

crates/lib/src/install.rs

@@ -1980,15 +1980,20 @@ fn remove_all_except_loader_dirs(bootdir: &Dir, is_ostree: bool) -> Result<()> {
 }
 
 #[context("Removing boot directory content")]
-fn clean_boot_directories(rootfs: &Dir, is_ostree: bool) -> Result<()> {
+fn clean_boot_directories(rootfs: &Dir, rootfs_path: &Utf8Path, is_ostree: bool) -> Result<()> {
     let bootdir =
         crate::utils::open_dir_remount_rw(rootfs, BOOT.into()).context("Opening /boot")?;
 
+    if ARCH_USES_EFI {
+        // On booted FCOS, esp is not mounted by default
+        // Mount ESP part at /boot/efi before clean
+        crate::bootloader::mount_esp_part(&rootfs, &rootfs_path, is_ostree)?;
+    }
+
     // This should not remove /boot/efi note.
     remove_all_except_loader_dirs(&bootdir, is_ostree).context("Emptying /boot")?;
 
-    // TODO: Discover the ESP the same way bootupd does it; we should also
-    // support not wiping the ESP.
+    // TODO: we should also support not wiping the ESP.
     if ARCH_USES_EFI {
         if let Some(efidir) = bootdir
             .open_dir_optional(crate::bootloader::EFI_DIR)
@@ -2196,7 +2201,7 @@ pub(crate) async fn install_to_filesystem(
                 .await??;
         }
         Some(ReplaceMode::Alongside) => {
-            clean_boot_directories(&target_rootfs_fd, is_already_ostree)?
+            clean_boot_directories(&target_rootfs_fd, &target_root_path, is_already_ostree)?
         }
         None => require_empty_rootdir(&rootfs_fd)?,
     }