store kernel/initrd in rootfs

Author: p5

crates/lib/src/install.rs

@@ -1633,47 +1633,49 @@ fn find_vmlinuz_initrd_duplicates(digest: &str) -> Result<Option<String>> {
     Ok(symlink_to)
 }
 
-#[context("Writing BLS entries to disk")]
-fn write_bls_boot_entries_to_disk(
-    boot_dir: &Utf8PathBuf,
+/// Write vmlinuz and initrd to the rootfs boot directory
+#[context("Writing vmlinuz/initrd to rootfs")]
+fn write_vmlinuz_initrd_to_rootfs(
+    rootfs_boot_dir: &Utf8PathBuf,
     deployment_id: &Sha256HashValue,
     entry: &UsrLibModulesVmlinuz<Sha256HashValue>,
     repo: &ComposefsRepository<Sha256HashValue>,
 ) -> Result<()> {
     let id_hex = deployment_id.to_hex();
-
-    // Write the initrd and vmlinuz at /boot/<id>/
-    let path = boot_dir.join(&id_hex);
+    let path = rootfs_boot_dir.join(&id_hex);
     create_dir_all(&path)?;
-
-    let entries_dir = cap_std::fs::Dir::open_ambient_dir(&path, cap_std::ambient_authority())
+    let dir = cap_std::fs::Dir::open_ambient_dir(&path, cap_std::ambient_authority())
         .with_context(|| format!("Opening {path}"))?;
-
-    entries_dir
-        .atomic_write(
-            "vmlinuz",
-            read_file(&entry.vmlinuz, &repo).context("Reading vmlinuz")?,
-        )
-        .context("Writing vmlinuz to path")?;
-
+    dir.atomic_write(
+        "vmlinuz",
+        read_file(&entry.vmlinuz, &repo).context("Reading vmlinuz")?,
+    ).context("Writing vmlinuz to rootfs")?;
     let Some(initramfs) = &entry.initramfs else {
         anyhow::bail!("initramfs not found");
     };
+    dir.atomic_write(
+        "initrd",
+        read_file(initramfs, &repo).context("Reading initrd")?,
+    ).context("Writing initrd to rootfs")?;
+    let owned_fd = dir.reopen_as_ownedfd().context("Reopen as owned fd")?;
+    rustix::fs::fsync(owned_fd).context("fsync rootfs boot dir")?;
+    Ok(())
+}
 
-    entries_dir
-        .atomic_write(
-            "initrd",
-            read_file(initramfs, &repo).context("Reading initrd")?,
-        )
-        .context("Writing initrd to path")?;
-
-    // Can't call fsync on O_PATH fds, so re-open it as a non O_PATH fd
-    let owned_fd = entries_dir
-        .reopen_as_ownedfd()
-        .context("Reopen as owned fd")?;
-
-    rustix::fs::fsync(owned_fd).context("fsync")?;
-
+/// Write BLS entry to ESP, referencing vmlinuz/initrd in rootfs
+#[context("Writing BLS entry to ESP")]
+fn write_bls_entry_to_esp(
+    esp_dir: &Utf8PathBuf,
+    bls_config: &BLSConfig,
+) -> Result<()> {
+    let entries_dir = cap_std::fs::Dir::open_ambient_dir(esp_dir, cap_std::ambient_authority())
+        .with_context(|| format!("Opening {esp_dir}"))?;
+    entries_dir.atomic_write(
+        format!("bootc-composefs-{}.conf", bls_config.sort_key.as_ref().unwrap()),
+        bls_config.to_string().as_bytes(),
+    )?;
+    let owned_fd = entries_dir.reopen_as_ownedfd().context("Reopen as owned fd")?;
+    rustix::fs::fsync(owned_fd).context("fsync ESP dir")?;
     Ok(())
 }
 
@@ -1768,18 +1770,22 @@ pub(crate) fn setup_composefs_bls_boot(
             bls_config.title = Some(id_hex.clone());
             bls_config.sort_key = Some("1".into());
             bls_config.machine_id = None;
-            bls_config.linux = format!("/EFI/Linux/{id_hex}/vmlinuz");
-            bls_config.initrd = vec![format!("/EFI/Linux/{id_hex}/initrd")];
+            bls_config.linux = format!("/boot/{id_hex}/vmlinuz");
+            bls_config.initrd = vec![format!("/boot/{id_hex}/initrd")];
             bls_config.options = Some(cmdline_refs);
             bls_config.extra = HashMap::new();
 
             if let Some(symlink_to) = find_vmlinuz_initrd_duplicates(&boot_digest)? {
                 bls_config.linux = format!("/EFI/Linux/{symlink_to}/vmlinuz");
                 bls_config.initrd = vec![format!("/EFI/Linux/{symlink_to}/initrd")];
             } else {
+                // Write vmlinuz/initrd to rootfs boot dir
+                let rootfs_boot_dir = root_path.join("boot");
+                write_vmlinuz_initrd_to_rootfs(&rootfs_boot_dir, id, usr_lib_modules_vmlinuz, &repo)?;
+                // Write BLS entry to ESP
                 let efi_dir_utf8 = Utf8PathBuf::from_path_buf(efi_dir.clone())
                     .map_err(|_| anyhow::anyhow!("EFI dir is not valid UTF-8"))?;
-                write_bls_boot_entries_to_disk(&efi_dir_utf8, id, usr_lib_modules_vmlinuz, &repo)?;
+                write_bls_entry_to_esp(&efi_dir_utf8, &bls_config)?;
             }
 
             (bls_config, boot_digest)