From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Sun, 15 Sep 2024 20:27:03 +0000 (+0200)
Subject: Make sure /var/tmp is not an overlayfs unless required
X-Git-Tag: v25~294^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c3ecc852f64a166a35ffa4b58fe76ed5fd76573d;p=thirdparty%2Fmkosi.git

Make sure /var/tmp is not an overlayfs unless required

If we put an overlayfs on /var because the user provided files in
/var via their sandbox tree, make sure /var/tmp is not an overlayfs
unless really required so tools like systemd-repart can make full
use of the underlying filesystem features which are disabled if
/var/tmp is on an overlayfs.
---

diff --git a/mkosi/run.py b/mkosi/run.py
index 169948b1a..e580b36d9 100644
--- a/mkosi/run.py
+++ b/mkosi/run.py
@@ -571,6 +571,13 @@ def sandbox_cmd(
                 else:
                     cmdline += ["--tmpfs", Path("/") / d]
 
+        # If we put an overlayfs on /var, and /var/tmp is not in the sandbox tree, make sure /var/tmp is a bind mount
+        # of a regular empty directory instead of the overlays so tools like systemd-repart can use the underlying
+        # filesystem features from btrfs when using /var/tmp.
+        if overlay and not (overlay / "var/tmp").exists():
+            tmp = stack.enter_context(vartmpdir())
+            cmdline += ["--bind", tmp, "/var/tmp"]
+
         yield [*cmdline, *options, "--"]