osbuild: add patch to set TMPDIR for mkfs.erofs

This will help reduce the memory requirements of mkfs.erofs.
osbuild/osbuild#2020

Author: dustymabe

build.sh

@@ -172,6 +172,7 @@ patch_osbuild() {
     cat /usr/lib/coreos-assembler/0001-stages-coreos.live-artifacts-add-erofs-support.patch       \
         /usr/lib/coreos-assembler/0002-stages-coreos.live-artifacts-update-comments-names-t.patch \
         /usr/lib/coreos-assembler/0001-stages-add-more-options-to-qemu-vmdk-disk-type.patch       \
+        /usr/lib/coreos-assembler/0001-stages-coreos.live-artifacts-use-var-tmp-for-mkfs.er.patch \
             | patch -d /usr/lib/osbuild -p1
 
     # And then move the files back; supermin appliance creation will need it back

src/0001-stages-coreos.live-artifacts-use-var-tmp-for-mkfs.er.patch

@@ -0,0 +1,35 @@
+From 31faba33b71feb160f436aaf4c9ac9932cb68830 Mon Sep 17 00:00:00 2001
+From: Dusty Mabe <[email protected]>
+Date: Fri, 14 Feb 2025 12:23:48 -0500
+Subject: [PATCH] stages/coreos.live-artifacts: use /var/tmp for mkfs.erofs
+
+This helps reduce the memory requirements of mkfs.erofs since
+it won't be writing to tmpfs (memory backed) storage, which is
+what is mounted on /tmp/.
+---
+ stages/org.osbuild.coreos.live-artifacts.mono | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/stages/org.osbuild.coreos.live-artifacts.mono b/stages/org.osbuild.coreos.live-artifacts.mono
+index 302b24d3..a5837deb 100755
+--- a/stages/org.osbuild.coreos.live-artifacts.mono
++++ b/stages/org.osbuild.coreos.live-artifacts.mono
+@@ -606,10 +606,14 @@ def mkrootfs_metal(paths, workdir, img_metal, fstype, fsoptions, loop_client):
+             # Note the filename must be exactly "root.[squash|ero]fs"
+             # because the 35coreos-live dracut module requires it.
+             if fstype == "erofs":
++                # Set TMPDIR='/var/tmp' to write temporary files into non-tmpfs
++                # (memory backed) storage. This helps reduce memory requirements.
++                # https://github.com/erofs/erofs-utils/issues/13
+                 subprocess.check_call(['mkfs.erofs',
+                                        *fsoptions.split(' '),
+                                        paths["initrd-rootfs/root.erofs"],
+-                                       tmp_rootfs_dir])
++                                       tmp_rootfs_dir],
++                                      env=dict(os.environ, TMPDIR='/var/tmp'))
+             else:
+                 subprocess.check_call(['mksquashfs', tmp_rootfs_dir,
+                                        paths["initrd-rootfs/root.squashfs"],
+-- 
+2.48.1
+