Re: [PATCH v2] expand-on-first-boot: support resizing a btrfs root

["Roberto A. Foglietta" <roberto.foglietta@gmail.com>]

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On Tue, 13 Dec 2022 at 03:10, Moessbauer, Felix
<felix.moessbauer@siemens.com> wrote:

>
> One problem remains: Where to mount.
> If we mount on /mnt this will not work on an RO rootfs out of the box.
> We currently have this issue in CIP core.
>
> We could mount below /tmp which should be writable, but I don't know
> which side effects this as the tmpfs itself will be mounted / created
> by systemd.
>

I have updated my patch to use /dev/shm but the path could be modified
setting a variable into the running environment.
The patch has been sent with git send-email using elastic smtp, so it
went into moderation. Here attached for evaluation.

Best regards, -R

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From 07a98a77f5c16b3da6c1a5e9d4fb7608fa333179 Mon Sep 17 00:00:00 2001
From: "Roberto A. Foglietta" <roberto.foglietta@gmail.com>
Date: Sat, 10 Dec 2022 04:13:42 +0100
Subject: [PATCH v2] In expand last partition script btrfs support added

Improvement, expand-on-first-boot: support for btrfs added
The mount point for btrfs filesystem to resizes is under /dev/shm
by default but a variable defined in the running enviroment can
change the temporary directory path. The /dev/shm has been choosen
because in some system /tmp can be on a RO root filesystem and
/tmp not yet mounted with tmpfs. This requires the system has
/dev/shm configured into the kernel.

Signed-off-by: Roberto A. Foglietta <roberto.foglietta@gmail.com>
---
 .../expand-on-first-boot_1.2.bb               |  2 +-
 .../files/expand-last-partition.sh            | 38 +++++++------------
 2 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb b/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb
index 0996000..fe7b72b 100644
--- a/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb
+++ b/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb
@@ -10,7 +10,7 @@ inherit dpkg-raw
 DESCRIPTION = "This service grows the last partition to the full medium during first boot"
 MAINTAINER = "isar-users <isar-users@googlegroups.com>"
 
-DEBIAN_DEPENDS = "systemd, sed, grep, coreutils, mount, e2fsprogs, fdisk (>=2.29.2-3) | util-linux (<2.29.2-3), util-linux"
+DEBIAN_DEPENDS = "systemd, sed, grep, coreutils, mount, e2fsprogs, fdisk (>=2.29.2-3) | util-linux (<2.29.2-3), util-linux, btrfs-progs"
 
 SRC_URI = " \
     file://expand-on-first-boot.service \
diff --git a/meta/recipes-support/expand-on-first-boot/files/expand-last-partition.sh b/meta/recipes-support/expand-on-first-boot/files/expand-last-partition.sh
index 4d55645..e314f70 100755
--- a/meta/recipes-support/expand-on-first-boot/files/expand-last-partition.sh
+++ b/meta/recipes-support/expand-on-first-boot/files/expand-last-partition.sh
@@ -59,29 +59,17 @@ sfdisk -d "${BOOT_DEV}" 2>/dev/null | \
 # Inform the kernel about the partitioning change
 partx -u "${LAST_PART}"
 
-# this is for debian stretch or systemd < 236
-if [ ! -x /lib/systemd/systemd-growfs ]; then
-	# Do not fail resize2fs if no mtab entry is found, e.g.,
-	# when using systemd mount units.
-	export EXT2FS_NO_MTAB_OK=1
+# Do not fail resize2fs if no mtab entry is found, e.g.,
+# when using systemd mount units.
+export EXT2FS_NO_MTAB_OK=1
 
-	resize2fs "${LAST_PART}"
-	exit 0
-fi
-
-if grep -q x-systemd.growfs /etc/fstab; then
-	echo "Found x-systemd.growfs option in /etc/fstab, won't call it explicitly." >&2
-	exit 0
-fi
-
-# mount $LAST_PART out of tree, so we won't conflict with other mounts
-MOUNT_POINT=$(mktemp -d -p /mnt "$(basename "$0").XXXXXXXXXX")
-if [ ! -d "${MOUNT_POINT}" ]; then
-	echo "Cannot create temporary mount point ${MOUNT_POINT}." >&2
-	exit 1
-fi
-
-mount "${LAST_PART}" "${MOUNT_POINT}"
-/lib/systemd/systemd-growfs "${MOUNT_POINT}"
-umount "${MOUNT_POINT}"
-rmdir "${MOUNT_POINT}"
+tmp=${BOOT_DEV_TMPDIR:-/dev/shm}
+case $(lsblk -fno FSTYPE "${LAST_PART}") in
+	ext4) 	resize2fs "${LAST_PART}"
+		;;
+	btrfs) 	mkdir -p $tmp/btrfs
+		mount "${LAST_PART}" $tmp/btrfs
+		btrfs filesystem resize max $tmp/btrfs
+		umount $tmp/btrfs && rmdir $tmp/btrfs
+		;;
+esac
-- 
2.34.1