Re: [PATCH v4 1/1] expand-on-first-boot: Switch from resize2fs to systemd-growfs

[Henning Schild <henning.schild@siemens.com>]

Am Wed, 29 Jun 2022 14:01:44 +0200
schrieb Tobias Schmidl <tobiasschmidl@siemens.com>:

> We want to be more versatile in our approach of resizing the last
> partition. Therefore we switch from resize2fs to systemd-growfs.
> 
> This allows for ext4, btrfs, xfs, and dm-crypt partitions to be
> resized.
> 
> Since systemd-growfs landed in v236, this obsoletes
> expand-on-first-boot on stretch (v232).
> 
> Signed-off-by: Tobias Schmidl <tobiasschmidl@siemens.com>
> ---
>  ...oot_1.1.bb => expand-on-first-boot_1.2.bb} |  5 +++--
>  .../files/expand-last-partition.sh            | 21
> +++++++++++++++++-- 2 files changed, 22 insertions(+), 4 deletions(-)
>  rename
> meta/recipes-support/expand-on-first-boot/{expand-on-first-boot_1.1.bb
> => expand-on-first-boot_1.2.bb} (78%)
> 
> diff --git
> a/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.1.bb
> b/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb
> similarity index 78% rename from
> meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.1.bb
> rename to
> meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb
> index 1703a64..48d30d3 100644 ---
> a/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.1.bb
> +++
> b/meta/recipes-support/expand-on-first-boot/expand-on-first-boot_1.2.bb
> @@ -1,15 +1,16 @@ # Resize last partition to full medium size on fist
> boot # # This software is a part of ISAR. -# Copyright (c) Siemens
> AG, 2018 +# Copyright (c) Siemens AG, 2018-2022 #
>  # SPDX-License-Identifier: MIT
>  
>  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, util-linux" +DEBIAN_DEPENDS = "systemd (>=236), sed, grep,
> coreutils, mount, fdisk, util-linux" 
>  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 c0edde7..1743890 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
> @@ -3,7 +3,7 @@ # Resize last partition to full medium size # # This
> software is a part of ISAR. -# Copyright (c) Siemens AG, 2018
> +# Copyright (c) Siemens AG, 2018-2022
>  #
>  # SPDX-License-Identifier: MIT
>  
> @@ -45,4 +45,21 @@ partx -u "${LAST_PART}"
>  # when using systemd mount units.
>  export EXT2FS_NO_MTAB_OK=1
>  
> -resize2fs "${LAST_PART}"
> +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

I guess we might need some comments here. In the other mail you wrote
that the fstab magic string did not work as expected, but i guess that
was the attempt to smuggle it in without actually having it in fstab.

Does the combination of expand-on-first-boot (in the proposed version)
work together with the fstab string set on the last partition?
I would assume it would not because the service is executed too late,
or it might work on the second boot ... It is probably good to bail
when finding that string in fstab, but for people reading the code they
might think that they could as well write it into fstab to reach a fs
growing that way.

Henning

> +
> +MOUNT_POINT=$(findmnt -o target -n "${LAST_PART}")
> +UNMOUNT_AFTERWORDS=0
> +if [ -z "${MOUNT_POINT}" ]; then
> +	MOUNT_POINT=$(findmnt -o target -n --fstab "{$LAST_PART}")
> +	if [ -z "${MOUNT_POINT}" ]; then
> +		echo "Cannot find mount point for ${LAST_PART}" >&2
> +		exit 1
> +	else
> +		UNMOUNT_AFTERWORDS=1
> +	fi
> +fi
> +/lib/systemd/systemd-growfs "${MOUNT_POINT}"
> +[ $UNMOUNT_AFTERWORDS -eq 1 ] && umount "${MOUNT_POINT}"