Re: [PATCH v2 1/1] expand-on-first-boot: Check size before resizing

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

LGTM, i also like the idea of asking whether it is worth growing instead
of asking the more complicated question whether we would potentially
shrink trying to grow.

Henning

Am Mon, 11 Jul 2022 10:16:02 +0200
schrieb Tobias Schmidl <tobiasschmidl@siemens.com>:

> If the disk is too small, resizing might have detrimental effects.
> Because of aligning issues, it could happen the the final partition is
> _smaller_ than desired, which might lead to an unusable last
> partition.
> 
> Signed-off-by: Tobias Schmidl <tobiasschmidl@siemens.com>
> ---
>  .../files/expand-last-partition.sh               | 16
> ++++++++++++++++ 1 file changed, 16 insertions(+)
> 
> 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..0aa1063 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
> @@ -22,6 +22,22 @@ if [ "${ROOT_DEV}" = "${BOOT_DEV}" ]; then exit 1
> fi +# this value is in blocks. Normally a block has 512 bytes.
> +BUFFER_SIZE=32768
> +BOOT_DEV_NAME=${BOOT_DEV##*/}
> +DISK_SIZE="$(cat /sys/class/block/"${BOOT_DEV_NAME}"/size)"
> +ALL_PARTS_SIZE=0
> +for PARTITION in /sys/class/block/"${BOOT_DEV_NAME}"[1-9]*; do
> +	PART_SIZE=$(cat "${PARTITION}"/size)
> +	ALL_PARTS_SIZE=$((ALL_PARTS_SIZE + PART_SIZE))
> +done
> +
> +MINIMAL_SIZE=$((ALL_PARTS_SIZE + BUFFER_SIZE))
> +if [ "$DISK_SIZE" -lt "$MINIMAL_SIZE" ]; then
> +	echo "Disk is practically already full, doing nothing." >&2
> +	exit 0
> +fi
> +
>  LAST_PART="$(sfdisk -d "${BOOT_DEV}" 2>/dev/null | tail -1 | cut -d
> ' ' -f 1)" 
>  # Transform the partition table as follows: