[PATCH] expand-on-first-boot: Add support for devicemapper

[Jan Kiszka <jan.kiszka@siemens.com>]

From: Jan Kiszka <jan.kiszka@siemens.com>

When the rootfs is inside a devicemapper volume, e.g. dm-verity, the
script so far fails to identify the boot device. This adds at least
basic support for that case (single level, single slave). Once there is
a good example for more complex setups, this could be taken into account
as well.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 .../expand-on-first-boot/files/expand-last-partition.sh    | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

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 7175dfd3..bb371e9f 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
@@ -10,8 +10,13 @@
 set -e
 
 ROOT_DEV="$(findmnt / -o source -n)"
-BOOT_DEV="$(echo "${ROOT_DEV}" | sed 's/p\?[0-9]*$//')"
+ROOT_DEV_NAME=${ROOT_DEV##*/}
+ROOT_DEV_SLAVE=$(ls -d /sys/block/${ROOT_DEV_NAME}/slaves/* 2>/dev/null | head -1)
+if [ -n ${ROOT_DEV_SLAVE} ]; then
+	ROOT_DEV=/dev/${ROOT_DEV_SLAVE##*/}
+fi
 
+BOOT_DEV="$(echo "${ROOT_DEV}" | sed 's/p\?[0-9]*$//')"
 if [ "${ROOT_DEV}" = "${BOOT_DEV}" ]; then
 	echo "Boot device equals root device - no partitioning found" >&2
 	exit 1
-- 
2.34.1