[PATCH v4 1/5] expand-on-first-boot: support resizing a btrfs

[henning.schild@siemens.com]

From: Henning Schild <henning.schild@siemens.com>

This adds support for resizing btrfs filesystems if they are in that
last partition. It also prepares for potentially other filesystems to
come in the future by introducing a switch-case.

The mounting logic is taken from the systemd-growfs patches we had to
revert again. Some filesystems need to online for resizing, but in order
to find the filesystem of a partition (without udev) mounting it and
letting the kernel detect seems a good idea.

Suggested-by: Roberto A. Foglietta <roberto.foglietta@gmail.com>
Suggested-by: Joe MacDonald <joe_macdonald@mentor.com>
Signed-off-by: Henning Schild <henning.schild@siemens.com>
---
 .../files/expand-last-partition.sh            | 35 ++++++++++++++++---
 1 file changed, 31 insertions(+), 4 deletions(-)

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 93eddda2a3b7..0bc686059718 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
@@ -62,8 +62,35 @@ if grep -q x-systemd.growfs /etc/fstab; then
 	exit 0
 fi
 
-# Do not fail resize2fs if no mtab entry is found, e.g.,
-# when using systemd mount units.
-export EXT2FS_NO_MTAB_OK=1
+# some filesystems need to be mounted i.e. btrfs, but mounting also helps
+# detect the filesystem type without having to wait for udev
+# mount $LAST_PART out of tree, so we won't conflict with other mounts
+MOUNT_POINT=$(mktemp -d -p "" "$(basename "$0").XXXXXXXXXX")
+if [ ! -d "${MOUNT_POINT}" ]; then
+	echo "Cannot create temporary mount point ${MOUNT_POINT}." >&2
+	exit 1
+fi
+mount "${LAST_PART}" "${MOUNT_POINT}"
+
+ret=0
+# Determine the filesystem type and perform the appropriate resize function
+FS_TYPE=$(findmnt -fno FSTYPE "${MOUNT_POINT}" )
+case ${FS_TYPE} in
+ext*)
+	# Do not fail resize2fs if no mtab entry is found, e.g.,
+	# when using systemd mount units.
+	export EXT2FS_NO_MTAB_OK=1
+	resize2fs "${LAST_PART}"
+	;;
+btrfs)
+	btrfs filesystem resize max "${MOUNT_POINT}"
+	;;
+*)
+	echo "Unrecognized filesystem type ${FS_TYPE} - no resize performed"
+	ret=1
+	;;
+esac
 
-resize2fs "${LAST_PART}"
+umount "${MOUNT_POINT}"
+rmdir "${MOUNT_POINT}"
+exit $ret
-- 
2.37.4