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

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

Am Fri, 22 Oct 2021 15:50:47 -0400
schrieb Joe MacDonald <joe_macdonald@mentor.com>:

> resize2fs fails if the build sets the root filesystem for an image to
> btrfs though the partition is expanded properly. Since the rest of the
> script works as intended, simply checking the last partition type with
> lsblk and adding `btrfs resize` instead of `resize2fs` in the
> appropriate circumstance allows everything to function as expected.
> 
> Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>
> ---
>  .../files/expand-last-partition.sh            | 22
> ++++++++++++++----- 1 file changed, 17 insertions(+), 5 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 7175dfd..6975d9c 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
> @@ -36,8 +36,20 @@ sfdisk -d "${BOOT_DEV}" 2>/dev/null | \ # Inform
> the kernel about the partitioning change partx -u "${LAST_PART}" -#
> Do not fail resize2fs if no mtab entry is found, e.g., -# when using
> systemd mount units. -export EXT2FS_NO_MTAB_OK=1
> -
> -resize2fs "${LAST_PART}"
> +# Determine the filesystem type and perform the appropriate resize
> function +ROOTFS_TYPE=$(lsblk -fno FSTYPE ${ROOT_DEV})

Calling "lsblk" suffers from the same udev race we have seen with
systemd-growfs ... only very subtle where we get like "" ... no
filesystem.

It seems to help to mount here and findmnt the mntpoint, we need the
mounting for btrfs anyhow.

Also lsblk can return multiple filesystems, like luks or lvm layers
underneath. Where findmnt only returns the top.

Joe, i had to rewrite your patch considerably. So i think i will change
the authorship to myself. I would really like to give you the credits
but am afraid to give you blame ... this whole expand story seems never
ending ...
So the patch will mention you, but likely not as author.

Henning

> +case ${ROOTFS_TYPE} in
> +   ext* )
> +      # Do not fail resize2fs if no mtab entry is found, e.g.,
> +      # when using systemd mount units.
> +      export EXT2FS_NO_MTAB_OK=1
> +      resize2fs "${LAST_PART}"
> +      ;;
> +   btrfs )
> +      btrfs filesystem resize max /
> +      ;;
> +   * )
> +      echo "Unrecognized filesystem type ${ROOTFS_TYPE} - no resize
> performed"
> +      exit 1
> +      ;;
> +esac