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

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

Am Mon, 25 Oct 2021 10:10:54 +0200
schrieb Henning Schild <henning.schild@siemens.com>:

> Yes, good addition! But it would be even better if we had it running
> in CI. We could switch one target over to btrfs by providing an
> example wks file, one that boots an image in qemu.
> That way we would have a btrfs example in the tree and get confident
> that wic will do things as i would hope for.
> 
> 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})
> > +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 /  
> 
> Need to do something to "DEBIAN_DEPENDS", maybe "e2fsprogs" ->
> "e2fsprogs | btrfs-progs".

It is in fact more complicated than that. The two "progs" should not
both be depended on, because we would install too much stuff. We can
not use "|" because we will not know which one we get. Say one was
installed for any other reason, the one we need for rootfs might not
get pulled in.
Recommends would be better, but isar will not pull them. (still would
be an idea to be "correct")

We could also spit out two packages "expand-on-first-boot-ext|btrfs"
but that does not scale well for the next fs to cover.

So i would say "Recommends: e2fsprogs, btrfs-progs" and make that
script "command -v" and cry. Maybe keeping e2fsprogs in a first patch,
and removing it from Depends in a second interface-breaking patch.

regards,
Henning

> > +      ;;
> > +   * )
> > +      echo "Unrecognized filesystem type ${ROOTFS_TYPE} - no resize
> > performed"
> > +      exit 1
> > +      ;;
> > +esac  
>