Re: [PATCH] wic-img: Fix bind mounting

["Maxim Yu. Osipov" <mosipov@ilbers.de>]

Just to doublecheck: What is your patch queue for that?

On 12/6/18 11:13 AM, Jan Kiszka wrote:
> 
> This addresses two issues of the current code:
> 
>   - we must make the bind mount of STAGING_DIR private because it will
>     otherwise pick up bind mounts done underneath it in the various
>     rootfs used by parallel targets
> 
>   - locking was missing to make check and mount atomic, just like we do
>     inside buildchroot_do_mounts
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> My theory on what went wrong /wrt rbind-mounted /sys and /dev: As the
> bind-mounting of STAGING_DIR of a wic target (qemu-amd64) eventually
> started to contain shared(!) bind-mounts of parallel targets (qemu-
> armhf, qemu-arm64), and all those stick to the end, isar_handler started
> to umount their now also shared /dev and /sys mounts. And that
> destroyed the host mounts.
> 
> Lesson to be recalled: never paper over issues that were not yet fully
> understood. They may point to sleeping problems that will only bite you
> again later.
> 
>   meta/classes/wic-img.bbclass | 13 ++++++++-----
>   1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/meta/classes/wic-img.bbclass b/meta/classes/wic-img.bbclass
> index 225463e..76602d8 100644
> --- a/meta/classes/wic-img.bbclass
> +++ b/meta/classes/wic-img.bbclass
> @@ -87,11 +87,14 @@ do_build[stamp-extra-info] = "${DISTRO}-${DISTRO_ARCH}"
>   
>   do_wic_image() {
>       buildchroot_do_mounts
> -    for dir in ${BBLAYERS} ${STAGING_DIR} ${ISARROOT}/scripts; do
> -	sudo mkdir -p ${BUILDCHROOT_DIR}/$dir
> -        mountpoint ${BUILDCHROOT_DIR}/$dir >/dev/null 2>&1 \
> -        || sudo mount --bind $dir ${BUILDCHROOT_DIR}/$dir
> -    done
> +    sudo flock ${MOUNT_LOCKFILE} -c ' \
> +        for dir in ${BBLAYERS} ${STAGING_DIR} ${ISARROOT}/scripts; do
> +            mkdir -p ${BUILDCHROOT_DIR}/$dir
> +            if ! mountpoint ${BUILDCHROOT_DIR}/$dir >/dev/null 2>&1; then
> +                mount --bind --make-private $dir ${BUILDCHROOT_DIR}/$dir
> +            fi
> +        done
> +        '
>       export FAKEROOTCMD=${FAKEROOTCMD}
>       export BUILDDIR=${BUILDDIR}
>       export MTOOLS_SKIP_CHECK=1
> 


-- 
Maxim Osipov
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