Re: [PATCH] isar-image-base: fix some dangling mounts

[Alexander Smirnov <asmirnov@ilbers.de>]

Hi,

On 11/13/2017 03:22 PM, Christian Storm wrote:
> As bitbake/lib/bb/build.py's shell_trap_code() injects
> `set -e` into scripts, the premature end of scripts leaves
> dangling mounts around. Fix these dangling mounts by hooking
> into the EXIT trap handler also setup by shell_trap_code().
> 

Thank you for the explanation (in another main), now I've got the idea!

> Signed-off-by: Christian Storm <christian.storm@siemens.com>
> ---
>   meta-isar/recipes-core/images/isar-image-base.bb | 10 ++++++++--
>   meta/classes/dpkg-base.bbclass                   | 10 ++++++++--
>   meta/classes/ext4-img.bbclass                    | 10 ++++++++--
>   meta/recipes-devtools/buildchroot/buildchroot.bb | 10 ++++++++--
>   4 files changed, 32 insertions(+), 8 deletions(-)
> 
> diff --git a/meta-isar/recipes-core/images/isar-image-base.bb b/meta-isar/recipes-core/images/isar-image-base.bb
> index 42aaea3..c2150b1 100644
> --- a/meta-isar/recipes-core/images/isar-image-base.bb
> +++ b/meta-isar/recipes-core/images/isar-image-base.bb
> @@ -52,8 +52,14 @@ do_rootfs() {
>           -e 's|##ISAR_DISTRO_SUITE##|${DEBDISTRONAME}|g' \
>              "${WORKDIR}/multistrap.conf.in" > "${WORKDIR}/multistrap.conf"
>   
> -    install -d -m 555 ${IMAGE_ROOTFS}/proc
> +    [ ! -d ${IMAGE_ROOTFS}/proc ] && install -d -m 555 ${IMAGE_ROOTFS}/proc
>       sudo mount -t proc none ${IMAGE_ROOTFS}/proc
> +    _do_rootfs_cleanup() {
> +        ret=$?
> +        sudo umount ${IMAGE_ROOTFS}/proc 2>/dev/null || true
> +        (exit $ret) || bb_exit_handler
> +    }
> +    trap '_do_rootfs_cleanup' EXIT
>   
>       # Create root filesystem
>       sudo multistrap -a ${DISTRO_ARCH} -d "${IMAGE_ROOTFS}" -f "${WORKDIR}/multistrap.conf"
> @@ -62,7 +68,7 @@ do_rootfs() {
>       sudo chroot ${IMAGE_ROOTFS} /${DISTRO_CONFIG_SCRIPT} ${MACHINE_SERIAL} ${BAUDRATE_TTY} \
>           ${ROOTFS_DEV}
>       sudo rm "${IMAGE_ROOTFS}/${DISTRO_CONFIG_SCRIPT}"
> -    sudo umount ${IMAGE_ROOTFS}/proc
> +    _do_rootfs_cleanup
>   }
>   
>   addtask rootfs before do_build after do_populate
> diff --git a/meta/classes/dpkg-base.bbclass b/meta/classes/dpkg-base.bbclass
> index 9ded3ae..35af6d5 100644
> --- a/meta/classes/dpkg-base.bbclass
> +++ b/meta/classes/dpkg-base.bbclass
> @@ -21,9 +21,15 @@ dpkg_runbuild() {
>   do_build() {
>       mkdir -p ${BUILDROOT}
>       sudo mount --bind ${WORKDIR} ${BUILDROOT}
> +    _do_build_cleanup() {
> +        ret=$?
> +        sudo umount ${BUILDROOT} 2>/dev/null || true
> +        sudo rmdir ${BUILDROOT} 2>/dev/null || true
> +        (exit $ret) || bb_exit_handler
> +    }
> +    trap '_do_build_cleanup' EXIT
>       dpkg_runbuild
> -    sudo umount ${BUILDROOT}
> -    rm -rf ${BUILDROOT}
> +    _do_build_cleanup
>   }
>   
>   # Install package to dedicated deploy directory
> diff --git a/meta/classes/ext4-img.bbclass b/meta/classes/ext4-img.bbclass
> index 18a74ca..83cb137 100644
> --- a/meta/classes/ext4-img.bbclass
> +++ b/meta/classes/ext4-img.bbclass
> @@ -19,9 +19,15 @@ do_ext4_image() {
>   
>       mkdir -p ${WORKDIR}/mnt
>       sudo mount -o loop ${EXT4_IMAGE_FILE} ${WORKDIR}/mnt
> +    _do_ext4_image_cleanup() {
> +        ret=$?
> +        sudo umount ${WORKDIR}/mnt 2>/dev/null || true
> +        sudo rmdir ${WORKDIR}/mnt 2>/dev/null || true
> +        (exit $ret) || bb_exit_handler
> +    }
> +    trap '_do_ext4_image_cleanup' EXIT
>       sudo cp -r ${IMAGE_ROOTFS}/* ${WORKDIR}/mnt
> -    sudo umount ${WORKDIR}/mnt
> -    rm -r ${WORKDIR}/mnt
> +    _do_ext4_image_cleanup
>   }
>   
>   addtask ext4_image before do_build after do_copy_boot_files
> diff --git a/meta/recipes-devtools/buildchroot/buildchroot.bb b/meta/recipes-devtools/buildchroot/buildchroot.bb
> index ace64ba..4cae9fc 100644
> --- a/meta/recipes-devtools/buildchroot/buildchroot.bb
> +++ b/meta/recipes-devtools/buildchroot/buildchroot.bb
> @@ -52,8 +52,14 @@ do_build() {
>           -e 's|##DIR_HOOKS##|./'"$WORKDIR_REL"'/hooks_multistrap|g' \
>              "${WORKDIR}/multistrap.conf.in" > "${WORKDIR}/multistrap.conf"
>   
> -    install -d -m 555 ${BUILDCHROOT_DIR}/proc
> +    [ ! -d ${BUILDCHROOT_DIR}/proc ] && install -d -m 555 ${BUILDCHROOT_DIR}/proc
>       sudo mount -t proc none ${BUILDCHROOT_DIR}/proc
> +    _do_build_cleanup() {
> +        ret=$?
> +        sudo umount ${BUILDCHROOT_DIR}/proc 2>/dev/null || true
> +        (exit $ret) || bb_exit_handler
> +    }
> +    trap '_do_build_cleanup' EXIT
>   
>       # Create root filesystem
>       sudo multistrap -a ${DISTRO_ARCH} -d "${BUILDCHROOT_DIR}" -f "${WORKDIR}/multistrap.conf"
> @@ -63,5 +69,5 @@ do_build() {
>   
>       # Configure root filesystem
>       sudo chroot ${BUILDCHROOT_DIR} /configscript.sh
> -    sudo umount ${BUILDCHROOT_DIR}/proc
> +    _do_build_cleanup
>   }
> 

Here I see that you insert quite similar patterns across the Isar code, 
would it be better to have one global clean up function like?

do_isar_mount_cleanup () {
     if [ -d "${WORKDIR}/mnt" ]; then
         # umount and remove
     fi

     if [ -d "${WORKDIR}/rootfs/proc" ]; then
         # umount and remove
     fi

     if [ -d "${BUILDCHROOT_DIR}/proc" ]; then
         # umount and remove
     fi

     etc...
}

This approach will significantly simplify maintenance of clean up traps 
and adding of new possible mounts to Isar. What do you think?

Alex