Re: [PATCH v2] overlayfs-etc: add option to skip creation of mount dirs

[Vyacheslav Yurkov <uvv.mail@gmail.com>]

On 12.02.2024 19:30, Baruch Siach wrote:
> The 'preinit' script can't create mount directories when rootfs is
> read-only. Add an option to skip this step. The user must make sure that
> all required directories are already in the rootfs directory layout.
>
> Cc: Vyacheslav Yurkov <uvv.mail@gmail.com>
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
> v2: Add a user selectable option. Don't skip mkdir automatically when
>      read-only-rootfs feature is enabled.
> ---
>   meta/classes-recipe/overlayfs-etc.bbclass |  5 ++++-
>   meta/files/overlayfs-etc-preinit.sh.in    | 16 +++++++++-------
>   2 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/meta/classes-recipe/overlayfs-etc.bbclass b/meta/classes-recipe/overlayfs-etc.bbclass
> index 0c7834d01f43..d339fbbeee9f 100644
> --- a/meta/classes-recipe/overlayfs-etc.bbclass
> +++ b/meta/classes-recipe/overlayfs-etc.bbclass
> @@ -41,6 +41,7 @@ OVERLAYFS_ETC_USE_ORIG_INIT_NAME ??= "1"
>   OVERLAYFS_ETC_MOUNT_OPTIONS ??= "defaults"
>   OVERLAYFS_ETC_INIT_TEMPLATE ??= "${COREBASE}/meta/files/overlayfs-etc-preinit.sh.in"
>   OVERLAYFS_ETC_EXPOSE_LOWER ??= "0"
> +OVERLAYFS_ETC_CREATE_MOUNT_DIRS ??= "1"
>   
>   python create_overlayfs_etc_preinit() {
>       overlayEtcMountPoint = d.getVar("OVERLAYFS_ETC_MOUNT_POINT")
> @@ -62,6 +63,7 @@ python create_overlayfs_etc_preinit() {
>       initBaseName = oe.path.join(d.getVar("base_sbindir"), "init")
>       origInitNameSuffix = ".orig"
>       exposeLower = oe.types.boolean(d.getVar('OVERLAYFS_ETC_EXPOSE_LOWER'))
> +    createMoundDirs = oe.types.boolean(d.getVar('OVERLAYFS_ETC_CREATE_MOUNT_DIRS'))
>   
>       args = {
>           'OVERLAYFS_ETC_MOUNT_POINT': overlayEtcMountPoint,
> @@ -69,7 +71,8 @@ python create_overlayfs_etc_preinit() {
>           'OVERLAYFS_ETC_FSTYPE': overlayEtcFsType,
>           'OVERLAYFS_ETC_DEVICE': overlayEtcDevice,
>           'SBIN_INIT_NAME': initBaseName + origInitNameSuffix if useOrigInit else initBaseName,
> -        'OVERLAYFS_ETC_EXPOSE_LOWER': "true" if exposeLower else "false"
> +        'OVERLAYFS_ETC_EXPOSE_LOWER': "true" if exposeLower else "false",
> +        'CREATE_MOUNT_DIRS': "true" if createMoundDirs else "false"
>       }
>   
>       if useOrigInit:
> diff --git a/meta/files/overlayfs-etc-preinit.sh.in b/meta/files/overlayfs-etc-preinit.sh.in
> index 8db076f4ba65..b05e3957a382 100644
> --- a/meta/files/overlayfs-etc-preinit.sh.in
> +++ b/meta/files/overlayfs-etc-preinit.sh.in
> @@ -3,12 +3,15 @@
>   echo "PREINIT: Start"
>   
>   PATH=/sbin:/bin:/usr/sbin:/usr/bin
> -mount -o remount,rw /
> -
> -mkdir -p /proc
> -mkdir -p /sys
> -mkdir -p /run
> -mkdir -p /var/run
> +if {CREATE_MOUNT_DIRS}; then
> +    mount -o remount,rw /
> +
> +    mkdir -p /proc
> +    mkdir -p /sys
> +    mkdir -p /run
> +    mkdir -p /var/run
> +    mkdir -p {OVERLAYFS_ETC_MOUNT_POINT}
> +fi
>   
>   mount -t proc proc /proc
>   mount -t sysfs sysfs /sys
> @@ -20,7 +23,6 @@ UPPER_DIR=$BASE_OVERLAY_ETC_DIR/upper
>   WORK_DIR=$BASE_OVERLAY_ETC_DIR/work
>   LOWER_DIR=$BASE_OVERLAY_ETC_DIR/lower
>   
> -mkdir -p {OVERLAYFS_ETC_MOUNT_POINT}
>   if mount -n -t {OVERLAYFS_ETC_FSTYPE} \
>       -o {OVERLAYFS_ETC_MOUNT_OPTIONS} \
>       {OVERLAYFS_ETC_DEVICE} {OVERLAYFS_ETC_MOUNT_POINT}

Hi Baruch,
Thanks for the v2. Looks good now. Could you please also add a test case 
to cover the new option?

You saw from the test that mount output is parsed to confirm whether 
overlay is actually mounted. sda3 is a 3rd partition from 
https://git.openembedded.org/openembedded-core/tree/meta-selftest/wic/overlayfs_etc.wks.in 
. We could change rootfs (2nd partition) in the file to substitute the 
fs type (ext4/squashfs) from the test and then check that everything is 
mounted correctly. Does it make sense?

Thanks,
Slava