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

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

Hi Jan,

On 12/6/18 2:17 PM, Jan Kiszka wrote:
> On 06.12.18 10:44, Maxim Yu. Osipov wrote:
>> Just to doublecheck: What is your patch queue for that?
>>
> 
> Just updated jan/queue on github.com/siemens/isar. It's not the best 
> ordering of patches, this fix should probably come earlier, but the top 
> is what I tested successfully also in a stretch VM.

I'm convinced that this patch fixes these two issues.
CI passes OK on my stretch laptop.
It fails on isar-build.org by evident reason (CI runs in stretch chroot 
on jessie host - the host's kernel 3.16 has troubles with 'mount 
--rbind'). We are now upgrading the host system.

When applying to the 'next' I may rearrange the ordering of patches in 
more logical path

git log --oneline:

c46ad1b isar-image: Make do_rootfs normal shell function
05d0fc4 isar-events: Improve umount handler
93c4795 ci: Make partial rebuild test non-destructive
4ca0bff ci: Wait for bitbake worker to finish before deleting artifacts
698fb56 Remove redundant recursive umounts
bbc61fb wic-img: Fix bind mounting
9cf29e6 isar-bootstrap: Fix and cleanup bind mounting
b354026 isar-image: umount base-apt when doing offline build
e965c0d gitlab-ci: Switch to ci_build.sh

is it OK?

Maxim.


> Jan
> 
>> 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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