Re: [PATCH 2/2] image.bbclass: Empty /var/volatile if it is a mount point

[Randy Witt <randy.e.witt@linux.intel.com>]

On 03/24/2015 08:53 AM, Khem Raj wrote:
>
>> On Mar 24, 2015, at 8:46 AM, randy.e.witt@linux.intel.com wrote:
>>
>>> On Mon, Mar 23, 2015 at 5:28 PM, Randy Witt
>>> <randy.e.witt@linux.intel.com> wrote:
>>>> If /var/volatile is a mount point it shouldn't contain any files before
>>>> mount time. If files are there, they will no longer be able to be
>>>> accessed
>>>> once the tmpfs gets mounted at /var/volatile.
>>>
>>> why not use copy-bind when mounting it second time as tmpfs ?
>>>
>>
>> Khem, could you elaborate? I'm not sure I know the mechanism to which you
>> are referring.
>
> copy bind will copy the contents from old place to new mount. Then hopefully you do not lose the content
> that was already there before remount happens see VOLATILE_BINDS implementation.
>

I like this idea, but considering that /var/volatile/log/journal is within the 
mountpoint I'm not sure how it could work. The contents will already be hidden 
by the mount of /var/volatile before the files can be copied.

Perhaps I am misunderstanding?

>>
>>>>
>>>> This problem can be seen for instance when systemd creates
>>>> /var/volatile/log/journal as part of its package installation. It then
>>>> assumes the journal is persistent even though /var/volatile/log/journal
>>>> goes away shortly thereafter.
>>>>
>>>> This change makes sure that there are no files in /var/volatile if it is
>>>> to be used as a mount point.
>>>>
>>>> [Yocto #7388]
>>>>
>>>> Signed-off-by: Randy Witt <randy.e.witt@linux.intel.com>
>>>> ---
>>>> meta/classes/image.bbclass | 16 ++++++++++++++++
>>>> 1 file changed, 16 insertions(+)
>>>>
>>>> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
>>>> index 89eb5f3..dfedf9d 100644
>>>> --- a/meta/classes/image.bbclass
>>>> +++ b/meta/classes/image.bbclass
>>>> @@ -181,6 +181,8 @@ POSTINST_LOGFILE ?=
>>>> "${localstatedir}/log/postinstall.log"
>>>> SYSTEMD_DEFAULT_TARGET ?= '${@bb.utils.contains("IMAGE_FEATURES",
>>>> "x11-base", "graphical.target", "multi-user.target", d)}'
>>>> ROOTFS_POSTPROCESS_COMMAND += '${@bb.utils.contains("DISTRO_FEATURES",
>>>> "systemd", "set_systemd_default_target; ", "", d)}'
>>>>
>>>> +ROOTFS_POSTPROCESS_COMMAND += 'empty_var_volatile;'
>>>> +
>>>> # some default locales
>>>> IMAGE_LINGUAS ?= "de-de fr-fr en-gb"
>>>>
>>>> @@ -377,6 +379,20 @@ set_systemd_default_target () {
>>>>         fi
>>>> }
>>>>
>>>> +# If /var/volatile is not empty, we have seen problems where programs
>>>> such as the
>>>> +# journal make assumptions based on the contents of /var/volatile. The
>>>> journal
>>>> +# would then write to /var/volatile before it was mounted, thus hiding
>>>> the
>>>> +# items previously written.
>>>> +#
>>>> +# This change is to attempt to fix those types of issues in a way that
>>>> doesn't
>>>> +# affect users that may not be using /var/volatile.
>>>> +empty_var_volatile () {
>>>> +       match=`awk '$1 !~ "#" && $2 ~ /\/var\/volatile/{print $2}'
>>>> ${IMAGE_ROOTFS}/etc/fstab 2> /dev/null`
>>>> +       if [ -n "$match" ]; then
>>>> +               find ${IMAGE_ROOTFS}/var/volatile -mindepth 1 -delete
>>>> +       fi
>>>> +}
>>>> +
>>>> # Turn any symbolic /sbin/init link into a file
>>>> remove_init_link () {
>>>>         if [ -h ${IMAGE_ROOTFS}/sbin/init ]; then
>>>> --
>>>> 1.9.3
>>>>
>>>> --
>>>> _______________________________________________
>>>> Openembedded-core mailing list
>>>> Openembedded-core@lists.openembedded.org
>>>> http://lists.openembedded.org/mailman/listinfo/openembedded-core
>>>
>>
>