Re: [PATCH 08/12] initscripts: let populate-volatile.sh create the /tmp link

[ChenQi <Qi.Chen@windriver.com>]

On 01/25/2013 01:39 AM, Mark Hatle wrote:
> On 1/24/13 2:16 AM, Qi.Chen@windriver.com wrote:
>> From: Chen Qi <Qi.Chen@windriver.com>
>>
>> Previously, the /tmp link (/tmp -> /var/tmp) was created by the
>> bootmisc.sh script. So in case of a read-only rootfs, this symlink
>> would not be created correctly.
>>
>> The populate-volatile.sh script is intended to handle all directories
>> and files related to volatile storage, so we should let it create
>> the /tmp link.
>>
>> In addition, because of the improments of populate-volatile.sh, the data
>> loss problem of bug#3404 is also resolved by this patch.
>>
>> [YOCTO #3406]
>> [YOCTO #3404]
>>
>> Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
>> ---
>>   .../initscripts/initscripts-1.0/bootmisc.sh        |    9 +--------
>>   .../initscripts/initscripts-1.0/volatiles          |    1 +
>>   2 files changed, 2 insertions(+), 8 deletions(-)
>>
>> diff --git 
>> a/meta/recipes-core/initscripts/initscripts-1.0/bootmisc.sh 
>> b/meta/recipes-core/initscripts/initscripts-1.0/bootmisc.sh
>> index 4f76cb4..3b5a47f 100755
>> --- a/meta/recipes-core/initscripts/initscripts-1.0/bootmisc.sh
>> +++ b/meta/recipes-core/initscripts/initscripts-1.0/bootmisc.sh
>> @@ -54,14 +54,7 @@ fi
>>
>>   #
>>   # This is as good a place as any for a sanity check
>> -# /tmp should be a symlink to /var/tmp to cut down on the number
>> -# of mounted ramdisks.
>> -if test ! -L /tmp && test -d /var/tmp
>> -then
>> -    rm -rf /tmp
>> -    ln -sf /var/tmp /tmp
>> -fi
>> -
>
> I saw this the other day.  It seems like the wrong solution, if the 
> expectation is that all systems want this linked behavior. Instead the 
> link should be configured in the meta/files/fs-perms.txt
>
> Something like:
>
> -/tmp                            01777   root    root    false - - -
> +/tmp                            link    /var/tmp
>
> Making that change would avoid this patch, and then all of the 
> filesystems could inherit this behavior.  (Other distributions that 
> don't want it can provide their own custom fs-perms.txt file, and 
> simply set the older value, which will append to the default.)
>

Thank you for your careful review :)

Here's a little more explanation on this patch. (Correct me if I'm wrong 
somewhere.)

No matter we're going to change the fs-perms.txt file or not, this patch 
is needed for things to work correctly. The populate-volatile.sh in 
sysvinit scripts, together with its configuration files, are a final 
means to ensure the directories, files and links related to volatile 
storage are created correctly.

There are link config items in fs-perms.txt.
${localstatedir}/cache    link    volatile/cache
${localstatedir}/run    link    volatile/run
${localstatedir}/log    link    volatile/log
${localstatedir}/lock    link    volatile/lock
${localstatedir}/tmp    link    volatile/tmp
There configurations are great and very reasonable, because they are 
common for different init systems.

But I'm not very sure about this link config item -- "/tmp link    
/var/tmp "

I want to restrict the creation of this link (/tmp -> /var/tmp) in the 
sysvinit scripts, because in this way, it doesn't affect other init 
systems such as systemd. The same strategy goes with the /run directory.

Here's the output from the mount command from a systemd-based 
core-image-minimal image:
root@qemux86:~# mount | grep tmpfs
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=59032k,nr_inodes=14758,mode=755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,mode=755)
tmpfs on /tmp type tmpfs (rw)
tmpfs on /var/volatile type tmpfs (rw,relatime)
tmpfs on /media/ram type tmpfs (rw,relatime)

Here's the output form the mount command from a sysv-based 
core-image-minimal image:
root@qemux86:~# mount | grep tmpfs
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=59032k,nr_inodes=14758,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime)
tmpfs on /media/ram type tmpfs (rw,relatime)

Best Regards,
Chen Qi

>> +#
>>   # Set the system clock from hardware clock
>>   # If the timestamp is more recent than the current time,
>>   # use the timestamp instead.
>> diff --git a/meta/recipes-core/initscripts/initscripts-1.0/volatiles 
>> b/meta/recipes-core/initscripts/initscripts-1.0/volatiles
>> index e0741aa..f7e2ef7 100644
>> --- a/meta/recipes-core/initscripts/initscripts-1.0/volatiles
>> +++ b/meta/recipes-core/initscripts/initscripts-1.0/volatiles
>> @@ -31,6 +31,7 @@ l root root 1777 /var/lock /var/volatile/lock
>>   l root root 0755 /var/log /var/volatile/log
>>   l root root 0755 /var/run /var/volatile/run
>>   l root root 1777 /var/tmp /var/volatile/tmp
>> +l root root 1777 /tmp /var/tmp
>>   d root root 0755 /var/lock/subsys none
>>   f root root 0664 /var/log/wtmp none
>>   f root root 0664 /var/run/utmp none
>>
>
>
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