Re: [OE-core] [RFC PATCH V2 0/5] Fix persistent tmp

[Randy MacLeod via lists.openembedded.org]

Add Trevor who made the original commit:

commit d5d40479d706cbb382850b9479c5dd9bfb801c99
Author: Trevor Woerner <twoer...@gmail.com>
Date:   Mon Feb 27 00:00:40 2023
    VOLATILE_TMP_DIR: add

    Provide a mechanism to allow users to choose whether the /tmp directory
    is on persistent storage (non-volatile) or a RAM-based tmpfs 
(volatile).
    The default is volatile.

    Works for both sysvinit-based and systemd-based systems.


and Ross who said he'd take a look at this RFC.


On 2024-02-03 9:58 p.m., Changqing Li via lists.openembedded.org wrote:
ping

On 12/11/23 08:58, Changqing Li wrote:
From: Changqing Li <changqing...@windriver.com>

Hi, All

Currently, VOLATILE_TMP_DIR not works,
set VOLATILE_TMP_DIR="no", VOLATILE_LOG_DIR="no", after boot target,
/var/tmp still link to tmpfs /var/volatile/tmp

lrwxrwxrwx  1 root root   11 Mar  9  2018 lock -> ../run/lock
drwxr-xr-x  4 root root 1024 Dec  4 07:55 log
lrwxrwxrwx  1 root root    6 Mar  9  2018 run -> ../run
drwxr-xr-x  3 root root 1024 Mar  9  2018 spool
lrwxrwxrwx  1 root root   12 Mar  9  2018 tmp -> volatile/tmp
drwxrwxrwt  4 root root   80 Dec  4 07:55 volatile

So I do some research, fix this issue and do some other changes 
accordingly. Please
help to review this patch, thanks.

Targets:
1. Support persistent tmp,  For persistent tmp, only /var/tmp is 
persistent, /tmp is tmpfs,
    For volatile tmp, /tmp link to /var/tmp, /var/tmp link to 
/var/volatile/tmp
2. make systemd and SysVinit have the same directory structure.

Currently, systemd and SysVinit have different directory structure, 
the difference focus on how to handle /tmp.

when volatile is enabled, for sysVinit, /tmp link to /var/tmp, 
/var/tmp link to /var/volatile/tmp
refer [4][5]. but for systemd, /tmp is a directory, it is mounted by 
systemd as tmpfs. /var/tmp
linked to /var/volatile/tmp.  And for systemd, refer [6], set 
different age for /tmp and /var/tmp.

I find that structured text helps me understand things, so here's a 
structured version of the sentences above:


Currently, systemd and SysVinit have different directory structure; the 
difference focus on how to handle /tmp.

When volatile is enabled, for sysVinit:
      /tmp link to /var/tmp,
      /var/tmp link to /var/volatile/tmp
   refer [4][5]

but for systemd:
       /tmp is a directory, it is mounted by systemd as tmpfs.
      /var/tmp linked to /var/volatile/tmp

and for systemd, refer [6], set different age for /tmp and /var/tmp.





Since volatile disabled not works, ignore the difference when 
volatile is disabled.

With this patch, VOLATILE_TMP_DIR will behavior like this:
For both sysvinit and systemd:
1. VOLATILE_TMP_DIR="yes":
/tmp link to /var/tmp,  /var/tmp link to /var/volatile/log, 
/var/volatile is mounted as tmpfs
In this case, for systemd, /tmp and /var/tmp will set to the same 
age, 10d.

Compare to current behavior, there are 2 changes:
    1) for systemd,  /tmp changed from a directy to a symlink to 
/var/tmp
    2) age of /tmp and /var/tmp will be same


Okay but is an identical timestamp absolutely required or are you just 
trying to make things consistent

to reduce the chance that a different timestamp could cause problems?

I may have missed an explanation of why you want the 10d old timestamp 
anyway, that seems like
a separate change that should follow-up the re-org changes.



2. VOLATILE_TMP_DIR="no":
/tmp is a directory mounted as tmpfs, /var/tmp is a directory on 
persistent fs, and keep the age as [6]

Change like this in order to meet [1][2], also maybe [3] for systemd.

Compare to current behavior, there is one change:
    1) for sysVinit, /tmp changed from a symlink to a directory

You've carefully explained things but it does seem a bit complicated 
when you first read
the explaination. It may have been better to start your explaination 
with the last statement you
made, by saying something like this:

   This is going to be a detailed, lengthy explaination but the only 
change in runtime will be
   for sysVinit where /tmp is changed from a symlink to a directory to 
make it persistent.


Ross, Trevor,
Any comments or concerns ?

Changqing is no one replies today, please just rebase and repost your 
full RFC patch
to try to restart the discussion.


Thanks,

../Randy


[1] https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s18.html
[2] https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch05s15.html
[3] https://systemd.io/TEMPORARY_DIRECTORIES/
[4] 
https://git.openembedded.org/openembedded/tree/docs/usermanual/chapters/recipes.xml#n3535
[5] 
https://git.openembedded.org/openembedded-core/commit/?id=12c4acd7ac5a27cf3676065b60f1c8395c96854c
[6] https://github.com/systemd/systemd/blob/main/tmpfiles.d/tmp.conf
[7] 
https://www.freedesktop.org/software/systemd/man/latest/tmpfiles.d.html


Test Result of following cases:
1.
SysVinit
VOLATILE_TMP_DIR="yes"
VOLATILE_LOG_DIR="yes"

root@qemux86-64:~# ls -al /tmp
lrwxrwxrwx    1 root     root             8 Dec  8 08:51 /tmp -> 
/var/tmp
root@qemux86-64:~# ls -al /var/log
lrwxrwxrwx    1 root     root            17 Dec  8 08:51 /var/log -> 
/var/volatile/log
root@qemux86-64:~# ls -al /var/tmp
lrwxrwxrwx    1 root     root            17 Dec  8 08:51 /var/tmp -> 
/var/volatile/tmp
root@qemux86-64:~# mount | grep volatile
tmpfs on /var/volatile type tmpfs (rw,relatime)
root@qemux86-64:~#

2.
SysVinit
VOLATILE_TMP_DIR="no"
VOLATILE_LOG_DIR="no"

root@qemux86-64:/# ls -al
drwxr-xr-x   18 root     root          1024 Dec  8 09:22 .
drwxr-xr-x   18 root     root          1024 Dec  8 09:22 ..
drwxr-xr-x    2 root     root          3072 Mar  9  2018 bin
drwxr-xr-x    2 root     root          1024 Mar  9  2018 boot
drwxr-xr-x   13 root     root          2960 Dec  8 09:24 dev
drwxr-xr-x   20 root     root          1024 Dec  8 09:24 etc
drwxr-xr-x    3 root     root          1024 Mar  9  2018 home
drwxr-xr-x    6 root     root          1024 Mar  9  2018 lib
drwx------    2 root     root         12288 Dec  8 09:22 lost+found
drwxr-xr-x    2 root     root          1024 Mar  9  2018 media
drwxr-xr-x    2 root     root          1024 Mar  9  2018 mnt
dr-xr-xr-x  161 root     root             0 Dec  8 09:24 proc
drwxr-xr-x    4 root     root           240 Dec  8 09:24 run
drwxr-xr-x    2 root     root          3072 Mar  9  2018 sbin
dr-xr-xr-x   12 root     root             0 Dec  8 09:24 sys
drwxrwxrwt    2 root     root            40 Dec  8 09:24 tmp
drwxr-xr-x    9 root     root          1024 Mar  9  2018 usr
drwxr-xr-x   10 root     root          1024 Dec  8 09:24 var
root@qemux86-64:/# cd /var/
root@qemux86-64:/var# ls -al
drwxr-xr-x   10 root     root          1024 Dec  8 09:24 .
drwxr-xr-x   18 root     root          1024 Dec  8 09:22 ..
drwxr-xr-x    2 root     root          1024 Mar  9  2018 backups
drwxr-xr-x    2 root     root          1024 Mar  9  2018 cache
drwxr-xr-x    4 root     root          1024 Mar  9  2018 lib
drwxr-xr-x    2 root     root          1024 Mar  9  2018 local
lrwxrwxrwx    1 root     root             9 Dec  8 09:24 lock -> 
/run/lock
drwxr-xr-x    2 root     root          1024 Dec  8 09:24 log
lrwxrwxrwx    1 root     root             4 Dec  8 09:24 run -> /run
drwxr-xr-x    2 root     root          1024 Mar  9  2018 spool
drwxrwxrwt    2 root     root          1024 Mar  9  2018 tmp
drwxrwxrwt    4 root     root            80 Dec  8 09:24 volatile
root@qemux86-64:/var# mount | grep tmpfs
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=1012164k,nr_inodes=253041,mode=755)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,nr_inodes=1048576)
root@qemux86-64:/var#


3.
systemd
VOLATILE_TMP_DIR="yes"
VOLATILE_LOG_DIR="yes"

root@qemux86-64:/# ls -al /tmp
lrwxrwxrwx    1 root     root             8 Dec  8 08:49 /tmp -> 
/var/tmp
            8 Dec  8 08:49 /tmp -> /var/tmp
root@qemux86-64:/# cd /var/
root@qemux86-64:/var# ls -al tmp
lrwxrwxrwx    1 root     root            12 Mar  9  2018 tmp -> 
volatile/tmp
root@qemux86-64:/var# ls -al log
lrwxrwxrwx    1 root     root            12 Mar  9  2018 log -> 
volatile/log
root@qemux86-64:/var# mount | grep tmp
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=1012160k,nr_inodes=253040,mode=755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run type tmpfs 
(rw,nosuid,nodev,size=405732k,nr_inodes=819200,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs 
(ro,nosuid,nodev,noexec,size=4096k,nr_inodes=1024,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime)
root@qemux86-64:/var#

4.
systemd
VOLATILE_TMP_DIR="no"
VOLATILE_LOG_DIR="no"

root@qemux86-64:/# ls -al
drwxr-xr-x   17 root     root          1024 Dec  8 09:16 .
drwxr-xr-x   17 root     root          1024 Dec  8 09:16 ..
lrwxrwxrwx    1 root     root             7 Mar  9  2018 bin -> usr/bin
drwxr-xr-x    2 root     root          1024 Mar  9  2018 boot
drwxr-xr-x   14 root     root          3260 Dec  8 09:16 dev
drwxr-xr-x   21 root     root          3072 Dec  8 09:16 etc
drwxr-xr-x    3 root     root          1024 Mar  9  2018 home
lrwxrwxrwx    1 root     root             7 Mar  9  2018 lib -> usr/lib
drwx------    2 root     root         12288 Dec  8 09:16 lost+found
drwxr-xr-x    2 root     root          1024 Mar  9  2018 media
drwxr-xr-x    2 root     root          1024 Mar  9  2018 mnt
dr-xr-xr-x  173 root     root             0 Dec  8 09:16 proc
drwx------    3 root     root          1024 Dec  8 09:16 root
drwxr-xr-x   11 root     root           320 Dec  8 09:16 run
lrwxrwxrwx    1 root     root             8 Mar  9  2018 sbin -> 
usr/sbin
drwxr-xr-x    2 root     root          1024 Mar  9  2018 srv
dr-xr-xr-x   12 root     root             0 Dec  8 09:16 sys
drwxrwxrwt    9 root     root           180 Dec  8 09:16 tmp
drwxr-xr-x   10 root     root          1024 Mar  9  2018 usr
drwxr-xr-x   10 root     root          1024 Dec  8 09:16 var
root@qemux86-64:/# cd /var/
root@qemux86-64:/var# ls -al
drwxr-xr-x   10 root     root          1024 Dec  8 09:16 .
drwxr-xr-x   17 root     root          1024 Dec  8 09:16 ..
-rw-r--r--    1 root     root           208 Mar  9  2018 .updated
drwxr-xr-x    2 root     root          1024 Mar  9  2018 backups
drwxr-xr-x    4 root     root          1024 Dec  8 09:16 cache
drwxr-xr-x    6 root     root          1024 Dec  8 09:16 lib
drwxr-xr-x    2 root     root          1024 Mar  9  2018 local
lrwxrwxrwx    1 root     root            11 Mar  9  2018 lock -> 
../run/lock
drwxr-xr-x    4 root     root          1024 Dec  8 09:16 log
lrwxrwxrwx    1 root     root             6 Mar  9  2018 run -> ../run
drwxr-xr-x    3 root     root          1024 Mar  9  2018 spool
drwxrwxrwt    5 root     root          1024 Dec  8 09:16 tmp
drwxrwxrwt    2 root     root            40 Dec  8 09:16 volatile
root@qemux86-64:/var# mount | grep tmpfs
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=1012164k,nr_inodes=253041,mode=755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run type tmpfs 
(rw,nosuid,nodev,size=405732k,nr_inodes=819200,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs 
(ro,nosuid,nodev,noexec,size=4096k,nr_inodes=1024,mode=755)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,nr_inodes=1048576)
tmpfs on /var/volatile type tmpfs (rw,relatime)
root@qemux86-64:/var#

5.
SysVinit
VOLATILE_TMP_DIR="yes"
VOLATILE_LOG_DIR="no"

root@qemux86-64:/# ls -al
drwxr-xr-x   17 root     root          1024 Dec  8 09:40 .
drwxr-xr-x   17 root     root          1024 Dec  8 09:40 ..
drwxr-xr-x    2 root     root          3072 Mar  9  2018 bin
drwxr-xr-x    2 root     root          1024 Mar  9  2018 boot
drwxr-xr-x   13 root     root          2960 Dec  8 09:40 dev
drwxr-xr-x   20 root     root          1024 Dec  8 09:40 etc
drwxr-xr-x    3 root     root          1024 Mar  9  2018 home
drwxr-xr-x    6 root     root          1024 Mar  9  2018 lib
drwx------    2 root     root         12288 Dec  8 09:40 lost+found
drwxr-xr-x    2 root     root          1024 Mar  9  2018 media
drwxr-xr-x    2 root     root          1024 Mar  9  2018 mnt
dr-xr-xr-x  159 root     root             0 Dec  8 09:40 proc
drwxr-xr-x    4 root     root           240 Dec  8 09:40 run
drwxr-xr-x    2 root     root          3072 Mar  9  2018 sbin
dr-xr-xr-x   12 root     root             0 Dec  8 09:40 sys
lrwxrwxrwx    1 root     root             8 Dec  8 09:40 tmp -> /var/tmp
drwxr-xr-x    9 root     root          1024 Mar  9  2018 usr
drwxr-xr-x    9 root     root          1024 Dec  8 09:40 var
root@qemux86-64:/# cd /var/
root@qemux86-64:/var# ls -al
drwxr-xr-x    9 root     root          1024 Dec  8 09:40 .
drwxr-xr-x   17 root     root          1024 Dec  8 09:40 ..
drwxr-xr-x    2 root     root          1024 Mar  9  2018 backups
drwxr-xr-x    2 root     root          1024 Mar  9  2018 cache
drwxr-xr-x    4 root     root          1024 Mar  9  2018 lib
drwxr-xr-x    2 root     root          1024 Mar  9  2018 local
lrwxrwxrwx    1 root     root             9 Dec  8 09:40 lock -> 
/run/lock
drwxr-xr-x    2 root     root          1024 Dec  8 09:40 log
lrwxrwxrwx    1 root     root             4 Dec  8 09:40 run -> /run
drwxr-xr-x    2 root     root          1024 Mar  9  2018 spool
lrwxrwxrwx    1 root     root            17 Dec  8 09:40 tmp -> 
/var/volatile/tmp
drwxrwxrwt    3 root     root            60 Dec  8 09:40 volatile
root@qemux86-64:/var# mount | grep tmp
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=1012164k,nr_inodes=253041,mode=755)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime)
root@qemux86-64:/var#


6.
systemd
VOLATILE_TMP_DIR="no"
VOLATILE_LOG_DIR="yes"

root@qemux86-64:/# ls -al
drwxr-xr-x   17 root     root          1024 Dec  8 09:46 .
drwxr-xr-x   17 root     root          1024 Dec  8 09:46 ..
lrwxrwxrwx    1 root     root             7 Mar  9  2018 bin -> usr/bin
drwxr-xr-x    2 root     root          1024 Mar  9  2018 boot
drwxr-xr-x   14 root     root          3260 Dec  8 09:46 dev
drwxr-xr-x   21 root     root          3072 Dec  8 09:46 etc
drwxr-xr-x    3 root     root          1024 Mar  9  2018 home
lrwxrwxrwx    1 root     root             7 Mar  9  2018 lib -> usr/lib
drwx------    2 root     root         12288 Dec  8 09:44 lost+found
drwxr-xr-x    2 root     root          1024 Mar  9  2018 media
drwxr-xr-x    2 root     root          1024 Mar  9  2018 mnt
dr-xr-xr-x  173 root     root             0 Dec  8 09:46 proc
drwx------    3 root     root          1024 Dec  8 09:46 root
drwxr-xr-x   11 root     root           320 Dec  8 09:46 run
lrwxrwxrwx    1 root     root             8 Mar  9  2018 sbin -> 
usr/sbin
drwxr-xr-x    2 root     root          1024 Mar  9  2018 srv
dr-xr-xr-x   12 root     root             0 Dec  8 09:46 sys
drwxrwxrwt    9 root     root           180 Dec  8 09:46 tmp
drwxr-xr-x   10 root     root          1024 Mar  9  2018 usr
drwxr-xr-x    9 root     root          1024 Dec  8 09:46 var
root@qemux86-64:/# cd /var/
root@qemux86-64:/var# ls -al
drwxr-xr-x    9 root     root          1024 Dec  8 09:46 .
drwxr-xr-x   17 root     root          1024 Dec  8 09:46 ..
-rw-r--r--    1 root     root           208 Mar  9  2018 .updated
drwxr-xr-x    2 root     root          1024 Mar  9  2018 backups
drwxr-xr-x    4 root     root          1024 Dec  8 09:46 cache
drwxr-xr-x    6 root     root          1024 Dec  8 09:46 lib
drwxr-xr-x    2 root     root          1024 Mar  9  2018 local
lrwxrwxrwx    1 root     root            11 Mar  9  2018 lock -> 
../run/lock
lrwxrwxrwx    1 root     root            12 Mar  9  2018 log -> 
volatile/log
lrwxrwxrwx    1 root     root             6 Mar  9  2018 run -> ../run
drwxr-xr-x    3 root     root          1024 Mar  9  2018 spool
drwxrwxrwt    5 root     root          1024 Dec  8 09:46 tmp
drwxrwxrwt    3 root     root            60 Dec  8 09:46 volatile
root@qemux86-64:/var# mount | grep tmp
devtmpfs on /dev type devtmpfs 
(rw,relatime,size=1012164k,nr_inodes=253041,mode=755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run type tmpfs 
(rw,nosuid,nodev,size=405732k,nr_inodes=819200,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs 
(ro,nosuid,nodev,noexec,size=4096k,nr_inodes=1024,mode=755)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,nr_inodes=1048576)
tmpfs on /var/volatile type tmpfs (rw,relatime)
root@qemux86-64:/var#

Changqing Li (5):
   bitbake.conf: set correct FILESYSTEM_PERMS_TABLES
   base-files: update dirs1777 and volatiles according to
     VOLATILE_TMP_DIR
   initscripts: support persistent tmp
   systemd: support persistent tmp
   eudev: create dir /tmp if persistent tmp is used

  meta/conf/bitbake.conf                        |  5 ++-
  ...fs-perms.txt => fs-perms-volatile-log.txt} | 32 -------------------
  ...tent-log.txt => fs-perms-volatile-tmp.txt} | 27 ----------------
  meta/files/fs-perms.txt                       |  3 --
  .../base-files/base-files_3.0.14.bb           |  8 +++--
  .../initscripts/initscripts-1.0/volatiles     |  1 +
  .../initscripts/initscripts_1.0.bb            | 12 ++++---
  .../systemd/systemd/00-create-volatile.conf   |  3 +-
  meta/recipes-core/systemd/systemd_254.4.bb    | 23 +++++++++----
  meta/recipes-core/udev/eudev_3.2.14.bb        |  4 +++
  10 files changed, 40 insertions(+), 78 deletions(-)
  copy meta/files/{fs-perms.txt => fs-perms-volatile-log.txt} (53%)
  rename meta/files/{fs-perms-persistent-log.txt => 
fs-perms-volatile-tmp.txt} (59%)








--
# Randy MacLeod
# Wind River Linux
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