Moving my /tmp directory to it's own partition, works great until reboot, starts in read-only

English Install/Boot/Login
1

I wanted to move my /tmp directory to it’s own partition, first I checked that the systemd tmpfs wasn’t being used, which it wasn’t.

changed to Init 1
I created a new xfs partition
mounted to a temporary mount under /foo
cp -apx /tmp/. /foo
umount /foo
mv /tmp /tmp.old
mkdir /tmp
chmod 1777 /tmp
change /etc/fstab with uuid of new /tmp partition
mount -a
df -h to see if it’s there and right partition, looks good
Init 5
sddm starts fine
login to kde everything is fine
reboot

Now it comes up in tty in read-only mode, I can remount to rw, rem out my fstab change and go back to old /tmp.

Any ideas why it won’t work on reboot?

2

Given an fstab entry like this:

/dev/disk/by-id/ata-XXXXX-part1  /tmp    ext4    defaults,noatime,acl,user_xattr 1 2

when you “stat” the /tmp directory, it should look like this:


 # stat /tmp
  File: /tmp
  Size: 36864           Blocks: 80         IO Block: 4096   directory
Device: 821h/2081d      Inode: 2           Links: 37
Access: (1777/drwxrwxrwt)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-06-03 16:57:13.896425268 +0200
Modify: 2019-06-03 17:02:03.629812111 +0200
Change: 2019-06-03 17:02:03.629812111 +0200
 Birth: -
 #

You could consider using the YaST Partitioner to move /tmp and, possibly, /var , off to their own partitions …
Documentation is here: <https://doc.opensuse.org/documentation/leap/reference/html/book.opensuse.reference/cha.expert_partitioner.html&gt;.
There’s some additional information here: <https://doc.opensuse.org/documentation/leap/startup/html/book.opensuse.startup/cha.install.html#sec.yast_install.partitioning&gt;.

3

I didn’t see anything in partitioner or the docs you linked about moving an existing /tmp. Before I did my almost successful attempt, I had actually tried partitioner and set a mount point to /tmp, I didn’t think it would work, because of the existing /tmp directory that is being used, and the text mode yast in init 1 gave me a ruby error when I tried to launch partitioner. It created the fstab entry but didn’t work at all, which is what I suspected to begin with.

Since most of the things I could find for moving directories followed the steps I outlined, including
https://www.suse.com/support/kb/doc/?id=7015338

So that’s what I did, though /tmp also needs the chmod.

As I said everything looks good with df -h, even the stat /tmp and everything is fine when I go to init 5, I can even hibernate and power back up completely fine. But on full reboot it comes up read-only with /tmp unmounted, if I remount the system with rw, and do a mount -a, then init 5, I’m all fine again using the new /tmp partition. I have run filesystem check on the new partition, it’s fine, I have also run smartdisk on the drive, it’s fine as well.

So what could cause it to be completely error free when doing mount -a, or power on from hibernate, but cause a problem on full reboot?

4

Looks like it doesn’t get mounted at all, but … normally ( on default install ) /tmp is a subvolume of btrfs, which gets mounted as a tmpfs.

5

Sorry I should have said, I set up my Tumbleweed as all xfs, so there is no btrfs in play. I checked to make sure before everything that it wasn’t tmpfs or setup by systemd to be tmpfs, since systemd doesn’t do it in fstab, and systemd tmp.mount was masked.

6

Ok fixed it, my last post made me think a bit more about systemd which I am still pretty weak on knowledge wise. The tmp.mount unit was masked probably for the default way opensuse handles /tmp with btrfs, I thought this would be fine, but masking, seems to be a hard off to /dev/null to any kind of mounting of /tmp, not just turning off systemd tmpfs /tmp. So I unmasked tmp.mount and now everything works and is mounted properly.

7

Yes, the systemd “tmp.mount” service, which doesn’t have a “.service” in the name, is quite surprising, especially when one takes a look at the “big (mount) picture”:


 # systemctl list-unit-files | grep -i 'mount'
proc-sys-fs-binfmt_misc.automount                                static         
-.mount                                                          generated      
dev-hugepages.mount                                              static         
dev-mqueue.mount                                                 static         
home.mount                                                       generated      
home01.mount                                                     generated      
proc-fs-nfsd.mount                                               static         
proc-sys-fs-binfmt_misc.mount                                    static         
srv.mount                                                        generated      
sys-fs-fuse-connections.mount                                    static         
sys-kernel-config.mount                                          static         
sys-kernel-debug.mount                                           static         
tmp.mount                                                        generated      
var-lib-machines.mount                                           static         
var-lib-nfs-rpc_pipefs.mount                                     static         
var-lock.mount                                                   static         
var-run.mount                                                    static         
var.mount                                                        generated      
dracut-mount.service                                             static         
dracut-pre-mount.service                                         static         
nfs-mountd.service                                               static         
systemd-remount-fs.service                                       static         
umount.target                                                    static         
 #

Taking a look at the “generated” services reveals:


 # systemctl status -- -.mount tmp.mount var.mount srv.mount home.mount home01.mount
● -.mount - Root Mount
   Loaded: loaded (/etc/fstab; generated; vendor preset: disabled)
   Active: active (mounted) since Thu 2019-06-06 08:03:24 CEST; 1h 50min ago
    Where: /
     What: /dev/sda1
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/-.mount

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

● tmp.mount - /tmp
   Loaded: loaded (/etc/fstab; generated; vendor preset: disabled)
   Active: active (mounted) since Thu 2019-06-06 08:03:27 CEST; 1h 50min ago
    Where: /tmp
     What: /dev/sdc1
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 754 ExecMount=/usr/bin/mount /dev/disk/by-id/ata-ST3500418AS_Z2AENPNG-part1 /tmp -t ext4 -o defaults,noatime>
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/tmp.mount

Jun 06 08:03:27 XXX systemd[1]: Mounting /tmp...
Jun 06 08:03:27 XXX systemd[1]: Mounted /tmp.

● var.mount - /var
   Loaded: loaded (/etc/fstab; generated; vendor preset: disabled)
   Active: active (mounted) since Thu 2019-06-06 08:03:27 CEST; 1h 50min ago
    Where: /var
     What: /dev/sdb1
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 688 ExecMount=/usr/bin/mount /dev/disk/by-id/ata-WDC_WD10EZEX-60M2NA0_WD-WCC3F5AYCJL7-part1 /var -t ext4 -o >
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/var.mount

Jun 06 08:03:27 XXX systemd[1]: Mounting /var...
Jun 06 08:03:27 XXX systemd[1]: Mounted /var.

● srv.mount - /srv
   Loaded: loaded (/etc/fstab; generated; vendor preset: disabled)
   Active: active (mounted) since Thu 2019-06-06 08:03:27 CEST; 1h 50min ago
    Where: /srv
     What: /dev/sdc2
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 686 ExecMount=/usr/bin/mount /dev/disk/by-id/ata-ST3500418AS_Z2AENPNG-part2 /srv -t ext4 -o defaults,noatime>
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/srv.mount

Jun 06 08:03:27 XXX systemd[1]: Mounting /srv...
Jun 06 08:03:27 XXX systemd[1]: Mounted /srv.

● home.mount - /home
   Loaded: loaded (/etc/fstab; generated; vendor preset: disabled)
   Active: active (mounted) since Thu 2019-06-06 08:03:27 CEST; 1h 50min ago
    Where: /home
     What: /dev/sdc3
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 690 ExecMount=/usr/bin/mount /dev/disk/by-id/ata-ST3500418AS_Z2AENPNG-part3 /home -t xfs -o defaults,noquota>
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/home.mount

Jun 06 08:03:27 XXX systemd[1]: Mounting /home...
Jun 06 08:03:27 XXX systemd[1]: Mounted /home.

● home01.mount - /home01
   Loaded: loaded (/etc/fstab; generated; vendor preset: disabled)
   Active: active (mounted) since Thu 2019-06-06 08:03:28 CEST; 1h 50min ago
    Where: /home01
     What: /dev/sdb2
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 692 ExecMount=/usr/bin/mount /dev/disk/by-id/ata-WDC_WD10EZEX-60M2NA0_WD-WCC3F5AYCJL7-part2 /home01 -t xfs ->
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/home01.mount

Jun 06 08:03:27 XXX systemd[1]: Mounting /home01...
Jun 06 08:03:28 XXX systemd[1]: Mounted /home01.
 #

Meaning that, if you move away from the default Btrfs system partition, you’ll have to remember to unmask the “*.mount” systemd services to enable the systemd mounts generated from “/etc/fstab” …

  • Or, install without setting up with a Btrfs system partition …