/tmp not wiping on boot

[printf]

Noticed, that my /tmp directory never gets wiped.
I have the default /etc/conf.d/bootmisc settings:

Code: Select all

# List of /tmp directories we should clean up
clean_tmp_dirs="/tmp"

# Should we wipe the tmp paths completely or just selectively remove known
# locks / files / etc... ?
wipe_tmp="YES"

# Write the initial dmesg log into /var/log/dmesg after boot
# This may be useful if you need the kernel boot log afterwards
log_dmesg="YES"

# Save the previous dmesg log to dmesg.old
# This may be useful if you need to compare the current boot to the
# previous one.
#previous_dmesg=no

bootmisc is correctly enabled:

Code: Select all

Runlevel: boot
 hwclock                                                                       [  started  ]
 modules                                                                       [  started  ]
 fsck                                                                          [  started  ]
 root                                                                          [  started  ]
 mtab                                                                          [  started  ]
 swap                                                                          [  started  ]
 localmount                                                                    [  started  ]
 sysctl                                                                        [  started  ]
 bootmisc                                                                      [  started  ]
 elogind                                                                       [  started  ]
 termencoding                                                                  [  started  ]
 save-termencoding                                                             [  started  ]
 procfs                                                                        [  started  ]
 hostname                                                                      [  started  ]
 loopback                                                                      [  started  ]
 keymaps                                                                       [  started  ]
 save-keymaps                                                                  [  started  ]
 binfmt                                                                        [  started  ]
 seedrng                                                                       [  started  ]
 systemd-tmpfiles-setup                                                        [  started  ]

The only thing, that is a bit out of ordinary is my fstab because:

• I use a notebook with an SSD in it's only slot
• I like to reduce SSD wear, so I also have a HDD, as an USB drive
• sometimes the external HDD does not get recognized on boot, so i set up a mechanism in fstab, where I mount az 1MB tmpfs as the heavy-write directories so I don't accidentally cause unnecessary wear to the SSD

The important parts of the fstab:

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#ssd
#/dev/sda1 - bootloader
PARTLABEL=boot                  /boot                   vfat    defaults,noatime                        0 2
PARTLABEL=rootfs                /                       ext4    defaults,noatime,discard                0 1
PARTLABEL=home                  /home                   ext4    defaults,noatime,discard                0 2

#tmpfs                          /tmp                    tmpfs   nodev,nosuid,size=1G                    0 0
#workarnoud: do not write to disk
tmpfs                           /tmp                    tmpfs   nodev,nosuid,size=2G                    0 0
tmpfs                           /var/tmp                tmpfs   noatime,size=1M                         0 0
tmpfs                           /usr/portage            tmpfs   noatime,size=1M                         0 0
tmpfs                           /usr/src                tmpfs   noatime,size=1M                         0 0

#hdd - support
PARTLABEL=swap                  none                    swap    sw                                      0 0
PARTLABEL=support               /mnt/support            ext4    defaults,noatime,discard                0 2
/mnt/support/tmp                /tmp                    none    defaults,bind                           0 0
/mnt/support/var_tmp            /var/tmp                none    defaults,bind                           0 0
/mnt/support/usr_portage        /usr/portage            none    defaults,bind                           0 0
/mnt/support/usr_src            /usr/src                none    defaults,bind                           0 0

Could this be because it gets mounted after bootmisc is executed? What else I am missing?

[user]

Overmount looks odd to me. Later fstab entry "wins" and you discard 2G memory for nothing.

Noticed, that my /tmp directory never gets wiped.

Code: Select all

...
tmpfs                           /tmp                    tmpfs   nodev,nosuid,size=2G                    0 0
...
PARTLABEL=support               /mnt/support            ext4    defaults,noatime,discard                0 2
/mnt/support/tmp                /tmp                    none    defaults,bind                           0 0
...

Why not using zram for /tmp to reduce HDD/SSD writes?

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# cat /etc/udev/rules.d/10-zram.rules 
KERNEL=="zram0", SUBSYSTEM=="block", DRIVER=="", ACTION=="add", ATTR{initstate}=="0", ATTR{comp_algorithm}="lz4", ATTR{disksize}="4G", RUN+="/sbin/mkfs.ext4 -O fast_commit,inline_data,^metadata_csum,^has_journal,^resize_inode,^dir_nlink,^huge_file -m 0 -L $name $env{DEVNAME}"

# cat /etc/fstab
/dev/zram0                                         /tmp                    ext4     discard,nobarrier,nodelalloc,nombcache,dioread_nolock,nodev,nosuid,noatime,user_xattr,acl 0 0

# zramctl zram0
NAME       ALGORITHM DISKSIZE   DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lz4             4G 522.7M 24.2M 31.4M       2 /tmp

No need to wipe after reboot, as mountpoint is in-memory filesystem.

[grknight]

you discard 2G memory for nothing.

This is not how tmpfs works. It only allocates when used not at mount time.