New subject: Root file system skipped when mlocate (updatedb) is run via systemd timer

Monday, 2 August 2021

I have several binaries matching /usr/bin/myth*. When mlocate-updatedb 
runs via a timer, the / file system is skipped so no files under 
/usr/bin are listed when I run "locate bin/myth".

$ locate bin/myth
/home/mythtv/bin/mythconverg-create
/home/mythtv/bin/mythconverg-drop
/home/mythtv/bin/mythconverg-restore
/home/ulrick/bin/mythtv-status
/home/ulrick/bin/mythtv-upcoming-recordings
/home/usr/local/bin/mythbackend-testsched
/home/usr/local/bin/mythlink.pl
/home/usr/local/bin/mythtv-status
/home/usr/local/bin/mythtvfs
/home/usr/local/sbin/myth-purge-old-db-backups
/home/usr/local/sbin/mythconverg_backup.pl
/home/usr/local/sbin/mythconverg_restore.pl

If I run /usr/libexec/mlocate-run-updatedb manually from a superuser 
'bash' shell, the / file system is included so the expected files are 
listed by 'locate':

$ locate bin/myth
/home/mythtv/bin/mythconverg-create
/home/mythtv/bin/mythconverg-drop
/home/mythtv/bin/mythconverg-restore
/home/ulrick/bin/mythtv-status
/home/ulrick/bin/mythtv-upcoming-recordings
/home/usr/local/bin/mythbackend-testsched
/home/usr/local/bin/mythlink.pl
/home/usr/local/bin/mythtv-status
/home/usr/local/bin/mythtvfs
/home/usr/local/sbin/myth-purge-old-db-backups
/home/usr/local/sbin/mythconverg_backup.pl
/home/usr/local/sbin/mythconverg_restore.pl
/usr/bin/mytharchivehelper
/usr/bin/mythavtest
/usr/bin/mythbackend
/usr/bin/mythccextractor
/usr/bin/mythcommflag
/usr/bin/mythexternrecorder
/usr/bin/mythffmpeg
/usr/bin/mythffprobe
/usr/bin/mythfilerecorder
/usr/bin/mythfilldatabase
/usr/bin/mythfrontend
/usr/bin/mythjobqueue
/usr/bin/mythlcdserver
/usr/bin/mythmediaserver
/usr/bin/mythmetadatalookup
/usr/bin/mythpreviewgen
/usr/bin/mythpython
/usr/bin/mythreplex
/usr/bin/mythscreenwizard
/usr/bin/mythshutdown
/usr/bin/mythtranscode
/usr/bin/mythtv-setup
/usr/bin/mythtvsetup
/usr/bin/mythutil
/usr/bin/mythwelcome
/usr/bin/mythwikiscripts
/usr/bin/mythzmserver
/usr/local/bin/mythbackend-testsched
/usr/local/bin/mythlink.pl
/usr/local/bin/mythtv-status
/usr/local/bin/mythtvfs
/usr/local/sbin/myth-purge-old-db-backups
/usr/local/sbin/mythconverg_backup.pl
/usr/local/sbin/mythconverg_restore.pl

Relevant output and files:

# systemctl status mlocate-updatedb.timer
● mlocate-updatedb.timer - Updates mlocate database every day
      Loaded: loaded (/usr/lib/systemd/system/mlocate-updatedb.timer; 
enabled; vendor preset: enabled)
      Active: active (waiting) since Fri 2021-07-30 17:42:59 CDT; 2 days ago
     Trigger: Tue 2021-08-03 00:00:00 CDT; 13h left
    Triggers: ● mlocate-updatedb.service

Jul 30 17:42:59 calvin.home.du systemd[1]: Started Updates mlocate 
database…day.
Hint: Some lines were ellipsized, use -l to show in full.

# systemctl -l status mlocate-updatedb.service
● mlocate-updatedb.service - Update a database for mlocate
      Loaded: loaded (/usr/lib/systemd/system/mlocate-updatedb.service; 
static)
      Active: inactive (dead) since Mon 2021-08-02 00:00:01 CDT; 10h ago
TriggeredBy: ● mlocate-updatedb.timer
    Main PID: 63611 (code=exited, status=0/SUCCESS)
         CPU: 66ms

Aug 02 00:00:01 calvin.home.du systemd[1]: Started Update a database for 
mlocate.
Aug 02 00:00:01 calvin.home.du systemd[1]: mlocate-updatedb.service: 
Succeeded.

# cat /lib/systemd/system/mlocate-updatedb.timer
[Unit]
Description=Updates mlocate database every day

[Timer]
OnCalendar=daily
AccuracySec=24h
Persistent=true

[Install]
WantedBy=timers.target

# cat /lib/systemd/system/mlocate-updatedb.service
[Unit]
Description=Update a database for mlocate

[Service]
ExecStart=/usr/libexec/mlocate-run-updatedb
Nice=19
IOSchedulingClass=2
IOSchedulingPriority=7

PrivateTmp=true
PrivateDevices=true
PrivateNetwork=true
ProtectSystem=true

# cat /usr/libexec/mlocate-run-updatedb
#!/usr/bin/sh

nodevs=$(< /proc/filesystems awk '$1 == "nodev" && $2 !=
"rootfs" && $2 
!= "zfs" { print $2 }')
/usr/bin/updatedb -f "$nodevs"

Any thoughts? Have I discovered a bug with mlocate-updatedb.timer or 
mlocate-updatedb.service?

Thanks,
Dave