[Bug 750371] [NEW] squid causing /var to stay busy during shutdown

[ryokenau]

Public bug reported:

Binary package hint: squid

I'm running Ubuntu 10.04.2 LTS with latest version of squid
2.7.STABLE7-1ubuntu12.2. This is a default install - there have been no
changes to /etc/squid.conf.

When I shutdown or reboot the system, I get the following error:

 * Unmounting local filesystems...
umount2: Device or resource busy
umount: /var: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
umount2: Device or resource busy
umount2: Device or resource busy
umount: /dev/mapper/vg01-usr busy - remounted read-only
        [fail]

When the system starts up again, I can see the following message:

/dev/mapper/vg01-var: recovering journal

It appears the /var partition was not cleanly unmounted during shutdown.
Obviously, there is a risk of filesystem corruption here. FYI, i have
/var and other important mountpoints as separate partitions (using LVM
and ext4).

To confirm my suspicions of squid still running during shutdown, I
checked /var/log/squid/cache.log and there is no indication that it
received the signal to terminate. In fact, cache.log hints at this
problem while the system is being brought up again:

Rebuilding storage in /var/spool/squid (DIRTY)

Only when I manually run "stop squid", then cache.log would report that
squid stopped successfully:

Preparing for shutdown after 0 requests
Waiting 30 seconds for active connections to finish
FD 14 Closing HTTP connection
Shutting down...
FD 15 Closing ICP connection
Closing unlinkd pipe FD 12
... <skipped> ...
logfileClose: closing log /var/log/squid/store.log
logfileClose: closing log /var/log/squid/access.log
Squid Cache (Version 2.7.STABLE7): Exiting normally.

To test whether /var was locked by squid during shutdown, I added a
script to run "ls /var/run | grep squid" and "lsof | grep var" before
filesystems are unmounted. And voila!

ls /var/run | grep squid:
squid.pid

lsof | grep var:
squid	971 proxy	cwd	DIR	251,4	 4096 130613	/var/spool/squid
squid	971 proxy	5u	REG	251,4	13617 128678	/var/log/squid/cache.log
squid	971 proxy	7w	REG	251,4	    0 128724	/var/log/squid/access.log
squid	971 proxy	9w	REG	251,4	    0 128789	/var/log/squid/store.log
squid	971 proxy	11w	REG	251,4	   48 130308	/var/spool/squid/swap.state

Hence, the next system startup would result in /var recovering journal
again.

Finally, I tried running "stop squid" before issuing the shutdown
command and it successfully unmounts /var and I do not get /var
recovering journal on the next system startup.

** Affects: squid (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/750371

Title:
  squid causing /var to stay busy during shutdown