[Bug 525154] Re: mountall for /var or other nfs mount races with rpc.statd

[Brian J. Murrell]

On 11-07-18 04:27 PM, Steve Langasek wrote:
> 
> This appears to be bug #523484.
> 
> To the best of my understanding, this describes a feature that is missing

Uhm, not so much "missing" as "broken".

> when using a separate /var (the ureadahead job will run but not do anything
> useful).

It's not even that nice.  What it will do is litter the boot with error
messages, which is annoying and distracting at best and a red herring
when there are other upstart/mountall bugs, at worst.

A first time admin of a system with a separate /var sees these errors on
boot, and even if he is lucky enough that boot succeeds, is still
concerned about the errors (if he is any good) and wastes time chasing
them down only to find that they are a bug that exists and has not and
will not be fixed.  Not very classy.

> This is certainly a bug, but not something that we are likely to
> backport to lucid even when a fix becomes available.

So instead you let the above situation continue on ad infinitum,
confusing new users?

> I think you would be
> hard pressed to convince any of the Ubuntu developers that it has a major
> impact on the usability of Ubuntu that systems with a separate /var don't
> get the boot speed enhancement from ureadahead!

It's not even the boot speed enhancement that is the issue.  It's the
emission of spurious errors that any good admin will have to waste time
chasing down.

> Also, you say that people have posted solutions; I've reviewed the bug log
> and there are no solutions to the bug there.  Most of the proposals would
> work *only* on systems with detached /var, so are not suitable for
> inclusion in the distribution;

Surely they are a good start though, with some conditional code needing
added to test for that separate /var case.

> So I'm afraid I regard this bug's current prioritization as "medium" to be
> correct, sorry.  Patches welcome, but I think it's unlikely that this is
> going to be worked on soon otherwise.

Exactly my point and the point of mine (and others') frustration.  You
guys let a bug get out into the wild by not testing a use-case that is
and/or should be very common in the server use space and now that it's
out there, you are just letting it ride.

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https://bugs.launchpad.net/bugs/525154

Title:
  mountall for /var or other nfs mount races with rpc.statd

Status in “mountall” package in Ubuntu:
  Invalid
Status in “nfs-utils” package in Ubuntu:
  Fix Released
Status in “portmap” package in Ubuntu:
  Fix Released
Status in “mountall” source package in Lucid:
  Invalid
Status in “nfs-utils” source package in Lucid:
  Fix Released
Status in “portmap” source package in Lucid:
  Fix Released
Status in “mountall” source package in Maverick:
  Invalid
Status in “nfs-utils” source package in Maverick:
  Fix Released
Status in “portmap” source package in Maverick:
  Fix Released
Status in “mountall” source package in Natty:
  Invalid
Status in “nfs-utils” source package in Natty:
  Fix Released
Status in “portmap” source package in Natty:
  Fix Released

Bug description:
  If one has /var (or /var/lib or /var/lib/nfs for that matter) on its
  own filesystem the statd.conf start races with the mounting of /var as
  rpc.statd needs /var/lib/nfs to be available in order to work.

  I am sure this is not the only occurrence of this type of problem.

  A knee-jerk solution is to simply spin in statd.conf waiting for
  /var/lib/nfs to be available, but polling sucks, especially for
  something like upstart whose whole purpose is to be an event driven
  action manager.

  SRU justification: NFS mounts do not start reliably on boot in lucid
  and maverick (depending on the filesystem layout of the client system)
  due to race conditions in the startup of statd.  This should be fixed
  so users of the latest LTS can make reliable use of NFS.

  Regression potential:  Some systems may fail to mount NFS filesystems
  at boot time that didn't fail before.  Some systems may hang at boot.
  Some systems may hang while upgrading the packages (this version or in
  a future SRU).  I believe the natty update adequately guards against
  all of these possibilities, but the risk is there.

  TEST CASE:
  1. Configure a system with /var as a separate partition.
  2. Add one or more mounts of type 'nfs' to /etc/fstab.
  3. Boot the system.
  4. Verify whether statd has started (status statd) and whether all NFS filesystems have been mounted.
  5. Repeat 3-4 until the race condition is triggered.
  6. Upgrade to the new version of portmap and nfs-common from -proposed.
  7. Repeat steps 3-4 until satisfied that statd now starts reliably and all non-gss-authenticated NFSv3 filesystems mount correctly at boot time.

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