Re: Default size limits for /run (/var/run) and /run/lock (/var/lock)

[Marvin Renich <mrvn@renich.org>]

* Luca Capello <luca@pca.it> [110414 06:43]:
> Hi there!
> 
> Disclaimer: this is my last post on this matter (i.e. the meaning of
> RAMLOCK), it seems there is a problem with myself or my understanding.
> 
> Either I do not read `man rcS` as you read it or we do not understand
> each other, so here the situation before and after your patch for /run
> (/var/lock became useless, everything is in /run/lock now, but I kept
> using /var/lock for consistency with the previous state):
> 
> [before] RAMLOCK=no  -> /var/lock on the same filesystem /var is on
>          RAMLOCK=yes -> /var/lock on tmpfs
>  [after] RAMLOCK=no  -> /var/lock is on tmpfs, shared with /run (given
>                         that /var/lock is symlinked/bind-mounted to
>                         /run/lock)
>          RAMLOCK=yes -> /var/lock gets its own tmpfs, differently from
>                         the one mounted at /run
> 
> So, the meaning of RAMLOCK, WRT `man rcS` and as I read it, *has*
> changed.  This is where we do not agree on wordings, but given that
> English is not my mother language, maybe it is only my fault.
> 
> Thx, bye,
> Gismo / Luca

Luca,

It appears to me that you understand perfectly what RAMLOCK does.  Your
issue appears to be with the wording of the man page.  To me (as a
native English speaker) the wording is explicit about what will happen
if you set RAMLOCK=yes (i.e. a tmpfs will be allocated and mounted at
/var/lock--soon to be /run/lock), but is ambiguous as to what will
happen if RAMLOCK=no.  The implicit meaning is that no tmpfs will be
allocated _for /var/lock_ and it will be on the same file system as
/var, whatever that may be (soon to be /run/lock and /run).  So the
implicit behavior is that if RAMLOCK=no, and /var is a tmpfs, /var/lock
will simply be a part of the tmpfs on /var.  This is indeed the current
(pre-/run) behavior, and is exactly the same as what will soon be with
/run.

The current wording of the man page seems correct to me, even for the
new /run directory structure (with appropriate changes from /var/lock to
/run/lock), but some minor changes in wording would make the RAMLOCK=no
behavior more explicit.  I would add the word "separate" and a sentence
describing the behavior when RAMLOCK=no:

    Make /var/lock/ available as a separate ram file system (tmpfs).
    Will also disable cleaning of /var/lock/ during boot.  Set to 'yes'
    to enable, to 'no' to disable.  When 'no', /var/lock is on the same
    file system as /var.  The size of the tmpfs can be controlled using
    TMPFS_SIZE and LOCK_SIZE in /etc/default/tmpfs.  Because of this,
    packages can not expect directories in /var/lock to exist after
    boot.  Packages expecting this are buggy and need to be fixed.

If you like this wording, you should file a wishlist bug on the
initscripts package.  (I'm not going to because the current wording
doesn't bother me.)

...Marvin