[arch-projects] [initscripts][RFC] managing /tmp

[Dave Reisner]

On Wed, May 18, 2011 at 06:34:50PM +0200, Tom Gundersen wrote:
> Hi guys,
> 
> Thanks to all of you who answered my many previous RFC's, I will
> follow up on them with code soon :-)
> 
> In the last initscripts release I inedvertently introduced a bug where
> /tmp is not cleared on boot if it is mounted on a non-tmpfs drive (it
> was only cleared if it lived on the root partition). This lead to a
> long discussion in the bug report about possible use-cases for /tmp.
> Among other things it was requested that we should stop clearing /tmp
> or make it configurable. As always, I'm opposed to adding
> configuration options just for the sake of it, so I propose something
> different.
> 
> First of all, this is what I took away from the discussion:
> 
> 1) /tmp should always be mounted as tmpfs (there are some really
> obscure scenarios when it should not be (if you have individual files
> larger than 256GB on it))
> 2) if /tmp is not mounted as tmpfs it should always be cleared at boot
> 
> That said, some users disagree, and want to /tmp to be preserved on
> reboot. Usually I would deny such a request, but I figured it would
> actually simplify things, so why not. This is my proposal:
> 
> 1) We advice users to mount /tmp as tmpfs (possibly with the proviso
> that the partition they would normally have used for /tmp is turned
> into swap space, and the size option of /tmp is set to the size of the
> old partition), this could be added to the standard fstab if we wish.
> 2) We never touch /tmp at boot. This makes no difference if the users
> follow our advice.
> 3) If the user wants to mount /tmp as a different fs, we advice them
> to put "rm -rf /tmp/* /tmp/.*" in rc.local, or manage /tmp in any
> other way they want (e.g. by using the tmpwatch package).
> 
> What do you think?
> 
> Cheers,
> 
> Tom

Looking at the patch that triggered this, I'm confused as to why the
logic was added to rc.sysinit to begin with. Why conditionally check for
/tmp being mounted?  What's the harm in unconditionally calling rm -rf
/tmp/*? Has it bitten us in the past? The commit message doesn't even
cover this change.

dave