[systemd-devel] PrivateTmp and systemd-tmpfiles

[Peeters Simon]

2012/10/17 Lennart Poettering <lennart at poettering.net>:
> On Wed, 17.10.12 14:16, Lukáš Nykrýn (lnykryn at redhat.com) wrote:
>
>> Hello,
>> Today I have read this bug
>> https://bugzilla.redhat.com/show_bug.cgi?id=866693 and described
>> systemd-tmpfiles behavior look pretty wrong to me, but I am not sure how
>> to fix it. Some ideas cross my mind; moving systemd-namespace-*
>> elsewhere, adding some option to exclude dirs in tmpfiles conf files,
>> stop cleaning /tmp, hardcode some excludes to tmpfiles, but I don't like
>> any of these solutions.
>
> We already allow files to be excluded from clean up by setting the
> sticky bit on them. We can't do that for dirs however, since the sticky
> bit for dirs has a different meaning.

Maybe create a new (empty) file inside this dir (on creation of the
namespace) and set the sticky bit on it. This way tmpfiles will never
delete the dir because it is not empty.
Also everything needed when the service is stopped is removing this
file so tmpfiles can clean up next time it passes by.

> One possible way to solve this
> issue otherwise might be by introducing an xattr for this. The one thing
> blocking this right now however is that tmpfs still can't handle xattrs
> properly. There were multiple attempts to get xattrs for tmpfs into the
> kernel, not sure what the latest state on this is.
>
> The best would probably be to exclude these dirs from clean-up via
> explicit tmpfiles lines. Unfortunately "x" is probably not going to do
> it here, since we actually want recursive clean-up inside the dir, just
> not of the dir... So maybe introduce a new type of "X" that excludes the
> dir itself from clean-up but does not exclude recursively?

Simon Peeters