On 06/09/2013 11:42 AM, Matthew Garrett wrote:
On Sun, Jun 09, 2013 at 11:05:44AM -0400, Doug Ledford wrote:
> And really, we've spent more time on this thread than it would take
> Lennart to fix PA. Just a quick stat and check of uid before trying to
> remove the stale files and this would all go away. Sure, your stat and
> remove could race, but this is nothing more than a garbage collection
> process anyway, so who cares? We'll just get it next time.
"Stat and then open" is inherently open to race conditions.
Of course it is.
In this
specific case it probably doesn't realistically matter,
Exactly my point.
but it's not
behaviour that should be encouraged.
I would never encourage it in terms of suggesting people try to second
guess the kernel's rules and limitations. However, you can use such a
technique to weed out otherwise known to fail cases, at least in
instances like this where it is a garbage collection operation and
failure to guess properly is obviously far from critical.
The only way to know for certain
whether you're going to be able to open or unlink a file is to attempt
to open or unlink that file, and we shouldn't encourage people to think
otherwise.
Agreed.