On Thu, 27 Oct 2016, Fenghua Yu wrote:

> On Wed, Oct 26, 2016 at 04:45:50PM +0200, Thomas Gleixner wrote:
> > On Sat, 22 Oct 2016, Fenghua Yu wrote:
> > > +/*
> > > + * Forcibly remove all of subdirectories under root.
> > > + */
> > > +static void rmdir_all_sub(void)
> > > +{
> > > +	kernfs_remove(kn_info);
> > 
> > What clears kn_info?
> 
> Is the question "Why clears kn_info?"
> 
> kn_info is created during mount time and has different contents
> under "info" directory with CDP enabled or disabled by mount parameter "cdp".
> 
> umount needs to remove kn_info so that it's ready to be created next time
> during mount time. So user can do CAT mount, check "info", umount, and then
> CDP mount, check "info". The user will see different contents in two "info"
> checks.

Lemme rephrase. What does: kn_info = NULL; ?

We should clear static variables for correctness sake. The current code has
no problem with that, but 5 month down the road something is going to trip
over the stale reference.

Thanks,

	tglx