Re: [PATCH 2/2] fix file counting

[Andrew Morton <akpm@osdl.org>]

Dipankar Sarma <dipankar@in.ibm.com> wrote:
>
>  On Sat, Feb 18, 2006 at 01:45:29AM -0800, Andrew Morton wrote:
>  > Dipankar Sarma <dipankar@in.ibm.com> wrote:
>  > >
>  > > 
>  > >  Slight optimization -
>  > > 
>  > >  	if (get_nr_files() >= files_stat.max_files) {
>  > >  		if (capable(CAP_SYS_ADMIN)) {
>  > >  		/*
>  > >  		 * percpu_counters are inaccurate.  Do an expensive check before
>  > >  		 * we go and fail.
>  > >  		 */
>  > >  			if (percpu_counter_sum(&nr_files) >= 
>  > >  						files_stat.max_files)
>  > >  				goto over;
>  > >  		} else 
>  > >  			goto over;
>  > >  	}
>  > 
>  > That changes the behaviour for root.  Maybe you meant !capable(), but that
>  > still changes the behaviour.  I'm all confused.
> 
>  Hmm.. on second thoughts, there is no harm doing the expensive check
>  for both priviledged and non-priviledged user. It will correctly
>  allow non-priviledged users to create the new file provided
>  the fast-path percpu counter value returned was greater than the 
>  slow path per-cpu counter value.

Look closer ;)

	if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
		/*
		 * percpu_counters are inaccurate.  Do an expensive check before
		 * we go and fail.
		 */
		if (percpu_counter_sum(&nr_files) >= files_stat.max_files)
			goto over;
	}

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