Re: [PATCH 2/2] fix file counting

From: Dipankar Sarma <dipankar@in.ibm.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, paulmck@us.ibm.com, dada1@cosmosbay.com
Subject: Re: [PATCH 2/2] fix file counting
Date: Sat, 18 Feb 2006 15:36:29 +0530	[thread overview]
Message-ID: <20060218100629.GQ29846@in.ibm.com> (raw)
In-Reply-To: <20060218014529.5f160d39.akpm@osdl.org>

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.

Just ignore my comment in the previous mail.

Thanks
Dipankar