Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 28 Jun 2022 12:48:53 +0200
From:   Christian Brauner <brauner@kernel.org>
To:     Jan Kara <jack@suse.cz>
Cc:     Guowei Du <duguoweisz@gmail.com>, amir73il@gmail.com,
        repnop@google.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, duguowei <duguowei@xiaomi.com>
Subject: Re: [PATCH 6/6] fanotify: add current_user_instances node
Message-ID: <20220628104853.c3gcsvabqv2zzckd@wittgenstein>
References: <20220628101413.10432-1-duguoweisz@gmail.com>
 <20220628104528.no4jarh2ihm5gxau@quack3>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20220628104528.no4jarh2ihm5gxau@quack3>
Precedence: bulk

On Tue, Jun 28, 2022 at 12:45:28PM +0200, Jan Kara wrote:
> On Tue 28-06-22 18:14:13, Guowei Du wrote:
> > From: duguowei <duguowei@xiaomi.com>
> > 
> > Add a node of sysctl, which is current_user_instances.
> > It shows current initialized group counts of system.
> > 
> > Signed-off-by: duguowei <duguowei@xiaomi.com>
> 
> Hum, I'm not sure about a wider context here but the changelog is certainly
> missing a motivation of this change - why do you need this counter? In
> particular because we already do maintain (and limit) the number of
> fanotify groups each user has allocated in a particular namespace...

Yeah, that's pretty strange as there's
/proc/sys/user/max_fanotify_groups
/proc/sys/user/max_fanotify_marks
it could be to have a ro counter that allows to display the current
number of groups? But that seems strange as we don't expose that
information anywhere for similar things. What would this be used for
even?