Date:   Tue, 21 Mar 2023 17:19:18 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     Yangtao Li <frank.li@vivo.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>,
        Iurii Zaikin <yzaikin@google.com>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH] fs/drop_caches: move drop_caches sysctls into its own
 file
Message-ID: <ZBnnFtKVgAFQ4yeo@casper.infradead.org>
References: <20230321130908.6972-1-frank.li@vivo.com>
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 <ZBnho5yPbXIQs752@bombadil.infradead.org>
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On Tue, Mar 21, 2023 at 09:56:03AM -0700, Luis Chamberlain wrote:
> On Tue, Mar 21, 2023 at 04:42:32PM +0000, Matthew Wilcox wrote:
> > On Tue, Mar 21, 2023 at 09:09:07PM +0800, Yangtao Li wrote:
> > > +static struct ctl_table drop_caches_table[] = {
> > > +	{
> > > +		.procname	= "drop_caches",
> > > +		.data		= &sysctl_drop_caches,
> > > +		.maxlen		= sizeof(int),
> > > +		.mode		= 0200,
> > > +		.proc_handler	= drop_caches_sysctl_handler,
> > > +		.extra1		= SYSCTL_ONE,
> > > +		.extra2		= SYSCTL_FOUR,
> > > +	},
> > > +	{}
> > > +};
> > 
> > Could we avoid doing this until we no longer need an entire zero entry
> > after the last one? 
> 
> That may be 2-3 kernel release from now. The way to use ARRAY_SIZE()
> really is to deprecate the crap APIs that allow messy directory sysctl
> structures.

I'm OK with waiting another year to commence this cleanup.  We've lived
with the giant tables for decades already.  Better to get the new API
right than split the tables now, then have to touch all the places
again.