From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751444AbdBXUmw (ORCPT ); Fri, 24 Feb 2017 15:42:52 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:52702 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751219AbdBXUmq (ORCPT ); Fri, 24 Feb 2017 15:42:46 -0500 Date: Fri, 24 Feb 2017 20:42:27 +0000 From: Al Viro To: Peter Zijlstra Cc: Linus Torvalds , Chris Mason , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, David Howells , elena.reshetova@intel.com, ishkamiel@gmail.com, dwindsor@gmail.com, gregkh@linuxfoundation.org Subject: Re: [RFC][PATCH 00/10] On inode::i_count and the usage vs reference count issue Message-ID: <20170224204227.GN29622@ZenIV.linux.org.uk> References: <20170224154329.478276481@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170224154329.478276481@infradead.org> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 24, 2017 at 04:43:29PM +0100, Peter Zijlstra wrote: > There's a number of options here: > > - I'm not completely insane, and these patches can be made to work. > > - We decide usage-counts are useful and try and support them in refcount_t; > this has the down-side that people can more easily write bad code (by doing > from 0 increments that should not have happened). > > - We decide usage-counts need their own type (urgh, more...). > > - None of the above, we keep i_count as is and let people hunt and convert > actual refcounts. The last one; if some object has non-trivial lifetime rules, don't try to shoehorn it into refcount_t. VFS-side the same goes for struct dentry (non-trivial lifetime and locking rules) struct mount (per-CPU fun, barriers, etc.) struct super_block (non-trivial lifecycle and lifetime rules) I'm not sure if struct file is a good match, BTW - net/unix/garbage.c would be one place in need of a careful looking into if we went for it.