From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB138C33C99 for ; Wed, 8 Jan 2020 03:00:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B5DB20848 for ; Wed, 8 Jan 2020 03:00:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726149AbgAHDAQ (ORCPT ); Tue, 7 Jan 2020 22:00:16 -0500 Received: from fieldses.org ([173.255.197.46]:53894 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725812AbgAHDAP (ORCPT ); Tue, 7 Jan 2020 22:00:15 -0500 Received: by fieldses.org (Postfix, from userid 2815) id 2AD691C81; Tue, 7 Jan 2020 22:00:15 -0500 (EST) Date: Tue, 7 Jan 2020 22:00:15 -0500 From: "J. Bruce Fields" To: Chris Down Cc: "Darrick J. Wong" , linux-fsdevel@vger.kernel.org, Al Viro , Jeff Layton , Johannes Weiner , Tejun Heo , linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] fs: inode: Reduce volatile inode wraparound risk when ino_t is 64 bit Message-ID: <20200108030015.GB5476@fieldses.org> References: <20191220024936.GA380394@chrisdown.name> <20191220213052.GB7476@magnolia> <20191221101652.GA494948@chrisdown.name> <20200107173530.GC944@fieldses.org> <20200107174407.GA666424@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200107174407.GA666424@chrisdown.name> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jan 07, 2020 at 05:44:07PM +0000, Chris Down wrote: > J. Bruce Fields writes: > >I thought that (dev, inum) was supposed to be unique from creation to > >last unlink (and last close), and (dev, inum, generation) was supposed > >to be unique for all time. > > Sure, but I mean, we don't really protect against even the first case. > > >>I didn't mention generation because, even though it's set on tmpfs > >>(to prandom_u32()), it's not possible to evaluate it from userspace > >>since `ioctl` returns ENOTTY. We can't ask userspace applications to > >>introspect on an inode attribute that they can't even access :-) > > > >Is there any reason not to add IOC_GETVERSION support to tmpfs? > > > >I wonder if statx should return it too? > > We can, but that seems like a tangential discussion/patch series. > For the second case especially, that's something we should do > separately from this patchset, Oh, of course, I'm not objecting to this patchset at all, it's a "why not also do this?" question. > since this demonstrably fixes issues encountered in production, and > extending a user-facing APIs is likely to be a much more extensive > discussion. Though if it's a question of just a new implementation of an existing ioctl, I doubt it's such a big deal. (Not that I'm volunteering to write the patch.) --b.