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 D7C70C282DD for ; Tue, 7 Jan 2020 21:07:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3A3C24656 for ; Tue, 7 Jan 2020 21:07:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729544AbgAGVH3 (ORCPT ); Tue, 7 Jan 2020 16:07:29 -0500 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:39024 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729513AbgAGVHX (ORCPT ); Tue, 7 Jan 2020 16:07:23 -0500 Received: from dread.disaster.area (pa49-180-68-255.pa.nsw.optusnet.com.au [49.180.68.255]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 9EC533A3117; Wed, 8 Jan 2020 08:07:17 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1iow4J-0005jX-QL; Wed, 08 Jan 2020 08:07:15 +1100 Date: Wed, 8 Jan 2020 08:07:15 +1100 From: Dave Chinner To: Amir Goldstein Cc: Hugh Dickins , Chris Down , Linux MM , Andrew Morton , Al Viro , Matthew Wilcox , Jeff Layton , Johannes Weiner , Tejun Heo , linux-fsdevel , linux-kernel , kernel-team@fb.com Subject: Re: [PATCH v5 2/2] tmpfs: Support 64-bit inums per-sb Message-ID: <20200107210715.GQ23195@dread.disaster.area> References: <20200107001039.GM23195@dread.disaster.area> <20200107001643.GA485121@chrisdown.name> <20200107003944.GN23195@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=X6os11be c=1 sm=1 tr=0 a=sbdTpStuSq8iNQE8viVliQ==:117 a=sbdTpStuSq8iNQE8viVliQ==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=Jdjhy38mL1oA:10 a=1XWaLZrsAAAA:8 a=7-415B0cAAAA:8 a=qLVrV9dGIdnuQ3zi2hkA:9 a=jPg9kqVogik6UUPB:21 a=Tmguthn7wsSX_SwC:21 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 07, 2020 at 12:12:00PM +0200, Amir Goldstein wrote: > On Tue, Jan 7, 2020 at 10:36 AM Hugh Dickins wrote: > > > > On Tue, 7 Jan 2020, Amir Goldstein wrote: > > > On Tue, Jan 7, 2020 at 2:40 AM Dave Chinner wrote: > > > > On Tue, Jan 07, 2020 at 12:16:43AM +0000, Chris Down wrote: > > > > > Dave Chinner writes: > > > > > > It took 15 years for us to be able to essentially deprecate > > > > > > inode32 (inode64 is the default behaviour), and we were very happy > > > > > > to get that albatross off our necks. In reality, almost everything > > > > > > out there in the world handles 64 bit inodes correctly > > > > > > including 32 bit machines and 32bit binaries on 64 bit machines. > > > > > > And, IMNSHO, there no excuse these days for 32 bit binaries that > > > > > > don't using the *64() syscall variants directly and hence support > > > > > > 64 bit inodes correctlyi out of the box on all platforms. > > > > Interesting take on it. I'd all along imagined we would have to resort > > to a mount option for safety, but Dave is right that I was too focused on > > avoiding tmpfs regressions, without properly realizing that people were > > very unlikely to have written such tools for tmpfs in particular, but > > written them for all filesystems, and already encountered and fixed > > such EOVERFLOWs for other filesystems. > > > > Hmm, though how readily does XFS actually reach the high inos on > > ordinary users' systems? > > > > Define 'ordinary' > I my calculations are correct, with default mkfs.xfs any inode allocated > from logical offset > 2TB on a volume has high ino bits set. > Besides, a deployment with more than 4G inodes shouldn't be hard to find. You don't need to allocate 4 billion inodes to get >32bit inodes in XFS - the inode number is an encoding of the physical location of the inode in the filesystem. Hence we just have to allocate the inode at a disk address higher than 2TB into the device and we overflow 32bits. e.g. make a sparse fs image file of 10TB, mount it, create 50 subdirs, then start creating zero length files spread across the 50 separate subdirectories. You should see >32bit inode numbers almost immediately. (i.e. as soon as we allocate inodes in AG 2 or higher) IOWs, there are *lots* of 64bit inode numbers out there on XFS filesystems.... Cheers, Dave. -- Dave Chinner david@fromorbit.com