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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33605E7F154 for ; Thu, 28 Sep 2023 17:19:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BC2C48D00C3; Thu, 28 Sep 2023 13:19:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B717C8D00C0; Thu, 28 Sep 2023 13:19:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9C4138D00C3; Thu, 28 Sep 2023 13:19:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 8900B8D00C0 for ; Thu, 28 Sep 2023 13:19:51 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 5F05E8041B for ; Thu, 28 Sep 2023 17:19:51 +0000 (UTC) X-FDA: 81286668582.21.CB4B6EF Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf13.hostedemail.com (Postfix) with ESMTP id E6E5E2000A for ; Thu, 28 Sep 2023 17:19:48 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=ryWGGERq; spf=pass (imf13.hostedemail.com: domain of djwong@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=djwong@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1695921589; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=PqXMwusiHvvizfO8oKIjACeJyGingtoyq7hCWniGHas=; b=dm+pKAmpBj4sGIso1ieglaBbpWl/2vyG/RO3zjSo8UMq6rM83F7piOslDkC6lIPz3qsswZ wtouWZAOllYU2PSJ5ugD9o7q8Nvp4+7qsVrk8bA5Ty8k2t2GuOyyFwgoMrTSnZ/Y+BZg47 46jwx4EiV78mwaP+pgELTjxfPDbY6+0= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=ryWGGERq; spf=pass (imf13.hostedemail.com: domain of djwong@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=djwong@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1695921589; a=rsa-sha256; cv=none; b=q01qeU9wFXOtumndf+spUIc+2gjQPOjq2v9RKD11E9UKyonJD2ZGwq2VSZQ4bKgz1MwHRD mnHO0Yt/zZvsqGpt6ivap2itXcN/zIq6Dk2K/4eDOG4ZH7Inz+PfTmC83A+AlsndiyRoWC AyCxntSTa7e8HzZ+/E/NbvoCxsr6No8= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id C13F2CE2245; Thu, 28 Sep 2023 17:19:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE2E8C433C8; Thu, 28 Sep 2023 17:19:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695921584; bh=TBXriEELB328eOKqJ6NFSOrKvuSXYJvHz6sohZrQIx0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ryWGGERqf3ypGjqQYm5gVKZvkucKGUk0K4h6YIIWQ/NpKuXJi36HQDWjgdgtJd7wu TP/RvT38TPj/OA2Jk4aeD0DGoa7LAN7jIOlBWE0I1eYn6imAEKifbbeaG59NKi/slD aEVjDaHe+6Tji3j/v0JkIDO2dR6Fo6pHy84G4o5KxjxBslGp0LwydCJH4NJcX4DsY2 2+Ki57CRL6p89OjFpqSqXlcve39ZEqPDxD7QZyCHUVk8IqPpmvXHWivOQJXeNPWNjx piSViGDp1oRPgjAY21DvqURTHMn9e50dg1rgKW7SErtrbVvTXl75DArwoAJ6zoDjTa 8X72loIt6il5Q== Date: Thu, 28 Sep 2023 10:19:43 -0700 From: "Darrick J. Wong" To: Jeff Layton Cc: Arnd Bergmann , Alexander Viro , Christian Brauner , Linus Torvalds , David Sterba , Amir Goldstein , Theodore Ts'o , "Eric W. Biederman" , Kees Cook , Jeremy Kerr , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Mattia Dongili , Dennis Dalessandro , Jason Gunthorpe , Leon Romanovsky , Brad Warrum , Ritu Agarwal , Hans de Goede , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Mark Gross , Jiri Slaby , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , Christian Schoenebeck , David Sterba , David Howells , Marc Dionne , Ian Kent , Luis de Bethencourt , Salah Triki , "Tigran A. Aivazian" , Chris Mason , Josef Bacik , Xiubo Li , Ilya Dryomov , Jan Harkes , coda@cs.cmu.edu, Joel Becker , Christoph Hellwig , Nicolas Pitre , "Rafael J . Wysocki" , Ard Biesheuvel , Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Namjae Jeon , Sungjong Seo , Jan Kara , Andreas Dilger , Jaegeuk Kim , OGAWA Hirofumi , Christoph Hellwig , Miklos Szeredi , Bob Peterson , Andreas Gruenbacher , Richard Weinberger , Anton Ivanov , Johannes Berg , Mikulas Patocka , Mike Kravetz , Muchun Song , Jan Kara , David Woodhouse , Dave Kleikamp , Tejun Heo , Trond Myklebust , Anna Schumaker , Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Ryusuke Konishi , Anton Altaparmakov , Konstantin Komarov , Mark Fasheh , Joseph Qi , Bob Copeland , Mike Marshall , Martin Brandenburg , Luis Chamberlain , Iurii Zaikin , Tony Luck , "Guilherme G. Piccoli" , Anders Larsen , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Sergey Senozhatsky , Phillip Lougher , Steven Rostedt , Masami Hiramatsu , Evgeniy Dushistov , Chandan Babu R , Damien Le Moal , Naohiro Aota , Johannes Thumshirn , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Hugh Dickins , Andrew Morton , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-rdma@vger.kernel.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, v9fs@lists.linux.dev, linux-afs@lists.infradead.org, autofs@vger.kernel.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, codalist@coda.cs.cmu.edu, linux-efi@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, gfs2@lists.linux.dev, linux-um@lists.infradead.org, linux-mtd@lists.infradead.org, jfs-discussion@lists.sourceforge.net, linux-nfs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, ntfs3@lists.linux.dev, ocfs2-devel@lists.linux.dev, linux-karma-devel@lists.sourceforge.net, devel@lists.orangefs.org, linux-unionfs@vger.kernel.org, linux-hardening@vger.kernel.org, reiserfs-devel@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-trace-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, bpf@vger.kernel.org, Netdev , apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Subject: Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers Message-ID: <20230928171943.GK11439@frogsfrogsfrogs> References: <20230928110554.34758-1-jlayton@kernel.org> <20230928110554.34758-2-jlayton@kernel.org> <6020d6e7-b187-4abb-bf38-dc09d8bd0f6d@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: E6E5E2000A X-Rspam-User: X-Stat-Signature: f4mxrpcp5orr9mbe8zzwc1h7ybt6ejop X-Rspamd-Server: rspam01 X-HE-Tag: 1695921588-522341 X-HE-Meta: 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 88RiD1bA 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 H8d+85/R 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 L+kRe3Gt 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 /FSXhFSB qUuJfns9tRzzWljpdi3xrCJ025Ms1yAr3IJD4W68CbEybtr/qOSPFurxS8O7rCYqgn51CIOvXiklOADV8ZKwlXimOzv+CSh0CmNJ46Gz08IJvQ/OASbCZdpkdPlDr4+BXzv93hVrB/B+AUj3SAvUkvhMDWvQG9NU4oVfu4b+ltVoUhOyUV+HlqFZ+vFmulOQxHnBxTuyBy0YwayVFykV8NyGyS6mv90km/T5ZJcCCf2vWcJLRqhI9rBTqONBcvhBdvlV6RslsX0GHLWzrbdnaD93lVFS5stVkvWr/vM4m4Y5tfFaSatwGWMY6L/x+2E9+G8AWpWvKLTxMhJkeri9JyDpM0zqcuWmqRdFpzBlwH0iVRMXoqXQlosZzW0jFms80= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Sep 28, 2023 at 01:06:03PM -0400, Jeff Layton wrote: > On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > > This shaves 8 bytes off struct inode, according to pahole. > > > > > > Signed-off-by: Jeff Layton > > > > FWIW, this is similar to the approach that Deepa suggested > > back in 2016: > > > > https://lore.kernel.org/lkml/1452144972-15802-3-git-send-email-deepa.kernel@gmail.com/ > > > > It was NaKed at the time because of the added complexity, > > though it would have been much easier to do it then, > > as we had to touch all the timespec references anyway. > > > > The approach still seems ok to me, but I'm not sure it's worth > > doing it now if we didn't do it then. > > > > I remember seeing those patches go by. I don't remember that change > being NaK'ed, but I wasn't paying close attention at the time > > Looking at it objectively now, I think it's worth it to recover 8 bytes > per inode and open a 4 byte hole that Amir can use to grow the > i_fsnotify_mask. We might even able to shave off another 12 bytes > eventually if we can move to a single 64-bit word per timestamp. I don't think you can, since btrfs timestamps utilize s64 seconds counting in both directions from the Unix epoch. They also support ns resolution: struct btrfs_timespec { __le64 sec; __le32 nsec; } __attribute__ ((__packed__)); --D > It is a lot of churn though. > -- > Jeff Layton