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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8F429EB64D8 for ; Wed, 21 Jun 2023 23:23:12 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=PiPk49g+; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Qmfgf5qRKz3bjc for ; Thu, 22 Jun 2023 09:23:10 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=PiPk49g+; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4641:c500::1; helo=dfw.source.kernel.org; envelope-from=jlayton@kernel.org; receiver=lists.ozlabs.org) Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4QmXZx1Q6tz3dDx; Thu, 22 Jun 2023 04:48:41 +1000 (AEST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 75C6F616AB; Wed, 21 Jun 2023 18:48:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB234C433C8; Wed, 21 Jun 2023 18:48:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1687373315; bh=a5OpkE0TU4uPAvSOWcyUKhr2U/OaDDTahqvZpyNm/D4=; h=Subject:From:To:Date:In-Reply-To:References:From; b=PiPk49g+MFOu/O2ZwDxO/8QAjKIZGlhjql5KOg56o+z0jsrDavO9BiaXOtkYto876 fJ7qYzZ7aATc9kPncdP1kCdlY5wqINNGdYK2LGj2HmV63uWD5NHZ4+OFVQ4t30vFE9 rYDpgx917Jc/lUMtGxdnWxKlhyndYbn3MftPxoStquXW6wJVzxk1ZBM8Z7BTbv2h/U qJjwHaLWN8lUJ3h6C5OcO+D166wrcNaWoWGX2W/vO7mNHZJIsw6euWqEIeYa7S4lF3 jaX3jg20U9mjcF803nObNGAx9i1QbKIM3FZeyHr6EhjkD9DNtiQVqDSkHfY1GNj8rV 9eRPHwtyQHGGQ== Message-ID: Subject: Re: [PATCH 01/79] fs: add ctime accessors infrastructure From: Jeff Layton To: Tom Talpey , Jeremy Kerr , Arnd Bergmann , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Greg Kroah-Hartman , Arve =?ISO-8859-1?Q?Hj=F8nnev=E5g?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Carlos Llamas , Suren Baghdasaryan , Dennis Dalessandro , Jason Gunthorpe , Leon Romanovsky , Brad Warrum , Ritu Agarwal , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , Christian Schoenebeck , David Sterba , David Howells , Marc Dionne , Alexander Viro , Ian Kent , Luis de Bethencourt , Salah Triki , "Tigran A. Aivazian" , Eric Biederman , Kees Cook , Chris Mason , Josef Bacik , Xiubo Li , Ilya Dryomov , Jan Harkes , coda@cs.cmu.edu, Joel Becker , Christoph Hellwig , Nicolas Pitre , "Rafael J. Wysocki" , Tyler Hicks , Ard Biesheuvel , Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Namjae Jeon , Sungjong Seo , Jan Kara , Theodore Ts'o , Andreas Dilger , Jaegeuk Kim , OGAWA Hirofumi , Miklos Szeredi , Bob Peterson , Andreas Gruenbacher , Richard Weinberger , Anton Ivanov , Johannes Berg , Mikulas Patocka , Mike Kravetz , Muchun Song , David Woodhouse , Dave Kleikamp , Tejun Heo , Trond Myklebust , Anna Schumaker , Chuck Lever , 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 , Hans de Goede , "Darrick J. Wong" , 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 , Juergen Gross , Ruihan Li , Laurent Pinchart , Wolfram Sang , Udipto Goswami , Linyu Yuan , John Keeping , Andrzej Pietrasiewicz , Dan Carpenter , Yuta Hayama , Jozef Martiniak , Jens Axboe , Alan Stern , Sandeep Dhavale , Dave Chinner , Johannes Weiner , ZhangPeng , Viacheslav Dubeyko , Tetsuo Handa , Aditya Garg , Erez Zadok , Yifei Liu , Yu Zhe , "Matthew Wilcox (Oracle)" , Oleg Kanatov , "Dr. David Alan Gilbert" , Jiangshan Yi , xu xin , Stefan Roesch , Zhihao Cheng , "Liam R. Howlett" , Alexey Dobriyan , Minghao Chi , Seth Forshee , Zeng Jingxiang , Bart Van Assche , Mimi Zohar , Roberto Sassu , Zhang Yi , Tom Rix , "Fabio M. De Francesco" , Chen Zhongjin , Zhengchao Shao , Rik van Riel , Jingyu Wang , Hangyu Hua , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, linux-usb@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, autofs@vger.kernel.org, linux-mm@kvack.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, codalist@coda.cs.cmu.edu, ecryptfs@vger.kernel.org, linux-efi@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, 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@oss.oracle.com, 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@vger.kernel.org, apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Date: Wed, 21 Jun 2023 14:48:17 -0400 In-Reply-To: References: <20230621144507.55591-1-jlayton@kernel.org> <20230621144507.55591-2-jlayton@kernel.org> <1f97d595-e035-46ce-6269-eebfe922cf35@talpey.com> <6f4bcd7d79f688120d80e96e86d7c521854d8e84.camel@kernel.org> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.3 (3.48.3-1.fc38) MIME-Version: 1.0 X-Mailman-Approved-At: Thu, 22 Jun 2023 09:22:21 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, 2023-06-21 at 14:19 -0400, Tom Talpey wrote: > On 6/21/2023 2:01 PM, Jeff Layton wrote: > > On Wed, 2023-06-21 at 13:29 -0400, Tom Talpey wrote: > > > On 6/21/2023 10:45 AM, Jeff Layton wrote: > > > > struct timespec64 has unused bits in the tv_nsec field that can be = used > > > > for other purposes. In future patches, we're going to change how th= e > > > > inode->i_ctime is accessed in certain inodes in order to make use o= f > > > > them. In order to do that safely though, we'll need to eradicate ra= w > > > > accesses of the inode->i_ctime field from the kernel. > > > >=20 > > > > Add new accessor functions for the ctime that we can use to replace= them. > > > >=20 > > > > Signed-off-by: Jeff Layton > > > > --- > > > > fs/inode.c | 16 ++++++++++++++ > > > > include/linux/fs.h | 53 ++++++++++++++++++++++++++++++++++++++++= +++++- > > > > 2 files changed, 68 insertions(+), 1 deletion(-) > > > >=20 > > > > diff --git a/fs/inode.c b/fs/inode.c > > > > index d37fad91c8da..c005e7328fbb 100644 > > > > --- a/fs/inode.c > > > > +++ b/fs/inode.c > > > > @@ -2499,6 +2499,22 @@ struct timespec64 current_time(struct inode = *inode) > > > > } > > > > EXPORT_SYMBOL(current_time); > > > > =20 > > > > +/** > > > > + * inode_ctime_set_current - set the ctime to current_time > > > > + * @inode: inode > > > > + * > > > > + * Set the inode->i_ctime to the current value for the inode. Retu= rns > > > > + * the current value that was assigned to i_ctime. > > > > + */ > > > > +struct timespec64 inode_ctime_set_current(struct inode *inode) > > > > +{ > > > > + struct timespec64 now =3D current_time(inode); > > > > + > > > > + inode_set_ctime(inode, now); > > > > + return now; > > > > +} > > > > +EXPORT_SYMBOL(inode_ctime_set_current); > > > > + > > > > /** > > > > * in_group_or_capable - check whether caller is CAP_FSETID priv= ileged > > > > * @idmap: idmap of the mount @inode was found from > > > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > > > index 6867512907d6..9afb30606373 100644 > > > > --- a/include/linux/fs.h > > > > +++ b/include/linux/fs.h > > > > @@ -1474,7 +1474,58 @@ static inline bool fsuidgid_has_mapping(stru= ct super_block *sb, > > > > kgid_has_mapping(fs_userns, kgid); > > > > } > > > > =20 > > > > -extern struct timespec64 current_time(struct inode *inode); > > > > +struct timespec64 current_time(struct inode *inode); > > > > +struct timespec64 inode_ctime_set_current(struct inode *inode); > > > > + > > > > +/** > > > > + * inode_ctime_peek - fetch the current ctime from the inode > > > > + * @inode: inode from which to fetch ctime > > > > + * > > > > + * Grab the current ctime from the inode and return it. > > > > + */ > > > > +static inline struct timespec64 inode_ctime_peek(const struct inod= e *inode) > > > > +{ > > > > + return inode->i_ctime; > > > > +} > > > > + > > > > +/** > > > > + * inode_ctime_set - set the ctime in the inode to the given value > > > > + * @inode: inode in which to set the ctime > > > > + * @ts: timespec value to set the ctime > > > > + * > > > > + * Set the ctime in @inode to @ts. > > > > + */ > > > > +static inline struct timespec64 inode_ctime_set(struct inode *inod= e, struct timespec64 ts) > > > > +{ > > > > + inode->i_ctime =3D ts; > > > > + return ts; > > > > +} > > > > + > > > > +/** > > > > + * inode_ctime_set_sec - set only the tv_sec field in the inode ct= ime > > >=20 > > > I'm curious about why you choose to split the tv_sec and tv_nsec > > > set_ functions. Do any callers not set them both? Wouldn't a > > > single call enable a more atomic behavior someday? > > >=20 > > > inode_ctime_set_sec_nsec(struct inode *, time64_t, time64_t) > > >=20 > > > (or simply initialize a timespec64 and use inode_ctime_spec() ) > > >=20 > >=20 > > Yes, quite a few places set the fields individually. For example, when > > loading a value from disk that doesn't have sufficient granularity to > > set the nsecs field to anything but 0. >=20 > Well, they still need to set the tv_nsec so they could just pass 0. > But ok. >=20 Sure. The difficulty is in trying to do this in an automated way. For instance, look at the hfsplus patch; it has separate assignments in place already: - result->i_ctime.tv_sec =3D result->i_mtime.tv_sec =3D result->i_ati= me.tv_sec =3D local_to_gmt(dir->i_sb, le32_to_cpu(dee.creation_date)); - result->i_ctime.tv_nsec =3D 0; + inode_ctime_set_sec(result, + result->i_mtime.tv_sec =3D result->i_atime.tv_s= ec =3D local_to_gmt(dir->i_sb, le32_to_cpu(dee.creation_date))); + inode_ctime_set_nsec(result, 0); Granted the new code is pretty ugly, but it compiles! Transforming that into what you're suggesting is a tougher proposition to do with coccinelle. I didn't see a way to conditionally catch cases like this, declare a new variable in the appropriate spot and then transform two assignments (that may not be next to one another!) into a single one. Maybe it's possible, but my grasp of SMPL is not that great. The docs and examples (including Kees' vey helpful ones!) cover fairly simple changes well, but I didn't quite grasp how to do that complex an evolution. > > Could I have done it by declaring a local timespec64 variable and just > > use the inode_ctime_set function in these places? Absolutely. > >=20 > > That's a bit more difficult to handle with coccinelle though. If someon= e > > wants to suggest a way to do that without having to change all of these > > call sites manually, then I'm open to redoing the set. > >=20 > > That might be better left for a later cleanup though. >=20 > Acked-by: Tom Talpey >=20 Many thanks! > > > > + * @inode: inode in which to set the ctime > > > > + * @sec: value to set the tv_sec field > > > > + * > > > > + * Set the sec field in the ctime. Returns @sec. > > > > + */ > > > > +static inline time64_t inode_ctime_set_sec(struct inode *inode, ti= me64_t sec) > > > > +{ > > > > + inode->i_ctime.tv_sec =3D sec; > > > > + return sec; > > > > +} > > > > + > > > > +/** > > > > + * inode_ctime_set_nsec - set only the tv_nsec field in the inode = ctime > > > > + * @inode: inode in which to set the ctime > > > > + * @nsec: value to set the tv_nsec field > > > > + * > > > > + * Set the nsec field in the ctime. Returns @nsec. > > > > + */ > > > > +static inline long inode_ctime_set_nsec(struct inode *inode, long = nsec) > > > > +{ > > > > + inode->i_ctime.tv_nsec =3D nsec; > > > > + return nsec; > > > > +} > > > > =20 > > > > /* > > > > * Snapshotting support. > >=20 --=20 Jeff Layton