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 EA72FEB64D8 for ; Wed, 21 Jun 2023 18:50:58 +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=bVcrCvUx; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4QmXdY1yCMz3dRX for ; Thu, 22 Jun 2023 04:50:57 +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=bVcrCvUx; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=139.178.84.217; helo=dfw.source.kernel.org; envelope-from=jlayton@kernel.org; receiver=lists.ozlabs.org) Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) (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 4QmWXV4LqGz300q; Thu, 22 Jun 2023 04:01:30 +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 F2317614C7; Wed, 21 Jun 2023 18:01:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 994ABC433C8; Wed, 21 Jun 2023 18:01:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1687370487; bh=f6MfE+OwYlooIGk6bzrRy2nMoaF6fYVrxR9rt/b+wHA=; h=Subject:From:To:Date:In-Reply-To:References:From; b=bVcrCvUx5qUKiFKoGoCpRU9cOdPpOKYso9mJvg46pEjfpa5HrNdfQIs+z6jHr5sux dlx89O00OX+JFXaZsV1aqCsQCXMgGUPun8gG0+O63APDuieKF+NHNtURapcBRt6lwA XUSZY7Lxndjjm0Guu7ABZsDoRASFWxW9NDkbTecnzII3k7EzTCDZqTBAfGwPJVYC9o 4y1h+nwRvjsJy2OJKNcBHeZcxgyGTH5ATcgrCrgxjm4t9FpTdCYfY2dSxFdgqaYmjq McRt37g4zUkhYaqSUzhLnP9BOtEXfLTVHkZOUz8jt6fW2f8bh/uJnCW9nUVVVNS/3d grPvoD0B9Xewg== Message-ID: <6f4bcd7d79f688120d80e96e86d7c521854d8e84.camel@kernel.org> 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. 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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 14:01:09 -0400 In-Reply-To: <1f97d595-e035-46ce-6269-eebfe922cf35@talpey.com> References: <20230621144507.55591-1-jlayton@kernel.org> <20230621144507.55591-2-jlayton@kernel.org> <1f97d595-e035-46ce-6269-eebfe922cf35@talpey.com> 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 04:32:35 +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 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 the > > inode->i_ctime is accessed in certain inodes in order to make use of > > them. In order to do that safely though, we'll need to eradicate raw > > accesses of the inode->i_ctime field from the kernel. > >=20 > > Add new accessor functions for the ctime that we can use to replace the= m. > >=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 *ino= de) > > } > > 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. Returns > > + * 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 privilege= d > > * @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(struct s= uper_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 inode *i= node) > > +{ > > + 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 *inode, s= truct timespec64 ts) > > +{ > > + inode->i_ctime =3D ts; > > + return ts; > > +} > > + > > +/** > > + * inode_ctime_set_sec - set only the tv_sec field in the inode ctime >=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 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. Could I have done it by declaring a local timespec64 variable and just use the inode_ctime_set function in these places? Absolutely. That's a bit more difficult to handle with coccinelle though. If someone 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. That might be better left for a later cleanup though. > > + * @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, time64= _t sec) > > +{ > > + inode->i_ctime.tv_sec =3D sec; > > + return sec; > > +} > > + > > +/** > > + * inode_ctime_set_nsec - set only the tv_nsec field in the inode ctim= e > > + * @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 Jeff Layton