From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mo4-p03-ob.smtp.rzone.de (mo4-p03-ob.smtp.rzone.de [81.169.146.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2AF631A68; Wed, 20 Sep 2023 13:01:05 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; t=1695214142; cv=none; d=strato.com; s=strato-dkim-0002; b=KK4wxmcg11bDhbWnUFC83uZ811y/mpb0I1TmJbK4Xk4jnQh4eSC/Y+vtwGlPKLxw9f ZQJV08gwelI0hs7Nko3i2MdGYFFoM9tT1tP4c6kr2+FD/bMZ5Us4S1IamSJP7z2u2Tni VGrvJR9cFI9cNWYNVXlV4wEMgQPoFUsGO26ode4TY1Iyrfpxra0unC1MrVpv8ibEB9+j zFGTjBklu569rK9lelqLmPbUbCvydW08SWCBN0VIPOuJD6DxdrrJwE7b+oQvIZvbb2gB gvGEBEb/Y1uiuRnorDANT4ornmti5i01W1zbKwyhST0ousOicmaYHuksmnMxb6uUQJSc GcjQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; t=1695214142; s=strato-dkim-0002; d=strato.com; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Cc:Date: From:Subject:Sender; bh=zlon1NnZN5jZFLvNv3xx2YjDrrfzc/zzmMPbj7gP0jk=; b=d2z+l5GTzEzeupyyKoEO/+801nRO2I8xrBbgDMbJ0FszbQsZ7OWKerKKY869DbFMSr DA55dD3c8Iy22q32azarKo9LmVUAE/wwLMEkbofjeQtY2NHv5KyEQ5lCwDIcZj6/Dssl rR06w99QqJPCaVp01TF7Yn083P4ftn6AoEorFHVtk+giqDT7I9UeWxfbrgljCBX0K9NB 27KHTBXszEyKAusPHW96Eg39CS+TryRIAsU+dqtvvDkSuODIRZZtwIQ1GsA7NETvfjHn VcnTxIDslnv+v3qX0yKYPfHAa3QFZGq2mRblvL54+mqYfwy9M1pc+w1udoTKxkxma9Q+ sJBw== ARC-Authentication-Results: i=1; strato.com; arc=none; dkim=none X-RZG-CLASS-ID: mo03 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1695214142; s=strato-dkim-0002; d=clisp.org; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Cc:Date: From:Subject:Sender; bh=zlon1NnZN5jZFLvNv3xx2YjDrrfzc/zzmMPbj7gP0jk=; b=O12Jm8BsjyLsoq3xcyYi16mtuh91ZCa5znbPcUnLqZstPIUAkcvAVtfQJ5y2yLTnkG Bbd1Vjx8o91hiawH0LIwFIUvSMwyAjpO+JZjkt3g+Qpq83IYi33H61+PZsHsDjUPV+gY 5VkfMVdagu9bFaEq9tpHPC8aYSffOTVdZHc9t/Mr9BI62tRv6l/vCIVCxLdoBqlXpQ01 P1/x918UXZr3OP5PUsCgWe+NPzvAlgR7TOhOMxOk5E0RnLfQmpNp6vkh2VWa4G4mfKF1 8rEFhafAogS/DwPxgDZRaiLuEskuztanzAxVYeOjpAoKDywwLsnNuTQKZWxS/0d3sF8x RUJQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; t=1695214142; s=strato-dkim-0003; d=clisp.org; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Cc:Date: From:Subject:Sender; bh=zlon1NnZN5jZFLvNv3xx2YjDrrfzc/zzmMPbj7gP0jk=; b=muQUVTl0scIb2+N29B0TOhmsUwAw8Fpx6zlqzw9owQDn3QGFXl2h7ouqcgMeKa+h7z NeiR9RifaRHNd7IhFiCQ== X-RZG-AUTH: ":Ln4Re0+Ic/6oZXR1YgKryK8brlshOcZlIWs+iCP5vnk6shH0WWb0LN8XZoH94zq68+3cfpPHj6eWWaUQFt689wZebbvySt9BLA==" Received: from nimes.localnet by smtp.strato.de (RZmta 49.8.2 AUTH) with ESMTPSA id m03934z8KCmwmFD (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Wed, 20 Sep 2023 14:48:58 +0200 (CEST) From: Bruno Haible To: Jan Kara , Christian Brauner , Jeff Layton Cc: Xi Ruoyao , bug-gnulib@gnu.org, Alexander Viro , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , Christian Schoenebeck , David Howells , Marc Dionne , Chris Mason , Josef Bacik , David Sterba , Xiubo Li , Ilya Dryomov , Jan Harkes , coda@cs.cmu.edu, Tyler Hicks , 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 , Bo b Peterson , Andreas Gruenbacher , Greg Kroah-Hartman , Tejun Heo , Trond Myklebust , Anna Schumaker , Konstantin Komarov , Mark Fasheh , Joel Becker , Joseph Qi , Mike Marshall , Martin Brandenburg , Luis Chamberlain , Kees Cook , Iurii Zaikin , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Tom Talpey , Sergey Senozhatsky , Richard Weinberger , Hans de Goede , Hugh Dickins , Andrew Morton , Amir Goldstein , "Darrick J. Wong" , Benjamin Coddington , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, v9fs@lists.linux.dev, linux-afs@lists.infradead.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, codalist@coda.cs.cmu.edu, ecryptfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, ntfs3@lists.linux.dev, ocfs2-devel@lists.linux.dev, devel@lists.orangefs.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-mtd@lists.infradead.org, linux-mm@kvack.org, linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH v7 12/13] ext4: switch to multigrain timestamps Date: Wed, 20 Sep 2023 14:48:57 +0200 Message-ID: <5317021.Rkz2Fa4CmG@nimes> In-Reply-To: <317d84b1b909b6c6519a2406fcb302ce22dafa41.camel@kernel.org> References: <20230807-mgctime-v7-0-d1dec143a704@kernel.org> <20230920101731.ym6pahcvkl57guto@quack3> <317d84b1b909b6c6519a2406fcb302ce22dafa41.camel@kernel.org> Precedence: bulk X-Mailing-List: ntfs3@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" Jeff Layton wrote: > > Surely this is a safe choice as it moves the responsibility to the sysa= dmin > > and the cases where finegrained timestamps are required. But I kind of > > wonder how is the sysadmin going to decide whether mgtime is safe for h= is > > system or not? Because the possible breakage needn't be obvious at the > > first sight... >=20 > That's the main reason I really didn't want to go with a mount option. > Documenting that may be difficult. You could document it like this: The mgtime option enables more precise modification times (mtime) on some files, together with an optimization that limits the amount of metadata changes. Note that this option may, in some cases, after writing to file F1 and then writing to file F2, report a lower mtime for F2 than for F2. Enabling this option may be useful on file systems shared via NFS. The safe choice is to disable this option. =46or me as a user, there's no need to go into more details than that. It's important to have this mount option, for people who want maximum reliability. Personally, I always enable the 'strictatime' option on all ext4 mounts, since 'relatime' optimizes too much for my use-cases. If I fear wrong results of "make" runs, I will definitely opt for the safe choice regarding mgtime as well =E2=80=94 since I don't want to spend hours debugging binaries that were built incorrectly from correct source code. Bruno