From owner-freebsd-hackers@freebsd.org Thu Mar 9 21:48:17 2017 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 6038AD05BFE for ; Thu, 9 Mar 2017 21:48:17 +0000 (UTC) (envelope-from darius@dons.net.au) Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by mx1.freebsd.org (Postfix) with ESMTP id E8DE6D60 for ; Thu, 9 Mar 2017 21:48:15 +0000 (UTC) (envelope-from darius@dons.net.au) Received: from ppp118-210-168-9.bras2.adl6.internode.on.net (HELO midget.dons.net.au) ([118.210.168.9]) by ipmail05.adl6.internode.on.net with ESMTP; 10 Mar 2017 08:13:08 +1030 Received: from midget.dons.net.au (localhost [127.0.0.1]) by midget.dons.net.au (8.15.1/8.14.9) with ESMTPS id v29Lgon4062997 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Fri, 10 Mar 2017 08:13:02 +1030 (CST) (envelope-from darius@dons.net.au) Received: (from mailnull@localhost) by midget.dons.net.au (8.15.1/8.14.9/Submit) id v29LU6R7054445 for ; Fri, 10 Mar 2017 08:00:06 +1030 (CST) (envelope-from darius@dons.net.au) X-Authentication-Warning: midget.dons.net.au: mailnull set sender to using -f Received: from [10.0.2.26] ([10.0.2.26]) by ns.dons.net.au (envelope-sender ) (MIMEDefang) with ESMTP id v29LU3fT054082; Fri, 10 Mar 2017 08:00:06 +1030 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: open(): O_EVTONLY and O_NOATIME From: "O'Connor, Daniel" In-Reply-To: <20170309131136.GY30979@kib.kiev.ua> Date: Fri, 10 Mar 2017 08:00:03 +1030 Cc: Rozhuk Ivan , freebsd-hackers@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20170309022554.18875d07@rimwks> <20170308235016.GT30979@kib.kiev.ua> <20170309031532.0079ab35@rimwks> <20170309131136.GY30979@kib.kiev.ua> To: Konstantin Belousov X-Mailer: Apple Mail (2.3259) X-Spam-Score: -1 () No, score=-1.0 required=5.0 tests=ALL_TRUSTED autolearn=unavailable autolearn_force=no version=3.4.0 X-Scanned-By: MIMEDefang 2.75 on 10.0.2.1 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Mar 2017 21:48:17 -0000 > On 9 Mar 2017, at 23:41, Konstantin Belousov = wrote: >> This means that there is no way it could look at all the FDs which = have this file open and see they are all noatime and then disable atime = just for that one. >=20 > Well, I never claimed that the 'look at all the FDs' is needed. I = stated > that some plumbing to pass O_NOATIME flag from file down to VOPs is = needed > if this feature is implemented. Sorry, I didn't mean to put words in your mouth. I was just trying to = explain the concept as it seemed OP was having difficulty understanding = and you and he seemed to be talking past each other. >> You are right in that if an FS can be mounted noatime it should be = able to work but unfortunately there is no plumbing between the open of = the file and the file system that supports that. >=20 > I fail to understand this statement. How somebody's ability to edit = /etc/fstab > is related to potential unintended or malicious lack of metadata = update due > to the mis-use of the flags ? That wasn't what I was trying to say. OP said.. > If file system cant be mount with NOATIME - then it already ready to = support O_NOATIME. I took that to mean they thought that if an FS could be mounted noatime = then it should be able to support O_NOATIME. -- Daniel O'Connor "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C