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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D30E8ECDFAA for ; Thu, 12 Jul 2018 22:54:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86A3E208E3 for ; Thu, 12 Jul 2018 22:54:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 86A3E208E3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387538AbeGLXG0 (ORCPT ); Thu, 12 Jul 2018 19:06:26 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44390 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387438AbeGLXG0 (ORCPT ); Thu, 12 Jul 2018 19:06:26 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 878C54074475; Thu, 12 Jul 2018 22:54:43 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-149.rdu2.redhat.com [10.10.120.149]) by smtp.corp.redhat.com (Postfix) with ESMTP id 49FA0111AF3C; Thu, 12 Jul 2018 22:54:42 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20180712223223.GA28610@thunk.org> References: <20180712223223.GA28610@thunk.org> <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk> <153126264966.14533.3388004240803696769.stgit@warthog.procyon.org.uk> <686E805C-81F3-43D0-A096-50C644C57EE3@amacapital.net> <22370.1531293761@warthog.procyon.org.uk> <7002.1531407244@warthog.procyon.org.uk> <16699.1531426991@warthog.procyon.org.uk> <18233.1531430797@warthog.procyon.org.uk> To: "Theodore Y. Ts'o" Cc: dhowells@redhat.com, Linus Torvalds , Andrew Lutomirski , Al Viro , Linux API , linux-fsdevel , Linux Kernel Mailing List , Jann Horn Subject: Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <22104.1531436081.1@warthog.procyon.org.uk> Date: Thu, 12 Jul 2018 23:54:41 +0100 Message-ID: <22105.1531436081@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 12 Jul 2018 22:54:43 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 12 Jul 2018 22:54:43 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dhowells@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Theodore Y. Ts'o wrote: > So maybe the answer is that you open /dev/sda1 and /dev/sda2 and then > pass the file descriptors to the fsopen object? We can require that > the fd's be opened with O_RDWR and O_EXCL, which has the benefit where > if you have multiple block devices, you know *which* block device had > a problem with being grabbed for an exclusive open. Would that mean then that doing: mount /dev/sda3 /a mount /dev/sda3 /b would then fail on the second command because /dev/sda3 is already open exclusively? David