Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755256Ab1BOPqi (ORCPT ); Tue, 15 Feb 2011 10:46:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50746 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751198Ab1BOPqh (ORCPT ); Tue, 15 Feb 2011 10:46:37 -0500 Date: Tue, 15 Feb 2011 15:46:25 +0000 From: Alasdair G Kergon To: Tejun Heo Cc: device-mapper development , Milan Broz , Jens Axboe , Tao Ma , linux-kernel@vger.kernel.org Subject: Re: [dm-devel] [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings Message-ID: <20110215154625.GG5825@agk-dp.fab.redhat.com> Mail-Followup-To: Tejun Heo , device-mapper development , Milan Broz , Jens Axboe , Tao Ma , linux-kernel@vger.kernel.org References: <4D5A6EF4.3030905@redhat.com> <20110215124629.GF5825@agk-dp.fab.redhat.com> <20110215152033.GK3160@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110215152033.GK3160@htj.dyndns.org> Organization: Red Hat UK Ltd. Registered in England and Wales, number 03798903. Registered Office: Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 952 Lines: 24 On Tue, Feb 15, 2011 at 04:20:33PM +0100, Tejun Heo wrote: > Hmmm... but -EACCES is the correct one here. The device node itself > is rejecting RW access. There's no FS which is enforcing RO. Exactly:) If the filesystem permissions were what was blocking this (say r--) then I'd agree with EACCES. Interpret those man pages in the context of 'pathname refers to a block device not a file'. If it's EACCES, I just need to gain more privilege/capabilities and then repeat the system call and it could succeed. But EROFS tells me however much extra privilege I get it's going to make no difference. That's why I'm arguing EACCES is not a good error to return and EROFS is more appropriate. Alasdair -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/