From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967579AbaFTNNi (ORCPT ); Fri, 20 Jun 2014 09:13:38 -0400 Received: from smtp2.macqel.be ([109.135.2.61]:54220 "EHLO smtp2.macqel.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965175AbaFTNNh (ORCPT ); Fri, 20 Jun 2014 09:13:37 -0400 Date: Fri, 20 Jun 2014 15:13:28 +0200 From: Philippe De Muyter To: Dave Chinner Cc: Andrew Morton , linux-kernel@vger.kernel.org, Al Viro Subject: Re: [PATCH] init/do_mounts.c: treat EROFS like EACCES Message-ID: <20140620131328.GA31693@frolo.macqel> References: <1403107964-1082-1-git-send-email-phdm@macqel.be> <20140619141950.18b9026d7d06694291eea311@linux-foundation.org> <20140619230924.GO4453@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140619230924.GO4453@dastard> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 20, 2014 at 09:09:24AM +1000, Dave Chinner wrote: > On Thu, Jun 19, 2014 at 02:19:50PM -0700, Andrew Morton wrote: > > On Wed, 18 Jun 2014 18:12:44 +0200 Philippe De Muyter wrote: > > > > > some combinations of filesystem and block device (at least vfat on mmc) > > > yield -EROFS instead of -EACCES when the device is read-only. Retry > > > mounting with MS_RDONLY set, just like for the EACCES case, instead of > > > failing directly. > > > > > > ... > > > > > > --- a/init/do_mounts.c > > > +++ b/init/do_mounts.c > > > @@ -394,6 +394,7 @@ retry: > > > case 0: > > > goto out; > > > case -EACCES: > > > + case -EROFS: > > > flags |= MS_RDONLY; > > > goto retry; > > > case -EINVAL: > > > > hm, what's going on here. I'd have thought it to be very logical that > > file_system_type.mount() would return EROFS if the device is read-only! > > But I'm suspecting that there is some convention that the fs is > > supposed to return EACCES in this case. So *perhaps* it is vfat-on-mmc > > which needs fixing. Dunno. > > > > Al, are you able to shed light? > > from the mount(2) man page: > > EACCES A component of a path was not searchable. (See also > path_resolution(7).) Or, mounting a read-only filesystem > was attempted without giving the MS_RDONLY flag. Or, the > block device source is located on a filesystem mounted with > the MS_NODEV option. > > So, when the device is read-only, the error should EACCES, not > EROFS. Would seem to me that vfat-on-mmc needs fixing... Looking at the sources of mount(1) https://github.com/karelzak/util-linux/blob/master/sys-utils/mount.c at line 601, we clearly see that mount(1) allows mount(2) to fail with EROFS. We could as well fix the man page of mount(2) Philippe -- Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles