From owner-freebsd-fs@FreeBSD.ORG  Fri Apr  8 12:11:06 2011
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 250A61065674;
	Fri,  8 Apr 2011 12:11:06 +0000 (UTC) (envelope-from avg@FreeBSD.org)
Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140])
	by mx1.freebsd.org (Postfix) with ESMTP id 37B2B8FC15;
	Fri,  8 Apr 2011 12:11:04 +0000 (UTC)
Received: from odyssey.starpoint.kiev.ua (alpha-e.starpoint.kiev.ua
	[212.40.38.101])
	by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id PAA05618;
	Fri, 08 Apr 2011 15:11:01 +0300 (EEST)
	(envelope-from avg@FreeBSD.org)
Message-ID: <4D9EFB55.1000706@FreeBSD.org>
Date: Fri, 08 Apr 2011 15:11:01 +0300
From: Andriy Gapon <avg@FreeBSD.org>
User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US;
	rv:1.9.2.15) Gecko/20110309 Lightning/1.0b2 Thunderbird/3.1.9
MIME-Version: 1.0
To: Garrett Cooper <yanegomi@gmail.com>
References: <4D9DF375.4080506@FreeBSD.org>
	<BANLkTimAyh4-T0gQ1cuQn0nm8m7SHwW5iA@mail.gmail.com>
In-Reply-To: <BANLkTimAyh4-T0gQ1cuQn0nm8m7SHwW5iA@mail.gmail.com>
X-Enigmail-Version: 1.1.2
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Cc: freebsd-fs@FreeBSD.org, FreeBSD Hackers <freebsd-hackers@FreeBSD.org>
Subject: Re: retry mounting with ro when rw fails
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 08 Apr 2011 12:11:06 -0000

on 07/04/2011 23:20 Garrett Cooper said the following:
> 
>     As a generic question / observation, maybe we should just
> implement 'errors=remount-ro' (or a reasonable facsimile) like Linux
> has in our mount(8) command? Doesn't look like NetBSD, OpenBSD, or
> [Open]Solaris sported similar functionality.

No problem, I am OK with being first.
Then, I only want to deal with media that is "semi-permanently" or permanetly
read-only.  That's why I handle only failure to mount media as R/W.

But from what I read 'errors=remount-ro' in Linux has to do with errors that
happen after filesystem is mounted.  That is, you mounted a filesystem, you work
with it, you get some error (e.g. because of bad blocks), you auto-downgrade the
filesystem to readonly.  This may be a nice feature, but this is something
different from what I proposed.

And, AFAIK, Linux does what I propose by default, without any additional options.
Google for "block device ... is write-protected, mounting read-only".
But yes, it seems that they handle this situation entirely in userland.
And I am not against it.

-- 
Andriy Gapon