Date: Tue, 5 Apr 2005 23:55:27 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: current@freebsd.org Subject: Re: Panic on mount with write-locked USB media (umass) Message-ID: <20050405235414.D81173@fledge.watson.org> In-Reply-To: <2871.1112734748@critter.freebsd.dk> References: <2871.1112734748@critter.freebsd.dk>
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On Tue, 5 Apr 2005, Poul-Henning Kamp wrote:
> In message <20050405201820.042685D07@ptavv.es.net>, "Kevin Oberman" writes:
>
>>> It would be useful if mount was smart enough to notice when it is
>>> dealing with a read-only device, and try to mount such things
>>> read-only, rather than trying to mount things read-write by default and
>>> failing. Of course, the system shouldn't panic, either. :-)
>>
>> I think that is what I said. I am almost sure that this is how it used
>> to work. I'm not sure whether the change was caused by something in
>> msdosfs or GEOM (or somewhere else), but I sure preferred it when the RO
>> device mounted RO. CDs still do this (thankfully). This makes me suspect
>> msdosfs is the culprit.
>
> There are two ways that a filesystem correctly could handle a R/O media:
>
> 1. Fail with EROFS unless asked t mouned read-only
>
> 2. Silently downgrade th emount to read-only.
>
> I personally prefer the first because that way a script does not have to
> check if it got the mount it wanted or not.
In general, I agree, but this will de-POLA the following command:
mount -t cd9660 /dev/acd0 /cdrom
I wonder if a useful middle ground is to adopt (1) above except in the
case of perenially read-only file systems (cd9660), in which case (2) is
adopted?
Robert N M Watson
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