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Date:      Fri, 1 Apr 2011 11:35:50 -0400
From:      Andrew Duane <aduane@juniper.net>
To:        Andriy Gapon <avg@FreeBSD.org>
Cc:        FreeBSD Hackers <freebsd-hackers@FreeBSD.org>, FreeBSD Arch <freebsd-arch@FreeBSD.org>
Subject:   RE: looking for error codes
Message-ID:  <AC6674AB7BC78549BB231821ABF7A9AEB52F1950BD@EMBX01-WF.jnpr.net>
In-Reply-To: <4D95ECDE.1020504@FreeBSD.org>
References:  <4D95E162.40605@FreeBSD.org>, <F98114A0-0C00-46EF-BD0C-E48F97FFF3E1@bsdimp.com> <AC6674AB7BC78549BB231821ABF7A9AEB52F1950BB@EMBX01-WF.jnpr.net>, <4D95ECDE.1020504@FreeBSD.org>

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My work is absolutely NOT in any shape at all to even consider, it's a real=
ly tailored point solution to a specific platform issue. I've been working =
with another engineer to expand it and make it more generic, but that effor=
t is stalled at the moment.

My plan was to add something like an ioctl to a device that would query it =
for read/write status, and percolate that up through the geom layer to capt=
ure it for mount requests. The correct place to stop it is at mount time. E=
ven mounting a read-only device as read-write will eventually panic the sys=
tem as super-block flag updates will not be able to complete. Once that is =
done, any attempt to open a file for writing fails.

--
Andrew Duane             Juniper Networks
978-589-0551              10 Technology Park Dr
aduane@juniper.net      Westford, MA  01886-3418

________________________________________
From: Andriy Gapon [avg@FreeBSD.org]
Sent: Friday, April 01, 2011 11:18 AM
To: Andrew Duane
Cc: Warner Losh; FreeBSD Hackers; FreeBSD Arch
Subject: Re: looking for error codes

on 01/04/2011 18:04 Andrew Duane said the following:
> AFAIK, FreeBSD does not really detect read-only media. This was something=
 I had to add as a small project here at work, and was considering cleaning=
 up to try to get into CURRENT. If there's a real need for it, I could spee=
d that up.
>

Yes, that's exactly the problem that I am looking at.
So if you have anything to share it will be greatly appreciated at least by=
 me.
But I think many more people could benefit from it (e.g. those having SD/SD=
HC/etc
cards).
Thanks!

> ________________________________________
> From: owner-freebsd-hackers@freebsd.org [owner-freebsd-hackers@freebsd.or=
g] On Behalf Of Warner Losh [imp@bsdimp.com]
> Sent: Friday, April 01, 2011 10:51 AM
> To: Andriy Gapon
> Cc: FreeBSD Hackers; FreeBSD Arch
> Subject: Re: looking for error codes
>
> On Apr 1, 2011, at 8:29 AM, Andriy Gapon wrote:
>
>>
>> I am looking for error codes that would unambiguously signal that a disk=
 drive has
>> readonly or write-protected media and that disk drive has no media at th=
e moment.
>> I foresee these error codes being used mostly between disk peripheral dr=
ivers and
>> filesystem drivers.
>>
>> I will appreciate your suggestions.
>>
>> P.S.
>> I see that Linux uses EROFS and ENOMEDIUM for these purposes.
>> I am not sure about EROFS in this role.
>> And we don't have ENOMEDIUM (nor EMEDIUMTYPE).
>
> Maybe we could add ENOMEDIA for that (spelled however Linux spells it) af=
ter EDAVE.

--
Andriy Gapon



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