From owner-freebsd-fs  Sun Nov 24 23: 3:12 2002
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Date: Mon, 25 Nov 2002 18:16:25 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Julian Elischer <julian@elischer.org>
Cc: fs@FreeBSD.ORG, <mckusick@mckusick.com>
Subject: Re: ufs types
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On Fri, 22 Nov 2002, Julian Elischer wrote:

> We had a system on site today that fell over every time re tried to boot
> it. Causing delays in probably many millions of dollars of transfers.
> The reason was a currupt word in the cylinder group summary information.
> a word had been trashed becoming -ve, and fsck didn't check against
> -ve numbers in that (a rotor value). Noticing that most fields are not
> checked against being -ve in fsck we started looking at fixing it..
> until we realised that the far quicker answer was to define them to be
> unsigned in ufs.h and just fix the compile errors.. The values are
> usually checked for reasonable +ve values.
>
> Does anyone have a reason why we should not do this in FreeBSD?

Yes.  Unsigned types give a morass or (un)sign extension and (non)overflow
problems, especially when they are mixed with signed types.

Bruce


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