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Date: Tue, 19 Feb 2002 14:20:00 -0700
From: Andreas Dilger <adilger@turbolabs.com>
To: Andrew Morton <akpm@zip.com.au>
Cc: Pavel Machek <pavel@ucw.cz>, kernel list <linux-kernel@vger.kernel.org>
Subject: Re: ENOTTY from ext3 code?
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In-Reply-To: <3C72BC0C.821EAB90@zip.com.au>; from akpm@zip.com.au on Tue, Feb 19, 2002 at 12:56:44PM -0800
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On Feb 19, 2002  12:56 -0800, Andrew Morton wrote:
> Pavel Machek wrote:
> > ext3/ioctl.c:
> > 
> > ...
> >         return -ENOTTY;
> > 
> > Does it really make sense to return "not a typewriter" from ext3
> > ioctl?
> 
> ERRORS
>        ...
> 
>        ENOTTY The specified request does not apply to the kind of
>               object that the descriptor d references.
> 
> Lots and lots of ioctls return ENOTTY when passed a request
> which they don't understand.  There's probably a great reason
> for this, but I can't immediately think what it might be.

Well, returning ENOTTY for unknown ioctls instead of EINVAL allows you
to distinguish between 'I have no idea what you are asking of me' and
'you passed me the incorrect parameter to this request' in the caller.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

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