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Date: Mon, 14 Jun 2010 10:12:56 -0400
From: tytso@mit.edu
To: Christoph Hellwig <hch@infradead.org>
Cc: Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
       Al Viro <viro@ZenIV.linux.org.uk>,
       "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [PATCH] Only honor the FIGETBSZ ioctl for regular files,
 directories, and symlinks
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	Al Viro <viro@ZenIV.linux.org.uk>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
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On Mon, Jun 14, 2010 at 10:07:30AM -0400, Christoph Hellwig wrote:
> On Mon, Jun 14, 2010 at 10:05:10AM -0400, Theodore Ts'o wrote:
> > FIGETBSZ has an ioctl number of _IO(0x00,2) == 2, which can conflict
> > with device driver ioctls.  Let's avoid the potential for problems by
> > only honoring the ioctl number for files where this ioctl is likely
> > going to be useful: regular files, directories, and symlinks.
> > 
> > Thanks to Johannes Stezenbach for pointing this consequence of commit
> > 19ba0559.
> 
> ioctl operate on a file descriptor, so you never call them on
> symbolic links.

Oops, good point.

> A comment explaining why we fall through here for special files is
> almost required.  Without that the chance of breaking it during the
> next random cleanup are far too high.

Sigh.  I had fixed that, but I failed to save emacs buffer before
creating commit.  Will resend with both fixes.

						- Ted
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