Subject: Re: another nfs puzzle
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Peter Staubach <staubach@redhat.com>
Cc: Kenny Simpson <theonetruekenny@yahoo.com>, linux-kernel@vger.kernel.org
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Date: Wed, 07 Dec 2005 10:41:57 -0500
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On Wed, 2005-12-07 at 10:34 -0500, Peter Staubach wrote:

> This seems like a dangerous enough area that denying mmap on a file which
> has been opened with O_DIRECT by any process and denying open(O_DIRECT)
> on a file which has been mmap'd would be a good thing.  These things are
> easy enough to keep track of, so it shouldn't be too hard to implement.

That would be a recipe for DOSes as it would allow one process to block
another just by opening a file. I'd really not like to see my database
crash just because some obscure monitoring program happens to use mmap()
to browse the file.

Cheers,
  Trond

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