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Date: Wed, 12 Feb 2003 14:07:27 -0800
From: Chris Wedgwood <cw@f00f.org>
To: Bruno Diniz de Paula <diniz@cs.rutgers.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: O_DIRECT foolish question
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On Wed, Feb 12, 2003 at 04:19:24PM -0500, Bruno Diniz de Paula wrote:

> I am trying to use O_DIRECT to read ordinary files and read syscall
> always returns 0, unless when the file size equals the fs block
> size.

Sounds correct.

> Is it true that I can only use O_DIRECT when the size of the file
> written in the inode is a multiple of block size?

You usually can only do O_DIRECT reads/writes in multiples of the
block size (or in some cases multiples of 512-bytes, but I'm not sure
of that code is still about though).

It depends on the filesystem to some extent.


  --cw
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