Re: O_DIRECT foolish question

From: Chris Wedgwood (
Date: Wed Feb 12 2003 - 17:07:27 EST

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.

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