Date: Wed, 3 May 2006 16:35:18 +1000
From: Nathan Scott <nathans@sgi.com>
To: Linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: O_DIRECT, ext3fs, kernel 2.4.32... again
Message-ID: <20060503163518.A1929541@wobbly.melbourne.sgi.com>
References: <20060427063249.GH761@DervishD> <20060501062058.GA16589@dmt> <20060501112303.GA1951@DervishD> <20060502072808.A1873249@wobbly.melbourne.sgi.com> <20060502172411.GA6112@DervishD> <20060503060336.A1918058@wobbly.melbourne.sgi.com> <20060503052752.GA20657@DervishD>
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In-Reply-To: <20060503052752.GA20657@DervishD>; from lkml@dervishd.net on Wed, May 03, 2006 at 07:27:52AM +0200
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On Wed, May 03, 2006 at 07:27:52AM +0200, DervishD wrote:
> ...
>  Are the differences too large?

Yep.

>     I know that this change would be intrusive and probably large,
> but IMHO is a quite important bug, because it prevents apps to
> selectively disable O_DIRECT (the flag is accepted by open(), so
> there's no reason the app should bother about which caused the
> read()/write() failures. In fact, is very difficult to know that
> those failures are caused by partial/buggy support of O_DIRECT flag).

You could open for direct, do a direct read, and see if it fails.
If it fails, clear O_DIRECT on the fd via fcntl(F_SETFL) then do
regular buffered IO instead... a bit hacky, but should work fine
I think.

cheers.

-- 
Nathan
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