From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: adding proper O_SYNC/O_DSYNC, was Re: O_DIRECT and barriers
Date: Fri, 28 Aug 2009 18:39:54 -0400
Message-ID: <20090828223953.GA11591@infradead.org>
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Cc: Christoph Hellwig <hch@infradead.org>,
	Ulrich Drepper <drepper@redhat.com>,
	Jamie Lokier <jamie@shareable.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	torvalds@linux-foundation.org
To: Trond Myklebust <trond.myklebust@fys.uio.no>
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On Fri, Aug 28, 2009 at 05:43:05PM -0400, Trond Myklebust wrote:
> If you are going to automatically set O_DSYNC in open(), then
> fcntl(F_SETFL) might get a bit nasty.
> 
> Imagine using it after the open in order to clear the O_ISYNC flag;
> you'll still be left with the O_DSYNC (which you never set in the first
> place). That would be confusing...

Indeed, that's a killer argument for the first variant.  We just need
to make it extremly clear (manpage _and_ comments) that only O_SYNC is
an exposed user interface and that O_WHATEVER_SYNC is an implementation
detail.