Re: adding proper O_SYNC/O_DSYNC, was Re: O_DIRECT and barriers

From: Christoph Hellwig
Date: Fri Aug 28 2009 - 18:40:13 EST


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.
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