From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Becker Subject: Re: O_DIRECT and barriers Date: Fri, 21 Aug 2009 15:45:18 -0700 Message-ID: <20090821224518.GG4330@mail.oracle.com> References: <1250697884-22288-1-git-send-email-jack@suse.cz> <20090820221221.GA14440@infradead.org> <20090821114010.GG12579@kernel.dk> <20090821135403.GA6208@shareable.org> <20090821142635.GB30617@infradead.org> <20090821220852.GM9529@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Theodore Tso , Christoph Hellwig , Jamie Lokier , Jens Axboe , linux-fsdevel@vger.kernel.org, linux-scsi Return-path: Received: from acsinet12.oracle.com ([141.146.126.234]:21743 "EHLO acsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932267AbZHUWpz (ORCPT ); Fri, 21 Aug 2009 18:45:55 -0400 Content-Disposition: inline In-Reply-To: <20090821220852.GM9529@mit.edu> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, Aug 21, 2009 at 06:08:52PM -0400, Theodore Tso wrote: > http://ext4.wiki.kernel.org/index.php/Clarifying_Direct_IO's_Semantics > > Comments are welcome, either on the wiki's talk page, or directly to > me, or to the linux-fsdevel or linux-ext4. In the section on perhaps not waiting for buffered fallback, we need to clarify that O_DIRECT reads need to know to look in the pagecache. That is, if we decide that extending O_DIRECT writes without fsync can return before the data hits the storage, the caller shouldn't also have to call fsync() just to call read() of data they just wrote! Joel -- To spot the expert, pick the one who predicts the job will take the longest and cost the most. Joel Becker Principal Software Developer Oracle E-mail: joel.becker@oracle.com Phone: (650) 506-8127