From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761962AbZJJQQM (ORCPT ); Sat, 10 Oct 2009 12:16:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761949AbZJJQQJ (ORCPT ); Sat, 10 Oct 2009 12:16:09 -0400 Received: from verein.lst.de ([213.95.11.210]:34982 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761948AbZJJQQI (ORCPT ); Sat, 10 Oct 2009 12:16:08 -0400 Date: Sat, 10 Oct 2009 18:15:31 +0200 From: Christoph Hellwig To: linux-kernel@vger.kernel.org Subject: Re: [PATCH] blkdev: flush disk cache on ->fsync Message-ID: <20091010161531.GA30289@lst.de> References: <20090820182432.GA31520@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090820182432.GA31520@lst.de> User-Agent: Mutt/1.3.28i X-Spam-Score: 0 () Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Is anyone going to pick up this patch? On Thu, Aug 20, 2009 at 08:24:32PM +0200, Christoph Hellwig wrote: > Currently there is no barrier support in the block device code. That > means we cannot guarantee any sort of data integerity when using the > block device node with dis kwrite caches enabled. Using the raw block > device node is a typical use case for virtualization (and I assume > databases, too). This patch changes block_fsync to issue a cache flush > and thus make fsync on block device nodes actually useful. > > Note that in mainline we would also need to add such code to the > ->aio_write method for O_SYNC handling, but assuming that Jan's patch > series for the O_SYNC rewrite goes in it will also call into ->fsync > for 2.6.32. > > > Signed-off-by: Christoph Hellwig > > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 94dfda2..298ad75 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -398,7 +398,17 @@ static loff_t block_llseek(struct file *file, loff_t offset, int origin) > > static int block_fsync(struct file *filp, struct dentry *dentry, int datasync) > { > - return sync_blockdev(I_BDEV(filp->f_mapping->host)); > + struct block_device *bdev = I_BDEV(filp->f_mapping->host); > + int error; > + > + error = sync_blockdev(bdev); > + if (error) > + return error; > + > + error = blkdev_issue_flush(bdev, NULL); > + if (error == -EOPNOTSUPP) > + error = 0; > + return error; > } > > /* ---end quoted text---