From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263221AbTLQCCv (ORCPT ); Tue, 16 Dec 2003 21:02:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263267AbTLQCCv (ORCPT ); Tue, 16 Dec 2003 21:02:51 -0500 Received: from fw.osdl.org ([65.172.181.6]:37264 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S263221AbTLQCCu (ORCPT ); Tue, 16 Dec 2003 21:02:50 -0500 Date: Tue, 16 Dec 2003 18:03:19 -0800 From: Andrew Morton To: Daniel McNeil Cc: janetmor@us.ibm.com, suparna@in.ibm.com, pbadari@us.ibm.com, linux-aio@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH linux-2.6.0-test10-mm1] filemap_fdatawait.patch Message-Id: <20031216180319.6d9670e4.akpm@osdl.org> In-Reply-To: <1071624314.1826.12.camel@ibm-c.pdx.osdl.net> References: <3FCD4B66.8090905@us.ibm.com> <1070674185.1929.9.camel@ibm-c.pdx.osdl.net> <1070907814.707.2.camel@ibm-c.pdx.osdl.net> <1071190292.1937.13.camel@ibm-c.pdx.osdl.net> <1071624314.1826.12.camel@ibm-c.pdx.osdl.net> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i586-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Daniel McNeil wrote: > > I have found something else that might be causing the problem. > filemap_fdatawait() skips pages that are not marked PG_writeback. > However, when a page is going to be written, PG_dirty is cleared > before PG_writeback is set (while the PG_locked is set). So it > looks like filemap_fdatawait() can see a page just before it is > going to be written and not wait for it. Here is a patch that > makes filemap_fdatawait() wait for locked pages as well to make > sure it does not missed any pages. This filemap_fdatawait() behaviour is as-designed. That function is only responsible for waiting on I/O which was initiated prior to it being invoked. Because it is designed for fsync(), fdatasync(), O_SYNC, msync(), sync(), etc. Now, it could be that this behaviour is not appropriate for the O_DIRECT sync function - the result of your testing will be interesting.