From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Layton Subject: Re: stable page writes: wait_on_page_writeback and packet signing Date: Wed, 9 Mar 2011 18:45:42 -0500 Message-ID: <20110309184542.07c5ffe6@corrin.poochiereds.net> References: <20110309215148.GW15097@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Steve French , linux-cifs@vger.kernel.org, linux-fsdevel , Mingming Cao To: Dave Chinner Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50936 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752274Ab1CIXpu (ORCPT ); Wed, 9 Mar 2011 18:45:50 -0500 In-Reply-To: <20110309215148.GW15097@dastard> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, 10 Mar 2011 08:51:48 +1100 Dave Chinner wrote: > > Sounds like a case for the same dirty page lifecycle as NFS: clean > -> dirty -> writeback -> unstable -> clean. i.e. the page is > unstable after the issuing of the IO until the response from the > server so the page can't be reclaimed while the IO is still in > progress at the server... > It's a little more complicated than that for NFS. Unstable pages are ones that have had successful writes but that have not been committed yet. Once a NFS COMMIT call completes, the page is marked clean and can be freed by the VM. Actual writeback in NFS is pretty similar to other filesystems -- the page is only under writeback until the WRITE response is received. It just doesn't clear the dirty bit until a COMMIT response is received. That said, an unstable write model for CIFS is not a bad idea. Just substitute a SMB_COM_FLUSH for a NFS COMMIT call... -- Jeff Layton