From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 25 May 2001 15:03:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 25 May 2001 15:03:24 -0400 Received: from nat-pool-meridian.redhat.com ([199.183.24.200]:37078 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id ; Fri, 25 May 2001 15:03:07 -0400 Date: Fri, 25 May 2001 20:02:53 +0100 From: "Stephen C. Tweedie" To: Alexander Viro Cc: Linus Torvalds , "Eric W. Biederman" , "Stephen C. Tweedie" , linux-kernel@vger.kernel.org Subject: Re: DVD blockdevice buffers Message-ID: <20010525200253.M7952@redhat.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from viro@math.psu.edu on Fri, May 25, 2001 at 02:24:52PM -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, May 25, 2001 at 02:24:52PM -0400, Alexander Viro wrote: > If you are OK with adding two extra arguments to ->readpage() I could > submit a patch replacing that with plain and simple page cache by tomorrow. > It should not be a problem to port, but I want to get some sleep before > testing it... The problem will be returning the IO completion status. We can't just rely on PG_Error: what happens if two separate partial reads are submitted at once within the same page, yet the page is not completely in cache? If we forced readpage to be synchronous in that case we could just return the status directly. Otherwise we need a separate way of determining the completion status once the page becomes unlocked (eg. have a special readpage return which means "all done, completion status is X", and resubmit the readpage to get that completion status once the page lock is dropped.) --Stephen