From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932617Ab1IAQPe (ORCPT ); Thu, 1 Sep 2011 12:15:34 -0400 Received: from fn.samba.org ([216.83.154.106]:52271 "EHLO lists.samba.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932570Ab1IAQPd (ORCPT ); Thu, 1 Sep 2011 12:15:33 -0400 Date: Thu, 1 Sep 2011 09:15:31 -0700 From: Jeremy Allison To: Christoph Hellwig Cc: Jeremy Allison , Ulrich Drepper , Andrew Morton , Daniel Ehrenberg , Jens Axboe , Jeff Moyer , linux-kernel@vger.kernel.org, linux-aio@kvack.org Subject: Re: Approaches to making io_submit not block Message-ID: <20110901161531.GB758@samba2> Reply-To: Jeremy Allison References: <20110830154157.d802d097.akpm@linux-foundation.org> <20110830155438.bc31ab99.akpm@linux-foundation.org> <20110830230342.GB16326@samba2> <20110830161130.592df746.akpm@linux-foundation.org> <4E5E152A.9050804@akkadia.org> <20110831165954.GC1611@samba2> <4E5F690C.4010209@akkadia.org> <20110901155845.GA758@samba2> <20110901160436.GA13556@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110901160436.GA13556@infradead.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 01, 2011 at 12:04:36PM -0400, Christoph Hellwig wrote: > On Thu, Sep 01, 2011 at 08:58:45AM -0700, Jeremy Allison wrote: > > Yes I did consider that of course. Problem is that leads you to the > > nightmare that is losing all fcntl locks on the file when any of the > > descriptors are closed. Of course we already have internal work arounds > > for that - but they're not scalable in this case. We'd have to dup on > > every read/write, and because of the fcntl lock problem we have to keep > > all fd's around until the final close of the file. Don't tell us to > > implement our own locking instead because (a) we already do in the case > > where we don't need locking consistency with NFS and (b) most vendors insist on > > locking consistency with NFS - not good if locks on one protocol aren't > > seen by another. > > We could easily give you an fcntl / dup3 flag to only release posix > locks on the final close of a struct file if that helps you. That would help us enormously - it'd be Linux only of course but we could easily add support for that. Can you propose the design here so we can run it past some of the Solaris/FreeBSD folks (it'd be nice if we could get broader adoption) ? Jeremy.