From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932592Ab1IAQFB (ORCPT ); Thu, 1 Sep 2011 12:05:01 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:53216 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932452Ab1IAQE6 (ORCPT ); Thu, 1 Sep 2011 12:04:58 -0400 Date: Thu, 1 Sep 2011 12:04:36 -0400 From: Christoph Hellwig To: Jeremy Allison Cc: 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: <20110901160436.GA13556@infradead.org> References: <4E5D64E8.7000102@kernel.dk> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110901155845.GA758@samba2> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.