From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock ASAP Date: Sun, 9 Oct 2016 08:17:48 -0700 Message-ID: <20161009151748.GA29102@infradead.org> References: <1471554672-38662-1-git-send-email-Waiman.Long@hpe.com> <1471554672-38662-3-git-send-email-Waiman.Long@hpe.com> <20161006181718.GA14967@linux-80c1.suse> <20161006214751.GU27872@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20161006214751.GU27872@dastard> Sender: linux-doc-owner@vger.kernel.org To: Dave Chinner Cc: Davidlohr Bueso , Waiman Long , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, Jason Low , Jonathan Corbet , Scott J Norton , Douglas Hatch List-Id: linux-arch.vger.kernel.org On Fri, Oct 07, 2016 at 08:47:51AM +1100, Dave Chinner wrote: > Except that it's DAX, and in 4.7-rc1 that used shared locking at the > XFS level and never took exclusive locks. > > *However*, the DAX IO path locking in XFS has changed in 4.9-rc1 to > match the buffered IO single writer POSIX semantics - the test is a > bad test based on the fact it exercised a path that is under heavy > development and so can't be used as a regression test across > multiple kernels. That being said - I wonder if we should allow the shared lock on DAX files IFF the user is specifying O_DIRECT in the open mode.. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:60467 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751385AbcJIPRw (ORCPT ); Sun, 9 Oct 2016 11:17:52 -0400 Date: Sun, 9 Oct 2016 08:17:48 -0700 From: Christoph Hellwig Subject: Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock ASAP Message-ID: <20161009151748.GA29102@infradead.org> References: <1471554672-38662-1-git-send-email-Waiman.Long@hpe.com> <1471554672-38662-3-git-send-email-Waiman.Long@hpe.com> <20161006181718.GA14967@linux-80c1.suse> <20161006214751.GU27872@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161006214751.GU27872@dastard> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dave Chinner Cc: Davidlohr Bueso , Waiman Long , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, Jason Low , Jonathan Corbet , Scott J Norton , Douglas Hatch Message-ID: <20161009151748.77nbi39rsXBaF4cp0oxKntzKao2ol1bt2w3J5pm6Zhg@z> On Fri, Oct 07, 2016 at 08:47:51AM +1100, Dave Chinner wrote: > Except that it's DAX, and in 4.7-rc1 that used shared locking at the > XFS level and never took exclusive locks. > > *However*, the DAX IO path locking in XFS has changed in 4.9-rc1 to > match the buffered IO single writer POSIX semantics - the test is a > bad test based on the fact it exercised a path that is under heavy > development and so can't be used as a regression test across > multiple kernels. That being said - I wonder if we should allow the shared lock on DAX files IFF the user is specifying O_DIRECT in the open mode..