Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:57274 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751848AbcFVQrP (ORCPT ); Wed, 22 Jun 2016 12:47:15 -0400 Date: Wed, 22 Jun 2016 09:47:15 -0700 From: Christoph Hellwig To: Trond Myklebust Cc: linux-nfs@vger.kernel.org Subject: Re: [PATCH v2 10/12] NFS: Do not serialise O_DIRECT reads and writes Message-ID: <20160622164715.GB16823@infradead.org> References: <1466544893-12058-1-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-2-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-3-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-4-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-5-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-6-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-7-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-8-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-9-git-send-email-trond.myklebust@primarydata.com> <1466544893-12058-10-git-send-email-trond.myklebust@primarydata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1466544893-12058-10-git-send-email-trond.myklebust@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, Jun 21, 2016 at 05:34:51PM -0400, Trond Myklebust wrote: > Allow dio requests to be scheduled in parallel, but ensuring that they > do not conflict with buffered I/O. Can you explain why we care about the full direct / bufferd exclusion that no other file system seems do be doing? I would have expected something more like the patch below, which follows the XFS locking model 1:1. This passed xfstests with plain NFSv4, haven't done any pNFS testing yet: ---