Return-Path: linux-nfs-owner@vger.kernel.org Received: from verein.lst.de ([213.95.11.211]:35130 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753416AbaHGLZm (ORCPT ); Thu, 7 Aug 2014 07:25:42 -0400 Date: Thu, 7 Aug 2014 13:25:37 +0200 From: Christoph Hellwig To: Peng Tao Cc: Christoph Hellwig , Trond Myklebust , linuxnfs , "faibish, sorin" Subject: Re: [PATCH 08/17] pnfs/blocklayout: reject pnfs blocksize larger than page size Message-ID: <20140807112537.GA3437@lst.de> References: <1407396229-4785-1-git-send-email-hch@lst.de> <1407396229-4785-9-git-send-email-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Aug 07, 2014 at 06:43:14PM +0800, Peng Tao wrote: > So this kills EMC server support. Given the state the code claiming support for any server is a large exaggeration.. > Can you please share what kind of > badly deadlock you saw with large block size support? The read-modify write code (which I'll remove later) can lock arbitary numbers of additional pages from the writeback back code without doing a trylock, which is required for doing this in page writeback. Note that it's not a deadlock, but I can also trivіally corrupt data in those pages as it doesn't lock against them, you just need a race window where it's modified after writeback has been started for a large extents, which isn't too hard to hit with tools like fsstress.