Return-Path: Received: from casper.infradead.org ([85.118.1.10]:54783 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752007AbcB2J6D (ORCPT ); Mon, 29 Feb 2016 04:58:03 -0500 Date: Mon, 29 Feb 2016 10:57:56 +0100 From: Christoph Hellwig To: Kinglong Mee Cc: Trond Myklebust , "linux-nfs@vger.kernel.org" Subject: Re: [PATCH] nfs/blocklayout: make sure making a aligned read request Message-ID: <20160229095756.GA19397@infradead.org> References: <56BF34E3.1020003@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <56BF34E3.1020003@gmail.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sat, Feb 13, 2016 at 09:51:31PM +0800, Kinglong Mee wrote: > Only treat write goes up to the inode size as aligned request, > because it always write PAGE_CACHE_SIZE, but read a dynamic size. Can you explain what the point is? We'll never use data pas the block size in the page cache, but per the block size requirement in the spec we must be able to read it. This patch means we can't direct storage reads where we previously could, without any obvious upside.