From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH v11 54/63] dax: Hash on XArray instead of mapping Date: Mon, 21 May 2018 03:25:24 -0700 Message-ID: <20180521102524.GB20878@bombadil.infradead.org> References: <20180414141316.7167-1-willy@infradead.org> <20180414141316.7167-55-willy@infradead.org> <20180521044756.GD27043@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1fKi0n-0006aj-Kg for linux-f2fs-devel@lists.sourceforge.net; Mon, 21 May 2018 10:25:53 +0000 Received: from bombadil.infradead.org ([198.137.202.133]) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1fKi0m-00FKen-Aq for linux-f2fs-devel@lists.sourceforge.net; Mon, 21 May 2018 10:25:53 +0000 Content-Disposition: inline In-Reply-To: <20180521044756.GD27043@linux.intel.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Ross Zwisler , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Matthew Wilcox , Jan Kara , Jeff Layton , Lukas Czerner , Christoph Hellwig , Goldwyn Rodrigues , Nicholas Piggin , Ryusuke Konishi , linux-nilfs@vger.kernel.org, Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net, Oleg Drokin , Andreas Dilger , James Simmons , Mike Kravetz On Sun, May 20, 2018 at 10:47:56PM -0600, Ross Zwisler wrote: > On Sat, Apr 14, 2018 at 07:13:07AM -0700, Matthew Wilcox wrote: > > From: Matthew Wilcox > > > > Since the XArray is embedded in the struct address_space, this contains > > exactly as much entropy as the address of the mapping. > > I agree that they both have the same amount of entropy, but what's the > benefit? It doesn't seem like this changes any behavior, fixes any bugs or > makes things any simpler? This is a preparatory patch for some of the changes later in the series. It has no benefit in and of itself; the benefit comes later when we switch from dax_wake_mapping_entry() to dax_wake_entry(): static void dax_wake_entry(struct xa_state *xas, bool wake_all) This switch could be left until the end; I can introduce dax_wake_entry() without this change: +static void dax_wake_entry(struct xa_state *xas, bool wake_all) +{ + struct address_space *mapping = container_of(xas->xa, + struct address_space, i_pages); + return dax_wake_mapping_entry_waiter(mapping, xas->xa_index, NULL, + wake_all); +} and then cut everybody over in the final step. Or I can just explain in the changelog that it's a preparatory step. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot