From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Zwisler Subject: Re: [PATCH v11 54/63] dax: Hash on XArray instead of mapping Date: Tue, 22 May 2018 15:38:22 -0600 Message-ID: <20180522213822.GA12733@linux.intel.com> References: <20180414141316.7167-1-willy@infradead.org> <20180414141316.7167-55-willy@infradead.org> <20180521044756.GD27043@linux.intel.com> <20180521102524.GB20878@bombadil.infradead.org> 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-2.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1fLEzK-0004Qy-9Q for linux-f2fs-devel@lists.sourceforge.net; Tue, 22 May 2018 21:38:34 +0000 Received: from mga06.intel.com ([134.134.136.31]) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1fLEzF-00DFSF-KF for linux-f2fs-devel@lists.sourceforge.net; Tue, 22 May 2018 21:38:34 +0000 Content-Disposition: inline In-Reply-To: <20180521102524.GB20878@bombadil.infradead.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Matthew Wilcox Cc: linux-nilfs@vger.kernel.org, Jan Kara , Jeff Layton , Matthew Wilcox , James Simmons , Jaegeuk Kim , Andreas Dilger , Nicholas Piggin , linux-f2fs-devel@lists.sourceforge.net, Oleg Drokin , linux-mm@kvack.org, Ryusuke Konishi , linux-fsdevel@vger.kernel.org, Lukas Czerner , Ross Zwisler , Christoph Hellwig , Goldwyn Rodrigues , Mike Kravetz On Mon, May 21, 2018 at 03:25:24AM -0700, Matthew Wilcox wrote: > 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. Sure, just a note in the changelog saying that it's a preparatory step would be good enough for me. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot