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Date: Sun, 20 May 2018 22:47:56 -0600
From: Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH v11 54/63] dax: Hash on XArray instead of mapping
Message-ID: <20180521044756.GD27043@linux.intel.com>
References: <20180414141316.7167-1-willy@infradead.org>
 <20180414141316.7167-55-willy@infradead.org>
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To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Matthew Wilcox <mawilcox@microsoft.com>, Jan Kara <jack@suse.cz>, Jeff Layton <jlayton@redhat.com>, Lukas Czerner <lczerner@redhat.com>, Ross Zwisler <ross.zwisler@linux.intel.com>, Christoph Hellwig <hch@lst.de>, Goldwyn Rodrigues <rgoldwyn@suse.com>, Nicholas Piggin <npiggin@gmail.com>, Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>, linux-nilfs@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <yuchao0@huawei.com>, linux-f2fs-devel@lists.sourceforge.net, Oleg Drokin <oleg.drokin@intel.com>, Andreas Dilger <andreas.dilger@intel.com>, James Simmons <jsimmons@infradead.org>, Mike Kravetz <mike.kravetz@oracle.com>

On Sat, Apr 14, 2018 at 07:13:07AM -0700, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
> 
> 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?