From: Theodore Ts'o Subject: Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Date: Mon, 29 Aug 2016 08:57:41 -0400 Message-ID: <20160829125741.cdnbb2uaditcmnw2@thunk.org> References: <20160823220419.11717-1-ross.zwisler@linux.intel.com> <20160823220419.11717-3-ross.zwisler@linux.intel.com> <20160825075728.GA11235@infradead.org> <20160826212934.GA11265@linux.intel.com> <20160829074116.GA16491@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Matthew Wilcox , linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org, Dave Chinner , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andreas Dilger , Alexander Viro , Jan Kara , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton To: Christoph Hellwig Return-path: Content-Disposition: inline In-Reply-To: <20160829074116.GA16491-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On Mon, Aug 29, 2016 at 12:41:16AM -0700, Christoph Hellwig wrote: > > We're going to move forward killing buffer_heads in XFS. I think ext4 > would dramatically benefit from this a well, as would ext2 (although I > think all that DAX work in ext2 is a horrible idea to start with). It's been on my todo list. The only reason why I haven't done it yet is because I knew you were working on a solution, and I didn't want to do things one way for buffered I/O, and a different way for Direct I/O, and disentangling the DIO code and the different assumptions of how different file systems interact with the DIO code is a *mess*. It may have gotten better more recently, but a few years ago I took a look at it and backed slowly away..... - Ted