From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 6814D81ECF for ; Sun, 22 Jan 2017 08:29:12 -0800 (PST) Date: Sun, 22 Jan 2017 17:29:10 +0100 From: Christoph Hellwig Subject: Re: [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Message-ID: <20170122162910.GA5267@lst.de> References: <148488421301.37913.12835362165895864897.stgit@dwillia2-desk3.amr.corp.intel.com> <20170121175212.GA28180@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Matthew Wilcox Cc: Jens Axboe , Tony Luck , Jan Kara , Mike Snitzer , "linux-nvdimm@lists.01.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Ingo Molnar , Thomas Gleixner , Al Viro , "H. Peter Anvin" , "linux-fsdevel@vger.kernel.org" , "dm-devel@redhat.com" , Linus Torvalds , Christoph Hellwig List-ID: On Sun, Jan 22, 2017 at 03:43:09PM +0000, Matthew Wilcox wrote: > In the case of a network filesystem being used to communicate with > a different VM on the same physical machine, there is no backing > device, just a network protocol. Again, do you mean block device? For a filesystem that does not do any pagecache writeback we already don't need a backing device, so I don't really see an issue there to start with. > I'm not terribly enthusiastic about creating a fake block device to > sit on top of a network filesystem, but I suppose we could go that > way if we had to. I see no need to a new network filesystem to have a fake block device. We do need a fake block device for an unchanged or partial DAX aware file system. And those are the only ones we have at the moment, although XFS could be converted to do direct calls bypassing the block layer fairly trivially if needed. For ext2 and ext4 that would be much harder due to the buffer cache dependency. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm