Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751821AbbLXM1F (ORCPT ); Thu, 24 Dec 2015 07:27:05 -0500 Received: from g4t3426.houston.hp.com ([15.201.208.54]:8319 "EHLO g4t3426.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750905AbbLXM1D convert rfc822-to-8bit (ORCPT ); Thu, 24 Dec 2015 07:27:03 -0500 From: "Elliott, Robert (Persistent Memory)" To: Christoph Hellwig CC: Cholerae Hu , Dan Williams , Dave Chinner , Ted Tso , "adilger.kernel@dilger.ca" , "linux-nvdimm@lists.01.org" , "linux-ext4@vger.kernel.org" , "xfs@oss.sgi.com" , "linux-kernel@vger.kernel.org" Subject: RE: A blocksize problem about dax and ext4 Thread-Topic: A blocksize problem about dax and ext4 Thread-Index: AQHRPXn8bxToPOnbsUmlb/yBrXUup57Y0FsAgAA5STCAADeRgIAACZyAgAAGkACAABtSgIAAAlzAgAB80ICAACTYoA== Date: Thu, 24 Dec 2015 12:26:18 +0000 Message-ID: <94D0CD8314A33A4D9D801C0FE68B40295BEDCB5E@G9W0745.americas.hpqcorp.net> References: <94D0CD8314A33A4D9D801C0FE68B40295BEC985F@G9W0745.americas.hpqcorp.net> <20151224000021.GU19802@dastard> <94D0CD8314A33A4D9D801C0FE68B40295BEC9CDD@G9W0745.americas.hpqcorp.net> <20151224101111.GA6438@infradead.org> In-Reply-To: <20151224101111.GA6438@infradead.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [16.210.192.232] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1155 Lines: 33 > -----Original Message----- > From: Christoph Hellwig [mailto:hch@infradead.org] > Sent: Thursday, December 24, 2015 4:11 AM > Subject: Re: A blocksize problem about dax and ext4 > > On Thu, Dec 24, 2015 at 02:47:07AM +0000, Elliott, Robert (Persistent > Memory) wrote: > > > Did you mean that I should make the blocksize bigger until the mount > > > command tell me that dax is enabled? > > > > To really use DAX, the filesystem block size must match the > > system CPU's page size, which is probably 4096 bytes. > > No, it doesn't. File you use for DAX must be aligne at page size > granularity. For XFS you could do this with the per-inode extent > size hint for example even if the overall block size is smaller. I think that's a future goal. Currently, the checks are like this: if (sb->s_blocksize != PAGE_SIZE) { xfs_alert(mp, "Filesystem block size invalid for DAX Turning DAX off."); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/