From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 483FE7CA6 for ; Wed, 17 Feb 2016 16:56:58 -0600 (CST) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id 36C588F8049 for ; Wed, 17 Feb 2016 14:56:58 -0800 (PST) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by cuda.sgi.com with ESMTP id eGUG2w7wPiMGUy0H for ; Wed, 17 Feb 2016 14:56:57 -0800 (PST) Date: Wed, 17 Feb 2016 15:56:45 -0700 From: Ross Zwisler Subject: Re: [PATCH 0/4] xfs: fixes for XFS_DIFLAG2_DAX support Message-ID: <20160217225645.GD30126@linux.intel.com> References: <1455513734-15192-1-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1455513734-15192-1-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: ross.zwisler@linux.intel.com, jack@suse.cz, xfs@oss.sgi.com On Mon, Feb 15, 2016 at 04:22:10PM +1100, Dave Chinner wrote: > Hi folks, > > This is a series to add the correct constraints to using the on-disk > inode flag to enable DAX on per-file basis. The same constraints are > placed on setting the flag on directories for inheritance purposes. > > These constraints are: > - the inode flag is limited to regular files or directory > inodes. > - the S_DAX flag is only ever set on regular files > - the flag can only ever be set on filesystems which have > blocksize == PAGE_SIZE (for now) > - When the flag is set or cleared, the current mapping > contents are flushed and then invalidated so that the new > access mode starts with an empty mapping. > - Setting or clearing the flag is atomic w.r.t. IO and > page faults. > > I've tested these manually with xfs_io (patchset for supporting > chattr +x/-x to be sent soon), and it all appears to work as > expected. I'd like to push these for 4.5-rc6 so the initial kernel > with support for this flag doesn't do silly things, so comments, > testing and review woul dbe appreciated. > > Cheers, > > Dave. This seems like what we want to be doing for raw block devices, when we add back in support. Default to DAX off so we have to opt-in, and when we get an IOCTL to enable them block I/O and page faults, clear out all mappings and radix tree entries, and then change the flag and turn back on I/O and page faults. We'll also need to add a check to prevent mounts on raw block devices with S_DAX set. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs