On Wed, Aug 30, 2017 at 12:00:59PM +0200, Jan Kara wrote:

/dev/ram0 /mnt xfs rw,relatime,attr2,dax,inode64,noquota 0 0

marvin5:~/:[0]# ls /mnt/
fsxfile  fsxfile.fsxgood  fsxfile.fsxlog

marvin5:~/:[0]# ./xfsprogs-dev/io/xfs_io -c 'lsattr' /mnt/fsxfile
-p-------------- /mnt/fsxfile 

marvin5:~/:[0]# ./xfsprogs-dev/io/xfs_io -c 'chattr +x' /mnt/fsxfile

marvin5:~/:[0]# ./xfsprogs-dev/io/xfs_io -c 'lsattr' /mnt/fsxfile
-p-------------- /mnt/fsxfile 

No DAX flag set and no error... What am I doing wrong?

Odd.  Even on a non-DAX device the flag sticks for me:

root@testvm:~# mount /dev/sda /mnt/
root@testvm:~# touch foo
root@testvm:~# cd /mnt/
root@testvm:/mnt# xfs_io -c 'chattr +x' foo
root@testvm:/mnt# xfs_io -c 'lsattr' foo
--------------x- foo