Darrick, After reading the comments from you, Dave Chinner, and Dan, it looks like the dyanmic S_DAX flag support won't be coming or not any time soon at the least. Here are the the collection of patches so far to address yours and Dave C's comments for minimal support. Please let me know what else I am missing. Thanks! v3: - Removed setting of error return in ext2 and ext4 per Ross's comments - Rebased against 4.16-rc1 with updates --- Darrick J. Wong (1): fs: allow per-device dax status checking for filesystems Dave Jiang (2): dax: change bdev_dax_supported() to support boolean returns xfs: reject removal of realtime flag when datadev doesn't support DAX drivers/dax/super.c | 27 ++++++++++++++------------- fs/ext2/super.c | 3 +-- fs/ext4/super.c | 3 +-- fs/xfs/xfs_ioctl.c | 18 +++++++++++++++++- fs/xfs/xfs_iops.c | 30 +++++++++++++++++++++++++----- fs/xfs/xfs_super.c | 11 +++++++++-- include/linux/dax.h | 18 +++++++++++++----- 7 files changed, 80 insertions(+), 30 deletions(-) --