On Sat, Sep 10, 2016 at 07:52:53AM +0000, Matthew Wilcox wrote:

DAX code over to using iomap requires converting all of ext2 away from
buffer_head; are you saying he's wrong?

Not sure if he's really saying that, but it's wrong for sure.  Just
to prove that I came up with a working ext2 iomap DAX implementation
in a few hours today.  I'll take a stab at ext4 and the block device
as well and will post the updated series early next week - I'll need
to take care of a few high priority todo list items first.