On Fri, Oct 22, 2021 at 12:49:15AM +0000, Jane Chu wrote:

I've looked through your "futher decouple DAX from block devices" series 
and likes the use of xarray in place of the host hash list.
Which upstream version is the series based upon?
If it's based on your development repo, I'd be happy to take a clone
and rebase my patches on yours if you provide a link. Please let me
know the best way to cooperate.

It is based on linux-next from when it was posted.  A git tree is here:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dax-block-cleanup

That said, I'm unclear at what you're trying to suggest with respect
to the 'DAXDEV_F_RECOVERY' flag.  The flag came from upper dax-fs
call stack to the dm target layer, and the dm targets are equipped
with handling pmem driver specific task, so it appears that the flag 
would need to be passed down to the native pmem layer, right?
Am I totally missing your point?

We'll need to pass it through (assuming we want to keep supporting
dm, see the recent discussion with Dan).

FYI, here is a sketch where I'd like to move to, but this isn't properly
tested yet:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dax-devirtualize

To support something like DAXDEV_F_RECOVERYwe'd need a separate
dax_operations methods.  Which to me suggest it probably should be
a different operation (fallocate / ioctl / etc) as Darrick did earlier.