On Fri, Feb 26, 2021 at 11:05 AM Darrick J. Wong <djwong(a)kernel.org> wrote:
On Fri, Feb 26, 2021 at 09:45:45AM +0000, ruansy.fnst(a)fujitsu.com wrote:
> Hi, guys
> Beside this patchset, I'd like to confirm something about the
> "EXPERIMENTAL" tag for dax in XFS.
> In XFS, the "EXPERIMENTAL" tag, which is reported in waring message
> when we mount a pmem device with dax option, has been existed for a
> while. It's a bit annoying when using fsdax feature. So, my initial
> intention was to remove this tag. And I started to find out and solve
> the problems which prevent it from being removed.
> As is talked before, there are 3 main problems. The first one is "dax
> semantics", which has been resolved. The rest two are "RMAP for
> fsdax" and "support dax reflink for filesystem", which I have been
> working on.
> So, what I want to confirm is: does it means that we can remove the
> "EXPERIMENTAL" tag when the rest two problem are solved?
Yes. I'd keep the experimental tag for a cycle or two to make sure that
nothing new pops up, but otherwise the two patchsets you've sent close
those two big remaining gaps. Thank you for working on this!
> Or maybe there are other important problems need to be fixed before
> removing it? If there are, could you please show me that?
That remains to be seen through QA/validation, but I think that's it.
Granted, I still have to read through the two patchsets...
I've been meaning to circle back here as well.
My immediate concern is the issue Jason recently highlighted  with
respect to invalidating all dax mappings when / if the device is
ripped out from underneath the fs. I don't think that will collide
with Ruan's implementation, but it does need new communication from
driver to fs about removal events.