On Wed, Sep 15, 2021 at 11:49 AM Eric Sandeen <sandeen@xxxxxxxxxxx> wrote: > > On 9/15/21 1:35 PM, Dan Williams wrote: > > On Wed, Sep 15, 2021 at 10:23 AM Eric Sandeen <sandeen@xxxxxxxxxx> wrote: > >> > >> For six years now, when mounting xfs, ext4, or ext2 with dax, the drivers > >> have logged "DAX enabled. Warning: EXPERIMENTAL, use at your own risk." > >> > >> IIRC, dchinner added this to the original XFS patchset, and Dan Williams > >> followed suit for ext4 and ext2. > >> > >> After brief conversations with some ext4 and xfs developers and maintainers, > >> it seems that it may be time to consider removing this warning. > >> > >> For XFS, we had been holding out for reflink+dax capability, but proposals > >> which had seemed promising now appear to be indefinitely stalled, and > >> I think we might want to consider that dax-without-reflink is no longer > >> EXPERIMENTAL, while dax-with-reflink is simply an unimplemented future > >> feature. > > > > I do regret my gap in engagement since the last review as I got > > distracted by CXL, but I've recently gotten my act together and picked > > up the review again to help get Ruan's patches over the goal line [1]. > > I am currently awaiting Ruan's response to latest review feedback > > (looks like a new posting this morning). During that review Christoph > > identified some cleanups that would help Ruan's series, and those are > > now merged upstream [2]. The last remaining stumbling block (further > > block-device entanglements with dax-devices) I noted here [2]. The > > proposal is to consider eliding device-mapper dax-reflink support for > > now and proceed with just xfs-on-/dev/pmem until Mike, Jens, and > > Christoph can chime in on the future of dax on block devices. > > > > As far as I can see we have line of sight to land xfs-dax-reflink > > support for v5.16, does anyone see that differently at this point? > > Thanks for that update, Dan. I'm wondering, even if we have renewed > hopes and dreams for dax+reflink, would it make sense to go ahead and > declare dax without reflink non-experimental, and tag dax+reflink as > a new "EXPERIMENTAL feature if and when it lands? As I replied to the xfs patch in your series, I say "yes" EXPERIMENTAL can go now, because the concern was reflink support might regress dax-semantics wrt MAP_SYNC and the like. That concern seems to be avoided by the current direction.
