| Message ID | 1631726561-16358-1-git-send-email-sandeen@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Remove DAX experimental warnings | expand |
On Wed, Sep 15, 2021 at 10:23 AM Eric Sandeen <sandeen@redhat.com> 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? [1]: https://lore.kernel.org/linux-xfs/CAPcyv4h0p+zD5tsT8HDUpNq_ZDCqo249KsmPLX-U8ia146r2Tg@mail.gmail.com/ [2]: https://lore.kernel.org/linux-xfs/CAPcyv4ic+LDagR8uF18tO3cCb6t=YTZNkAOK=vnsnERqY6Ze_g@mail.gmail.com/ [3]: https://lore.kernel.org/nvdimm/CAPcyv4hvzS1c01BweBkgDsjg=VGnaUUKi7b6j+1X=Rqzzm961Q@mail.gmail.com/
On 9/15/21 1:35 PM, Dan Williams wrote: > On Wed, Sep 15, 2021 at 10:23 AM Eric Sandeen <sandeen@redhat.com> 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? -Eric
On Wed, Sep 15, 2021 at 11:49 AM Eric Sandeen <sandeen@sandeen.net> wrote: > > On 9/15/21 1:35 PM, Dan Williams wrote: > > On Wed, Sep 15, 2021 at 10:23 AM Eric Sandeen <sandeen@redhat.com> 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.