On Thu, Apr 21, 2022 at 12:47 AM Dave Chinner <da...@fromorbit.com> wrote: > > On Wed, Apr 20, 2022 at 10:54:59PM -0700, Christoph Hellwig wrote: > > On Thu, Apr 21, 2022 at 02:35:02PM +1000, Dave Chinner wrote: > > > Sure, I'm not a maintainer and just the stand-in patch shepherd for > > > a single release. However, being unable to cleanly merge code we > > > need integrated into our local subsystem tree for integration > > > testing because a patch dependency with another subsystem won't gain > > > a stable commit ID until the next merge window is .... distinctly > > > suboptimal. > > > > Yes. Which is why we've taken a lot of mm patchs through other trees, > > sometimes specilly crafted for that. So I guess in this case we'll > > just need to take non-trivial dependencies into the XFS tree, and just > > deal with small merge conflicts for the trivial ones. > > OK. As Naoyo has pointed out, the first dependency/conflict Ruan has > listed looks trivial to resolve. > > The second dependency, OTOH, is on a new function added in the patch > pointed to. That said, at first glance it looks to be independent of > the first two patches in that series so I might just be able to pull > that one patch in and have that leave us with a working > fsdax+reflink tree. > > Regardless, I'll wait to see how much work the updated XFS/DAX > reflink enablement patchset still requires when Ruan posts it before > deciding what to do here. If it isn't going to be a merge > candidate, what to do with this patchset is moot because there's > little to test without reflink enabled...
I do have a use case for this work absent the reflink work. Recall we had a conversation about how to communicate "dax-device has been ripped away from the fs" events and we ended up on the idea of reusing ->notify_failure(), but with the device's entire logical address range as the notification span. That will let me unwind and delete the PTE_DEVMAP infrastructure for taking extra device references to hold off device-removal. Instead ->notify_failure() arranges for all active DAX mappings to be invalidated and allow the removal to proceed especially since physical removal does not care about software pins.
