On Sat, Aug 11, 2018 at 08:50:49AM -0400, Brian Foster wrote: > On Fri, Aug 10, 2018 at 12:36:51PM -0700, Darrick J. Wong wrote: > > Technically we're not supposed to have flag days, but otoh this is a > > xfs-only ioctl for a feature that's still experimental, so perhaps it's > > not crucial to maintain compatibility with old kernels where the feature > > is incomplete and experimental? > > > > In my mind, I kind of take the experimental status as all bits/interface > may explode and are otherwise subject to change or disappear. Perhaps > others feel differently, it does seem we've kind of hinted towards the > contrary recently with respect to the per-inode dax bits and then now in > this discussion, but IMO that's kind of an inherent risk of doing > incremental work on complex features upstream. I've always considered that the experimental tag covers the user/ioctl interfaces as much as it does the functionality and on-disk format. i.e. like the on-disk format, the ioctl interfaces are subject to change until we clear the exp. tag, at which point they are essentially fixed forever. We /try/ not to have to change them after the initial merge, but sometimes we screw up and need to fix them before we commit to long term support. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
