> Back to your earlier point though: > > Is a global offset really a non-starter? I can see about doing something > per-superblock, but ktime_get_mg_coarse_ts64 should be roughly as cheap > as ktime_get_coarse_ts64. I don't see the downside there for the non- > multigrain filesystems to call that. I have to say that this doesn't excite me. This whole thing feels a bit hackish. I think that a change version is the way more sane way to go. > > On another note: maybe I need to put this behind a Kconfig option > initially too? So can we for a second consider not introducing fine-grained timestamps at all. We let NFSv3 live with the cache problem it's been living with forever. And for NFSv4 we actually do introduce a proper i_version for all filesystems that matter to it. What filesystems exactly don't expose a proper i_version and what does prevent them from adding one or fixing it?
