On Tue, Mar 12, 2024 at 06:22:21PM -0400, Mike Snitzer wrote: > > The real problem is that we combine the limits while we shouldn't. > > Every since we've supported immutable biovecs and do the splitting > > down in blk-mq there is no point to even inherit such limits in the > > upper drivers. > > immutable biovecs, late splitting and blk-mq aren't a factor. > > dm-crypt has to contend with the crypto subsystem and HW crypto > engines that have their own constraints. Yes, they are. The limit for underlying device does not matter for an upper devіce as it will split later. And that's not just my opinion, you also clearly stated that in the commit adding the limits (586b286b110e94e). We should have stopped inheriting all these limits only relevant for splitting when we switched to immutable bvecs. I don't know why we didn't, but a big part of that might be that we never made clear which limits these are.
