On Tue, Mar 12 2024 at 6:30P -0400, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > 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. Wow, using my 8+ year old commit message against me ;) I've honestly paged most of this out but I'll revisit, likely with Mikulas, to pin this down better and then see what possible.
