On Tue, Apr 22, 2025 at 07:08:32AM +0100, John Garry wrote: > So consider userspace wants to write something atomically and we fail as a > HW-based atomic write is not possible. What is userspace going to do next? Exactly. > > I heard something like "if HW-based atomics are not possible, then > something has not been configured properly for the FS" - that something > would be extent granularity and alignment, but we don't have a method to > ensure this. That is the whole point of having a FS fallback. We now have the opt limit, right? (I'll review the reposted series ASAP, but for now I'll assume it) They can just tune their applications to it, and trigger on a trace point for the fallback to monitor it.