On Wed, May 29, 2024 at 09:40:01AM +0200, Christian Brauner wrote: > Yeah, that's exactly what I figured and no that's not something we > should do. > > Not just can have a really large number of superblocks if you have mount > namespaces and large container workloads that interface also needs to be > highly privileged. Again, that would be the most trivial POC. We can easily do hash. > Plus, you do have filesystems like btrfs that can be mounted multiple > times with the same uuid. Which doesn't matter. Just like for NFS file handles the fs identifier identifier plus the file part of the file handle need to be unique. > And in general users will still need to be able to legitimately use a > mount fd and not care about the handle type used with it. I don't understand what you mean. If we hand out file handles with fsid that of course needs to be keyed off a new flag for both name_to_handle and open_by_hnalde that makes them not interchangable to handles generated without that flag.