On Thu, 28 Sept 2023 at 15:03, Miklos Szeredi <mszeredi@xxxxxxxxxx> wrote: > > If a mount is released then its mnt_id can immediately be reused. This is > bad news for user interfaces that want to uniquely identify a mount. > > Implementing a unique mount ID is trivial (use a 64bit counter). > Unfortunately userspace assumes 32bit size and would overflow after the > counter reaches 2^32. > > Introduce a new 64bit ID alongside the old one. Initialize the counter to > 2^32, this guarantees that the old and new IDs are never mixed up. It occurred to me that it might make sense to make this counter per-namespace. That would allow more separation between namespaces, like preventing the observation of mount creations in other namespaces. Does a global number make any sense? Thanks, Miklos
