Re: [PATCH RFC] fhandle: expose u64 mount id to name_to_handle_at(2)

[Christoph Hellwig]

On Mon, May 20, 2024 at 05:35:49PM -0400, Aleksa Sarai wrote:
> Now that we have stabilised the unique 64-bit mount ID interface in
> statx, we can now provide a race-free way for name_to_handle_at(2) to
> provide a file handle and corresponding mount without needing to worry
> about racing with /proc/mountinfo parsing.

What are the guarantees for the mount ID?  Is it stable across reboots?
If not mixing it with file handles is a very bad idea.