Re: [PATCH RFC v2] fhandle: expose u64 mount id to name_to_handle_at(2)

On Mon, May 27, 2024 at 03:38:40PM +0000, Trond Myklebust wrote:

quoted

It
does not matter what mount you use to access it.

Sure. However if you are providing a path argument, then presumably you
need to know which file system (aka super_block) it eventually resolves
to.

Except that you can't, at least not without running into potential
races.  The only way to fix a race vs unmount/remount is to include
the fsid part in the kernel generated file handle.

If your use case isn't NFS servers, then what use case are you
targeting, and how do you expect those applications to use this API?

The main user of the open by handle syscalls seems to be fanotify
magic.