On Mon, 2024-05-27 at 15:17 +0200, Christian Brauner wrote: > > Returning the 64bit mount id makes this race-free because we now have > statmount(): > > u64 mnt_id = 0; > name_to_handle_at(AT_FDCWD, "/path/to/file", &handle, &mnt_id, 0); > statmount(mnt_id); > > Which gets you the device number which one can use to figure out the > uuid without ever having to open a single file (We could even expose > the > UUID of the filesystem through statmount() if we wanted to.). > It is not race free. statmount() depends on the filesystem still being mounted somewhere in your namespace, which is not guaranteed above. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
