Project ids are only settable filesystem wide in the initial namespace.
They don't take the mount's idmapping into account.
Note, that after we converted everything over to struct mnt_idmap
mistakes such as the one here aren't possible anymore as struct
mnt_idmap cannot be passed to functions that operate on k{g,u}ids.
Acked-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>