vfs_crossrename not working in samba-4.15.*

[Pavel Filipenský]

small edits:
>
> So we have two requirements that do not go together really well:
>
> 1) make crossrename stackable using VFS ops
>
(needs simultaneously two locks)
>
> 2) keep the share mode locking safee locks. /
> /
>
(prohibits having simultaneously two locks)

> Maybe copy_reg can be improved or do you see any serious problem with it?
>
Maybe copy_internals() can be improved or do you see any serious problem 
with it?