s3:smbd: split out some generic code from close_remove_share_mode()
close_share_mode_lock_prepare() will operates on share_mode_lock
in order to check if the object needs to be deleted or if
we can remove the share_mode_entry directly.
close_share_mode_lock_cleanup() will finish after the object
has been deleted.
We can reuse these function in close_directory() soon and
in the end we'll avoid get_existing_share_mode_lock()
and call them via share_mode_entry_prepare_{lock,unlock}(),
so that they can run under a tdb chainlock.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>