smb: client: introduce close_cached_dir_locked()

smb: client: introduce close_cached_dir_locked()

Replace close_cached_dir() calls under cfid_list_lock with a new
close_cached_dir_locked() variant that uses kref_put() instead of
kref_put_lock() to avoid recursive locking when dropping references.

While the existing code works if the refcount >= 2 invariant holds,
this area has proven error-prone. Make deadlocks impossible and WARN
on invariant violations.

Cc: stable@vger.kernel.org
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>