CIFS: Add transform header handling callbacks

We need to recognize and parse transformed packets in demultiplex
thread to find a corresponsing mid and process it further.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index b84febf..35faa6c 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -872,12 +872,19 @@ cifs_demultiplex_thread(void *p)
 			continue;
 		server->total_read += length;
 
-		mid_entry = server->ops->find_mid(server, buf);
+		if (server->ops->is_transform_hdr &&
+		    server->ops->receive_transform &&
+		    server->ops->is_transform_hdr(buf)) {
+			length = server->ops->receive_transform(server,
+								&mid_entry);
+		} else {
+			mid_entry = server->ops->find_mid(server, buf);
 
-		if (!mid_entry || !mid_entry->receive)
-			length = standard_receive3(server, mid_entry);
-		else
-			length = mid_entry->receive(server, mid_entry);
+			if (!mid_entry || !mid_entry->receive)
+				length = standard_receive3(server, mid_entry);
+			else
+				length = mid_entry->receive(server, mid_entry);
+		}
 
 		if (length < 0)
 			continue;