CA-414651 Fix device rename in PIF after RPU

After RPU from legacy network device name, the name in PIF
object should be updated. The new network device name is
in interface_tables.device_to_position_table. The position
of old device name in PIF object can be get by its associated
bridge and then correspond with the new name.
In this procedure, a exsiting bridge is used to get the position.
However, the bridge is used to update MTU. It is specially
handled when the device is under a bond. The bridge is actually
the parent bond bridge. This leads to no position is found for
old device name and then device name is not updated correctly.
Fix: use the associated bridge to find the position.

Signed-off-by: Changlei Li <changlei.li@cloud.com>

Author: changlei-li

ocaml/xapi/xapi_pif.ml

@@ -48,6 +48,13 @@ let bridge_naming_convention (device : string) (pos_opt : int option) =
 let n_of_xenbrn_opt bridge =
   try Scanf.sscanf bridge "xenbr%d%!" Option.some with _ -> None
 
+let get_pif_position ~__context pif =
+  if pif.API.pIF_physical then
+    let bridge = Db.Network.get_bridge ~__context ~self:pif.API.pIF_network in
+    n_of_xenbrn_opt bridge
+  else
+    None
+
 type tables = {
     device_to_position_table: (string * int) list
   ; device_to_mac_table: (string * string) list
@@ -133,15 +140,12 @@ let refresh_internal ~__context ~interface_tables ~self =
   (* Pif device name maybe change. Look up device_to_position table to get the
      new device name. *)
   let pif_device_name =
-    if pif.API.pIF_physical then (
-      match n_of_xenbrn_opt bridge with
-      | Some position ->
-          find_name_by_position position pif.API.pIF_device
-      | None ->
-          info "PIF %s: no position found for this device" pif.API.pIF_device ;
-          pif.API.pIF_device
-    ) else
-      pif.API.pIF_device
+    match get_pif_position ~__context pif with
+    | Some position ->
+        find_name_by_position position pif.API.pIF_device
+    | None ->
+        info "PIF %s: no position found for this device" pif.API.pIF_device ;
+        pif.API.pIF_device
   in
   (* Update the specified PIF field in the database, if
    * and only if a corresponding value can be read from