[Libguestfs] [PATCH v2 4/4] v2v: in-place: request caps based on source config

[Roman Kagan]

In in-place mode, the decisions on which interfaces to use are made and
the source configuration is created by the outside entity.  So in that
case v2v needs to look it up in the source configuraion, and try to
follow.

For that, the source configuration is used to populate requested caps
object which is then passed to the convert routine.

Signed-off-by: Roman Kagan <rkagan at virtuozzo.com>
---

Notes:
    v2:
     - accept catch-all variants of source net and video as no preference

 v2v/types.mli |  6 +++---
 v2v/v2v.ml    | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/v2v/types.mli b/v2v/types.mli
index 0e40668..fbd45cf 100644
--- a/v2v/types.mli
+++ b/v2v/types.mli
@@ -66,7 +66,7 @@ and source_disk = {
 (** A source disk. *)
 
 and s_controller = Source_IDE | Source_SCSI | Source_virtio_blk
-(** Source disk controller.
+(** Source disk controller (in ascending order of preference).
 
     For the purposes of this field, we can treat virtio-scsi as
     [SCSI].  However we don't support conversions from virtio in any
@@ -88,7 +88,7 @@ and source_nic = {
   s_vnet_orig : string;                 (** Original network (if we map it). *)
   s_vnet_type : vnet_type;              (** Source network type. *)
 }
-(** Network adapter models. *)
+(** Network adapter models (in ascending order of preference). *)
 and s_nic_model = Source_other_nic of string |
                   Source_rtl8139 | Source_e1000 | Source_virtio_net
 (** Network interfaces. *)
@@ -108,7 +108,7 @@ and s_display_listen =
   | LAddress of string             (** Listen address. *)
   | LNetwork of string             (** Listen network. *)
 
-(** Video adapter model. *)
+(** Video adapter model (in ascending order of preference). *)
 and source_video = Source_other_video of string |
                    Source_Cirrus | Source_QXL
 
diff --git a/v2v/v2v.ml b/v2v/v2v.ml
index c828e48..608150f 100644
--- a/v2v/v2v.ml
+++ b/v2v/v2v.ml
@@ -82,11 +82,17 @@ let rec main () =
   );
 
   let keep_serial_console = output#keep_serial_console in
-  let rcaps = {
-                rcaps_block_bus = None;
-                rcaps_net_bus = None;
-                rcaps_video = None;
-              } in
+  let rcaps =
+    match conversion_mode with
+    | Copying (_, _) ->
+        {
+          rcaps_block_bus = None;
+          rcaps_net_bus = None;
+          rcaps_video = None;
+        }
+    | In_place ->
+        rcaps_from_source source
+  in
   let guestcaps = do_convert g inspect source keep_serial_console rcaps in
 
   g#umount_all ();
@@ -974,4 +980,43 @@ and preserve_overlays overlays src_name =
       printf (f_"Overlay saved as %s [--debug-overlays]\n") saved_filename
   ) overlays
 
+and rcaps_from_source source =
+  (* Request guest caps based on source configuration. *)
+
+  (* rely on s_controller enum being in ascending preference order, and None
+   * being smaller than Some anything *)
+  let best_block_type =
+    List.fold_left max None
+      (List.map (fun sd -> sd.s_controller) source.s_disks) in
+  let block_type =
+    match best_block_type with
+    | Some Source_virtio_blk -> Some Virtio_blk
+    | Some Source_SCSI -> None
+    | Some Source_IDE -> Some IDE
+    | None -> None in
+
+  (* rely on s_nic_model enum being in ascending preference order, and None
+   * being smaller than Some anything *)
+  let best_net_type =
+    List.fold_left max None
+      (List.map (fun nic -> nic.s_nic_model) source.s_nics) in
+  let net_type =
+    match best_net_type with
+    | Some Source_virtio_net -> Some Virtio_net
+    | Some Source_e1000 -> Some E1000
+    | Some Source_rtl8139 -> Some RTL8139
+    | Some Source_other_nic _ | None -> None in
+
+  let video =
+    match source.s_video with
+    | Some Source_QXL -> Some QXL
+    | Some Source_Cirrus -> Some Cirrus
+    | Some Source_other_video _ | None -> None in
+
+  {
+    rcaps_block_bus = block_type;
+    rcaps_net_bus = net_type;
+    rcaps_video = video;
+  }
+
 let () = run_main_and_handle_errors main
-- 
2.5.0