From 9b1984eb3ce4411b1a1882cddc263766b3984ba0 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Mon, 20 Oct 2014 18:21:38 +0100
Subject: [PATCH] v2v: Add input#adjust_overlay_parameters method.

This is called before the copying phase to allow the input method to
adjust overlay/backing parameters.

The default implementation does nothing, so this commit has no effect.

(cherry picked from commit 0084736f5fe75f62f72f0014333b32ab753b1554)
---
 v2v/types.ml  | 1 +
 v2v/types.mli | 3 +++
 v2v/v2v.ml    | 7 +++++++
 3 files changed, 11 insertions(+)

diff --git a/v2v/types.ml b/v2v/types.ml
index 5124f3c..c5a05f6 100644
--- a/v2v/types.ml
+++ b/v2v/types.ml
@@ -194,6 +194,7 @@ and guestcaps_video_type = QXL | Cirrus
 class virtual input verbose = object
   method virtual as_options : string
   method virtual source : unit -> source
+  method adjust_overlay_parameters (_ : overlay) = ()
 end
 
 class virtual output verbose = object
diff --git a/v2v/types.mli b/v2v/types.mli
index c077dc2..2123a41 100644
--- a/v2v/types.mli
+++ b/v2v/types.mli
@@ -143,6 +143,9 @@ class virtual input : bool -> object
       This is just used for pretty-printing log messages. *)
   method virtual source : unit -> source
   (** Examine the source hypervisor and create a source struct. *)
+  method adjust_overlay_parameters : overlay -> unit
+  (** Called just before copying to allow the input module to adjust
+      parameters of the overlay disk. *)
 end
 (** Encapsulates all [-i], etc input arguments as an object. *)
 
diff --git a/v2v/v2v.ml b/v2v/v2v.ml
index 6bd2e2c..6f98a8c 100644
--- a/v2v/v2v.ml
+++ b/v2v/v2v.ml
@@ -307,6 +307,13 @@ let rec main () =
           if not ((new G.guestfs ())#disk_has_backing_file overlay_file) then
             error (f_"internal error: qemu corrupted the overlay file");
 
+          (* Give the input module a chance to adjust the parameters
+           * of the overlay/backing file.  This allows us to increase
+           * the readahead parameter when copying (see RHBZ#1151033 and
+           * RHBZ#1153589 for the gruesome details).
+           *)
+          input#adjust_overlay_parameters t.target_overlay;
+
           (* It turns out that libguestfs's disk creation code is
            * considerably more flexible and easier to use than
            * qemu-img, so create the disk explicitly using libguestfs
-- 
1.8.3.1