block/vpc: fix virtual size for images created with disk2vhd

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/block/vpc.c b/block/vpc.c
index 627d11c..577cc459 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -211,6 +211,15 @@
     bs->total_sectors = (int64_t)
         be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
 
+    /* images created with disk2vhd report a far higher virtual size
+     * than expected with the cyls * heads * sectors_per_cyl formula.
+     * use the footer->size instead if the image was created with
+     * disk2vhd.
+     */
+    if (!strncmp(footer->creator_app, "d2v", 4)) {
+        bs->total_sectors = be64_to_cpu(footer->size) / BDRV_SECTOR_SIZE;
+    }
+
     /* Allow a maximum disk size of approximately 2 TB */
     if (bs->total_sectors >= 65535LL * 255 * 255) {
         ret = -EFBIG;