From 592819524390bc354d16940107e4c22ca41e48b9 Mon Sep 17 00:00:00 2001
From: Olaf Hering <olaf@aepfle.de>
Date: Mon, 3 Sep 2012 19:50:44 +0200
Subject: force virtio_blk in old guest kernel

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 fish/options.c         |  7 +++++--
 src/guestfs-internal.h |  1 +
 src/handle.c           | 16 ++++++++++++++++
 src/inspect-fs-unix.c  |  4 ++--
 src/launch-direct.c    |  2 ++
 5 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/fish/options.c b/fish/options.c
index 75d61ad..b0bcd09 100644
--- a/fish/options.c
+++ b/fish/options.c
@@ -80,7 +80,10 @@ add_drives (struct drv *drv, char next_drive)
 {
   int r;
   struct guestfs_add_drive_opts_argv ad_optargs;
-
+  int use_virtio_blk = 0;
+#ifdef GUESTFS_QEMU_NO_VIRTIO_BLK
+  use_virtio_blk = 1;
+#endif
   if (next_drive > 'z') {
     fprintf (stderr,
              _("%s: too many drives added on the command line\n"),
@@ -94,7 +97,7 @@ add_drives (struct drv *drv, char next_drive)
     free (drv->device);
     drv->device = NULL;
 
-    if (asprintf (&drv->device, "/dev/sd%c", next_drive) == -1) {
+    if (asprintf (&drv->device, "/dev/%s%c", use_virtio_blk ? "vd" : "sd", next_drive) == -1) {
       perror ("asprintf");
       exit (EXIT_FAILURE);
     }
diff --git a/src/guestfs-internal.h b/src/guestfs-internal.h
index 5356920..2a9f9fe 100644
--- a/src/guestfs-internal.h
+++ b/src/guestfs-internal.h
@@ -472,6 +472,7 @@ struct guestfs_h
   unsigned int nr_requested_credentials;
   virConnectCredentialPtr requested_credentials;
 #endif
+  int use_virtio_blk;
 };
 
 /* Per-filesystem data stored for inspect_os. */
diff --git a/src/handle.c b/src/handle.c
index fa96d95..e1732d7 100644
--- a/src/handle.c
+++ b/src/handle.c
@@ -237,6 +237,22 @@ parse_environment (guestfs_h *g,
     }
   }
 
+/*
+ * Currently virtio_scsi is forced if qemu in the host supports this
+ * feature. This test does however not take the capabilities of the started
+ * guest into account. As a result no disks will be found if the guest
+ * kernel is older than 3.4.
+ */
+#ifdef GUESTFS_QEMU_NO_VIRTIO_BLK
+  static const char env_string[] = "GUESTFS_QEMU_NO_VIRTIO_BLK";
+  str = getenv(env_string);
+  g->use_virtio_blk = str == NULL;
+  if (str)
+    debug (g, "SuSE: %s in environment, preserving virtio-scsi setting.", env_string);
+  else
+    debug (g, "SuSE: %s not in environment, preventing virtio-scsi usage in old guest kernel.", env_string);
+#endif
+
   return 0;
 }
 
diff --git a/src/inspect-fs-unix.c b/src/inspect-fs-unix.c
index 8e0f135..83d23c7 100644
--- a/src/inspect-fs-unix.c
+++ b/src/inspect-fs-unix.c
@@ -1407,7 +1407,7 @@ resolve_fstab_device_diskbyid (guestfs_h *g, const char *part,
     return 0;
 
   /* Make the partition name and check it exists. */
-  device = safe_asprintf (g, "/dev/sda%s", part);
+  device = safe_asprintf (g, "/dev/%sa%s", g->use_virtio_blk ? "vd" : "sd", part);
   if (!is_partition (g, device)) {
     free (device);
     return 0;
@@ -1500,7 +1500,7 @@ resolve_fstab_device (guestfs_h *g, const char *spec, Hash_table *md_map)
     if (disk_i != -1 && disk_i <= 26 &&
         slice_i > 0 && slice_i <= 1 /* > 4 .. see comment above */ &&
         part_i >= 0 && part_i < 26) {
-      device = safe_asprintf (g, "/dev/sd%c%d", disk_i + 'a', part_i + 5);
+      device = safe_asprintf (g, "/dev/%s%c%d", g->use_virtio_blk ? "vd" : "sd", disk_i + 'a', part_i + 5);
     }
   }
   else if ((part = match1 (g, spec, re_diskbyid)) != NULL) {
diff --git a/src/launch-direct.c b/src/launch-direct.c
index 070c649..a4c94e8 100644
--- a/src/launch-direct.c
+++ b/src/launch-direct.c
@@ -1068,6 +1068,8 @@ qemu_supports_virtio_scsi (guestfs_h *g, struct backend_direct_data *data)
         data->virtio_scsi = 3;
     }
   }
+ if (g->use_virtio_blk)
+     data->virtio_scsi = 2;
 
   return data->virtio_scsi == 1;
 }