blktap2: add blktap2 device class and device controller

blktap2 devices must be handled differently than blktap2
devices. blktap2 devices require a sysfs write to close the underlying
device, as well as extra sysfs writes when the domU is
paused/unpaused. The differences between blktap1 and blktap2 are great
enough to warrant the creation of a new device class, 'tap2', and
device controller for blktap2 devices.

  * add a new device controller (Blktap2Controller) and device class
    (tap2) for blktap2 devices
  * move blktap2 specific code from DevController to Blktap2Controller
  * if possible, check xenstore to determine block device class
  * use vmpath (/vm/<uuid>/) when releasing devices
  * modify linux hotplug cleanup script to handle blktap2 device
    removal

Signed-off-by: Ryan O'Connor <rjo@cs.ubc.ca>

1 files changed, 7 insertions, 0 deletions

diff --git a/tools/hotplug/Linux/xen-hotplug-cleanup b/tools/hotplug/Linux/xen-hotplug-cleanup
index 0cb86d27ec..f4d016232d 100644
--- a/tools/hotplug/Linux/xen-hotplug-cleanup
+++ b/tools/hotplug/Linux/xen-hotplug-cleanup
@@ -18,6 +18,13 @@ vm=$(xenstore_read_default "/local/domain/${path_array[2]}/vm" "")
 # construct /vm/UUID/device/DEVCLASS/DEVID
 if [ "$vm" != "" ]; then
   vm_dev="$vm/device/${path_array[1]}/${path_array[3]}"
+
+  # if the vm path does not exist and the device class is 'vbd' then we may have
+  # a tap2 device
+  if [ ! $(xenstore-read "vm_dev" 2>/dev/null) ] \
+       && [ "${path_array[1]}" = "vbd" ]; then
+    vm_dev="$vm/device/tap2/${path_array[3]}"
+  fi
 else
   vm_dev=
 fi