xen: add blkback support

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Conflicts:

	drivers/xen/Makefile

drivers/xen/Kconfig

@@ -37,6 +37,14 @@ config XEN_BACKEND
 	  Support for backend device drivers that provide I/O services
 	  to other virtual machines.
 
+config XEN_BLKDEV_BACKEND
+	tristate "Block-device backend driver"
+	depends on XEN_BACKEND && BLOCK
+	help
+	  The block-device backend driver allows the kernel to export its
+	  block devices to other guests via a high-performance shared-memory
+	  interface.
+
 config XENFS
 	tristate "Xen filesystem"
 	default y

drivers/xen/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_XEN_BALLOON)	+= xen-balloon.o
 obj-$(CONFIG_XEN_DEV_EVTCHN)	+= xen-evtchn.o
 obj-$(CONFIG_XEN_GNTDEV)	+= xen-gntdev.o
 obj-$(CONFIG_XEN_GRANT_DEV_ALLOC)	+= xen-gntalloc.o
+obj-$(CONFIG_XEN_BLKDEV_BACKEND)	+= blkback/
 obj-$(CONFIG_XENFS)		+= xenfs/
 obj-$(CONFIG_XEN_SYS_HYPERVISOR)	+= sys-hypervisor.o
 obj-$(CONFIG_XEN_PLATFORM_PCI)	+= xen-platform-pci.o

drivers/xen/blkback/Makefile

@@ -0,0 +1,3 @@
+obj-$(CONFIG_XEN_BLKDEV_BACKEND) := blkbk.o
+
+blkbk-y	:= blkback.o xenbus.o interface.o vbd.o