[PATCH] fix userspace compiles with nbd.h

From: Paul Clements <Paul.Clements@SteelEye.com>

A previous "cleanup" on the nbd.h header file broke userspace compiles.
I've added an #ifdef __KERNEL__ so that userspace doesn't need to worry
about the nbd_device structure, which is only used in-kernel. The patch
allows me to compile my nbd tools with the 2.6 nbd.h.

include/linux/nbd.h

@@ -35,6 +35,9 @@ enum {
 /* Define PARANOIA to include extra sanity checking code in here & driver */
 #define PARANOIA
 
+/* userspace doesn't need the nbd_device structure */
+#ifdef __KERNEL__
+
 struct nbd_device {
 	int flags;
 	int harderror;		/* Code of hard error			*/
@@ -53,6 +56,8 @@ struct nbd_device {
 	u64 bytesize;
 };
 
+#endif
+
 /* This now IS in some kind of include file...	*/
 
 /* These are send over network in request/reply magic field */