fanotify: userspace interface for permission responses

fanotify groups need to respond to events which include permissions types.
To do so groups will send a response using write() on the fanotify_fd they
have open.

Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 02f8067..f0949a5 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -75,6 +75,11 @@
 	__s64 pid;
 } __attribute__ ((packed));
 
+struct fanotify_response {
+	__s32 fd;
+	__u32 response;
+} __attribute__ ((packed));
+
 /* Legit userspace responses to a _PERM event */
 #define FAN_ALLOW	0x01
 #define FAN_DENY	0x02