tests: virtio-9p: add FLUSH operation test

The idea is to send a victim request that will possibly block in the
server and to send a flush request to cancel the victim request.

This patch adds two test to verifiy that:
- the server does not reply to a victim request that was actually
  cancelled
- the server replies to the flush request after replying to the
  victim request if it could not cancel it

9p request cancellation reference:

http://man.cat-v.org/plan_9/5/flush

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
(groug, change the test to only write a single byte to avoid
        any alignment or endianess consideration)

1 files changed, 1 insertions, 0 deletions

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index e88bb50..85a1ed8 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -24,6 +24,7 @@
 #include "coth.h"
 #include "trace.h"
 #include "migration/blocker.h"
+#include "sysemu/qtest.h"
 
 int open_fd_hw;
 int total_open_fd;