commit 7801c3a7fd7042fd2f9435af4b9a6d2094073174
author Eric Blake <eblake@redhat.com> Fri Jan 11 13:47:14 2019 -0600
committer Eric Blake <eblake@redhat.com> Mon Jan 14 10:09:46 2019 -0600
tree e5a928e2006700b12b5b5b67c3073931972801d3
parent 2d2fd67428f0cfbffea16969d2635af3e2d78d3d

nbd: Forbid nbd-server-stop when server is not running

Since we already forbid other nbd-server commands when not
in the right state, it is unlikely that any caller was relying
on a second stop to behave as a silent no-op.  Update iotest
223 to show the improved behavior.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

blockdev-nbd.c

diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 1d170c8..ca58491 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -214,6 +214,11 @@
 
 void qmp_nbd_server_stop(Error **errp)
 {
+    if (!nbd_server) {
+        error_setg(errp, "NBD server not running");
+        return;
+    }
+
     nbd_export_close_all();
 
     nbd_server_free(nbd_server);