tests/qtest/virtio-scsi: force QEMU restart for iothread-virtio-error

The qos framework reuses QEMU instances between tests with identical
command lines, issuing system_reset instead of restarting. After
iothread-attach-node, system_reset can deadlock in bdrv_graph_wrlock
during drain on slow/contended CI runners.

Force a fresh QEMU instance by adding seg_max_adjust=off to make
the command line differ.

Signed-off-by: Jason Truong <jason.truong@windriver.com>

Author: hungmtruong

tests/qtest/virtio-scsi-test.c

@@ -411,7 +411,12 @@ static void register_virtio_scsi_test(void)
 
     opts.before = virtio_scsi_setup_iothread;
     opts.edge = (QOSGraphEdgeOptions) {
-        .extra_device_opts = "iothread=thread0",
+        /*
+         * Use seg_max_adjust=off to force a fresh QEMU instance.
+         * Without this, the qos framework reuses the previous instance
+         * with system_reset, which can deadlock in bdrv_graph_wrlock.
+         */
+        .extra_device_opts = "iothread=thread0,seg_max_adjust=off",
     };
     qos_add_test("iothread-virtio-error", "virtio-scsi-pci",
                  test_iothread_virtio_error, &opts);