nvmet: switch loopback target state to connecting when resetting

After commit bb06ec31452f ("nvme: expand nvmf_check_if_ready checks")
resetting of the loopback nvme target failed as we forgot to switch
it's state to NVME_CTRL_CONNECTING before we reconnect the admin
queues. Therefore the checks in nvmf_check_if_ready() choose to go to
the reject_io case and thus we couldn't sent out an identify
controller command to reconnect.

Change the controller state to NVME_CTRL_CONNECTING after tearing down
the old connection and before re-establishing the connection.

Fixes: bb06ec31452f ("nvme: expand nvmf_check_if_ready checks")
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/loop.c

@@ -469,6 +469,12 @@ static void nvme_loop_reset_ctrl_work(struct work_struct *work)
 	nvme_stop_ctrl(&ctrl->ctrl);
 	nvme_loop_shutdown_ctrl(ctrl);
 
+	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_CONNECTING)) {
+		/* state change failure should never happen */
+		WARN_ON_ONCE(1);
+		return;
+	}
+
 	ret = nvme_loop_configure_admin_queue(ctrl);
 	if (ret)
 		goto out_disable;