Comment 4 for bug 1897424

In my env, the block storage sometimes will take long time to connect. So, if i attach the volumes continuously, the latter volume will be waited to the former volume attached completely, and that's why creating bdm timeout in n-api.If adding a delay time in the attach_volume fucntion, the problem will be occured. And we face different types volumes and the timeout can't be predicted in sometime.
I think we should add task state to void this problem.