This will probably work, but I've seen systems that don't respond if you wait too long to interrupt the process.

One of the problems with hard NFS mounts is that anything you do underneath the mount point will cause a hang if the server is unavailable and sometimes not even a SIGKILL can get rid of the process. One way to handle this might be to fork a child process, which performs the check and quits. As long as the child doesn't exit you know the mount point is down.