Because the unmap code just after the schdule() returned may take
a long time and if the kthread_stop() is fired just when in this
routine, the module removal maybe stuck too.
Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>