spa->spa_vdev_removal is created in a sync task that is initiated
via dsl_sync_task_nowait(). Since the task may not run before
spa_vdev_remove() returns, we must wait at least 1 txg to ensure
that the removal struct has been created.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#8010