5213 panic in metaslab_init due to space_map_open returning ENXIO
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Bayard Bell <Bayard.Bell@nexenta.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Steven Hartland <steven.hartland@multiplay.co.uk>
Approved by: Dan McDonald <danmcd@omniti.com>