Hi! this is a second revision of the series fixing the most urgent bugs that were introduced by commit 165a5e22fafb "block: Move bdi_unregister() to del_gendisk()" and by 0dba1314d4f8 "scsi, block: fix duplicate bdi name registration crashes". In fact before these commits we had a different set of problems in the code but they were less visible :). Changes since v1: * Added Acked-by and Tested-by tags * Changed usage_cnt increment to reinitialize as requested by Tejun and James Honza
