Comment 4 for bug 1891151

For 5.8 this is a simple backport with one conflict caused by function md_make_request() renamed to md_submit_bio(). Then it can be easily cherry picked to 5.4 but will need a change to use generic_{start,end}_io_acct() instead of disk_{start,end}_io_acct(). I can send you the backported patches if you wish.