Pull MD fixes from Shaohua Li:
"A few fixes for MD. Mainly fix a problem introduced in 4.13, which we
retry bio for some code paths but not all in some situations"
* tag 'md/4.14-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
md/raid5: cap worker count
dm-raid: fix a race condition in request handling
md: fix a race condition for flush request handling
md: separate request handling