Merge branch 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md into block-5.9

Pull MD fixes from Song.

* 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md:
  md-cluster: Fix potential error pointer dereference in resize_bitmaps()
  md: get sysfs entry after redundancy attr group create