Merge tag 'md-3.11' of git://neil.brown.name/md

Pull md updates from NeilBrown:
 "Mostly fixes, with a few minor features (eg 'last_sync_action' sysfs
  file)

  A couple marked for -stable including one recent bug which causes a
  RAID10 reshape to complete without moving any data :-(

  A couple more bugfixes (at least) to come, but haven't confirmed the
  right solution yet."

* tag 'md-3.11' of git://neil.brown.name/md:
  md/raid10: fix bug which causes all RAID10 reshapes to move no data.
  md/raid5: allow 5-device RAID6 to be reshaped to 4-device.
  md/raid10: fix two bugs affecting RAID10 reshape.
  md: remove doubled description for sync_max, merging it within sync_min/sync_max
  MD: Remember the last sync operation that was performed
  md: fix buglet in RAID5 -> RAID0 conversion.
  md/raid10: check In_sync flag in 'enough()'.
  md/raid10: locking changes for 'enough()'.
  md: replace strict_strto*() with kstrto*()
  md: Wait for md_check_recovery before attempting device removal.
  dm-raid: silence compiler warning on rebuilds_per_group.
  DM RAID: Fix raid_resume not reviving failed devices in all cases
  DM RAID: Break-up untidy function
  DM RAID: Add ability to restore transiently failed devices on resume