Pull MD bugfixes from Shaohua Li:

 - fix raid5-ppl flush request handling hang from Artur

 - fix a potential deadlock in raid5/10 reshape from BingJing

 - fix a deadlock for dm-raid from Heinz

 - fix two md-cluster of raid10 from Lidong and Guoqing

 - fix a NULL deference problem in device removal from Neil

 - fix a NULL deference problem in raid1/raid10 in specific condition
   from Yufen

 - other cleanup and fixes

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
  md/raid1: fix NULL pointer dereference
  md: fix a potential deadlock of raid5/raid10 reshape
  md-cluster: choose correct label when clustered layout is not supported
  md: raid5: avoid string overflow warning
  raid5-ppl: fix handling flush requests
  md raid10: fix NULL deference in handle_write_completed()
  md: only allow remove_and_add_spares when no sync_thread running.
  md: document lifetime of internal rdev pointer.
  md: fix md_write_start() deadlock w/o metadata devices
  MD: Free bioset when md_run fails
  raid10: change the size of resync window for clustered raid
  md-multipath: Use seq_putc() in multipath_status()
  md/raid1: Fix trailing semicolon
  md/raid5: simplify uninitialization of shrinker