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