Merge tag 'for-5.3/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm into dm-5.3-merge

- Required manual merge of snapshot target's documentation updates due
  to conflicts with shotgun blast of RST changes to DM documentation
  that were _never_ acked by the DM maintainer.

- Add encrypted byte-offset initialization vector (eboiv) to DM crypt.

- Add optional discard features to DM snapshot which allow freeing space
  from a DM device whose free space was exhausted.

- Various small improvements to use struct_size() and kzalloc().

- Fix to check if DM thin metadata is in fail_io mode before attempting
  to update the superblock to set the needs_check flag.  Otherwise the
  DM thin-pool can hang.

- Fix DM bufio shrinker's potential for ABBA recursion deadlock with DM
  thin provisioning on loop usecase.