New code for 5.13:
- Various minor fixes in online scrub.
- Prevent metadata files from being automatically inactivated.
- Validate btree heights by the computed per-btree limits.
- Don't warn about remounting with deprecated mount options.
- Initialize attr forks at create time if we suspect we're going to need
  to store them.
- Reduce memory reallocation workouts in the logging code.
- Fix some theoretical math calculation errors in logged buffers that
  span multiple discontig memory ranges but contiguous ondisk regions.
- Speedups in dirty buffer bitmap handling.
- Make type verifier functions more inline-happy to reduce overhead.
- Reduce debug overhead in directory checking code.
- Many many typo fixes.
- Begin to handle the permanent loss of the very end of a filesystem.
- Fold struct xfs_icdinode into xfs_inode.
- Deprecate the long defunct BMV_IF_NO_DMAPI_READ from the bmapx ioctl.
- Remove a broken directory block format check from online scrub.
- Fix a bug where we could produce an unnecessarily tall data fork btree
  when creating an attr fork.
- Fix scrub and readonly remounts racing.
- Fix a writeback ioend log deadlock problem by dropping the behavior
  where we could preallocate a setfilesize transaction.
- Fix some bugs in the new extent count checking code.
- Fix some bugs in the attr fork preallocation code.