On the feature front for Linux 5.12, this mature file-system has seen work to speed up freezing when read-only workloads are still running, refactoring to the logging code, faster fsync and garbage collection scans, and continued work towards being able to support shrinking XFS file-systems.
Particularly on the garbage collection front, the XFS code has seen a lot of improvements. -- including making more of the code multi-threaded. Background file garbage collection might also be ready for the Linux 5.13 kernel or shortly after that point otherwise.
XFS is also enjoying a number of bug fixes and other code improvements as outlined via this pull request . Darrick also sent in the IOmap code updates for Linux 5.12 that add the ability for XFS to try unaligned direct I/O overwrites without taking locks.
It's great seeing the continued XFS features and improvements in addition to the recent surge of feature/performance work around the likes of Btrfs and the out-of-tree OpenZFS as well. Plus perhaps this year we still might see the likes of Bcachefs merged to mainline as another promising Linux storage effort.