DM-Integrity, which via emulating a block device allows for storing additional integrity information, TRIM/DISCARD is now used to avoid needlessly rewriting of metadata. Additionally, DISCARD is also used to improve hash re-calculation.
Linux 5.13's Device Mapper code also has better scalability of the device hash by making use of rbtree, improved persistent data performance for non-x86 platforms, and removal of DM RAID DISCARD limits for RAID0/RAID10 now that MD has optimized DISCARD handling.
There are also a variety of smaller bug fixes and low-level code improvements.
More details on the DM changes for Linux 5.13 via this merge .