The F2FS changes this cycle aren't particularly large but include a few enhancements and a number of bug fixes along with some code cleaning. One interesting new addition is adding a mount option to intentionally fragment the on-disk layout of F2FS file-systems.
F2FS' "mode=" mount option has added new options to simulate file-system fragmentation after garbage collection. The "fragment:segment" option will create a new segment in a random position while "fragment:block" will scatter block allocation. New sysfs nodes are added for further tuning the behavior of the "mode=fragment:block" option. Details in this commit .
The developers hope that by making it easier to fragment F2FS partitions it will be easier to understand the behavior and come up with ways to better handle real-world fragmentation and to optimize around it.
F2FS with Linux 5.16 also has direct I/O for multi-partition setups now working. F2FS previously added multi-device support but had missed out on handling of direct I/O for multiple devices.
Those enhancements plus a handful of bug fixes make up the F2FS changes for the Linux 5.16 kernel.