The 5.12 Linux kernel has just been released. Moving the native Linux client to this version exposed various kernel API changes:

1) Support of IDMAPPED mounts. The impact on Lustre is struct user_namespace is passed to all VFS operations.  You can read about this feature at - https://lwn.net/Articles/842423

2) fscrypto API has been reworked.

3) Linux kernel will not build UAPI headers with our CONF_T_* values.

4) rdma_reject() returns an error string to print out.

5) setsockopt uses a new sockptr_t abstract to handle both userland and kernel space at the same tim.