In current WBC prototype,  all newly directories are created with subtree EX lock returned (WBC). All directories are treated equally with metadata writeback caching. There is no any customization.

It can define various auto caching rule for WBC when create a new directory similar to TBF or PCC.

When a new create directory meets the rule condition, it can try to obtain EX WBC lock from MDS and keep exclusive access on the directory under the protection of the EX lock on the client.

The rule can be combination of uid/gid/projid/fname or jobid.

# lctl wbc $MOUNT $rule
# lctl wbc /mnt/lustre “projid={100}”
# lctl wbc /mnt/lustre “uid={500}&gid={500},fname={*dirmatch*}”
# lctl wbc /mnt/lustre “jobid={dd.*}”