Many fields in data struct @ptlrpc_request can be moved into the data struct @req_capsule:
/** Request message - what client sent */
struct lustre_msg *rq_reqmsg;
/** Reply message - server response */
struct lustre_msg *rq_repmsg;
/** Fields that help to see if request and reply were swabbed or not */
__u32 rq_req_swab_mask;
__u32 rq_rep_swab_mask;
After this data structure reconstructing, req_capsule can be more common usage and it makes pack and unpack sub request for the coming batch metadata processing more easily.
Improvement
Minor
