The attached file is the tcpdump on a client where I ran a "truncate" test ('multiop <file> OTc 1024'). After the MDS_REINT request and reply there is an LDLM_ENQUEUE request and reply for an extent lock. The "verbose" tshark output shows in the header that there are three buffers:
Lm Buflens: 152
Lm Buflens: 112
Lm Buflens: 56
But only the first two 'ptlrpc_body' and 'ldlm_reply' get decoded or even mentioned. I am guessing the thrid buffer is an ost_lvb, but I could well be wrong.