--- /dev/null
+lustre/ptlrpc/layout.c establishes a mapping between the symbols
+(starting with RMF_) for message format structures and the actual
+structure definitions they represent. There are three entries in this
+mapping that do not appear in any message format. They are:
+ RMF_OST_ID => ost_id
+ RMF_STRING => string
+ RMF_U32 => u32
+There are also three duplicates:
+ RMF_CAPA1 => capa and
+ RMF_CAPA2 => capa
+ RMF_FIEMAP_KEY => fiemap and
+ RMF_FIEMAP_VAL => fiemap
+ RMF_NIOBUF_REMOTE => niobuf_remote and
+ RMF_RCS => niobuf_remote
+
+The mesage format symbols RMF_MGS_CONFIG_BODY and RMF_MGS_CONFIG_RES
+have the names, respecitvely, "mgs_config_read request" and
+"mgs_config_read reply" with two words (or a missing
+underscore). Similarly, RMF_U32 has the name "generic u32".
+
+Many of the message format symbols have a name that is the same as the
+symbol but in lower case and with out the leading "RMF_". On the other
+hand many of the symbols do not follow this pattern. Each declaration
+also has a field for the size to be allocated for the structure, and
+most use the "sizeof(struct the_struct)" construction to identify the
+size needed. That construct then gives a notion of what actual
+structure definition is going to give meaning to the bytes in that
+structure. The sizeof column presents that 'struct' name or a hint
+about the size of the message. A value of "-1" means, "the size is not
+going to be well defined in advance." Thus additional hits will need
+ot be included in the rest of the message.
+
+message format symbol name sizeof
+--------------------- ---------------- ------------------
+RMF_ACL acl LUSTRE_POSIX_ACL_MAX_SIZE
+RMF_CAPA1 capa lustre_capa
+RMF_CAPA2 capa lustre_capa
+RMF_CLOSE_DATA data_version close_data
+RMF_CLUUID cluuid obd_uuid
+RMF_CONN conn lustre_handle
+RMF_CONNECT_DATA cdata obd_connect_data
+RMF_DLM_GL_DESC dlm_gl_desc ldlm_gl_desc
+RMF_DLM_LVB dlm_lvb -1
+RMF_DLM_REP dlm_rep ldlm_reply
+RMF_DLM_REQ dlm_req ldlm_request
+RMF_EADATA eadata -1
+RMF_EAVALS eavals -1
+RMF_EAVALS_LENS eavals_lens __u32
+RMF_FID fid lu_fid
+RMF_FIEMAP_KEY fiemap ll_fiemap_info_key
+RMF_FIEMAP_VAL fiemap -1
+RMF_FLD_MDFLD fld_query_mdfld lu_seq_range
+RMF_FLD_OPC fld_query_opc __u32
+RMF_GENERIC_DATA generic_data -1
+RMF_GETINFO_KEY getinfo_key -1
+RMF_GETINFO_VAL getinfo_val -1
+RMF_GETINFO_VALLEN getinfo_vallen __u32
+RMF_HSM_STATE_SET hsm_state_set hsm_state_set
+RMF_HSM_USER_STATE hsm_user_state hsm_user_state
+RMF_IDX_INFO idx_info idx_info
+RMF_LAYOUT_INTENT layout_intent layout_intent
+RMF_LDLM_INTENT ldlm_intent ldlm_intent
+RMF_LFSCK_REPLY lfsck_reply lfsck_reply
+RMF_LFSCK_REQUEST lfsck_request lfsck_request
+RMF_LLOGD_BODY llogd_body llogd_body
+RMF_LLOGD_CONN_BODY llogd_conn_body llogd_conn_body
+RMF_LLOG_LOG_HDR llog_log_hdr llog_log_hdr
+RMF_LOGCOOKIES logcookies llog_cookie
+RMF_MDS_HSM_ARCHIVE hsm_archive __u32
+RMF_MDS_HSM_CURRENT_ACTION hsm_current_action hsm_current_action
+RMF_MDS_HSM_PROGRESS hsm_progress hsm_progress_kernel
+RMF_MDS_HSM_REQUEST hsm_request hsm_request
+RMF_MDS_HSM_USER_ITEM hsm_user_item hsm_user_item
+RMF_MDT_BODY mdt_body mdt_body
+RMF_MDT_EPOCH mdt_ioepoch mdt_ioepoch
+RMF_MDT_MD mdt_md MIN_MD_SIZE
+RMF_MGS_CONFIG_BODY mgs_config_read request mgs_config_body
+RMF_MGS_CONFIG_RES mgs_config_read reply mgs_config_res
+RMF_MGS_SEND_PARAM mgs_send_param mgs_send_param
+RMF_MGS_TARGET_INFO mgs_target_info mgs_target_info
+RMF_NAME name -1
+RMF_NIOBUF_REMOTE niobuf_remote niobuf_remote
+RMF_OBD_ID obd_id __u64
+RMF_OBD_IOOBJ obd_ioobj obd_ioobj
+RMF_OBD_QUOTACTL obd_quotactl obd_quotactl
+RMF_OBD_STATFS obd_statfs obd_statfs
+RMF_OST_BODY ost_body ost_body
+RMF_OST_ID ost_id ost_id
+RMF_OUT_UPDATE object_update -1
+RMF_OUT_UPDATE_REPLY object_update_reply -1
+RMF_PTLRPC_BODY ptlrpc_body (aka ptlrpc_body_v3) ptlrpc_body
+RMF_QUOTA_BODY quota_body quota_body
+RMF_RCS niobuf_remote __u32
+RMF_REC_REINT rec_reint mdt_rec_reint
+RMF_SEQ_OPC seq_query_opc __u32
+RMF_SEQ_RANGE seq_query_range lu_seq_range
+RMF_SETINFO_KEY setinfo_key -1
+RMF_SETINFO_VAL setinfo_val -1
+RMF_STRING string -1
+RMF_SWAP_LAYOUTS swap_layouts mdc_swap_layouts
+RMF_SYMTGT symtgt -1
+RMF_TGTUUID tgtuuid obd_uuid
+RMF_U32 generic u32 u32 __u32
+