xprtrdma: Update comments in rpcrdma_marshal_req()

Update documenting comments to reflect code changes over the past
year.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/rpc_rdma.c

@@ -494,13 +494,10 @@ static void rpcrdma_inline_pullup(struct rpc_rqst *rqst)
  * Marshal a request: the primary job of this routine is to choose
  * the transfer modes. See comments below.
  *
- * Uses multiple RDMA IOVs for a request:
- *  [0] -- RPC RDMA header, which uses memory from the *start* of the
- *         preregistered buffer that already holds the RPC data in
- *         its middle.
- *  [1] -- the RPC header/data, marshaled by RPC and the NFS protocol.
- *  [2] -- optional padding.
- *  [3] -- if padded, header only in [1] and data here.
+ * Prepares up to two IOVs per Call message:
+ *
+ *  [0] -- RPC RDMA header
+ *  [1] -- the RPC header/data
  *
  * Returns zero on success, otherwise a negative errno.
  */
@@ -624,13 +621,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 		__func__, transfertypes[wtype], hdrlen, rpclen,
 		headerp, base, rdmab_lkey(req->rl_rdmabuf));
 
-	/*
-	 * initialize send_iov's - normally only two: rdma chunk header and
-	 * single preregistered RPC header buffer, but if padding is present,
-	 * then use a preregistered (and zeroed) pad buffer between the RPC
-	 * header and any write data. In all non-rdma cases, any following
-	 * data has been copied into the RPC header buffer.
-	 */
 	req->rl_send_iov[0].addr = rdmab_addr(req->rl_rdmabuf);
 	req->rl_send_iov[0].length = hdrlen;
 	req->rl_send_iov[0].lkey = rdmab_lkey(req->rl_rdmabuf);