Man page 9 : xdr_init_encode

xdr_init_encode - Initialize a struct xdr_stream for sending data.

void xdr_init_encode(struct xdr_stream *  xdr , struct xdr_buf *  buf , __be32 *  p );

xdr
    pointer to xdr_stream struct

buf
    pointer to XDR buffer in which to encode data

p
    current pointer inside XDR buffer

at the moment the RPC client only passes the length of our scratch buffer in the xdr_bufAqs header kvec. Previously this meant we needed to call xdr_adjust_iovec after encoding the data. With the new scheme, the xdr_stream manages the details of the buffer length, and takes care of adjusting the kvec length for us.