NFSD: Update the NFSv2 WRITE argument decoder to use struct xdr_stream

int

nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p)

{

	struct xdr_stream *xdr = &rqstp->rq_arg_stream;

	struct nfsd_writeargs *args = rqstp->rq_argp;

	unsigned int len, hdr, dlen;

	struct kvec *head = rqstp->rq_arg.head;

	struct kvec *tail = rqstp->rq_arg.tail;

	u32 beginoffset, totalcount;

	size_t remaining;

	p = decode_fh(p, &args->fh);

	if (!p)

	if (!svcxdr_decode_fhandle(xdr, &args->fh))

		return 0;

	p++;				/* beginoffset */

	args->offset = ntohl(*p++);	/* offset */

	p++;				/* totalcount */

	len = args->len = ntohl(*p++);

	/*

	 * The protocol specifies a maximum of 8192 bytes.

	 */

	if (len > NFSSVC_MAXBLKSIZE_V2)

	/* beginoffset is ignored */

	if (xdr_stream_decode_u32(xdr, &beginoffset) < 0)

		return 0;

	/*

	 * Check to make sure that we got the right number of

	 * bytes.

	 */

	hdr = (void*)p - head->iov_base;

	if (hdr > head->iov_len)

	if (xdr_stream_decode_u32(xdr, &args->offset) < 0)

		return 0;

	/* totalcount is ignored */

	if (xdr_stream_decode_u32(xdr, &totalcount) < 0)

		return 0;

	dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;

	/*

	 * Round the length of the data which was specified up to

	 * the next multiple of XDR units and then compare that

	 * against the length which was actually received.

	 * Note that when RPCSEC/GSS (for example) is used, the

	 * data buffer can be padded so dlen might be larger

	 * than required.  It must never be smaller.

	 */

	if (dlen < XDR_QUADLEN(len)*4)

	/* opaque data */

	if (xdr_stream_decode_u32(xdr, &args->len) < 0)

		return 0;

	if (args->len > NFSSVC_MAXBLKSIZE_V2)

		return 0;

	remaining = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len;

	remaining -= xdr_stream_pos(xdr);

	if (remaining < xdr_align_size(args->len))

		return 0;

	args->first.iov_base = xdr->p;

	args->first.iov_len = head->iov_len - xdr_stream_pos(xdr);

	args->first.iov_base = (void *)p;

	args->first.iov_len = head->iov_len - hdr;

	return 1;

}