NFS COPY xdr handle async reply

If server returns async reply, it must include a callback stateid,
wr_callback_id in the write_response4.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs42xdr.c

@@ -389,21 +389,23 @@ static int decode_write_response(struct xdr_stream *xdr,
 				 struct nfs42_write_res *res)
 {
 	__be32 *p;
+	int status, count;
 
-	p = xdr_inline_decode(xdr, 4 + 8 + 4);
+	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(!p))
 		goto out_overflow;
-
-	/*
-	 * We never use asynchronous mode, so warn if a server returns
-	 * a stateid.
-	 */
-	if (unlikely(*p != 0)) {
-		pr_err_once("%s: server has set unrequested "
-				"asynchronous mode\n", __func__);
+	count = be32_to_cpup(p);
+	if (count > 1)
 		return -EREMOTEIO;
+	else if (count == 1) {
+		status = decode_opaque_fixed(xdr, &res->stateid,
+				NFS4_STATEID_SIZE);
+		if (unlikely(status))
+			goto out_overflow;
 	}
-	p++;
+	p = xdr_inline_decode(xdr, 8 + 4);
+	if (unlikely(!p))
+		goto out_overflow;
 	p = xdr_decode_hyper(p, &res->count);
 	res->verifier.committed = be32_to_cpup(p);
 	return decode_verifier(xdr, &res->verifier.verifier);

include/linux/nfs_xdr.h

@@ -1391,6 +1391,7 @@ struct nfs42_copy_args {
 };
 
 struct nfs42_write_res {
+	nfs4_stateid		stateid;
 	u64			count;
 	struct nfs_writeverf	verifier;
 };