NFS: Create a common argument structure for reads and writes

Reads and writes have very similar arguments.  This patch combines them
together and documents the few fields used only by write.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 73ce8d4..032159c 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1556,7 +1556,8 @@
 	encode_op_hdr(xdr, OP_PUTROOTFH, decode_putrootfh_maxsz, hdr);
 }
 
-static void encode_read(struct xdr_stream *xdr, const struct nfs_readargs *args, struct compound_hdr *hdr)
+static void encode_read(struct xdr_stream *xdr, const struct nfs_pgio_args *args,
+			struct compound_hdr *hdr)
 {
 	__be32 *p;
 
@@ -1701,7 +1702,8 @@
 	encode_nfs4_verifier(xdr, &arg->confirm);
 }
 
-static void encode_write(struct xdr_stream *xdr, const struct nfs_writeargs *args, struct compound_hdr *hdr)
+static void encode_write(struct xdr_stream *xdr, const struct nfs_pgio_args *args,
+			 struct compound_hdr *hdr)
 {
 	__be32 *p;
 
@@ -2451,7 +2453,7 @@
  * Encode a READ request
  */
 static void nfs4_xdr_enc_read(struct rpc_rqst *req, struct xdr_stream *xdr,
-			      struct nfs_readargs *args)
+			      struct nfs_pgio_args *args)
 {
 	struct compound_hdr hdr = {
 		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
@@ -2513,7 +2515,7 @@
  * Encode a WRITE request
  */
 static void nfs4_xdr_enc_write(struct rpc_rqst *req, struct xdr_stream *xdr,
-			       struct nfs_writeargs *args)
+			       struct nfs_pgio_args *args)
 {
 	struct compound_hdr hdr = {
 		.minorversion = nfs4_xdr_minorversion(&args->seq_args),