NFSv4.2: Fix up READ_PLUS alignment

Assume that the first segment will be a DATA segment, and place the data
directly into the xdr pages so it doesn't need to be shifted.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs42xdr.c

@@ -47,13 +47,14 @@
 #define decode_deallocate_maxsz		(op_decode_hdr_maxsz)
 #define encode_read_plus_maxsz		(op_encode_hdr_maxsz + \
 					 encode_stateid_maxsz + 3)
-#define NFS42_READ_PLUS_SEGMENT_SIZE	(1 /* data_content4 */ + \
+#define NFS42_READ_PLUS_DATA_SEGMENT_SIZE \
+					(1 /* data_content4 */ + \
 					 2 /* data_info4.di_offset */ + \
-					 2 /* data_info4.di_length */)
+					 1 /* data_info4.di_length */)
 #define decode_read_plus_maxsz		(op_decode_hdr_maxsz + \
 					 1 /* rpr_eof */ + \
 					 1 /* rpr_contents count */ + \
-					 2 * NFS42_READ_PLUS_SEGMENT_SIZE)
+					 NFS42_READ_PLUS_DATA_SEGMENT_SIZE)
 #define encode_seek_maxsz		(op_encode_hdr_maxsz + \
 					 encode_stateid_maxsz + \
 					 2 /* offset */ + \