NFS: Implement SEEK

The SEEK operation is used when an application makes an lseek call with
either the SEEK_HOLE or SEEK_DATA flags set.  I fall back on
nfs_file_llseek() if the server does not have SEEK support.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 0040629..0051b1a 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1239,6 +1239,25 @@
 
 #endif /* CONFIG_NFS_V4_1 */
 
+#ifdef CONFIG_NFS_V4_2
+struct nfs42_seek_args {
+	struct nfs4_sequence_args	seq_args;
+
+	struct nfs_fh			*sa_fh;
+	nfs4_stateid			sa_stateid;
+	u64				sa_offset;
+	u32				sa_what;
+};
+
+struct nfs42_seek_res {
+	struct nfs4_sequence_res	seq_res;
+	unsigned int			status;
+
+	u32	sr_eof;
+	u64	sr_offset;
+};
+#endif
+
 struct nfs_page;
 
 #define NFS_PAGEVEC_SIZE	(8U)