nfs: allow to specify cred in nfs_initiate_pgio

so that flexfile layout client can pass in DS credential instead of
using user cred, which will be done in the next patch.

Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 98dee83..e9305e9 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -250,9 +250,9 @@
 void nfs_pgio_header_free(struct nfs_pgio_header *);
 void nfs_pgio_data_destroy(struct nfs_pgio_header *);
 int nfs_generic_pgio(struct nfs_pageio_descriptor *, struct nfs_pgio_header *);
-int nfs_initiate_pgio(struct rpc_clnt *, struct nfs_pgio_header *,
-		      const struct nfs_rpc_ops *,
-		      const struct rpc_call_ops *, int, int);
+int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
+		      struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
+		      const struct rpc_call_ops *call_ops, int how, int flags);
 void nfs_free_request(struct nfs_page *req);
 
 static inline void nfs_iocounter_init(struct nfs_io_counter *c)