NFS: Allow the mount option retrans=0

We should allow retrans=0 as just meaning that every timeout is a major
timeout, and that there is no increment in the timeout value.

For instance, this means that we would allow TCP users to specify a
flat timeout value of 60s, by specifying "timeo=600,retrans=0" in their
mount option string.

Siged-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 7ce5e02..74935a1 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -58,6 +58,9 @@
  */
 #define NFS_UNSPEC_PORT		(-1)
 
+#define NFS_UNSPEC_RETRANS	(UINT_MAX)
+#define NFS_UNSPEC_TIMEO	(UINT_MAX)
+
 /*
  * Maximum number of pages that readdir can use for creating
  * a vmapped array of pages.
@@ -156,7 +159,7 @@
 int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *, struct nfs_fattr *);
 void nfs_server_insert_lists(struct nfs_server *);
 void nfs_server_remove_lists(struct nfs_server *);
-void nfs_init_timeout_values(struct rpc_timeout *, int, unsigned int, unsigned int);
+void nfs_init_timeout_values(struct rpc_timeout *to, int proto, int timeo, int retrans);
 int nfs_init_server_rpcclient(struct nfs_server *, const struct rpc_timeout *t,
 		rpc_authflavor_t);
 struct nfs_server *nfs_alloc_server(void);