nfs: increase size of EXCHANGE_ID name string buffer

commit 764ad8ba upstream.

The current buffer is much too small if you have a relatively long
hostname. Bring it up to the size of the one that SETCLIENTID has.
Reported-by: Michael Skralivetsky <michael.skralivetsky@primarydata.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>

include/linux/nfs_xdr.h

@@ -1061,7 +1061,7 @@ struct nfstime4 {
 };
 
 #ifdef CONFIG_NFS_V4_1
-#define NFS4_EXCHANGE_ID_LEN	(48)
+#define NFS4_EXCHANGE_ID_LEN	(127)
 struct nfs41_exchange_id_args {
 	struct nfs_client		*client;
 	nfs4_verifier			*verifier;