NFSv4.1: Don't loop forever in nfs4_proc_create_session

If a server for some reason keeps sending NFS4ERR_DELAY errors, we can end
up looping forever inside nfs4_proc_create_session, and so the usual
mechanisms for detecting if the nfs_client is dead don't work.

Fix this by ensuring that we loop inside the nfs4_state_manager thread
instead.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/nfs_fs_sb.h

@@ -47,6 +47,7 @@ struct nfs_client {
 
 #ifdef CONFIG_NFS_V4
 	u64			cl_clientid;	/* constant */
+	nfs4_verifier		cl_confirm;	/* Clientid verifier */
 	unsigned long		cl_state;
 
 	spinlock_t		cl_lock;