NFSv4.1: Ensure state manager thread dies on last umount

Currently, the state manager may continue to try recovering state forever
even after the last filesystem to reference that nfs_client has umounted.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org

fs/nfs/nfs4state.c

@@ -1607,7 +1607,7 @@ static void nfs4_state_manager(struct nfs_client *clp)
 	int status = 0;
 
 	/* Ensure exclusive access to NFSv4 state */
-	for(;;) {
+	do {
 		if (test_and_clear_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state)) {
 			/* We're going to have to re-establish a clientid */
 			status = nfs4_reclaim_lease(clp);
@@ -1691,7 +1691,7 @@ static void nfs4_state_manager(struct nfs_client *clp)
 			break;
 		if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
 			break;
-	}
+	} while (atomic_read(&clp->cl_count) > 1);
 	return;
 out_error:
 	printk(KERN_WARNING "Error: state manager failed on NFSv4 server %s"