NFSv4.1 wake up all tasks on un-connected DS slot table waitq

The DS has a connection error (invalid deviceid). Drain the fore channel
slot table waitq.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4filelayout.c

@@ -133,6 +133,7 @@ static int filelayout_async_handle_error(struct rpc_task *task,
 	struct nfs_server *mds_server = NFS_SERVER(inode);
 	struct nfs4_deviceid_node *devid = FILELAYOUT_DEVID_NODE(lseg);
 	struct nfs_client *mds_client = mds_server->nfs_client;
+	struct nfs4_slot_table *tbl = &clp->cl_session->fc_slot_table;
 
 	if (task->tk_status >= 0)
 		return 0;
@@ -186,6 +187,7 @@ static int filelayout_async_handle_error(struct rpc_task *task,
 		dprintk("%s DS connection error %d\n", __func__,
 			task->tk_status);
 		filelayout_mark_devid_invalid(devid);
+		rpc_wake_up(&tbl->slot_tbl_waitq);
 		/* fall through */
 	default:
 		dprintk("%s Retry through MDS. Error %d\n", __func__,