pNFS/files: Handle RDMA connection errors correctly

The RPC/RDMA driver will return -EPROTO and -ENODEV as connection errors
under certain circumstances. Make sure that we handle them correctly and
avoid cycling forever in a LAYOUTGET/LAYOUTRETURN loop.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/filelayout/filelayout.c

@@ -181,6 +181,8 @@ static int filelayout_async_handle_error(struct rpc_task *task,
 	case -EIO:
 	case -ETIMEDOUT:
 	case -EPIPE:
+	case -EPROTO:
+	case -ENODEV:
 		dprintk("%s DS connection error %d\n", __func__,
 			task->tk_status);
 		nfs4_mark_deviceid_unavailable(devid);