NFS: Remove unused FLUSH_SYNC support in nfs_initiate_pgio()

If the FLUSH_SYNC flag is set, nfs_initiate_pgio() will currently
wait for completion, and then return the status of the I/O operation.
What we actually want to report in nfs_pageio_doio() is whether or
not the RPC call was launched successfully, whereas actual I/O
status is intended handled in the reply callbacks.

Since FLUSH_SYNC is never set by any of the callers anyway, let's
just remove that code altogether.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/pagelist.c

@@ -629,7 +629,6 @@ int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 		.workqueue = nfsiod_workqueue,
 		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF | flags,
 	};
-	int ret = 0;
 
 	hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 
@@ -641,18 +640,10 @@ int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 		(unsigned long long)hdr->args.offset);
 
 	task = rpc_run_task(&task_setup_data);
-	if (IS_ERR(task)) {
-		ret = PTR_ERR(task);
-		goto out;
-	}
-	if (how & FLUSH_SYNC) {
-		ret = rpc_wait_for_completion_task(task);
-		if (ret == 0)
-			ret = task->tk_status;
-	}
+	if (IS_ERR(task))
+		return PTR_ERR(task);
 	rpc_put_task(task);
-out:
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);