nfs: Panic when commit fails

Actually pass the NFS_FILE_SYNC option to the server to avoid a
Panic in nfs_direct_write_complete() when a commit fails.

At the end of an nfs write, if the nfs commit fails, all the writes
will be rescheduled.  They are supposed to be rescheduled as NFS_FILE_SYNC
writes, but the rpc_task structure is not completely intialized and so
the option is not passed.  When the rescheduled writes complete, the
return indicates that they are NFS_UNSTABLE and we try to do another
commit.  This leads to a Panic because the commit data structure pointer
was set to null in the initial (failed) commit attempt.
Signed-off-by: NTerry Loftin <terry.loftin@hp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/direct.c

@@ -457,6 +457,7 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 	};
 	struct rpc_task_setup task_setup_data = {
 		.rpc_client = NFS_CLIENT(inode),
+		.rpc_message = &msg,
 		.callback_ops = &nfs_write_direct_ops,
 		.workqueue = nfsiod_workqueue,
 		.flags = RPC_TASK_ASYNC,