NFSv4: Add tracing for COMPOUND errors

When the server returns a different operation than we expected, then
trace that.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs4trace.h

@@ -666,6 +666,41 @@ TRACE_EVENT(nfs4_state_mgr_failed,
 		)
 )
 
+TRACE_EVENT(nfs4_xdr_bad_operation,
+		TP_PROTO(
+			const struct xdr_stream *xdr,
+			u32 op,
+			u32 expected
+		),
+
+		TP_ARGS(xdr, op, expected),
+
+		TP_STRUCT__entry(
+			__field(unsigned int, task_id)
+			__field(unsigned int, client_id)
+			__field(u32, xid)
+			__field(u32, op)
+			__field(u32, expected)
+		),
+
+		TP_fast_assign(
+			const struct rpc_rqst *rqstp = xdr->rqst;
+			const struct rpc_task *task = rqstp->rq_task;
+
+			__entry->task_id = task->tk_pid;
+			__entry->client_id = task->tk_client->cl_clid;
+			__entry->xid = be32_to_cpu(rqstp->rq_xid);
+			__entry->op = op;
+			__entry->expected = expected;
+		),
+
+		TP_printk(
+			"task:%u@%d xid=0x%08x operation=%u, expected=%u",
+			__entry->task_id, __entry->client_id, __entry->xid,
+			__entry->op, __entry->expected
+		)
+);
+
 TRACE_EVENT(nfs4_xdr_status,
 		TP_PROTO(
 			const struct xdr_stream *xdr,

fs/nfs/nfs4xdr.c

@@ -3210,9 +3210,7 @@ static bool __decode_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected,
 	*nfs_retval = nfs4_stat_to_errno(nfserr);
 	return true;
 out_bad_operation:
-	dprintk("nfs: Server returned operation"
-		" %d but we issued a request for %d\n",
-			opnum, expected);
+	trace_nfs4_xdr_bad_operation(xdr, opnum, expected);
 	*nfs_retval = -EREMOTEIO;
 	return false;
 out_overflow: