ocfs2: optimize error handling in dlm_request_join

Currently error handling in dlm_request_join is a little obscure, so
optimize it to promote readability.

If packet.code is invalid, reset it to JOIN_DISALLOW to keep it
meaningful.  It only influences the log printing.
Signed-off-by: Norton.Zhu <norton.zhu@huawei.com>
Cc: Srinivas Eeda <srinivas.eeda@oracle.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/dlm/dlmdomain.c

@@ -1465,10 +1465,13 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
 	if (status == -ENOPROTOOPT) {
 		status = 0;
 		*response = JOIN_OK_NO_MAP;
-	} else if (packet.code == JOIN_DISALLOW ||
-		   packet.code == JOIN_OK_NO_MAP) {
+	} else {
 		*response = packet.code;
-	} else if (packet.code == JOIN_PROTOCOL_MISMATCH) {
+		switch (packet.code) {
+		case JOIN_DISALLOW:
+		case JOIN_OK_NO_MAP:
+			break;
+		case JOIN_PROTOCOL_MISMATCH:
 			mlog(ML_NOTICE,
 			     "This node requested DLM locking protocol %u.%u and "
 			     "filesystem locking protocol %u.%u.  At least one of "
@@ -1480,9 +1483,8 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
 			     dlm->fs_locking_proto.pv_minor,
 			     node);
 			status = -EPROTO;
-		*response = packet.code;
-	} else if (packet.code == JOIN_OK) {
-		*response = packet.code;
+			break;
+		case JOIN_OK:
 			/* Use the same locking protocol as the remote node */
 			dlm->dlm_locking_proto.pv_minor = packet.dlm_minor;
 			dlm->fs_locking_proto.pv_minor = packet.fs_minor;
@@ -1494,10 +1496,15 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
 			     dlm->dlm_locking_proto.pv_minor,
 			     dlm->fs_locking_proto.pv_major,
 			     dlm->fs_locking_proto.pv_minor);
-	} else {
+			break;
+		default:
 			status = -EINVAL;
 			mlog(ML_ERROR, "invalid response %d from node %u\n",
 			     packet.code, node);
+			/* Reset response to JOIN_DISALLOW */
+			*response = JOIN_DISALLOW;
+			break;
+		}
 	}
 
 	mlog(0, "status %d, node %d response is %d\n", status, node,