Silence merge splice error when forcing

Silence another error warning and assertion that's assuming that the
result of the errors is going to be persistent.  When we're forcing an
unmount we've severed storage and networking.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/msg.h

@@ -35,6 +35,12 @@ do {									\
 	}								\
 } while (0)								\
 
+#define scoutfs_bug_on_err(sb, err, fmt, args...) \
+do { \
+	__typeof__(err) _err = (err); \
+	scoutfs_bug_on(sb, _err < 0 && _err != -ENOLINK, fmt, ##args); \
+} while (0)
+
 /*
  * Each message is only generated once per volume.  Remounting resets
  * the messages.

kmod/src/server.c

@@ -2518,10 +2518,9 @@ out:
 		}
 	}
 
-	if (ret < 0)
-		scoutfs_err(sb, "server error %d splicing log merge completion: %s", ret, err_str);
-
-	BUG_ON(ret); /* inconsistent */
+	/* inconsistent */
+	scoutfs_bug_on_err(sb, ret,
+			   "server error %d splicing log merge completion: %s", ret, err_str);
 
 	return ret ?: einprogress;
 }