From 1880daf59d1b1cab9d01a3ac57ed0390c305e64e Mon Sep 17 00:00:00 2001
From: Hector Sanjuan <code@hector.link>
Date: Tue, 12 May 2020 21:17:25 +0200
Subject: [PATCH] Fix #1120: Do not let the size metric underflow uint.

---
 informer/disk/disk.go | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/informer/disk/disk.go b/informer/disk/disk.go
index b9b9f31d..6c4f55e1 100644
--- a/informer/disk/disk.go
+++ b/informer/disk/disk.go
@@ -98,7 +98,13 @@ func (disk *Informer) GetMetric(ctx context.Context) *api.Metric {
 	} else {
 		switch disk.config.MetricType {
 		case MetricFreeSpace:
-			metric = repoStat.StorageMax - repoStat.RepoSize
+			size := repoStat.RepoSize
+			total := repoStat.StorageMax
+			if size < total {
+				metric = total - size
+			} else { // Make sure we don't underflow
+				metric = 0
+			}
 		case MetricRepoSize:
 			metric = repoStat.RepoSize
 		}