baremetal-builders: detect percent_filled for the correct partition

flake.lock

@@ -64,13 +64,13 @@
         "treefmt-nix": "treefmt-nix"
       },
       "locked": {
-        "lastModified": 1722190692,
-        "narHash": "sha256-meyufek9SElo8iAHMs5ii55Eg7kdJxjMxAkYDvnDRpo=",
-        "ref": "refs/heads/non-flakes",
-        "rev": "8f5ad30cb7df5afbc4df1370a79bf3825c60f8b1",
-        "revCount": 291,
+        "lastModified": 1722339507,
+        "narHash": "sha256-CdkQx6l0CuPtU9tMw3u73PAMhj+8YUAlTUVyrTCZas8=",
+        "ref": "15963fa0e687cb39660aadf147402c955d671029",
+        "rev": "15963fa0e687cb39660aadf147402c955d671029",
+        "revCount": 292,
         "type": "git",
-        "url": "https://git.lix.systems/lix-project/buildbot-nix.git"
+        "url": "file:///home/yuka/proj/buildbot-nix"
       },
       "original": {
         "ref": "refs/heads/non-flakes",

services/baremetal-builder/default.nix

@@ -153,7 +153,7 @@ in
       description = "Nix Garbage Collector";
       script = ''
         while : ; do
-          percent_filled=$(($(stat -f --format="100-(100*%a/%b)" /)))
+          percent_filled=$(($(stat -f --format="100-(100*%a/%b)" /mnt)))
           if [ "$percent_filled" -gt "85" ]; then
             ${config.nix.package.out}/bin/nix-store --gc --max-freed 100G --store /mnt
           else