fix: be more tolerant to error handling in Mounts API

Fixes #8202

If some mountpoint can't be queried successfully for 'diskfree'
information, don't treat that as an error, and report zero values for
disk usage/size instead.

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

cmd/talosctl/cmd/talos/mounts.go

@@ -31,7 +31,7 @@ var mountsCmd = &cobra.Command{
 			resp, err := c.Mounts(ctx, grpc.Peer(&remotePeer))
 			if err != nil {
 				if resp == nil {
-					return fmt.Errorf("error getting interfaces: %s", err)
+					return fmt.Errorf("error getting mount information: %s", err)
 				}
 
 				cli.Warning("%s", err)

internal/app/machined/internal/server/v1alpha1/v1alpha1_server.go

@@ -1075,26 +1075,20 @@ func (s *Server) Mounts(ctx context.Context, in *emptypb.Empty) (reply *machine.
 		filesystem := fields[0]
 		mountpoint := fields[1]
 
-		f, err := os.Stat(mountpoint)
-		if err != nil {
-			multiErr = multierror.Append(multiErr, err)
+		var (
+			totalSize  uint64
+			totalAvail uint64
+		)
 
-			continue
+		if statInfo, err := os.Stat(mountpoint); err == nil && statInfo.Mode().IsDir() {
+			if err := unix.Statfs(mountpoint, &stat); err != nil {
+				multiErr = multierror.Append(multiErr, err)
+			} else {
+				totalSize = uint64(stat.Bsize) * stat.Blocks
+				totalAvail = uint64(stat.Bsize) * stat.Bavail
+			}
 		}
 
-		if mode := f.Mode(); !mode.IsDir() {
-			continue
-		}
-
-		if err := unix.Statfs(mountpoint, &stat); err != nil {
-			multiErr = multierror.Append(multiErr, err)
-
-			continue
-		}
-
-		totalSize := uint64(stat.Bsize) * stat.Blocks
-		totalAvail := uint64(stat.Bsize) * stat.Bavail
-
 		stat := &machine.MountStat{
 			Filesystem: filesystem,
 			Size:       totalSize,