all: Add invalid/ignored files to global list, announce to peers (fixes #623)

This lets us determine accurate completion status for remote peers when they
have ignored files.

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4460

cmd/syncthing/main.go

@@ -761,6 +761,17 @@ func syncthingMain(runtimeOptions RuntimeOptions) {
 		// Converts old symlink types to new in the entire database.
 		ldb.ConvertSymlinkTypes()
 	}
+	if cfg.RawCopy().OriginalVersion < 26 {
+		// Adds invalid (ignored) files to global list of files
+		changed := 0
+		for folderID, folderCfg := range folders {
+			changed += ldb.AddInvalidToGlobal([]byte(folderID), protocol.LocalDeviceID[:])
+			for _, deviceCfg := range folderCfg.Devices {
+				changed += ldb.AddInvalidToGlobal([]byte(folderID), deviceCfg.DeviceID[:])
+			}
+		}
+		l.Infof("Database update: Added %d ignored files to the global list", changed)
+	}
 
 	m := model.NewModel(cfg, myID, "syncthing", Version, ldb, protectedFiles)