storage: add getStatus hook

src/storage/filesystem.js

@@ -10,6 +10,7 @@ exports = module.exports = {
     injectPrivateFields,
 
     getAvailableSize,
+    getStatus,
 
     upload,
     download,
@@ -63,6 +64,21 @@ async function getAvailableSize(config) {
     return dfResult.available;
 }
 
+async function getStatus(config) {
+    assert.strictEqual(typeof config, 'object');
+
+    let hostPath;
+    if (mounts.isManagedProvider(config._provider)) {
+        hostPath = config._managedMountPath;
+    } else if (config._provider === 'mountpoint') {
+        hostPath = config.mountPoint;
+    } else if (config._provider === 'filesystem') {
+        hostPath = config.backupDir;
+    }
+
+    return await mounts.getStatus(config._provider, hostPath); // { state, message }
+}
+
 function hasChownSupportSync(config) {
     switch (config._provider) {
     case mounts.MOUNT_TYPE_NFS: