Fix logs overwriting issue for remote fs (#7889)

* Fix logs overwriting issue for remote fs

* Add test

pytorch_lightning/loggers/tensorboard.py

@@ -267,14 +267,16 @@ class TensorBoardLogger(LightningLoggerBase):
         return self._version
 
     def _get_next_version(self):
-        root_dir = os.path.join(self.save_dir, self.name)
+        root_dir = self.root_dir
 
-        if not self._fs.isdir(root_dir):
+        try:
+            listdir_info = self._fs.listdir(root_dir)
+        except OSError:
             log.warning('Missing logger folder: %s', root_dir)
             return 0
 
         existing_versions = []
-        for listing in self._fs.listdir(root_dir):
+        for listing in listdir_info:
             d = listing["name"]
             bn = os.path.basename(d)
             if self._fs.isdir(d) and bn.startswith("version_"):

tests/loggers/test_tensorboard.py

@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import logging
 import os
 from argparse import Namespace
 from unittest import mock
@@ -340,3 +341,15 @@ def test_tensorboard_with_symlink(log, tmpdir):
     _ = logger.version
 
     log.warning.assert_not_called()
+
+
+def test_tensorboard_missing_folder_warning(tmpdir, caplog):
+    """Verify that the logger throws a warning for invalid directory"""
+
+    name = "fake_dir"
+    logger = TensorBoardLogger(save_dir=tmpdir, name=name)
+
+    with caplog.at_level(logging.WARNING):
+        assert logger.version == 0
+
+    assert 'Missing logger folder:' in caplog.text