"File name too long" error for file locks
Yes, you're right! I need to get you more info here. Either there's something going with the name itself that the file system doesn't like (an encoding that blows up the name length??) or perhaps there's something with the path that's causing the entire string to  be used as a name. I haven't seen this on any system before and the Internet's not forthcoming with any info.
## Describe the bug

Getting the following error when calling `load_dataset("gar1t/test")`:

```
OSError: [Errno 36] File name too long: '<user>/.cache/huggingface/datasets/_home_garrett_.cache_huggingface_datasets_csv_test-7c856aea083a7043_0.0.0_9144e0a4e8435090117cea53e6c7537173ef2304525df4a077c435d8ee7828ff.incomplete.lock'
```

## Steps to reproduce the bug

Where the user cache dir (e.g. `~/.cache`) is on a file system that limits filenames to 255 chars (e.g. ext4):

```python
from datasets import load_dataset
load_dataset("gar1t/test")
```

## Expected results

Expect the function to return without an error.

## Actual results

```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<python_venv>/lib/python3.9/site-packages/datasets/load.py", line 1112, in load_dataset
    builder_instance.download_and_prepare(
  File "<python_venv>/lib/python3.9/site-packages/datasets/builder.py", line 644, in download_and_prepare
    self._save_info()
  File "<python_venv>/lib/python3.9/site-packages/datasets/builder.py", line 765, in _save_info
    with FileLock(lock_path):
  File "<python_venv>/lib/python3.9/site-packages/datasets/utils/filelock.py", line 323, in __enter__
    self.acquire()
  File "<python_venv>/lib/python3.9/site-packages/datasets/utils/filelock.py", line 272, in acquire
    self._acquire()
  File "<python_venv>/lib/python3.9/site-packages/datasets/utils/filelock.py", line 403, in _acquire
    fd = os.open(self._lock_file, open_mode)
OSError: [Errno 36] File name too long: '<user>/.cache/huggingface/datasets/_home_garrett_.cache_huggingface_datasets_csv_test-7c856aea083a7043_0.0.0_9144e0a4e8435090117cea53e6c7537173ef2304525df4a077c435d8ee7828ff.incomplete.lock'
```

## Environment info

- `datasets` version: 1.12.1
- Platform: Linux-5.11.0-27-generic-x86_64-with-glibc2.31
- Python version: 3.9.7
- PyArrow version: 5.0.0

"File name too long" error for file locks 
 ## Describe the bug

Getting the following error when calling `load_dataset("gar1t/test")`:

```
OSError: [Errno 36] File name too long: '<user>/.cache/huggingface/datasets/_home_garrett_.cache_huggingface_datasets_csv_test-7c856aea083a7043_0.0.0_9144e0a4e8435090117cea53e6c7537173ef2304525df4a077c435d8ee7828ff.incomplete.lock'
```

## Steps to reproduce the bug

Where the user cache dir (e.g. `~/.cache`) is on a file system that limits filenames to 255 chars (e.g. ext4):

```python
from datasets import load_dataset
load_dataset("gar1t/test")
```

## Expected results

Expect the function to return without an error.

## Actual results

```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<python_venv>/lib/python3.9/site-packages/datasets/load.py", line 1112, in load_dataset
    builder_instance.download_and_prepare(
  File "<python_venv>/lib/python3.9/site-packages/datasets/builder.py", line 644, in download_and_prepare
    self._save_info()
  File "<python_venv>/lib/python3.9/site-packages/datasets/builder.py", line 765, in _save_info
    with FileLock(lock_path):
  File "<python_venv>/lib/python3.9/site-packages/datasets/utils/filelock.py", line 323, in __enter__
    self.acquire()
  File "<python_venv>/lib/python3.9/site-packages/datasets/utils/filelock.py", line 272, in acquire
    self._acquire()
  File "<python_venv>/lib/python3.9/site-packages/datasets/utils/filelock.py", line 403, in _acquire
    fd = os.open(self._lock_file, open_mode)
OSError: [Errno 36] File name too long: '<user>/.cache/huggingface/datasets/_home_garrett_.cache_huggingface_datasets_csv_test-7c856aea083a7043_0.0.0_9144e0a4e8435090117cea53e6c7537173ef2304525df4a077c435d8ee7828ff.incomplete.lock'
```

## Environment info

- `datasets` version: 1.12.1
- Platform: Linux-5.11.0-27-generic-x86_64-with-glibc2.31
- Python version: 3.9.7
- PyArrow version: 5.0.0
 
 Yes, you're right! I need to get you more info here. Either there's something going with the name itself that the file system doesn't like (an encoding that blows up the name length??) or perhaps there's something with the path that's causing the entire string to  be used as a name. I haven't seen this on any system before and the Internet's not forthcoming with any info.