storage/reflink: simplify volume.usage()

qubes/storage/reflink.py

@@ -36,7 +36,6 @@ from contextlib import contextmanager, suppress
 
 import qubes.storage
 
-BLKSIZE = 512
 FICLONE = 1074041865        # defined in <linux/fs.h>
 LOOP_SET_CAPACITY = 0x4C07  # defined in <linux/loop.h>
 LOGGER = logging.getLogger('qubes.storage.reflink')
@@ -342,10 +341,9 @@ class ReflinkVolume(qubes.storage.Volume):
         ''' Return volume disk usage from the VM's perspective. It is
             usually much lower from the host's perspective due to CoW.
         '''
-        with suppress(FileNotFoundError):
-            return _get_file_disk_usage(self._path_dirty)
-        with suppress(FileNotFoundError):
-            return _get_file_disk_usage(self._path_clean)
+        for path in (self._path_dirty, self._path_clean):
+            with suppress(FileNotFoundError):
+                return os.stat(path).st_blocks * 512
         return 0
 
 
@@ -369,10 +367,6 @@ def _replace_file(dst):
         _remove_file(tmp.name)
         raise
 
-def _get_file_disk_usage(path):
-    ''' Return real disk usage (not logical file size) of a file. '''
-    return os.stat(path).st_blocks * BLKSIZE
-
 def _fsync_dir(path):
     dir_fd = os.open(path, os.O_RDONLY | os.O_DIRECTORY)
     try:

qubes/tests/storage_reflink.py

@@ -62,15 +62,17 @@ class ReflinkMixin:
 
         os.symlink(img_real, img_sym)
         reflink._create_sparse_file(img_real, size_initial)
-        self.assertEqual(reflink._get_file_disk_usage(img_real), 0)
-        self.assertEqual(os.stat(img_real).st_size, size_initial)
+        stat = os.stat(img_real)
+        self.assertEqual(stat.st_blocks, 0)
+        self.assertEqual(stat.st_size, size_initial)
 
         dev_from_real = setup_loopdev(img_real, cleanup_via=self.addCleanup)
         dev_from_sym = setup_loopdev(img_sym, cleanup_via=self.addCleanup)
 
         reflink._resize_file(img_real, size_resized)
-        self.assertEqual(reflink._get_file_disk_usage(img_real), 0)
-        self.assertEqual(os.stat(img_real).st_size, size_resized)
+        stat = os.stat(img_real)
+        self.assertEqual(stat.st_blocks, 0)
+        self.assertEqual(stat.st_size, size_resized)
 
         reflink_update_loopdev_sizes(os.path.join(self.test_dir, 'unrelated'))