storage: add size and usage properties to pool object

Add Pool.size and Pool.usage to the API. Implement them for LVM and File
pools. Add appropriate tests.

QubesOS/qubes-issues#3240

qubes/storage/__init__.py

@@ -815,6 +815,16 @@ class Pool(object):
         '''
         raise self._not_implemented("get_volume")
 
+    @property
+    def size(self):
+        ''' Storage pool size in bytes '''
+        raise self._not_implemented("size")
+
+    @property
+    def usage(self):
+        ''' Space used in the pool, in bytes '''
+        raise self._not_implemented("usage")
+
     def _not_implemented(self, method_name):
         ''' Helper for emitting helpful `NotImplementedError` exceptions '''
         msg = "Pool driver {!s} has {!s}() not implemented"

qubes/storage/file.py

@@ -144,6 +144,16 @@ class FilePool(qubes.storage.Pool):
     def list_volumes(self):
         return self._volumes
 
+    @property
+    def size(self):
+        statvfs = os.statvfs(self.dir_path)
+        return statvfs.f_frsize * statvfs.f_blocks
+
+    @property
+    def usage(self):
+        statvfs = os.statvfs(self.dir_path)
+        return statvfs.f_frsize * (statvfs.f_blocks - statvfs.f_bfree)
+
 
 class FileVolume(qubes.storage.Volume):
     ''' Parent class for the xen volumes implementation which expects a

qubes/storage/lvm.py

@@ -137,6 +137,22 @@ class ThinPool(qubes.storage.Pool):
             volumes += [ThinVolume(**config)]
         return volumes
 
+    @property
+    def size(self):
+        try:
+            return qubes.storage.lvm.size_cache[
+                self.volume_group + '/' + self.thin_pool]['size']
+        except KeyError:
+            return 0
+
+    @property
+    def usage(self):
+        try:
+            return qubes.storage.lvm.size_cache[
+                self.volume_group + '/' + self.thin_pool]['usage']
+        except KeyError:
+            return 0
+
 
 def init_cache(log=logging.getLogger('qubes.storage.lvm')):
     cmd = ['lvs', '--noheadings', '-o',
@@ -159,7 +175,7 @@ def init_cache(log=logging.getLogger('qubes.storage.lvm')):
         line = line.decode().strip()
         pool_name, pool_lv, name, size, usage_percent, attr, \
             origin = line.split(';', 6)
-        if '' in [pool_name, pool_lv, name, size, usage_percent]:
+        if '' in [pool_name, name, size, usage_percent]:
             continue
         name = pool_name + "/" + name
         size = int(size[:-1])  # Remove 'B' suffix

qubes/tests/storage_file.py

@@ -369,6 +369,21 @@ class TC_03_FilePool(qubes.tests.QubesTestCase):
 
         shutil.rmtree(pool_dir, ignore_errors=True)
 
+    def test_003_size(self):
+        pool = self.app.get_pool(self.POOL_NAME)
+        with self.assertNotRaises(NotImplementedError):
+            size = pool.size
+        statvfs = os.statvfs(self.POOL_DIR)
+        self.assertEqual(size, statvfs.f_blocks * statvfs.f_frsize)
+
+    def test_004_usage(self):
+        pool = self.app.get_pool(self.POOL_NAME)
+        with self.assertNotRaises(NotImplementedError):
+            usage = pool.usage
+        statvfs = os.statvfs(self.POOL_DIR)
+        self.assertEqual(usage,
+            statvfs.f_frsize * (statvfs.f_blocks - statvfs.f_bfree))
+
     def test_011_appvm_file_images(self):
         """ Check if all the needed image files are created for an AppVm"""
 

qubes/tests/storage_lvm.py

@@ -26,6 +26,7 @@
 '''
 
 import os
+import subprocess
 import unittest
 
 import qubes.tests
@@ -158,6 +159,26 @@ class TC_00_ThinPool(ThinPoolBase):
         self.assertTrue(os.path.exists(path))
         volume.remove()
 
+    def test_004_size(self):
+        with self.assertNotRaises(NotImplementedError):
+            size = self.pool.size
+        pool_size = subprocess.check_output(['sudo', 'lvs', '--noheadings',
+            '-o', 'lv_size',
+            '--units', 'b', self.pool.volume_group + '/' + self.pool.thin_pool])
+        self.assertEqual(size, int(pool_size.strip()[:-1]))
+
+    def test_005_usage(self):
+        with self.assertNotRaises(NotImplementedError):
+            usage = self.pool.usage
+        pool_info = subprocess.check_output(['sudo', 'lvs', '--noheadings',
+            '-o', 'lv_size,data_percent',
+            '--units', 'b', self.pool.volume_group + '/' + self.pool.thin_pool])
+        pool_size, pool_usage = pool_info.strip().split()
+        pool_size = int(pool_size[:-1])
+        pool_usage = float(pool_usage)
+        self.assertEqual(usage, int(pool_size * pool_usage / 100))
+
+
 @skipUnlessLvmPoolExists
 class TC_01_ThinPool(ThinPoolBase, qubes.tests.SystemTestCase):
     ''' Sanity tests for :py:class:`qubes.storage.lvm.ThinPool` '''