Implement get_volume_stats for GlusterFS driver

Implement get_volume_stats(), so that the GlusterFS driver
will work correctly with the scheduler.

Fixes bug: 1164038

Change-Id: Ib4db8bad897212227b39704e2e6cb5f07f2bb70e

cinder/tests/test_glusterfs.py

@@ -255,10 +255,11 @@ def test_get_available_capacity_with_df(self):
         mox = self._mox
         drv = self._driver
 
+        df_total_size = 2620544
         df_avail = 1490560
         df_head = 'Filesystem 1K-blocks Used Available Use% Mounted on\n'
-        df_data = 'glusterfs-host:/export 2620544 996864 %d 41%% /mnt' % \
-            df_avail
+        df_data = 'glusterfs-host:/export %d 996864 %d 41%% /mnt' % \
+                  (df_total_size, df_avail)
         df_output = df_head + df_data
 
         setattr(glusterfs.FLAGS, 'glusterfs_disk_util', 'df')
@@ -274,7 +275,7 @@ def test_get_available_capacity_with_df(self):
 
         mox.ReplayAll()
 
-        self.assertEquals(df_avail,
+        self.assertEquals((df_avail, df_total_size),
                           drv._get_available_capacity(
                               self.TEST_EXPORT1))
 
@@ -319,7 +320,7 @@ def test_get_available_capacity_with_du(self):
 
         mox.ReplayAll()
 
-        self.assertEquals(df_total_size - du_used,
+        self.assertEquals((df_total_size - du_used, df_total_size),
                           drv._get_available_capacity(
                               self.TEST_EXPORT1))
 
@@ -450,9 +451,9 @@ def test_find_share(self):
 
         mox.StubOutWithMock(drv, '_get_available_capacity')
         drv._get_available_capacity(self.TEST_EXPORT1).\
-            AndReturn(2 * self.ONE_GB_IN_BYTES)
+            AndReturn((2 * self.ONE_GB_IN_BYTES, 5 * self.ONE_GB_IN_BYTES))
         drv._get_available_capacity(self.TEST_EXPORT2).\
-            AndReturn(3 * self.ONE_GB_IN_BYTES)
+            AndReturn((3 * self.ONE_GB_IN_BYTES, 10 * self.ONE_GB_IN_BYTES))
 
         mox.ReplayAll()
 
@@ -471,9 +472,9 @@ def test_find_share_should_throw_error_if_there_is_no_enough_place(self):
 
         mox.StubOutWithMock(drv, '_get_available_capacity')
         drv._get_available_capacity(self.TEST_EXPORT1).\
-            AndReturn(0)
+            AndReturn((0, 5 * self.ONE_GB_IN_BYTES))
         drv._get_available_capacity(self.TEST_EXPORT2).\
-            AndReturn(0)
+            AndReturn((0, 10 * self.ONE_GB_IN_BYTES))
 
         mox.ReplayAll()
 

cinder/volume/drivers/glusterfs.py

@@ -200,7 +200,7 @@ def _find_share(self, volume_size_for):
         greatest_share = None
 
         for glusterfs_share in self._mounted_shares:
-            capacity = self._get_available_capacity(glusterfs_share)
+            capacity = self._get_available_capacity(glusterfs_share)[0]
             if capacity > greatest_size:
                 greatest_share = glusterfs_share
                 greatest_size = capacity
@@ -229,17 +229,17 @@ def _get_available_capacity(self, glusterfs_share):
 
         available = 0
 
+        size = int(out.split()[1])
         if self.configuration.glusterfs_disk_util == 'df':
             available = int(out.split()[3])
         else:
-            size = int(out.split()[1])
             out, _ = self._execute('du', '-sb', '--apparent-size',
                                    '--exclude', '*snapshot*', mount_point,
                                    run_as_root=True)
             used = int(out.split()[0])
             available = size - used
 
-        return available
+        return available, size
 
     def _mount_glusterfs(self, glusterfs_share, mount_path, ensure=False):
         """Mount GlusterFS share to mount path."""
@@ -254,3 +254,37 @@ def _mount_glusterfs(self, glusterfs_share, mount_path, ensure=False):
                 LOG.warn(_("%s is already mounted"), glusterfs_share)
             else:
                 raise
+
+    def get_volume_stats(self, refresh=False):
+        """Get volume stats.
+
+        If 'refresh' is True, update the stats first."""
+        if refresh or not self._stats:
+            self._update_volume_stats()
+
+        return self._stats
+
+    def _update_volume_stats(self):
+        """Retrieve stats info from volume group."""
+
+        data = {}
+        backend_name = self.configuration.safe_get('volume_backend_name')
+        data['volume_backend_name'] = backend_name or 'GlusterFS'
+        data['vendor_name'] = 'Open Source'
+        data['driver_version'] = '1.0'
+        data['storage_protocol'] = 'glusterfs'
+
+        self._ensure_shares_mounted()
+
+        global_capacity = 0
+        global_free = 0
+        for nfs_share in self._mounted_shares:
+            free, capacity = self._get_available_capacity(nfs_share)
+            global_capacity += capacity
+            global_free += free
+
+        data['total_capacity_gb'] = global_capacity / 1024.0 ** 3
+        data['free_capacity_gb'] = global_free / 1024.0 ** 3
+        data['reserved_percentage'] = 0
+        data['QoS_support'] = False
+        self._stats = data