iotests: Test committing to overridden backing

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/040

@@ -911,6 +911,67 @@ class TestCommitWithFilters(iotests.QMPTestCase):
         # 3 has been comitted into 2
         self.pattern_files[3] = self.img2
 
+class TestCommitWithOverriddenBacking(iotests.QMPTestCase):
+    img_base_a = os.path.join(iotests.test_dir, 'base_a.img')
+    img_base_b = os.path.join(iotests.test_dir, 'base_b.img')
+    img_top = os.path.join(iotests.test_dir, 'top.img')
+
+    def setUp(self):
+        qemu_img('create', '-f', iotests.imgfmt, self.img_base_a, '1M')
+        qemu_img('create', '-f', iotests.imgfmt, self.img_base_b, '1M')
+        qemu_img('create', '-f', iotests.imgfmt, '-b', self.img_base_a, \
+                 self.img_top)
+
+        self.vm = iotests.VM()
+        self.vm.launch()
+
+        # Use base_b instead of base_a as the backing of top
+        result = self.vm.qmp('blockdev-add', **{
+                                'node-name': 'top',
+                                'driver': iotests.imgfmt,
+                                'file': {
+                                    'driver': 'file',
+                                    'filename': self.img_top
+                                },
+                                'backing': {
+                                    'node-name': 'base',
+                                    'driver': iotests.imgfmt,
+                                    'file': {
+                                        'driver': 'file',
+                                        'filename': self.img_base_b
+                                    }
+                                }
+                            })
+        self.assert_qmp(result, 'return', {})
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(self.img_top)
+        os.remove(self.img_base_a)
+        os.remove(self.img_base_b)
+
+    def test_commit_to_a(self):
+        # Try committing to base_a (which should fail, as top's
+        # backing image is base_b instead)
+        result = self.vm.qmp('block-commit',
+                             job_id='commit',
+                             device='top',
+                             base=self.img_base_a)
+        self.assert_qmp(result, 'error/class', 'GenericError')
+
+    def test_commit_to_b(self):
+        # Try committing to base_b (which should work, since that is
+        # actually top's backing image)
+        result = self.vm.qmp('block-commit',
+                             job_id='commit',
+                             device='top',
+                             base=self.img_base_b)
+        self.assert_qmp(result, 'return', {})
+
+        self.vm.event_wait('BLOCK_JOB_READY')
+        self.vm.qmp('block-job-complete', device='commit')
+        self.vm.event_wait('BLOCK_JOB_COMPLETED')
+
 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2', 'qed'],
                  supported_protocols=['file'])

tests/qemu-iotests/040.out

@@ -1,5 +1,5 @@
-...............................................................
+.................................................................
 ----------------------------------------------------------------------
-Ran 63 tests
+Ran 65 tests
 
 OK