[Qemu-devel] [PATCH v2 3/3] iotests/124: Add cluster_size mismatch test

[John Snow <jsnow@redhat.com>]

If a backing file isn't specified in the target image and the
cluster_size is larger than the bitmap granularity, we run the risk of
creating bitmaps with allocated clusters but empty/no data which will
prevent the proper reading of the backup in the future.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/124     | 58 ++++++++++++++++++++++++++++++++++++++++++----
 tests/qemu-iotests/124.out |  4 ++--
 2 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/tests/qemu-iotests/124 b/tests/qemu-iotests/124
index 7d33422..de7cdbe 100644
--- a/tests/qemu-iotests/124
+++ b/tests/qemu-iotests/124
@@ -132,14 +132,16 @@ class TestIncrementalBackupBase(iotests.QMPTestCase):
 
 
     def img_create(self, img, fmt=iotests.imgfmt, size='64M',
-                   parent=None, parentFormat=None):
+                   parent=None, parentFormat=None, **kwargs):
+        optargs = []
+        for k,v in kwargs.iteritems():
+            optargs = optargs + ['-o', '%s=%s' % (k,v)]
+        args = ['create', '-f', fmt] + optargs + [img, size]
         if parent:
             if parentFormat is None:
                 parentFormat = fmt
-            iotests.qemu_img('create', '-f', fmt, img, size,
-                             '-b', parent, '-F', parentFormat)
-        else:
-            iotests.qemu_img('create', '-f', fmt, img, size)
+            args = args + ['-b', parent, '-F', parentFormat]
+        iotests.qemu_img(*args)
         self.files.append(img)
 
 
@@ -307,6 +309,52 @@ class TestIncrementalBackup(TestIncrementalBackupBase):
         return self.do_incremental_simple(granularity=131072)
 
 
+    def test_larger_cluster_target(self):
+        '''
+        Test: Create and verify backups made to a larger cluster size target.
+
+        With a default granularity of 64KiB, verify that backups made to a
+        larger cluster size target of 128KiB without a backing file works.
+        '''
+        drive0 = self.drives[0]
+
+        # Create a cluster_size=128k full backup / "anchor" backup
+        self.img_create(drive0['backup'], cluster_size='128k')
+        self.assertTrue(self.do_qmp_backup(device=drive0['id'], sync='full',
+                                           format=drive0['fmt'],
+                                           target=drive0['backup'],
+                                           mode='existing'))
+
+        # Create bitmap and dirty it with some new writes.
+        # overwrite [32736, 32799] which will dirty bitmap clusters at
+        # 32M-64K and 32M. 32M+64K will be left undirtied.
+        bitmap0 = self.add_bitmap('bitmap0', drive0)
+        self.hmp_io_writes(drive0['id'],
+                           (('0xab', 0, 512),
+                            ('0xfe', '16M', '256k'),
+                            ('0x64', '32736k', '64k')))
+
+
+        # Prepare a cluster_size=128k backup target without a backing file.
+        (target, _) = bitmap0.new_target()
+        self.img_create(target, bitmap0.drive['fmt'], cluster_size='128k')
+
+        # Perform Incremental Backup
+        self.assertTrue(self.do_qmp_backup(device=bitmap0.drive['id'],
+                                           sync='incremental',
+                                           bitmap=bitmap0.name,
+                                           format=bitmap0.drive['fmt'],
+                                           target=target,
+                                           mode='existing'))
+        self.make_reference_backup(bitmap0)
+
+        # Add the backing file, then compare and exit.
+        iotests.qemu_img('rebase', '-f', drive0['fmt'], '-u', '-b',
+                         drive0['backup'], '-F', drive0['fmt'], target)
+        self.vm.shutdown()
+        self.check_backups()
+
+
     def test_incremental_transaction(self):
         '''Test: Verify backups made from transactionally created bitmaps.
 
diff --git a/tests/qemu-iotests/124.out b/tests/qemu-iotests/124.out
index dae404e..36376be 100644
--- a/tests/qemu-iotests/124.out
+++ b/tests/qemu-iotests/124.out
@@ -1,5 +1,5 @@
-.........
+..........
 ----------------------------------------------------------------------
-Ran 9 tests
+Ran 10 tests
 
 OK
-- 
2.4.3