The cluster size of an image is the QcowHeader class member and may be
obtained by dependent extension structures such as Qcow2BitmapExt for
further bitmap table details print.

Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
 tests/qemu-iotests/qcow2_format.py | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_format.py
index 90eff92..eb99119 100644
--- a/tests/qemu-iotests/qcow2_format.py
+++ b/tests/qemu-iotests/qcow2_format.py
@@ -116,6 +116,10 @@ class Qcow2BitmapExt(Qcow2Struct):
         ('u64', '{:#x}', 'bitmap_directory_offset')
     )
 
+    def __init__(self, data, cluster_size):
+        super().__init__(data=data)
+        self.cluster_size = cluster_size
+
     def read_bitmap_directory(self, fd):
         self.bitmaps = []
         fd.seek(self.bitmap_directory_offset)
@@ -123,7 +127,8 @@ class Qcow2BitmapExt(Qcow2Struct):
 
         for n in range(self.nb_bitmaps):
             buf = fd.read(buf_size)
-            dir_entry = Qcow2BitmapDirEntry(data=buf)
+            dir_entry = Qcow2BitmapDirEntry(data=buf,
+                                            cluster_size=self.cluster_size)
             fd.seek(dir_entry.extra_data_size, FROM_CURRENT)
             bitmap_name = fd.read(dir_entry.name_size)
             dir_entry.name = bitmap_name.decode('ascii')
@@ -159,8 +164,9 @@ class Qcow2BitmapDirEntry(Qcow2Struct):
         ('u32', '{}',    'extra_data_size')
     )
 
-    def __init__(self, data):
+    def __init__(self, data, cluster_size):
         super().__init__(data=data)
+        self.cluster_size = cluster_size
 
         self.bitmap_table_bytes = self.bitmap_table_size \
             * struct.calcsize('Q')
@@ -205,11 +211,13 @@ class QcowHeaderExtension(Qcow2Struct):
         # then padding to next multiply of 8
     )
 
-    def __init__(self, magic=None, length=None, data=None, fd=None):
+    def __init__(self, magic=None, length=None, data=None, fd=None,
+                 cluster_size=None):
         """
         Support both loading from fd and creation from user data.
         For fd-based creation current position in a file will be used to read
         the data.
+        The cluster_size value may be obtained by dependent structures.
 
         This should be somehow refactored and functionality should be moved to
         superclass (to allow creation of any qcow2 struct), but then, fields
@@ -243,7 +251,8 @@ class QcowHeaderExtension(Qcow2Struct):
         self.data_str = data_str
 
         if self.magic == QCOW2_EXT_MAGIC_BITMAPS:
-            self.obj = Qcow2BitmapExt(data=self.data)
+            self.obj = Qcow2BitmapExt(data=self.data,
+                                      cluster_size=cluster_size)
         else:
             self.obj = None
 
@@ -318,7 +327,7 @@ class QcowHeader(Qcow2Struct):
             end = self.cluster_size
 
         while fd.tell() < end:
-            ext = QcowHeaderExtension(fd=fd)
+            ext = QcowHeaderExtension(fd=fd, cluster_size=self.cluster_size)
             if ext.magic == 0:
                 break
             else:
-- 
1.8.3.1