bitmaps patches for 2020-08-03

- fix bitmap migration involving read-only bitmap from backing chain
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Merge remote-tracking branch 'remotes/ericb/tags/pull-bitmaps-2020-08-03' into staging

bitmaps patches for 2020-08-03

- fix bitmap migration involving read-only bitmap from backing chain

# gpg: Signature made Mon 03 Aug 2020 15:06:51 BST
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-bitmaps-2020-08-03:
  iotests/169: Test source cont with backing bmap
  qcow2: Release read-only bitmaps when inactivated

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block/qcow2-bitmap.c

@@ -1562,11 +1562,22 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
         Qcow2Bitmap *bm;
 
         if (!bdrv_dirty_bitmap_get_persistence(bitmap) ||
-            bdrv_dirty_bitmap_readonly(bitmap) ||
             bdrv_dirty_bitmap_inconsistent(bitmap)) {
             continue;
         }
 
+        if (bdrv_dirty_bitmap_readonly(bitmap)) {
+            /*
+             * Store the bitmap in the associated Qcow2Bitmap so it
+             * can be released later
+             */
+            bm = find_bitmap_by_name(bm_list, name);
+            if (bm) {
+                bm->dirty_bitmap = bitmap;
+            }
+            continue;
+        }
+
         need_write = true;
 
         if (check_constraints_on_bitmap(bs, name, granularity, errp) < 0) {
@@ -1618,7 +1629,9 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
 
     /* allocate clusters and store bitmaps */
     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
-        if (bm->dirty_bitmap == NULL) {
+        BdrvDirtyBitmap *bitmap = bm->dirty_bitmap;
+
+        if (bitmap == NULL || bdrv_dirty_bitmap_readonly(bitmap)) {
             continue;
         }
 
@@ -1641,6 +1654,7 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
         g_free(tb);
     }
 
+success:
     if (release_stored) {
         QSIMPLEQ_FOREACH(bm, bm_list, entry) {
             if (bm->dirty_bitmap == NULL) {
@@ -1651,13 +1665,14 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
         }
     }
 
-success:
     bitmap_list_free(bm_list);
     return;
 
 fail:
     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
-        if (bm->dirty_bitmap == NULL || bm->table.offset == 0) {
+        if (bm->dirty_bitmap == NULL || bm->table.offset == 0 ||
+            bdrv_dirty_bitmap_readonly(bm->dirty_bitmap))
+        {
             continue;
         }
 

tests/qemu-iotests/169

@@ -24,11 +24,12 @@ import time
 import itertools
 import operator
 import re
-from iotests import qemu_img
+from iotests import qemu_img, qemu_img_create, Timeout
 
 
 disk_a = os.path.join(iotests.test_dir, 'disk_a')
 disk_b = os.path.join(iotests.test_dir, 'disk_b')
+base_a = os.path.join(iotests.test_dir, 'base_a')
 size = '1M'
 mig_file = os.path.join(iotests.test_dir, 'mig_file')
 mig_cmd = 'exec: cat > ' + mig_file
@@ -234,6 +235,67 @@ for cmb in list(itertools.product((True, False), repeat=2)):
     inject_test_case(TestDirtyBitmapMigration, name,
                      'do_test_migration_resume_source', *list(cmb))
 
+
+class TestDirtyBitmapBackingMigration(iotests.QMPTestCase):
+    def setUp(self):
+        qemu_img_create('-f', iotests.imgfmt, base_a, size)
+        qemu_img_create('-f', iotests.imgfmt, '-F', iotests.imgfmt,
+                        '-b', base_a, disk_a, size)
+
+        for f in (disk_a, base_a):
+            qemu_img('bitmap', '--add', f, 'bmap0')
+
+        blockdev = {
+            'node-name': 'node0',
+            'driver': iotests.imgfmt,
+            'file': {
+                'driver': 'file',
+                'filename': disk_a
+            },
+            'backing': {
+                'node-name': 'node0-base',
+                'driver': iotests.imgfmt,
+                'file': {
+                    'driver': 'file',
+                    'filename': base_a
+                }
+            }
+        }
+
+        self.vm = iotests.VM()
+        self.vm.launch()
+
+        result = self.vm.qmp('blockdev-add', **blockdev)
+        self.assert_qmp(result, 'return', {})
+
+        # Check that the bitmaps are there
+        for node in self.vm.qmp('query-named-block-nodes', flat=True)['return']:
+            if 'node0' in node['node-name']:
+                self.assert_qmp(node, 'dirty-bitmaps[0]/name', 'bmap0')
+
+        caps = [{'capability': 'events', 'state': True}]
+        result = self.vm.qmp('migrate-set-capabilities', capabilities=caps)
+        self.assert_qmp(result, 'return', {})
+
+    def tearDown(self):
+        self.vm.shutdown()
+        for f in (disk_a, base_a):
+            os.remove(f)
+
+    def test_cont_on_source(self):
+        """
+        Continue the source after migration.
+        """
+        result = self.vm.qmp('migrate', uri=f'exec: cat > /dev/null')
+        self.assert_qmp(result, 'return', {})
+
+        with Timeout(10, 'Migration timeout'):
+            self.vm.wait_migration('postmigrate')
+
+        result = self.vm.qmp('cont')
+        self.assert_qmp(result, 'return', {})
+
+
 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2'],
                  supported_protocols=['file'])

tests/qemu-iotests/169.out

@@ -1,5 +1,5 @@
-....................................
+.....................................
 ----------------------------------------------------------------------
-Ran 36 tests
+Ran 37 tests
 
 OK