Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches:

- Fix check_to_replace_node()
- commit: Expose on-error option in QMP
- qcow2: Fix qcow2_alloc_cluster_abort() for external data file
- mirror: Fix deadlock
- vvfat: Fix segfault while closing read-write node
- Code cleanups

# gpg: Signature made Tue 18 Feb 2020 14:04:43 GMT
# gpg:                using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream: (36 commits)
  iotests: Check that @replaces can replace filters
  iotests: Add tests for invalid Quorum @replaces
  iotests: Use self.image_len in TestRepairQuorum
  iotests: Resolve TODOs in 041
  iotests/041: Drop superfluous shutdowns
  iotests: Add VM.assert_block_path()
  iotests: Use complete_and_wait() in 155
  quorum: Stop marking it as a filter
  mirror: Double-check immediately before replacing
  block: Remove bdrv_recurse_is_first_non_filter()
  block: Use bdrv_recurse_can_replace()
  quorum: Implement .bdrv_recurse_can_replace()
  blkverify: Implement .bdrv_recurse_can_replace()
  block: Add bdrv_recurse_can_replace()
  quorum: Fix child permissions
  iotests: Let 041 use -blockdev for quorum children
  block: Drop bdrv_is_first_non_filter()
  blockdev: Allow resizing everywhere
  blockdev: Allow external snapshots everywhere
  block/io_uring: Remove superfluous semicolon
  ...

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

8 files changed, 488 insertions, 27 deletions

diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
index 2e7ee0e84f..32c82b4ec6 100755
--- a/tests/qemu-iotests/040
+++ b/tests/qemu-iotests/040
@@ -430,6 +430,289 @@ class TestReopenOverlay(ImageCommitTestCase):
     def test_reopen_overlay(self):
         self.run_commit_test(self.img1, self.img0)
 
+class TestErrorHandling(iotests.QMPTestCase):
+    image_len = 2 * 1024 * 1024
+
+    def setUp(self):
+        iotests.create_image(backing_img, self.image_len)
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % backing_img, mid_img)
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % mid_img, test_img)
+
+        qemu_io('-f', iotests.imgfmt, '-c', 'write -P 0x11 0 512k', mid_img)
+        qemu_io('-f', iotests.imgfmt, '-c', 'write -P 0x22 0 512k', test_img)
+
+        self.vm = iotests.VM()
+        self.vm.launch()
+
+        self.blkdebug_file = iotests.file_path("blkdebug.conf")
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(test_img)
+        os.remove(mid_img)
+        os.remove(backing_img)
+
+    def blockdev_add(self, **kwargs):
+        result = self.vm.qmp('blockdev-add', **kwargs)
+        self.assert_qmp(result, 'return', {})
+
+    def add_block_nodes(self, base_debug=None, mid_debug=None, top_debug=None):
+        self.blockdev_add(node_name='base-file', driver='file',
+                          filename=backing_img)
+        self.blockdev_add(node_name='mid-file', driver='file',
+                          filename=mid_img)
+        self.blockdev_add(node_name='top-file', driver='file',
+                          filename=test_img)
+
+        if base_debug:
+            self.blockdev_add(node_name='base-dbg', driver='blkdebug',
+                              image='base-file', inject_error=base_debug)
+        if mid_debug:
+            self.blockdev_add(node_name='mid-dbg', driver='blkdebug',
+                              image='mid-file', inject_error=mid_debug)
+        if top_debug:
+            self.blockdev_add(node_name='top-dbg', driver='blkdebug',
+                              image='top-file', inject_error=top_debug)
+
+        self.blockdev_add(node_name='base-fmt', driver='raw',
+                          file=('base-dbg' if base_debug else 'base-file'))
+        self.blockdev_add(node_name='mid-fmt', driver=iotests.imgfmt,
+                          file=('mid-dbg' if mid_debug else 'mid-file'),
+                          backing='base-fmt')
+        self.blockdev_add(node_name='top-fmt', driver=iotests.imgfmt,
+                          file=('top-dbg' if top_debug else 'top-file'),
+                          backing='mid-fmt')
+
+    def run_job(self, expected_events, error_pauses_job=False):
+        match_device = {'data': {'device': 'job0'}}
+        events = [
+            ('BLOCK_JOB_COMPLETED', match_device),
+            ('BLOCK_JOB_CANCELLED', match_device),
+            ('BLOCK_JOB_ERROR', match_device),
+            ('BLOCK_JOB_READY', match_device),
+        ]
+
+        completed = False
+        log = []
+        while not completed:
+            ev = self.vm.events_wait(events, timeout=5.0)
+            if ev['event'] == 'BLOCK_JOB_COMPLETED':
+                completed = True
+            elif ev['event'] == 'BLOCK_JOB_ERROR':
+                if error_pauses_job:
+                    result = self.vm.qmp('block-job-resume', device='job0')
+                    self.assert_qmp(result, 'return', {})
+            elif ev['event'] == 'BLOCK_JOB_READY':
+                result = self.vm.qmp('block-job-complete', device='job0')
+                self.assert_qmp(result, 'return', {})
+            else:
+                self.fail("Unexpected event: %s" % ev)
+            log.append(iotests.filter_qmp_event(ev))
+
+        self.maxDiff = None
+        self.assertEqual(expected_events, log)
+
+    def event_error(self, op, action):
+        return {
+            'event': 'BLOCK_JOB_ERROR',
+            'data': {'action': action, 'device': 'job0', 'operation': op},
+            'timestamp': {'microseconds': 'USECS', 'seconds': 'SECS'}
+        }
+
+    def event_ready(self):
+        return {
+            'event': 'BLOCK_JOB_READY',
+            'data': {'device': 'job0',
+                     'len': 524288,
+                     'offset': 524288,
+                     'speed': 0,
+                     'type': 'commit'},
+            'timestamp': {'microseconds': 'USECS', 'seconds': 'SECS'},
+        }
+
+    def event_completed(self, errmsg=None, active=True):
+        max_len = 524288 if active else self.image_len
+        data = {
+            'device': 'job0',
+            'len': max_len,
+            'offset': 0 if errmsg else max_len,
+            'speed': 0,
+            'type': 'commit'
+        }
+        if errmsg:
+            data['error'] = errmsg
+
+        return {
+            'event': 'BLOCK_JOB_COMPLETED',
+            'data': data,
+            'timestamp': {'microseconds': 'USECS', 'seconds': 'SECS'},
+        }
+
+    def blkdebug_event(self, event, is_raw=False):
+        if event:
+            return [{
+                'event': event,
+                'sector': 512 if is_raw else 1024,
+                'once': True,
+            }]
+        return None
+
+    def prepare_and_start_job(self, on_error, active=True,
+                              top_event=None, mid_event=None, base_event=None):
+
+        top_debug = self.blkdebug_event(top_event)
+        mid_debug = self.blkdebug_event(mid_event)
+        base_debug = self.blkdebug_event(base_event, True)
+
+        self.add_block_nodes(top_debug=top_debug, mid_debug=mid_debug,
+                             base_debug=base_debug)
+
+        result = self.vm.qmp('block-commit', job_id='job0', device='top-fmt',
+                             top_node='top-fmt' if active else 'mid-fmt',
+                             base_node='mid-fmt' if active else 'base-fmt',
+                             on_error=on_error)
+        self.assert_qmp(result, 'return', {})
+
+    def testActiveReadErrorReport(self):
+        self.prepare_and_start_job('report', top_event='read_aio')
+        self.run_job([
+            self.event_error('read', 'report'),
+            self.event_completed('Input/output error')
+        ])
+
+        self.vm.shutdown()
+        self.assertFalse(iotests.compare_images(test_img, mid_img),
+                         'target image matches source after error')
+
+    def testActiveReadErrorStop(self):
+        self.prepare_and_start_job('stop', top_event='read_aio')
+        self.run_job([
+            self.event_error('read', 'stop'),
+            self.event_ready(),
+            self.event_completed()
+        ], error_pauses_job=True)
+
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(test_img, mid_img),
+                        'target image does not match source after commit')
+
+    def testActiveReadErrorIgnore(self):
+        self.prepare_and_start_job('ignore', top_event='read_aio')
+        self.run_job([
+            self.event_error('read', 'ignore'),
+            self.event_ready(),
+            self.event_completed()
+        ])
+
+        # For commit, 'ignore' actually means retry, so this will succeed
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(test_img, mid_img),
+                        'target image does not match source after commit')
+
+    def testActiveWriteErrorReport(self):
+        self.prepare_and_start_job('report', mid_event='write_aio')
+        self.run_job([
+            self.event_error('write', 'report'),
+            self.event_completed('Input/output error')
+        ])
+
+        self.vm.shutdown()
+        self.assertFalse(iotests.compare_images(test_img, mid_img),
+                         'target image matches source after error')
+
+    def testActiveWriteErrorStop(self):
+        self.prepare_and_start_job('stop', mid_event='write_aio')
+        self.run_job([
+            self.event_error('write', 'stop'),
+            self.event_ready(),
+            self.event_completed()
+        ], error_pauses_job=True)
+
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(test_img, mid_img),
+                        'target image does not match source after commit')
+
+    def testActiveWriteErrorIgnore(self):
+        self.prepare_and_start_job('ignore', mid_event='write_aio')
+        self.run_job([
+            self.event_error('write', 'ignore'),
+            self.event_ready(),
+            self.event_completed()
+        ])
+
+        # For commit, 'ignore' actually means retry, so this will succeed
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(test_img, mid_img),
+                        'target image does not match source after commit')
+
+    def testIntermediateReadErrorReport(self):
+        self.prepare_and_start_job('report', active=False, mid_event='read_aio')
+        self.run_job([
+            self.event_error('read', 'report'),
+            self.event_completed('Input/output error', active=False)
+        ])
+
+        self.vm.shutdown()
+        self.assertFalse(iotests.compare_images(mid_img, backing_img, fmt2='raw'),
+                         'target image matches source after error')
+
+    def testIntermediateReadErrorStop(self):
+        self.prepare_and_start_job('stop', active=False, mid_event='read_aio')
+        self.run_job([
+            self.event_error('read', 'stop'),
+            self.event_completed(active=False)
+        ], error_pauses_job=True)
+
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(mid_img, backing_img, fmt2='raw'),
+                        'target image does not match source after commit')
+
+    def testIntermediateReadErrorIgnore(self):
+        self.prepare_and_start_job('ignore', active=False, mid_event='read_aio')
+        self.run_job([
+            self.event_error('read', 'ignore'),
+            self.event_completed(active=False)
+        ])
+
+        # For commit, 'ignore' actually means retry, so this will succeed
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(mid_img, backing_img, fmt2='raw'),
+                        'target image does not match source after commit')
+
+    def testIntermediateWriteErrorReport(self):
+        self.prepare_and_start_job('report', active=False, base_event='write_aio')
+        self.run_job([
+            self.event_error('write', 'report'),
+            self.event_completed('Input/output error', active=False)
+        ])
+
+        self.vm.shutdown()
+        self.assertFalse(iotests.compare_images(mid_img, backing_img, fmt2='raw'),
+                         'target image matches source after error')
+
+    def testIntermediateWriteErrorStop(self):
+        self.prepare_and_start_job('stop', active=False, base_event='write_aio')
+        self.run_job([
+            self.event_error('write', 'stop'),
+            self.event_completed(active=False)
+        ], error_pauses_job=True)
+
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(mid_img, backing_img, fmt2='raw'),
+                        'target image does not match source after commit')
+
+    def testIntermediateWriteErrorIgnore(self):
+        self.prepare_and_start_job('ignore', active=False, base_event='write_aio')
+        self.run_job([
+            self.event_error('write', 'ignore'),
+            self.event_completed(active=False)
+        ])
+
+        # For commit, 'ignore' actually means retry, so this will succeed
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(mid_img, backing_img, fmt2='raw'),
+                        'target image does not match source after commit')
+
 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2', 'qed'],
                  supported_protocols=['file'])
diff --git a/tests/qemu-iotests/040.out b/tests/qemu-iotests/040.out
index 220a5fa82c..6a917130b6 100644
--- a/tests/qemu-iotests/040.out
+++ b/tests/qemu-iotests/040.out
@@ -1,5 +1,5 @@
-...............................................
+...........................................................
 ----------------------------------------------------------------------
-Ran 47 tests
+Ran 59 tests
 
 OK
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 43556b9727..5d67bf14bf 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -20,6 +20,7 @@
 
 import time
 import os
+import re
 import iotests
 from iotests import qemu_img, qemu_io
 
@@ -34,6 +35,8 @@ quorum_img3 = os.path.join(iotests.test_dir, 'quorum3.img')
 quorum_repair_img = os.path.join(iotests.test_dir, 'quorum_repair.img')
 quorum_snapshot_file = os.path.join(iotests.test_dir, 'quorum_snapshot.img')
 
+nbd_sock_path = os.path.join(iotests.test_dir, 'nbd.sock')
+
 class TestSingleDrive(iotests.QMPTestCase):
     image_len = 1 * 1024 * 1024 # MB
     qmp_cmd = 'drive-mirror'
@@ -80,7 +83,6 @@ class TestSingleDrive(iotests.QMPTestCase):
         self.cancel_and_wait(force=True)
         result = self.vm.qmp('query-block')
         self.assert_qmp(result, 'return[0]/inserted/file', test_img)
-        self.vm.shutdown()
 
     def test_cancel_after_ready(self):
         self.assert_no_active_block_jobs()
@@ -201,8 +203,6 @@ class TestSingleDrive(iotests.QMPTestCase):
         self.assert_qmp(result, 'return[0]/node-name', 'top')
         self.assert_qmp(result, 'return[0]/backing/node-name', 'base')
 
-        self.vm.shutdown()
-
     def test_medium_not_found(self):
         if iotests.qemu_default_machine != 'pc':
             return
@@ -455,7 +455,6 @@ new_state = "1"
                     self.assert_qmp(event, 'data/id', 'drive0')
 
         self.assert_no_active_block_jobs()
-        self.vm.shutdown()
 
     def test_ignore_read(self):
         self.assert_no_active_block_jobs()
@@ -475,7 +474,6 @@ new_state = "1"
         result = self.vm.qmp('query-block-jobs')
         self.assert_qmp(result, 'return[0]/paused', False)
         self.complete_and_wait()
-        self.vm.shutdown()
 
     def test_large_cluster(self):
         self.assert_no_active_block_jobs()
@@ -540,7 +538,6 @@ new_state = "1"
 
         self.complete_and_wait(wait_ready=False)
         self.assert_no_active_block_jobs()
-        self.vm.shutdown()
 
 class TestWriteErrors(iotests.QMPTestCase):
     image_len = 2 * 1024 * 1024 # MB
@@ -614,7 +611,6 @@ new_state = "1"
                     completed = True
 
         self.assert_no_active_block_jobs()
-        self.vm.shutdown()
 
     def test_ignore_write(self):
         self.assert_no_active_block_jobs()
@@ -631,7 +627,6 @@ new_state = "1"
         result = self.vm.qmp('query-block-jobs')
         self.assert_qmp(result, 'return[0]/paused', False)
         self.complete_and_wait()
-        self.vm.shutdown()
 
     def test_stop_write(self):
         self.assert_no_active_block_jobs()
@@ -667,7 +662,6 @@ new_state = "1"
 
         self.complete_and_wait(wait_ready=False)
         self.assert_no_active_block_jobs()
-        self.vm.shutdown()
 
 class TestSetSpeed(iotests.QMPTestCase):
     image_len = 80 * 1024 * 1024 # MB
@@ -881,11 +875,14 @@ class TestRepairQuorum(iotests.QMPTestCase):
         # Add each individual quorum images
         for i in self.IMAGES:
             qemu_img('create', '-f', iotests.imgfmt, i,
-                     str(TestSingleDrive.image_len))
+                     str(self.image_len))
             # Assign a node name to each quorum image in order to manipulate
             # them
             opts = "node-name=img%i" % self.IMAGES.index(i)
-            self.vm = self.vm.add_drive(i, opts)
+            opts += ',driver=%s' % iotests.imgfmt
+            opts += ',file.driver=file'
+            opts += ',file.filename=%s' % i
+            self.vm = self.vm.add_blockdev(opts)
 
         self.vm.launch()
 
@@ -898,7 +895,8 @@ class TestRepairQuorum(iotests.QMPTestCase):
 
     def tearDown(self):
         self.vm.shutdown()
-        for i in self.IMAGES + [ quorum_repair_img, quorum_snapshot_file ]:
+        for i in self.IMAGES + [ quorum_repair_img, quorum_snapshot_file,
+                                 nbd_sock_path ]:
             # Do a try/except because the test may have deleted some images
             try:
                 os.remove(i)
@@ -915,8 +913,7 @@ class TestRepairQuorum(iotests.QMPTestCase):
 
         self.complete_and_wait(drive="job0")
         self.assert_has_block_node("repair0", quorum_repair_img)
-        # TODO: a better test requiring some QEMU infrastructure will be added
-        #       to check that this file is really driven by quorum
+        self.vm.assert_block_path('quorum0', '/children.1', 'repair0')
         self.vm.shutdown()
         self.assertTrue(iotests.compare_images(quorum_img2, quorum_repair_img),
                         'target image does not match source after mirroring')
@@ -933,7 +930,6 @@ class TestRepairQuorum(iotests.QMPTestCase):
         # here we check that the last registered quorum file has not been
         # swapped out and unref
         self.assert_has_block_node(None, quorum_img3)
-        self.vm.shutdown()
 
     def test_cancel_after_ready(self):
         self.assert_no_active_block_jobs()
@@ -1038,9 +1034,71 @@ class TestRepairQuorum(iotests.QMPTestCase):
 
         self.complete_and_wait('job0')
         self.assert_has_block_node("repair0", quorum_repair_img)
-        # TODO: a better test requiring some QEMU infrastructure will be added
-        #       to check that this file is really driven by quorum
+        self.vm.assert_block_path('quorum0', '/children.1', 'repair0')
+
+    def test_with_other_parent(self):
+        """
+        Check that we cannot replace a Quorum child when it has other
+        parents.
+        """
+        result = self.vm.qmp('nbd-server-start',
+                             addr={
+                                 'type': 'unix',
+                                 'data': {'path': nbd_sock_path}
+                             })
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('nbd-server-add', device='img1')
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('drive-mirror', job_id='mirror', device='quorum0',
+                             sync='full', node_name='repair0', replaces='img1',
+                             target=quorum_repair_img, format=iotests.imgfmt)
+        self.assert_qmp(result, 'error/desc',
+                        "Cannot replace 'img1' by a node mirrored from "
+                        "'quorum0', because it cannot be guaranteed that doing "
+                        "so would not lead to an abrupt change of visible data")
+
+    def test_with_other_parents_after_mirror_start(self):
+        """
+        The same as test_with_other_parent(), but add the NBD server
+        only when the mirror job is already running.
+        """
+        result = self.vm.qmp('nbd-server-start',
+                             addr={
+                                 'type': 'unix',
+                                 'data': {'path': nbd_sock_path}
+                             })
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('drive-mirror', job_id='mirror', device='quorum0',
+                             sync='full', node_name='repair0', replaces='img1',
+                             target=quorum_repair_img, format=iotests.imgfmt)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('nbd-server-add', device='img1')
+        self.assert_qmp(result, 'return', {})
+
+        # The full error message goes to stderr, we will check it later
+        self.complete_and_wait('mirror',
+                               completion_error='Operation not permitted')
+
+        # Should not have been replaced
+        self.vm.assert_block_path('quorum0', '/children.1', 'img1')
+
+        # Check the full error message now
         self.vm.shutdown()
+        log = self.vm.get_log()
+        log = re.sub(r'^\[I \d+\.\d+\] OPENED\n', '', log)
+        log = re.sub(r'^Formatting.*\n', '', log)
+        log = re.sub(r'\n\[I \+\d+\.\d+\] CLOSED\n?$', '', log)
+        log = re.sub(r'^%s: ' % os.path.basename(iotests.qemu_prog), '', log)
+
+        self.assertEqual(log,
+                         "Can no longer replace 'img1' by 'repair0', because " +
+                         "it can no longer be guaranteed that doing so would " +
+                         "not lead to an abrupt change of visible data")
+
 
 # Test mirroring with a source that does not have any parents (not even a
 # BlockBackend)
@@ -1132,6 +1190,52 @@ class TestOrphanedSource(iotests.QMPTestCase):
         self.assertFalse('mirror-filter' in nodes,
                          'Mirror filter node did not disappear')
 
+# Test cases for @replaces that do not necessarily involve Quorum
+class TestReplaces(iotests.QMPTestCase):
+    # Each of these test cases needs their own block graph, so do not
+    # create any nodes here
+    def setUp(self):
+        self.vm = iotests.VM()
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+        for img in (test_img, target_img):
+            try:
+                os.remove(img)
+            except OSError:
+                pass
+
+    @iotests.skip_if_unsupported(['copy-on-read'])
+    def test_replace_filter(self):
+        """
+        Check that we can replace filter nodes.
+        """
+        result = self.vm.qmp('blockdev-add', **{
+                                 'driver': 'copy-on-read',
+                                 'node-name': 'filter0',
+                                 'file': {
+                                     'driver': 'copy-on-read',
+                                     'node-name': 'filter1',
+                                     'file': {
+                                         'driver': 'null-co'
+                                     }
+                                 }
+                             })
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('blockdev-add',
+                             node_name='target', driver='null-co')
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('blockdev-mirror', job_id='mirror', device='filter0',
+                             target='target', sync='full', replaces='filter1')
+        self.assert_qmp(result, 'return', {})
+
+        self.complete_and_wait('mirror')
+
+        self.vm.assert_block_path('filter0', '/file', 'target')
+
 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2', 'qed'],
                  supported_protocols=['file'],
diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
index f496be9197..877b76fd31 100644
--- a/tests/qemu-iotests/041.out
+++ b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-...........................................................................................
+..............................................................................................
 ----------------------------------------------------------------------
-Ran 91 tests
+Ran 94 tests
 
 OK
diff --git a/tests/qemu-iotests/155 b/tests/qemu-iotests/155
index e35b1d534b..f237868710 100755
--- a/tests/qemu-iotests/155
+++ b/tests/qemu-iotests/155
@@ -163,12 +163,7 @@ class MirrorBaseClass(BaseClass):
 
         self.assert_qmp(result, 'return', {})
 
-        self.vm.event_wait('BLOCK_JOB_READY')
-
-        result = self.vm.qmp('block-job-complete', device='mirror-job')
-        self.assert_qmp(result, 'return', {})
-
-        self.vm.event_wait('BLOCK_JOB_COMPLETED')
+        self.complete_and_wait('mirror-job')
 
     def testFull(self):
         self.runMirror('full')
diff --git a/tests/qemu-iotests/244 b/tests/qemu-iotests/244
index 0d1efee6ef..2ec1815e6f 100755
--- a/tests/qemu-iotests/244
+++ b/tests/qemu-iotests/244
@@ -197,6 +197,20 @@ $QEMU_IO -c 'read -P 0x11 0 1M' -f $IMGFMT "$TEST_IMG" | _filter_qemu_io
 $QEMU_IMG map --output=human "$TEST_IMG" | _filter_testdir
 $QEMU_IMG map --output=json "$TEST_IMG"
 
+echo
+echo "=== Copy offloading ==="
+echo
+
+# Make use of copy offloading if the test host can provide it
+_make_test_img -o "data_file=$TEST_IMG.data" 64M
+$QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n -C "$TEST_IMG.src" "$TEST_IMG"
+$QEMU_IMG compare -f $IMGFMT -F $IMGFMT "$TEST_IMG.src" "$TEST_IMG"
+
+# blkdebug doesn't support copy offloading, so this tests the error path
+$QEMU_IMG amend -f $IMGFMT -o "data_file=blkdebug::$TEST_IMG.data" "$TEST_IMG"
+$QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n -C "$TEST_IMG.src" "$TEST_IMG"
+$QEMU_IMG compare -f $IMGFMT -F $IMGFMT "$TEST_IMG.src" "$TEST_IMG"
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/244.out b/tests/qemu-iotests/244.out
index 6a3d0067cc..e6f4dc7993 100644
--- a/tests/qemu-iotests/244.out
+++ b/tests/qemu-iotests/244.out
@@ -122,4 +122,10 @@ Offset          Length          Mapped to       File
 0               0x100000        0               TEST_DIR/t.qcow2.data
 [{ "start": 0, "length": 1048576, "depth": 0, "zero": false, "data": true, "offset": 0},
 { "start": 1048576, "length": 66060288, "depth": 0, "zero": true, "data": false}]
+
+=== Copy offloading ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IMGFMT.data
+Images are identical.
+Images are identical.
 *** done
diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 0473e824ed..8815052eb5 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -714,6 +714,65 @@ class VM(qtest.QEMUQtestMachine):
 
         return fields.items() <= ret.items()
 
+    def assert_block_path(self, root, path, expected_node, graph=None):
+        """
+        Check whether the node under the given path in the block graph
+        is @expected_node.
+
+        @root is the node name of the node where the @path is rooted.
+
+        @path is a string that consists of child names separated by
+        slashes.  It must begin with a slash.
+
+        Examples for @root + @path:
+          - root="qcow2-node", path="/backing/file"
+          - root="quorum-node", path="/children.2/file"
+
+        Hypothetically, @path could be empty, in which case it would
+        point to @root.  However, in practice this case is not useful
+        and hence not allowed.
+
+        @expected_node may be None.  (All elements of the path but the
+        leaf must still exist.)
+
+        @graph may be None or the result of an x-debug-query-block-graph
+        call that has already been performed.
+        """
+        if graph is None:
+            graph = self.qmp('x-debug-query-block-graph')['return']
+
+        iter_path = iter(path.split('/'))
+
+        # Must start with a /
+        assert next(iter_path) == ''
+
+        node = next((node for node in graph['nodes'] if node['name'] == root),
+                    None)
+
+        # An empty @path is not allowed, so the root node must be present
+        assert node is not None, 'Root node %s not found' % root
+
+        for child_name in iter_path:
+            assert node is not None, 'Cannot follow path %s%s' % (root, path)
+
+            try:
+                node_id = next(edge['child'] for edge in graph['edges'] \
+                                             if edge['parent'] == node['id'] and
+                                                edge['name'] == child_name)
+
+                node = next(node for node in graph['nodes'] \
+                                 if node['id'] == node_id)
+            except StopIteration:
+                node = None
+
+        if node is None:
+            assert expected_node is None, \
+                   'No node found under %s (but expected %s)' % \
+                   (path, expected_node)
+        else:
+            assert node['name'] == expected_node, \
+                   'Found node %s under %s (but expected %s)' % \
+                   (node['name'], path, expected_node)
 
 index_re = re.compile(r'([^\[]+)\[([^\]]+)\]')