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

Block layer patches:

- block: Fix forbidden use of polling in drained_end
- block: Don't wait for I/O throttling while exiting QEMU
- iotests: Use read-zeroes for the null driver to be Valgrind-friendly

# gpg: Signature made Fri 19 Jul 2019 14:30:14 BST
# 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:
  iotests: Test quitting with job on throttled node
  vl: Drain before (block) job cancel when quitting
  iotests: Test commit with a filter on the chain
  iotests: Add @has_quit to vm.shutdown()
  block: Loop unsafely in bdrv*drained_end()
  tests: Extend commit by drained_end test
  block: Do not poll in bdrv_do_drained_end()
  tests: Lock AioContexts in test-block-iothread
  block: Make bdrv_parent_drained_[^_]*() static
  block: Add @drained_end_counter
  tests: Add job commit by drained_end test
  block: Introduce BdrvChild.parent_quiesce_counter
  iotests: Set read-zeroes on in null block driver for Valgrind

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

17 files changed, 383 insertions, 129 deletions

diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
index b81133a474..aa0b1847e3 100755
--- a/tests/qemu-iotests/040
+++ b/tests/qemu-iotests/040
@@ -92,9 +92,10 @@ class TestSingleDrive(ImageCommitTestCase):
 
         self.vm.add_device("scsi-hd,id=scsi0,drive=drive0")
         self.vm.launch()
+        self.has_quit = False
 
     def tearDown(self):
-        self.vm.shutdown()
+        self.vm.shutdown(has_quit=self.has_quit)
         os.remove(test_img)
         os.remove(mid_img)
         os.remove(backing_img)
@@ -109,6 +110,43 @@ class TestSingleDrive(ImageCommitTestCase):
         self.assertEqual(-1, qemu_io('-f', 'raw', '-c', 'read -P 0xab 0 524288', backing_img).find("verification failed"))
         self.assertEqual(-1, qemu_io('-f', 'raw', '-c', 'read -P 0xef 524288 524288', backing_img).find("verification failed"))
 
+    def test_commit_with_filter_and_quit(self):
+        result = self.vm.qmp('object-add', qom_type='throttle-group', id='tg')
+        self.assert_qmp(result, 'return', {})
+
+        # Add a filter outside of the backing chain
+        result = self.vm.qmp('blockdev-add', driver='throttle', node_name='filter', throttle_group='tg', file='mid')
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('block-commit', device='drive0')
+        self.assert_qmp(result, 'return', {})
+
+        # Quit immediately, thus forcing a simultaneous cancel of the
+        # block job and a bdrv_drain_all()
+        result = self.vm.qmp('quit')
+        self.assert_qmp(result, 'return', {})
+
+        self.has_quit = True
+
+    # Same as above, but this time we add the filter after starting the job
+    def test_commit_plus_filter_and_quit(self):
+        result = self.vm.qmp('object-add', qom_type='throttle-group', id='tg')
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('block-commit', device='drive0')
+        self.assert_qmp(result, 'return', {})
+
+        # Add a filter outside of the backing chain
+        result = self.vm.qmp('blockdev-add', driver='throttle', node_name='filter', throttle_group='tg', file='mid')
+        self.assert_qmp(result, 'return', {})
+
+        # Quit immediately, thus forcing a simultaneous cancel of the
+        # block job and a bdrv_drain_all()
+        result = self.vm.qmp('quit')
+        self.assert_qmp(result, 'return', {})
+
+        self.has_quit = True
+
     def test_device_not_found(self):
         result = self.vm.qmp('block-commit', device='nonexistent', top='%s' % mid_img)
         self.assert_qmp(result, 'error/class', 'DeviceNotFound')
diff --git a/tests/qemu-iotests/040.out b/tests/qemu-iotests/040.out
index 802ffaa0c0..220a5fa82c 100644
--- a/tests/qemu-iotests/040.out
+++ b/tests/qemu-iotests/040.out
@@ -1,5 +1,5 @@
-...........................................
+...............................................
 ----------------------------------------------------------------------
-Ran 43 tests
+Ran 47 tests
 
 OK
diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index 200660f977..ce942a5444 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -251,11 +251,11 @@ echo
 # Cannot use the test image because cache=none might not work on the host FS
 # Use cdrom so that we won't get errors about missing media
 
-run_qemu -drive driver=null-co,cache=none
-run_qemu -drive driver=null-co,cache=directsync
-run_qemu -drive driver=null-co,cache=writeback
-run_qemu -drive driver=null-co,cache=writethrough
-run_qemu -drive driver=null-co,cache=unsafe
+run_qemu -drive driver=null-co,read-zeroes=on,cache=none
+run_qemu -drive driver=null-co,read-zeroes=on,cache=directsync
+run_qemu -drive driver=null-co,read-zeroes=on,cache=writeback
+run_qemu -drive driver=null-co,read-zeroes=on,cache=writethrough
+run_qemu -drive driver=null-co,read-zeroes=on,cache=unsafe
 run_qemu -drive driver=null-co,cache=invalid_value
 
 # Can't test direct=on here because O_DIRECT might not be supported on this FS
diff --git a/tests/qemu-iotests/051.pc.out b/tests/qemu-iotests/051.pc.out
index 2d811c166c..000557c7c8 100644
--- a/tests/qemu-iotests/051.pc.out
+++ b/tests/qemu-iotests/051.pc.out
@@ -245,23 +245,23 @@ QEMU X.Y.Z monitor - type 'help' for more information
 
 === Cache modes ===
 
-Testing: -drive driver=null-co,cache=none
+Testing: -drive driver=null-co,read-zeroes=on,cache=none
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) quit
 
-Testing: -drive driver=null-co,cache=directsync
+Testing: -drive driver=null-co,read-zeroes=on,cache=directsync
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) quit
 
-Testing: -drive driver=null-co,cache=writeback
+Testing: -drive driver=null-co,read-zeroes=on,cache=writeback
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) quit
 
-Testing: -drive driver=null-co,cache=writethrough
+Testing: -drive driver=null-co,read-zeroes=on,cache=writethrough
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) quit
 
-Testing: -drive driver=null-co,cache=unsafe
+Testing: -drive driver=null-co,read-zeroes=on,cache=unsafe
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) quit
 
diff --git a/tests/qemu-iotests/093 b/tests/qemu-iotests/093
index d88fbc182e..4b2cac1d0c 100755
--- a/tests/qemu-iotests/093
+++ b/tests/qemu-iotests/093
@@ -38,7 +38,7 @@ class ThrottleTestCase(iotests.QMPTestCase):
     def setUp(self):
         self.vm = iotests.VM()
         for i in range(0, self.max_drives):
-            self.vm.add_drive(self.test_img)
+            self.vm.add_drive(self.test_img, "file.read-zeroes=on")
         self.vm.launch()
 
     def tearDown(self):
@@ -273,7 +273,8 @@ class ThrottleTestGroupNames(iotests.QMPTestCase):
     def setUp(self):
         self.vm = iotests.VM()
         for i in range(0, self.max_drives):
-            self.vm.add_drive(self.test_img, "throttling.iops-total=100")
+            self.vm.add_drive(self.test_img,
+                              "throttling.iops-total=100,file.read-zeroes=on")
         self.vm.launch()
 
     def tearDown(self):
@@ -378,10 +379,10 @@ class ThrottleTestRemovableMedia(iotests.QMPTestCase):
     def test_removable_media(self):
         # Add a couple of dummy nodes named cd0 and cd1
         result = self.vm.qmp("blockdev-add", driver="null-aio",
-                             node_name="cd0")
+                             read_zeroes=True, node_name="cd0")
         self.assert_qmp(result, 'return', {})
         result = self.vm.qmp("blockdev-add", driver="null-aio",
-                             node_name="cd1")
+                             read_zeroes=True, node_name="cd1")
         self.assert_qmp(result, 'return', {})
 
         # Attach a CD drive with cd0 inserted
diff --git a/tests/qemu-iotests/136 b/tests/qemu-iotests/136
index af7ffa4540..a46a7b7630 100755
--- a/tests/qemu-iotests/136
+++ b/tests/qemu-iotests/136
@@ -74,6 +74,7 @@ sector = "%d"
                           (self.account_invalid and "on" or "off"))
         drive_args.append("stats-account-failed=%s" %
                           (self.account_failed and "on" or "off"))
+        drive_args.append("file.image.read-zeroes=on")
         self.create_blkdebug_file()
         self.vm = iotests.VM().add_drive('blkdebug:%s:%s' %
                                          (blkdebug_file, self.test_img),
diff --git a/tests/qemu-iotests/186 b/tests/qemu-iotests/186
index 7e7d45babc..5f6b18c150 100755
--- a/tests/qemu-iotests/186
+++ b/tests/qemu-iotests/186
@@ -86,8 +86,8 @@ echo "=== -blockdev/-device=<node-name> ==="
 echo
 
 for dev in $fixed $removable; do
-    check_info_block -blockdev driver=null-co,node-name=null -device $dev,drive=null
-    check_info_block -blockdev driver=null-co,node-name=null -device $dev,drive=null,id=qdev_id
+    check_info_block -blockdev driver=null-co,read-zeroes=on,node-name=null -device $dev,drive=null
+    check_info_block -blockdev driver=null-co,read-zeroes=on,node-name=null -device $dev,drive=null,id=qdev_id
 done
 
 echo
@@ -97,7 +97,7 @@ echo
 # This creates two BlockBackends that will show up in 'info block'!
 # A monitor-owned one from -drive, and anonymous one from -device
 for dev in $fixed $removable; do
-    check_info_block -drive if=none,driver=null-co,node-name=null -device $dev,drive=null,id=qdev_id
+    check_info_block -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device $dev,drive=null,id=qdev_id
 done
 
 echo
@@ -105,8 +105,8 @@ echo "=== -drive if=none/-device=<bb-name> (with medium) ==="
 echo
 
 for dev in $fixed $removable; do
-    check_info_block -drive if=none,driver=null-co,node-name=null -device $dev,drive=none0
-    check_info_block -drive if=none,driver=null-co,node-name=null -device $dev,drive=none0,id=qdev_id
+    check_info_block -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device $dev,drive=none0
+    check_info_block -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device $dev,drive=none0,id=qdev_id
 done
 
 echo
@@ -125,15 +125,15 @@ echo "=== -drive if=... ==="
 echo
 
 check_info_block -drive if=floppy
-check_info_block -drive if=floppy,driver=null-co
+check_info_block -drive if=floppy,driver=null-co,read-zeroes=on
 
-check_info_block -drive if=ide,driver=null-co
+check_info_block -drive if=ide,driver=null-co,read-zeroes=on
 check_info_block -drive if=ide,media=cdrom
-check_info_block -drive if=ide,driver=null-co,media=cdrom
+check_info_block -drive if=ide,driver=null-co,read-zeroes=on,media=cdrom
 
-check_info_block -drive if=virtio,driver=null-co
+check_info_block -drive if=virtio,driver=null-co,read-zeroes=on
 
-check_info_block -drive if=pflash,driver=null-co,size=1M
+check_info_block -drive if=pflash,driver=null-co,read-zeroes=on,size=1M
 
 # success, all done
 echo "*** done"
diff --git a/tests/qemu-iotests/186.out b/tests/qemu-iotests/186.out
index 716b01ac3d..5b3504042a 100644
--- a/tests/qemu-iotests/186.out
+++ b/tests/qemu-iotests/186.out
@@ -54,103 +54,103 @@ qdev_id: [not inserted]
 
 === -blockdev/-device=<node-name> ===
 
-Testing: -blockdev driver=null-co,node-name=null -device ide-hd,drive=null
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device ide-hd,drive=null,id=qdev_id
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device scsi-hd,drive=null
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device scsi-hd,drive=null,id=qdev_id
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device virtio-blk-pci,drive=null
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device virtio-blk-pci,drive=null,id=qdev_id
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device floppy,drive=null
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device floppy,drive=null,id=qdev_id
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device ide-cd,drive=null
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device ide-cd,drive=null,id=qdev_id
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device scsi-cd,drive=null
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -blockdev driver=null-co,node-name=null -device scsi-cd,drive=null,id=qdev_id
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: null-co:// (null-co)
+null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -159,76 +159,76 @@ null: null-co:// (null-co)
 
 === -drive if=none/-device=<node-name> ===
 
-Testing: -drive if=none,driver=null-co,node-name=null -device ide-hd,drive=null,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: null-co:// (null-co)
+null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device scsi-hd,drive=null,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: null-co:// (null-co)
+null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device virtio-blk-pci,drive=null,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: null-co:// (null-co)
+null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device floppy,drive=null,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: null-co:// (null-co)
+null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device ide-cd,drive=null,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: null-co:// (null-co)
+null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device scsi-cd,drive=null,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: null-co:// (null-co)
+null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -237,103 +237,103 @@ null: null-co:// (null-co)
 
 === -drive if=none/-device=<bb-name> (with medium) ===
 
-Testing: -drive if=none,driver=null-co,node-name=null -device ide-hd,drive=none0
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=none0
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device ide-hd,drive=none0,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=none0,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device scsi-hd,drive=none0
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=none0
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device scsi-hd,drive=none0,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=none0,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device virtio-blk-pci,drive=none0
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=none0
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device virtio-blk-pci,drive=none0,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=none0,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device floppy,drive=none0
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=none0
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device floppy,drive=none0,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=none0,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device ide-cd,drive=none0
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=none0
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device ide-cd,drive=none0,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=none0,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device scsi-cd,drive=none0
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=none0
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=none,driver=null-co,node-name=null -device scsi-cd,drive=none0,id=qdev_id
+Testing: -drive if=none,driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=none0,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-none0 (null): null-co:// (null-co)
+none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -408,19 +408,19 @@ floppy0: [not inserted]
     Removable device: not locked, tray closed
 (qemu) quit
 
-Testing: -drive if=floppy,driver=null-co
+Testing: -drive if=floppy,driver=null-co,read-zeroes=on
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-floppy0 (NODE_NAME): null-co:// (null-co)
+floppy0 (NODE_NAME): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=ide,driver=null-co
+Testing: -drive if=ide,driver=null-co,read-zeroes=on
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-ide0-hd0 (NODE_NAME): null-co:// (null-co)
+ide0-hd0 (NODE_NAME): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
@@ -433,27 +433,27 @@ ide0-cd0: [not inserted]
     Removable device: not locked, tray closed
 (qemu) quit
 
-Testing: -drive if=ide,driver=null-co,media=cdrom
+Testing: -drive if=ide,driver=null-co,read-zeroes=on,media=cdrom
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-ide0-cd0 (NODE_NAME): null-co:// (null-co, read-only)
+ide0-cd0 (NODE_NAME): json:{"read-zeroes": "on", "driver": "null-co"} (null-co, read-only)
     Attached to:      PATH
     Removable device: not locked, tray closed
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=virtio,driver=null-co
+Testing: -drive if=virtio,driver=null-co,read-zeroes=on
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-virtio0 (NODE_NAME): null-co:// (null-co)
+virtio0 (NODE_NAME): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
 
-Testing: -drive if=pflash,driver=null-co,size=1M
+Testing: -drive if=pflash,driver=null-co,read-zeroes=on,size=1M
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-pflash0 (NODE_NAME): json:{"driver": "null-co", "size": "1M"} (null-co)
+pflash0 (NODE_NAME): json:{"read-zeroes": "on", "driver": "null-co", "size": "1M"} (null-co)
     Attached to:      PATH
     Cache mode:       writeback
 (qemu) quit
diff --git a/tests/qemu-iotests/218 b/tests/qemu-iotests/218
index 92c331b6fb..2554d84581 100755
--- a/tests/qemu-iotests/218
+++ b/tests/qemu-iotests/218
@@ -27,9 +27,9 @@
 # Creator/Owner: Max Reitz <mreitz@redhat.com>
 
 import iotests
-from iotests import log
+from iotests import log, qemu_img, qemu_io_silent
 
-iotests.verify_platform(['linux'])
+iotests.verify_image_format(supported_fmts=['qcow2', 'raw'])
 
 
 # Launches the VM, adds two null-co nodes (source and target), and
@@ -136,3 +136,54 @@ with iotests.VM() as vm:
 
     log(vm.event_wait('BLOCK_JOB_CANCELLED'),
         filters=[iotests.filter_qmp_event])
+
+log('')
+log('=== Cancel mirror job from throttled node by quitting ===')
+log('')
+
+with iotests.VM() as vm, \
+     iotests.FilePath('src.img') as src_img_path:
+
+    assert qemu_img('create', '-f', iotests.imgfmt, src_img_path, '64M') == 0
+    assert qemu_io_silent('-f', iotests.imgfmt, src_img_path,
+                          '-c', 'write -P 42 0M 64M') == 0
+
+    vm.launch()
+
+    ret = vm.qmp('object-add', qom_type='throttle-group', id='tg',
+                 props={'x-bps-read': 4096})
+    assert ret['return'] == {}
+
+    ret = vm.qmp('blockdev-add',
+                 node_name='source',
+                 driver=iotests.imgfmt,
+                 file={
+                     'driver': 'file',
+                     'filename': src_img_path
+                 })
+    assert ret['return'] == {}
+
+    ret = vm.qmp('blockdev-add',
+                 node_name='throttled-source',
+                 driver='throttle',
+                 throttle_group='tg',
+                 file='source')
+    assert ret['return'] == {}
+
+    ret = vm.qmp('blockdev-add',
+                 node_name='target',
+                 driver='null-co',
+                 size=(64 * 1048576))
+    assert ret['return'] == {}
+
+    ret = vm.qmp('blockdev-mirror',
+                 job_id='mirror',
+                 device='throttled-source',
+                 target='target',
+                 sync='full')
+    assert ret['return'] == {}
+
+    log(vm.qmp('quit'))
+
+    with iotests.Timeout(5, 'Timeout waiting for VM to quit'):
+        vm.shutdown(has_quit=True)
diff --git a/tests/qemu-iotests/218.out b/tests/qemu-iotests/218.out
index 825a657081..5a86a97550 100644
--- a/tests/qemu-iotests/218.out
+++ b/tests/qemu-iotests/218.out
@@ -28,3 +28,7 @@ Cancelling job
 Cancelling job
 {"return": {}}
 {"data": {"device": "mirror", "len": 1048576, "offset": 1048576, "speed": 0, "type": "mirror"}, "event": "BLOCK_JOB_CANCELLED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+
+=== Cancel mirror job from throttled node by quitting ===
+
+{"return": {}}
diff --git a/tests/qemu-iotests/227 b/tests/qemu-iotests/227
index bdd727a721..637d7c3726 100755
--- a/tests/qemu-iotests/227
+++ b/tests/qemu-iotests/227
@@ -57,7 +57,7 @@ echo
 echo '=== blockstats with -drive if=virtio ==='
 echo
 
-run_qemu -drive driver=null-co,if=virtio <<EOF
+run_qemu -drive driver=null-co,read-zeroes=on,if=virtio <<EOF
 { "execute": "qmp_capabilities" }
 { "execute": "query-blockstats"}
 { "execute": "quit" }
@@ -87,7 +87,7 @@ echo
 echo '=== blockstats with -blockdev and -device ==='
 echo
 
-run_qemu -blockdev driver=null-co,node-name=null -device virtio-blk,drive=null,id=virtio0 <<EOF
+run_qemu -blockdev driver=null-co,read-zeroes=on,node-name=null -device virtio-blk,drive=null,id=virtio0 <<EOF
 { "execute": "qmp_capabilities" }
 { "execute": "query-blockstats"}
 { "execute": "quit" }
diff --git a/tests/qemu-iotests/227.out b/tests/qemu-iotests/227.out
index e77efaf4cf..3dd3ca5708 100644
--- a/tests/qemu-iotests/227.out
+++ b/tests/qemu-iotests/227.out
@@ -2,7 +2,7 @@ QA output created by 227
 
 === blockstats with -drive if=virtio ===
 
-Testing: -drive driver=null-co,if=virtio
+Testing: -drive driver=null-co,read-zeroes=on,if=virtio
 {
     QMP_VERSION
 }
@@ -150,7 +150,7 @@ Testing: -blockdev driver=null-co,node-name=null
 
 === blockstats with -blockdev and -device ===
 
-Testing: -blockdev driver=null-co,node-name=null -device virtio-blk,drive=null,id=virtio0
+Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device virtio-blk,drive=null,id=virtio0
 {
     QMP_VERSION
 }
diff --git a/tests/qemu-iotests/238 b/tests/qemu-iotests/238
index 1c0a46fa90..08bc7e6b4b 100755
--- a/tests/qemu-iotests/238
+++ b/tests/qemu-iotests/238
@@ -31,7 +31,7 @@ else:
 vm = iotests.VM()
 vm.launch()
 
-log(vm.qmp('blockdev-add', node_name='hd0', driver='null-co'))
+log(vm.qmp('blockdev-add', node_name='hd0', driver='null-co', read_zeroes=True))
 log(vm.qmp('object-add', qom_type='iothread', id='iothread0'))
 log(vm.qmp('device_add', id='scsi0', driver=virtio_scsi_device, iothread='iothread0'))
 log(vm.qmp('device_add', id='scsi-hd0', driver='scsi-hd', drive='hd0'))
diff --git a/tests/qemu-iotests/240 b/tests/qemu-iotests/240
index 5be6b9c0f7..f73bc07d80 100755
--- a/tests/qemu-iotests/240
+++ b/tests/qemu-iotests/240
@@ -76,7 +76,7 @@ echo
 
 run_qemu <<EOF
 { "execute": "qmp_capabilities" }
-{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "hd0"}}
+{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "read-zeroes": true, "node-name": "hd0"}}
 { "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread0"}}
 { "execute": "device_add", "arguments": {"id": "scsi0", "driver": "${virtio_scsi}", "iothread": "iothread0"}}
 { "execute": "device_add", "arguments": {"id": "scsi-hd0", "driver": "scsi-hd", "drive": "hd0"}}
@@ -94,7 +94,7 @@ echo
 
 run_qemu <<EOF
 { "execute": "qmp_capabilities" }
-{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "hd0", "read-only": true}}
+{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "read-zeroes": true, "node-name": "hd0", "read-only": true}}
 { "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread0"}}
 { "execute": "device_add", "arguments": {"id": "scsi0", "driver": "${virtio_scsi}", "iothread": "iothread0"}}
 { "execute": "device_add", "arguments": {"id": "scsi-hd0", "driver": "scsi-hd", "drive": "hd0"}}
@@ -112,7 +112,7 @@ echo
 
 run_qemu <<EOF
 { "execute": "qmp_capabilities" }
-{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "hd0", "read-only": true}}
+{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "read-zeroes": true, "node-name": "hd0", "read-only": true}}
 { "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread0"}}
 { "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread1"}}
 { "execute": "device_add", "arguments": {"id": "scsi0", "driver": "${virtio_scsi}", "iothread": "iothread0"}}
@@ -134,7 +134,7 @@ echo
 
 run_qemu <<EOF
 { "execute": "qmp_capabilities" }
-{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "hd0", "read-only": true}}
+{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "read-zeroes": true, "node-name": "hd0", "read-only": true}}
 { "execute": "nbd-server-start", "arguments": {"addr":{"type":"unix","data":{"path":"$TEST_DIR/nbd"}}}}
 { "execute": "nbd-server-add", "arguments": {"device":"hd0"}}
 { "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread0"}}
diff --git a/tests/qemu-iotests/255 b/tests/qemu-iotests/255
index 49433ec122..3632d507d0 100755
--- a/tests/qemu-iotests/255
+++ b/tests/qemu-iotests/255
@@ -132,4 +132,4 @@ with iotests.FilePath('src.qcow2') as src_path, \
     vm.qmp_log('block-job-cancel', device='job0')
     vm.qmp_log('quit')
 
-    vm.shutdown()
+    vm.shutdown(has_quit=True)
diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c
index 12e2ecf517..03fa1142a1 100644
--- a/tests/test-bdrv-drain.c
+++ b/tests/test-bdrv-drain.c
@@ -1527,6 +1527,150 @@ static void test_set_aio_context(void)
     iothread_join(b);
 }
 
+
+typedef struct TestDropBackingBlockJob {
+    BlockJob common;
+    bool should_complete;
+    bool *did_complete;
+    BlockDriverState *detach_also;
+} TestDropBackingBlockJob;
+
+static int coroutine_fn test_drop_backing_job_run(Job *job, Error **errp)
+{
+    TestDropBackingBlockJob *s =
+        container_of(job, TestDropBackingBlockJob, common.job);
+
+    while (!s->should_complete) {
+        job_sleep_ns(job, 0);
+    }
+
+    return 0;
+}
+
+static void test_drop_backing_job_commit(Job *job)
+{
+    TestDropBackingBlockJob *s =
+        container_of(job, TestDropBackingBlockJob, common.job);
+
+    bdrv_set_backing_hd(blk_bs(s->common.blk), NULL, &error_abort);
+    bdrv_set_backing_hd(s->detach_also, NULL, &error_abort);
+
+    *s->did_complete = true;
+}
+
+static const BlockJobDriver test_drop_backing_job_driver = {
+    .job_driver = {
+        .instance_size  = sizeof(TestDropBackingBlockJob),
+        .free           = block_job_free,
+        .user_resume    = block_job_user_resume,
+        .drain          = block_job_drain,
+        .run            = test_drop_backing_job_run,
+        .commit         = test_drop_backing_job_commit,
+    }
+};
+
+/**
+ * Creates a child node with three parent nodes on it, and then runs a
+ * block job on the final one, parent-node-2.
+ *
+ * The job is then asked to complete before a section where the child
+ * is drained.
+ *
+ * Ending this section will undrain the child's parents, first
+ * parent-node-2, then parent-node-1, then parent-node-0 -- the parent
+ * list is in reverse order of how they were added.  Ending the drain
+ * on parent-node-2 will resume the job, thus completing it and
+ * scheduling job_exit().
+ *
+ * Ending the drain on parent-node-1 will poll the AioContext, which
+ * lets job_exit() and thus test_drop_backing_job_commit() run.  That
+ * function first removes the child as parent-node-2's backing file.
+ *
+ * In old (and buggy) implementations, there are two problems with
+ * that:
+ * (A) bdrv_drain_invoke() polls for every node that leaves the
+ *     drained section.  This means that job_exit() is scheduled
+ *     before the child has left the drained section.  Its
+ *     quiesce_counter is therefore still 1 when it is removed from
+ *     parent-node-2.
+ *
+ * (B) bdrv_replace_child_noperm() calls drained_end() on the old
+ *     child's parents as many times as the child is quiesced.  This
+ *     means it will call drained_end() on parent-node-2 once.
+ *     Because parent-node-2 is no longer quiesced at this point, this
+ *     will fail.
+ *
+ * bdrv_replace_child_noperm() therefore must call drained_end() on
+ * the parent only if it really is still drained because the child is
+ * drained.
+ *
+ * If removing child from parent-node-2 was successful (as it should
+ * be), test_drop_backing_job_commit() will then also remove the child
+ * from parent-node-0.
+ *
+ * With an old version of our drain infrastructure ((A) above), that
+ * resulted in the following flow:
+ *
+ * 1. child attempts to leave its drained section.  The call recurses
+ *    to its parents.
+ *
+ * 2. parent-node-2 leaves the drained section.  Polling in
+ *    bdrv_drain_invoke() will schedule job_exit().
+ *
+ * 3. parent-node-1 leaves the drained section.  Polling in
+ *    bdrv_drain_invoke() will run job_exit(), thus disconnecting
+ *    parent-node-0 from the child node.
+ *
+ * 4. bdrv_parent_drained_end() uses a QLIST_FOREACH_SAFE() loop to
+ *    iterate over the parents.  Thus, it now accesses the BdrvChild
+ *    object that used to connect parent-node-0 and the child node.
+ *    However, that object no longer exists, so it accesses a dangling
+ *    pointer.
+ *
+ * The solution is to only poll once when running a bdrv_drained_end()
+ * operation, specifically at the end when all drained_end()
+ * operations for all involved nodes have been scheduled.
+ * Note that this also solves (A) above, thus hiding (B).
+ */
+static void test_blockjob_commit_by_drained_end(void)
+{
+    BlockDriverState *bs_child, *bs_parents[3];
+    TestDropBackingBlockJob *job;
+    bool job_has_completed = false;
+    int i;
+
+    bs_child = bdrv_new_open_driver(&bdrv_test, "child-node", BDRV_O_RDWR,
+                                    &error_abort);
+
+    for (i = 0; i < 3; i++) {
+        char name[32];
+        snprintf(name, sizeof(name), "parent-node-%i", i);
+        bs_parents[i] = bdrv_new_open_driver(&bdrv_test, name, BDRV_O_RDWR,
+                                             &error_abort);
+        bdrv_set_backing_hd(bs_parents[i], bs_child, &error_abort);
+    }
+
+    job = block_job_create("job", &test_drop_backing_job_driver, NULL,
+                           bs_parents[2], 0, BLK_PERM_ALL, 0, 0, NULL, NULL,
+                           &error_abort);
+
+    job->detach_also = bs_parents[0];
+    job->did_complete = &job_has_completed;
+
+    job_start(&job->common.job);
+
+    job->should_complete = true;
+    bdrv_drained_begin(bs_child);
+    g_assert(!job_has_completed);
+    bdrv_drained_end(bs_child);
+    g_assert(job_has_completed);
+
+    bdrv_unref(bs_parents[0]);
+    bdrv_unref(bs_parents[1]);
+    bdrv_unref(bs_parents[2]);
+    bdrv_unref(bs_child);
+}
+
 int main(int argc, char **argv)
 {
     int ret;
@@ -1610,6 +1754,9 @@ int main(int argc, char **argv)
 
     g_test_add_func("/bdrv-drain/set_aio_context", test_set_aio_context);
 
+    g_test_add_func("/bdrv-drain/blockjob/commit_by_drained_end",
+                    test_blockjob_commit_by_drained_end);
+
     ret = g_test_run();
     qemu_event_destroy(&done_event);
     return ret;
diff --git a/tests/test-block-iothread.c b/tests/test-block-iothread.c
index 79d9cf8a57..1949d5e61a 100644
--- a/tests/test-block-iothread.c
+++ b/tests/test-block-iothread.c
@@ -348,8 +348,8 @@ static void test_sync_op(const void *opaque)
     if (t->blkfn) {
         t->blkfn(blk);
     }
-    aio_context_release(ctx);
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
+    aio_context_release(ctx);
 
     bdrv_unref(bs);
     blk_unref(blk);
@@ -476,6 +476,7 @@ static void test_propagate_basic(void)
 {
     IOThread *iothread = iothread_new();
     AioContext *ctx = iothread_get_aio_context(iothread);
+    AioContext *main_ctx;
     BlockBackend *blk;
     BlockDriverState *bs_a, *bs_b, *bs_verify;
     QDict *options;
@@ -504,12 +505,14 @@ static void test_propagate_basic(void)
     g_assert(bdrv_get_aio_context(bs_b) == ctx);
 
     /* Switch the AioContext back */
-    ctx = qemu_get_aio_context();
-    blk_set_aio_context(blk, ctx, &error_abort);
-    g_assert(blk_get_aio_context(blk) == ctx);
-    g_assert(bdrv_get_aio_context(bs_a) == ctx);
-    g_assert(bdrv_get_aio_context(bs_verify) == ctx);
-    g_assert(bdrv_get_aio_context(bs_b) == ctx);
+    main_ctx = qemu_get_aio_context();
+    aio_context_acquire(ctx);
+    blk_set_aio_context(blk, main_ctx, &error_abort);
+    aio_context_release(ctx);
+    g_assert(blk_get_aio_context(blk) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_a) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_verify) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_b) == main_ctx);
 
     bdrv_unref(bs_verify);
     bdrv_unref(bs_b);
@@ -534,6 +537,7 @@ static void test_propagate_diamond(void)
 {
     IOThread *iothread = iothread_new();
     AioContext *ctx = iothread_get_aio_context(iothread);
+    AioContext *main_ctx;
     BlockBackend *blk;
     BlockDriverState *bs_a, *bs_b, *bs_c, *bs_verify;
     QDict *options;
@@ -573,13 +577,15 @@ static void test_propagate_diamond(void)
     g_assert(bdrv_get_aio_context(bs_c) == ctx);
 
     /* Switch the AioContext back */
-    ctx = qemu_get_aio_context();
-    blk_set_aio_context(blk, ctx, &error_abort);
-    g_assert(blk_get_aio_context(blk) == ctx);
-    g_assert(bdrv_get_aio_context(bs_verify) == ctx);
-    g_assert(bdrv_get_aio_context(bs_a) == ctx);
-    g_assert(bdrv_get_aio_context(bs_b) == ctx);
-    g_assert(bdrv_get_aio_context(bs_c) == ctx);
+    main_ctx = qemu_get_aio_context();
+    aio_context_acquire(ctx);
+    blk_set_aio_context(blk, main_ctx, &error_abort);
+    aio_context_release(ctx);
+    g_assert(blk_get_aio_context(blk) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_verify) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_a) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_b) == main_ctx);
+    g_assert(bdrv_get_aio_context(bs_c) == main_ctx);
 
     blk_unref(blk);
     bdrv_unref(bs_verify);
@@ -685,7 +691,9 @@ static void test_attach_second_node(void)
     g_assert(bdrv_get_aio_context(bs) == ctx);
     g_assert(bdrv_get_aio_context(filter) == ctx);
 
+    aio_context_acquire(ctx);
     blk_set_aio_context(blk, main_ctx, &error_abort);
+    aio_context_release(ctx);
     g_assert(blk_get_aio_context(blk) == main_ctx);
     g_assert(bdrv_get_aio_context(bs) == main_ctx);
     g_assert(bdrv_get_aio_context(filter) == main_ctx);
@@ -712,7 +720,9 @@ static void test_attach_preserve_blk_ctx(void)
     g_assert(bdrv_get_aio_context(bs) == ctx);
 
     /* Remove the node again */
+    aio_context_acquire(ctx);
     blk_remove_bs(blk);
+    aio_context_release(ctx);
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(bs) == qemu_get_aio_context());
 
@@ -721,7 +731,9 @@ static void test_attach_preserve_blk_ctx(void)
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(bs) == ctx);
 
+    aio_context_acquire(ctx);
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
+    aio_context_release(ctx);
     bdrv_unref(bs);
     blk_unref(blk);
 }