iotests: Test cancelling a job and closing the VM

This patch adds a test where we cancel a throttled mirror job and
immediately close the VM before it can be cancelled.  Doing so will
invoke bdrv_drain_all() while the mirror job tries to drain the
throttled node.  When bdrv_drain_all_end() tries to lift its drain on
the throttle node, the job will exit and replace the current root node
of the BB drive0 (which is the job's filter node) by the throttle node.
Before the previous patch, this replacement did not increase drive0's
quiesce_counter by a sufficient amount, so when
bdrv_parent_drained_end() (invoked by bdrv_do_drained_end(), invoked by
bdrv_drain_all_end()) tried to end the drain on all of the throttle
node's parents, it decreased drive0's quiesce_counter below 0 -- which
fails an assertion.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/tests/qemu-iotests/255 b/tests/qemu-iotests/255
index c0bb37a..49433ec 100755
--- a/tests/qemu-iotests/255
+++ b/tests/qemu-iotests/255
@@ -35,6 +35,10 @@ def blockdev_create(vm, options):
         vm.run_job('job0')
     iotests.log("")
 
+iotests.log('Finishing a commit job with background reads')
+iotests.log('============================================')
+iotests.log('')
+
 with iotests.FilePath('t.qcow2') as disk_path, \
      iotests.FilePath('t.qcow2.mid') as mid_path, \
      iotests.FilePath('t.qcow2.base') as base_path, \
@@ -81,3 +85,51 @@ with iotests.FilePath('t.qcow2') as disk_path, \
                 auto_dismiss=True)
 
     vm.shutdown()
+
+iotests.log('')
+iotests.log('Closing the VM while a job is being cancelled')
+iotests.log('=============================================')
+iotests.log('')
+
+with iotests.FilePath('src.qcow2') as src_path, \
+     iotests.FilePath('dst.qcow2') as dst_path, \
+     iotests.VM() as vm:
+
+    iotests.log('=== Create images and start VM ===')
+    iotests.log('')
+
+    size = 128 * 1024 * 1024
+    size_str = str(size)
+
+    iotests.qemu_img_log('create', '-f', iotests.imgfmt, src_path, size_str)
+    iotests.qemu_img_log('create', '-f', iotests.imgfmt, dst_path, size_str)
+
+    iotests.log(iotests.qemu_io('-f', iotests.imgfmt, '-c', 'write 0 1M',
+                                src_path),
+                filters=[iotests.filter_test_dir, iotests.filter_qemu_io])
+
+    vm.add_object('throttle-group,x-bps-read=4096,id=throttle0')
+
+    vm.add_blockdev('file,node-name=src-file,filename=%s' % (src_path))
+    vm.add_blockdev('%s,node-name=src,file=src-file' % (iotests.imgfmt))
+
+    vm.add_blockdev('file,node-name=dst-file,filename=%s' % (dst_path))
+    vm.add_blockdev('%s,node-name=dst,file=dst-file' % (iotests.imgfmt))
+
+    vm.add_blockdev('throttle,node-name=src-throttled,' +
+                    'throttle-group=throttle0,file=src')
+
+    vm.add_device('virtio-blk,drive=src-throttled')
+
+    vm.launch()
+
+    iotests.log('=== Start a mirror job ===')
+    iotests.log('')
+
+    vm.qmp_log('blockdev-mirror', job_id='job0', device='src-throttled',
+                                  target='dst', sync='full')
+
+    vm.qmp_log('block-job-cancel', device='job0')
+    vm.qmp_log('quit')
+
+    vm.shutdown()