Re: [PATCH v4 4/4] iotests: Test node/bitmap aliases during migration

[Eric Blake]

On 8/18/20 8:32 AM, Max Reitz wrote:
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   tests/qemu-iotests/300     | 595 +++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/300.out |   5 +

Rather sparse output (I hate debugging those sorts of outputs when the 
test is failing).

>   tests/qemu-iotests/group   |   1 +
>   3 files changed, 601 insertions(+)
>   create mode 100755 tests/qemu-iotests/300
>   create mode 100644 tests/qemu-iotests/300.out

> +        # Dirty some random megabytes
> +        for _ in range(9):
> +            mb_ofs = random.randrange(1024)
> +            self.vm_a.hmp_qemu_io(self.src_node_name, f'write {mb_ofs}M 1M')

It turns out that the discard operation likewise dirties the bitmap, but 
slightly faster (see edb90bbd).  We could optimize it on top, but I'm 
not going to require a micro-optimizing to get it in.  The test takes 
about 12 seconds to run for me, but you didn't mark it as such in 
'group', so that's good; but it turns up a problem:

300      fail       [20:55:54] [20:56:06]                    output 
mismatch (see 300.out.bad)
--- /home/eblake/qemu-tmp2/tests/qemu-iotests/300.out	2020-08-19 
20:53:11.087791988 -0500
+++ /home/eblake/qemu-tmp2/tests/qemu-iotests/300.out.bad	2020-08-19 
20:56:06.092428756 -0500
@@ -1,5 +1,41 @@
-.....................................
+WARNING:qemu.machine:qemu received signal 11; command: 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../x86_64-softmmu/qemu-system-x86_64 
-display none -vga none -chardev 
socket,id=mon,path=/tmp/tmp.qT831UThme/qemu-b-798452-monitor.sock -mon 
chardev=mon,mode=control -qtest 
unix:path=/tmp/tmp.qT831UThme/qemu-b-798452-qtest.sock -accel qtest 
-nodefaults -display none -accel qtest -blockdev 
node-name=node0,driver=null-co -incoming unix:/tmp/tmp.qT831UThme/mig_sock"
+.............FE.......................
+======================================================================
+ERROR: test_migratee_bitmap_is_not_mapped_on_dst 
(__main__.TestBlockBitmapMappingErrors)
+----------------------------------------------------------------------
+Traceback (most recent call last):
+  File 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../python/qemu/machine.py", 
line 435, in _do_shutdown
+    self._soft_shutdown(timeout, has_quit)
+  File 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../python/qemu/machine.py", 
line 415, in _soft_shutdown
+    self._qmp.cmd('quit')
+  File 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../python/qemu/qmp.py", 
line 266, in cmd
+    return self.cmd_obj(qmp_cmd)
+  File 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../python/qemu/qmp.py", 
line 246, in cmd_obj
+    self.__sock.sendall(json.dumps(qmp_cmd).encode('utf-8'))
+BrokenPipeError: [Errno 32] Broken pipe
+
+The above exception was the direct cause of the following exception:
+
+Traceback (most recent call last):
+  File "300", line 76, in tearDown
+    self.vm_b.shutdown()
+  File 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../python/qemu/machine.py", 
line 465, in shutdown
+    self._do_shutdown(timeout, has_quit)
+  File 
"/home/eblake/qemu-tmp2/tests/qemu-iotests/../../python/qemu/machine.py", 
line 438, in _do_shutdown
+    raise AbnormalShutdown("Could not perform graceful shutdown") \
+qemu.machine.AbnormalShutdown: Could not perform graceful shutdown
+
+======================================================================
+FAIL: test_migratee_bitmap_is_not_mapped_on_dst 
(__main__.TestBlockBitmapMappingErrors)
+----------------------------------------------------------------------
+Traceback (most recent call last):
+  File "300", line 384, in test_migratee_bitmap_is_not_mapped_on_dst
+    self.migrate(False)
+  File "300", line 99, in migrate
+    self.assertEqual(self.vm_a.wait_migration('postmigrate'),
+AssertionError: False != True
+
 ----------------------------------------------------------------------
 Ran 37 tests

-OK
+FAILED (failures=1, errors=1)

I'm not sure why I'm seeing that, but it looks like you've got a bad 
deref somewhere in the alias code.

> +class TestLongBitmapNames(TestAliasMigration):
> +    # Giving long bitmap names is OK, as long as there is a short alias for
> +    # migration
> +    src_bmap_name = 'a' * 512
> +    dst_bmap_name = 'b' * 512

This part's new compared to v3 ;)  Looks like you've made several 
enhancements.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org