On 11.12.20 14:10, Vladimir Sementsov-Ogievskiy wrote:
11.12.2020 15:49, Max Reitz wrote:
On 04.12.20 23:07, Vladimir Sementsov-Ogievskiy wrote:
From: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com>

The test case #310 is similar to #216 by Max Reitz. The difference is
that the test #310 involves a bottom node to the COR filter driver.

Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
  tests/qemu-iotests/310     | 114 +++++++++++++++++++++++++++++++++++++
  tests/qemu-iotests/310.out |  15 +++++
  tests/qemu-iotests/group   |   1 +
  3 files changed, 130 insertions(+)
  create mode 100755 tests/qemu-iotests/310
  create mode 100644 tests/qemu-iotests/310.out

diff --git a/tests/qemu-iotests/310 b/tests/qemu-iotests/310
new file mode 100755
index 0000000000..c8b34cd887
--- /dev/null
+++ b/tests/qemu-iotests/310
@@ -0,0 +1,114 @@
+#!/usr/bin/env python3
+#
+# Copy-on-read tests using a COR filter with a bottom node
+#
+# Copyright (C) 2018 Red Hat, Inc.
+# Copyright (c) 2020 Virtuozzo International GmbH
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import iotests
+from iotests import log, qemu_img, qemu_io_silent
+
+# Need backing file support
+iotests.script_initialize(supported_fmts=['qcow2', 'qcow', 'qed', 'vmdk'],
+                          supported_platforms=['linux'])
+
+log('')
+log('=== Copy-on-read across nodes ===')
+log('')
+
+# This test is similar to the 216 one by Max Reitz <mre...@redhat.com>
+# The difference is that this test case involves a bottom node to the
+# COR filter driver.
+
+with iotests.FilePath('base.img') as base_img_path, \
+     iotests.FilePath('mid.img') as mid_img_path, \
+     iotests.FilePath('top.img') as top_img_path, \
+     iotests.VM() as vm:
+
+    log('--- Setting up images ---')
+    log('')
+
+    assert qemu_img('create', '-f', iotests.imgfmt, base_img_path, '64M') == 0
+    assert qemu_io_silent(base_img_path, '-c', 'write -P 1 0M 1M') == 0
+    assert qemu_io_silent(base_img_path, '-c', 'write -P 1 3M 1M') == 0
+    assert qemu_img('create', '-f', iotests.imgfmt, '-b', base_img_path,
+                    '-F', iotests.imgfmt, mid_img_path) == 0
+    assert qemu_io_silent(mid_img_path,  '-c', 'write -P 3 2M 1M') == 0
+    assert qemu_io_silent(mid_img_path,  '-c', 'write -P 3 4M 1M') == 0
+    assert qemu_img('create', '-f', iotests.imgfmt, '-b', mid_img_path,
+                    '-F', iotests.imgfmt, top_img_path) == 0
+    assert qemu_io_silent(top_img_path,  '-c', 'write -P 2 1M 1M') == 0
+
+#      0 1 2 3 4
+# top    2
+# mid      3   3
+# base 1     1
+
+    log('Done')
+
+    log('')
+    log('--- Doing COR ---')
+    log('')
+
+    vm.launch()
+
+    log(vm.qmp('blockdev-add',
+               node_name='node0',
+               driver='copy-on-read',
+               bottom='node2',
+               file={
+                   'driver': iotests.imgfmt,
+                   'file': {
+                       'driver': 'file',
+                       'filename': top_img_path
+                   },
+                   'backing': {
+                       'node-name': 'node2',
+                       'driver': iotests.imgfmt,
+                       'file': {
+                           'driver': 'file',
+                           'filename': mid_img_path
+                       },
+                       'backing': {
+                           'driver': iotests.imgfmt,
+                           'file': {
+                               'driver': 'file',
+                               'filename': base_img_path
+                           }
+                       },
+                   }
+               }))
+
+    # Trigger COR
+    log(vm.qmp('human-monitor-command',
+               command_line='qemu-io node0 "read 0 5M"'))
+
+    vm.shutdown()
+
+    log('')
+    log('--- Checking COR result ---')
+    log('')
+
+    assert qemu_io_silent(base_img_path, '-c', 'discard 0 4M') == 0
+    assert qemu_io_silent(mid_img_path, '-c', 'discard 0M 5M') == 0

The data discard leaves behind is undefined, so this may not result in zeroes.  (In fact, the test does fail for me with vmdk, qed, and qcow.)  'write -z' would work better, although perhaps you intentionally chose discard to just drop the data from the backing images.

In that case, you could also recreate the middle image, so it’s empty then – the only problem with that is that it’ll break VMDK because it stores this reference to its backing image, and if the backing image is changed, you’ll get EINVAL when falling back to it...

(The same goes for overwriting any data in the backing image, though, be it with discard, write -z, or write -P 0.  So I suppose VMDK just won’t work with this test.)


I think the goal is just to be sure the following reads read from the top and check exactly that COR works.

So we can just use 'write -z'.. Or, we can changed the backing file of top_img to nothing instead. Can qemu-img do it?

Yes, with rebase -u -b ''. (I think I tested that, and that too didn’t work for all formats, though...?)

Max


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