[PATCH hci-8.0 3/5] iotests/nbd-commands: exercise the simple and structured reply modes #VSTOR-119829

["Denis V. Lunev" <den@openvz.org>]

From: Denis V. Lunev <den@openvz.org>

Every NBD request the iotests send arrives in NBD_MODE_EXTENDED, so
the server paths kept for older clients are never taken. Instrumenting
nbd_co_receive_request() over the whole auto group and every test that
touches NBD gives mode 4 for all of them, which leaves
nbd_co_send_simple_reply() and the compact header handling dead under
test. A regression there would only show against a third party client.

libnbd can negotiate down, so run the same command set three times,
once per mode, and assert the mode that was actually reached. Block
status is limited to the two modes that can negotiate a meta context.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
Message-ID: <20260827161002.310688-4-den@openvz.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 tests/qemu-iotests/tests/nbd-commands     | 29 +++++++++++++++++++++++
 tests/qemu-iotests/tests/nbd-commands.out |  4 ++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/tests/nbd-commands b/tests/qemu-iotests/tests/nbd-commands
index cbfc47782ff..3dfe9131900 100755
--- a/tests/qemu-iotests/tests/nbd-commands
+++ b/tests/qemu-iotests/tests/nbd-commands
@@ -119,6 +119,35 @@ class TestNbdCommands(iotests.QMPTestCase):
         self.assertEqual(self.top_extents(), [(0, size, 0)])
         qemu_io('-c', f'read -P {pattern} 0 {size}', top)
 
+    def check_commands(self, structured, extended):
+        self.connect(structured, extended)
+
+        self.assertEqual(self.h.pread(4096, 4096), bytes([pattern]) * 4096)
+
+        self.h.cache(size, 0)
+
+        self.h.pwrite(b'x' * 4096, 4096)
+        self.h.flush()
+        self.assertEqual(self.h.pread(4096, 4096), b'x' * 4096)
+
+        self.h.zero(4096, 8192)
+        self.assertEqual(self.h.pread(4096, 8192), bytes(4096))
+
+        self.h.trim(4096, 16384)
+
+        if structured:
+            self.assertEqual(self.block_status()['qemu:allocation-depth'],
+                             [(size, DEPTH_LOCAL)])
+
+    def test_commands_simple_replies(self):
+        self.check_commands(structured=False, extended=False)
+
+    def test_commands_structured_replies(self):
+        self.check_commands(structured=True, extended=False)
+
+    def test_commands_extended_headers(self):
+        self.check_commands(structured=True, extended=True)
+
     def test_cache_past_end_of_export(self):
         self.assertRaises(nbd.Error, self.h.cache, size + 1, 0)
 
diff --git a/tests/qemu-iotests/tests/nbd-commands.out b/tests/qemu-iotests/tests/nbd-commands.out
index 8d7e9967009..3f8a935a082 100644
--- a/tests/qemu-iotests/tests/nbd-commands.out
+++ b/tests/qemu-iotests/tests/nbd-commands.out
@@ -1,5 +1,5 @@
-...
+......
 ----------------------------------------------------------------------
-Ran 3 tests
+Ran 6 tests
 
 OK
-- 
2.53.0