Put an NBD block device into an I/O thread, and then read data from it,
hoping that the NBD connection will yield during that read. When it
does, the coroutine must be reentered in the block device's I/O thread,
which will only happen if the NBD block driver attaches the connection's
QIOChannel to the new AioContext. It did not do that after 4ddb5d2fde
("block/nbd: drop connection_co") and prior to "block/nbd: Move s->ioc
on AioContext change", which would cause an assertion failure.
To improve our chances of yielding, the NBD server is throttled to
reading 64 kB/s, and the NBD client reads 128 kB, so it should yield at
some point.
Signed-off-by: Hanna Reitz
---
tests/qemu-iotests/281 | 28 +---
tests/qemu-iotests/281.out | 4 ++--
2 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/tests/qemu-iotests/281 b/tests/qemu-iotests/281
index 4fb3cd30dd..5e1339bd75 100755
--- a/tests/qemu-iotests/281
+++ b/tests/qemu-iotests/281
@@ -253,8 +253,9 @@ class TestYieldingAndTimers(iotests.QMPTestCase):
self.create_nbd_export()
# Simple VM with an NBD block device connected to the NBD export
-# provided by the QSD
+# provided by the QSD, and an (initially unused) iothread
self.vm = iotests.VM()
+self.vm.add_object('iothread,id=iothr')
self.vm.add_blockdev('nbd,node-name=nbd,server.type=unix,' +
f'server.path={self.sock},export=exp,' +
'reconnect-delay=1,open-timeout=1')
@@ -299,19 +300,40 @@ class TestYieldingAndTimers(iotests.QMPTestCase):
# thus not see the error, and so the test will pass.)
time.sleep(2)
+def test_yield_in_iothread(self):
+# Move the NBD node to the I/O thread; the NBD block driver should
+# attach the connection's QIOChannel to that thread's AioContext, too
+result = self.vm.qmp('x-blockdev-set-iothread',
+ node_name='nbd', iothread='iothr')
+self.assert_qmp(result, 'return', {})
+
+# Do some I/O that will be throttled by the QSD, so that the network
+# connection hopefully will yield here. When it is resumed, it must
+# then be resumed in the I/O thread's AioContext.
+result = self.vm.qmp('human-monitor-command',
+ command_line='qemu-io nbd "read 0 128K"')
+self.assert_qmp(result, 'return', '')
+
def create_nbd_export(self):
assert self.qsd is None
-# Simple NBD export of a null-co BDS
+# Export a throttled null-co BDS: Reads are throttled (max 64 kB/s),
+# writes are not.
self.qsd = QemuStorageDaemon(
+'--object',
+'throttle-group,id=thrgr,x-bps-read=65536,x-bps-read-max=65536',
+
'--blockdev',
'null-co,node-name=null,read-zeroes=true',
+'--blockdev',
+'throttle,node-name=thr,file=null,throttle-group=thrgr',
+
'--nbd-server',
f'addr.type=unix,addr.path={self.sock}',
'--export',
-'nbd,id=exp,node-name=null,name=exp,writable=true'
+'nbd,id=exp,node-name=thr,name=exp,writable=true'
)
def stop_nbd_export(self):
diff --git a/tests/qemu-iotests/281.out b/tests/qemu-iotests/281.out
index 914e3737bd..3f8a935a08 100644
--- a/tests/qemu-iotests/281.out
+++ b/tests/qemu-iotests/281.out
@@ -1,5 +1,5 @@
-.
+..
--
-Ran 5 tests
+Ran 6 tests
OK
--
2.34.1
