[Qemu-devel] [PATCH] iotests: Tweak 030 in order to trigger a race condition with parallel jobs

[Alberto Garcia <berto@igalia.com>]

This patch tweaks TestParallelOps in iotest 030 so it allocates data
in smaller regions (256KB/512KB instead of 512KB/1MB) and the
block-stream job in test_stream_commit() only needs to copy data that
is at the very end of the image.

This way when the block-stream job is waken up it will finish right
away without any chance of being stopped by block_job_sleep_ns(). This
triggers the bug that was fixed by 3d5d319e1221082974711af1d09d82f07
and is therefore a more useful test case for parallel block jobs.

After this patch the aforementiond bug can also be reproduced with the
test_stream_parallel() test case.

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 tests/qemu-iotests/030 | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/030 b/tests/qemu-iotests/030
index 457984b8e9..230eb761dd 100755
--- a/tests/qemu-iotests/030
+++ b/tests/qemu-iotests/030
@@ -156,7 +156,7 @@ class TestSingleDrive(iotests.QMPTestCase):
 class TestParallelOps(iotests.QMPTestCase):
     num_ops = 4 # Number of parallel block-stream operations
     num_imgs = num_ops * 2 + 1
-    image_len = num_ops * 1024 * 1024
+    image_len = num_ops * 512 * 1024
     imgs = []
 
     def setUp(self):
@@ -177,12 +177,12 @@ class TestParallelOps(iotests.QMPTestCase):
 
         # Put data into the images we are copying data from
         for i in range(self.num_imgs / 2):
-            img_index = i * 2 + 1
-            # Alternate between 512k and 1M.
+            img_index = self.num_imgs - i * 2 - 2
+            # Alternate between 256KB and 512KB.
             # This way jobs will not finish in the same order they were created
-            num_kb = 512 + 512 * (i % 2)
+            num_kb = 256 + 256 * (i % 2)
             qemu_io('-f', iotests.imgfmt,
-                    '-c', 'write -P %d %d %d' % (i, i*1024*1024, num_kb * 1024),
+                    '-c', 'write -P 0xFF %dk %dk' % (i * 512, num_kb),
                     self.imgs[img_index])
 
         # Attach the drive to the VM
@@ -323,7 +323,7 @@ class TestParallelOps(iotests.QMPTestCase):
         self.assert_no_active_block_jobs()
 
         # Stream from node0 into node2
-        result = self.vm.qmp('block-stream', device='node2', job_id='node2')
+        result = self.vm.qmp('block-stream', device='node2', base_node='node0', job_id='node2')
         self.assert_qmp(result, 'return', {})
 
         # Commit from the active layer into node3
-- 
2.11.0