[PATCH 64/97] iotests: Test backup job with two guest writes

[Michael Roth]

From: Max Reitz <address@hidden>

Perform two guest writes to not yet backed up areas of an image, where
the former touches an inner area of the latter.

Before HEAD^, copy offloading broke this in two ways:
(1) The target image differs from the reference image (what the source
    was when the backup started).
(2) But you will not see that in the failing output, because the job
    offset is reported as being greater than the job length.  This is
    because one cluster is copied twice, and thus accounted for twice,
    but of course the job length does not increase.

Signed-off-by: Max Reitz <address@hidden>
Message-id: address@hidden
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Tested-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
(cherry picked from commit 5f594a2e99f19ca0f7744d333bcd556f5976b78f)
Signed-off-by: Michael Roth <address@hidden>
---
 tests/qemu-iotests/056     | 39 ++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/056.out |  4 ++--
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/056 b/tests/qemu-iotests/056
index 3df323984d..e5ac25127b 100755
--- a/tests/qemu-iotests/056
+++ b/tests/qemu-iotests/056
@@ -133,6 +133,7 @@ class BackupTest(iotests.QMPTestCase):
         self.vm = iotests.VM()
         self.test_img = img_create('test')
         self.dest_img = img_create('dest')
+        self.ref_img = img_create('ref')
         self.vm.add_drive(self.test_img)
         self.vm.launch()
 
@@ -140,6 +141,7 @@ class BackupTest(iotests.QMPTestCase):
         self.vm.shutdown()
         try_remove(self.test_img)
         try_remove(self.dest_img)
+        try_remove(self.ref_img)
 
     def hmp_io_writes(self, drive, patterns):
         for pattern in patterns:
@@ -177,6 +179,43 @@ class BackupTest(iotests.QMPTestCase):
             self.assert_qmp(event, 'data/error', qerror)
             return False
 
+    def test_overlapping_writes(self):
+        # Write something to back up
+        self.hmp_io_writes('drive0', [('42', '0M', '2M')])
+
+        # Create a reference backup
+        self.qmp_backup_and_wait(device='drive0', format=iotests.imgfmt,
+                                 sync='full', target=self.ref_img,
+                                 auto_dismiss=False)
+        res = self.vm.qmp('block-job-dismiss', id='drive0')
+        self.assert_qmp(res, 'return', {})
+
+        # Now to the test backup: We simulate the following guest
+        # writes:
+        # (1) [1M + 64k, 1M + 128k): Afterwards, everything in that
+        #     area should be in the target image, and we must not copy
+        #     it again (because the source image has changed now)
+        #     (64k is the job's cluster size)
+        # (2) [1M, 2M): The backup job must not get overeager.  It
+        #     must copy [1M, 1M + 64k) and [1M + 128k, 2M) separately,
+        #     but not the area in between.
+
+        self.qmp_backup(device='drive0', format=iotests.imgfmt, sync='full',
+                        target=self.dest_img, speed=1, auto_dismiss=False)
+
+        self.hmp_io_writes('drive0', [('23', '%ik' % (1024 + 64), '64k'),
+                                      ('66', '1M', '1M')])
+
+        # Let the job complete
+        res = self.vm.qmp('block-job-set-speed', device='drive0', speed=0)
+        self.assert_qmp(res, 'return', {})
+        self.qmp_backup_wait('drive0')
+        res = self.vm.qmp('block-job-dismiss', id='drive0')
+        self.assert_qmp(res, 'return', {})
+
+        self.assertTrue(iotests.compare_images(self.ref_img, self.dest_img),
+                        'target image does not match reference image')
+
     def test_dismiss_false(self):
         res = self.vm.qmp('query-block-jobs')
         self.assert_qmp(res, 'return', [])
diff --git a/tests/qemu-iotests/056.out b/tests/qemu-iotests/056.out
index dae404e278..36376bed87 100644
--- a/tests/qemu-iotests/056.out
+++ b/tests/qemu-iotests/056.out
@@ -1,5 +1,5 @@
-.........
+..........
 ----------------------------------------------------------------------
-Ran 9 tests
+Ran 10 tests
 
 OK
-- 
2.17.1