tests: fix broken deduplication check in parallels format test

Original check is broken as supposed reading from 2 different clusters
results in read from the same file offset twice. This is definitely
wrong.

We should be sure that
* the content of both clusters is correct after repair
* clusters are at the different offsets after repair
In order to check the latter we write some content into the first one
and validate that fact.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>

tests/qemu-iotests/tests/parallels-checks

@@ -117,14 +117,20 @@ echo "== check second cluster =="
 echo "== repair image =="
 _check_test_img -r all
 
+echo "== check the first cluster =="
+{ $QEMU_IO -r -c "read -P 0x11 0 $CLUSTER_SIZE" "$TEST_IMG"; } 2>&1 | _filter_qemu_io | _filter_testdir
+
 echo "== check second cluster =="
 { $QEMU_IO -r -c "read -P 0x11 $CLUSTER_SIZE $CLUSTER_SIZE" "$TEST_IMG"; } 2>&1 | _filter_qemu_io | _filter_testdir
 
-echo "== check first cluster on host =="
-printf "content: 0x%02x\n" `peek_file_le $TEST_IMG $(($CLUSTER_SIZE)) 1`
+echo "== write another pattern to the first clusters =="
+{ $QEMU_IO -c "write -P 0x66 0 $CLUSTER_SIZE" "$TEST_IMG"; } 2>&1 | _filter_qemu_io | _filter_testdir
+
+echo "== check the first cluster =="
+{ $QEMU_IO -r -c "read -P 0x66 0 $CLUSTER_SIZE" "$TEST_IMG"; } 2>&1 | _filter_qemu_io | _filter_testdir
 
-echo "== check second cluster on host =="
-printf "content: 0x%02x\n" `peek_file_le $TEST_IMG $(($CLUSTER_SIZE)) 1`
+echo "== check the second cluster (deduplicated) =="
+{ $QEMU_IO -r -c "read -P 0x11 $CLUSTER_SIZE $CLUSTER_SIZE" "$TEST_IMG"; } 2>&1 | _filter_qemu_io | _filter_testdir
 
 # Clear image
 _make_test_img $SIZE

tests/qemu-iotests/tests/parallels-checks.out

@@ -55,13 +55,21 @@ The following inconsistencies were found and repaired:
 
 Double checking the fixed image now...
 No errors were found on the image.
+== check the first cluster ==
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 == check second cluster ==
 read 1048576/1048576 bytes at offset 1048576
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-== check first cluster on host ==
-content: 0x11
-== check second cluster on host ==
-content: 0x11
+== write another pattern to the first clusters ==
+wrote 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+== check the first cluster ==
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+== check the second cluster (deduplicated) ==
+read 1048576/1048576 bytes at offset 1048576
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4194304
 == TEST DATA_OFF CHECK ==
 == write pattern to first cluster ==