qcow2: Fix src_offset in copy offloading

Not updating src_offset will result in wrong data being written to dst
image.

Reported-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/qcow2.c

@@ -3387,6 +3387,7 @@ qcow2_co_copy_range_to(BlockDriverState *bs,
         }
 
         bytes -= cur_bytes;
+        src_offset += cur_bytes;
         dst_offset += cur_bytes;
     }
     ret = 0;

tests/qemu-iotests/063

@@ -91,6 +91,15 @@ if $QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n "$TEST_IMG.orig" "$TEST_IMG" >/dev
     exit 1
 fi
 
+echo "== Regression testing for copy offloading bug =="
+
+_make_test_img 1M
+TEST_IMG="$TEST_IMG.target" _make_test_img 1M
+$QEMU_IO -c 'write -P 1 0 512k' -c 'write -P 2 512k 512k' "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c 'write -P 4 512k 512k' -c 'write -P 3 0 512k' "$TEST_IMG.target" | _filter_qemu_io
+$QEMU_IMG convert -n -O $IMGFMT "$TEST_IMG" "$TEST_IMG.target"
+$QEMU_IMG compare "$TEST_IMG" "$TEST_IMG.target"
+
 echo "*** done"
 rm -f $seq.full
 status=0

tests/qemu-iotests/063.out

@@ -7,4 +7,16 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4194304
 No errors were found on the image.
 == Testing conversion to a smaller file fails ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2097152
+== Regression testing for copy offloading bug ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
+Formatting 'TEST_DIR/t.IMGFMT.target', fmt=IMGFMT size=1048576
+wrote 524288/524288 bytes at offset 0
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 524288/524288 bytes at offset 524288
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 524288/524288 bytes at offset 524288
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 524288/524288 bytes at offset 0
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Images are identical.
 *** done