block: Add bdrv_change_backing_file

Introduce the functions needed to change the backing file of an image. The
function is implemented for qcow2.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/block_int.h b/block_int.h
index 9a3b2e09de..a0ebd90a0b 100644
--- a/block_int.h
+++ b/block_int.h
@@ -98,6 +98,9 @@ struct BlockDriver {
     int (*bdrv_load_vmstate)(BlockDriverState *bs, uint8_t *buf,
                              int64_t pos, int size);
 
+    int (*bdrv_change_backing_file)(BlockDriverState *bs,
+        const char *backing_file, const char *backing_fmt);
+
     /* removable device specific */
     int (*bdrv_is_inserted)(BlockDriverState *bs);
     int (*bdrv_media_changed)(BlockDriverState *bs);