block: Convert bs->backing_hd to BdrvChild

This is the final step in converting all of the BlockDriverState
pointers that block drivers use to BdrvChild.

After this patch, bs->children contains the full list of child nodes
that are referenced by a given BDS, and these children are only
referenced through BdrvChild, so that updating the pointer in there is
enough for changing edges in the graph.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/qemu-img.c b/qemu-img.c
index 7d65c0a..e678fdc 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -748,7 +748,7 @@ static int img_commit(int argc, char **argv)
         /* This is different from QMP, which by default uses the deepest file in
          * the backing chain (i.e., the very base); however, the traditional
          * behavior of qemu-img commit is using the immediate backing file. */
-        base_bs = bs->backing_hd;
+        base_bs = backing_bs(bs);
         if (!base_bs) {
             error_setg(&local_err, "Image does not have a backing file");
             goto done;
@@ -2207,7 +2207,7 @@ static int get_block_status(BlockDriverState *bs, int64_t sector_num,
         if (ret & (BDRV_BLOCK_ZERO|BDRV_BLOCK_DATA)) {
             break;
         }
-        bs = bs->backing_hd;
+        bs = backing_bs(bs);
         if (bs == NULL) {
             ret = 0;
             break;