block: Connect BlockBackend to BlockDriverState

Convenience function blk_new_with_bs() creates a BlockBackend with its
BlockDriverState.  Callers have to unref both.  The commit after next
will relieve them of the need to unref the BlockDriverState.

Complication: due to the silly way drive_del works, we need a way to
hide a BlockBackend, just like bdrv_make_anon().  To emphasize its
"special" status, give the function a suitably off-putting name:
blk_hide_on_behalf_of_do_drive_del().  Unfortunately, hiding turns the
BlockBackend's name into the empty string.  Can't avoid that without
breaking the blk->bs->device_name equals blk->name invariant.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 634ba11..f741973 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -692,8 +692,8 @@ int main(int argc, char **argv)
         drv = NULL;
     }
 
-    blk = blk_new("hda", &error_abort);
-    bs = bdrv_new_root("hda", &error_abort);
+    blk = blk_new_with_bs("hda", &error_abort);
+    bs = blk_bs(blk);
 
     srcpath = argv[optind];
     ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err);