This series addresses the problem described in these bug reports:
https://gitlab.com/qemu-project/qemu/-/issues/1330
https://bugzilla.redhat.com/show_bug.cgi?id=2147617
qcow2 can fail when writing back dirty bitmaps in qcow2_inactivate().
However, when the function is called through blk_unref(), in the case of
such errors, while an error message is written to stderr, the callers
never see an error return. Specifically, 'qemu-img bitmap/commit' are
reported to exit with an exit code 0 despite the errors.
The solution taken here is inactivating the images first, which can
still return errors, but already performs all of the write operations.
Only then the images are actually blk_unref()-ed.