If a new bitmap entry is allocated, requiring the entire block to be
written, avoiding leaking the buffer allocated for the block should
the write fail.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Edmondson <david.edmondson@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Max Reitz <mreitz@redhat.com>
Message-id: 20210325112941.365238-2-pbonzini@redhat.com
Message-Id: <20210309144015.557477-2-david.edmondson@oracle.com>
Acked-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>