Ok, as I expected simple changes in a previous based-on serie provoke a
cascade of changes that inevitably affect these patches too.
While I strongly suggest to have an initial look at these patches
because it gives an idea on what am I trying to accomplish, I would not
go looking at nitpicks and
Please read "Protect the block layer with a rwlock: part 1" for an additional
introduction and aim of this series.
This second part aims to add the graph rdlock to the BlockDriver functions
that already run in coroutine context and are classified as IO.
Such functions will recursively traverse
