[Libguestfs] [PATCH libnbd discussion only 0/5] api: Implement concurrent writer.

[Richard W.M. Jones]

This works, but there's no time saving and I'm still investigating
whether it does what I think it does.  Nevertheless I thought I would
post it because it (probably) implements the idea I had last night
outlined in:

https://www.redhat.com/archives/libguestfs/2019-June/msg00010.html

The meat of the change is patch 4.  Patch 5 is an example which I
would probably fold into patch 4 for submission.  The others are
non-controversial documentation and refactorings to prepare for the
change.

Rich.