[Libguestfs] [PATCH libnbd v2 0/4] api: Implement concurrent writer.

[Richard W.M. Jones]

v1:
https://www.redhat.com/archives/libguestfs/2019-June/msg00014.html

I pushed a few bits which are uncontroversial.  The main
changes since v1 are:

An extra patch removes the want_to_send / check for nbd_aio_is_ready
in examples/threaded-reads-and-writes.c.  This logic was wrong since
commit 6af72b87 as was pointed out by Eric in his review.  Comments
and structure of examples/concurrent-writes.c has been updated to
match.

Callbacks now return int instead of void.  In some cases we ignore
this return value.

I added a lot more commentary in the commit message for the main patch
(now patch 3 in this series).

Rich.