[PATCH v3 0/5] vhost-user block device backend implementation

[Coiby Xu]

v3:
 * separate generic vhost-user-server code from vhost-user-blk-server
   code
 * re-write vu_message_read and kick hander function as coroutines to
   directly call blk_co_preadv, blk_co_pwritev, etc.
 * add aio_context notifier functions to support multi-threading model
 * other fixes regarding coding style, warning report, etc.

v2:
 * Only enable this feauture for Linux because eventfd is a Linux-specific
   feature


This patch series is an implementation of vhost-user block device
backend server, thanks to Stefan and Kevin's guidance.

Vhost-user block device backend server is a UserCreatable object and can be
started using object_add,

 (qemu) object_add 
vhost-user-blk-server,id=ID,unix-socket=/tmp/vhost-user-blk_vhost.socket,node-name=DRIVE_NAME,writable=off,blk-size=512
 (qemu) object_del ID

or appending the "-object" option when starting QEMU,

  $ -object 
vhost-user-blk-server,id=disk,unix-socket=/tmp/vhost-user-blk_vhost.socket,node-name=DRIVE_NAME,writable=off,blk-size=512

Then vhost-user client can connect to the server backend.
For example, QEMU could act as a client,

  $ -m 256 -object memory-backend-memfd,id=mem,size=256M,share=on -numa 
node,memdev=mem -chardev socket,id=char1,path=/tmp/vhost-user-blk_vhost.socket 
-device vhost-user-blk-pci,id=blk0,chardev=char1

And guest OS could access this vhost-user block device after mouting it.

Coiby Xu (5):
  extend libvhost to support IOThread and coroutine
  generic vhost user server
  vhost-user block device backend server
  a standone-alone tool to directly share disk image file via vhost-user
    protocol
  new qTest case to test the vhost-user-blk-server

 Makefile                              |   4 +
 Makefile.target                       |   1 +
 backends/Makefile.objs                |   2 +
 backends/vhost-user-blk-server.c      | 716 ++++++++++++++++++++++++++
 backends/vhost-user-blk-server.h      |  21 +
 configure                             |   3 +
 contrib/libvhost-user/libvhost-user.c |  54 +-
 contrib/libvhost-user/libvhost-user.h |  38 +-
 qemu-vu.c                             | 252 +++++++++
 tests/libqos/vhost-user-blk.c         | 126 +++++
 tests/libqos/vhost-user-blk.h         |  44 ++
 tests/vhost-user-blk-test.c           | 694 +++++++++++++++++++++++++
 util/Makefile.objs                    |   3 +
 util/vhost-user-server.c              | 429 ++++++++++++++++
 util/vhost-user-server.h              |  56 ++
 vl.c                                  |   4 +
 16 files changed, 2440 insertions(+), 7 deletions(-)
 create mode 100644 backends/vhost-user-blk-server.c
 create mode 100644 backends/vhost-user-blk-server.h
 create mode 100644 qemu-vu.c
 create mode 100644 tests/libqos/vhost-user-blk.c
 create mode 100644 tests/libqos/vhost-user-blk.h
 create mode 100644 tests/vhost-user-blk-test.c
 create mode 100644 util/vhost-user-server.c
 create mode 100644 util/vhost-user-server.h

--
2.25.0