[PATCH v10 0/7] vhost-user block device backend implementation

[Coiby Xu <coiby.xu@gmail.com>]

v10
 - Use a linked list of VuFdWatch objects to keep kick info [Stefan]
 - Merge improvements and fixes from Stefan
 - Rename libvhost-user's vu_message_read to vu_message_read_default [Kevin]
 - When shutting down the client, wait for the coroutine of processing
   vhost-user messages to be finished [Kevin]
 - Allocate struct req_data on the heap [Kevin]
 - Improve coding of qtest case [Thomas]
 - Fix several memory leaks detected by ASAN

v9
 - move logical block size check function to a utility function
 - fix issues regarding license, coding style, memory deallocation, etc.

v8
 - re-try connecting to socket server to fix asan error
 - fix license naming issue

v7
 - fix docker-test-debug@fedora errors by freeing malloced memory

v6
 - add missing license header and include guard
 - vhost-user server only serve one client one time
 - fix a bug in custom vu_message_read
 - using qemu-storage-daemon to start vhost-user-blk-server
 - a bug fix to pass docker-test-clang@ubuntu

v5:
 * re-use vu_kick_cb in libvhost-user
 * keeping processing VhostUserMsg in the same coroutine until there is
   detachment/attachment of AIOContext
 * Spawn separate coroutine for each VuVirtqElement
 * Other changes including relocating vhost-user-blk-server.c, coding
   style etc.

v4:
 * add object properties in class_init
 * relocate vhost-user-blk-test
 * other changes including using SocketAddress, coding style, etc.

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 feature 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,logical-block-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,logical-block-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 mounting it.

Coiby Xu (7):
  libvhost-user: Allow vu_message_read to be replaced
  libvhost-user: remove watch for kick_fd when de-initialize vu-dev
  util/vhost-user-server: generic vhost user server
  block: move logical block size check function to a common utility
    function
  block/export: vhost-user block device backend server
  test: new qTest case to test the vhost-user-blk-server
  MAINTAINERS: Add vhost-user block device backend server maintainer

 MAINTAINERS                                |   8 +
 block/export/vhost-user-blk-server.c       | 661 ++++++++++++++++++
 block/export/vhost-user-blk-server.h       |  36 +
 block/meson.build                          |   1 +
 contrib/libvhost-user/libvhost-user-glib.c |   2 +-
 contrib/libvhost-user/libvhost-user.c      |  15 +-
 contrib/libvhost-user/libvhost-user.h      |  21 +
 hw/core/qdev-properties.c                  |  31 +-
 softmmu/vl.c                               |   4 +
 tests/qtest/libqos/libqtest.h              |  17 +
 tests/qtest/libqos/meson.build             |   1 +
 tests/qtest/libqos/vhost-user-blk.c        | 129 ++++
 tests/qtest/libqos/vhost-user-blk.h        |  48 ++
 tests/qtest/libqtest.c                     |  36 +-
 tests/qtest/meson.build                    |   4 +-
 tests/qtest/vhost-user-blk-test.c          | 751 +++++++++++++++++++++
 tests/vhost-user-bridge.c                  |   2 +
 tools/virtiofsd/fuse_virtio.c              |   4 +-
 util/block-helpers.c                       |  46 ++
 util/block-helpers.h                       |  19 +
 util/meson.build                           |   2 +
 util/vhost-user-server.c                   | 428 ++++++++++++
 util/vhost-user-server.h                   |  65 ++
 23 files changed, 2292 insertions(+), 39 deletions(-)
 create mode 100644 block/export/vhost-user-blk-server.c
 create mode 100644 block/export/vhost-user-blk-server.h
 create mode 100644 tests/qtest/libqos/vhost-user-blk.c
 create mode 100644 tests/qtest/libqos/vhost-user-blk.h
 create mode 100644 tests/qtest/vhost-user-blk-test.c
 create mode 100644 util/block-helpers.c
 create mode 100644 util/block-helpers.h
 create mode 100644 util/vhost-user-server.c
 create mode 100644 util/vhost-user-server.h

--
2.28.0