[PATCH 0/8] virtio-blk: remove AioContext lock

[Stefan Hajnoczi]

This is a continuation of Emanuele Esposito's work to remove the AioContext
lock in virtio-blk. In the past it was necessary to acquire the AioContext lock
in order to do I/O. Paolo Bonzini and Emanuele have removed the need for the
AioContext in the core block layer code, with a few exceptions like blk_drain()
and blk_set_aio_context().

This patch series annotates virtio-blk functions with
IO_CODE()/GLOBAL_STATE_CODE() so it's clear in which context they are called.
It also removes unnecessary AioContext locks.

The end result is that virtio-blk rarely takes the AioContext lock. Future
patch series will add support for multiple IOThreads so that true multi-queue
can be achieved, but right now virtio-blk still has unprotected shared state
like s->rq so that needs to wait for another day.

Based-on: <20221102182337.252202-1-stefanha@redhat.com>

Emanuele Giuseppe Esposito (6):
  virtio_queue_aio_attach_host_notifier: remove AioContext lock
  block-backend: enable_write_cache should be atomic
  virtio: categorize callbacks in GS
  virtio-blk: mark GLOBAL_STATE_CODE functions
  virtio-blk: mark IO_CODE functions
  virtio-blk: remove unnecessary AioContext lock from function already
    safe

Stefan Hajnoczi (2):
  virtio-blk: don't acquire AioContext in virtio_blk_handle_vq()
  virtio-blk: minimize virtio_blk_reset() AioContext lock region

 include/block/aio-wait.h        |  4 +-
 block/block-backend.c           |  6 +--
 hw/block/dataplane/virtio-blk.c | 18 +++++--
 hw/block/virtio-blk.c           | 92 ++++++++++++++++++++++++---------
 hw/scsi/virtio-scsi-dataplane.c | 10 ++--
 hw/virtio/virtio-bus.c          |  5 ++
 hw/virtio/virtio-pci.c          |  2 +
 hw/virtio/virtio.c              |  8 +++
 util/aio-wait.c                 |  2 +-
 9 files changed, 106 insertions(+), 41 deletions(-)

-- 
2.38.1