[PATCH hci-8.1 v5 0/5] vhost-blk: switch from VHOST_SET_NWORKERS to the mainstream worker ioctls

[Alexander Ivanov <alexander.ivanov@virtuozzo.com>]

The kernel drops our VHOST_SET_NWORKERS ioctl in favour of the
mainstream VHOST_NEW_WORKER/VHOST_ATTACH_VRING_WORKER, which vhost-blk
now supports.

Patch 1 wraps VHOST_SET_FORK_FROM_OWNER in a vhost backend op. Patch 2
refuses num-queues above VHOST_BLK_MAX_QUEUES at realize. Patch 3 is a
cleanup taking &s->dev into a local pointer. Patch 4 makes vhost-blk
create its num-threads workers with the mainstream ioctls, keeping the
same worker layout, and fail to start if the kernel cannot provide
them. Patch 5 drops VHOST_SET_NWORKERS from linux-headers.

v5:
- patch 4: fail to start vhost-blk on any worker ioctl failure instead
  of warning and running on fewer threads than requested
- patch 4: switch to vhost_task mode for num-threads=1 as well, so the
  default thread is of the same kind whatever the number of workers

v4:
- new patch 3: split the &s->dev -> hdev conversion out of patch 4
- patch 2: quote the error realize fails with, add Fixes:
- patch 4: do not key on the errno; on any worker ioctl failure warn
  and continue with the threads created so far instead of failing
  to start vhost-blk
- patch 4: drop the comments, explain in the commit message instead

v3:
- new patch 1: call VHOST_SET_FORK_FROM_OWNER, VHOST_NEW_WORKER and
  VHOST_ATTACH_VRING_WORKER through vhost_ops instead of raw ioctls
- new patch 2: refuse num-queues above VHOST_BLK_MAX_QUEUES at realize
  instead of clamping num-threads in patch 3
- patch 3: create each worker right before attaching its first vq

v2:
- patch 1: clamp num-threads to VHOST_BLK_MAX_QUEUES
- patch 1: note in the commit message that our kernel, unlike
  mainline, defaults to kthreads

https://virtuozzo.atlassian.net/browse/VSTOR-107537

Alexander Ivanov (5):
  vhost-backend: add vhost_set_fork_from_owner op
  vhost-blk: reject num-queues above VHOST_BLK_MAX_QUEUES
  vhost-blk: use a local vhost_dev pointer in start and stop
  vhost-blk: create kernel threads with the mainstream worker ioctls
  linux-headers: drop VHOST_SET_NWORKERS

 hw/block/vhost-blk.c              | 95 ++++++++++++++++++++++++-------
 hw/virtio/vhost-backend.c         |  7 +++
 include/hw/virtio/vhost-backend.h |  3 +
 linux-headers/linux/vhost.h       |  9 ---
 4 files changed, 86 insertions(+), 28 deletions(-)

-- 
2.53.0