[PATCH 0/7] add support for uring passthrough commands

[Ankit Kumar <ankit.kumar@samsung.com>]

This patchset adds a new I/O engine (io_uring_cmd), which enables support for
io_uring passthrough commands. The new I/O engine will be built only if its
support is present in the kernel.
https://git.kernel.dk/cgit/linux-block/log/?h=for-next

This engine will use most of the existing helpers from io_uring. The I/O
preparation, completion, file open, file close and post init paths are going
to differ and hence io_uring_cmd will have its own helper for them.

The supported io_uring_cmd options are:
* registerfiles
* sqthread_poll
* sqthread_poll_cpu
* cmd_type (new)

The current uring passthrough support is present only with nvme-ns character
device (/dev/ngXnY). This includes both conventional as well as ZNS devices.
cmd_type provides the flexibility to support different types of passthrough
commands in future.
O_DIRECT flag support is not present with nvme-ns charatcer devices, hence
zbd will check for them only if fio filetype is a block device.

To enable support for nvme passthrough commands, fio will use libnvme to use
NVMe specification structures, enums and helper functions for sending commands.
As nvme specific uring_cmd changes are not yet part of mainline kernel, they
are not integrated with libnvme. Below is the PR for libnvme changes.
https://github.com/linux-nvme/libnvme/pull/362

NOTE: The io_uring_cmd I/O engine changes are present in engines/io_uring.c
These changes are guarded with config flags CONFIG_URING_CMD and
CONFIG_LIBNVME which makes the code a bit messy. This can be neat if
io_uring_cmd is decoupled from engines/io_uring.c

Ankit Kumar (4):
  configure: check if uring_cmd support is present
  docs: document options for io_uring_cmd I/O engine
  zbd: Check for direct flag only if its block device
  engines/io_uring: Enable zone device support for io_uring_cmd I/O
    engine

Anuj Gupta (3):
  io_uring.h: add IORING_SETUP_SQE128 and IORING_SETUP_CQE32
  engines/io_uring: add new I/O engine for uring passthrough support
  examples: add 2 example job file for io_uring_cmd engine

 HOWTO.rst                    |  17 +-
 Makefile                     |   4 +
 configure                    |  45 +++
 engines/io_uring.c           | 686 ++++++++++++++++++++++++++++++++++-
 examples/uring-cmd-ng.fio    |  35 ++
 examples/uring-cmd-zoned.fio |  40 ++
 file.h                       |  12 +-
 fio.1                        |  19 +-
 os/linux/io_uring.h          |  45 ++-
 zbd.c                        |   4 +-
 10 files changed, 886 insertions(+), 21 deletions(-)
 create mode 100644 examples/uring-cmd-ng.fio
 create mode 100644 examples/uring-cmd-zoned.fio

-- 
2.17.1