[PATCH for-next v2 0/4] fixed-buffer for uring-cmd/passthrough

[Kanchan Joshi <joshi.k@samsung.com>]

Hi,

Currently uring-cmd lacks the ability to leverage the pre-registered
buffers. This series adds new fixed-buffer variant of uring command
IORING_OP_URING_CMD_FIXED, and plumbs nvme passthrough to work with
that.

Patch 1, 3 = prep/infrastructure
Patch 2 = expand io_uring command to use registered-buffers
Patch 4 = expand nvme passthrough to use registered-buffers

Using registered-buffers showed 9-12% IOPS gain in my setup.
QD   Without     With
8     853        928
32    1370       1528
128   1505       1631

This series is prepared on top of:
for-next + iopoll-passthru series [1] + passthru optimization series [2].
A unified branch with all that is present here:
https://github.com/OpenMPDK/linux/commits/feat/pt_fixedbufs_v1

Fio that can use IORING_OP_URING_CMD_FIXED (on specifying fixedbufs=1)
is here -
https://github.com/joshkan/fio/commit/300f1187f75aaf2c502c180041943c340670d0ac

Changes since v1:
- Fix a naming issue for an exported helper

[1] https://lore.kernel.org/linux-block/20220807183607.352351-1-joshi.k@samsung.com/
[2] https://lore.kernel.org/linux-block/20220806152004.382170-1-axboe@kernel.dk/

Anuj Gupta (2):
  io_uring: introduce io_uring_cmd_import_fixed
  io_uring: introduce fixed buffer support for io_uring_cmd

Kanchan Joshi (2):
  block: add helper to map bvec iterator for passthrough
  nvme: wire up fixed buffer support for nvme passthrough

 block/blk-map.c               | 71 +++++++++++++++++++++++++++++++++++
 drivers/nvme/host/ioctl.c     | 38 +++++++++++++------
 include/linux/blk-mq.h        |  1 +
 include/linux/io_uring.h      | 10 +++++
 include/uapi/linux/io_uring.h |  1 +
 io_uring/opdef.c              | 10 +++++
 io_uring/rw.c                 |  3 +-
 io_uring/uring_cmd.c          | 26 +++++++++++++
 8 files changed, 147 insertions(+), 13 deletions(-)

-- 
2.25.1