[PATCH v2 0/5] dma-buf backed NVMe passthrough I/O

[Anuj Gupta <anuj1072538@gmail.com>]

This series adds support for dma-buf registered buffers in NVMe
uring_cmd passthrough.

It depends on this fix:
https://lore.kernel.org/io-uring/20261022132027.2293931-1-anuj1072538@gmail.com/

Patches 1-2 add import flags to the fixed buffer import helpers, so
uring_cmd users have to opt in to dma-buf. Patch 3 adds the io_uring
side, patch 4 lets the block layer map dma-buf iterators for
passthrough, and patch 5 enables it for the NVMe namespace character
device.

Tested with this liburing test:
https://github.com/anuj7781/liburing/tree/rw-dmabuf-pt

Changes since v1:
- split into io_uring, block and nvme patches (Christoph)
- pass import flags to io_import_reg_buf() and
  io_uring_cmd_import_fixed(), and make callers opt in to dma-buf
  (Christoph, Pavel)
- add io_uring_cmd_hw_done(), so nvme no longer handles the dma-buf
  map (Pavel)
- warn if task_work is queued with a dma-buf map attached (Pavel)
- make the -EREMOTEIO conversion explicit and comment it (Christoph)
- refuse dma-bufs larger than 4GiB on the character device

v1: https://lore.kernel.org/linux-nvme/20261016103453.1129150-1-anuj1072538@gmail.com/

Anuj Gupta (5):
  io_uring/rsrc: pass import flags to io_import_reg_buf()
  io_uring/uring_cmd: add import flags to io_uring_cmd_import_fixed()
  io_uring/uring_cmd: support dma-buf registered buffers
  block: map dma-buf iterators in blk_rq_map_user_iov()
  nvme: support dma-buf registered buffers for passthrough

 block/blk-map.c              | 15 ++++++++++++++-
 drivers/nvme/host/core.c     | 16 ++++++++++++++++
 drivers/nvme/host/ioctl.c    |  5 +++--
 drivers/scsi/scsi_bsg.c      |  2 +-
 fs/fuse/dev_uring.c          |  2 +-
 include/linux/io_uring/cmd.h | 14 ++++++++++++--
 io_uring/net.c               |  6 +++---
 io_uring/rsrc.c              |  6 +++---
 io_uring/rsrc.h              | 13 +++----------
 io_uring/rw.c                |  5 +++--
 io_uring/uring_cmd.c         | 31 +++++++++++++++++++++++++++++--
 11 files changed, 88 insertions(+), 27 deletions(-)


base-commit: fd13f31ac62abac4df2166bb0a6fbff53b288e0c
prerequisite-patch-id: 6ad52e1ffc603df71c6855926838f2df402c3ed1
-- 
2.43.0