Merge v6.16-rc2 into timers/ptp

Krzysztof Wilczyński <kwilczynski@kernel.org> <kw@linux.com>

Kshitiz Godara <quic_kgodara@quicinc.com> <kgodara@codeaurora.org>

Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

Kuniyuki Iwashima <kuniyu@google.com> <kuniyu@amazon.com>

Kuniyuki Iwashima <kuniyu@google.com> <kuniyu@amazon.co.jp>

Kuniyuki Iwashima <kuniyu@google.com> <kuni1840@gmail.com>

Kuogee Hsieh <quic_khsieh@quicinc.com> <khsieh@codeaurora.org>

Lee Jones <lee@kernel.org> <joneslee@google.com>

Lee Jones <lee@kernel.org> <lee.jones@canonical.com>

Sriram R <quic_srirrama@quicinc.com> <srirrama@codeaurora.org>

Sriram Yagnaraman <sriram.yagnaraman@ericsson.com> <sriram.yagnaraman@est.tech>

Stanislav Fomichev <sdf@fomichev.me> <sdf@google.com>

Stanislav Fomichev <sdf@fomichev.me> <stfomichev@gmail.com>

Stefan Wahren <wahrenst@gmx.net> <stefan.wahren@i2se.com>

Stéphane Witzmann <stephane.witzmann@ubpmes.univ-bpclermont.fr>

Stephen Hemminger <stephen@networkplumber.org> <shemminger@linux-foundation.org>

illegal Windows/NTFS/SMB characters to a remap range (this mount parameter

is the default for SMB3). This remap (``mapposix``) range is also

compatible with Mac (and "Services for Mac" on some older Windows).

When POSIX Extensions for SMB 3.1.1 are negotiated, remapping is automatically

disabled.

CIFS VFS Mount Options

======================

parameter of `struct ublk_param_segment` with backend for avoiding

unnecessary IO split, which usually hurts io_uring performance.

Auto Buffer Registration

------------------------

The ``UBLK_F_AUTO_BUF_REG`` feature automatically handles buffer registration

and unregistration for I/O requests, which simplifies the buffer management

process and reduces overhead in the ublk server implementation.

This is another feature flag for using zero copy, and it is compatible with

``UBLK_F_SUPPORT_ZERO_COPY``.

Feature Overview

~~~~~~~~~~~~~~~~

This feature automatically registers request buffers to the io_uring context

before delivering I/O commands to the ublk server and unregisters them when

completing I/O commands. This eliminates the need for manual buffer

registration/unregistration via ``UBLK_IO_REGISTER_IO_BUF`` and

``UBLK_IO_UNREGISTER_IO_BUF`` commands, then IO handling in ublk server

can avoid dependency on the two uring_cmd operations.

IOs can't be issued concurrently to io_uring if there is any dependency

among these IOs. So this way not only simplifies ublk server implementation,

but also makes concurrent IO handling becomes possible by removing the

dependency on buffer registration & unregistration commands.

Usage Requirements

~~~~~~~~~~~~~~~~~~

1. The ublk server must create a sparse buffer table on the same ``io_ring_ctx``

   used for ``UBLK_IO_FETCH_REQ`` and ``UBLK_IO_COMMIT_AND_FETCH_REQ``. If

   uring_cmd is issued on a different ``io_ring_ctx``, manual buffer

   unregistration is required.

2. Buffer registration data must be passed via uring_cmd's ``sqe->addr`` with the

   following structure::

    struct ublk_auto_buf_reg {

        __u16 index;      /* Buffer index for registration */

        __u8 flags;       /* Registration flags */

        __u8 reserved0;   /* Reserved for future use */

        __u32 reserved1;  /* Reserved for future use */

    };

   ublk_auto_buf_reg_to_sqe_addr() is for converting the above structure into

   ``sqe->addr``.

3. All reserved fields in ``ublk_auto_buf_reg`` must be zeroed.

4. Optional flags can be passed via ``ublk_auto_buf_reg.flags``.

Fallback Behavior

~~~~~~~~~~~~~~~~~

If auto buffer registration fails:

1. When ``UBLK_AUTO_BUF_REG_FALLBACK`` is enabled:

   - The uring_cmd is completed

   - ``UBLK_IO_F_NEED_REG_BUF`` is set in ``ublksrv_io_desc.op_flags``

   - The ublk server must manually deal with the failure, such as, register

     the buffer manually, or using user copy feature for retrieving the data

     for handling ublk IO

2. If fallback is not enabled:

   - The ublk I/O request fails silently

   - The uring_cmd won't be completed

Limitations

~~~~~~~~~~~

- Requires same ``io_ring_ctx`` for all operations

- May require manual buffer management in fallback cases

- io_ring_ctx buffer table has a max size of 16K, which may not be enough

  in case that too many ublk devices are handled by this single io_ring_ctx

  and each one has very large queue depth

References

==========

  Some peripherals such as PWM have their I/O go through the 4 "GPIOs".

maintainers:

  - Jianlong Huang <jianlong.huang@starfivetech.com>

  - Hal Feng <hal.feng@starfivetech.com>

properties:

  compatible:

  any GPIO can be set up to be controlled by any of the peripherals.

maintainers:

  - Jianlong Huang <jianlong.huang@starfivetech.com>

  - Hal Feng <hal.feng@starfivetech.com>

properties:

  compatible: