Re: [PATCH 2/6] io_uring: add support for IORING_OP_NAME_TO_HANDLE_AT

[Amir Goldstein <amir73il@gmail.com>]

On Fri, Aug 15, 2025 at 1:51 AM Thomas Bertschinger
<tahbertschinger@gmail.com> wrote:
>
> Add support for name_to_handle_at(2) to io_uring.
>
> Like openat*(), this tries to do a non-blocking lookup first and resorts
> to async lookup when that fails.
>
> This uses sqe->addr for the path, ->addr2 for the file handle which is
> filled in by the kernel, and ->addr3 for the mouint_id which is filled
> in by the kernel.
>
> Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
> ---
>  include/uapi/linux/io_uring.h |  1 +
>  io_uring/opdef.c              |  7 ++++++
>  io_uring/openclose.c          | 43 +++++++++++++++++++++++++++++++++++
>  io_uring/openclose.h          |  3 +++
>  4 files changed, 54 insertions(+)
>
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 6957dc539d83..596bae788b48 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -289,6 +289,7 @@ enum io_uring_op {
>         IORING_OP_READV_FIXED,
>         IORING_OP_WRITEV_FIXED,
>         IORING_OP_PIPE,
> +       IORING_OP_NAME_TO_HANDLE_AT,
>
>         /* this goes last, obviously */
>         IORING_OP_LAST,
> diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> index 9568785810d9..ff2672bbd583 100644
> --- a/io_uring/opdef.c
> +++ b/io_uring/opdef.c
> @@ -574,6 +574,10 @@ const struct io_issue_def io_issue_defs[] = {
>                 .prep                   = io_pipe_prep,
>                 .issue                  = io_pipe,
>         },
> +       [IORING_OP_NAME_TO_HANDLE_AT] = {
> +               .prep                   = io_name_to_handle_at_prep,
> +               .issue                  = io_name_to_handle_at,
> +       },
>  };
>
>  const struct io_cold_def io_cold_defs[] = {
> @@ -824,6 +828,9 @@ const struct io_cold_def io_cold_defs[] = {
>         [IORING_OP_PIPE] = {
>                 .name                   = "PIPE",
>         },
> +       [IORING_OP_NAME_TO_HANDLE_AT] = {
> +               .name                   = "NAME_TO_HANDLE_AT",
> +       },
>  };
>
>  const char *io_uring_get_opcode(u8 opcode)
> diff --git a/io_uring/openclose.c b/io_uring/openclose.c
> index d70700e5cef8..f15a9307f811 100644
> --- a/io_uring/openclose.c
> +++ b/io_uring/openclose.c
> @@ -27,6 +27,15 @@ struct io_open {
>         unsigned long                   nofile;
>  };
>
> +struct io_name_to_handle {
> +       struct file                     *file;
> +       int                             dfd;
> +       int                             open_flag;

These are not open_flags, there are handle_flags
(e.g. AT_HANDLE_FID)

> +       struct file_handle __user       *ufh;
> +       char __user                     *path;
> +       void __user                     *mount_id;
> +};
> +
>  struct io_close {
>         struct file                     *file;
>         int                             fd;
> @@ -187,6 +196,40 @@ void io_open_cleanup(struct io_kiocb *req)
>                 putname(open->filename);
>  }
>
> +int io_name_to_handle_at_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> +{
> +       struct io_name_to_handle *nh = io_kiocb_to_cmd(req, struct io_name_to_handle);
> +
> +       nh->dfd = READ_ONCE(sqe->fd);
> +       nh->open_flag = READ_ONCE(sqe->open_flags);

Please also create union member sqe->handle_flags
or name_to_handle_flags.

Thanks,
Amir.