Re: [PATCH 4/6] fhandle: create __do_handle_open() helper

[Amir Goldstein <amir73il@gmail.com>]

On Fri, Aug 15, 2025 at 1:52 AM Thomas Bertschinger
<tahbertschinger@gmail.com> wrote:
>
> do_handle_open() takes care of both opening a file via its file handle,
> and associating it with a file descriptor.
>
> For io_uring, it is useful to do just the opening part separately,
> because io_uring might not want to install it into the main open files
> table when using fixed descriptors.
>
> This creates a helper which will enable io_uring to do that.
>
> Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
> ---
>  fs/fhandle.c  | 24 +++++++++++++++++-------
>  fs/internal.h |  2 ++
>  2 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/fs/fhandle.c b/fs/fhandle.c
> index dbb273a26214..b14884a93867 100644
> --- a/fs/fhandle.c
> +++ b/fs/fhandle.c
> @@ -397,8 +397,8 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
>         return retval;
>  }
>
> -static long do_handle_open(int mountdirfd, struct file_handle __user *ufh,
> -                          int open_flag)
> +struct file *__do_handle_open(int mountdirfd, struct file_handle __user *ufh,
> +                             int open_flag)
>  {
>         long retval = 0;
>         struct path path __free(path_put) = {};
> @@ -407,17 +407,27 @@ static long do_handle_open(int mountdirfd, struct file_handle __user *ufh,
>
>         retval = handle_to_path(mountdirfd, ufh, &path, open_flag);
>         if (retval)
> -               return retval;
> -
> -       CLASS(get_unused_fd, fd)(open_flag);
> -       if (fd < 0)
> -               return fd;
> +               return ERR_PTR(retval);
>
>         eops = path.mnt->mnt_sb->s_export_op;
>         if (eops->open)
>                 file = eops->open(&path, open_flag);
>         else
>                 file = file_open_root(&path, "", open_flag, 0);
> +
> +       return file;
> +}
> +
> +static long do_handle_open(int mountdirfd, struct file_handle __user *ufh,
> +                          int open_flag)
> +{
> +       struct file *file;
> +
> +       CLASS(get_unused_fd, fd)(open_flag);
> +       if (fd < 0)
> +               return fd;
> +
> +       file = __do_handle_open(mountdirfd, ufh, open_flag);
>         if (IS_ERR(file))
>                 return PTR_ERR(file);
>
> diff --git a/fs/internal.h b/fs/internal.h
> index af7e0810a90d..26ac6f356313 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -362,3 +362,5 @@ void pidfs_get_root(struct path *path);
>  long do_name_to_handle_at(int dfd, const char __user *name,
>                           struct file_handle __user *handle,
>                           void __user *mnt_id, int flag, int lookup_flags);
> +struct file *__do_handle_open(int mountdirfd, struct file_handle __user *ufh,
> +                             int open_flag);

As I said I displike exported do_XXX() helpers, but I __do_XXX() exported
helpers are much worse.

How about do_filp_handle_open()?

Thanks,
Amir.