Re: [PATCH v3 3/9] vfs: add tmpfile_open() helper

[Miklos Szeredi <miklos@szeredi.hu>]

On Wed, 21 Sept 2022 at 10:09, Christian Brauner <brauner@kernel.org> wrote:
>
> Feels like this could be simplified while being equally legible to
> something like:
>
> /**
>  * tmpfile_open - open a tmpfile for kernel internal use
>  * @mnt_userns: user namespace of the mount the inode was found from
>  * @parentpath: path of the base directory
>  * @mode:       mode of the new tmpfile
>  * @open_flag:  flags
>  * @cred:       credentials for open
>  *
>  * Create and open a temporary file.  The file is not accounted in nr_files,
>  * hence this is only for kernel internal use, and must not be installed into
>  * file tables or such.
>  *
>  * The helper relies on the "noaccount" property of open_with_fake_path().
>  * Otherwise it is equivalent to dentry_open().
>  *
>  * Return: Opened tmpfile on success, error pointer on failure.
>  */
> struct file *tmpfile_open(struct user_namespace *mnt_userns,
>                           const struct path *parentpath,
>                           umode_t mode, int open_flag, const struct cred *cred)
> {
>         struct file *file;
>         int error;
>         struct path path = { .mnt = parentpath->mnt };
>
>         path.dentry = vfs_tmpfile(mnt_userns, parentpath->dentry, mode, open_flag);
>         if (IS_ERR(path.dentry))
>                 return ERR_CAST(path.dentry);
>
>         error = may_open(mnt_userns, &path, 0, open_flag);
>         if (!error)
>                 file = open_with_fake_path(&path, open_flag, d_inode(path.dentry), cred);
>         else
>                 file = ERR_PTR(error);
>         dput(path.dentry);
>         return file;
> }
> EXPORT_SYMBOL(tmpfile_open);

Okay, but this code gets completely rewritten in 7/9, so maybe not
worth bothering about.

Thanks,
Miklos