Re: [PATCH v2 1/2] fs: make do_mkdirat() take struct filename

[Dmitry Kadashev <dkadashev@gmail.com>]

On Tue, Feb 2, 2021 at 3:25 PM Dmitry Kadashev <dkadashev@gmail.com> wrote:
>
> Pass in the struct filename pointers instead of the user string, and
> update the three callers to do the same. This is heavily based on
> commit dbea8d345177 ("fs: make do_renameat2() take struct filename").
>
> This behaves like do_unlinkat() and do_renameat2().
>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
> ---
>  fs/internal.h |  1 +
>  fs/namei.c    | 25 +++++++++++++++++++------
>  2 files changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index c6c85f6ad598..b10005dfaa48 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -76,6 +76,7 @@ long do_unlinkat(int dfd, struct filename *name);
>  int may_linkat(struct path *link);
>  int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
>                  struct filename *newname, unsigned int flags);
> +long do_mkdirat(int dfd, struct filename *name, umode_t mode);
>
>  /*
>   * namespace.c
> diff --git a/fs/namei.c b/fs/namei.c
> index 4cae88733a5c..3657bdf1aafc 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3431,7 +3431,7 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
>         return file;
>  }
>
> -static struct dentry *filename_create(int dfd, struct filename *name,
> +static struct dentry *__filename_create(int dfd, struct filename *name,
>                                 struct path *path, unsigned int lookup_flags)
>  {
>         struct dentry *dentry = ERR_PTR(-EEXIST);
> @@ -3487,7 +3487,6 @@ static struct dentry *filename_create(int dfd, struct filename *name,
>                 error = err2;
>                 goto fail;
>         }
> -       putname(name);
>         return dentry;
>  fail:
>         dput(dentry);
> @@ -3502,6 +3501,16 @@ static struct dentry *filename_create(int dfd, struct filename *name,
>         return dentry;
>  }
>
> +static inline struct dentry *filename_create(int dfd, struct filename *name,
> +                               struct path *path, unsigned int lookup_flags)
> +{
> +       struct dentry *res = __filename_create(dfd, name, path, lookup_flags);
> +
> +       if (!IS_ERR(res))
> +               putname(name);
> +       return res;
> +}
> +
>  struct dentry *kern_path_create(int dfd, const char *pathname,
>                                 struct path *path, unsigned int lookup_flags)
>  {
> @@ -3654,15 +3663,18 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
>  }
>  EXPORT_SYMBOL(vfs_mkdir);
>
> -static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
> +long do_mkdirat(int dfd, struct filename *name, umode_t mode)
>  {
>         struct dentry *dentry;
>         struct path path;
>         int error;
>         unsigned int lookup_flags = LOOKUP_DIRECTORY;
>
> +       if (IS_ERR(name))
> +               return PTR_ERR(name);
> +
>  retry:
> -       dentry = user_path_create(dfd, pathname, &path, lookup_flags);
> +       dentry = __filename_create(dfd, name, &path, lookup_flags);
>         if (IS_ERR(dentry))
>                 return PTR_ERR(dentry);
>
> @@ -3676,17 +3688,18 @@ static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
>                 lookup_flags |= LOOKUP_REVAL;
>                 goto retry;
>         }
> +       putname(name);
>         return error;
>  }
>
>  SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
>  {
> -       return do_mkdirat(dfd, pathname, mode);
> +       return do_mkdirat(dfd, getname(pathname), mode);
>  }
>
>  SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
>  {
> -       return do_mkdirat(AT_FDCWD, pathname, mode);
> +       return do_mkdirat(AT_FDCWD, getname(pathname), mode);
>  }
>
>  int vfs_rmdir(struct inode *dir, struct dentry *dentry)
> --
> 2.30.0

Hi Al,

Are you OK with this version?

-- 
Dmitry Kadashev