Re: [PATCH 1/3] fs: split off vfs_getdents function of getdents64 syscall

[Christian Brauner <brauner@kernel.org>]

On Tue, Jul 11, 2023 at 05:50:27PM -0600, Jens Axboe wrote:
> On 7/11/23 5:41?PM, Dave Chinner wrote:
> > On Tue, Jul 11, 2023 at 07:40:25PM +0800, Hao Xu wrote:
> >> From: Dominique Martinet <asmadeus@codewreck.org>
> >>
> >> This splits off the vfs_getdents function from the getdents64 system
> >> call.
> >> This will allow io_uring to call the vfs_getdents function.
> >>
> >> Co-developed-by: Stefan Roesch <shr@fb.com>
> >> Signed-off-by: Stefan Roesch <shr@fb.com>
> >> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
> >> ---
> >>  fs/internal.h |  8 ++++++++
> >>  fs/readdir.c  | 34 ++++++++++++++++++++++++++--------
> >>  2 files changed, 34 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/fs/internal.h b/fs/internal.h
> >> index f7a3dc111026..b1f66e52d61b 100644
> >> --- a/fs/internal.h
> >> +++ b/fs/internal.h
> >> @@ -304,3 +304,11 @@ ssize_t __kernel_write_iter(struct file *file, struct iov_iter *from, loff_t *po
> >>  struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns);
> >>  struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap);
> >>  void mnt_idmap_put(struct mnt_idmap *idmap);
> >> +
> >> +/*
> >> + * fs/readdir.c
> >> + */
> >> +struct linux_dirent64;
> >> +
> >> +int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
> >> +		 unsigned int count);
> > 
> > Uh...
> > 
> > Since when have we allowed code outside fs/ to use fs/internal.h?
> 
> io_uring does use for things like open/close, statx, and xattr already.

Arguably though because you io_uring once used to be located under fs/.
In general though, we don't support anyone outside of fs/ to use that
header.