On Thu, Dec 21, 2023 at 11:54:10AM +0200, Amir Goldstein wrote:
> Assert that the file object is allocated in a backing_file container
> so that file_user_path() could be used to display the user path and
> not the backing file's path in /proc/<pid>/maps.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/backing-file.c | 27 +++++++++++++++++++++++++++
> fs/overlayfs/file.c | 23 ++++++-----------------
> include/linux/backing-file.h | 2 ++
> 3 files changed, 35 insertions(+), 17 deletions(-)
>
> diff --git a/fs/backing-file.c b/fs/backing-file.c
> index 46488de821a2..1ad8c252ec8d 100644
> --- a/fs/backing-file.c
> +++ b/fs/backing-file.c
> @@ -11,6 +11,7 @@
> #include <linux/fs.h>
> #include <linux/backing-file.h>
> #include <linux/splice.h>
> +#include <linux/mm.h>
>
> #include "internal.h"
>
> @@ -284,6 +285,32 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
> }
> EXPORT_SYMBOL_GPL(backing_file_splice_write);
>
> +int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
> + struct backing_file_ctx *ctx)
> +{
> + const struct cred *old_cred;
> + int ret;
> +
> + if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) ||
Couldn't that WARN_ON_ONCE() be in every one of these helpers in this
series? IOW, when would you ever want to use a backing_file_*() helper
on a non-backing file?
