Re: [PATCH v2] loop: use vfs_getattr_nosec() for accurate file size

[Christoph Hellwig <hch@infradead.org>]

On Tue, Aug 12, 2025 at 02:17:01PM +0900, Damien Le Moal wrote:
> And indeed, that:
> 
> 	/* size of the new backing store needs to be the same */
>         if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
>                 goto out_err;
> 
> Will need some massaging.

Why?  get_loop_size just derives the first arguments to get_size
from the passed in loop device in the same way the only other caller
to get_size does.  So we can just:

  1) convert loop_set_status to use get_loop_size
  2) Fold get_size into get_loop_size
  3) Maye rename get_size to lo_calculate_size to have a descriptive
     name while we're touching it?
  4) switch to vfs_getattr