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

[Yu Kuai]

Hi,

在 2025/08/12 16:37, Christoph Hellwig 写道:
> 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

This looks good, it's better to refactor a bit before switch to getattr,
and I agree still return 0 on failue is fine.

Thanks,
Kuai

> .