Re: [PATCH v2 8/8] vfs: remove redundant checks from generic_remap_checks()

Darrick J. Wong
2019-05-28T16:39:33Z

On Sun, May 26, 2019 at 09:10:59AM +0300, Amir Goldstein wrote:
> The access limit checks on input file range in generic_remap_checks()
> are redundant because the input file size is guarantied to be within

guaranteed ^^^^^^^^^^

> limits and pos+len are already checked to be within input file size.
>
> Beyond the fact that the check cannot fail, if it would have failed,
> it could return -EFBIG for input file range error. There is no precedent
> for that. -EFBIG is returned in syscalls that would change file length.
>
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
> mm/filemap.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 1852fbf08eeb..7e1aa36d57a2 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3000,10 +3000,6 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in,
> return -EINVAL;
> count = min(count, size_in - (uint64_t)pos_in);
>
> - ret = generic_access_check_limits(file_in, pos_in, &count);

I suspect you could fold generic_access_check_limits into its only
caller, then...

--D

> - if (ret)
> - return ret;
> -
> ret = generic_write_check_limits(file_out, pos_out, &count);
> if (ret)
> return ret;
> --
> 2.17.1
>