[PATCH v4 2/5] block: add partition parser for U-Boot uImage.FIT

[Matthew Wilcox]

On Tue, Nov 08, 2022 at 11:03:16PM +0000, Daniel Golle wrote:
> +	/* map first page */
> +	page = read_mapping_page(
> +		mapping, fit_start_sector >> (PAGE_SHIFT - SECTOR_SHIFT), NULL);
> +
> +	if (IS_ERR(page))
> +		return -EFAULT;
> +
> +	if (PageError(page))
> +		return -EFAULT;

Why are you checking for PageError?  You won't ever get a page with an
error back from read_mapping_page().  And you have the real error in
'page', so why return -EFAUlT, which would indicate a problem copying
from the user.  Also, this is a great place to use the new folio APIs
instead of the old page APIs.  So:

	folio = read_mapping_folio(mapping,
			fit_start_sector >> PAGE_SECTORS_SHIFT, NULL);
	if (IS_ERR(folio))
		return PTR_ERR(folio);

> +	init_fit = page_address(page);

	init_fit = folio_address(folio) +
			offset_in_folio(folio, fit_start_sector * SECTOR_SIZE);

> +	if (!init_fit) {
> +		put_page(page);
> +		return -EFAULT;
> +	}

page_address() or folio_address() can't ever return NULL, you should
just drop this nonsense check.

... actually, why can't you call read_part_sector() and avoid all of
this?