Re: [PATCH 2/3] mm/swap: use swap_ops to register swap device's methods

[YoungJun Park <youngjun.park@lge.com>]

On Mon, Mar 02, 2026 at 06:40:15PM +0800, Baoquan He wrote:

Hello Baoquan!

...
> +	.read_folio = swap_read_folio_bdev_sync,
> +	.write_folio = swap_writepage_bdev_sync,
> +};
> +
> +static struct swap_ops bdev_async_swap_ops = {
> +	.read_folio = swap_read_folio_bdev_async,
> +	.write_folio = swap_writepage_bdev_async,
> +};
> +
> +int probe_swap_fs(struct swap_info_struct *sis)
> +{
> +	/*
> +	 * ->flags can be updated non-atomically (scan_swap_map_slots),
> +	 * but that will never affect SWP_FS_OPS, so the data_race
> +	 * is safe.
> +	 */
> +	if (data_race(sis->flags & SWP_FS_OPS))
> +		sis->ops = &bdev_fs_swap_ops;
> +	/*
> +	 * ->flags can be updated non-atomically (scan_swap_map_slots),
> +	 * but that will never affect SWP_SYNCHRONOUS_IO, so the data_race
> +	 * is safe.
> +	 */

The reference to scan_swap_map_slots appears to be outdated as the
function no longer exists in the current codebase. It might be
better to update this to a more generic term?

If comments are needed to be updated, 
Similar comments in may_enter_fs likely need a similar update
for consistency.

> +	else if (data_race(sis->flags & SWP_SYNCHRONOUS_IO))
> +		sis->ops = &bdev_sync_swap_ops;
> +	else
> +		sis->ops = &bdev_async_swap_ops;
> +	return 0;

it seems return value is not needed.

Thanks 
Youngjun Park