Re: [PATCH] block: fail unaligned bio from submit_bio_noacct()

[Bart Van Assche <bvanassche@xxxxxxx>]

On 3/21/24 06:16, Ming Lei wrote:
> +static bool bio_check_alignment(struct bio *bio, struct request_queue *q)
> +{
> +	unsigned int bs = q->limits.logical_block_size;
> +	unsigned int size = bio->bi_iter.bi_size;
> +
> +	if (size & (bs - 1))
> +		return false;
> +
> +	if (size && ((bio->bi_iter.bi_sector << SECTOR_SHIFT) & (bs - 1)))
> +		return false;
Why "size &&"? It doesn't harm to reject unaligned bios if size == 0 and
it will reduce the number of if-tests in the hot path.

Why to shift bio->bi_iter.bi_sector left instead of shifting (bs - 1)
right?

Thanks,

Bart.