[dm-devel] [PATCH v2 4/4] brd: implement secure erase and write zeroes

[Chaitanya Kulkarni]

>   /*
> @@ -300,23 +303,34 @@ out:
>   
>   void brd_do_discard(struct brd_device *brd, struct bio *bio)
>   {
> -	sector_t sector, len, front_pad;
> +	bool zero_padding;
> +	sector_t sector, len, front_pad, end_pad;
>   
>   	if (unlikely(!discard)) {
>   		bio->bi_status = BLK_STS_NOTSUPP;
>   		return;
>   	}
>   
> +	zero_padding = bio_op(bio) == REQ_OP_SECURE_ERASE || bio_op(bio) == REQ_OP_WRITE_ZEROES;
>   	sector = bio->bi_iter.bi_sector;
>   	len = bio_sectors(bio);
>   	front_pad = -sector & (PAGE_SECTORS - 1);
> +
> +	if (zero_padding && unlikely(front_pad != 0))
> +		copy_to_brd(brd, page_address(ZERO_PAGE(0)), sector, min(len, front_pad) << SECTOR_SHIFT);
> +
>   	sector += front_pad;
>   	if (unlikely(len <= front_pad))
>   		return;
>   	len -= front_pad;
> -	len = round_down(len, PAGE_SECTORS);
> +
> +	end_pad = len & (PAGE_SECTORS - 1);
> +	if (zero_padding && unlikely(end_pad != 0))
> +		copy_to_brd(brd, page_address(ZERO_PAGE(0)), sector + len - end_pad, end_pad << SECTOR_SHIFT);
> +	len -= end_pad;
> +
>
Is it possible to avoid these long lines ?

-ck