Re: [PATCH 2/4] dm crypt: Fix zoned block device support

[Johannes Thumshirn <Johannes.Thumshirn@wdc.com>]

On 16/04/2021 05:05, Damien Le Moal wrote:

[...]

> +	CRYPT_IV_NO_SECTORS,		/* IV calculation does not use sectors */

[...]

> -	if (ivmode == NULL)
> +	if (ivmode == NULL) {
>  		cc->iv_gen_ops = NULL;
> -	else if (strcmp(ivmode, "plain") == 0)
> +		set_bit(CRYPT_IV_NO_SECTORS, &cc->cipher_flags);
> +	} else if (strcmp(ivmode, "plain") == 0)

[...]

> +		if (!test_bit(CRYPT_IV_NO_SECTORS, &cc->cipher_flags)) {
> +			DMWARN("Zone append is not supported with sector-based IV cyphers");
> +			ti->zone_append_not_supported = true;
> +		}

I think this negation is hard to follow, at least I had a hard time
reviewing it.

Wouldn't it make more sense to use CRYPT_IV_USE_SECTORS, set the bit
for algorithms that use sectors as IV (like plain64) and then do a 
normal

	if (test_bit(CRYPT_IV_USE_SECTORS, &cc->cipher_flags)) {
		DMWARN("Zone append is not supported with sector-based IV cyphers");
		ti->zone_append_not_supported = true;
	}

i.e. without the double negation?