Re: [PATCH v7 05/43] blk-crypto: add a process bio callback

[Eric Biggers <ebiggers@kernel.org>]

On Wed, May 13, 2026 at 10:52:39AM +0200, Daniel Vacek wrote:
> @@ -330,6 +330,17 @@ static void __blk_crypto_fallback_encrypt_bio(struct bio *src_bio,
>  		}
>  	}
>  
> +	/* Process the encrypted bio before we submit it. */
> +	if (bc->bc_key->crypto_cfg.process_bio) {
> +		blk_status_t status;
> +
> +		status = bc->bc_key->crypto_cfg.process_bio(src_bio, enc_bio);
> +		if (status != BLK_STS_OK) {
> +			enc_bio->bi_status = status;
> +			goto out_free_enc_bio;
> +		}
> +	}

This looks very out of place in this function, because this function
potentially submits multiple encrypted bios whereas this code assumes
there's just one.  I think we could at least use a comment here, as well
as a WARN_ON_ONCE(!bc->bc_key->crypto_cfg.process_bio) in the case where
an additional bio is being submitted.

> +	/*
> +	 * We cannot split bio's that have process_bio, as they require the original bio.
> +	 * The upper layer must make sure to limit the submitted bio's appropriately.
> +	 */
> +	if (bio_segments(src_bio) > BIO_MAX_VECS && bc->bc_key->crypto_cfg.process_bio) {

Checks should be reversed so that the expensive bio_segments() check
only gets done if process_bio is non-NULL.

(Sashiko spotted this too, by the way)

> + * @process_bio: the call back if the upper layer needs to process the encrypted
> + *		 bio

or NULL if no such callback is needed.

> + * @proces_bio: optional callback to process encrypted bios.

Typo.

By the way, after writing kerneldoc you should run the kerneldoc
checker, as it will find things like this:

$ scripts/kernel-doc -v -none include/linux/blk-crypto.h 
Info: include/linux/blk-crypto.h:79 Scanning doc for struct blk_crypto_config
Warning: include/linux/blk-crypto.h:95 struct member 'process_bio' not described in 'blk_crypto_config'