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Subject: Re: [PATCH 1/2] block: add bi_crypto_ctx variable in struct bio
To:     Parshuram Thombare <pthombar@cadence.com>, tj@kernel.org,
        jbacik@fb.com, michaelcallahan@fb.com, snitzer@redhat.com,
        osandov@fb.com, keith.busch@intel.com, ming.lei@redhat.com,
        shli@fb.com, dennisszhou@gmail.com, linux-kernel@vger.kernel.org
Cc:     adouglas@cadence.com, jank@cadence.com, rafalc@cadence.com
References: <20181211095001.GA32573@lvlogina.cadence.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <62281c61-de73-a0a3-2ea2-eeea81778eea@kernel.dk>
Date:   Tue, 11 Dec 2018 06:37:04 -0700
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On 12/11/18 2:50 AM, Parshuram Thombare wrote:
> Add variable 'void *bi_crypt_ctx' in 'struct bio'. This will
> be used to associate bio with crypto configuration of controller
> supporting real time / inline encryption/decryption.
> 
> Signed-off-by: Parshuram Thombare <pthombar@cadence.com>
> ---
>  include/linux/blk_types.h |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 1dcf652..bd77603 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -188,6 +188,10 @@ struct bio {
>  #endif
>  	};
>  
> +#ifdef CONFIG_BLK_DEV_HW_RT_ENCRYPTION
> +	void *bi_crypto_ctx;
> +#endif
> +
>  	unsigned short		bi_vcnt;	/* how many bio_vec's */
>  
>  	/*

Pretty sure I mentioned this last time, but in case I didn't, don't
add bio members for random drivers. Can you imagine how huge
this thing would be if we allowed that?

If you need per-io storage, put it in the payload for the blk-mq
request. That way you are only bloating your own IO related data
structures, not everyones.

-- 
Jens Axboe