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Date: Sat, 24 Aug 2024 10:52:45 +0200
From: Christoph Hellwig <hch@lst.de>
To: Anuj Gupta <anuj20.g@samsung.com>
Cc: axboe@kernel.dk, hch@lst.de, kbusch@kernel.org,
	martin.petersen@oracle.com, asml.silence@gmail.com, krisman@suse.de,
	io-uring@vger.kernel.org, linux-nvme@lists.infradead.org,
	linux-block@vger.kernel.org, gost.dev@samsung.com,
	linux-scsi@vger.kernel.org
Subject: Re: [PATCH v3 10/10] scsi: add support for user-meta interface
Message-ID: <20240824085245.GI8805@lst.de>
References: <20240823103811.2421-1-anuj20.g@samsung.com> <CGME20240823104639epcas5p11dbab393122841419368a86b4bd5c04b@epcas5p1.samsung.com> <20240823103811.2421-12-anuj20.g@samsung.com>
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In-Reply-To: <20240823103811.2421-12-anuj20.g@samsung.com>
User-Agent: Mutt/1.5.17 (2007-11-01)

> Add support for sending user-meta buffer. Set tags to be checked
> using flags specified by user/block-layer user and underlying DIF/DIX
> configuration. Introduce BLK_INTEGRITY_APP_TAG to specify apptag.
> This provides a way for upper layers to specify apptag checking.

We'll also need that flag for nvme, don't we?  It should also be
added in a block layer patch and not as part of a driver patch.

> +/*
> + * Can't check reftag alone or apptag alone
> + */
> +static bool sd_prot_flags_valid(struct scsi_cmnd *scmd)
> +{
> +	struct request *rq = scsi_cmd_to_rq(scmd);
> +	struct bio *bio = rq->bio;
> +
> +	if (bio_integrity_flagged(bio, BIP_CHECK_REFTAG) &&
> +	    !bio_integrity_flagged(bio, BIP_CHECK_APPTAG))
> +		return false;
> +	if (!bio_integrity_flagged(bio, BIP_CHECK_REFTAG) &&
> +	    bio_integrity_flagged(bio, BIP_CHECK_APPTAG))
> +		return false;
> +	return true;
> +}

We'll need to advertise this limitations to the application or in-kernel
user somehow..

> +		if ((bio_integrity_flagged(bio, BIP_CTRL_NOCHECK) == false) &&
> +			(!dix || bio_integrity_flagged(bio, BIP_CHECK_REFTAG)))

Incorrect formatting.  This is better:

		if (!bio_integrity_flagged(bio, BIP_CTRL_NOCHECK) &&
		    (!dix || bio_integrity_flagged(bio, BIP_CHECK_REFTAG)))