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Date: Mon, 29 Jul 2024 19:03:08 +0200
From: Christoph Hellwig <hch@lst.de>
To: Anuj Gupta <anuj20.g@samsung.com>
Cc: Christoph Hellwig <hch@lst.de>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Kanchan Joshi <joshi.k@samsung.com>, linux-block@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org
Subject: Re: fine-grained PI control
Message-ID: <20240729170308.GA31298@lst.de>
References: <20240705083205.2111277-1-hch@lst.de> <yq1ttgz5l6d.fsf@ca-mkp.ca.oracle.com> <CGME20240709071611epcas5p1c5f2b59325d562658522842f89a31861@epcas5p1.samsung.com> <20240709071604.GB18993@lst.de> <20240726102156.GA17572@green245>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Jul 26, 2024 at 03:51:56PM +0530, Anuj Gupta wrote:
> 
> I was thinking something like below patch[*] could help us get rid of the
> BIP_USER_CHECK_FOO flags, and also driver can now check flags passed by block
> layer instead of checking if it's user passthrough data. Haven't plumbed the
> scsi side of things, but do you think it can work with scsi? 
> 
> Subject: [PATCH] block: introduce BIP_CHECK_GUARD/REFTAG/APPTAG bip_flags
> 
> This patch introduces BIP_CHECK_GUARD/REFTAG/APPTAG bip_flags which
> indicate how the hardware should check the payload. The driver can now
> just rely on block layer flags, and doesn't need to know the integrity
> source. Submitter of PI chooses which tags to check. This would also
> give us a unified interface for user and kernel generated integrity.

This looks reasonably to me for the in-kernel interface.  We'll still
need to deal with the fact that SCSI is a bit selective in what
combination of these flags it actually allows.