From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keith Busch <keith.busch@intel.com>
Subject: Re: [PATCH] sd: dif sector calculation
Date: Fri, 20 Sep 2013 16:52:06 -0600 (MDT)
Message-ID: <alpine.LRH.2.03.1309201647220.31457@AMR>
References: <1379475143-2792-1-git-send-email-keith.busch@intel.com> <yq1ob7ndt0w.fsf@sermon.lab.mkp.net>
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To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Keith Busch <keith.busch@intel.com>, linux-scsi@vger.kernel.org, "James E.J. Bottomley" <JBottomley@parallels.com>, Ric Wheeler <rwheeler@redhat.com>

On Fri, 20 Sep 2013, Martin K. Petersen wrote:

>>>>>> "Keith" == Keith Busch <keith.busch@intel.com> writes:
>
> Keith> The ref tag should be the device's physical LBA rather than the
> Keith> 512 byte bio sector.
>
> The bip sector is just a seed value set by the application. It is not
> correct to scale it based on sector size or PI interval.

If I follow the current implementation correctly and have a 4k physical
block size, a two block write at LBA 0 will generate ref tags 0 and 1
for that operation. If I read back one block at LBA 1, the current code
will expect the ref tag to be 8, but come back as 1, failing the compare.