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From:   John Garry <john.garry@huawei.com>
Subject: Question on t10_pi_ref_tag()
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Date:   Fri, 14 Dec 2018 12:04:54 +0000
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Hi,

I have a question on this function in the $subject.

In https://marc.info/?l=linux-kernel&m=154466776014573&w=2, Martin 
recommended using this function.

However, for our driver, we find it returns 0 always, as 
rq->q->integrity.interval_exp = 0.

Our host is advertised DIF capable only. I assume that interval_exp 
would be set somehow from 
sd_dif_config_host()->blk_integrity_register(), but we don't follow this 
path for !DIX.

What would we be missing that this is unset?

Thanks,
John