From: "Martin K. Petersen" <martin.petersen@oracle.com>
Subject: Re: [PATCH] scsi:storvsc enable reading from VPD pages on SPC-2
Date: Thu, 11 Dec 2014 22:03:44 -0500
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 (Long Li's message of "Wed, 10 Dec 2014 22:28:07 +0000")
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Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>, "Martin K. Petersen" <martin.petersen@oracle.com>, Haiyang Zhang <haiyangz@microsoft.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "JBottomley@parallels.com" <JBottomley@parallels.com>, "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>
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>>>>> "Long" == Long Li <longli@microsoft.com> writes:

>> Handle the issues or handle WRITE SAME(10/16)?

Long> With this patch, the SCSI layer will be able to correctly send
Long> WRITE_SAME_16 to the Hyper-V host. It will not send WRITE_SAME_10:
Long> it has been disabled in the driver template. Do you want me to
Long> send another patch with these details?

no_write_same prevents us from attempting to use WRITE SAME(10/16) to
zero block ranges.

This is completely orthogonal to using the WRITE SAME(10/16) commands
with the UNMAP bit set to discard block ranges. The latter is controlled
by the logical block provisioning heuristics and is not affected by
no_write_same at all.

-- 
Martin K. Petersen	Oracle Linux Engineering