From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 6/6] sd: Update thin provisioning support
Date: Fri, 20 Aug 2010 11:00:40 +0200
Message-ID: <20100820090039.GD27033@lst.de>
References: <1282232941-9910-1-git-send-email-martin.petersen@oracle.com> <1282232941-9910-7-git-send-email-martin.petersen@oracle.com>
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To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, hch@lst.de

On Thu, Aug 19, 2010 at 11:49:01AM -0400, Martin K. Petersen wrote:
> +		if (sdkp->tpu && desc_count && lba_count)
> +			sdkp->unmap = 1;
> +		else if (!sdkp->tpws) {
> +			sd_printk(KERN_ERR, sdkp, "Thin provisioning is "  \
> +				  "enabled but neither TPU, nor TPWS are " \
> +				  "set. Disabling discard!\n");
> +			goto out;
> +		}
> +

I don't think we can simply break all existing setups with support for
earlier SBC drafts.  I think we should use the TPU and TPWS same bits
if present and else fall back to our current heuristics.