From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 1/4] target: Add target_submit_cmd_map_mem for SGL fabric
 memory passthrough
Date: Tue, 2 Oct 2012 11:17:52 -0400
Message-ID: <20121002151752.GA21786@infradead.org>
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To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: target-devel <target-devel@vger.kernel.org>, linux-scsi <linux-scsi@vger.kernel.org>, Christoph Hellwig <hch@lst.de>, Paolo Bonzini <pbonzini@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>

On Tue, Oct 02, 2012 at 07:15:44AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> This patch adds a new TARGET_SCF_MAP_MEM flag within __target_submit_cmd()
> + a target_submit_cmd_map_mem() wrapper to pass pre-allocated SGL memory
> using existing transport_generic_map_mem_to_cmd() logic into the generic
> target submit I/O codepath.

Instead of requiring a flag we could simply check for the sglist_count
to be non-zero instead of requiring multiple pieces of information to
be in sync.

I'd also be tempted to remove the wrappers and just expose what is
__target_submit_cmd now to the drivers, but that can be done
independently as a cleanup.