Date: Tue, 12 May 2015 00:21:53 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Matias Bj?rling <m@bjorling.me>
Cc: Christoph Hellwig <hch@infradead.org>, axboe@fb.com,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvme@lists.infradead.org, keith.busch@intel.com,
        javier@paletta.io
Subject: Re: [PATCH v3 1/7] bio: Introduce LightNVM payload
Message-ID: <20150512072153.GA25438@infradead.org>
References: <1429712816-10336-1-git-send-email-m@bjorling.me>
 <1429712816-10336-2-git-send-email-m@bjorling.me>
 <20150509160007.GA16058@infradead.org>
 <5550997B.1000609@bjorling.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5550997B.1000609@bjorling.me>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 911
Lines: 17

On Mon, May 11, 2015 at 01:58:51PM +0200, Matias Bj?rling wrote:
> >Can you explain why this needs to be done on a per-bio instead of a
> >per-request level?  I don't really think a low-level driver should add
> >fields to struct bio as that can be easily remapped.
> 
> When a bio is submitted through the block layer, it can be merged/splitted
> on going through the block layer. Thus, we don't know the number of physical
> addresses that must be mapped before its on the other side.

For any sort of passthrough bios that should not be the case.  It's not
for BLOCK_PC, it's not for my new pass through NVMe commands and I don't
think it should be in this case.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/