Message-ID: <49D3699F.4030105@kernel.org>
Date: Wed, 01 Apr 2009 22:18:23 +0900
From: Tejun Heo <tj@kernel.org>
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To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
CC: axboe@kernel.dk, bharrosh@panasas.com, linux-kernel@vger.kernel.org,
       tj@kenel.org
Subject: Re: [PATCH 8/8] blk-map: reimplement blk_rq_map_user() using blk_rq_map_user_iov()
References: <49D36329.20004@kernel.org>	<20090401215933S.fujita.tomonori@lab.ntt.co.jp>	<49D3662B.3000801@kernel.org> <20090401221102O.fujita.tomonori@lab.ntt.co.jp> <49D36951.9000604@kernel.org>
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Tejun Heo wrote:
>>> reason blk_rq_map_user() had multiple bio chaining was to work around
>>> BIO_MAX_SIZE.  blk_rq_map_user_iov() doesn't support multiple bio
>>> chaining, so sans blk_rq_append_bio() or playing with rq/bio internals
>>> directly, there's no way to use or even know about multiple bios.
>> Yes, only non iovec interface of SG_IO supports large data
>> transfer. Users have been lived with that.
> 
> This patch doesn't remove any feature.  You don't lose anything.  What
> used to be done with multiple bios is now done with single bio.  The
> implementation is simpler and shorter.  Using or not using multiple
> bios doesn't (and shouldn't) make any difference to blk_map_*() users.

Oh.. and blk_rq_map_user_iov() now gets to play with large requests
too.  :-)

-- 
tejun
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