From mboxrd@z Thu Jan  1 00:00:00 1970
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Subject: Re: [PATCH 1/2] block: move the padding adjustment to blk_rq_map_sg
Date: Mon, 7 Apr 2008 22:11:05 +0900
Message-ID: <20080407221103Y.tomof@acm.org>
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On Mon, 07 Apr 2008 20:31:38 +0900
Tejun Heo <htejun@gmail.com> wrote:

> FUJITA Tomonori wrote:
> >> Maybe we need yet another flag indicating padding space
> >> availability?
> > 
> > How about doing the exact same thing that the drain buffer does? We
> > can put pre-allocated buffer to a queue and save one sg entry for it.
> 
> Each sg entry should be aligned so extra sg doesn't really help or am I 
> missing something?

Sorry, please scratch the previous mail. I think that I misunderstood
what you meant.

The current code does padding only for requests that we call
__blk_rq_map_user (bio_copy_user) for. You meant that if we create a
new flag like REQ_NEED_PADDING and set it in blk_rq_map_user,
blk_rq_map_sg can do padding only when it was set.

Right?