Message-ID: <458AD2E0.40807@cs.wisc.edu>
Date: Thu, 21 Dec 2006 12:30:56 -0600
From: Mike Christie <michaelc@cs.wisc.edu>
User-Agent: Thunderbird 1.5 (X11/20060313)
MIME-Version: 1.0
To: Jens Axboe <jens.axboe@oracle.com>
CC: device-mapper development <dm-devel@redhat.com>, mchristi@redhat.com,
       linux-kernel@vger.kernel.org, agk@redhat.com
Subject: Re: [dm-devel] Re: [RFC PATCH 1/8] rqbased-dm: allow blk_get_request()
  to be called from interrupt context
References: <20061220134848.GF10535@kernel.dk> <20061220.125002.71083198.k-ueda@ct.jp.nec.com> <20061220184917.GJ10535@kernel.dk> <20061220.165549.39151582.k-ueda@ct.jp.nec.com> <20061221075305.GD17199@kernel.dk> <458ACB69.8000603@cs.wisc.edu> <458ACEB1.3030406@cs.wisc.edu> <20061221182432.GB17199@kernel.dk>
In-Reply-To: <20061221182432.GB17199@kernel.dk>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1311
Lines: 27

Jens Axboe wrote:
> On Thu, Dec 21 2006, Mike Christie wrote:
>> Or the block layer code could set up the clone too. elv_next_request
>> could prep a clone based on the orignal request for the driver then dm
>> would not have to worry about that part.
> 
> It really can't, since it doesn't know how to allocate the clone
> request. I'd rather export this functionality as helpers.
> 

What do you think about dm's plan to break up make_request into a
mapping function and in to the part the builds the bio into a request.
This would fit well with them being helpers and being able to allocate
the request from the correct context.

I see patches for that did not get posted, but I thought Joe and
Alasdair used to talk about that a lot and in the dm code I think there
is sill comments about doing it. Maybe the dm comments mentioned the
merge_fn, but I guess the merge_fn did not fit what they wanted to do or
something. I think Alasdair talked about this at one of his talks at OLS
or it was in a proposal for the kernel summit. I can dig up the mail if
you want.
-
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/