Re: [dm-devel] Re: [RFC PATCH 1/8] rqbased-dm: allow blk_get_request() to be called from interrupt context

Mike Christie
2006-12-21T18:31:15Z

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.