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

[Mike Christie <michaelc cs wisc edu>]

Mike Christie wrote:
> 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.
> 

Ignore that. The problem would be that we may not want to decide which
path to use at map time.