Re: [PATCH 03/14] block: implement blk_rq_map_kern_prealloc()

[Tejun Heo <htejun@gmail.com>]

Hello,

A few issues.

Tejun Heo wrote:
>> Perhaps you could reorder the code below a bit?
>>
>> My proposal is:
>> * blk_rq_map_kern_prealloc => is simplified to be
>>     int blk_rq_map_bio(struct request_queue *q, struct request *rq,
>> 		       struct bio *bio);

The thing is that the prealloc variant should be allowed to be called
from IRQ context and blk_queue_bounce() shouldn't be called.
Hmmm... well, the caller is supposed to know what it's doing and maybe
we can just add a comment that it shouldn't be called with buffers
which might get bounced from IRQ context.

>> * The extra checks currently inside blk_rq_map_kern_prealloc are moved
>>   to bio_map_kern_prealloc()
>>
>> * Users call bio_map_kern_prealloc() directly and then use blk_rq_map_bio()
>>   in a two stage process.

This breaks consistency with blk_rq_map_*() family of functions.  Do
you have a plan to make them all consistent?  I think we really need
to maintain API consistency.

Thanks.

-- 
tejun