Re: [PATCH 2/5] block: add request->io_data_len

[Tejun Heo]

On Thu, Apr 09, 2020 at 09:44:06AM +0800, Ming Lei wrote:
> Almost all __blk_mq_end_request() follow blk_update_request(), so the
> completed bytes can be passed to __blk_mq_end_request(), then we can
> avoid to introduce this field.

But on some drivers blk_update_request() may be called multiple times before
__blk_mq_end_request() is called and what's needed here is the total number of
bytes in the whole request, not just in the final completion.

> Also there is just 20 callers of __blk_mq_end_request(), looks this kind
> of change shouldn't be too big.

This would work iff we get rid of partial completions and if we get rid of
partial completions, we might as well stop exposing blk_update_request() and
__blk_mq_end_request().

Thanks.

-- 
tejun