Re: [PATCH 1/4] block: export part_in_flight()

[Christoph Hellwig <hch@infradead.org>]

On Mon, Apr 14, 2025 at 02:48:23PM +0800, Yu Kuai wrote:
> > If we export this it needs a kerneldoc comment, and probably also
> > a better name.
> 
> Sure about comment.

I think a name like bdev_count_inflight might also be helpful as there
is nothing partition-specific in the helper.

> There are two kinds of helpers:
> 
> 1) part_in_flight and part_in_flight_rw
> 2) blk_mq_in_flight and blk_mq_in_flight_rw
> 
> 1) is accounted at blk_account_io_start(), while 2) is
> blk_mq_start_request(), I think this is the essential difference.
> 
> part_in_flight_rw() and blk_mq_in_flight_rw() is also used in sysfs API
> inflight for bio/rq based device. And commit 7be835694dae ("block: fix
> that util can be greater than 100%") convert blk_mq_in_flight() to
> part_in_flight() from disk stats API. Now I just checked there is no use
> for blk_mq_in_flight() anymore and maybe it can be removed.

Yeah.  I'm still confused about having the different methods to count
the _rw vs non-_rw variants for blk-mq, but I guess that's not really
in scope for your series.