Re: [PATCH v3 1/5] block: Optimize bio io priority setting

[Mike Snitzer]

On Mon, Dec 11 2023 at  3:59P -0500,
Hongyu Jin <hongyu.jin.cn@xxxxxxxxx> wrote:

> From: Hongyu Jin <hongyu.jin@xxxxxxxxxx>
> 
> Current call bio_set_ioprio() for each cloned bio and splited bio,
> and the io priority can't be passed to module that implement
> struct gendisk::fops::submit_bio, such as device-mapper.
> 
> Move bio_set_ioprio() into submit_bio(), only call bio_set_ioprio()
> once set the priority of origin bio, cloned and splited bio
> auto inherit the priority of origin bio in clone process.
> 
> Co-developed-by: Yibin Ding <yibin.ding@xxxxxxxxxx>
> Signed-off-by: Yibin Ding <yibin.ding@xxxxxxxxxx>
> Signed-off-by: Hongyu Jin <hongyu.jin@xxxxxxxxxx>

This patch's subject needs fixing (this is a fix, not an optimization)
and the header needs fixing (various issues that make it hard to
read).

This should also be tagged with:
Fixes: a78418e6a04c9 ("block: Always initialize bio IO priority on submit")

(commit 82b74cac28493 was commit immediately prior that placed the
direct call incorrectly)

Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>

> ---
>  block/blk-core.c | 10 ++++++++++
>  block/blk-mq.c   | 11 -----------
>  2 files changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index fdf25b8d6e78..68158c327aea 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -49,6 +49,7 @@
>  #include "blk-pm.h"
>  #include "blk-cgroup.h"
>  #include "blk-throttle.h"
> +#include "blk-ioprio.h"
>  
>  struct dentry *blk_debugfs_root;
>  
> @@ -809,6 +810,14 @@ void submit_bio_noacct(struct bio *bio)
>  }
>  EXPORT_SYMBOL(submit_bio_noacct);
>  
> +static void bio_set_ioprio(struct bio *bio)
> +{
> +	/* Nobody set ioprio so far? Initialize it based on task's nice value */
> +	if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE)
> +		bio->bi_ioprio = get_current_ioprio();
> +	blkcg_set_ioprio(bio);
> +}
> +
>  /**
>   * submit_bio - submit a bio to the block device layer for I/O
>   * @bio: The &struct bio which describes the I/O
> @@ -831,6 +840,7 @@ void submit_bio(struct bio *bio)
>  		count_vm_events(PGPGOUT, bio_sectors(bio));
>  	}
>  
> +	bio_set_ioprio(bio);
>  	submit_bio_noacct(bio);
>  }
>  EXPORT_SYMBOL(submit_bio);
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index e2d11183f62e..a6e2609df9c9 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -40,7 +40,6 @@
>  #include "blk-stat.h"
>  #include "blk-mq-sched.h"
>  #include "blk-rq-qos.h"
> -#include "blk-ioprio.h"
>  
>  static DEFINE_PER_CPU(struct llist_head, blk_cpu_done);
>  static DEFINE_PER_CPU(call_single_data_t, blk_cpu_csd);
> @@ -2922,14 +2921,6 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
>  	return rq;
>  }
>  
> -static void bio_set_ioprio(struct bio *bio)
> -{
> -	/* Nobody set ioprio so far? Initialize it based on task's nice value */
> -	if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE)
> -		bio->bi_ioprio = get_current_ioprio();
> -	blkcg_set_ioprio(bio);
> -}
> -
>  /**
>   * blk_mq_submit_bio - Create and send a request to block device.
>   * @bio: Bio pointer.
> @@ -2963,8 +2954,6 @@ void blk_mq_submit_bio(struct bio *bio)
>  	if (!bio_integrity_prep(bio))
>  		return;
>  
> -	bio_set_ioprio(bio);
> -
>  	rq = blk_mq_get_cached_request(q, plug, &bio, nr_segs);
>  	if (!rq) {
>  		if (!bio)
> -- 
> 2.34.1
> 
>