On Sun, Sep 13, 2026 at 02:54:39PM +0800, Yu Kuai wrote:
> @@ -6243,10 +6245,17 @@ static void bfq_insert_request(struct blk_mq_hw_ctx
> *hctx, struct request *rq,
> bool idle_timer_disabled = false;
> blk_opf_t cmd_flags;
> LIST_HEAD(free);
>
> #ifdef CONFIG_BFQ_GROUP_IOSCHED
> + /*
> + * Pin the blkg used to look up bfqg. If this is the first IO for
> + * the blkcg on this queue, create the bfqg before holding bfqd->lock.
> + */
> + if (rq->bio && !bio_flagged(rq->bio, BIO_BLKG_REF))
> + bio_blkg(rq->bio);
Can rq->bio be NULL here? flush or empty passthrough request should
never enter the scheuler.
> if (!cgroup_subsys_on_dfl(io_cgrp_subsys) && rq->bio)
> bfqg_stats_update_legacy_io(q, rq);
But I guess given that the code below checks it, we should at least
be consistent, so I guess it is better to keep it for now.
>
> static inline void dm_bio_record(struct dm_bio_details *bd, struct bio *bio)
> {
> bd->bi_bdev = bio->bi_bdev;
> - bd->bi_flags = bio->bi_flags;
> + /* Restoring an ownership bit cannot recreate the associated reference.
> */
> + bd->bi_flags = bio->bi_flags & ~(1U << BIO_BLKG_REF);
I have a bit of a hard time parsing this, the line also is overly
long.
