From a7b39b4e961c4e2b3ed837803a7441a65c90ce33 Mon Sep 17 00:00:00 2001 From: "Dennis Zhou (Facebook)" Date: Tue, 11 Sep 2018 14:41:29 -0400 Subject: blkcg: always associate a bio with a blkg Previously, blkg's were only assigned as needed by blk-iolatency and blk-throttle. bio->css was also always being associated while blkg was being looked up and then thrown away in blkcg_bio_issue_check. This patch begins the cleanup of bio->css and bio->bi_blkg by always associating a blkg in blkcg_bio_issue_check. This tries to create the blkg, but if it is not possible, falls back to using the root_blkg of the request_queue. Therefore, a bio will always be associated with a blkg. The duplicate association logic is removed from blk-throttle and blk-iolatency. Signed-off-by: Dennis Zhou Acked-by: Tejun Heo Signed-off-by: Jens Axboe --- block/bio.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) (limited to 'block/bio.c') diff --git a/block/bio.c b/block/bio.c index bfd41e8b53a8..748d7132f172 100644 --- a/block/bio.c +++ b/block/bio.c @@ -2028,6 +2028,41 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg) return 0; } +/** + * bio_associate_create_blkg - associate a bio with a blkg from q + * @q: request_queue where bio is going + * @bio: target bio + * + * Associate @bio with the blkg found from the bio's css and the request_queue. + * If one is not found, bio_lookup_blkg creates the blkg. + */ +int bio_associate_create_blkg(struct request_queue *q, struct bio *bio) +{ + struct blkcg *blkcg; + struct blkcg_gq *blkg; + int ret = 0; + + /* someone has already associated this bio with a blkg */ + if (bio->bi_blkg) + return ret; + + rcu_read_lock(); + + bio_associate_blkcg(bio, NULL); + blkcg = bio_blkcg(bio); + + if (!blkcg->css.parent) { + ret = bio_associate_blkg(bio, q->root_blkg); + } else { + blkg = blkg_lookup_create(blkcg, q); + + ret = bio_associate_blkg(bio, blkg); + } + + rcu_read_unlock(); + return ret; +} + /** * bio_disassociate_task - undo bio_associate_current() * @bio: target bio @@ -2057,6 +2092,9 @@ void bio_clone_blkcg_association(struct bio *dst, struct bio *src) { if (src->bi_css) WARN_ON(bio_associate_blkcg(dst, src->bi_css)); + + if (src->bi_blkg) + bio_associate_blkg(dst, src->bi_blkg); } EXPORT_SYMBOL_GPL(bio_clone_blkcg_association); #endif /* CONFIG_BLK_CGROUP */ -- cgit v1.2.3