diff options
| -rw-r--r-- | include/linux/blk-cgroup.h | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 2951ea3541b1..d2f7f1b00fcf 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -586,28 +586,36 @@ static inline struct request_list *blk_get_rl(struct request_queue *q, rcu_read_lock(); - blkcg = bio_blkcg(bio); - if (!blkcg) - blkcg = css_to_blkcg(blkcg_css()); + if (bio && bio->bi_blkg) { + blkcg = bio->bi_blkg->blkcg; + if (blkcg == &blkcg_root) + goto rl_use_root; + + blkg_get(bio->bi_blkg); + rcu_read_unlock(); + return &bio->bi_blkg->rl; + } - /* bypass blkg lookup and use @q->root_rl directly for root */ + blkcg = css_to_blkcg(blkcg_css()); if (blkcg == &blkcg_root) - goto root_rl; + goto rl_use_root; - /* - * Try to use blkg->rl. blkg lookup may fail under memory pressure - * or if either the blkcg or queue is going away. Fall back to - * root_rl in such cases. - */ blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) - goto root_rl; + blkg = __blkg_lookup_create(blkcg, q); if (!blkg_try_get(blkg)) - goto root_rl; + goto rl_use_root; + rcu_read_unlock(); return &blkg->rl; -root_rl: + + /* + * Each blkg has its own request_list, however, the root blkcg + * uses the request_queue's root_rl. This is to avoid most + * overhead for the root blkcg. + */ +rl_use_root: rcu_read_unlock(); return &q->root_rl; } |