diff options
author | Christoph Hellwig <hch@lst.de> | 2020-06-27 09:31:54 +0200 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2020-06-29 09:09:08 -0600 |
commit | 13c7863d48c160152c42c62700a722293bddeca4 (patch) | |
tree | 280a881afe71a1dad7e0d0897b4b3b8ef59ea4da /block | |
parent | a5b97526bf2860fe8306959f19ee428d1f5cc732 (diff) | |
download | lwn-13c7863d48c160152c42c62700a722293bddeca4.tar.gz lwn-13c7863d48c160152c42c62700a722293bddeca4.zip |
block: move the initial blkg lookup into blkg_tryget_closest
By moving the initial blkg lookup into blkg_tryget_closest we get
a nicely self contained routines that does all the RCU locking.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r-- | block/blk-cgroup.c | 33 |
1 files changed, 14 insertions, 19 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 0912820d4f81..d21ec2acd716 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1716,19 +1716,20 @@ void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) /** * blkg_tryget_closest - try and get a blkg ref on the closet blkg - * @blkg: blkg to get + * @bio: target bio + * @css: target css * - * This needs to be called rcu protected. As the failure mode here is to walk - * up the blkg tree, this ensure that the blkg->parent pointers are always - * valid. This returns the blkg that it ended up taking a reference on or %NULL - * if no reference was taken. + * As the failure mode here is to walk up the blkg tree, this ensure that the + * blkg->parent pointers are always valid. This returns the blkg that it ended + * up taking a reference on or %NULL if no reference was taken. */ -static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg) +static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio, + struct cgroup_subsys_state *css) { - struct blkcg_gq *ret_blkg = NULL; - - WARN_ON_ONCE(!rcu_read_lock_held()); + struct blkcg_gq *blkg, *ret_blkg = NULL; + rcu_read_lock(); + blkg = blkg_lookup_create(css_to_blkcg(css), bio->bi_disk->queue); while (blkg) { if (blkg_tryget(blkg)) { ret_blkg = blkg; @@ -1736,6 +1737,7 @@ static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg) } blkg = blkg->parent; } + rcu_read_unlock(); return ret_blkg; } @@ -1757,21 +1759,14 @@ static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg) void bio_associate_blkg_from_css(struct bio *bio, struct cgroup_subsys_state *css) { - struct request_queue *q = bio->bi_disk->queue; - if (bio->bi_blkg) blkg_put(bio->bi_blkg); if (css && css->parent) { - struct blkcg_gq *blkg; - - rcu_read_lock(); - blkg = blkg_lookup_create(css_to_blkcg(css), q); - bio->bi_blkg = blkg_tryget_closest(blkg); - rcu_read_unlock(); + bio->bi_blkg = blkg_tryget_closest(bio, css); } else { - blkg_get(q->root_blkg); - bio->bi_blkg = q->root_blkg; + blkg_get(bio->bi_disk->queue->root_blkg); + bio->bi_blkg = bio->bi_disk->queue->root_blkg; } } EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css); |