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 <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
parent
07b05bcc32
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a7b39b4e96
38
block/bio.c
38
block/bio.c
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@ -2028,6 +2028,41 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
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return 0;
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}
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/**
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* bio_associate_create_blkg - associate a bio with a blkg from q
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* @q: request_queue where bio is going
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* @bio: target bio
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*
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* Associate @bio with the blkg found from the bio's css and the request_queue.
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* If one is not found, bio_lookup_blkg creates the blkg.
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*/
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int bio_associate_create_blkg(struct request_queue *q, struct bio *bio)
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{
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struct blkcg *blkcg;
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struct blkcg_gq *blkg;
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int ret = 0;
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/* someone has already associated this bio with a blkg */
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if (bio->bi_blkg)
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return ret;
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rcu_read_lock();
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bio_associate_blkcg(bio, NULL);
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blkcg = bio_blkcg(bio);
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if (!blkcg->css.parent) {
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ret = bio_associate_blkg(bio, q->root_blkg);
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} else {
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blkg = blkg_lookup_create(blkcg, q);
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ret = bio_associate_blkg(bio, blkg);
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}
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rcu_read_unlock();
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return ret;
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}
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/**
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* bio_disassociate_task - undo bio_associate_current()
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* @bio: target bio
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@ -2057,6 +2092,9 @@ void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
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{
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if (src->bi_css)
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WARN_ON(bio_associate_blkcg(dst, src->bi_css));
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if (src->bi_blkg)
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bio_associate_blkg(dst, src->bi_blkg);
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}
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EXPORT_SYMBOL_GPL(bio_clone_blkcg_association);
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#endif /* CONFIG_BLK_CGROUP */
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@ -392,34 +392,14 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio,
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spinlock_t *lock)
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{
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struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos);
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struct blkcg *blkcg;
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struct blkcg_gq *blkg;
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struct request_queue *q = rqos->q;
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struct blkcg_gq *blkg = bio->bi_blkg;
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bool issue_as_root = bio_issue_as_root_blkg(bio);
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if (!blk_iolatency_enabled(blkiolat))
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return;
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rcu_read_lock();
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bio_associate_blkcg(bio, NULL);
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blkcg = bio_blkcg(bio);
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blkg = blkg_lookup(blkcg, q);
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if (unlikely(!blkg)) {
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if (!lock)
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spin_lock_irq(q->queue_lock);
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blkg = __blkg_lookup_create(blkcg, q);
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if (IS_ERR(blkg))
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blkg = NULL;
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if (!lock)
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spin_unlock_irq(q->queue_lock);
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}
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if (!blkg)
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goto out;
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bio_issue_init(&bio->bi_issue, bio_sectors(bio));
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bio_associate_blkg(bio, blkg);
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out:
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rcu_read_unlock();
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while (blkg && blkg->parent) {
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struct iolatency_grp *iolat = blkg_to_lat(blkg);
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if (!iolat) {
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@ -2118,9 +2118,6 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td)
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static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)
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{
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#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
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/* fallback to root_blkg if we fail to get a blkg ref */
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if (bio->bi_css && (bio_associate_blkg(bio, tg_to_blkg(tg)) == -ENODEV))
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bio_associate_blkg(bio, bio->bi_disk->queue->root_blkg);
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bio_issue_init(&bio->bi_issue, bio_sectors(bio));
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#endif
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}
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@ -2129,7 +2126,7 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
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struct bio *bio)
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{
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struct throtl_qnode *qn = NULL;
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struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg);
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struct throtl_grp *tg = blkg_to_tg(blkg);
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struct throtl_service_queue *sq;
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bool rw = bio_data_dir(bio);
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bool throttled = false;
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@ -542,11 +542,14 @@ static inline int bio_associate_blkcg_from_page(struct bio *bio,
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#ifdef CONFIG_BLK_CGROUP
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int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
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int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg);
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int bio_associate_create_blkg(struct request_queue *q, struct bio *bio);
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void bio_disassociate_task(struct bio *bio);
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void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
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#else /* CONFIG_BLK_CGROUP */
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static inline int bio_associate_blkcg(struct bio *bio,
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struct cgroup_subsys_state *blkcg_css) { return 0; }
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static inline int bio_associate_create_blkg(struct request_queue *q,
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struct bio *bio) { return 0; }
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static inline void bio_disassociate_task(struct bio *bio) { }
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static inline void bio_clone_blkcg_association(struct bio *dst,
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struct bio *src) { }
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@ -900,29 +900,17 @@ static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg
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static inline bool blkcg_bio_issue_check(struct request_queue *q,
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struct bio *bio)
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{
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struct blkcg *blkcg;
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struct blkcg_gq *blkg;
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bool throtl = false;
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rcu_read_lock();
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/* associate blkcg if bio hasn't attached one */
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bio_associate_blkcg(bio, NULL);
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blkcg = bio_blkcg(bio);
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blkg = blkg_lookup(blkcg, q);
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if (unlikely(!blkg)) {
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spin_lock_irq(q->queue_lock);
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blkg = __blkg_lookup_create(blkcg, q);
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if (IS_ERR(blkg))
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blkg = NULL;
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spin_unlock_irq(q->queue_lock);
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}
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bio_associate_create_blkg(q, bio);
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blkg = bio->bi_blkg;
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throtl = blk_throtl_bio(q, blkg, bio);
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if (!throtl) {
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blkg = blkg ?: q->root_blkg;
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/*
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* If the bio is flagged with BIO_QUEUE_ENTERED it means this
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* is a split bio and we would have already accounted for the
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