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| author |   Tejun Heo <tj@kernel.org> | 2019-06-27 13:39:52 -0700 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2019-07-10 09:00:57 -0600 |
| commit | d3f77dfdc71835f8db71ca57d272b1fbec9dfc18 (patch) | |
| tree | ced59cee416b39c3c2f80c647c736a2d378772e3 /include/linux/blk-cgroup.h | |
| parent | blkcg, writeback: Implement wbc_blkcg_css() (diff) | |
| download | wireguard-linux-d3f77dfdc71835f8db71ca57d272b1fbec9dfc18.tar.xz wireguard-linux-d3f77dfdc71835f8db71ca57d272b1fbec9dfc18.zip | |
blkcg: implement REQ_CGROUP_PUNT
When a shared kthread needs to issue a bio for a cgroup, doing so
synchronously can lead to priority inversions as the kthread can be
trapped waiting for that cgroup. This patch implements
REQ_CGROUP_PUNT flag which makes submit_bio() punt the actual issuing
to a dedicated per-blkcg work item to avoid such priority inversions.
This will be used to fix priority inversions in btrfs compression and
should be generally useful as we grow filesystem support for
comprehensive IO control.
Cc: Chris Mason <clm@fb.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blk-cgroup.h')
| -rw-r--r-- | include/linux/blk-cgroup.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 33f23a858438..689a58231288 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -132,13 +132,17 @@ struct blkcg_gq { struct blkg_policy_data *pd[BLKCG_MAX_POLS]; - struct rcu_head rcu_head; + spinlock_t async_bio_lock; + struct bio_list async_bios; + struct work_struct async_bio_work; atomic_t use_delay; atomic64_t delay_nsec; atomic64_t delay_start; u64 last_delay; int last_use; + + struct rcu_head rcu_head; }; typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp); @@ -701,6 +705,15 @@ static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg struct bio *bio) { return false; } #endif +bool __blkcg_punt_bio_submit(struct bio *bio); + +static inline bool blkcg_punt_bio_submit(struct bio *bio) +{ + if (bio->bi_opf & REQ_CGROUP_PUNT) + return __blkcg_punt_bio_submit(bio); + else + return false; +} static inline void blkcg_bio_issue_init(struct bio *bio) { @@ -848,6 +861,7 @@ static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; } static inline void blkg_get(struct blkcg_gq *blkg) { } static inline void blkg_put(struct blkcg_gq *blkg) { } +static inline bool blkcg_punt_bio_submit(struct bio *bio) { return false; } static inline void blkcg_bio_issue_init(struct bio *bio) { } static inline bool blkcg_bio_issue_check(struct request_queue *q, struct bio *bio) { return true; } |