diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/blk-cgroup.h | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index dd5841a42c33..58abde49f8c5 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -14,6 +14,8 @@ * Nauman Rafique <nauman@google.com> */ +#include <linux/atomic.h> +#include <linux/compiler.h> #include <linux/types.h> struct bio; @@ -24,10 +26,29 @@ struct gendisk; #ifdef CONFIG_BLK_CGROUP extern struct cgroup_subsys_state * const blkcg_root_css; +extern atomic_t blkcg_nr_congested; void blkcg_schedule_throttle(struct gendisk *disk, bool use_memdelay); void blkcg_maybe_throttle_current(void); -bool blk_cgroup_congested(void); +bool __blk_cgroup_congested(void); + +/** + * blk_cgroup_congested - is the current task in a throttled blkcg? + * + * Called from mm hot paths where the answer is almost always false, so keep + * that case to a load and a branch and only walk the hierarchy out of line + * when something in the system really is throttled. + * + * Return: %true if the current task's blkcg or any of its ancestors is + * throttled, %false otherwise. + */ +static inline bool blk_cgroup_congested(void) +{ + if (likely(!atomic_read(&blkcg_nr_congested))) + return false; + return __blk_cgroup_congested(); +} + void blkcg_pin_online(struct cgroup_subsys_state *blkcg_css); void blkcg_unpin_online(struct cgroup_subsys_state *blkcg_css); struct list_head *blkcg_get_cgwb_list(struct cgroup_subsys_state *css); |