diff options
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 98569c2f373ec..e3c591dd8f19d 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -632,6 +632,13 @@ static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) return pblkg ? blkg_to_cfqg(pblkg) : NULL; } +static inline bool cfqg_is_descendant(struct cfq_group *cfqg, + struct cfq_group *ancestor) +{ + return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup, + cfqg_to_blkg(ancestor)->blkcg->css.cgroup); +} + static inline void cfqg_get(struct cfq_group *cfqg) { return blkg_get(cfqg_to_blkg(cfqg)); @@ -758,6 +765,11 @@ static void cfqg_stats_xfer_dead(struct cfq_group *cfqg) #else /* CONFIG_CFQ_GROUP_IOSCHED */ static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; } +static inline bool cfqg_is_descendant(struct cfq_group *cfqg, + struct cfq_group *ancestor) +{ + return true; +} static inline void cfqg_get(struct cfq_group *cfqg) { } static inline void cfqg_put(struct cfq_group *cfqg) { } @@ -3953,7 +3965,12 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) return true; - if (new_cfqq->cfqg != cfqq->cfqg) + /* + * Treat ancestors of current cgroup the same way as current cgroup. + * For anybody else we disallow preemption to guarantee service + * fairness among cgroups. + */ + if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg)) return false; if (cfq_slice_used(cfqq)) |