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author | Fam Zheng <zhengfeiran@bytedance.com> | 2019-08-28 06:54:52 +0300 |
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committer | Jens Axboe <axboe@kernel.dk> | 2019-09-06 23:33:50 +0300 |
commit | 5ff047e32812f57c13389c4a9cdb1427620b3a6f (patch) | |
tree | f685166995006477cb0eaef5296ff990ad7d3b1f /block/bfq-cgroup.c | |
parent | e9d3c866bf4cdbb6637e6cb268c26dfdf06d8cd3 (diff) | |
download | linux-5ff047e32812f57c13389c4a9cdb1427620b3a6f.tar.xz |
bfq: Extract bfq_group_set_weight from bfq_io_set_weight_legacy
This function will be useful when we update weight from the soon-coming
per-device interface.
Signed-off-by: Fam Zheng <zhengfeiran@bytedance.com>
Reviewed-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bfq-cgroup.c')
-rw-r--r-- | block/bfq-cgroup.c | 60 |
1 files changed, 32 insertions, 28 deletions
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index e6fb537b4bfc..102bdfd6f72c 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -919,6 +919,36 @@ static int bfq_io_show_weight(struct seq_file *sf, void *v) return 0; } +static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight) +{ + /* + * Setting the prio_changed flag of the entity + * to 1 with new_weight == weight would re-set + * the value of the weight to its ioprio mapping. + * Set the flag only if necessary. + */ + if ((unsigned short)weight != bfqg->entity.new_weight) { + bfqg->entity.new_weight = (unsigned short)weight; + /* + * Make sure that the above new value has been + * stored in bfqg->entity.new_weight before + * setting the prio_changed flag. In fact, + * this flag may be read asynchronously (in + * critical sections protected by a different + * lock than that held here), and finding this + * flag set may cause the execution of the code + * for updating parameters whose value may + * depend also on bfqg->entity.new_weight (in + * __bfq_entity_update_weight_prio). + * This barrier makes sure that the new value + * of bfqg->entity.new_weight is correctly + * seen in that code. + */ + smp_wmb(); + bfqg->entity.prio_changed = 1; + } +} + static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, struct cftype *cftype, u64 val) @@ -937,34 +967,8 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { struct bfq_group *bfqg = blkg_to_bfqg(blkg); - if (!bfqg) - continue; - /* - * Setting the prio_changed flag of the entity - * to 1 with new_weight == weight would re-set - * the value of the weight to its ioprio mapping. - * Set the flag only if necessary. - */ - if ((unsigned short)val != bfqg->entity.new_weight) { - bfqg->entity.new_weight = (unsigned short)val; - /* - * Make sure that the above new value has been - * stored in bfqg->entity.new_weight before - * setting the prio_changed flag. In fact, - * this flag may be read asynchronously (in - * critical sections protected by a different - * lock than that held here), and finding this - * flag set may cause the execution of the code - * for updating parameters whose value may - * depend also on bfqg->entity.new_weight (in - * __bfq_entity_update_weight_prio). - * This barrier makes sure that the new value - * of bfqg->entity.new_weight is correctly - * seen in that code. - */ - smp_wmb(); - bfqg->entity.prio_changed = 1; - } + if (bfqg) + bfq_group_set_weight(bfqg, val); } spin_unlock_irq(&blkcg->lock); |