From: Paolo Valente paolo.valente@linaro.org
commit 576682fa52cbd95deb3773449566274f206acc58 upstream.
bfq_reparent_leaf_entity() reparents the input leaf entity (a leaf entity represents just a bfq_queue in an entity tree). Yet, the input entity is guaranteed to always be a leaf entity only in two-level entity trees. In this respect, because of the error fixed by commit 14afc5936197 ("block, bfq: fix overwrite of bfq_group pointer in bfq_find_set_group()"), all (wrongly collapsed) entity trees happened to actually have only two levels. After the latter commit, this does not hold any longer.
This commit fixes this problem by modifying bfq_reparent_leaf_entity(), so that it searches an active leaf entity down the path that stems from the input entity. Such a leaf entity is guaranteed to exist when bfq_reparent_leaf_entity() is invoked.
Tested-by: cki-project@redhat.com Signed-off-by: Paolo Valente paolo.valente@linaro.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/bfq-cgroup.c | 48 +++++++++++++++++++++++++++++++----------------- 1 file changed, 31 insertions(+), 17 deletions(-)
--- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -798,39 +798,53 @@ static void bfq_flush_idle_tree(struct b /** * bfq_reparent_leaf_entity - move leaf entity to the root_group. * @bfqd: the device data structure with the root group. - * @entity: the entity to move. + * @entity: the entity to move, if entity is a leaf; or the parent entity + * of an active leaf entity to move, if entity is not a leaf. */ static void bfq_reparent_leaf_entity(struct bfq_data *bfqd, - struct bfq_entity *entity) + struct bfq_entity *entity, + int ioprio_class) { - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + struct bfq_queue *bfqq; + struct bfq_entity *child_entity = entity;
+ while (child_entity->my_sched_data) { /* leaf not reached yet */ + struct bfq_sched_data *child_sd = child_entity->my_sched_data; + struct bfq_service_tree *child_st = child_sd->service_tree + + ioprio_class; + struct rb_root *child_active = &child_st->active; + + child_entity = bfq_entity_of(rb_first(child_active)); + + if (!child_entity) + child_entity = child_sd->in_service_entity; + } + + bfqq = bfq_entity_to_bfqq(child_entity); bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); }
/** - * bfq_reparent_active_entities - move to the root group all active - * entities. + * bfq_reparent_active_queues - move to the root group all active queues. * @bfqd: the device data structure with the root group. * @bfqg: the group to move from. - * @st: the service tree with the entities. + * @st: the service tree to start the search from. */ -static void bfq_reparent_active_entities(struct bfq_data *bfqd, - struct bfq_group *bfqg, - struct bfq_service_tree *st) +static void bfq_reparent_active_queues(struct bfq_data *bfqd, + struct bfq_group *bfqg, + struct bfq_service_tree *st, + int ioprio_class) { struct rb_root *active = &st->active; - struct bfq_entity *entity = NULL; - - if (!RB_EMPTY_ROOT(&st->active)) - entity = bfq_entity_of(rb_first(active)); + struct bfq_entity *entity;
- for (; entity ; entity = bfq_entity_of(rb_first(active))) - bfq_reparent_leaf_entity(bfqd, entity); + while ((entity = bfq_entity_of(rb_first(active)))) + bfq_reparent_leaf_entity(bfqd, entity, ioprio_class);
if (bfqg->sched_data.in_service_entity) bfq_reparent_leaf_entity(bfqd, - bfqg->sched_data.in_service_entity); + bfqg->sched_data.in_service_entity, + ioprio_class); }
/** @@ -881,7 +895,7 @@ static void bfq_pd_offline(struct blkg_p * There is no need to put the sync queues, as the * scheduler has taken no reference. */ - bfq_reparent_active_entities(bfqd, bfqg, st); + bfq_reparent_active_queues(bfqd, bfqg, st, i); }
__bfq_deactivate_entity(entity, false);