As rbtree has native support of caching leftmost node, i.e. rb_root_cached, no need to do the caching by ourselves.
Signed-off-by: Liu Bo <[email protected]> --- block/blk-throttle.c | 41 +++++++++++++++-------------------------- 1 file changed, 15 insertions(+), 26 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index a3eede00d302..b1f7623b666b 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -84,8 +84,7 @@ struct throtl_service_queue { * RB tree of active children throtl_grp's, which are sorted by * their ->disptime. */ - struct rb_root pending_tree; /* RB tree of active tgs */ - struct rb_node *first_pending; /* first node in the tree */ + struct rb_root_cached pending_tree; /* RB tree of active tgs */ unsigned int nr_pending; /* # queued in the tree */ unsigned long first_pending_disptime; /* disptime of the first tg */ struct timer_list pending_timer; /* fires on first_pending_disptime */ @@ -475,7 +474,7 @@ static void throtl_service_queue_init(struct throtl_service_queue *sq) { INIT_LIST_HEAD(&sq->queued[0]); INIT_LIST_HEAD(&sq->queued[1]); - sq->pending_tree = RB_ROOT; + sq->pending_tree = RB_ROOT_CACHED; timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0); } @@ -616,31 +615,23 @@ static void throtl_pd_free(struct blkg_policy_data *pd) static struct throtl_grp * throtl_rb_first(struct throtl_service_queue *parent_sq) { + struct rb_node *n; /* Service tree is empty */ if (!parent_sq->nr_pending) return NULL; - if (!parent_sq->first_pending) - parent_sq->first_pending = rb_first(&parent_sq->pending_tree); - - if (parent_sq->first_pending) - return rb_entry_tg(parent_sq->first_pending); - - return NULL; -} - -static void rb_erase_init(struct rb_node *n, struct rb_root *root) -{ - rb_erase(n, root); - RB_CLEAR_NODE(n); + n = rb_first_cached(&parent_sq->pending_tree); + WARN_ON_ONCE(!n); + if (!n) + return NULL; + return rb_entry_tg(n); } static void throtl_rb_erase(struct rb_node *n, struct throtl_service_queue *parent_sq) { - if (parent_sq->first_pending == n) - parent_sq->first_pending = NULL; - rb_erase_init(n, &parent_sq->pending_tree); + rb_erase_cached(n, &parent_sq->pending_tree); + RB_CLEAR_NODE(n); --parent_sq->nr_pending; } @@ -658,11 +649,11 @@ static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) static void tg_service_queue_add(struct throtl_grp *tg) { struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; - struct rb_node **node = &parent_sq->pending_tree.rb_node; + struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node; struct rb_node *parent = NULL; struct throtl_grp *__tg; unsigned long key = tg->disptime; - int left = 1; + bool leftmost = true; while (*node != NULL) { parent = *node; @@ -672,15 +663,13 @@ static void tg_service_queue_add(struct throtl_grp *tg) node = &parent->rb_left; else { node = &parent->rb_right; - left = 0; + leftmost = false; } } - if (left) - parent_sq->first_pending = &tg->rb_node; - rb_link_node(&tg->rb_node, parent, node); - rb_insert_color(&tg->rb_node, &parent_sq->pending_tree); + rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree, + leftmost); } static void __throtl_enqueue_tg(struct throtl_grp *tg) -- 1.8.3.1
