block/cfq: replace cfq_rb_root leftmost caching

... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.19029-11-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9b86e9b352e9f806b57e84e7b4875705a03356ed..9ba5345ebc9a7c13a59b12ce1a0003b54c2df253 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -93,13 +93,12 @@ struct cfq_ttime {
  * move this into the elevator for the rq sorting as well.
  */
 struct cfq_rb_root {
-       struct rb_root rb;
-       struct rb_node *left;
+       struct rb_root_cached rb;
        unsigned count;
        u64 min_vdisktime;
        struct cfq_ttime ttime;
 };
-#define CFQ_RB_ROOT    (struct cfq_rb_root) { .rb = RB_ROOT, \
+#define CFQ_RB_ROOT    (struct cfq_rb_root) { .rb = RB_ROOT_CACHED, \
                        .ttime = {.last_end_request = ktime_get_ns(),},}
 
 /*
@@ -981,10 +980,9 @@ static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
 
 static void update_min_vdisktime(struct cfq_rb_root *st)
 {
-       struct cfq_group *cfqg;
+       if (!RB_EMPTY_ROOT(&st->rb.rb_root)) {
+               struct cfq_group *cfqg = rb_entry_cfqg(st->rb.rb_leftmost);
 
-       if (st->left) {
-               cfqg = rb_entry_cfqg(st->left);
                st->min_vdisktime = max_vdisktime(st->min_vdisktime,
                                                  cfqg->vdisktime);
        }
@@ -1166,46 +1164,25 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2,
        }
 }
 
-/*
- * The below is leftmost cache rbtree addon
- */
 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
 {
        /* Service tree is empty */
        if (!root->count)
                return NULL;
 
-       if (!root->left)
-               root->left = rb_first(&root->rb);
-
-       if (root->left)
-               return rb_entry(root->left, struct cfq_queue, rb_node);
-
-       return NULL;
+       return rb_entry(rb_first_cached(&root->rb), struct cfq_queue, rb_node);
 }
 
 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
 {
-       if (!root->left)
-               root->left = rb_first(&root->rb);
-
-       if (root->left)
-               return rb_entry_cfqg(root->left);
-
-       return NULL;
+       return rb_entry_cfqg(rb_first_cached(&root->rb));
 }
 
-static void rb_erase_init(struct rb_node *n, struct rb_root *root)
+static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
 {
-       rb_erase(n, root);
+       rb_erase_cached(n, &root->rb);
        RB_CLEAR_NODE(n);
-}
 
-static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
-{
-       if (root->left == n)
-               root->left = NULL;
-       rb_erase_init(n, &root->rb);
        --root->count;
 }
 
@@ -1255,11 +1232,11 @@ cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
 static void
 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
 {
-       struct rb_node **node = &st->rb.rb_node;
+       struct rb_node **node = &st->rb.rb_root.rb_node;
        struct rb_node *parent = NULL;
        struct cfq_group *__cfqg;
        s64 key = cfqg_key(st, cfqg);
-       int left = 1;
+       bool leftmost = true;
 
        while (*node != NULL) {
                parent = *node;
@@ -1269,15 +1246,12 @@ __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
                        node = &parent->rb_left;
                else {
                        node = &parent->rb_right;
-                       left = 0;
+                       leftmost = false;
                }
        }
 
-       if (left)
-               st->left = &cfqg->rb_node;
-
        rb_link_node(&cfqg->rb_node, parent, node);
-       rb_insert_color(&cfqg->rb_node, &st->rb);
+       rb_insert_color_cached(&cfqg->rb_node, &st->rb, leftmost);
 }
 
 /*
@@ -1378,7 +1352,7 @@ cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
         * so that groups get lesser vtime based on their weights, so that
         * if group does not loose all if it was not continuously backlogged.
         */
-       n = rb_last(&st->rb);
+       n = rb_last(&st->rb.rb_root);
        if (n) {
                __cfqg = rb_entry_cfqg(n);
                cfqg->vdisktime = __cfqg->vdisktime +
@@ -2220,14 +2194,14 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        struct cfq_queue *__cfqq;
        u64 rb_key;
        struct cfq_rb_root *st;
-       int left;
+       bool leftmost = true;
        int new_cfqq = 1;
        u64 now = ktime_get_ns();
 
        st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
        if (cfq_class_idle(cfqq)) {
                rb_key = CFQ_IDLE_DELAY;
-               parent = rb_last(&st->rb);
+               parent = rb_last(&st->rb.rb_root);
                if (parent && parent != &cfqq->rb_node) {
                        __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
                        rb_key += __cfqq->rb_key;
@@ -2261,10 +2235,9 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                cfqq->service_tree = NULL;
        }
 
-       left = 1;
        parent = NULL;
        cfqq->service_tree = st;
-       p = &st->rb.rb_node;
+       p = &st->rb.rb_root.rb_node;
        while (*p) {
                parent = *p;
                __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
@@ -2276,16 +2249,13 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                        p = &parent->rb_left;
                else {
                        p = &parent->rb_right;
-                       left = 0;
+                       leftmost = false;
                }
        }
 
-       if (left)
-               st->left = &cfqq->rb_node;
-
        cfqq->rb_key = rb_key;
        rb_link_node(&cfqq->rb_node, parent, p);
-       rb_insert_color(&cfqq->rb_node, &st->rb);
+       rb_insert_color_cached(&cfqq->rb_node, &st->rb, leftmost);
        st->count++;
        if (add_front || !new_cfqq)
                return;
@@ -2732,7 +2702,7 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
        /* There is nothing to dispatch */
        if (!st)
                return NULL;
-       if (RB_EMPTY_ROOT(&st->rb))
+       if (RB_EMPTY_ROOT(&st->rb.rb_root))
                return NULL;
        return cfq_rb_first(st);
 }
@@ -3219,7 +3189,7 @@ static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
        struct cfq_rb_root *st = &cfqd->grp_service_tree;
        struct cfq_group *cfqg;
 
-       if (RB_EMPTY_ROOT(&st->rb))
+       if (RB_EMPTY_ROOT(&st->rb.rb_root))
                return NULL;
        cfqg = cfq_rb_first_group(st);
        update_min_vdisktime(st);