Btrfs: delayed-inode: use rb_first_cached for ins_root and del_root

rb_first_cached() trades an extra pointer "leftmost" for doing the same job as
rb_first() but in O(1).

Functions manipulating delayed_item need to get the first entry, this converts
it to use rb_first_cached().

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 47ce74c..15dcbd6 100644 (file)
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -42,8 +42,8 @@ static inline void btrfs_init_delayed_node(
        delayed_node->root = root;
        delayed_node->inode_id = inode_id;
        refcount_set(&delayed_node->refs, 0);
-       delayed_node->ins_root = RB_ROOT;
-       delayed_node->del_root = RB_ROOT;
+       delayed_node->ins_root = RB_ROOT_CACHED;
+       delayed_node->del_root = RB_ROOT_CACHED;
        mutex_init(&delayed_node->mutex);
        INIT_LIST_HEAD(&delayed_node->n_list);
        INIT_LIST_HEAD(&delayed_node->p_list);
@@ -390,7 +390,7 @@ static struct btrfs_delayed_item *__btrfs_lookup_delayed_insertion_item(
                                        struct btrfs_delayed_node *delayed_node,
                                        struct btrfs_key *key)
 {
-       return __btrfs_lookup_delayed_item(&delayed_node->ins_root, key,
+       return __btrfs_lookup_delayed_item(&delayed_node->ins_root.rb_root, key,
                                           NULL, NULL);
 }
 
@@ -400,9 +400,10 @@ static int __btrfs_add_delayed_item(struct btrfs_delayed_node *delayed_node,
 {
        struct rb_node **p, *node;
        struct rb_node *parent_node = NULL;
-       struct rb_root *root;
+       struct rb_root_cached *root;
        struct btrfs_delayed_item *item;
        int cmp;
+       bool leftmost = true;
 
        if (action == BTRFS_DELAYED_INSERTION_ITEM)
                root = &delayed_node->ins_root;
@@ -410,7 +411,7 @@ static int __btrfs_add_delayed_item(struct btrfs_delayed_node *delayed_node,
                root = &delayed_node->del_root;
        else
                BUG();
-       p = &root->rb_node;
+       p = &root->rb_root.rb_node;
        node = &ins->rb_node;
 
        while (*p) {
@@ -419,16 +420,18 @@ static int __btrfs_add_delayed_item(struct btrfs_delayed_node *delayed_node,
                                 rb_node);
 
                cmp = btrfs_comp_cpu_keys(&item->key, &ins->key);
-               if (cmp < 0)
+               if (cmp < 0) {
                        p = &(*p)->rb_right;
-               else if (cmp > 0)
+                       leftmost = false;
+               } else if (cmp > 0) {
                        p = &(*p)->rb_left;
-               else
+               } else {
                        return -EEXIST;
+               }
        }
 
        rb_link_node(node, parent_node, p);
-       rb_insert_color(node, root);
+       rb_insert_color_cached(node, root, leftmost);
        ins->delayed_node = delayed_node;
        ins->ins_or_del = action;
 
@@ -468,7 +471,7 @@ static void finish_one_item(struct btrfs_delayed_root *delayed_root)
 
 static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
 {
-       struct rb_root *root;
+       struct rb_root_cached *root;
        struct btrfs_delayed_root *delayed_root;
 
        delayed_root = delayed_item->delayed_node->root->fs_info->delayed_root;
@@ -482,7 +485,7 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
        else
                root = &delayed_item->delayed_node->del_root;
 
-       rb_erase(&delayed_item->rb_node, root);
+       rb_erase_cached(&delayed_item->rb_node, root);
        delayed_item->delayed_node->count--;
 
        finish_one_item(delayed_root);
@@ -503,7 +506,7 @@ static struct btrfs_delayed_item *__btrfs_first_delayed_insertion_item(
        struct rb_node *p;
        struct btrfs_delayed_item *item = NULL;
 
-       p = rb_first(&delayed_node->ins_root);
+       p = rb_first_cached(&delayed_node->ins_root);
        if (p)
                item = rb_entry(p, struct btrfs_delayed_item, rb_node);
 
@@ -516,7 +519,7 @@ static struct btrfs_delayed_item *__btrfs_first_delayed_deletion_item(
        struct rb_node *p;
        struct btrfs_delayed_item *item = NULL;
 
-       p = rb_first(&delayed_node->del_root);
+       p = rb_first_cached(&delayed_node->del_root);
        if (p)
                item = rb_entry(p, struct btrfs_delayed_item, rb_node);
 

diff --git a/fs/btrfs/delayed-inode.h b/fs/btrfs/delayed-inode.h
index 33536cd..74ae226 100644 (file)
--- a/fs/btrfs/delayed-inode.h
+++ b/fs/btrfs/delayed-inode.h
@@ -50,8 +50,8 @@ struct btrfs_delayed_node {
         * is waiting to be dealt with by the async worker.
         */
        struct list_head p_list;
-       struct rb_root ins_root;
-       struct rb_root del_root;
+       struct rb_root_cached ins_root;
+       struct rb_root_cached del_root;
        struct mutex mutex;
        struct btrfs_inode_item inode_item;
        refcount_t refs;