btrfs: update prelim_ref_insert() to use rb helpers

Update prelim_ref_insert() to use rb_find_add_cached().

There is a special change that the existing prelim_ref_compare() is
called with the first parameter as the existing ref in the rbtree.

But the newer rb_find_add_cached() expects the cmp() function to have
the first parameter as the to-be-added node, thus the new helper
prelim_ref_rb_add_cmp() need to adapt this new order.

Signed-off-by: Roger L. Beckermeyer III <beckerlee3@gmail.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 6d9f39c1d89c71dcf85bd053d8896ed286ac28b5..3d3923cfc35746c04f9aa2318b108de23718e891 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -250,6 +250,21 @@ static int prelim_ref_compare(const struct prelim_ref *ref1,
        return 0;
 }
 
+static int prelim_ref_rb_add_cmp(const struct rb_node *new,
+                                const struct rb_node *exist)
+{
+       const struct prelim_ref *ref_new =
+               rb_entry(new, struct prelim_ref, rbnode);
+       const struct prelim_ref *ref_exist =
+               rb_entry(exist, struct prelim_ref, rbnode);
+
+       /*
+        * prelim_ref_compare() expects the first parameter as the existing one,
+        * different from the rb_find_add_cached() order.
+        */
+       return prelim_ref_compare(ref_exist, ref_new);
+}
+
 static void update_share_count(struct share_check *sc, int oldcount,
                               int newcount, const struct prelim_ref *newref)
 {
@@ -278,55 +293,39 @@ static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
                              struct share_check *sc)
 {
        struct rb_root_cached *root;
-       struct rb_node **p;
-       struct rb_node *parent = NULL;
-       struct prelim_ref *ref;
-       int result;
-       bool leftmost = true;
+       struct rb_node *exist;
 
        root = &preftree->root;
-       p = &root->rb_root.rb_node;
-
-       while (*p) {
-               parent = *p;
-               ref = rb_entry(parent, struct prelim_ref, rbnode);
-               result = prelim_ref_compare(ref, newref);
-               if (result < 0) {
-                       p = &(*p)->rb_left;
-               } else if (result > 0) {
-                       p = &(*p)->rb_right;
-                       leftmost = false;
-               } else {
-                       /* Identical refs, merge them and free @newref */
-                       struct extent_inode_elem *eie = ref->inode_list;
+       exist = rb_find_add_cached(&newref->rbnode, root, prelim_ref_rb_add_cmp);
+       if (exist) {
+               struct prelim_ref *ref = rb_entry(exist, struct prelim_ref, rbnode);
+               /* Identical refs, merge them and free @newref */
+               struct extent_inode_elem *eie = ref->inode_list;
 
-                       while (eie && eie->next)
-                               eie = eie->next;
+               while (eie && eie->next)
+                       eie = eie->next;
 
-                       if (!eie)
-                               ref->inode_list = newref->inode_list;
-                       else
-                               eie->next = newref->inode_list;
-                       trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
-                                                    preftree->count);
-                       /*
-                        * A delayed ref can have newref->count < 0.
-                        * The ref->count is updated to follow any
-                        * BTRFS_[ADD|DROP]_DELAYED_REF actions.
-                        */
-                       update_share_count(sc, ref->count,
-                                          ref->count + newref->count, newref);
-                       ref->count += newref->count;
-                       free_pref(newref);
-                       return;
-               }
+               if (!eie)
+                       ref->inode_list = newref->inode_list;
+               else
+                       eie->next = newref->inode_list;
+               trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
+                                                       preftree->count);
+               /*
+                * A delayed ref can have newref->count < 0.
+                * The ref->count is updated to follow any
+                * BTRFS_[ADD|DROP]_DELAYED_REF actions.
+                */
+               update_share_count(sc, ref->count,
+                                       ref->count + newref->count, newref);
+               ref->count += newref->count;
+               free_pref(newref);
+               return;
        }
 
        update_share_count(sc, 0, newref->count, newref);
        preftree->count++;
        trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
-       rb_link_node(&newref->rbnode, parent, p);
-       rb_insert_color_cached(&newref->rbnode, root, leftmost);
 }
 
 /*