Btrfs: only add roots if necessary in find_parent_nodes()

find_all_leafs() dosen't need add all roots actually, add roots only
if we need, this can avoid unnecessary ulist dance.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index aded3ef3d3d4abfa6d61fa078a51e64e4b80be65..903fe68e017bdfd84f55cacae3adc182a47e9401 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -965,7 +965,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
        while (!list_empty(&prefs)) {
                ref = list_first_entry(&prefs, struct __prelim_ref, list);
                WARN_ON(ref->count < 0);
-               if (ref->count && ref->root_id && ref->parent == 0) {
+               if (roots && ref->count && ref->root_id && ref->parent == 0) {
                        /* no parent == root of tree */
                        ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
                        if (ret < 0)
@@ -1061,22 +1061,14 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
                                u64 time_seq, struct ulist **leafs,
                                const u64 *extent_item_pos)
 {
-       struct ulist *tmp;
        int ret;
 
-       tmp = ulist_alloc(GFP_NOFS);
-       if (!tmp)
-               return -ENOMEM;
        *leafs = ulist_alloc(GFP_NOFS);
-       if (!*leafs) {
-               ulist_free(tmp);
+       if (!*leafs)
                return -ENOMEM;
-       }
 
        ret = find_parent_nodes(trans, fs_info, bytenr,
-                               time_seq, *leafs, tmp, extent_item_pos);
-       ulist_free(tmp);
-
+                               time_seq, *leafs, NULL, extent_item_pos);
        if (ret < 0 && ret != -ENOENT) {
                free_leaf_list(*leafs);
                return ret;