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>

1 files changed, 3 insertions, 11 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index aded3ef3d3d4..903fe68e017b 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -965,7 +965,7 @@ again:
         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;