btrfs: Don't opencode btrfs_find_name_in_backref in backref_in_log

Direct replacement, though note that the inside of the loop in
btrfs_find_name_in_backref is organized in a slightly different way but
is equvalent.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -945,54 +945,30 @@ static noinline int backref_in_log(struct btrfs_root *log,
 				   const char *name, int namelen)
 {
 	struct btrfs_path *path;
-	struct btrfs_inode_ref *ref;
-	unsigned long ptr;
-	unsigned long ptr_end;
-	unsigned long name_ptr;
-	int found_name_len;
-	int item_size;
 	int ret;
-	int match = 0;
 
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
 
 	ret = btrfs_search_slot(NULL, log, key, path, 0, 0);
-	if (ret != 0)
-		goto out;
-
-	ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
-
-	if (key->type == BTRFS_INODE_EXTREF_KEY) {
-		if (btrfs_find_name_in_ext_backref(path->nodes[0],
-						   path->slots[0],
-						   ref_objectid,
-						   name, namelen))
-			match = 1;
-
+	if (ret != 0) {
+		ret = 0;
 		goto out;
 	}
 
-	item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
-	ptr_end = ptr + item_size;
-	while (ptr < ptr_end) {
-		ref = (struct btrfs_inode_ref *)ptr;
-		found_name_len = btrfs_inode_ref_name_len(path->nodes[0], ref);
-		if (found_name_len == namelen) {
-			name_ptr = (unsigned long)(ref + 1);
-			ret = memcmp_extent_buffer(path->nodes[0], name,
-						   name_ptr, namelen);
-			if (ret == 0) {
-				match = 1;
-				goto out;
-			}
-		}
-		ptr = (unsigned long)(ref + 1) + found_name_len;
-	}
+	if (key->type == BTRFS_INODE_EXTREF_KEY)
+		ret = !!btrfs_find_name_in_ext_backref(path->nodes[0],
+						       path->slots[0],
+						       ref_objectid,
+						       name, namelen);
+	else
+		ret = !!btrfs_find_name_in_backref(path->nodes[0],
+						   path->slots[0],
+						   name, namelen);
 out:
 	btrfs_free_path(path);
-	return match;
+	return ret;
 }
 
 static inline int __add_inode_ref(struct btrfs_trans_handle *trans,