Btrfs: send, avoid unnecessary inode item lookup in the btree

Regardless of whether the caller is interested or not in knowing the inode's
generation (dir_gen != NULL), get_first_ref always does a btree lookup to get
the inode item. Avoid this useless lookup if dir_gen parameter is NULL (which
is in some cases).

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index c76400d..98e9e0c 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1693,10 +1693,12 @@ static int get_first_ref(struct btrfs_root *root, u64 ino,
                goto out;
        btrfs_release_path(path);
 
-       ret = get_inode_info(root, parent_dir, NULL, dir_gen, NULL, NULL,
-                       NULL, NULL);
-       if (ret < 0)
-               goto out;
+       if (dir_gen) {
+               ret = get_inode_info(root, parent_dir, NULL, dir_gen, NULL,
+                                    NULL, NULL, NULL);
+               if (ret < 0)
+                       goto out;
+       }
 
        *dir = parent_dir;
 
@@ -1712,13 +1714,12 @@ static int is_first_ref(struct btrfs_root *root,
        int ret;
        struct fs_path *tmp_name;
        u64 tmp_dir;
-       u64 tmp_dir_gen;
 
        tmp_name = fs_path_alloc();
        if (!tmp_name)
                return -ENOMEM;
 
-       ret = get_first_ref(root, ino, &tmp_dir, &tmp_dir_gen, tmp_name);
+       ret = get_first_ref(root, ino, &tmp_dir, NULL, tmp_name);
        if (ret < 0)
                goto out;