BTRFS_READ_LOCK
root_lock = BTRFS_READ_LOCK;
p->locks[level] = BTRFS_READ_LOCK;
p->locks[level] = BTRFS_READ_LOCK;
p->locks[level] = BTRFS_READ_LOCK;
path->locks[level] = BTRFS_READ_LOCK;
path->locks[level - 1] = BTRFS_READ_LOCK;
path->locks[level] = BTRFS_READ_LOCK;
else if (rw == BTRFS_READ_LOCK)
src_path->locks[cur_level] = BTRFS_READ_LOCK;
dst_path->locks[cur_level] = BTRFS_READ_LOCK;
path->locks[level] = BTRFS_READ_LOCK;
path->locks[level-1] = BTRFS_READ_LOCK;
path->locks[level] = BTRFS_READ_LOCK;