Most Unix file systems don't have the semantics of a "move". You unlink an inode from a filename, and link another inode (usually the inode for the tmp file). T

Most Unix file systems don't have the semantics of a "move". You unlink an inode from a filename, and link another inode (usually the inode for the tmp file). Then you unlink the original tmp filename. As far as btrfs is concerned, there is no relation between these inodes, and without copying the file (like you suggest), you can't improve this.