[$] Making O_TMPFILE atomic (and statx() additions)

Right on the heels of his previous filesystemsession at the2022 Linux Storage,Filesystem, Memory-management and BPF Summit (LSFMM), Steve French leda session on temporary files and their interaction with networkfilesystems.The problem is that creating temporary files is not always atomic, so he wasproposing changing that, which would eliminate a possible race conditionand be more efficient for network filesystems.Since the temporary-file discussion did not fill the 30-minute slot, however, French tookthe opportunity to discuss some attributes he would like to see get added for thestatx()system call.