On Thu, Mar 30, 2017 at 10:08:10AM -0700, Linus Torvalds wrote:

What kind of new flag did you even have in mind that would have such
broken semantics that it would completely change the other flags?
Becuase now I'm starting to think that the whole series has an even
deeper bug: stupid new features that were badly thought out and not
even described.

Failure atomic file updates, aka O_ATOMIC:

	https://lwn.net/Articles/573092/

Currently the way to probe for it is a new ioctl to check if atomicy
is offered.  This should work, but it's rather fragile..