On Sat, Jan 18, 2020 at 11:07:58PM +1100, Aleksa Sarai wrote:

Patch changelog:
  v3:
   * Merge changes into the original patches to make Al's life easier.
     [Al Viro]
  v2:
   * Add include <linux/types.h> to openat2.h. [Florian Weimer]
   * Move OPEN_HOW_SIZE_* constants out of UAPI. [Florian Weimer]
   * Switch from __aligned_u64 to __u64 since it isn't necessary.
     [David Laight]
  v1: <https://lore.kernel.org/lkml/20191219105533.12508-1-cyphar@cyphar.com/ (local)>

While openat2(2) is still not yet in Linus's tree, we can take this
opportunity to iron out some small warts that weren't noticed earlier:

  * A fix was suggested by Florian Weimer, to separate the openat2
    definitions so glibc can use the header directly. I've put the
    maintainership under VFS but let me know if you'd prefer it belong
    ot the fcntl folks.

  * Having heterogenous field sizes in an extensible struct results in
    "padding hole" problems when adding new fields (in addition the
    correct error to use for non-zero padding isn't entirely clear ).
    The simplest solution is to just copy clone(3)'s model -- always use
    u64s. It will waste a little more space in the struct, but it
    removes a possible future headache.

This patch is intended to replace the corresponding patches in Al's
#work.openat2 tree (and *will not* apply on Linus' tree).

@Al: I will send some additional patches later, but they will require
     proper design review since they're ABI-related features (namely,
	 adding a way to check what features a syscall supports as I
	 outlined in my talk here[1]).

#work.openat2 updated, #for-next rebuilt and force-pushed.  There's
a massive update of #work.namei as well, also pushed out; not in
#for-next yet, will post the patch series for review later today.