Re: [RFC PATCH v2 1/7] statx: add I/O alignment information

On Mon, Jun 13, 2022 at 10:25:12PM -0700, Eric Biggers wrote:

While working on the man-pages update, I'm having second thoughts about the
stx_offset_align_optimal field.  Does any filesystem other than XFS actually
want stx_offset_align_optimal, when st[x]_blksize already exists?  Many network
filesystems, as well as tmpfs when hugepages are enabled, already report large
(megabytes) sizes in st[x]_blksize.  And all documentation I looked at (man
pages for Linux, POSIX, FreeBSD, NetBSD, macOS) documents st_blksize as
something like "the preferred blocksize for efficient I/O".  It's never
documented as being limited to PAGE_SIZE, which makes sense because it's not.

Yes.  While st_blksize is utterly misnamed, it has always aways been
the optimal I/O size.

Perhaps for now we should just add STATX_DIOALIGN instead of STATX_IOALIGN,
leaving out the stx_offset_align_optimal field?  What do people think?

Yes, this sounds like a good plan.