Re: file metadata via fs API (was: [GIT PULL] Filesystem Information)

On Tue, Aug 11, 2020 at 5:20 PM Linus Torvalds
[off-list ref] wrote:

[ I missed the beginning of this discussion, so maybe this was already
suggested ]

On Tue, Aug 11, 2020 at 6:54 AM Miklos Szeredi [off-list ref] wrote:

quoted

quoted

E.g.
  openat(AT_FDCWD, "foo/bar//mnt/info", O_RDONLY | O_ALT);

Proof of concept patch and test program below.

I don't think this works for the reasons Al says, but a slight
modification might.

IOW, if you do something more along the lines of

       fd = open(""foo/bar", O_PATH);
       metadatafd = openat(fd, "metadataname", O_ALT);

it might be workable.

That would have been my backup suggestion, in case the unified
namespace doesn't work out.

I wouldn't think the normal lookup rules really get in the way if we
explicitly enable alternative path lookup with a flag.  The rules just
need to be documented.

What's the disadvantage of doing it with a single lookup WITH an enabling flag?

It's definitely not going to break anything, so no backward
compatibility issues whatsoever.

Thanks,
Miklos