On Tue, Aug 11, 2020 at 5:20 PM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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 <miklos@xxxxxxxxxx> wrote: > > > > > > > > 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