>
> It's been proposed that an alternative solution is to populate a
> directory with a direct map with symlinks. Unfortunately, that looks a
> little ugly, and <ls -lF /> would cause them all to be mounted, which
> is not desirable, I presume.
>
This is a general problem with direct mounts anyway.
The technical issue is that the Linux VFS doesn't support "sandwich
mounts", i.e. mounting a filesystem on top of the root of another
filesystem (in the case of a direct mount, the sandwiched filesystem
would be autofs, of course.) (Incidentally, we *know* this is what
Solaris uses.)
Sandwich mounts would eliminate an important optimization in the VFS,
and we don't want that (after all, the Linux filesystem is probably
the fastest one on the market, and we *want* that!)
However, you bring up a perfectly valid point, and one which I hadn't
really considered: it may be possible to use the dentry system to
trapdoor a directory without making it a proper mount. This is
definitely v2.3 stuff and means autofs-specific hooks in the VFS, but
if it can be done cleanly enough Linus just might let me do it. Now
you've given me something to think about. I can't say offhand if this
is doable, but I can't say offhand that it *isn't*, either...
Thanks for adding some technical content to this particular issue,
which was starting to degenerate into a few people thinking that if
they just whined loudly enough they would get their way...
-hpa
