Serious error in autofs docs, which has design implications

Hi, Ian Kent and other autofs people.

autofs.rst says:
> mounting onto a directory is considered to be "beyond a `stat`"
in https://elixir.bootlin.com/linux/v6.17-rc2/source/Documentation/filesystems/autofs.rst#L109

This is not true. Mounting does not trigger automounts.

mount syscall (
https://elixir.bootlin.com/linux/v6.17-rc2/source/fs/namespace.c#L4321
) calls "do_mount" (
https://elixir.bootlin.com/linux/v6.17-rc2/source/fs/namespace.c#L4124
), which calls "user_path_at" without LOOKUP_AUTOMOUNT.
This means automounts are not followed.
I didn't test this, but I'm pretty sure about this by reading code.

But what is worse, autofs.rst then proceeds to use this as an argument in
favor of introducing DCACHE_MANAGE_TRANSIT!

I. e. it seems that introducing DCACHE_MANAGE_TRANSIT rests on
wrong premise.

Thus, it seems (from reading autofs.rst) that DCACHE_MANAGE_TRANSIT and all accociated logic
can be removed from kernel.

--
Askar Safin
https://types.pl/@safinaskar