Re: [RFC PATCH] autofs: find_autofs_mount overmounted parent support

[Al Viro]

On Mon, Mar 08, 2021 at 12:12:22AM +0000, Al Viro wrote:

> 	Wait, so you have /proc overmounted, without anything autofs-related on
> /proc/sys/fs/binfmt_misc and still want to have the pathname resolved, just
> because it would've resolved with that overmount of /proc removed?
> 
> 	I hope I'm misreading you; in case I'm not, the ABI is extremely
> tasteless and until you manage to document the exact semantics you want
> for param->path, consider it NAKed.

	BTW, if that thing would be made to work, what's to stop somebody from
doing ...at() syscalls with the resulting fd as a starting point and pathnames
starting with ".."?  "/foo is overmounted, but we can get to anything under
/foo/bar/ in the underlying tree since there's an autofs mount somewhere in
/foo/bar/splat/puke/*"?

	IOW, the real question (aside of "WTF?") is what are you using the
resulting descriptor for and what do you need to be able to do with it.
Details, please.