Date: Tue, 21 May 2002 17:30:11 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: Terry Lambert <tlambert2@mindspring.com> Cc: Maxime Henrion <mux@freebsd.org>, arch@freebsd.org Subject: Re: a virtual fs to allow root mounting of any fs without special code Message-ID: <Pine.NEB.3.96L.1020521172613.79313X-100000@fledge.watson.org> In-Reply-To: <3CEAB940.25FC9F7B@mindspring.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 21 May 2002, Terry Lambert wrote: > Robert Watson wrote: > > Spiffy. Once the nmount conversion is done, I'd love to have this in the > > base system. As we discussed out of band, my only real concern was that > > it wasn't quite a "real mount" in the sense that you don't use a 'struct > > mount' when bootstrapping. And, as we discussed, that's probably fine for > > this limited scenario, from my perspective, although you don't want people > > doing "mount -t rootfs foo /mnt" or anything. I'd be interested in > > hearing from others if they think the lack of a "heavy weight mount" is a > > problem. > > You need to do exactly what you said you don't want people doing, in > order to achieve proper jails that are indistinguishable by way of the > root mounts. What I'm saying is that if it's a limited-purpose file system that doesn't follow the normal conventions for vnodes and their relationship to a struct mount, we need to prevent people from mis-using the file system, as it will violate existing code assumptions about the presence of a struct mount under certain circumstances. If we would like people to be able to mount it just about anywhere following boot (as with any other synthetic file system), we'll need a heavy-weight struct mount, which rootfs currently doesn't have. That said, I'm not sure what you're saying applies. There's nothing special about "rootfs" itself, it's pretty minimalist, what's special about it is that it gives you a place to stick devfs during the bootstrap (etc) so that you can get rid of special mountroot mounting procedures for other file systems. I.e., the magic in Maxime's patch is in the general-purpose root mounting case in the boot code, not in rootfs itself. Robert N M Watson FreeBSD Core Team, TrustedBSD Project robert@fledge.watson.org NAI Labs, Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.NEB.3.96L.1020521172613.79313X-100000>