Date: Thu, 25 Apr 2013 03:22:36 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Jamie Gritton <jamie@FreeBSD.org> Cc: freebsd-jail@FreeBSD.org Subject: Re: automatic garbage collection of stuff mounted (etc.) by jailed root Message-ID: <20130425012236.GB23151@dft-labs.eu> In-Reply-To: <51758192.2050300@FreeBSD.org> References: <20130422091711.GA3115@dft-labs.eu> <517553B0.6010602@FreeBSD.org> <517575BF.8020305@quip.cz> <51758192.2050300@FreeBSD.org>
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On Mon, Apr 22, 2013 at 12:29:38PM -0600, Jamie Gritton wrote: > On 04/22/13 11:39, Miroslav Lachman wrote: > >>This already happens when jails are created using a jail.conf file. Any > >>mounts there are unmounted as part of the jail removal process. Just > >>recently I fixed it to properly do this unmounting in reverse order. > > > >Do you mean mounts defined in jail.conf or all mounts manually done by > >root user in jail? > > > > Ah, I see the difference. Yes, that's only for mounts in the jail.conf. > For mounts done by the jail itself, I guess we would go off the mount > record's credential. So is this something you expect to be happening > entirely in the kernel? > If we want to clean this up from userspace, we need to teach the kernel how to export vnet and mount table of a jail and then it would be nice to teach jls how to print it (or maybe create a separate tool - jstat?), and of course jail(8) how to use this information to clean things up. Bonus points if jail(8) -r is able to clean up the jail without looking at config file. I would prefer if the jail would be able to just die if no problems were encountered and that is easly done with a kernel-only implementation, but this still would benefit from features described above (the difference would be that if someone wants to kill the jail, jail(8) would only call jail_remove). If jail could not die because some clean up operations failed, jls (or jstat) would show what resources are remaining along with error message (say, fs could not be unmounted because it was busy). And then the user can fix the problem and do jail(8) -r to re-run kernel clean up or clean on his own (say, unmount filesystems), which effectively should kill the jail. Thoughts? -- Mateusz Guzik <mjguzik gmail.com>
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