kern/61810: mounts done within a chroot show up wrong and can't be unmounted from outside.

[Jilles Tjoelker]

The following reply was made to PR kern/61810; it has been noted by GNATS.

From: Jilles Tjoelker <jilles at stack.nl>
To: bug-followup at FreeBSD.org, cliftonr at bass.tikitechnologies.com
Cc:  
Subject: Re: kern/61810: mounts done within a chroot show up wrong and
 can't be unmounted from outside.
Date: Tue, 20 Jul 2010 01:27:54 +0200

 Somewhere in 5.x, umount was changed to allow such unmounts. If the
 passed name matches one in the mount list exactly, the unmount is done
 by fsid and does not depend on existence of any particular pathname. An
 fsid may also be specified directly.
 
 The "matches exactly" part may become somewhat problematic if
 vn_fullpath(9) were to be used to return pathnames in statfs returns.
 Also, vn_fullpath(9) is unreliable and the buffers in the statfs
 structure are pretty small, so the name as passed to nmount(2) would
 still be visible in various cases.
 
 -- 
 Jilles Tjoelker