Package: debian-installer Severity: important /etc/mtab can be either a regular file updated by mount/umount, or a symlink to /proc/mounts. Currently, it is a regular file, though the user can change this by hand.
With linux < 2.6.26, /proc/mounts lacks information present in /etc/mtab such as additional mount options. Thus a symlink breaks things like discquotas which rely on parsing the additional mount options. As a result, we are mostly all still using it as a plain file. With linux >= 2.6.26, /proc/mounts contains all of the information in /etc/mtab, plus more. The mount system call can now pass all of the mount options to the kernel, so no information is missing in /proc/mounts. This has obviously useful benefits such as read-only root, and the state in /etc/mtab never gets out of sync with reality (there are a number of open bugs against mount where this occurs). Additionally, with the addition of per-process namespaces with CLONE_NEWNS to clone(2), each process has its own set of mounts, and as such a system-wide /etc/mtab is useless: it's only valid in one of the potentially many namespaces and can quickly get into a horrible mess. At this point, /etc/mtab *must* be a symlink to avoid breakage. Note that /proc/mounts is now a symlink to /proc/self/mounts for this reason: each process has potentially different mounts. After discussion on #debian-devel, we came up with these points: - we could detect the kernel version on boot, and set up a file or a symlink as needed. However, this breaks read-only root. - we could change on upgrades rather than boot, but because it's dependent upon the kernel version, breakage could result if an older kernel is booted. - doing it at install time if a kernel >= 2.6.26 is installed is the most robust solution. I had a look at a number of sources (debootstrap, base-files, debian-installer), but I have yet to find the code that initially creates /etc/mtab (if any). Some of the init scripts will re-create it if not present (and these could do with updating too for Lenny+1), but ideally if d-i installs a kernel >= 2.6.26, it should just ensure that /etc/mtab is a symlink during the install. If we could get this change made for Lenny, that would be great. Thanks for your time, Roger -- System Information: Debian Release: lenny/sid APT prefers testing APT policy: (500, 'testing') Architecture: i386 (i686) Kernel: Linux 2.6.20.3-bytemark-uml-2 Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/bash -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
