On Tue, Nov 10, 2015 at 12:32 AM, Mike Gilbert <flop...@gentoo.org> wrote: > On Mon, Nov 9, 2015 at 2:36 PM, Jarry <mr.ja...@gmail.com> wrote: >> On 08-Nov-15 17:58, Mike Gilbert wrote: >>> On Fri, Nov 6, 2015 at 12:19 PM, Jarry <mr.ja...@gmail.com> wrote: >>>> >>>> I noted one strange thing today: It seems one of my servers lost "/"! >>>> >>>> vs5-dns ~ # df >>>> Filesystem 1K-blocks Used Available Use% Mounted on >>>> /var/log/named 10138552 2223148 7377344 24% /chroot/dns/var/log/named >>>> tmpfs 308196 420 307776 1% /run >>>> dev 10240 0 10240 0% /dev >>>> shm 1540968 0 1540968 0% /dev/shm >>>> cgroup_root 10240 0 10240 0% /sys/fs/cgroup >>>> none 1048576 0 1048576 0% /var/tmp/portage >>> >>> Is your /etc/mtab a regular file, or is it a symlink to >>> /proc/self/mounts? The latter is recommended. >> >> It is regular file. I never changed it... >> >> vs5-dns ~ # ls -l /etc/mtab >> -rw-r--r-- 1 root root 908 Nov 9 19:14 /etc/mtab >> >>> Anyway, please have a look at the contents of /etc/mtab, >>> /proc/self/mounts, and proc/self/mountinfo while named is running and >>> when it is stopped. If you pastebin them we can take a look for key >>> differences. >> >> With bind running: >> http://pastebin.com/wkTW6xAY >> >> without bind: >> http://pastebin.com/JG5FPNDW >> >> While I can see some differences there, I still do not understand >> why is "/" missing in "df" output. BTW I can not proove it, but this >> was not the case all the time. At least when I was tuning monitoring >> software, I'm pretty sure "/" was there... > > It may be a bug. > > Can you try replacing /etc/mtab with a symlink to /proc/self/mounts to > see if it makes any difference? That triggers different code paths in > several programs.
>From the OP's pastebin: vs5-dns ~ # more /etc/mtab /dev/sda2 / ext4 rw,noatime,data=ordered 0 0 /etc/bind /chroot/dns/etc/bind none rw,bind 0 0 /var/bind /chroot/dns/var/bind none rw,bind 0 0 /var/log/named /chroot/dns/var/log/named none rw,bind 0 0 vs5-dns ~ # more /proc/self/mounts /dev/sda2 / ext4 rw,noatime,data=ordered 0 0 /dev/sda2 /chroot/dns/etc/bind ext4 rw,noatime,data=ordered 0 0 /dev/sda2 /chroot/dns/var/bind ext4 rw,noatime,data=ordered 0 0 /dev/sda2 /chroot/dns/var/log/named ext4 rw,noatime,data=ordered 0 0 There was a blog post a few years ago by the util-linux maintainer in which he was pushing for users to symlink "/etc/mtab" to "/proc/self/mounts" and he was explaining that having "bind" as a property in mtab doesn't make sense because you could unmount the "bound-to" mount and the "bound" mount would still show "bind" as a property. Is "/" shown when you run "df -a"? If it's shown, then there's a bug in coreutils (as long as they accept a bug on a system where mtab isn't a symlink) because, AFAIR, "df" should show the mount with the shortest mount path if a filesystem's mounted more than once.
