Package: autofs
Version: 5.0.7-3
Severity: normal
Dear Maintainer,
* What led up to the situation?
Likely the cause was me reducing the TIMEOUT in /etc/default/autofs, but I
haven't verified this.
* What exactly did you do (or not do) that was effective (or
ineffective)?
Not sure what to answer here - I am using autofs.
* What was the outcome of this action?
automount regualrly tries (and sometimes succeeds) to unmount local
filesystems that are completely unrelated to its own mountpoint.
* What outcome did you expect instead?
automount should leave filesystems alone that it didn't mount itself.
The reason I don't know exactly what caused it (I am suffering^Wusing
autofs for many years now) is that it took me more than a month to
find out that automount is responsible for the magically disappearing
filesystems.
My auto.master looks like this:
/fs /etc/auto.fs
and auto.fs looks like this (this is an excerpt, full version available on
request, but I don't think any relevant lines are missing):
# yama
yama_wd -symlink :/fs/yama/wd
yama -vers=3,intr,tcp,rsize=1048576,wsize=1048576 \
/ yama:/ \
/wd yama:/wd \
# doom
doom_archiv_001 -symlink :/fs/doom/archiv_001
doom_archiv_002 -symlink :/fs/doom/archiv_002
doom_db -symlink :/fs/doom/db
doom_localvol2 -symlink :/fs/doom/localvol2
doom_localvol3 -symlink :/fs/doom/localvol3
doom_localvol4 -symlink :/fs/doom/localvol4
doom_localvol5 -symlink :/fs/doom/localvol5
doom -vers=3,intr,tcp,rsize=1048576,wsize=1048576 \
/ doom:/ \
/archiv_001 doom:/archiv_001 \
/archiv_002 doom:/archiv_002 \
/db doom:/db \
/localvol2 doom:/localvol2 \
/localvol3 doom:/localvol3 \
/localvol4 doom:/localvol4 \
/localvol5 doom:/localvol5 \
# rain
rain_localvol -symlink :/fs/rain/localvol
rain_localvol2 -symlink :/fs/rain/localvol2
rain -vers=3,intr,tcp,rsize=1048576,wsize=1048576 \
/ rain:/ \
/localvol rain:/localvol \
/localvol2 rain:/localvol2 \
# cerebro
cerebro_bp -symlink :/fs/cerebro/bp
cerebro_localvol -symlink :/fs/cerebro/localvol
cerebro_temp -symlink :/fs/cerebro/temp
cerebro_wd -symlink :/fs/cerebro/wd
cerebro -symlink :/
wd -symlink :/wd/
db -symlink :/db/
bp -symlink :/bp/
All of these, obviously, should be managed in /fs, and this more or less
works.
However, for some time now, /wd was "magically" being unmounted from time
to time. This also happene dto other mounted filesystems, but it was hard
to see a pattern.
After long time I decided to strace -f automount, to see if that is
responsible. And lo and behold, it is:
[pid 5814] open("/proc/mounts", O_RDONLY <unfinished ...>
...
[pid 5814] read(12, "rootfs / rootfs rw 0 0\nsysfs /sy"..., 1024) = 1024
[pid 5814] read(12, " binfmt_misc rw,nosuid,nodev,noe"..., 1024) = 1024
[pid 5814] read(12, "to=5,offset 0 0\ndoom:/localvol5 "..., 1024) = 251
[pid 5814] read(12, "", 1024) = 0
...
[pid 5807] umount("/wd", 0) = 0
[pid 5817] execve("/bin/umount", ["/bin/umount", "/fs/bp"], [/* 20 vars
*/]) = 0
[pid 5817] umount("/bp", 0) = -1 EBUSY (Device or resource busy)
[pid 5817] umount("/bp", 0) = -1 EBUSY (Device or resource busy)
[pid 5819] execve("/bin/umount", ["/bin/umount", "/fs/cerebro_localvol"],
[/* 20 vars */]) = 0
[pid 5819] umount("/localvol", 0) = -1 EBUSY (Device or resource busy)
[pid 5826] umount("/fs/doom/localvol5", 0) = -1 EBUSY (Device or resource
busy)
So basically, it read /etc/fstab and then tried to umount basically every
local filesystem. Looking at the strace output more closely reveals that
it simply calls umount on the entries in /fs, which are symlinks.
I guess the fix would be to not umount symlinks, as umount follows
symlinks.
-- System Information:
Debian Release: 7.5
APT prefers stable
APT policy: (990, 'stable'), (500, 'unstable'), (500, 'testing'), (500,
'oldstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 3.16.1-031601-generic (SMP w/12 CPU cores)
Locale: LANG=C, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages autofs depends on:
ii libc6 2.19-1
ii libxml2 2.9.1+dfsg1-4
ii multiarch-support 2.13-38+deb7u3
ii ucf 3.0025+nmu3
Versions of packages autofs recommends:
ii kmod 9-3
ii module-init-tools 9-3
ii nfs-common 1:1.2.6-4
autofs suggests no packages.
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