[libvirt-users] LXC, libvrt-1.1.2-r3 (Gentoo), "/dev/tty12", mount /dev with inverse of 'nodev'?

[Dennis Jenkins]

Hello again,

TL;DR:

   Today I noticed that my LXC container was out of space in "/dev".  It
took me a few minutes to figure out why.  There were only 23 files there.
The "/dev" fs quota was 64K, and all was taken up.

    The problem was that "syslog-ng" was writing "console" messages to
"/dev/tty12".  But "/dev/tty12" was not a device node, so the kernel
"(2)open"ed it as a file and dutifully wrote to it.

   I have corrected my syslog-ng config, but I was wondering....

   Is there any legitimate reason to EVER have a regular file in "/dev"?
If not, can libvirt or Linux be modified so that the filesystem can be
mounted in such a way to prevent a regular file from ever being created
there?  Kind of like an inverse of the "nodev" mount option seen in various
filesystems (ext3, nfs).  IMHO, I would rather have syslog-ng (or other
tool) fail to open a regular file in "/dev", than for it is succeed and
then fill up the small fs.

   Thoughts?


Boring stuff:


Sep 30 14:06:47 localhost syslog-ng[440]: Error suspend timeout has
elapsed, attempting to write again; fd='16'
Sep 30 14:06:47 localhost syslog-ng[440]: I/O error occurred while writing;
fd='16', error='No space left on device (28)'
Sep 30 14:06:47 localhost syslog-ng[440]: Suspending write operation
because of an I/O error; fd='16', time_reopen='60'

   This is what I see inside the container:

djenkins at dwj-hfax-dev ~/src/HylaFAX+ $ find /dev | wc -l
23

dwj-hfax-dev ~ # ls -l /dev/tty*
crw-rw-rw- 1 root root  5, 0 Sep 30 13:44 /dev/tty
lrwxrwxrwx 1 root root    10 Sep 30 13:03 /dev/tty1 -> /dev/pts/0
-rw------- 1 root root 65536 Sep 30 14:12 /dev/tty12

### AHHH!!! There is the problem.  "syslog-ng" is writing to "/dev/tty12",
but it is a file and not a real device.


djenkins at dwj-hfax-dev ~/src/HylaFAX+ $ du -sh /dev
64K     /dev

djenkins at dwj-hfax-dev ~/src/HylaFAX+ $ df -h /dev
Filesystem      Size  Used Avail Use% Mounted on
devfs            64K   64K     0 100% /dev
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