mountall hangs when fstab contains aufs entries because device='none', paths specified in options

[Hadmut Danisch]

Hi,

for a webdav application I need apache with dav and a aufs mounted directory. Therefore I have an entry

none /var/www/dav/Public aufs br:/mnt/local/archiv/Public_dav:/mnt/local/archiv/Public 0 0

in my fstab, which works when using mount from the command line. But it keeps the system from booting, not even the Singe-Use-Mode shell is available anymore. System hangs within mountall. The last thing to be seen is that mountall reports that mounting this entry fails.

I guess that at this time the other partitions are not yet mounted and thus the directories needed for this to work do not yet exist.

So mountall is a) not able to mount regular and correct entries in fstab and b) completely locks the machine even from admin access if so.

Even worse, that ubuntu startup system does not allow to add local scripts to be run between mounting regular disks and starting an apache. Really broken.

regards

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: mountall 2.15
ProcVersionSignature: Ubuntu 2.6.32-24.39-server 2.6.32.15+drm33.5
Uname: Linux 2.6.32-24-server x86_64
Architecture: amd64
Date: Thu Jul 7 11:39:22 2011
InstallationMedia: Ubuntu-Server 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.2)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/tcsh
SourcePackage: mountall

[Steve Langasek (vorlon)]

> none /var/www/dav/Public aufs br:/mnt/local/archiv/Public_dav:/mnt/local/archiv/Public 0 0

Yes, the problem here is that the information about the preconditions for mounting this filesystem entry are encoded in the options field using a filesystem-specific syntax. mountall doesn't (and shouldn't) know anything about this, so doesn't have enough information to mount this at the correct time.

Does aufs support a value other than 'none' for the first field? even if it ignored it, if this pointed to a file path we could then use the same handling for aufs as for bind mounts. (Bind mounts are currently *also* broken - bug #524972 - but then we could at least kill two birds with one stone.)

As far as this breaking the boot and giving you no option to insert your own local script: you can mark the filesystem 'noauto' in /etc/fstab, and add an upstart job like this:

start on mounted MOUNTPOINT=/mnt/local/archiv
exec mount /var/www/dav/Public

(or whatever the correct value for MOUNTPOINT is on your system)

[Steve Langasek (vorlon)]

So according to the mountall source, a possible workaround for this is to make sure the aufs entry in /etc/fstab is listed immediately after the filesystem that it depends on. This is underdocumented and shouldn't be required, but this will work for any filesystem that's marked 'nodev' in /proc/filesystems - which aufs is.