automount doesn't work with NFS root

[James E. Blair]

Binary package hint: autofs

Description: Ubuntu 8.04
Release: 8.04

autofs:
  Installed: 4.1.4+debian-2.1ubuntu1

I use autofs on a diskless machine which mounts / over NFS. In Ubuntu's autofs, the patch:

  debian/patches/077_dont_create_remote_dirs.dpatch

is applied, which causes automount to refuse to create the mount-point if it is not on a local filesystem (it decides this based on parsing /etc/mtab). Unfortunately, this change is not reflected in the documentation, which still reads:

       mount-point
              Base location for autofs-mounted filesystems to be attached. This is a
              directory name that will be created (as with mkdir -p) and later when
              automount terminates will be removed (as with rmdir -p).

So, it is a surprise that when I run autofs with an NFS root, if the mount-point does not exist when automount starts, it just logs:

  automount[8821]: failed to create iautofs directory /nfs

and exits. So, at the very least, the documentation should be updated, and it should give an appropriate error message indicating why it refuses to create the mount-point.

But this problem is exacerbated by the fact that the patch as written will still happily cause a remote mount-point to be removed on exit, regardless of whether it created it or not. So if the mount-point is on NFS, and exists, then automount will start, and upon exit, remove the mount-point, and will therefore fail to start a second time.

In trying to devise a solution to this problem, I was stumped by the lack of documentation, comments, or even a general description associated with the 077_dont_create_remote_dirs.patch. There are several ways to fix the problem that I'm having, but without knowing why the patch was included in the first place, I don't know what problem it was originally supposed to fix, and can't tell whether my solutions would cause a regression for whatever that problem was. I can say that whatever it was, it doesn't seem to affect my situation -- without the patch, automount works quite well on an NFS root system.

Perhaps the best solution is to add a new option to automount that would govern the behavior of creating the mount-point.

[Matteo Croce (teknoraver)]

This change to /etc/init.d/autofs fixes it

[click170 (click170)]

I also have a diskless client running Ubuntu 9.04 which mounts home directories from autofs.

The workaround suggested by Matteo Croce works in the meantime until a permanent solution is found.