Description of problem:

A NFS mount declared as "bg" in /etc/fstab doesn't work as expected. It ends up blocking the bootup process.

Version-Release number of selected component (if applicable):

systemd-208-9.fc20.x86_64

How reproducible:

100%

Steps to Reproduce:
1. Add a NFS mount of an unreachable NFS server in /etc/fstab, using "defaults,bg" as the mount options
2. Reboot

Actual results:

The reboot stalls at the mount job, waiting for a timeout.

Expected results:

The mount process should be backgrounded and the boot process continue immediately.

Additional info:

nfs(5) describes the bg mount option:

                      If  the  bg  option  is  specified, a timeout or failure
                      causes the mount(8) command to fork a child  which  con‐
                      tinues to attempt to mount the export.  The parent imme‐
                      diately returns with a zero exit code.  This is known as
                      a "background" mount.

The fstab line that triggers the bug on my system is:

192.168.0.2:/fud                          /fud                    nfs     defaults,bg     0 0

tore@sloth:~$ systemctl status fud.mount
fud.mount - /fud
   Loaded: loaded (/etc/fstab)
   Active: failed (Result: timeout) since ti. 2013-12-24 12:35:17 CET; 21s ago
    Where: /fud
     What: 192.168.0.2:/fud
  Process: 1132 ExecMount=/bin/mount 192.168.0.2:/fud /fud -t nfs -o defaults,bg (code=killed, signal=TERM)

des. 24 12:16:06 sloth.fud.no systemd[1]: fud.mount mounting timed out. Stopping.
des. 24 12:16:06 sloth.fud.no systemd[1]: Mounted /fud.
des. 24 12:35:17 sloth.fud.no systemd[1]: Unit fud.mount entered failed state.

As you can see from the timestamps above, the start job stalled for 20 seconds. This stalled the entire bootup process, too.