Description of problem:
Dovecot does not work, if users have autofs mounted home directories, because autofs does not seem to work reliably. Dovecot reported following error:

Error: chdir(/home/auto/afsuser) failed: Too many levels of symbolic links

Then I tried simple test:
================================
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <syslog.h>

int main(int argc, char **argv)
{
  char buf[200];
  int r = chdir("/home/nas/afsuser"), en=errno;
  snprintf(buf, 200, "Return code is: %d, errno=%d : %m\n", r, errno);
  syslog(LOG_ERR,buf);
  fprintf(stderr,buf);
  return r ? en : 0;
}
================================

added it to dovecot.service:
ExecStartPre=/opt/chdircheck

and added autoreboot.service
================================
[Unit]
Description=auto reboot
After=local-fs.target network.target
After=autofs.service
After=dovecot.service
After=chdircheck.service

[Service]
Type=oneshot
ExecStart=/usr/bin/reboot

[Install]
WantedBy=multi-user.target
================================

I also added debug "-d -v" to OPTIONS in /etc/sysconfig/autofs

after tens of reboots I checked /var/log/messages and there were 50 log messages, all of them:
automount[542]: dev_ioctl_send_ready: token = 1
chdircheck: Return code is: -1, errno=40 : Too many levels of symbolic links
automount[542]: mounted /home/nas/afsuser

so it was not working, with very odd chdir error

I verified that automount is started before dovecot:
cat /var/log/boot.log:
         Starting Automounts filesystems on demand...
.........
[  OK  ] Started Automounts filesystems on demand.
         Starting Dovecot IMAP/POP3 email server...
[  OK  ] Started Dovecot IMAP/POP3 email server.


I tried if it's race condition, so I removed it from dovecot and added it to autofs.service:
ExecStartPost=/opt/chdircheck

but it was working fine:

chdircheck: Return code is: 0, errno=0 : Success

so there is no problem with when dovecot/autofs is started.

Another test, I put chdircheck in own service:
================================
[Unit]
Description=autofs chdir check
After=local-fs.target network.target
After=autofs.service

[Service]
Type=oneshot
ExecStart=/opt/chdircheck

[Install]
WantedBy=multi-user.target
================================

tens of reboots again... working all the time. So, what is the difference? Why it works in autofs.service and own service, but not in dovecot.service? There is extra settings in dovecot.service, so I put it in too:
NonBlocking=yes
PrivateTmp=true

and it stopped working. Seems these options have negative side-effect why chdir stops waiting for mount to complete.


Version-Release number of selected component (if applicable):
systemd-44-17.fc17.x86_64
kernel-3.5.2-1.fc17.x86_64
autofs-5.0.6-22.fc17.x86_64

How reproducible:
always

Steps to Reproduce:
1) add new user
mkdir /home/auto
adduser -d /home/auto/afsuser afsuser
passwd afsuser

2) make home automount
new /etc/auto.home with following line:
afsuser -fstype=ext3,loop,rw :/home/disk.img
added "/home/auto /etc/auto.home" to /etc/auto.master
chkconfig autofs on
dd if=/dev/zero of=/home/disk.img bs=1M count=100
mkfs.ext3 -F /home/disk.img
mount /home/disk.img /mnt -oloop
mv /home/auto/afsuser /mnt
umount /mnt

3) gcc -o /opt/chdircheck chdircheck.c
# the source code is above

4) create chdircheck.service
# service content is above

5) add 
NonBlocking=yes
PrivateTmp=true
to service file

6) reboot
7) check log
grep chdircheck /var/log/messages | tail -n 1
  
Actual results:
chdircheck: Return code is: -1, errno=40 : Too many levels of symbolic links

Expected results:
chdircheck: Return code is: 0, errno=0 : Success

Additional info:
Without
NonBlocking=yes
PrivateTmp=true
it works fine