Why does autofs log "couldn't get ioctl fd for direct mount" error message while autofs service is restarting or shutting down on an NIS server?

Solution Unverified - Updated -

Environment

  • Red Hat Enterprise Linux
  • Automount
  • NIS server

Issue

  • While starting the autofs service on an NIS server, below messages are triggered in the "/var/log/messages" log eventhough all the shares(direct and indirect) are accessible and working fine.:

 Jun  3 14:01:01 testserver automount[10409]: do_umount_autofs_direct: couldn't get ioctl fd for direct mount /mymount
 Jun  3 14:01:01 testserver automount[10409]: do_umount_autofs_direct: couldn't get ioctl fd for direct mount /mount1
 Jun  3 14:01:01 testserver automount[10409]: do_umount_autofs_direct: couldn't get ioctl fd for direct mount /data
 Jun  3 14:01:01 testserver automount[10409]: do_umount_autofs_direct: couldn't get ioctl fd for direct mount /share

Resolution

  • If running autofs on an NIS server, then use either NIS or local files for automount maps (not both).
  • Change the automount entry in /etc/nsswitch.conf to look like
automount: files

OR

automount: NIS

Note: If the machine running autofs is NOT an NIS server, then it's okay to read automount maps from both NIS and local files as long as the same maps aren't defined in both places.

Root Cause

autofs is reading the direct maps from both NIS and the local files, but there's only one autofs mountpoint for each of those mounts so after it's unmounted the first time the mount point does not exist anymore, but we still go and try to unmount it again.

Diagnostic Steps

  • Check the umount pattern while the service is shutting down
Jun  3 15:01:41 testserver automount[1520]: umount_multi: path /mymount incl 0
Jun  3 15:01:41 testserver automount[1520]: umounted direct mount /mymount

At this point we've successfully unmounted it.  But we're going to call umount_multi again, and this time we get an error:

Jun  3 15:01:41 testserver automount[1520]: umount_multi: path /mymount incl 0
Jun  3 15:01:41 testserver automount[1520]: do_umount_autofs_direct: couldn't get ioctl fd for direct mount /mymount
  • Check the pattern while the service is coming up. Here we load the maps from local files.
Jun  3 15:01:59 testserver automount[960]: lookup_nss_read_map: reading map files auto.direct
Jun  3 15:01:59 testserver automount[960]: parse_init: parse(sun): init gathered global options: (null)

and then we read it in again via NIS:

Jun  3 15:01:59 testserver automount[960]: lookup_nss_read_map: reading map nis auto.direct
Jun  3 15:01:59 testserver automount[960]: parse_init: parse(sun): init gathered global options: (null)

and then we see what appears to be the /mymount autofs mountpoint being mounted twice:

Jun  3 15:01:59 testserver automount[960]: mounted direct on /mymount with timeout 300, freq 75 seconds
Jun  3 15:01:59 testserver automount[960]: do_mount_autofs_direct: mounted trigger /mymount
Jun  3 15:01:59 testserver automount[960]: remount_active_mount: trying to re-connect to mount /mymount
Jun  3 15:01:59 testserver automount[960]: mounted direct on /mymount with timeout 300, freq 75 seconds
Jun  3 15:01:59 testserver automount[960]: remount_active_mount: re-connected to mount /mymount

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