Autofs mounts not disconnecting after inactive

autofsmountnfsrhel

I have autofs installed on several linux servers that are connecting to central NFS server for the users /home directories. It works great when mounting the directories on login, but the mounts never seem to timeout. I've checked /etc/sysconfig/autofs and the default is indeed set to 300, so these should be timing out after 5 minutes.

Restarting autofs does umount all of the directories, so I know it's capable.

I've attempted using lsof randomly on the directories but no files appear open at any time.

I've also mounted a random directory that I know is not active, but these never umount themselves. Some of these boxes have 10+ users that have logged in once, and the mounts never drop.

I'm just trying to find out of there is a better method to finding out why. I don't see anything specific in any logs.

Any suggestions are appreciated. Thanks!

UPDATE

I turned on debugging for autofs but it doesn't seem to reveal anything out of the ordinary. These logs were generated 7 minutes after the /home/user1 was initially mounted and after 6 minutes of inactivity. According to the 5 minute default, this should have been unmounted. I never saw a log come through that indicated an attempt was even made to umount.

Jan 11 12:52:00 linux automount[26505]: st_expire: state 1 path /home
Jan 11 12:52:00 linux automount[26505]: expire_proc: exp_proc = 3055176592 path /home
Jan 11 12:52:00 linux automount[26505]: expire_proc_indirect: expire /home/user1
Jan 11 12:52:00 linux automount[26505]: expire_proc_indirect: expire /home/user2
Jan 11 12:52:00 linux automount[26505]: expire_proc_indirect: expire /home/user3
Jan 11 12:52:00 linux automount[26505]: 3 remaining in /home
Jan 11 12:52:00 linux automount[26505]: expire_cleanup: got thid 3055176592 path /home stat 7
Jan 11 12:52:00 linux automount[26505]: expire_cleanup: sigchld: exp 3055176592 finished, switching from 2 to 1
Jan 11 12:52:00 linux automount[26505]: st_ready: st_ready(): state = 2 path /home

Update 2
After talking to Red Hat support about this, the solution ended up being to just shorten the timeout value for home directories. I did that and looks well. Something apparently is traversing the mount point every 2 1/2 to 3 minutes and causing this to stay up.

The solution was to add the timeout value to the /etc/auto.master file for that mapping:

 /home     /etc/auto_home --timeout=120

Best Answer

Besides TIMEOUT variable autofs has a checking interval:

# cat /var/log/messages
Jan 11 21:45:35 client automount[24804]: mounted offset on /net/server/share with timeout 300, freq 75 seconds

It is equal to TIMEOUT/4. Every TIMEOUT/4 seconds autofs asks kernel when directory was accessed last time. So in your environment you have directory umnounted after 375 seconds of inactivity.

To get more detailed log you should add LOGGING="debug" to /etc/sysconfig/autofs

Related Solutions

CentOS Autofs – How to Mount Under Each User’s Home Directory

I've done a lot of work with autofs and mounting a variety of different types of resources using it. You can check out the man page for autofs which does answer some of your questions if you can keep straight that when they're referring to $USER in the documentation, they're referring to the user that's running the autofs daemon. These are the variables that you get by default:

Variable Substitution

The following special variables will be substituted in the key and location fields of an automounter map if prefixed with $ as customary from shell scripts (Curly braces can be used to separate the field name):
ARCH    Architecture (uname -m)
CPU    Processor Type
HOST    Hostname (uname -n)
OSNAME    Operating System (uname -s)
OSREL    Release of OS (uname -r)
OSVERS    Version of OS (uname -v)
autofs provides additional variables that are set based on the user requesting the mount:

USER    The user login name
UID    The user login ID
GROUP    The user group name
GID    The user group ID
HOME    The user home directory
HOST    Hostname (uname -n)
Additional entries can be defined with the -Dvariable=Value map-option to automount(8).

You'd probably be tempted to use the -DUSER=$USER but this will only set $USER inside the autofs map file to the user that started the autofs daemon. The daemon is usually owned by a user such as root or a chrooted user specifically setup for autofs.

NOTE #1: a autofs file is comprised of a key and a value. The variables are only allowed for use within the value portion of a entry.

NOTE #2: If the -D=... switch does not override a built-in variable then $USER or $UID would contain the value of the person's $USER & $UID that is accessing the mount.

Limiting access to the CIFS share

Regarding your question of how to limit access to a CIFS mount, I don't see a way to accomplish this with autofs.

The credentials used to mount a CIFS share are used throughout the duration that the share is mounted. In effect, autofs, running it's daemon automount as say root, is "equivalent" to the credentials of the CIFS user.

This isn't what I would consider typical behavior for autofs and is a by-product of using mount.cifs. Typical autofs behavior would respect the permissions on the other end of the mount, whereas with mount.cifs it does not.

Bottom-line

I think you're out of luck accomplishing your setup using autofs. I think you're going to have to use fuse if you truly want each user to be accessing CIFS shares using their own credentials.

Best Answer

Related Solutions

CentOS Autofs – How to Mount Under Each User’s Home Directory

Limiting access to the CIFS share

Bottom-line

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