Red Hat Bugzilla – Bug 116873
Timeouts Not Inherited by Submounts of Automount Daemon
Last modified: 2007-11-30 17:07:00 EST
Description of problem:
It appears that submounts (automount --submount /path/subpath
map_type ...) do not inherit the timeout parameter of their parent
mounts (automount --timeout seconds /path map_type ...), so they
expire according to the default timeout of 5 minutes rather than the
user-specified number of seconds.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. In /etc/auto.master:
/misc /etc/auto.misc --timeout=60
2. In /etc/auto.misc:
sub -fstype=autofs /etc/auto.sub
3. In /etc/auto.sub:
4. Make sure that some_valid_server:/some_valid_exported_path is
properly exported via /etc/exports on the appropriate server, and
make sure that it can be manually mounted on the client
where /etc/auto.sub has been installed
5. Restart autofs and cause /misc/sub/some_valid_exported_path to get
mounted using the following command:
6. Wait at least 1 minute, but no more than 4 minutes, and check to
see if /misc/sub/some_valid_exported_path is still mounted using the
df | grep /misc/sub/some_valid_exported_path
After 1 minute, the user-specified timeout in /etc/auto.master, the
mounted path /misc/sub/some_valid_exported_path is still mounted.
After 5 minutes, the autofs default timeout value, it gets
unmounted. Looking at the process table reveals that the parent
automount daemon has the "--timeout 60" flag, but its child only has
a "--submount" flag with no explicit timeout. As a result, the
parent remains mounted until the child gets unmounted after the
default timeout period has elapsed.
All children of the parent automount daemon should inherit the "--
timeout 60" flag from their parents. If this means re-examining
the /etc/auto.master file, so be it, but there must be a more elegant
way to communicate this timeout from the parent daemon to its
children, and from its children to all of their grandchildren.
Step #6 of "Steps to Reproduce" was wrong. Correction:
Do not use df as this will access the remote filesystem and prevent
the automounter from unmounting. Instead, check /etc/mtab directly
to see if the path is still mounted as follows:
grep /misc/sub/some_valid_exported_path /etc/mtab
Also, it seems to me that it would be very simple for the automount
daemon to inclue the appropriate "--timeout" flag when it spawns each
of its children with the "--submount" flag. This would be a quick,
easy, and presumably safe fix.
I'll look into this.
Autofs4 takes care of this, and we'll be moving to this in the next
An errata has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.