From 9200026623efb8d0383fa637a8926021d3de3482 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Tue, 14 May 2019 15:44:17 -0700 Subject: [PATCH] autofs: update autofs.txt for strictexpire mount option A "strictexpire" mount option has been added to the autofs file system. It is meant to be used in cases where a GUI continually accesses or an application frquently scans an automount directory tree causing an accumulation of otherwise unused mounts. Link: http://lkml.kernel.org/r/155287083000.12593.2722713092537666885.stgit@pluto.themaw.net Signed-off-by: Ian Kent Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/autofs.txt | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/autofs.txt b/Documentation/filesystems/autofs.txt index 05da806b1e88..ac50b47f02bd 100644 --- a/Documentation/filesystems/autofs.txt +++ b/Documentation/filesystems/autofs.txt @@ -240,11 +240,18 @@ Normally the daemon only wants to remove entries which haven't been used for a while. For this purpose autofs maintains a "`last_used`" time stamp on each directory or symlink. For symlinks it genuinely does record the last time the symlink was "used" or followed to find -out where it points to. For directories the field is a slight -misnomer. It actually records the last time that autofs checked if -the directory or one of its descendants was busy and found that it -was. This is just as useful and doesn't require updating the field so -often. +out where it points to. For directories the field is used slightly +differently. The field is updated at mount time and during expire +checks if it is found to be in use (ie. open file descriptor or +process working directory) and during path walks. The update done +during path walks prevents frequent expire and immediate mount of +frequently accessed automounts. But in the case where a GUI continually +access or an application frequently scans an autofs directory tree +there can be an accumulation of mounts that aren't actually being +used. To cater for this case the "`strictexpire`" autofs mount option +can be used to avoid the "`last_used`" update on path walk thereby +preventing this apparent inability to expire mounts that aren't +really in use. The daemon is able to ask autofs if anything is due to be expired, using an `ioctl` as discussed later. For a *direct* mount, autofs -- 2.30.2