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Subject[PATCH 2/5] autofs - update autofs.txt for strictexpire mount option
A "strictexpire" mount option has been added to the autofs file

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.

Signed-off-by: Ian Kent <>
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
+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
 \ /
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