From 092a53452bb7a6ca436b2d3859e7b1f1ec45479f Mon Sep 17 00:00:00 2001
From: Ian Kent <raven@themaw.net>
Date: Mon, 27 Feb 2017 14:27:16 -0800
Subject: [PATCH] autofs: take more care to not update last_used on path walk

GUI environments seem to be becoming more agressive at scanning
filesystems, to the point where autofs cannot expire mounts at all.

This is one key reason the update of the autofs dentry info last_used
field is done in the expire system when the dentry is seen to be in use.

But somewhere along the way instances of the update has crept back into
the autofs path walk functions which, with the more aggressive file
access patterns, is preventing expiration.

Changing the update in the path walk functions allows autofs to at least
make progress in spite of frequent immediate re-mounts from file
accesses.

Link: http://lkml.kernel.org/r/148577167169.9801.1377050092212016834.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/autofs4/root.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 82e8f6edfb48..d79ced925861 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -281,8 +281,8 @@ static int autofs4_mount_wait(const struct path *path, bool rcu_walk)
 		pr_debug("waiting for mount name=%pd\n", path->dentry);
 		status = autofs4_wait(sbi, path, NFY_MOUNT);
 		pr_debug("mount wait done status=%d\n", status);
+		ino->last_used = jiffies;
 	}
-	ino->last_used = jiffies;
 	return status;
 }
 
@@ -321,16 +321,21 @@ static struct dentry *autofs4_mountpoint_changed(struct path *path)
 	 */
 	if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
 		struct dentry *parent = dentry->d_parent;
-		struct autofs_info *ino;
 		struct dentry *new;
 
 		new = d_lookup(parent, &dentry->d_name);
 		if (!new)
 			return NULL;
-		ino = autofs4_dentry_ino(new);
-		ino->last_used = jiffies;
-		dput(path->dentry);
-		path->dentry = new;
+		if (new == dentry)
+			dput(new);
+		else {
+			struct autofs_info *ino;
+
+			ino = autofs4_dentry_ino(new);
+			ino->last_used = jiffies;
+			dput(path->dentry);
+			path->dentry = new;
+		}
 	}
 	return path->dentry;
 }
-- 
GitLab