From: Ian Kent <ikent@redhat.com>
Date: Tue, 28 Oct 2008 16:08:22 +0900
Subject: [fs] autofs4: correct offset mount expire check
Message-id: 20081028070822.10523.92323.stgit@zeus.themaw.net
O-Subject: [RHEL 5.3 PATCH 2/2] autofs4 - correct offset mount expire check
Bugzilla: 468187
RH-Acked-by: Jeff Moyer <jmoyer@redhat.com>

From: Ian Kent <raven@themaw.net>

This patch is the second of two patches needed to addresses bug 468187.

When checking a directory tree in autofs_tree_busy() we can incorrectly
decide that the tree isn't busy. This happens for the case of an active
offset mount as autofs4_follow_mount() follows past the active offset
mount, which has an open file handle used for expires, causing the file
handle not to count toward the busyness check.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index e79dd09..e96e81b 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -56,12 +56,23 @@ static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
 	mntget(mnt);
 	dget(dentry);
 
-	if (!autofs4_follow_mount(&mnt, &dentry))
+	if (!follow_down(&mnt, &dentry))
 		goto done;
 
-	/* This is an autofs submount, we can't expire it */
-	if (is_autofs4_dentry(dentry))
-		goto done;
+	if (is_autofs4_dentry(dentry)) {
+		struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+
+		/* This is an autofs submount, we can't expire it */
+		if (sbi->type == AUTOFS_TYPE_INDIRECT)
+			goto done;
+
+		/*
+		 * Otherwise it's an offset mount and we need to check
+		 * if we can umount its mount, if there is one.
+		 */
+		if (!d_mountpoint(dentry))
+			goto done;
+	}
 
 	/* Update the expiry counter if fs is busy */
 	if (!may_umount_tree(mnt)) {