autofs4 - reinstate last used update on access

When direct (and offset) mounts were introduced the the last used
timeout could no longer be updated in ->d_revalidate(). This is
because covered direct mounts would be followed over without calling
the autofs file system. As a result the definition of the busyness
check for all entries was changed to be "actually busy" being an open
file or working directory within the automount. But now we have a call
back in the follow so the last used update on any access can be
re-instated. This requires DCACHE_MANAGE_TRANSIT to always be set.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/autofs4/expire.c

@@ -294,7 +294,6 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 		spin_unlock(&sbi->fs_lock);
 		return NULL;
 	}
-	managed_dentry_set_transit(root);
 	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
 		struct autofs_info *ino = autofs4_dentry_ino(root);
 		ino->flags |= AUTOFS_INF_EXPIRING;
@@ -302,7 +301,6 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 		spin_unlock(&sbi->fs_lock);
 		return root;
 	}
-	managed_dentry_clear_transit(root);
 	spin_unlock(&sbi->fs_lock);
 	dput(root);
 
@@ -341,8 +339,7 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 		ino = autofs4_dentry_ino(dentry);
 		/* No point expiring a pending mount */
 		if (ino->flags & AUTOFS_INF_PENDING)
-			goto cont;
-		managed_dentry_set_transit(dentry);
+			goto next;
 
 		/*
 		 * Case 1: (i) indirect mount or top level pseudo direct mount
@@ -402,8 +399,6 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 			}
 		}
 next:
-		managed_dentry_clear_transit(dentry);
-cont:
 		spin_unlock(&sbi->fs_lock);
 	}
 	return NULL;
@@ -484,8 +479,6 @@ int autofs4_expire_run(struct super_block *sb,
 	spin_lock(&sbi->fs_lock);
 	ino = autofs4_dentry_ino(dentry);
 	ino->flags &= ~AUTOFS_INF_EXPIRING;
-	if (!d_unhashed(dentry))
-		managed_dentry_clear_transit(dentry);
 	complete_all(&ino->expire_complete);
 	spin_unlock(&sbi->fs_lock);
 
@@ -513,9 +506,7 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
 		spin_lock(&sbi->fs_lock);
 		ino->flags &= ~AUTOFS_INF_EXPIRING;
 		spin_lock(&dentry->d_lock);
-		if (ret)
-			__managed_dentry_clear_transit(dentry);
-		else {
+		if (!ret) {
 			if ((IS_ROOT(dentry) ||
 			    (autofs_type_indirect(sbi->type) &&
 			     IS_ROOT(dentry->d_parent))) &&