cifs: timeout dfs automounts +little fix.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/cifs/cifs_dfs_ref.c

@@ -25,14 +25,26 @@
 
 static LIST_HEAD(cifs_dfs_automount_list);
 
-/*
- * DFS functions
-*/
+static void cifs_dfs_expire_automounts(struct work_struct *work);
+static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
+			    cifs_dfs_expire_automounts);
+static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
 
-void dfs_shrink_umount_helper(struct vfsmount *vfsmnt)
+static void cifs_dfs_expire_automounts(struct work_struct *work)
 {
-	mark_mounts_for_expiry(&cifs_dfs_automount_list);
-	mark_mounts_for_expiry(&cifs_dfs_automount_list);
+	struct list_head *list = &cifs_dfs_automount_list;
+
+	mark_mounts_for_expiry(list);
+	if (!list_empty(list))
+		schedule_delayed_work(&cifs_dfs_automount_task,
+				      cifs_dfs_mountpoint_expiry_timeout);
+}
+
+void cifs_dfs_release_automount_timer(void)
+{
+	BUG_ON(!list_empty(&cifs_dfs_automount_list));
+	cancel_delayed_work(&cifs_dfs_automount_task);
+	flush_scheduled_work();
 }
 
 /**
@@ -261,10 +273,11 @@ static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
 	err = do_add_mount(newmnt, nd, nd->path.mnt->mnt_flags, mntlist);
 	switch (err) {
 	case 0:
-		dput(nd->path.dentry);
-		mntput(nd->path.mnt);
+		path_put(&nd->path);
 		nd->path.mnt = newmnt;
 		nd->path.dentry = dget(newmnt->mnt_root);
+		schedule_delayed_work(&cifs_dfs_automount_task,
+				      cifs_dfs_mountpoint_expiry_timeout);
 		break;
 	case -EBUSY:
 		/* someone else made a mount here whilst we were busy */