vfs: fix d_inode_lookup() dentry ref leak

d_inode_lookup() leaks a dentry reference on IS_DEADDIR().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -1095,8 +1095,10 @@ static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentr
 	struct dentry *old;
 
 	/* Don't create child dentry for a dead directory. */
-	if (unlikely(IS_DEADDIR(inode)))
+	if (unlikely(IS_DEADDIR(inode))) {
+		dput(dentry);
 		return ERR_PTR(-ENOENT);
+	}
 
 	old = inode->i_op->lookup(inode, dentry, nd);
 	if (unlikely(old)) {