Fix ->d_lock locking order in unlazy_walk()



Make sure that child is still a child of parent before nested locking
of child->d_lock in unlazy_walk(); otherwise we are risking a violation
of locking order and deadlocks.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 258e43fd

fs/namei.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -433,6 +433,8 @@ static int unlazy_walk(struct nameidata nd, struct dentry dentry)
		goto err_parent;
		BUG_ON(nd->inode != parent->d_inode);
		} else {
		if (dentry->d_parent != parent)
		goto err_parent;
		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
		if (!__d_rcu_to_refcount(dentry, nd->seq))
		goto err_child;