Commit 94c0d4ec authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl 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;