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

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