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Fix ->d_lock locking order in unlazy_walk()

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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>
This commit is contained in:
Al Viro 2011-07-12 21:40:23 -04:00
parent 258e43fdb0
commit 94c0d4ecbe
1 changed files with 2 additions and 0 deletions
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2
fs/namei.c
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@ -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;