overlayfs: fix lockdep misannotation

In an overlay directory that shadows an empty lower directory, say
/mnt/a/empty102, do:

 	touch /mnt/a/empty102/x
 	unlink /mnt/a/empty102/x
 	rmdir /mnt/a/empty102

It's actually harmless, but needs another level of nesting between
I_MUTEX_CHILD and I_MUTEX_NORMAL.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miklos Szeredi 2014-10-27 15:42:01 +01:00 committed by Al Viro
parent c2096537d4
commit d1b72cc6d8
3 changed files with 8 additions and 5 deletions

View file

@ -639,11 +639,13 @@ static inline int inode_unhashed(struct inode *inode)
* 2: child/target
* 3: xattr
* 4: second non-directory
* The last is for certain operations (such as rename) which lock two
* 5: second parent (when locking independent directories in rename)
*
* I_MUTEX_NONDIR2 is for certain operations (such as rename) which lock two
* non-directories at once.
*
* The locking order between these classes is
* parent -> child -> normal -> xattr -> second non-directory
* parent[2] -> child -> grandchild -> normal -> xattr -> second non-directory
*/
enum inode_i_mutex_lock_class
{
@ -651,7 +653,8 @@ enum inode_i_mutex_lock_class
I_MUTEX_PARENT,
I_MUTEX_CHILD,
I_MUTEX_XATTR,
I_MUTEX_NONDIR2
I_MUTEX_NONDIR2,
I_MUTEX_PARENT2,
};
void lock_two_nondirectories(struct inode *, struct inode*);