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Commit d1b72cc6 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Tested-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent c2096537

fs/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -2497,7 +2497,7 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 
	}



	mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);

	mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);

	mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2);

	return NULL;

}

EXPORT_SYMBOL(lock_rename);

fs/overlayfs/readdir.c

+1 −1
Original line number Diff line number Diff line
@@ -571,7 +571,7 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) 
{

	struct ovl_cache_entry *p;



	mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_PARENT);

	mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD);

	list_for_each_entry(p, list, l_node) {

		struct dentry *dentry;

include/linux/fs.h

+6 −3
Original line number Diff line number Diff line
@@ -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*);