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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
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2
fs/namei.c
View File

@ -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);

2
fs/overlayfs/readdir.c
View File

@ -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;

9
include/linux/fs.h
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*);