vfs: don't use PARENT/CHILD lock classes for non-directories

Reserve I_MUTEX_PARENT and I_MUTEX_CHILD for locking of actual
directories.

(Also I_MUTEX_QUOTA isn't really a meaningful name for this locking
class any more; fixed in a later patch.)
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/inode.c

@@ -951,16 +951,16 @@ void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
 {
 	WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
 	if (inode1 == inode2 || !inode2) {
-		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
+		mutex_lock(&inode1->i_mutex);
 		return;
 	}
 	WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
 	if (inode1 < inode2) {
-		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
-		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
+		mutex_lock(&inode1->i_mutex);
+		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_QUOTA);
 	} else {
-		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
-		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
+		mutex_lock(&inode2->i_mutex);
+		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_QUOTA);
 	}
 }
 EXPORT_SYMBOL(lock_two_nondirectories);