configfs: mutex_lock_nested() fix

configfs_unregister_subsystem() nests a pair of inode i_mutex acquisitions,
and thus needs annotation via mutex_lock_nested().

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 8a3b6a1..452cfd1 100644 (file)
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1176,8 +1176,9 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
                return;
        }
 
-       mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
-       mutex_lock(&dentry->d_inode->i_mutex);
+       mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
+                         I_MUTEX_PARENT);
+       mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
        if (configfs_detach_prep(dentry)) {
                printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
        }