lockdep: per filesystem inode lock class

Give each filesystem its own inode lock class. The various filesystems have
different locking order wrt the inode locks; esp. the pseudo filesystems differ
from the rest.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

fs/inode.c

@@ -142,6 +142,15 @@ static struct inode *alloc_inode(struct super_block *sb)
 			return NULL;
 		}
 
+		spin_lock_init(&inode->i_lock);
+		lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
+
+		mutex_init(&inode->i_mutex);
+		lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
+
+		init_rwsem(&inode->i_alloc_sem);
+		lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
+
 		mapping->a_ops = &empty_aops;
  		mapping->host = inode;
 		mapping->flags = 0;
@@ -190,8 +199,6 @@ void inode_init_once(struct inode *inode)
 	INIT_HLIST_NODE(&inode->i_hash);
 	INIT_LIST_HEAD(&inode->i_dentry);
 	INIT_LIST_HEAD(&inode->i_devices);
-	mutex_init(&inode->i_mutex);
-	init_rwsem(&inode->i_alloc_sem);
 	INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
 	rwlock_init(&inode->i_data.tree_lock);
 	spin_lock_init(&inode->i_data.i_mmap_lock);
@@ -199,7 +206,6 @@ void inode_init_once(struct inode *inode)
 	spin_lock_init(&inode->i_data.private_lock);
 	INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
 	INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
-	spin_lock_init(&inode->i_lock);
 	i_size_ordered_init(inode);
 #ifdef CONFIG_INOTIFY
 	INIT_LIST_HEAD(&inode->inotify_watches);

include/linux/fs.h

@@ -1302,8 +1302,13 @@ struct file_system_type {
 	struct module *owner;
 	struct file_system_type * next;
 	struct list_head fs_supers;
+
 	struct lock_class_key s_lock_key;
 	struct lock_class_key s_umount_key;
+
+	struct lock_class_key i_lock_key;
+	struct lock_class_key i_mutex_key;
+	struct lock_class_key i_alloc_sem_key;
 };
 
 extern int get_sb_bdev(struct file_system_type *fs_type,